JP2008144942A - Traction control system for construction vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine control system for a construction vehicle capable of improving work efficiency by temporarily raising the traction of the vehicle by simple operation when necessary even during control of suppressing traction such as traction control. <P>SOLUTION: In a wheel loader 1, when a traction control cancel button 35 is operated, and a determination result of a mode determining part 39 is a traction control operation mode (or a snow mode), a control part 16 carries out transition from the traction control operation mode (or the snow mode) wherein traction is set low, to a traction control cancel mode (or a snow mode cancel mode) wherein traction is temporarily raised. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a traction force control device for a construction vehicle such as a wheel loader.

In recent years, some construction vehicles such as wheel loaders drive a vehicle by driving a hydraulic pump by an engine and driving a traveling hydraulic motor by pressure oil discharged from the hydraulic pump. In such a construction vehicle, the speed and traction force of the vehicle are controlled by controlling the engine speed, the capacity of the hydraulic pump, and the capacity of the traveling hydraulic motor.
In particular, a construction vehicle equipped with a controller having a traction control function for adjusting the traction force of the vehicle with respect to the vehicle speed is used in order to prevent tire slipping during a scooping operation or the like on a slippery road surface.

For example, Patent Document 1 discloses a construction vehicle having such a traction control function.
JP 2004-144254 A (published May 20, 2004)

However, the conventional construction vehicle has the following problems.
That is, in the construction vehicle disclosed in the above publication, the traction force of the vehicle is reduced by limiting the maximum tilt angle of the traveling hydraulic motor under the setting conditions such as the traction control operation mode. During such control, if it is desired to temporarily increase the traction force during the hoisting operation or the like, a switch or dial (corresponding to the change-over switches 25 and 26 in Patent Document 1) for setting the traction control operation mode is provided. It is necessary to operate each time, and work efficiency may be reduced.

  An object of the present invention is to provide a construction capable of improving the working efficiency by temporarily raising the traction force of a vehicle by a simple operation when necessary even during control for suppressing traction force such as traction control. The object is to provide a traction force control device for a vehicle.

  A traction force control device for a construction vehicle according to a first aspect of the present invention is mounted on a construction vehicle that travels by driving a traveling hydraulic motor by pressure oil discharged from a traveling hydraulic pump driven by an engine, A traction force control apparatus for a construction vehicle having a traction control operation mode for reducing slippage and preventing slipping in a construction vehicle, a traction control setting unit, a mode determination unit, a traction control release operation unit, a control unit, It is equipped with. The traction control setting unit accepts the setting of the traction control operation mode. The mode determination unit determines whether or not the control mode is a traction control operation mode. The traction control release operation unit releases the traction control operation mode. When the mode determination unit determines that the mode is the traction control operation mode and the traction control release operation unit is operated, the control unit shifts to a traction control release mode that temporarily increases the traction force of the construction vehicle. .

  Here, it is mounted on a so-called HST construction vehicle that travels by driving a hydraulic motor with pressure oil from a hydraulic pump driven by an engine to prevent tire slip on a soft road surface in a low speed range. In the traction force control device for a construction vehicle having a traction control function for reducing the traction force of the vehicle, when performing a work requiring a larger traction force during the traction control operation mode, the traction control release operation unit is operated, Transition from the traction control operation mode to the traction control release mode.

  In addition, the said low speed driving | running means the driving speed of about 10 km / h or less at the time of working with a construction vehicle, for example. The traction control release operation unit refers to, for example, an operation button disposed on an operation lever or console box of a work machine. Further, the traction control control by the traction force control device includes a control for adjusting the maximum tilt angle of the traveling hydraulic motor.

  This allows the traction control release operation part to be operated if a large traction force is needed temporarily while the work is being performed while reducing the traction force in the low speed range to prevent tire slipping. Thus, the traction control operation mode can be temporarily canceled to easily obtain the required traction force and perform work efficiently. As a result, since the traction force can be temporarily increased by a simple operation in the traction control release operation unit, the work efficiency of the construction vehicle can be improved while ensuring the operability for the operator.

A traction force control device for a construction vehicle according to a second invention is the traction force control device for a construction vehicle according to the first invention, wherein the control unit performs control to adjust the maximum tilt angle of the traveling hydraulic motor. To switch the setting of the traction control operation mode.
Here, the traction force of the construction vehicle is controlled by adjusting the maximum tilt angle of the traveling hydraulic motor when the traction control is activated or released.
As a result, during low-speed traveling, the traction force of the construction vehicle can be easily increased or suppressed by adjusting the maximum tilt angle of the traveling hydraulic motor for the construction vehicle.

  A traction force control device for a construction vehicle according to a third aspect of the invention is the traction force control device for a construction vehicle according to the first or second aspect of the invention, wherein the control unit prevents slipping on the snowy road surface of the construction vehicle. It further has a snow mode for moving the peak position of the characteristic curve of the graph showing the vehicle speed-traction force characteristic toward the vehicle speed 0 side. And the traction force control apparatus of a construction vehicle is further provided with the snow mode setting part which receives the setting of snow mode. The mode determination unit determines whether or not the control mode is a snow mode. Further, when the control mode is determined to be the snow mode by the snow mode determination unit and the traction control release operation unit is operated, the control unit performs control to temporarily shift to the snow mode release mode. .

Here, in addition to the traction control operation mode, the traction control canceling operation portion of the traction control canceling operation unit is also set during the setting of the snow mode in which the peak position of the characteristic curve in the graph showing the vehicle speed-traction force characteristics of the construction vehicle is moved to the vehicle speed 0 side. Control is performed so as to shift to a snow mode release mode in which the traction force of the construction vehicle is temporarily increased by an operation.
As a result, even if the traction control operation mode or snow mode that suppresses the traction force in the low speed range of the construction vehicle is being set, the traction force can be temporarily increased relatively easily by operating the traction control release operation unit. Can do. As a result, even during work on a low friction road surface such as a soft road surface or a snowy road surface, a temporary increase in traction force can be easily obtained by a simple operation.

A traction force control device for a construction vehicle according to a fourth invention is the traction force control device for a construction vehicle according to the third invention, wherein the control unit is configured to enter an upper limit value of the engine speed when shifting to the snow mode. Is adjusted to shift the peak position of the torque curve.
Here, as control for shifting the peak position of the characteristic curve during the snow mode, the upper limit value of the engine speed is adjusted.
As a result, the engine speed in the low speed range is suppressed during the snow mode setting, so that the slip of the tire of the construction vehicle on the low friction road surface such as a snowy road surface can be reduced.

  A traction force control device for a construction vehicle according to a fifth invention is the traction force control device for a construction vehicle according to the third invention, wherein the control unit is configured to enter an upper limit value of the engine speed when shifting to the snow mode. In addition to the control for shifting the peak position of the torque curve by adjusting, the control for reducing the traction force is performed by adjusting the maximum tilt angle of the traveling hydraulic pump.

Here, during the snow mode setting, the upper limit value of the engine speed is adjusted to shift the peak position of the characteristic curve, and the maximum tilt angle of the traveling hydraulic pump is adjusted to increase the traction force of the construction vehicle. Control to reduce is also performed.
As a result, during the snow mode setting, the engine speed and the traction force of the construction vehicle in the low speed range are suppressed, so that the slip of the tire of the construction vehicle on the low friction road surface such as a snowy road surface can be reduced. .

A traction force control device for a construction vehicle according to a sixth aspect is the traction force control device for a construction vehicle according to any one of the first to fifth aspects, wherein the traction control release operation portion is operated again by the control portion. When it is detected, the traction control release mode returns to the traction control operation mode.
Here, in the traction control release mode in which the traction force is temporarily increased, when it is detected that the operator operates the traction control release operation unit again, the traction control release mode is returned to the traction control operation mode.

  As a result, after operating the traction control release operation unit to temporarily increase the traction force to perform operations such as scooping during low-speed traveling, the traction control release operation unit is By simply performing the operation again, it is possible to easily return to the traction control operation mode without consuming wasteful fuel.

A traction force control device for a construction vehicle according to a seventh aspect is the traction force control device for a construction vehicle according to any one of the first to sixth aspects, wherein the control unit includes a forward / reverse switching lever of the construction vehicle. When it is detected that the operation has been performed, the mode returns from the traction control release mode to the traction control operation mode.
Here, in the traction control release mode in which the traction force is temporarily increased, it is detected that the operator has performed an operation of moving the construction vehicle forward and backward, and the traction control release mode is returned to the traction control operation mode.
Normally, when the traction control is temporarily shifted to the traction control cancel mode during low speed traveling, the forward / reverse switching lever is often operated when the operation requiring the traction force is completed.

  For this reason, by recognizing the operation of the forward / reverse switching lever as a cue for the end of work requiring traction force, the original traction control is automatically canceled during normal operation without wasting fuel. You can return to mode. In combination with the above-described return by re-operation of the traction control release operation unit, for example, by causing the operator to select one of the return conditions, an appropriate release condition is set according to the operator's preference, work environment, or the like. be able to.

A traction force control device for a construction vehicle according to an eighth invention is the traction force control device for a construction vehicle according to any one of the first to seventh inventions, wherein the control unit has a vehicle speed of the construction vehicle equal to or greater than a predetermined value. When it is detected that the traction control has become, the traction control release mode is restored to the traction control release mode.
Here, in the traction control release mode in which the traction force is temporarily increased, it is detected by a speedometer or the like that the construction vehicle has traveled at a predetermined speed or more, and the traction control release mode is returned to the traction control operation mode.

Normally, in a situation where a construction vehicle is traveling at a high speed, the work in the traction control release mode that temporarily requires traction force is often completed.
As a result, by detecting the traveling speed of the construction vehicle and detecting that the vehicle has reached a predetermined value or more, it is possible to automatically return to the traction control operation mode without consuming wasteful fuel. It should be noted that the return by re-operation of the above-described traction control release operation unit and the return by operation of the forward / reverse switching lever are combined, for example, by allowing the operator to select one of the return conditions, the operator's preference, work environment, etc. Appropriate release conditions can be set according to the conditions.

  A traction force control device for a construction vehicle according to a ninth aspect is the traction force control device for a construction vehicle according to any one of the first to eighth aspects, wherein the control unit is configured as a traction control operation mode as a construction vehicle. There are a plurality of modes for switching the traction force in stages. And if a control part operates a traction control cancellation | release operation part, it will cancel | release one of several modes, and will transfer to traction control cancellation | release mode.

Here, in the traction control operation mode, a plurality of modes are provided in stages for each traction force, and when the traction control release operation unit is operated, the traction control is canceled regardless of which mode is set. Transition to mode.
As a result, the optimum traction force required at that time is preset by a plurality of modes included in the traction control operation mode, and when the maximum traction force is required, the traction control release mode is entered. And can be easily migrated. As a result, an appropriate traction force can be ensured according to the work situation, and the work can be performed efficiently.

A traction force control device for a construction vehicle according to a tenth invention is the traction force control device for a construction vehicle according to any one of the third to fifth inventions, wherein the traction control release operation portion is operated again by the control portion. When it is detected that the event has been made, the mode returns from the snow mode cancel mode to the snow mode.
Here, in the traction control release mode in which the traction force is temporarily increased, when it is detected that the operator operates the traction control release operation unit again, the mode returns from the snow mode release mode to the snow mode.

  As a result, after operating the traction control release operation unit to temporarily increase the traction force to perform operations such as scooping during low-speed traveling, the traction control release operation unit is By simply performing the operation again, it is possible to easily return to the snow mode without consuming fuel wastefully.

A traction force control device for a construction vehicle according to an eleventh aspect of the invention is the traction force control device for a construction vehicle according to any one of the third to fifth aspects, wherein the control unit includes a forward / reverse switching lever of the construction vehicle. When it is detected that the operation has been performed, the mode returns from the snow mode cancel mode to the snow mode.
Here, in the snow mode cancel mode in which the traction force is temporarily increased, it is detected that the operator has performed an operation of moving the construction vehicle forward and backward, and the snow mode cancel mode is returned to the snow mode.
Normally, when the traction force is temporarily required during low-speed traveling and the mode is shifted to the snow mode release mode, the forward / reverse switching lever is often operated when the operation requiring the traction force is completed.

  For this reason, by recognizing the operation of the forward / reverse switching lever as a cue for the end of work requiring traction force, the original snow mode is automatically canceled during normal operation without wasting fuel. You can return to mode. In combination with the above-described return by re-operation of the traction control release operation unit, for example, by causing the operator to select one of the return conditions, an appropriate release condition is set according to the operator's preference, work environment, or the like. be able to.

A traction force control device for a construction vehicle according to a twelfth aspect of the invention is the traction force control device for a construction vehicle according to any one of the third to fifth aspects, wherein the control unit has a vehicle speed of the construction vehicle equal to or greater than a predetermined value. When it is detected that it has become, it returns to the snow mode from the snow mode cancel mode.
Here, in the snow mode release mode in which the traction force is temporarily increased, it is detected by a speedometer or the like that the construction vehicle has traveled at a predetermined speed or more to return from the snow mode release mode to the snow mode.

Usually, in a situation where the construction vehicle is traveling at a high speed, the work in the snow mode release mode in which the traction force is temporarily required is often completed.
As a result, by detecting the traveling speed of the construction vehicle and detecting that it has become a predetermined value or more, it is possible to automatically return to the snow mode without consuming fuel wastefully. It should be noted that the return by re-operation of the above-described traction control release operation unit and the return by operation of the forward / reverse switching lever are combined, for example, by allowing the operator to select one of the return conditions, the operator's preference, work environment, etc. Appropriate release conditions can be set according to the conditions.

A traction force control apparatus for a construction vehicle according to a thirteenth aspect is the traction force control apparatus for a construction vehicle according to any one of the first to twelfth aspects, wherein the traction control release operation unit is attached to the construction vehicle. It is attached to the control lever that controls the work implement.
Here, a traction control release operation portion that is operated when shifting from the traction control operation mode to the traction control release mode is provided in an operation lever that operates a work machine mounted on the construction vehicle.

Usually, an operator who drives a construction vehicle operates while holding an operation lever for operating a work machine or the like during operation.
As a result, when the operator wants to temporarily increase the traction force during the traction control operation mode, it is easy to operate by simply operating the traction control release operation part attached to the operation lever that is being gripped during operation. In addition, the traction force of the construction vehicle can be increased. As a result, the operability at the time of shifting to the traction control cancellation mode can be improved.

  According to the traction force control device for a construction vehicle according to the present invention, when the traction force of the construction vehicle is being reduced, the traction force is temporarily increased by a simple operation of the traction control release operation unit. The work efficiency of the construction vehicle can be improved while ensuring the operability.

A wheel loader (construction vehicle) 1 equipped with a traction force control device for a construction vehicle according to an embodiment of the present invention will be described below with reference to FIGS.
The “traction control operation mode” that appears in the following description is to control the traction force of the wheel loader 1 by adjusting the maximum tilt angle of the hydraulic motor (travel motors (travel hydraulic motors 12 and 13 described later)). The “snow mode” means a limitation on the maximum number of revolutions of the engine 8, or a traveling hydraulic pump capacity (maximum capacity of a main pump 9 to be described later), a pilot given to the pump capacity control cylinder 23. It means a mode in which the traction force of the wheel loader 1 is controlled by control for adjusting the pressure or the like.

[Whole loader 1 overall configuration]
As shown in FIG. 1, a wheel loader (construction vehicle) 1 according to an embodiment of the present invention is a construction vehicle that can be self-propelled by tires 4 a and 4 b and that performs a desired work using a work machine 3. The wheel loader 1 includes a body frame 2, a work machine 3, tires 4 a and 4 b, and a cab 5.

  The vehicle body frame 2 includes a front frame 2a disposed on the front side and a rear frame 2b disposed on the rear side. The front frame 2a and the rear frame 2b are arranged in the horizontal direction at the center of the vehicle body frame 2. It is connected in a swingable state. The vehicle body frame 2 is equipped with a hydraulic drive mechanism 7 for driving the tires 4 a and 4 b and the work machine 3. The configuration of the hydraulic drive mechanism 7 will be described in detail later.

A work machine 3 and a pair of front tires 4a are attached to the front frame 2a. The rear frame 2b is provided with a cab 5, a hydraulic oil tank 6, a pair of rear tires 4b, and the like.
The work implement 3 is a device that is driven by pressure oil from the work implement hydraulic pump 11 (see FIG. 2), and includes a lift arm 37 attached to the front portion of the front frame 2 a and a tip of the lift arm 37. It has the attached bucket 38 and the work machine cylinder 26 (refer FIG. 2) which drives these.

The pair of front tires 4a is provided on the side surface of the front frame 2a. The pair of rear tires 4b are provided on the side surfaces of the rear frame 2b.
The cab 5 is mounted on the upper part of the vehicle body frame 2 and includes a steering wheel, an operation unit such as an accelerator, a display unit for displaying various information such as speed, a seat, and the like. The specific internal configuration of the cab 5 will be described in detail later.

The hydraulic oil tank 6 is arrange | positioned at the back of the cab 5, and accumulate | stores the hydraulic oil pressurized by various hydraulic pumps.
[Hydraulic drive mechanism 7]
As shown in FIG. 2, the hydraulic drive mechanism 7 mainly includes an engine 8, a main pump (travel hydraulic pump) 9, a charge pump 10, a work machine hydraulic pump 11, and a first travel motor (travel hydraulic motor) 12. And a second traveling motor (traveling hydraulic motor) 13, a clutch 14, a drive shaft 15, and a controller (control unit) 16 (see FIG. 3), and a so-called HST (Hydro Static Transmission) system is employed. .

  The engine 8 is a diesel engine, and output torque generated by the engine 8 is transmitted to a main pump 9, a charge pump 10, a working machine hydraulic pump 11, a steering hydraulic pump (not shown), and the like. The engine 8 is provided with a fuel injection device 17 for controlling the output torque and the rotational speed of the engine 8, and the throttle opening is adjusted in accordance with the accelerator operation amount (hereinafter referred to as “accelerator opening”). And adjust the fuel injection amount. The accelerator is a means for instructing the target rotational speed of the engine 8, and an accelerator opening detector 18 (see FIG. 3) is provided. The accelerator opening detection unit 18 is configured by a potentiometer or the like, and detects the accelerator opening. The accelerator opening detector 18 sends an opening signal indicating the accelerator opening to the controller 16, and a control signal is output from the controller 16 to the fuel injection device 17. For this reason, the operator can control the rotation speed of the engine 8 by adjusting the operation amount of the accelerator. Further, the engine 8 is provided with an engine speed detection unit 19 (see FIG. 3) that includes a rotation sensor that detects the actual speed of the engine 8, and the rotation speed signal from the engine speed detection unit 19 is a controller. 16 is input.

  The main pump 9 is a variable displacement hydraulic pump driven by the engine 8, and the pressure oil discharged from the main pump 9 passes through the main circuits 20 and 21, and the first travel motor 12 and the second travel motor 13. Sent to. The hydraulic drive mechanism 7 is provided with a main circuit oil pressure detector 22 (see FIG. 3) that detects the pressure of the pressure oil passing through the main circuits 20 and 21 (hereinafter referred to as “main circuit oil pressure”). The main circuit oil pressure corresponds to the drive oil pressure of the pressure oil that drives the first travel motor 12 and the second travel motor 13. The main pump 9 is connected to a pump capacity control cylinder 23 for controlling the capacity of the main pump 9 and a forward / reverse switching valve 24.

The charge pump 10 is a pump that is driven by the engine 8 and supplies pressure oil to the main circuits 20 and 21. The charge pump 10 supplies pressure oil to the pilot circuit of the main pump 9.
The working machine hydraulic pump 11 is driven by the engine 8. The pressure oil discharged from the work machine hydraulic pump 11 is sent to the work machine cylinder 26 of the work machine 3 via the work machine hydraulic circuit 25 to drive the work machine cylinder 26.

  The first traveling motor 12 is a variable displacement hydraulic motor and is driven by the pressure oil discharged from the main pump 9 to generate a driving force for traveling. The first traveling motor 12 is provided with a first motor cylinder 29 that controls the tilt angle of the first traveling motor 12 and a first motor control valve 30 (see FIG. 3) that controls the first motor cylinder 29. ing. The first motor control valve 30 is an electromagnetic control valve that is controlled based on a control signal from the controller 16, and controls the first motor cylinder 29 so that the capacity of the first travel motor 12 is reduced to the travel circuit pressure. The capacity according to The capacity of the first travel motor 12 is set to a capacity corresponding to the travel circuit pressure, as will be described later, in the case of high-speed travel driven by only the first travel motor 12. During low-speed traveling driven by both the second traveling motors 13, the first traveling motor 12 is fixed at the maximum capacity.

  Similar to the first travel motor 12, the second travel motor 13 is a variable displacement hydraulic motor driven by the pressure oil discharged from the main pump 9, and generates a driving force for travel on the drive shaft 15. Let The second traveling motor 13 is provided in parallel with the first traveling motor 12 on the hydraulic circuit. The second travel motor 13 includes a second motor cylinder 31 that controls the tilt angle of the second travel motor 13 and a second motor control valve 32 (see FIG. 3) that controls the second motor cylinder 31. Is provided. The second motor control valve 32 is an electromagnetic control valve controlled based on a control signal from the controller 16, and the capacity of the second travel motor 13 can be arbitrarily changed by controlling the second motor cylinder 31. it can. Further, the maximum tilt angle and the minimum tilt angle can be adjusted by adjusting the control signal applied to the second motor control valve 32.

  The clutch 14 is a device that switches between transmission and non-transmission of the driving force from the second travel motor 13 to the drive shaft 15. The clutch 14 is provided with a clutch control valve 33 (see FIG. 3) that switches engagement / disengagement of the clutch 14. The clutch control valve 33 is an electromagnetic control valve that switches engagement / disengagement of the clutch 14 based on a control signal from the controller 16. During low speed traveling, the clutch 14 is engaged, and the driving forces of the first traveling motor 12 and the second traveling motor 13 are transmitted to the drive shaft 15. During high speed travel, the clutch 14 is disengaged and only the driving force of the first travel motor 12 is transmitted to the drive shaft 15.

Here, the traction force of the wheel loader 1 in the low speed range is controlled by adjusting the maximum tilt angle of the second traveling motor 13 and switching the maximum capacity by setting a traction control operation mode to be described later. In addition, this low speed range means the speed | rate of 10.0 km / h or less at the time of performing a normal scraping work etc., for example.
The drive shaft 15 rotates the tires 4a and 4b by transmitting the driving force of the first travel motor 12 and the second travel motor 13 to the tires 4a and 4b (see FIG. 1). Further, the drive shaft 15 is provided with a vehicle speed detection unit 34 (see FIG. 3) that includes a vehicle speed sensor that detects the vehicle speed from the rotation speed of the drive shaft 15, and a vehicle speed signal from the vehicle speed detection unit 34 is sent to the controller 16. Entered.

  As shown in FIG. 3, the controller 16 includes a fuel injection device 17, an accelerator opening detector 18, an engine speed detector 19, a main circuit oil pressure detector 22, a forward / reverse switching valve 24, a first motor control valve 30, Second motor control valve 32, clutch control valve 33, vehicle speed detection unit 34, traction control release button (traction control release operation unit) 35, traction control switch (traction control setting unit, snow mode setting unit) 36, mode determination unit 39 The control block (traction force control device) 40 is connected to the forward / reverse switching lever 55 and the like. And the controller 16 electronically controls each control valve and the fuel injection device 17 based on the output signal from each detection part, and the engine speed, the capacity | capacitance of each hydraulic pump 9-11, and each traveling motor 12 and 13 are controlled. It is possible to control the capacity or the like, or to control the transition from the traction control operation mode to the traction control release mode, return, etc. by operating the traction control release button 35 or the like. Various control contents such as transition between the traction control release mode and the traction control operation mode and return control in the controller 16 will be described in detail later.

[Arrangement inside cab 5]
As shown in FIG. 6, the cab 5 is located in front of the operator seat (driver's seat) 42, the steering 43, the right console box 44, the front console box 46, and the right console box 44 and close to the operator seat 42. A work machine lever 53 is provided at the position. In addition, a forward / reverse switching lever 55 is disposed on the front side of the operator seat 42 in the lower part and the left side of the steering 43. The entrance doors 45a and 45b are attached to the left and right sides when the operator is seated on the operator seat 42.

The operator seat 42 is a seat on which an operator who operates the wheel loader 1 is seated, and is arranged near the center of the cab 5. The operator seat 42 is movable in the front-rear direction along a slide rail (not shown).
The steering 43 is attached so as to protrude from a front console box 46 disposed in front of the operator seat 42, and changes the traveling direction of the wheel loader 1 by rotating left and right.

  As shown in FIGS. 7 and 8, the right console box 44 is a box in which an armrest 51, a switch panel 52, and the like are arranged on the upper surface, and is arranged in a space between the operator seat 42 and the right entrance door 45a. Has been. The right console box 44 is movable in the front-rear direction along a slide rail (not shown). As shown in FIG. 7, the armrest 51 is disposed immediately behind the work implement lever 53, and an operator who operates the wheel loader 1 holds the work implement lever 53 with his arm (wrist) on the armrest 51. Operate the work implement 3 and the like while holding it. As shown in FIG. 8, the switch panel 52 is disposed immediately behind the armrest 51 and includes a plurality of switches.

The switches included in the switch panel 52 include a key switch 61 for starting the engine, vehicle speed range changeover switches 62 and 63, a switch group 64 including a fan reverse rotation switch, a T / C switch 36, and the like.
The work implement lever 53 is a lever for operating the work implement attached to the front of the wheel loader 1, that is, the movement of the lift arm 37 and the bucket 38 by tilting these two levers back and forth. The work implement lever 53 has a grip gripped by the operator at the upper portion, and the traction control release for executing the traction control release is performed on the grip upper surface of one of the work implement levers 53 (in this example, the outside). A button 35 is provided.

  As shown in FIG. 7, the traction control release button 35 is disposed at the upper end portion of the work machine lever 53, and a traction control switch 36, which will be described later, is operated to shift to a traction control operation mode or a snow mode and pulling force. This switch is used when the operator wants to temporarily increase the traction force in a state where the occurrence of slip is prevented by suppressing the occurrence of slip. That is, for example, as shown in FIGS. 12 (a) and 12 (b), the traction control release button 35 is operated when loading work such as earth and sand in the traction control operation mode or the snow mode. Thus, the state in which the traction force in the low speed range is suppressed by the traction control operation mode or the like can be released, and the traction force of the wheel loader 1 can be temporarily increased. Note that the switching control of the traction force by operating the traction control release button 35 during the setting of the traction control operation mode or the like during low-speed traveling will be described in detail later.

  The traction control switch 36 is included in a switch panel 52 disposed on the upper surface of the right console box 44 as shown in FIG. 8, and as shown in FIG. 9, a changeover switch 36a and a display unit 36b are provided. Have. The changeover switch 36a switches between three modes (traction control release mode, traction control operation mode, and snow mode) corresponding to the notations 36ba to 36bc shown in FIGS. 10 (a) to 10 (c). Specifically, in the neutral state of the changeover switch 36a as shown in FIG. 11 (a), the traction control operation mode shown in FIG. 10 (b) is entered, and the changeover switch 36a as shown in FIG. In the pressed state, the traction control release mode shown in FIG. 10B is entered, and in the state where the changeover switch 36a as shown in FIG. 11C is pushed backward, the snow mode shown in FIG. Each mode is switched as follows.

The notations shown in FIGS. 10B and 10C are displayed as a pilot lamp 75 on the instrument panel 70 installed in the cab 5 when the changeover switch 36a is switched to a corresponding state.
Specifically, as shown in FIG. 14, the instrument panel 70 provided in the cab 5 includes a warning unit 74 including an indicator lamp 74a including a speedometer 71, a shift display unit 72, a water temperature / oil temperature meter 73, and the like. A pilot lamp 75, a liquid crystal monitor 76, and the like are disposed. Then, during the operation of the traction control operation mode and the snow mode described above, the pilot lamp 75 is lit to notify the operator of the current setting mode.

  Further, when the above-described changeover switch 36a is in the neutral state shown in FIG. 11A, the traction control operation mode is set, and the traction force levels L1 to L3 at that time are shown in the front console box shown in FIG. By operating the two monitor panel mode change-over switches 46a and 46a installed at 46, it is set in advance via the screen of the liquid crystal monitor 76 (see FIG. 14). Specifically, by operating the monitor panel mode changeover switch 46a and moving the cursor to perform the function changeover operation of the character display, the magnitude of the traction force when shifting to the traction control operation mode is set in advance to the level L1. ~ L3 can be set. Thereby, the traction force of the wheel loader 1 in the traction control operation mode can be adjusted to an appropriate magnitude according to the situation of the work site.

  The forward / reverse switching lever 55 is a lever for switching the forward / reverse switching by controlling the forward / reverse switching valve 24. The forward / reverse switching lever 55 is connected to the controller 16 described above. When the forward / reverse switching lever 55 is operated during the traction control operation mode, the controller 16 is controlled so as to return to the traction control operation mode. To do.

<Control of Second Traveling Motor 13 in Traction Control Operation Mode>
In the present embodiment, when the traction control operation mode is set, the controller 16 adjusts the maximum tilt angle of the second traveling motor 13 to adjust the maximum capacity of the motor, and is transmitted to the tires 4a and 4b. The driving force is reduced to suppress the traction force of the wheel loader 1, and the occurrence of slip of the tires 4a and 4b in the low speed range is suppressed.

  Specifically, in the traction control operation mode or the like, the controller 16 processes output signals from the engine speed detection unit 19 and the main circuit oil pressure detection unit 22 to change the tilt angle to the second travel motor 13. Outputs a command. The solid line shown in FIG. 5 showing the relationship between the tilt angle, the main circuit oil pressure, and the engine speed is a line that defines the tilt angle with respect to the main circuit oil pressure when the engine speed is at a certain value. The tilt angle is minimum (Min) until the main circuit oil pressure is below a certain value, and then the tilt angle gradually increases as the main circuit oil pressure rises (inclined part in the solid line). After the angle reaches the maximum (Max), the tilt angle maintains the maximum tilt angle Max even if the hydraulic pressure increases.

  The sloped portion of the solid line is set so as to increase and decrease depending on the engine speed. That is, if the engine speed is low, the tilt angle increases from a state where the main circuit hydraulic pressure is lower, and is controlled so as to reach the maximum tilt angle when the main circuit hydraulic pressure is lower (the lower side in FIG. 5). (Refer to the sloped part of the broken line). On the contrary, if the engine speed is high, the minimum tilt angle Min is maintained until the main circuit hydraulic pressure becomes higher, and control is performed so as to reach the maximum tilt angle Max in a state where the main circuit hydraulic pressure is higher (in FIG. 5). (Refer to the sloped part of the upper broken line).

  In the present embodiment, the traction control switch 36 can be operated to switch between two states of the traction control on state and off state. When the traction control switch 36 is in the off state (see FIG. 11C), the maximum tilt angle is at the position Max in FIG. 5, and in this state, the vehicle speed-traction force characteristic is the traction control off in the graph of FIG. It becomes. When the traction control switch 36 is turned on (see FIG. 11A), the maximum tilt angle is changed from Max in FIG. 5 to Max ′. Thus, by changing the maximum tilt angle to Max ′, which is smaller than Max, a vehicle speed-traction force characteristic in which the maximum traction force is reduced as in the levels L1 to L3 in the graph of FIG. 4 is obtained. The levels L1 to L3 shown in the graph are vehicle speed-traction force characteristics when the accelerator opening is fully open. Further, the switching of the levels L1 to L3 in the graph of FIG. 4 is performed by operating the two monitor panel mode switching switches 46a and 46a installed in the front console box 46 as described above. As a result, on a low-friction road surface such as a soft road surface or a snowy road surface, the driving force of the tires 4a and 4b is suppressed to prevent slip even if the accelerator opening is maximized in order to secure the work amount by the work implement 3. Is possible.

<Limit control of the maximum engine speed of the engine 8 in the snow mode>
In this embodiment, as shown in FIGS. 10 (a) to 10 (c) and FIGS. 11 (a) to 11 (c), by operating the traction control switch 36, the traction control operation mode other than that described above is used. In addition, the snow mode can be selected. When the snow mode is selected, in addition to the adjustment of the maximum capacity of the motor, a control for moving the peak position of the characteristic curve to the vehicle speed 0 side in the graph showing the vehicle speed-traction force characteristic is also performed. The traction force characteristics as shown are obtained.

  That is, when the snow mode is set, the controller 16 adjusts the maximum tilt angle of the second traveling motor 13 to adjust the maximum capacity of the motor, thereby reducing the driving force transmitted to the tires 4a and 4b. Thus, the traction force of the wheel loader 1 is suppressed, and the peak position of the traction force is moved to the vehicle speed 0 side by gradually reducing the upper limit of the throttle opening as the vehicle speed of the wheel loader 1 decreases.

It should be noted that switching between the snow mode on and off states can be performed by operating the traction control switch 36. When the traction control switch 36 is operated so as to be in the state of FIG. 11B, the snow mode is turned on.
As a result, when the wheel loader 1 performs work in a low speed range, in the graph of FIG. 4 showing the vehicle speed-traction force characteristics, it is possible to perform control to reduce the traction force so that the characteristic curve becomes “snow mode”. it can.

<Traction force switching control in the low speed range while setting the traction control operation mode>
In the wheel loader 1 of the present embodiment, when the traction control release button 35 is operated by the operator while the traction control switch 36 is set to the traction control operation mode or the snow mode, the traction force of the wheel loader 1 is switched. Take control.

Here, first, the case where the traction control switch 36 is in the position of the traction control operation mode (see FIG. 10B and FIG. 11A) will be described.
In the traction control operation mode, as described above, the maximum tilt angle of the traveling motors 12 and 13 is adjusted to prevent the tires 4a and 4b from slipping on a soft road surface or the like, and the dotted line portion of the graph shown in FIG. As in (traction control on (levels L1 to L3)), control is performed to reduce the traction force of the wheel loader 1 in the low speed range.

  At this time, when the traction control release button 35 is operated by the operator, the controller 16 changes the maximum traction force of the wheel loader 1 by switching the maximum value of the tilt angle of the second traveling motor 13. Specifically, in the graph shown in FIG. 4, when the traction control release button 35 is operated once, the traction force increases from any of the levels L1 to L3 to the traction control off level, that is, the traction control operation mode is released. The traction control is turned off and the traction force is maximized.

Accordingly, even when the traction control switch 36 is set to the traction control operation mode in which the traction force of the wheel loader 1 is reduced, the traction control release button 35 is operated to respond to the work object, the ease of slipping on the road surface, and the like. Thus, the work can be performed while temporarily obtaining a desired traction force of the operator.
Next, the case where the traction control switch 36 is in the snow mode position (see FIG. 10C and FIG. 11B) will be described.

In the present embodiment, as described above, the snow mode control can be selected, and in addition to the maximum tilt angle control of the second traveling motor 13, the slip reduction control is performed by limiting the MAX rotational speed of the engine 8. .
At this time, when the traction control cancel button 35 is operated, the controller 16 cancels the limitation on the MAX rotational speed of the engine 8 and changes the maximum traction force of the wheel loader 1. Specifically, in the graph shown in FIG. 4, when the traction control release button 35 is operated once, the traction force increases from the snow mode level to the traction control off level, that is, the traction control operation mode is released and the traction control off state is entered. The traction force can be maximized. Thus, even when the traction control switch 36 is set to the snow mode and the maximum rotational speed of the engine 8 is limited, the traction force is switched by operating the traction control release button 35, so that the operator temporarily The work can be performed while obtaining the desired traction force.

Here, the control when the traction control release button 35 is operated in the state where the traction control operation mode or the snow mode as described above is set will be described with reference to the flowchart shown in FIG.
That is, in step S1, the mode determination unit 39 determines whether or not the control mode is the traction control operation mode (or snow mode), and if it is detected in step S2 that the traction control release button 35 has been operated, the control is performed. Only when the mode is the traction control operation mode or the snow mode, the process proceeds to step S3.

  In step S3, the traction control operation mode or the snow mode is shifted to the traction control release mode, and the traction force of the wheel loader 1 is temporarily increased. Specifically, in the case of the traction control operation mode, as shown in FIG. 5, the value of the maximum tilt angle of the second traveling motor 13 is changed from Max ′ to Max, and the traction force of the wheel loader 1 is increased. Let On the other hand, in the snow mode, the limitation on the maximum number of revolutions of the engine 8 is released, and the traction force of the wheel loader 1 is increased.

Next, in steps S4 to S7, control is performed to return the traction force to the original state by returning the traction force from the mode in which the traction force is increased in the traction control operation mode.
That is, in steps S4 to S6, a condition for returning to the original traction force when the traction control is canceled and the traction force of the wheel loader 1 is temporarily increased is set.

Specifically, in step S4, whether or not the traction control release button 35 has been operated again, whether or not the forward / reverse switching lever 55 has been operated in step S5, and in step S6, the detection result in the vehicle speed detection unit 34 is detected. It is determined whether or not it is a predetermined value (for example, 10 km / h) or more.
If any one of them is applicable, the process proceeds to step S7 and returns to the traction control operation mode (or snow mode) for suppressing the traction force of the wheel loader 1. That is, it is possible to prevent the tires 4a and 4b from slipping by returning to the original state where the traction force of the wheel loader 1 is suppressed. Specifically, when the traction control release mode 35 is in the traction control operation mode before being operated again, the maximum value of the tilt angle of the second traveling motor 13 is switched again from Max to Max ′. Thus, the traction force of the wheel loader 1 is returned to the original low value. On the other hand, if it is in the snow mode before the traction control release button 35 is operated again, the limit of the MAX rotational speed of the engine 8 is set to the original value, and the traction force of the wheel loader 1 is reduced to the original low value. Return to value.

  In the wheel loader 1 of the present embodiment, as described above, when the control mode is set to the traction control operation mode or the snow mode for suppressing the traction force in the low speed region in order to prevent the tires 4a and 4b from slipping, When the traction control release button 35 provided at the front end portion of the machine lever 53 is operated, the controller 16 adjusts the maximum tilt angle of the traveling motors 12 and 13 or the MAX rotational speed of the engine 8 to temporarily Control to increase the traction force.

As a result, when a traction force is temporarily required during work on a soft road surface or the like, the operator can easily obtain a desired traction force by simply operating the traction control release button 35 at the tip of the work machine lever 53. Since the work can be performed by being pulled out, the work efficiency can be significantly increased as compared with the conventional case.
[Features of the wheel loader 1]
(1)
In the wheel loader 1 of the present embodiment, as shown in FIG. 3, when the determination result in the mode determination unit 39 is the traction control operation mode, when the traction control release button 35 is operated by the operator, the controller 16 The mode is shifted from the traction control operation mode set to a low traction control release mode that temporarily increases the traction force.

  As a result, the traction control release button 35 is pressed when a work requiring a traction force is temporarily performed in a state where the traction control is operating in order to reduce the slip of the tires 4a and 4b on a soft road surface or the like. The traction force of the wheel loader 1 can be easily increased by such a simple operation. As a result, the operator can easily pull out a desired traction force without complicated operations and improve workability.

(2)
In the wheel loader 1 of the present embodiment, when the traction control release button 35 is operated to temporarily increase the traction force of the wheel loader 1 during the traction control operation mode, the maximum tilt angle of the traveling motors 12 and 13 is adjusted. To control.
That is, ON / OFF switching of the traction control operation mode in the wheel loader 1 is performed using the maximum tilt angle of the traveling motors 12 and 13.

Thereby, the traction force of the wheel loader 1 that has been suppressed in the traction control operation mode can be temporarily increased.
(3)
In the wheel loader 1 of this embodiment, in addition to the traction control operation mode, a snow mode that is selected at the time of work in a situation where the road surface is particularly low friction such as a road surface on snow is set. In this snow mode, as shown in FIG. 4, control is performed so that the peak position of the characteristic curve indicating the vehicle speed-traction force characteristic moves toward the vehicle speed 0 side.

  As a result, even when the work is performed by selecting the optimum mode for the work environment based on the work environment such as the road surface condition, the traction control release button 35 is operated to easily increase the traction force temporarily. It can be performed. As a result, during normal work, the traction force is suppressed according to the road surface condition, and the traction force is temporarily increased only when necessary while reducing the occurrence of slipping. Workability can be improved.

(4)
In the wheel loader 1 of the present embodiment, when the traction control release button 35 is operated to temporarily increase the traction force in the low speed region of the wheel loader 1 during the snow mode, as shown in FIG. Control is performed so that the upper limit value of the rotational speed is switched from Max ′ to Max.

As a result, the MAX rotational speed of the engine 8 that has been suppressed in the traction control operation mode is increased, and the peak position in the characteristic curve of the graph showing the vehicle speed-traction force characteristics is returned to the original, so that the traction force in the low speed region of the wheel loader 1 is restored. Can be raised temporarily.
(5)
In the wheel loader 1 of this embodiment, as shown in step S4 of FIG. 13, after the traction control release button 35 is operated to shift from the traction control operation mode to the traction control release mode, the traction control release button 35 is operated again. If this happens, the controller 16 returns to the traction control operation mode in which the traction force is set low in order to prevent slipping in the low speed range.

  As a result, when work that requires a large traction force temporarily ends, the traction control release button 35 that was operated when shifting to the traction control release mode is operated again as it is, so that the original traction force can be easily obtained. Can return to low traction control mode of operation. As a result, switching between the traction control operation mode and the traction control release mode can be performed with good operability at the timing desired by the operator.

(6)
In the wheel loader 1 of the present embodiment, as shown in step S5 of FIG. 13, the forward / reverse switching lever 55 is operated after the traction control release button 35 is operated to shift from the traction control operation mode to the traction control release mode. In this case, the controller 16 returns to the traction control operation mode in which the traction force is set low in order to prevent slipping in the low speed range.

  As a result, when an operation that temporarily requires a large traction force is completed, for example, it is assumed that the traveling direction is switched from the forward direction to the backward direction, so that it is detected that the forward / reverse switching lever 55 has been operated. Thus, it is possible to return to the traction control operation mode in which the original traction force is low. As a result, the return control from the traction control release mode to the traction control operation mode can be easily performed automatically regardless of the operation of the operator.

(7)
In the wheel loader 1 of the present embodiment, as shown in step S6 of FIG. 13, after the traction control release button 35 is operated to shift from the traction control operation mode to the traction control release mode, the vehicle speed of the wheel loader 1 exceeds a predetermined value. When the vehicle speed detection unit 34 detects that the vehicle has become, the controller 16 returns to the traction control operation mode in which the traction force in the low speed range is set low.

  As a result, when work that requires a large traction force temporarily ends, for example, it is assumed that the vehicle will move to another place at a certain vehicle speed, so the vehicle speed has exceeded a predetermined value while sensing the vehicle speed. By detecting this, it is possible to easily return to the traction control operation mode in which the original traction force is low. As a result, the return control from the traction control release mode to the traction control operation mode can be automatically performed regardless of the operation of the operator.

(8)
In the wheel loader 1 of the present embodiment, as shown in FIG. 4, the traction force in the low speed range can be switched and set in three stages (levels L1 to L3). The controller 16 switches to the traction control release mode by operating the traction control release button 35 regardless of the level L of the traction force.

That is, the traction force can be set in a plurality of stages in the same traction control operation mode, and the traction force can be set so as to obtain an appropriate traction force according to the situation at the work site or the like.
Thereby, according to various conditions such as the magnitude of the traction force desired by the operator, the condition of the road surface, the size and weight of the work object, it is possible to perform the work by selecting an appropriate traction force in advance, It is possible to work efficiently while minimizing the decrease in fuel consumption when the traction force is increased.

(9)
In the wheel loader 1 of the present embodiment, the traction control release button 35 that is operated when the traction force is temporarily raised from the traction control operation mode (or snow mode), as shown in FIG. Provided.
Usually, the operator places the right arm on the armrest 51 on the right console box 44 and operates the wheel loader 1 while holding the work implement lever 53.

As a result, when operating the traction control release button 35 provided on the work implement lever 53 that is normally held by the operator, it is only necessary to extend the thumb, so the operation for switching to the traction control release mode is performed. The operability can be improved.
[Other Embodiments]
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of invention.

(A)
In the above embodiment, the traction control operation mode and the snow mode are clearly distinguished from each other. However, if the traction control is defined as the traction force control of the construction vehicle in the low speed region, the traction control control includes a snow mode in which the peak position of the torque curve indicating the vehicle speed-traction force characteristic is moved to the vehicle speed 0 side. You can also think about it.

(B)
In the above embodiment, an example in which two traveling motors 12 and 13 are mounted as the configuration of the hydraulic drive mechanism 7 has been described. However, the present invention is not limited to this.
For example, as shown in FIGS. 15 and 16, hydraulic drive mechanisms 107 and 207 in which only one motor 12 is mounted as a traveling motor may be used.

(C)
In the above embodiment, as shown in FIG. 4, the traction force switching control of the wheel loader 1 during the traction control operation mode has been described by taking an example in which the traction force switching control is performed in one of the three levels L1 to L3. However, the present invention is not limited to this.
For example, as the traction force switching control, traction force switching control may be performed by setting traction force values in two stages or less, or four or more stages.

(D)
In the above embodiment, as shown in steps S4 to S6 of FIG. 13, when the traction control release button 35 is operated again, when the forward / reverse switching lever 55 is operated, or when the vehicle speed detected by the vehicle speed detection unit 34 is detected. An example of returning from a traction control release state with a high traction force to a traction control operation mode or a snow mode with a low traction force when the value exceeds a predetermined value has been described. However, the present invention is not limited to this.

For example, the return control can be performed by adding a condition other than the above, such as a predetermined time elapses, as a return condition to the traction control mode or the snow mode.
In addition, the above three conditions (steps S4 to S6) are not combined to perform the return control to the traction control operation mode or the snow mode, but are set to only one or two return conditions according to the setting of the operator. It is also possible.

(E)
In the above embodiment, the traction control release button 35 has been described with an example in which the traction control release button 35 is disposed at the tip of the work machine lever 53. However, the present invention is not limited to this.
For example, the traction control release button can be arranged in the switch panel on the right console box in the same manner as other switches.

However, it is more preferable to dispose the traction control release button as in the above-described embodiment in that it is provided on the work implement lever that the operator usually attaches to, so that the operability at the time of operation by the operator is high.
(F)
In the above embodiment, in both the traction control operation mode and the snow mode, the operation of the traction control release button 35 makes a transition to the state in which the traction control operation mode and the snow mode are released to temporarily increase the traction force of the wheel loader 1. An example of performing control has been described. However, the present invention is not limited to this.

For example, when the snow mode is set, the control is performed only during the setting to the traction control operation mode without performing the control to increase the traction force by shifting to the traction control release mode as in the above embodiment. You may make it apply.
(G)
In the above embodiment, as shown in FIG. 14, an example is shown in which the pilot lamp 75 that lights in the traction control operating state and the pilot lamp 75 that lights in the snow mode are displayed on the instrument panel 70 provided in the cab 5. explained. However, the present invention is not limited to this.

For example, you may make it display these lamps in the position where it is easy to see from operators other than an instrument panel.
(H)
In the said embodiment, the controller 16 gave and demonstrated the example which has traction control operation mode, snow mode, and traction control cancellation | release mode as a kind of control mode. However, the present invention is not limited to this.

For example, you may have other modes, such as power mode and economy mode.
(I)
In the said embodiment, the traction force control apparatus of the construction vehicle of this invention was given and demonstrated as the example mounted in the wheel loader 1. FIG. However, the present invention is not limited to this.

For example, the present invention can be applied to other construction vehicles that can run by driving a hydraulic motor.
In addition, the wheel loader 1 of the above embodiment is not limited to a construction vehicle that travels by driving two hydraulic motors. For example, a construction vehicle that travels by one or three or more hydraulic motors. Also good.

  The traction force control device for a construction vehicle according to the present invention can increase the traction force temporarily by a simple operation in the control release operation unit, and can improve the work efficiency of the construction vehicle while ensuring the operability of the operator. Since it produces an effect, it can be widely applied not only to construction machines but also to other traveling vehicles.

The perspective view which shows the whole structure of the wheel loader carrying the tractive force control apparatus which concerns on one Embodiment of this invention. Schematic which shows the structure of the hydraulic drive mechanism mounted in the wheel loader of FIG. The control block diagram comprised in the wheel loader of FIG. The graph which shows the relationship between tractive force and vehicle speed at the time of performing switching control of tractive force in the wheel loader of FIG. The graph which shows the relationship between the inclination angle of a traveling motor, main circuit oil_pressure | hydraulic, and engine speed in the wheel loader of FIG. The top view which shows the structure inside the cab mounted in the wheel loader of FIG. The perspective view which shows the structure of the front side periphery of the right side console box installed in the cab of FIG. The perspective view which shows the structure of the back side periphery of the right side console box installed in the cab of FIG. The perspective view which shows the structure of the traction control switch arrange | positioned on the right side console box of FIG. (A)-(c) is explanatory drawing which shows the mark arrange | positioned in the traction control switch vicinity of FIG. (A)-(c) is a side view which shows the switching state of the traction control switch of FIG. (A) And (b) is a schematic diagram which shows an example in case tractive force is needed temporarily while the wheel loader of FIG. 1 is working at low speed. The flowchart which shows the flow of control at the time of switching from the traction control operation mode in the wheel loader of FIG. 1 to the traction control cancellation mode, and returning from the traction control cancellation mode to the traction control operation mode. The front view which shows the display state of the driving | operation panel in the engine rotation limitation control in the wheel loader of FIG.

Explanation of symbols

1 Wheel loader (construction vehicle)
2 Body frame 3 Work machines 4a and 4b Tire 5 Cab 6 Hydraulic oil tank 7 Hydraulic drive mechanism 8 Engine 9 Main pump (travel hydraulic pump)
DESCRIPTION OF SYMBOLS 10 Charge pump 11 Working machine hydraulic pump 12 1st traveling motor (traveling hydraulic motor)
13 Second travel motor (travel hydraulic motor)
14 Clutch 15 Drive shaft 16 Controller (control unit)
Reference Signs List 17 Fuel injector 18 Accelerator opening detector 19 Engine speed detector 20 Main circuit 22 Main circuit oil pressure detector 23 Pump capacity control cylinder (hydraulic cylinder)
24 forward / reverse switching valve 25 working machine hydraulic circuit 26 working machine cylinder 29 first motor cylinder 30 first motor control valve 31 second motor cylinder 32 second motor control valve 33 clutch control valve 34 vehicle speed detection unit 35 traction control release button (Traction control release operation section)
36 Traction control switch (traction control setting part, snow mode setting part)
36a changeover switch 36b display unit 37 lift arm 38 bucket 39 mode determination unit 40 control block (traction force control device)
42 Operator seat 43 Steering 44 Right console box 45a, 45b Entrance door 46 Front console box 46a Monitor panel mode switching switch 51 Armrest 52 Switch panel 53 Working machine lever 55 Forward / reverse switching lever 61 Key switch 62, 63 Vehicle speed range switching switch 64 Switch group 70 Instrument panel 71 Speedometer 72 Shift display section 73 Water temperature / oil temperature gauge 74 Warning section 74a Indicator lamp 75 Pilot lamp 76 LCD monitor L level S step

Claims (13)

It is mounted on a construction vehicle that travels by driving a traveling hydraulic motor with pressure oil discharged from a traveling hydraulic pump driven by an engine, and reduces the traction force of the construction vehicle in a low speed region to prevent slipping. A traction force control device for a construction vehicle having a traction control operation mode,
A traction control setting unit for receiving setting of the traction control operation mode;
A mode determination unit for determining whether or not the control mode is the traction control operation mode;
A traction control release operation unit for releasing the traction control operation mode;
When the mode determination unit determines that the traction control operation mode is selected and the traction control release operation unit is operated, the mode transition unit temporarily shifts to the traction control release mode that increases the traction force of the construction vehicle. A control unit,
A traction force control device for construction vehicles. The control unit switches the presence or absence of setting of the traction control operation mode by performing control to adjust the maximum tilt angle of the traveling hydraulic motor.
The traction force control device for a construction vehicle according to claim 1. The control unit further includes a snow mode for moving a peak position of a torque curve of a graph showing a vehicle speed-traction force characteristic to the vehicle speed 0 side in order to prevent slipping on the snowy road surface of the construction vehicle,
A snow mode setting unit for accepting the setting of the snow mode;
The mode determination unit determines whether or not the control mode is the snow mode,
When the control mode is determined to be the snow mode by the snow mode determination unit and the traction control release operation unit is operated, the control unit temporarily shifts to the snow mode release mode. Do control,
The traction force control device for a construction vehicle according to claim 1 or 2. When the control unit shifts to the snow mode, the control unit adjusts the upper limit value of the engine speed and shifts the peak position of the torque curve.
The traction force control device for a construction vehicle according to claim 3. The control unit adjusts the maximum tilt angle of the traveling hydraulic pump in addition to the control for shifting the peak position of the torque curve by adjusting the upper limit value of the engine speed when shifting to the snow mode. Control to reduce the traction force by
The traction force control device for a construction vehicle according to claim 3. When the control unit detects that the traction control release operation unit is operated again, the control unit returns from the traction control release mode to the traction control operation mode.
The traction force control device for a construction vehicle according to any one of claims 1 to 5. When the control unit detects that the forward / reverse switching lever of the construction vehicle is operated, the control unit returns from the traction control release mode to the traction control operation mode.
The traction force control device for a construction vehicle according to any one of claims 1 to 6. When the control unit detects that the vehicle speed of the construction vehicle has reached a predetermined value or more, the control unit returns from the traction control release mode to the traction control operation mode.
The traction force control device for a construction vehicle according to any one of claims 1 to 7. The control unit has a plurality of modes for switching the traction force of the construction vehicle in stages as the traction control operation mode,
When the control unit operates the traction control release operation unit, the control unit releases any of the plurality of modes, and shifts to the traction control release mode.
The traction force control device for a construction vehicle according to any one of claims 1 to 8. When the control unit detects that the traction control release operation unit is operated again, the control unit returns from the snow mode release mode to the snow mode.
The traction force control device for a construction vehicle according to any one of claims 3 to 5. When the control unit detects that the forward / reverse switching lever of the construction vehicle is operated, the control unit returns from the snow mode release mode to the snow mode.
The traction force control device for a construction vehicle according to any one of claims 3 to 5. When the control unit detects that the vehicle speed of the construction vehicle has reached a predetermined value or more, the control unit returns from the snow mode release mode to the snow mode.
The traction force control device for a construction vehicle according to any one of claims 3 to 5. The traction control release operation part is attached to an operation lever for operating a work machine attached to the construction vehicle.
The traction force control device for a construction vehicle according to any one of claims 1 to 12.

Images