JP2007113304A - Hydraulic driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hydraulic driving device capable of providing workability suitable for respective operation sites in accordance with a user's need and improving fuel economy. <P>SOLUTION: This hydraulic driving device is provided with an engine 17, a hydraulic pump 18, a hydraulic actuator 20, a monitor panel 39 for allowing an operator to select desired work mode from among a plurality of work modes including power mode, usual economy mode, and first economy mode having different fuel economy in the engine 17, and an engine hydraulic pump controller 40. The engine hydraulic pump controller 40 controls the engine 17 and the hydraulic pump 18 in accordance with the work mode selected by the monitor panel 39, switches into operation in the power mode when predetermined work conditions are satisfied in the usual economy mode, and maintains operation in the first economy mode even if work conditions are satisfied in the first economy mode. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hydraulic drive device.

  As a conventional hydraulic drive device, those proposed in Patent Documents 1 and 2 are known. In the hydraulic drive device according to Patent Document 1, an engine output torque characteristic and a pump absorption torque characteristic that match a work mode selected by an operator are set. On the other hand, in the hydraulic drive device according to Patent Document 2, it is detected that the work implement is in a specific operation state by detecting a specific operation state of the operation lever, and the work implement is in a specific operation state. Further, the maximum value of the absorption torque of the hydraulic pump is set to a predetermined value in accordance with the operation state.

In the hydraulic drive device according to Patent Document 1, when the operator selects the heavy excavation mode, the engine is operated at full load, and the engine output torque characteristic indicated by the line ELa ′ in FIG. 15 is set. . In the engine output torque line ELa ′, the regulation line Ra ′ is set toward the set engine speed NA ′, and the engine output (horsepower) is set to be maximum at the engine speed Na ′. At this engine speed Na ′, the engine output torque is Ta ′ (hereinafter, the output torque point specified by the engine speed Na ′ and the engine output torque Ta ′ is referred to as “output torque point Ma ′”). ). Further, by adjusting the discharge oil amount of a variable displacement hydraulic pump (hereinafter simply referred to as “hydraulic pump”), a pump absorption torque characteristic indicated by a line PLa ′ in FIG. 15 is set. Here, the pump absorption torque line PLa ′ is a monotonically increasing function with the engine speed as a variable. Then, the output torque of the engine and the absorption torque of the hydraulic pump coincide with each other at the output torque point Ma ′ (hereinafter, this state is referred to as “matching”), and the engine horsepower at the output torque point Ma ′, that is, the engine The hydraulic pump absorbs maximum horsepower so that heavy excavation work can be performed with high efficiency. Thus, for example, the engine rotational speed Na ′ at the output torque point Ma ′ is set as a target value, and the absorption torque of the hydraulic pump is increased or decreased while calculating the deviation between the target rotational speed of the engine and the actual rotational speed, so that the output torque A control method for matching the output torque of the engine and the absorption torque of the hydraulic pump at the point Ma ′ is referred to as “engine speed sensing control” and is a known technique.
JP-A-2-38630 JP 2002-295408 A

  On the other hand, in the hydraulic drive device as described above, when a certain work mode is selected from a plurality of work modes, when a predetermined work condition is satisfied, the operation is automatically performed in another work mode. Some are designed to be switched. For example, a power mode that emphasizes workability and an economy mode that emphasizes fuel efficiency can be selected by an operator's operation, and a predetermined work condition is satisfied even when the economy mode is selected In some cases, the mode is automatically switched to the power mode. More specifically, in this hydraulic drive apparatus, when the power mode is selected, the output torque of the engine and the absorption torque of the hydraulic pump are matched at the output torque point Ma 'as shown in FIG. The output torque point Ma ′ is hereinafter referred to as “matching point Ma ′”) and is set by the same method as that of the hydraulic drive device according to Patent Document 1 described above. When the economy mode is selected, the engine output torque characteristic indicated by the line ELb ′ is set. Further, the pump absorption torque characteristic indicated by the line PLb 'is set by adjusting the discharge oil amount of the hydraulic pump. Then, the engine output torque and the absorption torque of the hydraulic pump are matched at the output torque point Mb specified by the engine speed Nb ′ and the engine output torque Tb ′ corresponding to the engine speed Nb ′ (hereinafter referred to as the engine torque Nb ′). The output torque point Mb ′ is referred to as “matching point Mb ′”). As described above, in the economy mode, the output torque of the engine and the absorption torque of the hydraulic pump are matched at the matching point Mb ′ where the fuel consumption rate (g / kw · h) is lower than the matching point Ma ′ in the power mode. Therefore, the engine can be used in an area where fuel efficiency is good, and fuel consumption can be improved.

  Further, in this hydraulic drive device, when a predetermined work condition is satisfied even when the economy mode is selected, the output torque of the engine and the absorption torque of the hydraulic pump are matched at the matching point Ma ′. For example, in the excavator, when the economy mode is selected and the upper turning body is turned and the boom is raised, the matching point Ma ′ in the power mode is The engine output torque and the hydraulic pump absorption torque are matched. Thereby, the hydraulic pump can effectively absorb the maximum horsepower of the engine, and the excavation operation of the earth and sand and the boom raising operation can be performed with high efficiency. When the turning / boom raising operation is changed to the turning / boom lowering operation, the output torque of the engine and the absorption torque of the hydraulic pump are matched at the matching point Mb ′. As a result, the output of the engine and the output of the hydraulic pump are suppressed, so that wasteful fuel consumption can be reduced as a total amount.

  As described above, in the hydraulic drive device as described above, fuel economy can be improved by selecting the economy mode, and workability can be improved by automatically switching to the power mode when necessary. Can be improved.

  However, in such a hydraulic drive device, when a predetermined work condition is satisfied, the mode is always switched to the power mode. However, since the situation of the operation site varies depending on the place or time, it is not necessary to switch to the power mode. In some cases. For example, in the field where it is not necessary to quarry less than usual and the amount of work is small, it is desirable to continue driving with low fuel consumption without switching to the power mode in order to improve fuel consumption. In such a situation, a decrease in workability is not a problem.

  An object of the present invention is to provide a hydraulic drive device that can provide workability suitable for each operation site and improve fuel efficiency in accordance with user needs.

  The hydraulic drive device according to the first invention includes an engine, a hydraulic pump, a hydraulic actuator, a selection device, and a control unit. The hydraulic pump is driven by the engine. The hydraulic actuator is operated by pressure oil discharged from a hydraulic pump. The selection device is a device for the operator to select a desired work mode from among a plurality of work modes including a first work mode, a second work mode, and a third work mode, each of which has different fuel consumption in the engine. The control unit controls the engine and the hydraulic pump according to the work mode selected by the selection device, and switches to the operation in the first work mode when a predetermined work condition is satisfied in the second work mode, In the third work mode, the operation in the third work mode is maintained even if the work conditions are satisfied.

  In the hydraulic drive device, when the second work mode is selected, the first work mode is automatically switched when a predetermined work condition is satisfied. Therefore, the work can be performed in a work mode suitable for the work conditions. If the user does not want to automatically switch from the second work mode to the first work mode, selecting the third work mode allows the user to operate in the third work mode regardless of the work conditions. You can continue. Thereby, in this hydraulic drive device, workability suitable for each operation site can be provided and fuel efficiency can be improved in accordance with user needs.

  The hydraulic drive device according to the second invention is the hydraulic drive device of the first invention, wherein the first work mode is a work mode in which the absorption horsepower at the hydraulic pump is larger than in the second work mode and the third work mode. . Further, the second work mode and the third work mode are work modes in which the fuel consumption in the engine is better than in the first work mode.

  In this hydraulic drive device, when workability is important, the workability can be improved by selecting the first work mode. When the fuel efficiency is more important than the workability, the fuel efficiency can be improved by selecting the second work mode or the third work mode. In particular, when there is little need to improve workability through a series of work, the transition to the first work mode can be prohibited by selecting the third work mode, and the fuel consumption can be further improved.

  A hydraulic drive device according to a third invention is the hydraulic drive device according to the second invention, wherein the third work mode is a work mode in which the absorption horsepower in the hydraulic pump is smaller than that in the second work mode and the fuel consumption in the engine is good. It is.

  In this hydraulic drive device, by selecting the third work mode, it is possible to perform operation with lower fuel consumption than in the second work mode.

  A hydraulic drive device according to a fourth invention is the hydraulic drive device of the second or third invention, further comprising a traveling device driven by an engine, and the working condition is that the traveling device is driven. .

  In this hydraulic drive device, when the traveling device is driven even when the second work mode is selected, which has better fuel economy than the first work mode, that is, the workability is lower than the first work mode. In the first operation mode, the engine and the hydraulic pump are controlled. For this reason, the output shortage at the time of driving | running | working can be suppressed. In particular, since driving the traveling device requires more fuel than other operations, switching to the first work mode when the traveling device is driven is effective in improving workability.

  A hydraulic drive device according to a fifth invention is the hydraulic drive device according to any one of the second invention to the fourth invention, wherein the control unit does not include the first work mode and performs the second work mode and the third work mode. A first storage unit configured to store a work mode selected by the selection device from the plurality of work modes included; Further, the selection device can select a non-energy saving work mode and an energy saving work mode. The control unit operates in the first work mode when the non-energy saving work mode is selected, and operates in the work mode stored in the first storage unit when the energy saving work mode is selected. I do.

  In this hydraulic drive device, one work mode selected from a plurality of work modes including the second work mode and the third work mode is stored, and from the next time, it is stored last time by selecting the energy saving work mode. The engine and hydraulic pump are controlled in different working modes. For this reason, the operation mode selection operation can be simplified.

  A hydraulic drive device according to a sixth invention is the hydraulic drive device according to any one of the first to fifth inventions, wherein the control unit includes a second storage unit and a third storage unit. The second storage unit includes a first engine output torque characteristic corresponding to the first work mode, and a second engine output torque corresponding to the second work mode and having a maximum output torque in a full load region different from the first engine output torque characteristic. The characteristics are stored. The third storage unit includes a first pump absorption torque characteristic corresponding to the first work mode, a second pump absorption torque characteristic corresponding to the second work mode, and a third pump absorption torque characteristic corresponding to the third work mode. Is stored. Then, the control unit has a first matching point where the first engine output torque characteristic and the first pump absorption torque characteristic match, and a second matching point where the second engine output torque characteristic and the second pump absorption torque characteristic match. And a third matching line that is located on the lower rotation side than the regulation line of the second engine output torque characteristic and a third matching point at which the third pump absorption torque characteristic matches, and in the first working mode, the first matching point is set. The engine and the hydraulic pump are controlled so that the engine output torque matches the hydraulic pump absorption torque at the matching point. In the second operation mode, the engine output torque and the hydraulic pump absorption torque are the second matching point. The engine and hydraulic pump are controlled to match, and the third machin Controlling the engine and the hydraulic pump so that the absorption torque of the output torque and the hydraulic pump of the engine coincide at point.

  In the conventional hydraulic drive device, when a plurality of matching points corresponding to a plurality of work modes are set, each matching point is set by the same kind of setting method. For example, each matching point is set by switching the regulation line of the engine output torque line. Alternatively, each matching point is set by switching the pump absorption torque line.

  However, in this hydraulic drive device, the second matching point is set by switching the engine output torque characteristic and the pump absorption torque characteristic that are different in the maximum output torque in the entire load region. The third matching point is set by switching the regulation line of the engine output torque characteristic and switching of the pump absorption torque characteristic. Thus, in this hydraulic drive device, different types of setting methods are used in setting a plurality of matching points. Thereby, a matching point more suitable for each work mode can be set.

  A hydraulic drive apparatus according to a seventh aspect includes an engine, a hydraulic pump, a hydraulic actuator, a selection device, and a control unit. The hydraulic pump is driven by the engine. The hydraulic actuator is operated by pressure oil discharged from a hydraulic pump. The selection device allows the operator to select from among a plurality of work modes including a first work mode, a second work mode having better fuel efficiency than the first work mode, and a third work mode having better fuel efficiency than the second work mode. An apparatus for selecting a desired work mode. The control unit controls the engine and the hydraulic pump according to the work mode selected by the selection device, and when the predetermined work condition is satisfied in the second work mode, the work has a higher output than the second work mode. The operation is switched to the operation in the mode, and the operation in the third operation mode is maintained in the third operation mode even if the operation condition is satisfied.

  In the hydraulic drive device, when the second work mode is selected, the work mode is switched to a work mode having a higher output than the second work mode when a predetermined work condition is satisfied. Therefore, the work can be performed in a work mode suitable for the work conditions, and workability can be improved. In addition, when the user does not want to automatically switch to a work mode having a higher output than the second work mode, the third work mode can be selected regardless of the work conditions by selecting the third work mode. Driving can be continued and fuel consumption can be improved. Thereby, in this hydraulic drive device, according to the user's needs, workability suitable for each operation site can be provided and fuel efficiency can be improved.

  In the hydraulic drive device, when the second work mode is selected, the first work mode is automatically switched when a predetermined work condition is satisfied. Therefore, the work can be performed in a work mode suitable for the work conditions. If the user does not want to automatically switch from the second work mode to the first work mode, selecting the third work mode allows the user to operate in the third work mode regardless of the work conditions. You can continue. Thereby, in this hydraulic drive device, according to the user's needs, workability suitable for each operation site can be provided and fuel efficiency can be improved.

<Configuration>
<overall structure>
FIG. 1 shows a hydraulic excavator 1 which is an embodiment of a hydraulic drive device according to the present invention. The hydraulic excavator 1 includes a lower traveling body 2 including a traveling device 2b driven by a traveling hydraulic motor 2a, a turning device 3 driven by a turning hydraulic motor 3a, and a lower portion via the turning device 3. An upper swing body 4 disposed on the traveling body 2, a work machine 5 attached to a front center position of the upper swing body 4, and a cab provided at a front left position of the upper swing body 4. 6.

  Here, in the work machine 5, the boom 7, the arm 8, and the bucket 9 are connected in order from the upper swing body 4 side so as to be rotatable, and correspond to each of the boom 7, the arm 8, and the bucket 9. Hydraulic cylinders (boom cylinder 10, arm cylinder 11 and bucket cylinder 12) are arranged. Further, on both sides of the driver's seat (not shown) in the cab 6, work machine operation levers 13 and 14 (see FIG. 2) for operating the turning operation of the upper swing body 4 and the bending up and down operation of the work machine 5 are arranged. In addition, a pair of traveling operation levers 15 and 15 (see FIG. 2) and a monitor panel 39 (see FIGS. 2 and 3) for operating the traveling operation of the lower traveling body 2 are arranged in front of the driver seat. .

  The hydraulic excavator 1 is provided with a hydraulic circuit 16 as shown in FIG. The hydraulic circuit 16 supplies hydraulic pressure oil discharged from a hydraulic pump 18 driven by an engine 17 via a control valve 19 to a hydraulic actuator 20 (boom cylinder 10, arm cylinder 11, bucket cylinder 12, traveling hydraulic motor 2a. , And is configured to be supplied to and discharged from the turning hydraulic motor 3a). Then, by the operation of the hydraulic circuit 16, the bending operation of the work machine 5, the turning operation of the upper turning body 4, and the running operation of the lower traveling body 2 are performed.

<engine>
The engine 17 is a diesel engine, and a pressure accumulation (common rail) fuel injection device 21 is attached to the engine 17. This fuel injection device 21 is known per se and will not be described in detail. However, the fuel injection device 21 accumulates fuel in the common rail chamber by a fuel pump and injects fuel from the injector by opening and closing an electromagnetic valve. The fuel injection characteristic is determined by a drive signal from the engine controller 22 to the solenoid valve, and an arbitrary injection characteristic from the low speed range to the high speed range of the engine 17 can be obtained. In this hydraulic excavator 1, a so-called electronically controlled injection system is constructed by equipment including a fuel injection device 21, an engine controller 22, and various sensors. In such an electronically controlled injection system, target injection characteristics are mapped with digital values. As a result, engine output torque characteristics as shown in FIG. 9 can be obtained. Here, a fuel dial 23 is provided to set the throttle amount of the engine 17, and a throttle signal (hereinafter referred to as “first throttle signal”) from a potentiometer 23 a attached to the fuel dial 23 is a pump controller 24. Is input. The actual rotational speed of the engine 17 is detected by the rotational speed sensor 25, and the detection signal is input to the engine controller 22 and the pump controller 24, respectively.

<Hydraulic pump>
The hydraulic pump 18 is a variable displacement hydraulic pump driven by the engine 17, and an electric / hydraulic servo mechanism 26 is attached to the hydraulic pump 18. The electric / hydraulic servo mechanism 26 uses a pressure oil discharged from the hydraulic pump 18 to adjust the tilt angle of the swash plate 18 a of the hydraulic pump 18 and a control current from the pump controller 24. And an electromagnetic proportional control valve 28 for controlling the regulator 27. Here, the pump controller 24 reads the set engine speed set by the first throttle signal from the potentiometer 23a attached to the fuel dial 23 and the work mode command signal from the monitor panel 39 which will be described later. In order to read the actual engine speed from the actual engine speed signal from the sensor 25 and increase or decrease the absorption torque of the hydraulic pump 18 in accordance with the deviation between the two engine speeds, the tilt angle of the swash plate 18a of the hydraulic pump 18 is set. The control current value to be controlled is output to the electromagnetic proportional control valve 28. A pressure sensor 29 for detecting the discharge pressure of the hydraulic pump 18 is provided, and a pump discharge pressure signal from the pressure sensor 29 is input to the pump controller 24.

<Operating valve>
The operation valve 19 is an assembly of hydraulic pilot operated directional control valves 30,... 30 provided corresponding to the hydraulic actuator 20, and pilot pressures output from respective pressure reducing valves 33, 34, and 36 described later. A predetermined oil path switching operation is performed by supplying oil to each direction control valve 30.

<Control lever>
The work machine operation levers 13 and 14 are provided with pressure reducing valves 33 and 34 via operation units 31 and 32 for outputting various operation commands corresponding to various lever operations.

  On the other hand, the traveling operation levers 15 and 15 are similarly provided with a pressure reducing valve 36 via an operation unit 35 that outputs various operation commands corresponding to various lever operations.

  Pilot pressure oil from a pilot pump (not shown) is supplied to each pressure reducing valve 33, 34, 36, and each pressure reducing valve 33, 34, 36 uses various types of supplied pilot pressure oil. The pressure is adjusted based on the operation command, and the adjusted pilot pressure oil is output to the operation valve 19. The pilot pressure oil output from the pressure reducing valves 33, 34, and 36 is input to a predetermined pilot pressure oil input port in the operation valve 19, whereby a predetermined oil path switching operation is performed.

  In this way, the turning operation of the upper swing body 4 and the bending and undulating operation of the work implement 5 are performed by the predetermined operation of the work implement operation levers 13 and 14, and the predetermined operation of the travel operation levers 15 and 15 is performed. The traveling operation of the lower traveling body 2 is performed at.

  Further, the operation signals indicating the operation states of the work machine operation levers 13 and 14 and the travel operation levers 15 and 15 are transmitted via hydraulic switches 37,..., 37 attached to the pressure reducing valves 33, 34, 36, respectively. Are input to the pump controller 24. In the present embodiment, there are a total of 12 types of operation signals to be input to the pump controller 24 by predetermined operations of the operation levers 13, 14, 15, and 15 as described below.

(1) A right turn operation signal corresponding to the right turn operation of the upper turn body 4 (2) A left turn operation signal corresponding to the left turn operation of the upper turn body 4 (3) A boom corresponding to the raising operation of the boom 7 Lifting operation signal (4) Boom lowering operation signal corresponding to the lowering operation of the boom 7 (5) Arm dumping operation signal corresponding to the operation of feeding the arm 8 forward (6) Arm excavation corresponding to the operation of pulling the arm 8 forward Operation signal (7) Bucket dump operation signal corresponding to the operation of feeding the bucket 9 forward (8) Bucket excavation operation signal corresponding to the operation of pulling the bucket 9 forward (9) Corresponding to the right forward traveling operation of the lower traveling body 2 (10) A right reverse travel operation signal corresponding to the right reverse travel operation of the lower traveling body 2 (11) A left forward travel operation signal corresponding to the left forward travel operation of the lower travel body 2 No. (12) Left reverse travel operation signal corresponding to the left reverse travel operation of the lower traveling body 2 The operation unit 31 includes an arm dump operation, an arm excavation operation, a bucket dump operation and the like among various lever operations of the work implement operation lever 13. A potentiometer 38 for replacing each operation amount of the bucket excavation operation with an electric signal and outputting it as an arm dump operation amount signal, an arm excavation operation amount signal, a bucket dump operation amount signal and a bucket excavation operation amount signal is attached. The various operation amount signals are input to the pump controller 24.

<Monitor panel>
The monitor panel 39 (selection device) is a device that is disposed in the cab 6 and functions as a setting device for the operator to select a desired work mode from a plurality of work modes. As shown in FIG. 3, the monitor panel 39 includes a screen unit 50 for displaying information and an operation button unit 51 for inputting an operation. The operation button unit 51 includes buttons for selecting various operations, an arrow button for moving a cursor on the screen, a determination button for determining an input, a return button for returning to the full screen, and the like. Also, numbers from 0 to 9 are assigned to the buttons of the operation button unit 51, respectively, and numbers can be input.

  In the screen unit 50, the currently selected work mode is displayed on the basic screen together with the fuel gauge, the water temperature gauge, and the like. Here, the operation button unit 51 includes a P button 52 for selecting a power mode (first work mode, non-energy saving work mode) that emphasizes workability, and an economy mode (energy saving work mode) that emphasizes fuel efficiency. And an E button 53 for selection. When the operator presses the P button 52, the power mode is selected, and the letter “P” is displayed in the corner of the basic screen. When the operator presses the E button 53, the work mode currently set as the economy mode is selected, and the letter “E” is displayed at the corner of the basic screen.

  The operation button unit 51 includes a select switch button 54. When the select switch button 54 is pressed, the basic screen is switched to the user menu screen shown in FIG. On the user menu screen, a plurality of user menus including “E mode adjustment” are displayed. When “E mode adjustment” is selected here, the screen is switched to the E mode adjustment screen shown in FIG.

  On the E mode adjustment screen, one work mode can be selected from the normal economy mode (second work mode), the first economy mode (third work mode), the second economy mode, and the third economy mode. As described above, in the monitor panel 39, the operator can select the economy mode by pressing the E button 53. The economy mode includes the above four work modes, and is executed as the economy mode. Can be set on the E-mode adjustment screen. The E mode adjustment screen displays “E0” indicating the normal economy mode, “E1” indicating the first economy mode, “E2” indicating the second economy mode, and “E3” indicating the third economy mode, Selection is possible by moving the cursor 55 and pressing the enter key. The work mode selected here is set and stored as an economy mode selected by the E button 53. Of these four work modes selected as the economy mode, the economy mode has the lowest output, instead of the highest output. The first economy mode has better fuel economy than the normal economy mode, the second economy mode has better fuel economy than the first economy mode, and the third economy mode has better fuel economy than the second economy mode. In these work modes, the better the fuel efficiency, the smaller the output, and the higher the output, the worse the fuel efficiency.

<Engine / hydraulic pump control device>
As shown in FIG. 2, the hydraulic excavator 1 is provided with an engine / hydraulic pump control device 40 (control unit) for controlling the operation of the hydraulic circuit. The engine / hydraulic pump control device 40 mainly includes an engine controller 22 (second storage unit), a pump controller 24 (first storage unit, third storage unit), various sensors, and various setting devices.

[Pump controller]
As shown in FIG. 6, the pump controller 24 includes a work condition determination unit 41, a pump absorption torque command control unit 42, a control current command control unit 43, and a throttle command control unit 44.

  A first throttle signal from a potentiometer 23 a attached to the fuel dial 23 and a work mode command signal from the monitor panel 39 are input to the work condition determination unit 41 via a throttle command control unit 44 described later. Furthermore, various operation signals from each hydraulic switch 37, various operation amount signals from a potentiometer 38 attached to the operation unit 31, and a pump discharge pressure signal from the pressure sensor 29 are input to the work condition determination unit 41. Is done. The work condition discriminating unit 41 discriminates the current work condition based on these input signals, and uses the discrimination result as the work condition signal (“a” / “b”) as a pump absorption torque command control unit 42 and a throttle described later. Each is output to the command control unit 44. The processing procedure up to the determination of the work condition by the work condition determination unit 41 will be described in detail later.

  The pump absorption torque command control unit 42 receives the actual engine speed signal from the speed sensor 25 and the work condition signal from the work condition determination unit 41. The pump absorption torque command control unit 42 stores a plurality of pump absorption torque characteristics (see FIG. 7) that are set based on work conditions and work modes. Each pump absorption torque characteristic is obtained by associating torque absorbed by the hydraulic pump 18 from the engine 17 (hereinafter simply referred to as “absorption torque”) and the engine speed. Here, five pump absorption torque characteristics from the first pump absorption torque characteristic to the fifth pump absorption torque characteristic are set. The first pump absorption torque characteristic corresponds to the power mode and the working condition “a”, and is indicated by a line PLa in the drawing. The second pump absorption torque characteristic corresponds to the working condition “b” and the normal economy mode, and is indicated by a line PLb in the drawing. The third pump absorption torque characteristic corresponds to the first economy mode and is indicated by a line PLc in the drawing. The fourth pump absorption torque characteristic corresponds to the second economy mode and is indicated by a line PLd in the drawing. The fifth pump absorption torque characteristic corresponds to the third economy mode and is indicated by the line PLe in the drawing. These pump absorption torque lines PLa-PLe have the same maximum torque and the same minimum torque, but the monotonically increasing regions between the minimum torque and the maximum torque are different, and the first pump absorption torque is different. The line PLa is located on the highest rotation side, and the fifth pump absorption torque line PLe is located on the lowest rotation side.

  In this pump absorption torque command control unit 42, the pump is determined based on the pump absorption torque line selected based on the work condition signal and the work mode command signal and the actual engine speed signal from the speed sensor 25. An absorption torque command value is output. Now, for example, when the power mode is selected, the work condition discriminated by the work condition discriminating unit 41 is the work condition “a”, and the actual engine speed is Na, the first pump absorption torque line PLa is selected. In addition, a pump absorption torque value Ta corresponding to the engine speed Na is output as a pump absorption torque command value. Further, when the normal economy mode is selected, the work condition determined by the work condition determination unit 41 is the work condition “b”, and the actual engine speed is Nb, the second pump absorption torque line PLb is selected. In addition, a pump absorption torque value Tb corresponding to the engine speed Nb is output as a pump absorption torque command value. When the first economy mode is selected and the actual engine speed is Nc, the third pump absorption torque line PLc is selected, and the pump absorption torque value Tc corresponding to the engine speed Nc is the pump absorption torque command. Output as a value. When the second economy mode is selected and the actual engine speed is Nd, the fourth pump absorption torque line PLd is selected, and the pump absorption torque value Td corresponding to the engine speed Nd is determined by the pump absorption torque command. Output as a value. When the third economy mode is selected and the actual engine speed is Ne, the fifth pump absorption torque line PLe is selected, and the pump absorption torque value Te corresponding to the engine speed Ne is absorbed by the pump. Output as torque command value.

  A pump absorption torque command value from the pump absorption torque command control unit 42 is input to the control current command control unit 43. Further, the control current command control unit 43 stores a control current value to the electromagnetic proportional control valve 28 corresponding to the pump absorption torque command value. The control current command control unit 43 outputs a control current value determined based on the pump absorption torque command value from the pump absorption torque command control unit 42 toward the electromagnetic proportional control valve 28. Yes. Now, for example, as shown in FIG. 8, when the pump absorption torque command value from the pump absorption torque command control unit 42 is Ta, the control current value Ia corresponding to the pump absorption torque command value Ta is an electromagnetic proportional control valve. It is output toward 28. When the pump absorption torque command value from the pump absorption torque command control unit 42 is Tb, the control current value Ib corresponding to the pump absorption torque command value Tb is output toward the electromagnetic proportional control valve 28. Similarly, a control current value Ic is output for the pump absorption torque command value Tc, a control current value Id is output for the pump absorption torque command value Td, and a control current value Ie is output for the pump absorption torque command value Te.

  The throttle command control unit 44 receives a work mode command signal from the monitor panel 39, a first throttle signal from a potentiometer 23 a attached to the fuel dial 23, and a work condition signal from the work condition determination unit 41. It has become. The throttle command control unit 44 determines a second throttle signal based on these input signals, and outputs the determined second throttle signal to the engine controller 22. Now, for example, if the fuel dial is set to the maximum position (FULL position), the first throttle signal “FULL” having a magnitude indicating NA as the set engine speed is input to the throttle command control unit 44. In this state, when the work mode command signal input to the throttle command control unit 44 is the power mode command signal “A”, the second throttle signal “NA” having a magnitude indicating NA as the set engine speed is set. Output from the throttle command control unit 44 toward the engine controller 22. When the set position of the fuel dial 23 is the same and the work mode command signal input to the throttle command control unit 44 is the normal economy mode command signal “B”, the set engine speed is set to NB (NB <NA <NA). ) Is output from the throttle command control unit 44 to the engine controller 22. When the work mode command signal input to the throttle command control unit 44 is the first economy mode command signal “C”, the second throttle signal “L” having a magnitude indicating NC (NC <NB) as the set engine speed. NC ”is output from the throttle command control unit 44 to the engine controller 22. Similarly, for the second economy mode command signal “D”, the second throttle signal “ND” having a magnitude indicating ND (ND <NC) as the set engine speed, and the third economy mode command signal “E”. On the other hand, the second throttle signal “NE” having a magnitude indicating NE (NE <ND) as the set engine speed is output.

  Further, for example, when the first throttle signal “FULL”, the power mode command signal “A”, and the work condition signal “a” are input to the throttle command control unit 44, the second throttle signal “NA”. Is output from the throttle command control unit 44 to the engine controller 22. When the first throttle signal “FULL”, the power mode command signal “A”, and the work condition signal “b” are input to the throttle command control unit 44, the second throttle signal “NA” is Output from the command control unit 44 toward the engine controller 22. When the first throttle signal “FULL”, the normal economy mode command signal “B”, and the work condition signal “a” are input to the throttle command control unit 44, the second throttle signal “NA” is Output from the throttle command control unit 44 toward the engine controller 22. When the first throttle signal “FULL”, the normal economy mode command signal “B”, and the work condition signal (b) are input to the throttle command control unit 44, the second throttle signal “NB” is the throttle command. Output from the control unit 44 to the engine controller 22.

[Engine controller]
The engine controller 22 receives a second throttle command signal from the throttle command control unit 44. As shown in FIG. 9, a plurality of engine output torque characteristics having different maximum output torques in the entire load region are mapped and stored in the engine controller 22. In the present embodiment, the first engine output torque characteristic indicated by the line ELa in the figure having the first regulation line Ra is set corresponding to the second throttle command signal “NA”, and the second throttle command signal is set. Corresponding to “NB”, the second engine output torque characteristic indicated by the line ELb in the figure having the second regulation line Rb is set. Further, the third regulation line Rc is set in the second engine output torque line ELb in response to the second throttle command signal “NC”. Corresponding to the second throttle command signal “ND”, the fourth regulation line Rd is set in the second engine output torque characteristic ELb. The regulation line Re is set in the engine output torque line ELb in response to the second throttle command signal “NE”. Of the regulation lines Ra, Rb, Rc, Rd, and Re, the regulation line Ra is positioned on the highest rotation side, and the regulation lines Rb, Rc, Rd, and Re are sequentially on the lower rotation side than the regulation line Ra. Are lined up. The engine controller 22 obtains the fuel injection amount by referring to the actual engine speed signal and the fuel injection characteristic map (not shown) based on the engine output torque lines ELa, ELb, Ra-Re, A drive signal “FF” that satisfies the obtained fuel injection amount is output to the fuel injection device 21.

<Control flow>
Next, a control flow of the hydraulic excavator 1 performed by the engine / hydraulic pump control device will be described.

<Work mode selection process>
As described above, the operator can select a work mode by operating the monitor panel 39. The processing procedure for selecting the work mode will be described with reference to FIG. The symbol “S” in the figure represents a step.

  S1 to S4: In a state where the E mode adjustment screen is displayed on the monitor panel 39, any one of “E0” to “E3” is accepted (S1). Here, when any one of “E1” to “E3” is selected, the selected operation mode from “E1” to “E3” is stored in the pump controller 24 (S2) and selected. The pump absorption torque line PLc-PLe and the engine output torque characteristic regulation line Rc-Re corresponding to the work mode (E1-E3) are set (S3), and the process proceeds to S5. If “E0” is selected in S1, “E0” is stored in the pump controller 24 (S4), and the process proceeds to the work condition determination flowchart shown in FIG. In the initial state when the hydraulic excavator 1 is shipped, “E0” is stored in the pump controller 24.

  S5 to S7: Selection of the power mode or the economy mode is accepted in the state where the basic screen is displayed on the panel monitor (S5). When the operator presses the E button 53 to select the economy mode, the operation is performed in one of the operation modes “E1” to “E3” stored in the pump controller 24 (S6). In S5, when the operator presses the P button 52 to select the power mode, the process proceeds to the work condition determination flowchart shown in FIG.

<Processing procedure for determining work conditions>
Next, a processing procedure for determining work conditions will be described with reference to FIG. The determination of the working condition is executed when the normal economy mode or the power mode is selected.

  S21 to S26: It is determined whether or not the work implement operation levers 13 and 14 and the travel operation levers 15 and 15 are in a neutral state (S21). When the work machine operation levers 13 and 14 and the travel operation levers 15 and 15 are in the neutral state, it is determined that the work condition is “b” (S22). When it is determined that the work implement operating levers 13 and 14 and the traveling operation levers 15 and 15 are not in the neutral state, it is determined whether or not the traveling operation is being performed (S23). If it is determined that the traveling operation is being performed, it is determined that the work condition is “a” (S24). When it is determined that the traveling operation is not performed, it is determined whether or not the work mode is the power mode (S25). When the work mode is the power mode, it is determined that the work condition (a) is satisfied (S24). When the work mode is not the power mode, that is, when the work mode is the normal economy mode, it is determined whether or not the turning operation of the upper swing body 4 is performed (S26).

  S27 to S28: If it is determined in step S26 that the turning operation of the upper swing body 4 is not performed, it is determined whether or not the arm 8 and the bucket 9 are operated (S27). When it is determined that the arm 8 and the bucket 9 are not operated, it is determined that the work condition is “b” (S22). When the arm 8 and the bucket 9 are operated, the discharge pressure (load pressure) P of the hydraulic pump 18 is equal to or higher than the predetermined pressure Pr, and the operation amount S of the lever operation related to the operation of the arm 8 and the bucket 9 is given. It is determined whether or not it is equal to or greater than the fixed amount Sr (S28). When P ≧ Pr and S ≧ Sr, it is determined that the work condition is “a” (S24). If P <Pr and S <Sr, it is determined that the work condition is “b” (S22).

  S29 to S30: When it is determined in step S26 that the turning operation of the upper swing body 4 is being performed, it is determined whether or not the boom 7 is being lowered (S29). When the lowering operation of the boom 7 is performed, it is determined that the work condition is “b” (S22). When the lowering operation of the boom 7 is not performed, it is determined whether or not the raising operation of the boom 7 is performed (S30). When the raising operation of the boom 7 is not performed, it is determined that the work condition is “b” (S22). When the raising operation of the boom 7 is performed, it is determined that the work condition is “a” (S24).

<Operation when working mode is selected>
Next, the operation of the excavator 1 when the work mode is selected will be described below with reference to FIGS. Here, FIG. 12 is a characteristic diagram showing the relationship between the output torque of the engine and the absorption torque of the hydraulic pump, and FIG. 13 shows only the matching points in FIG. FIG. 14 shows time charts of various command values in one work example.

  In this working example, the earth and sand is excavated, the excavated earth and sand is poured into the bucket 9, the upper swing body 4 is turned while raising the boom 7, and the earth and sand in the bucket 9 is loaded on the dump truck, and then the boom 7 It is assumed that the vehicle is turned while lowering to return to the initial state and one work cycle is completed. In this working example, the fuel dial 23 is set at the FULL position.

<Operation when normal economy mode is selected>
When the normal economy mode is selected, control is performed in which the matching points are changed according to the work conditions. Hereinafter, the operation in this case will be described mainly with reference to FIGS.

  Work is started at time t1, and earth excavation operation is started. Here, the work condition determination unit 41 determines that the work condition is the work condition “b” before the work starts and immediately after the work starts. Accordingly, the engine 17 is operated based on the second engine output torque line ELb, and the second pump absorption torque line PLb is selected as the absorption torque characteristic of the hydraulic pump 18, and the second engine output torque line ELb, At the output torque point Mb (second matching point Mb) specified by the pump absorption torque line PLb, the output torque of the engine 17 and the absorption torque of the hydraulic pump 18 are matched, and the output of the engine 17 and the output of the hydraulic pump 18 are matched. Are suppressed respectively. Thereby, useless fuel consumption as a total amount is reduced.

  It is detected that the operation amount of the lever operation related to the operation of the arm 8 and the bucket 9 is greater than or equal to the predetermined amount Sr at time t2, and then the discharge pressure (load pressure) of the hydraulic pump 18 is greater than or equal to the predetermined pressure Pr at time t3. Is detected, the work condition determination unit 41 determines that the work condition is the work condition “a” at time t3. In response to this determination result, the throttle command control unit 44 gradually increases the second throttle signal from NB to NA between times t3 and t4, and in response to the determination result, the control current command control unit 43 starts from time t3. During t4, the control current is gradually decreased from Ib to Ia. As a result, the second engine output torque line ELb corresponding to the work condition “b” is switched to the first engine output torque line ELa corresponding to the work condition “a” and the second pump corresponding to the work condition “b”. The absorption torque line PLb is switched to the first pump absorption torque line PLa corresponding to the work condition “a”. By this switching operation, the engine speed Na (see FIG. 13) that maximizes the output (horsepower) of the engine 17 when the first engine output torque line ELa is set, and the engine 17 corresponding to the engine speed Na. The output torque of the engine 17 and the absorption torque of the hydraulic pump 18 are matched at an output torque point Ma (first matching point Ma) specified by the output torque Ta. Thereby, the hydraulic pump 18 can absorb the maximum horsepower of the engine 17 effectively, and the excavation operation and the turning / boom raising operation of earth and sand can be performed with high efficiency.

  The work condition determination unit 41 determines that the work condition is the work condition “b” at the moment when the turning / boom raising operation is changed to the turning / boom lowering operation at time t5. In response to the determination result, the throttle command control unit 44 gradually decreases the second throttle signal from NA to NB between times t5 and t6, and the control current command control unit 43 receives the determination result from time t5. During t6, the control current is gradually increased from Ia to Ib. As a result, the first engine output torque line ELa corresponding to the work condition “a” is switched to the second engine output torque line ELb corresponding to the work condition “b”, and the first pump corresponding to the work condition “a”. The absorption torque line PLa is switched to the second pump absorption torque line PLb corresponding to the work condition “b”. By this switching operation, the output torque of the engine 17 and the absorption torque of the hydraulic pump 18 are matched at the second matching point Mb, and the output of the engine 17 and the output of the hydraulic pump 18 are respectively suppressed. Thereby, useless fuel consumption as a total amount is reduced.

  Here, at time (t4 to t5), the pump absorption torque line PLa becomes a characteristic line for increasing / decreasing the absorption torque of the hydraulic pump 18 as the engine speed increases / decreases by the hydraulic pump control device 40. In this way, the absorption torque of the hydraulic pump 18 is controlled, and at the time (t1 to t3) and time (t6 to t7), the hydraulic pump control device 40 causes the pump absorption torque line PLb to increase / decrease the engine speed. The absorption torque of the hydraulic pump 18 is controlled so that the characteristic line increases / decreases the absorption torque of the hydraulic pump 18 as it decreases.

  In the present embodiment, the limit of matching between the output torque of the engine 17 and the absorption torque of the hydraulic pump 18 is in the vicinity of the output torque points Ma and Mb in the engine output torque lines ELa and ELb. It is preferable to match the output torque of the engine 17 and the absorption torque of the hydraulic pump 18 on the low speed side of the engine speeds Na and Nb corresponding to the output torque points Ma and Mb.

<Operation when selecting the first economy mode to the third economy mode>
When one of the work modes from the first economy mode to the third economy mode is selected, unlike the normal economy mode, a constant matching point is set in each economy mode regardless of the work conditions, and the engine and hydraulic pump are controlled. Is done. Hereinafter, the operation in this case will be described mainly with reference to FIG.

  In the first economy mode, the second regulation line Rb of the second engine output torque line ELb corresponding to the work condition “b” in the normal economy mode is switched to the third regulation line Rc corresponding to the first economy mode, and normally The second pump absorption torque line PLb corresponding to the work condition “b” in the economy mode is switched to the third pump absorption torque line PLc corresponding to the first economy mode. Accordingly, the output of the engine 17 at the output torque point Mc (third matching point Mc) specified by the engine speed Nc (see FIG. 13) and the output torque Tc of the engine 17 corresponding to the engine speed Nc. The torque and the absorption torque of the hydraulic pump 18 are matched.

  Similarly, in the second economy mode, an output torque point Md (fourth matching) specified by the engine speed Nd (see FIG. 13) and the output torque Td of the engine 17 corresponding to the engine speed Nd. Matching is performed at point Md). Similarly, in the third economy mode, the output torque point Me (the fifth matching point Me) specified by the engine speed Ne (see FIG. 13) and the output torque Te of the engine 17 corresponding to the engine speed Ne. ).

  The third regulation line Rc is located on the lower rotation side than the second regulation line Rb, the fourth regulation line Rd is located on the lower rotation side than the third regulation line Rc, and the fifth regulation line Re is located on the lower rotation side than the fourth regulation line Rd. The same applies to the pump absorption torque line PLb-PLe. Therefore, as shown in FIG. 13, Na> Nb> Nc> Nd> Ne and Ta> Tb> Tc> Td> Te. Accordingly, the first matching point Ma has the highest output among the matching points Ma to Me, and the absorption horsepower at the hydraulic pump is large. And output becomes small in order of Ma-Me, and fuel consumption is small.

  As a result, in the first economy mode to the third economy mode, low output operation is maintained and fuel consumption is reduced.

<Features>
(1)
In the hydraulic excavator 1, an operator can select a desired operation mode from among a power mode, a normal economy mode, a first economy mode, a second economy mode, and a third economy mode. When the power mode is selected, workability can be improved by setting the high-output first matching point Ma. When the normal economy mode is selected, the matching point is changed to either the first matching point Ma or the second matching point Mb according to the change of the work condition. It is possible to optimally control the output, thereby eliminating fuel consumption as a total amount and improving fuel efficiency. Further, when it is not necessary to change the output and it is desired to maintain the low output operation, the low output third matching point Mc is set by selecting the first economy mode, and the fuel consumption can be further improved. Further, when it is desired to maintain a low-power operation, the fuel economy can be further improved by selecting the second economy mode or the third economy mode.

  As described above, in the hydraulic excavator 1, not only the normal economy mode but also a plurality of work modes having different matching points such as the first economy mode, the second economy mode, and the third economy mode are prepared in the economy mode. And can be selected according to user preference. For this reason, according to a user's needs, the work mode which has workability | operativity suitable for each operation site can be selected. Thereby, fuel consumption can be suppressed and fuel consumption can be improved.

  Further, in the conventional excavator, when it is desired to suppress the output as compared with the normal economy mode, the fuel consumption is adjusted by lowering the engine speed with the throttle dial, but in the excavator 1 according to the present invention, Therefore, it is not necessary to make such adjustment using the throttle dial, and it is only necessary to change the work mode on the monitor panel 39. For this reason, a fuel consumption can be improved by simple operation.

(2)
In the hydraulic excavator 1, one work mode selected from the normal economy mode, the first economy mode, the second economy mode, and the third economy mode is stored as the economy mode. By simply selecting the mode, the engine and the hydraulic pump are controlled in the work mode selected last time. For example, when the first economy mode is selected, from the next time, unless the work mode is selected again on the E mode adjustment screen, the operation is performed in the first economy mode when the E button 53 is pressed. Thereby, the operation mode selection operation can be simplified.

(3)
In the hydraulic excavator 1, the switching between the first matching point Ma and the second matching point Mb is set by switching the engine output torque lines ELa and ELb and switching the pump absorption torque characteristics PLa and PLb. On the other hand, switching between the matching points Mb-Me from the second matching point Mb to the fifth matching point Me is performed by switching the regulation line Rb-Re of the engine output torque line PLb and the pump absorption torque characteristic PLb-PLe. And switching. Thus, in this hydraulic drive device, the first matching point Ma and the second matching point Mb and the third matching point Mc to the fifth matching point Me are set by different setting methods. Thereby, a matching point more suitable for each work mode can be set.

<Other embodiments>
(A)
In the above embodiment, four work modes are provided as the economy mode, but the number of work modes is not limited to this, and may be increased or decreased.

  Moreover, in said embodiment, although work modes other than economy mode are only power modes, other work modes may be provided.

(B)
In the above-described embodiment, the work condition is determined by whether or not the traveling operation is performed, whether or not the turning operation is performed, whether or not the arm 8 and the bucket 9 are operated, the operation amount S of the lever operation, and whether the boom 7 is lowered or raised. However, it may be determined based on a condition different from this. For example, the hydraulic actuator 20 may be replaceable, and the type of the hydraulic actuator to be attached may be used to determine the working condition.

(C)
In the above embodiment, when the normal economy mode is selected, the matching points are automatically switched based on the determination of the working conditions. However, the normal economy mode is not used, but another economy mode (for example, the first economy mode). The matching points may be automatically switched when is selected. For example, when the first economy mode is selected, automatic switching may be performed between the matching point Mc and the matching point Ma.

  Further, not only the normal economy mode but also another economy mode (for example, the first economy mode) may be selected, and automatic switching of matching points may be performed. For example, when the normal economy mode is selected, automatic switching is performed between the second matching point Mb and the first matching point Ma, and when the first economy mode is selected, the third matching point is selected. Automatic switching may be performed between Mc and the second matching point Mb.

(D)
In the above embodiment, in the normal economy mode, when the predetermined work condition is satisfied, the low-power operation is switched to the high-power operation. However, when the predetermined work condition is satisfied, the high-power operation is switched. The operation may be switched from the output operation to the low output operation. In addition, multiple work modes are provided in the power mode, and a mode that switches from high-power operation to low-power operation according to work conditions and a mode that maintains high-power operation regardless of work conditions are selected. It may be possible.

(E)
In the above embodiment, when the work condition “a” is satisfied in the normal economy mode, the same matching point Ma as that in the power mode is set. However, from the viewpoint of improving workability, the matching point Ma is not necessarily set. Need not be set, and a matching point whose output is higher than the matching point Mb under the work condition “b” in the normal economy mode may be set.

  INDUSTRIAL APPLICABILITY The present invention is useful as a hydraulic drive device because it can provide workability suitable for each operation site according to user needs and has an effect of improving fuel consumption.

External view of a hydraulic excavator. Configuration diagram of hydraulic circuit The front view of a monitor panel. The figure which shows a user menu screen. The figure which shows an E mode adjustment screen. The control block diagram of an engine and a hydraulic pump control apparatus. The graph showing a pump absorption torque characteristic. The graph which shows the control current value corresponding to a pump absorption torque command value. The graph showing an engine output torque characteristic. The flowchart which shows the process sequence of selection of a work mode. The flowchart which shows the process sequence of work condition discrimination | determination. The graph which shows the setting method of a matching point. The figure which shows the matching point set in FIG. Time chart of various command values in one work example Explanatory drawing of a prior art. Explanatory drawing of a prior art.

Explanation of symbols

1 Hydraulic excavator (hydraulic drive)
2b Traveling device 17 Engine 18 Hydraulic pump 20 Hydraulic actuator 22 Engine controller (second storage unit)
24 Pump controller (first storage unit, third storage unit)
39 Monitor panel (selection device)
40 Engine / Hydraulic Pump Control Device (Control Unit)

Claims (7)

Engine,
A hydraulic pump driven by the engine;
A hydraulic actuator operated by pressure oil discharged from the hydraulic pump;
A selection device for an operator to select a desired work mode from a plurality of work modes including a first work mode, a second work mode, and a third work mode, each of which has a different fuel consumption in the engine;
The engine and the hydraulic pump are controlled according to the work mode selected by the selection device, and when a predetermined work condition is satisfied in the second work mode, the operation in the first work mode is performed. Switching, in the third work mode, a control unit that maintains operation in the third work mode even if the work conditions are satisfied;
A hydraulic drive device comprising: The one work mode is a work mode in which the absorption horsepower in the hydraulic pump is larger than that in the second work mode and the third work mode,
The second work mode and the third work mode are work modes in which fuel consumption in the engine is better than in the first work mode.
The hydraulic drive device according to claim 1. The third work mode is a work mode in which the absorption horsepower in the hydraulic pump is smaller than that in the second work mode and fuel consumption is good in the engine.
The hydraulic drive device according to claim 2. It further comprises a traveling device driven by the engine,
The working condition is that the traveling device is driven.
The hydraulic drive device according to claim 2 or 3. The control unit stores a work mode selected by the selection device from a plurality of work modes not including the first work mode and including the second work mode and the third work mode. Have
In the selection device, it is possible to select a non-energy saving work mode and an energy saving work mode,
The control unit performs the operation in the first work mode when the non-energy saving work mode is selected, and the work stored in the first storage unit when the energy saving work mode is selected. Operate in mode,
The hydraulic drive device according to claim 2. The controller is
A first engine output torque characteristic corresponding to the first work mode and a second engine output torque characteristic corresponding to the second work mode and having a maximum output torque in a full load region different from the first engine output torque characteristic are stored. A second storage unit,
A first pump absorption torque characteristic corresponding to the first operation mode, a second pump absorption torque characteristic corresponding to the second operation mode, and a third pump absorption torque characteristic corresponding to the third operation mode are stored. A third storage unit;
Have
A first matching point where the first engine output torque characteristic and the first pump absorption torque characteristic match; a second matching point where the second engine output torque characteristic and the second pump absorption torque characteristic match; A third regulation line located on the lower rotation side than the regulation line of the two engine output torque characteristics and a third matching point at which the third pump absorption torque characteristics coincide with each other; The engine and the hydraulic pump are controlled so that the output torque of the engine matches the absorption torque of the hydraulic pump at one matching point, and the output torque of the engine at the second matching point in the second work mode. And the hydraulic pump so that the absorption torque of the hydraulic pump matches Controls, and absorption torque of the hydraulic pump and the output torque of the engine is said to control the engine and the hydraulic pump to coincide in the third matching point in the third working mode,
The hydraulic drive device according to claim 1. Engine,
A hydraulic pump driven by the engine;
A hydraulic actuator operated by pressure oil discharged from the hydraulic pump;
An operator may select a desired one of a plurality of work modes including a first work mode, a second work mode having better fuel efficiency than the first work mode, and a third work mode having better fuel efficiency than the second work mode. A selection device for selecting a working mode;
The engine and the hydraulic pump are controlled in accordance with the work mode selected by the selection device, and when a predetermined work condition is satisfied in the second work mode, the output is higher than that in the second work mode. Switching to operation in a high work mode, and in the third work mode, a controller that maintains operation in the third work mode even if the work conditions are satisfied;
A hydraulic drive device comprising:

Images