JP2010220448A - Four-wheel drive industrial vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a four-wheel drive industrial vehicle that can run even if idle running occurs in the front and rear wheels. <P>SOLUTION: A wheel loader includes: differential devices each disposed in the middle of the front axle and of the rear axle and connecting with a connection axle each other; and motors each provided at the end of each axle to drive the wheels. A control device 44 that controls each motor 41 includes: a speed ratio calculation part 46 that calculates the rotation speed ratios of the right and left wheels of the front and back sides based on the rotation speeds detected by encoders 45; an idle running decision part 47 that decides whether either one of the right and left wheels of the front and back sides is running idle or not based on the rotational speed ratios obtained by the speed ratio calculation part and the rotary radius ratios of the inner and outer wheels obtained beforehand; and a torque instruction part 48 that outputs a torque command to drop the torque of the motor 41 of the idle running wheel when the idle running is decided by the idle running decision part. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a four-wheel drive industrial vehicle, for example, a four-wheel drive wheel loader.

  As industrial vehicles, there are wheel loaders mainly used for construction and civil engineering. Among them, large-sized ones have a four-wheel drive system in which wheels are driven by electric motors respectively, and front and rear parts of the vehicle body. Some have adopted a refraction method that bends.

  The schematic configuration of such a wheel loader drive portion will be described with reference to FIG. 7. Differential devices 51 and 52 are respectively provided in the middle of the front and rear portions of the bottom frame (so-called chassis) of the vehicle body. Further, a front axle 53 (also referred to as an axle shaft) and a rear axle 54 are provided, and a connecting shaft (corresponding to a propeller shaft) that connects the differential devices 51 and 52 in the front-rear direction is provided at the center of the bottom frame. ) 55 is arranged. In addition, as each differential apparatus 51 and 52, a well-known differential gear apparatus is used.

  Electric motors 58 for individually rotating the front left and right wheels 56 and the rear left and right wheels 57 are provided at the front ends of the front axle 53 and the rear axle 54, respectively. In addition, while the one end side of the drive shaft of each electric motor 58 is each connected with the axles 53 and 54 side, the other end side is connected with each wheel 56 and 57 (for example, refer patent document 1).

Japanese Patent No. 3295046

  According to the above conventional configuration, the front and rear left and right wheels 56L, 56R; 57L, 57R are connected to each other via differential devices 51, 52, and the front and rear differential devices 51, 52 are also connected to each other. For example, when one of the left and right wheels 56 (or 57) on the front side (or the rear side) is idle due to slip, the rear side where no idle rotation has occurred (or A rotational driving force is transmitted from the front axle 54 (or 53), but there is a problem that the vehicle cannot travel when idling occurs on the front wheels 56 and the rear wheels 57.

  Therefore, an object of the present invention is to provide a four-wheel drive industrial vehicle that can run even when idling occurs on front and rear wheels.

In order to solve the above problems, the four-wheel drive industrial vehicle of the present invention has a front axle and a rear axle arranged at the front and rear of the vehicle main body frame, and a differential device is arranged in the middle of each axle. The front and rear differential devices are connected to each other by a connecting shaft, and a four-wheel drive industrial vehicle is provided with an electric motor for driving a wheel at the tip of each axle.
While having a control device for controlling each of the motors,
This controller
A speed ratio calculation unit that inputs the rotation speed detected by the rotation speed detector that detects the rotation speed of each wheel and calculates the rotation speed ratio between the left and right wheels on the front side and the rear side;
Based on the rotational speed ratio obtained by the speed ratio calculation unit and the rotational radius ratio of the inner and outer wheels at the minimum rotational radius of the industrial vehicle obtained in advance, either the left or right wheels on the front side and the rear side idle. An idling judgment unit for judging whether or not
When the idling determination unit determines that idling, the torque instruction unit outputs a torque command for reducing the torque of the motor of the idling wheel.

  According to the above configuration, by comparing the rotation speed ratio of the left and right wheels on the front and rear sides with the rotation radius ratio of the inner and outer wheels at the minimum rotation radius of the industrial vehicle, it is possible to determine which of the front and rear wheels. Determines whether the wheel is idling, and outputs a torque command to reduce the torque of the motor of the idling wheel when it is determined that idling has occurred in the front and rear wheels, respectively. Since it did in this way, the torque of the wheel which is idling can be reduced, the grip force with respect to the ground can be increased, and therefore it can be made into a runnable state.

1 is a side view of a four-wheel drive industrial vehicle according to an embodiment of the present invention. It is a top view of the industrial vehicle. It is a top view which shows the drive part of the industrial vehicle. It is a principal part top view of the differential apparatus of the industrial vehicle. It is a block diagram which shows schematic structure of the control apparatus in the industrial vehicle. It is a schematic plan view for demonstrating control of the industrial vehicle. It is a top view which shows the drive part of the same four-wheel drive type industrial vehicle of a prior art example.

Hereinafter, the four-wheel drive type industrial vehicle according to the embodiment of the present invention will be described based on specific examples.
In this embodiment, a wheel loader used for construction and civil engineering will be described as a four-wheel drive industrial vehicle. The wheel loader is capable of excavating and transporting earth and sand, is large-sized and has a four-wheel drive type, and further, the vehicle body can be refracted back and forth.

  As shown in FIGS. 1 and 2, the vehicle main body 1 of this wheel loader includes a front main body 2 having front wheels 4 on the left and right sides, and a rear main body 3 having rear wheels 5 on the left and right. The two main body portions 2 and 3 are connected to each other by a vertical connecting pin 6 so that they can be refracted, that is, can be converted, and a pair of left and right refractors provided between the two main body portions 2 and 3. In other words, turning (steering) is performed by a turning hydraulic cylinder (hereinafter referred to as a turning cylinder) 7.

  One end of a boom 11 is supported on the front main body 2 via a horizontal pin 12 so as to be tiltable in a vertical plane, and a bucket 14 is also connected to a vertical surface at the front end via a horizontal pin 13. A tilting hydraulic cylinder (hereinafter referred to as a tilting cylinder) 15 that tilts the boom 11 is attached between the boom 11 and the front main body 2. Further, a link body 17 that is long in the front-rear direction is supported by a middle pin of the boom 11 via a horizontal pin 16 so as to be swingable. The intermediate portion of the link body 17 is supported by the horizontal pin 16.

  The front end portion of the link body 17 and the rear surface side of the bucket 14 are connected via a link member 18, and the bucket 14 is vertically moved between the rear end portion of the link body 17 and the front main body portion 2. An oscillating hydraulic cylinder (hereinafter referred to as an oscillating cylinder) 19 is provided.

  Accordingly, by operating the tilting cylinder 15 with the operating lever provided in the driver's seat 8, the boom 11 can be tilted to move the bucket 14 in the vertical direction, and the swinging cylinder 19 is operated. Thus, the bucket 14 can be swung in the vertical direction. That is, the bucket 14 can be swung between a dumping posture in which the opening portion faces downward and a cloud posture.

Next, the four-wheel drive system that is the gist of the present invention will be described.
As shown in FIG. 3, the front and rear portions of the bottom frame of the vehicle main body 1 (which is a so-called chassis in the vehicle main body frame) (that is, the front main body portion 2 and the rear main body portion 3), respectively. A front axle (also referred to as a front axle shaft) 21 and a rear axle (also referred to as a rear axle shaft) 22 provided with differential devices 23 and 24 in the middle are disposed, and at the center of the bottom frame. A connecting shaft (corresponding to a propeller shaft) 25 is provided that is arranged in the front-rear direction and connects the two axles 21 and 22, that is, connects the differential devices 23 and 24. Accordingly, the left and right front axle portions 21a and 21b are provided on the left and right sides of the front differential device 23, and the rear left and rear right axle portions 22a and 22b are provided on the left and right sides of the rear differential device 24. Will be placed. A universal joint 26 (shown only in FIG. 6) is provided in the middle of the connecting shaft 25.

Known differential devices are used as the differential devices 23 and 24. Here, the differential devices 23 and 24 will be briefly described with reference to FIG.
The differential devices 23 and 24 include a differential case 31, a pair of left and right pinion gears 33 rotatably supported by the differential case 31 via pinion shafts (also referred to as spiders) 32, and the pinion gears 33 simultaneously. A pair of side gears 35 that are meshed with each other and rotatably supported by a differential case 31 via a rotation shaft 34 in the left-right direction; a ring gear 36 that is fixed to the differential case 31 with the same axis as the side gears 35; The ring gear 36 includes a pinion gear 38 that is provided at an end portion of the rotation shaft 37 in the front-rear direction, which is an axial direction orthogonal to the rotation axis of the ring gear 36 and meshed with the ring gear 36. The left and right rotation shafts 34 are connected to the corresponding axle portions 21 a, 21 b, 22 a and 22 b, and the front and rear rotation shaft 37 is connected to the connection shaft 25.

  Motors (electric motors) 41 for individually driving and rotating the wheels 4 and 5 are provided at the tip portions of the respective axle portions 21a, 21b, 22a, and 22b. One end side of the drive shaft of each motor 41 is connected to each axle portion 21a, 21b, 22a, 22b side, and the other end side is connected to wheels 4 and 5, respectively. The casing 22 is fixed to a casing (not shown). Each wheel 4, 5 has a built-in speed reducer 42.

Next, the drive control structure of the wheel loader will be briefly described.
That is, as shown in FIG. 5, an inverter (indicated by a virtual line in FIG. 2) 43 for controlling the rotation speed corresponding to each motor 41 is provided on the bottom frame of the vehicle body 1, A control device 44 is provided to control each inverter 43 to control the rotational speed of the wheels 4 and 5 (which is the rotational speed per unit time), and can detect the rotational speed of each of the wheels 4 and 5. For example, an encoder 45 is provided as a rotation speed detector. The encoder 45 is provided in each motor 41 or each axle part 21a, 21b, 22a, 22b, for example, and detects the rotational speed of the motor 41 or axle part 21a, 21b, 22a, 22b. is there.

Further, as shown in FIGS. 5 and 6, a detection signal from the rotation speed detector 44, that is, a rotation speed is input to the control device 44, and the rotation speed V _{fL of} the left and right front wheels 4L, 4R, Based on V _fR and the rotation speeds V _rL and V _rR of the rear wheels 5L and 5R, a speed ratio calculation for _obtaining a rotation speed ratio r1 of the inner ring and the outer ring (rotation speed of the outer ring / rotation speed of the inner ring: for example, V _fR / V _fL ). And the inner / outer ring rotation speed ratio r1 obtained by the speed ratio calculation section 46 and the inner / outer ring rotation speed ratio r1 and the inner ring rotation radius at the predetermined minimum rotation radius of the wheel loader. An idling determination unit that determines whether or not the wheels 4 and 5 are idling by comparing the radius r2 (R _o / R _i ), which is the ratio of (R _i ) and the outer ring radius (R _o ). 47 and this idling judgment Enter the determination result obtained at 47, and the torque instruction section 48 to output a torque command is provided to each inverter 43.

  The idling determination unit 47 compares the rotation speed ratio r1 of the inner and outer rings with the rotation radius ratio r2 of the inner and outer rings at the minimum rotation radius of the wheel loader, and the rotation speed ratio r1 of the inner and outer rings exceeds the rotation radius ratio r2. If it is, it is determined that the wheels 4 and 5 with the higher rotational speed are idling. For example, FIG. 6 shows a case where the front right wheel 4R and the rear left wheel 5L are idling (indicated by broken arrows).

  Then, the wheels 4R and 5L causing idling are output to the torque instruction unit 48, and a command to reduce the torque is output from the torque instruction unit 48 to the inverter 43 of the motor 41 corresponding to the wheels 4R and 5L. Is done. The torque command is, for example, an instruction to reduce the current torque to about 8% of the motor rated torque, for example.

  Then, such control is performed every predetermined time (for example, 20 msec), and when the rotation speed ratio r1 of the inner and outer rings becomes smaller than the rotation radius ratio r2, that is, when idling disappears, the original Return to torque value. This determination is also made by the idling determination unit 47. Therefore, when the idling determination unit 47 determines that idling has ceased, a command to return the torque from the torque instruction unit 48, that is, a torque increase command is issued. Is output.

  That is, during excavation / carrying work such as earth and sand by the wheel loader, for example, when one of the left and right wheels 4, 5 on the front side and the rear side slips and idles, the idling judgment unit 47 Is determined to be idle. Therefore, a command to reduce (suppress) the torque is output from the torque instruction section 48 to the motors 41 of the front and rear wheels 4 and 5 that are idling (more precisely, to the inverter 43). Thus, when the torque of the idle wheels 4 and 5 is reduced, the grip force (gripping force) of the wheels 4 and 5 with respect to the ground is recovered, so that slipping is eliminated and the vehicle can run.

When the slip is eliminated, a command for returning to the original torque is output from the idling determination unit 47 and the torque instruction unit 48.
As described above, by comparing the rotational speed ratio of the inner and outer rings on the front side and the rear side with the rotational radius ratio of the inner and outer rings at the minimum turning radius of the industrial vehicle, that is, based on the magnitude thereof, the front side and the rear side Torque that determines whether any of both wheels is idling and reduces the motor torque of the idling wheel when it is determined that idling has occurred on the front and rear wheels, respectively. Since the command is output, it is possible to decrease the torque of the idling wheel and increase the grip force with respect to the ground, and thus return to the runnable state.

  In the above embodiment, the case where the present invention is applied to a wheel loader has been described. Of course, the present invention is not limited to this wheel loader, and may be applied to other four-wheel drive industrial vehicles. It is.

DESCRIPTION OF SYMBOLS 1 Vehicle main body 2 Front side main-body part 3 Rear side main-body part 4 Front side wheel 5 Rear side wheel 21 Front axle 22 Rear axle 23 Differential gear 24 Differential gear 25 Connection shaft 41 Motor 43 Inverter 44 Control device 45 Encoder 46 Speed ratio calculation Unit 47 idling determination unit 48 torque instruction unit

Claims (1)

A front axle and a rear axle are arranged at the front and rear of the vehicle body frame, a differential device is arranged in the middle of each axle, and the front and rear differential devices are connected to each other by a connecting shaft. A four-wheel drive industrial vehicle in which an electric motor for driving a wheel is provided at the tip of each axle,
While having a control device for controlling each of the motors,
This controller
A speed ratio calculation unit that inputs the rotation speed detected by the rotation speed detector that detects the rotation speed of each wheel and calculates the rotation speed ratio between the left and right wheels on the front side and the rear side;
Based on the rotational speed ratio obtained by the speed ratio calculation unit and the rotational radius ratio of the inner and outer wheels at the minimum rotational radius of the industrial vehicle obtained in advance, either the left or right wheels on the front side and the rear side idle. An idling judgment unit for judging whether or not
A four-wheel drive type characterized by comprising a torque instruction unit for outputting a torque command for reducing the torque of the motor of the idling wheel when it is judged that the idling judgment unit is idling. Industrial vehicle.

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