JP2001295675A - Hydraulic traveling vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve operational efficiency by inhibiting an automatic idling function, when the rotating speed is controlled by an accelerator pedal during operation. SOLUTION: When all operating lever BL and the like are not completely operated for more than a prescribed time during operation, the engine rotating speed set by a fuel lever 66a is reduced to idling rotating speed. In operational acceleration, when an accelerator pedal 51 is actuated, the automatic idling function is inhibited. Accordingly, in the case where the engine rotating speed is controlled to a desired rotating speed by the accelerator pedal 51, the engine rotating speed will not be reduced to the idling rotating speed, even if the operating lever BL and the like are not completely operated more than the prescribed time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic traveling vehicle such as a wheel hydraulic excavator having an automatic idle function.

[0002]

2. Description of the Related Art A wheel-type hydraulic excavator adjusts an engine speed with an accelerator pedal, and adjusts a direction and a flow rate of pressure oil from a variable displacement hydraulic pump with a traveling control valve to rotate a traveling hydraulic motor. This moves forward,
Controls reverse and vehicle speed. Such a wheel-type hydraulic excavator is equipped with a work accelerator function for adjusting the engine rotation speed by an accelerator pedal during work, and when the work actuator and the travel actuator are not operated for a predetermined time or more, the engine rotation is performed. An automatic idle function for reducing the number to a predetermined idle speed is mounted.

The operation / non-operation of the working actuator and the traveling actuator is detected by operating / non-operating the control valve of each actuator. That is, a route is provided for guiding the pressure oil from the pilot pump to the tank via each control valve. If so, it can be determined that one of the control valves is being operated.

[0004]

In such a conventional wheel-type hydraulic excavator, the traveling control valve is detected to be non-operating at the time of a working accelerator.
Even when the engine speed is rotating at a predetermined speed higher than the idle speed by depressing the accelerator pedal,
If all the operation levers are not operated for a predetermined time or more, the engine speed is automatically reduced to the idle speed, which may give the driver a sense of discomfort. This is because the conditions of the auto idle are not set in detail according to the application.

[0005] It is an object of the present invention to provide a hydraulic traveling vehicle having improved operability by prohibiting an auto-idle function when the rotation speed is adjusted by an accelerator pedal during work. Another object of the present invention is to provide a hydraulic traveling vehicle capable of setting a highly versatile auto idle function by switching auto idle conditions according to the intended use of the hydraulic traveling vehicle.

[0006]

The present invention will be described with reference to the drawings of the embodiments. (1) The hydraulic traveling vehicle according to claim 1,
, A traveling hydraulic motor 31 driven by pressurized oil discharged from the variable displacement hydraulic pumps 10, 20, a variable displacement hydraulic pump 10,
A plurality of working hydraulic actuators 32 to 35 driven by pressurized oil discharged from the pump 20, an accelerator pedal 51 for adjusting the rotation speed of the traveling hydraulic motor 31, and a prime mover 41 according to at least the amount of depression of the accelerator pedal 51. Rotation speed adjusting means 63 for adjusting the rotation speed of the motor, operating lever means BL for operating a plurality of working hydraulic actuators 32 to 35, respectively, and the prime mover 41 when all of the operating lever means BL have not been operated for a predetermined time or more. Motor rotation speed reduction means 607 for reducing the rotation speed of the motor to a predetermined low rotation speed,
610, 611, and even when all of the operation lever means BL have not been operated for a predetermined time or more, if the operation of the accelerator pedal 51 is detected,
07 prohibiting means 610 for prohibiting the operation of 07, thereby achieving the above-described object. (2) The variable displacement hydraulic pumps 10 and 20 driven by the prime mover 41 and the variable displacement hydraulic pump 1
A traveling hydraulic motor 31 driven by pressure oil discharged from the hydraulic pumps 0 and 20; a plurality of working hydraulic actuators 32 to 35 driven by pressure oil discharged from the variable displacement hydraulic pumps 10 and 20; Accelerator pedal 51 for adjusting the number of revolutions of hydraulic motor 31, pedal detecting means 69 for detecting the operation amount of accelerator pedal 51, pedal detecting means 69
The rotation speed adjusting means 63 for adjusting the rotation speed of the prime mover 41 based on the pedal operation amount detected by the operation, the operation lever means BL for operating each of the plurality of working hydraulic actuators 32 to 35, and the operation lever means BL Lever detecting means 17 for detecting operation, and when the lever detecting means 17 detects that all of the operating lever means BL have not been operated for a predetermined time or more, the rotation speed of the prime mover 41 is reduced to a predetermined low rotation speed. Prime mover speed reduction means 607, 6
10, 611 and when the operation of the accelerator pedal 51 is detected by the pedal detecting means 69, the engine speed reducing means 6
07 prohibiting means 610 for prohibiting the operation of 07, thereby achieving the above-described object. (3) According to a third aspect of the present invention, in the hydraulic traveling vehicle according to the second aspect, the operation lever detecting means 17 includes control valves 12 to 14 for controlling the flow rate and direction of the pressure oil to the working hydraulic actuators 32 to 35. The operation of the operation lever means BL is detected based on the presence or absence of the operation of 21 to 24. (4) The variable displacement hydraulic pumps 10 and 20 driven by the prime mover 41 and the variable displacement hydraulic pump 1
A traveling hydraulic motor 31 driven by pressure oil discharged from the hydraulic pumps 0 and 20; a plurality of working hydraulic actuators 32 to 35 driven by pressure oil discharged from the variable displacement hydraulic pumps 10 and 20; An accelerator pedal 51 for adjusting the rotational speed of the hydraulic motor 31; a rotational speed adjusting means 63 for adjusting the rotational speed of the prime mover 41 according to the operation amount of one of the fuel lever 65a and the accelerator pedal 51; Operating lever means BL for operating each of the hydraulic actuators 32 to 35; motor rotation speed reduction means 607, 610, 611 for reducing the rotation speed of the motor 41 to a predetermined low rotation speed when a predetermined auto idle condition is satisfied;
A first operation performed by adjusting the rotation speed by the fuel lever 65a, and a second operation performed by adjusting the rotation speed by the accelerator pedal 51.
Switching means 607 and 610 for switching the automatic idle condition in accordance with the operation and traveling of the vehicle, thereby achieving the above-mentioned object. (5) In the hydraulic traveling vehicle according to the fourth aspect, in the hydraulic traveling vehicle according to the fourth aspect, the auto-idle condition of the first operation includes that all of the operation lever means BL have not been operated for a predetermined time or more. The auto-idle conditions for work and traveling include that all of the operation lever means BL are not operated and the accelerator pedal 51 is not operated.

(1) In the hydraulic traveling vehicle according to the first to third aspects of the present invention, the prime mover speed reduction means 607, 610, 61
According to 1, if all the operation lever means BL are not operated for a predetermined time or more, the rotation speed of the prime mover is reduced to the predetermined rotation speed, but when the accelerator pedal 51 is depressed,
The operation of the motor rotation speed reducing means 607 is prohibited. (2) In the hydraulic traveling vehicle according to the fourth and fifth aspects of the present invention, the switching means 607, 610 controls the fuel lever 65a.
The auto-idle condition is switched according to the first operation performed by adjusting the rotation speed and the second operation performed by adjusting the rotation speed with the accelerator pedal 51 and traveling. As a result, it is possible to individually set auto idle conditions according to the purpose of use of the hydraulic traveling vehicle.

[0008] In the section of the means for solving the above-mentioned problems, which explains the configuration of the present invention, the drawings of the embodiments are used to make the present invention easy to understand. However, the present invention is not limited to this.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A case where the present invention is applied to a wheel type hydraulic excavator will be described with reference to FIGS. The wheel type hydraulic excavator has a revolving structure mounted on a wheel type traveling structure so as to be revolvable, and a work attachment is attached to the revolving structure.

FIG. 1 shows a hydraulic circuit of a wheel type excavator according to the present invention. The hydraulic circuit includes main pumps 10 and 20 driven by an engine (not shown), four control valves 11 to 14 disposed in series with the main pump 10, and disposed in series with the main pump 20. Five control valves 21 to 25
A traveling motor 31 driven by pressure oil controlled by control valves 11 and 25; a bucket cylinder 32 driven by pressure oil controlled by control valve 12; and a pressure controlled by control valves 13 and 23. Boom cylinder 33 driven by oil
And an arm cylinder 34 driven by pressure oil controlled by the control valves 14 and 22, and a turning motor 35 driven by pressure oil controlled by the control valve 21. Control valve 24
Is a spare control valve. Traveling motor 31,
The boom cylinder 33 and the arm cylinder 34 are driven by a merging circuit in which pressure oil from the main pumps 10 and 20 merges to increase the operating speed. The pilot pump 10A supplies pilot pressure oil to a pilot circuit described later, and also supplies a detection circuit for operating lever operation / non-operation by auto idle control described later.

FIG. 2 is a diagram showing details of the traveling hydraulic circuit shown in FIG. The traveling hydraulic circuit in FIG. 2 shows one main pump 10 and one traveling control valve 11 in FIG. As shown in FIG. 2, a main pump 10 driven by an engine (motor) 41 is provided.
The direction and the flow rate of the oil discharged from the control valve 11 are controlled by the control valve 11, and the counterbalance valve 42
Is supplied to the traveling motor 31 via a brake valve 43 having a built-in. A transmission 44 is connected to an output shaft of the traveling motor 31. The rotation of the traveling motor 31 drives a tire 47 via a transmission 44, a propeller shaft 45, and an axle 46, and the wheel type hydraulic shovel travels.

The displacement volume of the main pump 10 (the amount of tilt)
Is adjusted by the regulator 48 according to the pump discharge pressure. The regulator 48 is provided with a torque limiting section, and the pump discharge pressure is fed back to the torque limiting section to perform so-called horsepower control.

The switching direction and stroke of the control valve 11 are controlled by the pilot pressure from the pilot circuit. The travel speed of the vehicle can be controlled by adjusting the stroke amount. The pilot circuit is a pilot pump 10A also shown in FIG.
And the pilot 2 according to the depression of the accelerator pedal 51
A traveling pilot valve 52 for generating the next pressure, a slow return valve 53 following the pilot valve 52 and delaying the return oil to the pilot valve 52, and a forward / backward / neutral vehicle following the slow return valve 53 And a forward / reverse switching valve 54 for selection. The forward / reverse switching valve 54 is an electromagnetic switching valve that is switched by a forward / backward switch 66 described later. The traveling pilot pressure is detected by a pressure sensor 69 described later.

FIG. 2 shows a state in which the forward / reverse switching valve 54 is neutral (N position) and the traveling pilot valve 52 is not operated.
Is in the neutral position, the pressure oil from the main pump 10 returns to the tank, and the vehicle is stopped. Forward / reverse switching valve 54
Is switched to forward (F position) or reverse (R position) and the accelerator pedal 51 is depressed, a pilot secondary pressure corresponding to the depression amount is generated. Accelerator pedal 51
The pilot pressure generated in proportion to the above operation is output as forward-side pilot pressure oil and reverse-side pilot pressure oil through the forward / reverse switching valve 54, and acts on the pilot port of the control valve 11. Control valve 11
Is switched by a stroke amount according to the pilot pressure.
By switching the control valve 11, the oil discharged from the main pump 10 is guided to the traveling motor 31 via the control valve 11, the center joint 55, and the brake valve 43, and the traveling motor 31 is driven to drive the wheel hydraulic excavator. I do.

The traveling motor 31 is provided with a self-pressure tilt control mechanism. When the driving pressure exceeds a predetermined value, the driving motor 31 is driven at low speed and high torque by increasing the volume as the pressure increases, and the driving pressure decreases. Drive at high speed and low torque as volume decreases. The driving pressure acts on the control piston 58 and the servo piston 59 of the traveling motor 31 from the shuttle valve 56.

When the accelerator pedal 51 is released during traveling, the traveling pilot valve 52 shuts off the pressure oil from the pilot pump 10A, and its outlet port communicates with the tank.
As a result, the pressure oil acting on the pilot port of the control valve 11 returns to the tank via the forward / reverse switching valve 54, the slow return valve 53, and the traveling pilot valve 52. At this time, since the return oil is throttled by the throttle of the slow return valve 53, the control valve 11 is gradually switched to the neutral position. When the control valve 11 is switched to the neutral position, the oil discharged from the main pump 10 returns to the tank and the hydraulic oil
(Drive pressure) supply is cut off and the counterbalance valve 4
2 also switches to the illustrated neutral position.

In this case, the vehicle body continues to travel due to the inertial force of the vehicle body, and the traveling motor 31 changes from a motor operation to a pump operation, and the B port side in FIG. The pressure oil from the travel motor 31 is throttled by the throttle (neutral throttle) of the counter balance valve 42, so that the pressure between the counter balance valve 42 and the travel motor 31 increases and acts as a brake pressure on the travel motor 31. . As a result, the traveling motor 31 generates a braking torque to brake the vehicle body. If the amount of suction oil is insufficient during the operation of the pump, the travel motor 31 is replenished with the amount of oil from the makeup port MP. Brake pressure is relief valve RV
1, RV2 regulates the maximum pressure.

Since the return oil from the relief valves RV1 and RV2 is guided to the suction side of the traveling motor 31, a closed circuit is formed inside the motor during the relief, and the temperature of the hydraulic oil may increase, which may adversely affect equipment. Therefore, a small amount of pressure oil is released from the neutral throttle of the counter balance valve 42 and led to the control valve 11, where the A and B ports are connected (AB communication) in the control valve 11, and the travel motor 31 is sucked again. Form a circulation circuit that returns to the side,
Hydraulic oil temperature is cooling.

When the accelerator pedal 51 is released on a downhill, a hydraulic brake is generated as in the case of deceleration described above.
Go down the hill by inertial running while braking the vehicle. When going downhill,
Even when the accelerator pedal 51 is depressed, the counter balance valve 42 operates to generate a hydraulic brake pressure so as to attain a motor rotation speed (running speed) corresponding to the flow rate of flow from the main pump 10 to the running motor 31.

The work attachment of the wheel type hydraulic excavator includes, for example, a boom, an arm, and a bucket.
The operator's cab is provided with pilot operation levers for arms, booms, and buckets. FIG. 3 shows a boom pilot circuit as a representative of the work attachment pilot circuit. When the boom operation lever BL is operated, the pressure reducing valve (pilot valve) P
The hydraulic pilot switching type boom control valves 13 and 23 (FIG. 1) are switched by the pressure from the pilot pump 10A depressurized by V, and the discharge oil from the main pump 10 is supplied to the boom cylinder via the control valves 13 and 23. The boom is raised and lowered by the expansion and contraction of the boom cylinder 33. When the boom operation lever BL is moved to the boom raising side, the boom raising pilot pressure oil is supplied to the bottom side of the boom cylinder 33, and when the boom lowering side is operated, the boom lowering pilot pressure oil is supplied to the rod side of the boom cylinder 33.

Although not shown in FIGS. 1 and 4, an arm lever, a bucket lever, and a turning lever are provided in addition to the boom operation lever BL and the accelerator pedal 51, and the operation amount of each lever is similar to the boom lever BL. A pressure reducing valve (pilot valve) that discharges pilot pressure oil corresponding to the pressure, a control valve that is switched by the discharged pilot pressure oil, and an actuator that is driven by pressure oil from the control valve.

FIG. 4 is a diagram for explaining a circuit for detecting the operating / non-operating state of the operating lever used for the automatic idle control. Main pumps 10, 20 and pilot pump 10A and control valves 11 to 14, 21 to 2
5 is shown in FIG. Pilot pump 10A
The oil discharged from is supplied via a pipe line L1 to a bucket control valve 12, a boom control valve 13, an arm control valve 14, a swing control valve 21, an arm control valve 22, a boom control valve 23 and a spare. It is led to the tank through the control valve 24. Restriction 1 in line L1
6, and an auto-idle pressure switch 17 is provided downstream of the throttle 16. When any one of the control valves 12 to 14, 21 to 24 is operated, the pressure in the pipe line L1 on the downstream side of the throttle 16 increases, and the pressure switch 17 is turned on to control the control valve.
That is, it is detected that the operation lever has been operated.

FIG. 5 is a block diagram of a control circuit for controlling the engine speed. Each device is controlled by a controller 60 composed of a CPU or the like. The governor 61 of the engine 41 is connected to a pulse motor 63 via a link mechanism 62.
To the engine 4 by the rotation of the pulse motor 63.
The number of rotations of 1 is controlled. That is, the pulse motor 63
The rotation speed increases with forward rotation of the motor, and decreases with reverse rotation. The rotation of the pulse motor 63 is controlled by a control signal from the controller 60. A potentiometer 64 is connected to the governor 61 via a link mechanism 62. The potentiometer 64 detects a governor lever angle corresponding to the rotational speed of the engine 41, and inputs the detected angle to the controller 60 as an engine control rotational speed Nθ. Is done. The controller 60 also has a potentiometer 65 for instructing a target rotation speed FL in accordance with a manual operation of a fuel lever 65a provided in the cab.
, A forward / reverse switch 66 for instructing the forward / reverse switching valve 54 to be switched to the N, F, and R positions, a parking brake switch 67A, a work brake switch 67B, and an auto idle switch 68 for enabling an automatic idle function.
, A pilot pressure sensor 69 for detecting the traveling pilot pressure, and the auto-idle pressure switch 17 shown in FIG.

The parking brake switch 67A is turned on at the time of parking to put the parking brake into an operating state. The work brake switch 67B is turned on at the time of work to put the parking brake and the service brake in an operating state. When running, neither switch is operated, so the parking brake is released,
The service brake is operated by the brake pedal. The fuel lever 65a depends on the operation state of the brake switches 67A and 67B and the forward / reverse selector switch 66.
Normal work performed by adjusting the engine speed (hereinafter, referred to as
It is possible to identify a normal operation), a running operation, and an operation performed by adjusting the rotation speed by an accelerator pedal (hereinafter, referred to as an operation accelerator). FIG. 6 is an identification table, and a work / travel identification circuit 604 in FIG. 7 described later outputs a travel signal and a work accelerator signal in accordance with the logic in FIG.

FIG. 7 is a conceptual diagram illustrating details of the controller 60. The function generator 601 outputs a target engine speed Nt for traveling in proportion to the amount of depression of the accelerator pedal, the function generator 602 outputs a target engine speed Nda for operation in proportion to the amount of depression of the accelerator pedal, and the function generator 603 Outputs a target engine speed Ndl proportional to the operation amount of the fuel lever 65a.

That is, the function generators 601, 602
It outputs a travel target rotation speed Nt and a work accelerator target rotation speed Nda determined by functions (rotation speed characteristics) L1 and L2 in which the pilot pressure Pt detected by the traveling pilot pressure sensor 69 and the target rotation speed of the engine 41 are associated. The function generator 603 outputs a working lever target rotation speed Ndl determined by a function (rotation speed characteristic) L3 that associates a signal FL depending on the operation amount of the fuel lever 65a with a target rotation speed of the engine 41.

The target rotation speed Nt based on the target accelerator running speed characteristic L1 output from the function generator 601 and the target rotation speed Nda based on the working accelerator target rotation speed characteristic L2 output from the function generator 602 are selected. Switch 60
Select with 5. The selection switch 605 is switched by a switching signal from the work / travel identification circuit 604. The work / travel identification circuit 604 includes a forward / reverse switch 66, a parking brake switch 67A, and a work brake switch 67.
A switching signal is input from B. The work / travel discrimination circuit 604 outputs a travel signal when the forward / reverse switch 66 is switched to any of the front and rear positions and both the parking brake switch 67A and the work brake switch 67B are off. The selection switch 605 selects the characteristic L1 based on the traveling signal. The work / travel discrimination circuit 604 outputs a work accelerator signal when the forward / reverse switch 66 is switched to the neutral position and both the parking brake switch 67A and the work brake switch 67B are turned on. The work / travel discrimination circuit 604 includes a forward / reverse switch 66 that is switched to a neutral position, a parking brake switch 67A that is on, and a work brake switch 67 that is turned on.
The work accelerator signal is also output when B is off. The selection switch 605 selects the characteristic L2 based on the work accelerator signal. The target rotation speed selected by the selection switch 605 is input to the maximum value selection circuit 606, and is compared with the target rotation speed Ndl based on the fuel lever characteristic L3 output from the function generator 603. Maximum value selection circuit 606
Selects the larger of the two inputs.

The characteristics L1 to L3 will be described in detail with reference to FIG. The characteristic L1 is a target running speed characteristic suitable for running depending on the amount of depression of the accelerator pedal 51, and the characteristic L2 is a target working speed characteristic suitable for work depending on the amount of pressing of the accelerator pedal 51. Work refers to excavation work using a work attachment. The characteristic L1 has the target rotation speed rising, that is, the slope is steeper than L2, and the idle rotation speed Ntid and the maximum rotation speed Ntmax of the characteristic L1 are higher than the idle rotation speed Ndid and the maximum rotation speed Ndamax of the characteristic L2, respectively. Is set. The characteristic L3 is a work speed characteristic suitable for work depending on the operation amount of the fuel lever 65a. In the characteristics L2 and L3, the inclination, that is, the change amount of the engine speed with respect to the operation amount is made equal, and the idle speed Ndid and the target speed Ndmax for the full operation are also made equal.

In FIG. 7, the target set speed Ny output from the maximum value selection circuit 606 is input to the servo control unit 608 via the changeover switch 607. The changeover switch 607 is switched by an output from the auto idle switching circuit 610, and one of the auto idle target speed Nai from the auto idle speed generating circuit 611 and the target set speed Ny described above is set as the speed command value Nin. Output. The auto idle switching circuit 610 includes an auto idle switch 68, an auto idle pressure switch 17,
The traveling pilot pressure sensor 69 and the target set rotation speed Ny are input from the maximum value selection circuit 606, and the automatic idle changeover switch 607 is switched by an algorithm described later.

From the changeover switch 607, the rotational speed command value Nin
Is output, the rotation speed command value Nin is compared with the control rotation speed Nθ corresponding to the amount of displacement of the governor lever detected by the potentiometer 64 by the servo control unit 608. The pulse motor 63 is controlled to match.

Referring to FIG. 9, first, in step S21, a rotational speed command value Nin and a control rotational speed Nθ are read, respectively.
Proceed to step S22. In step S22, Nθ−N
The result of “in” is stored in the memory as a rotational speed difference A, and in step S23, it is determined whether or not | A | ≧ K using a predetermined reference rotational speed difference K. If affirmative, the process proceeds to step S24, where it is determined whether or not the rotational speed difference A> 0.
If 0, the control rotation speed Nθ is larger than the rotation speed command value Nin, that is, since the control rotation speed is higher than the target rotation speed, a signal for commanding the motor reverse rotation in step S25 to reduce the engine rotation speed is sent to the pulse motor 63. Output. As a result, the pulse motor 63 rotates in the reverse direction, and the rotational speed of the engine 41 decreases.

On the other hand, if A ≦ 0, the control rotation speed Nθ is smaller than the rotation speed command value Nin, that is, the control rotation speed is lower than the target rotation speed. Outputs the command signal. Thereby, the pulse motor 63 rotates forward, and the rotation speed of the engine 41 increases. If step S23 is denied, the process proceeds to step S27 to output a motor stop signal, whereby the rotation speed of the engine 41 is maintained at a constant value. After executing steps S25 to S27, the process returns to the beginning.

FIG. 10 is a flowchart showing the automatic idle switching circuit 610 as software. In step S21, it is determined whether the vehicle is running, working, or working accelerator. If it is a work, in step S22, it is determined whether or not an auto idle condition at the time of work is satisfied. The conditions are as follows. (1) The auto idle switch 68 is turned on. (2) All operation levers are neutral for a predetermined time (for example, 4 seconds or more). (3) The rotation speed target value Ny is constant (the rotation speed does not fluctuate).

If it is determined in step S21 that the vehicle is running or a work accelerator, the process proceeds to step S23. Step S2
At 3, it is determined whether or not the conditions of the auto-idle at the time of the work accelerator and at the time of running are satisfied. The conditions are as follows. (1) The auto idle switch 68 is turned on. (2) All operation levers are neutral for a predetermined time (for example, 4 seconds or more). (3) The rotation speed target value is constant (the rotation speed does not fluctuate). (4) The accelerator pedal 51 is not operated (is not operated).

If it is determined in step S22 that the auto-idle condition at the time of work is satisfied, or if it is determined at step S23 that the auto-idle condition at the time of running and at the time of work accelerator is satisfied, step S22 is performed. S2
In step 4, the automatic idle changeover switch 607 is switched to the automatic idle side A. On the other hand, if it is determined in step S22 that the auto-idle condition at the time of work is not satisfied, or if it is determined at step S23 that the auto-idle condition at the time of traveling and at the time of work accelerator is not satisfied, step S25 is performed. , The automatic idle changeover switch 607 is switched to the set rotation speed side B.

The operation of the prime mover rotation speed control device configured as described above will be described more specifically. In FIG. 7, during traveling, the selection switch 605 selects the target rotation speed Nt set by the target rotation speed characteristic L1 by the work / travel identification circuit 604. Since the fuel lever 65a is fixed at the minimum operation position during traveling, the maximum value selection circuit 6
The target set speed Ny output from 06 is the target speed Nt according to the characteristic L1. If the above-described auto-idle condition is satisfied, the auto-idle switching circuit 610
The switch 607 is switched to the contact A side in response to the signal from the controller 607, and the automatic idle target rotation speed Nai output from the automatic idle rotation speed generation circuit 611 is output to the servo control circuit 609 as a rotation speed command value Nin. If the above-mentioned auto idle condition is not satisfied, the changeover switch 607 has been switched to the contact B side, so that the target set rotation speed Ny output from the maximum value selection circuit 606 is output to the servo control circuit 609 by the rotation speed command. Output as value Nin.

Next, a description will be given of the case where the fuel lever 65a is set to the minimum operation position during operation and the engine speed is adjusted by the accelerator pedal 51, in other words, the time of operation of the accelerator. At the time of the work accelerator, the selection switch 605 is set by the work / travel identification circuit 604 so that the target rotation speed characteristic L2
The target rotation speed Nda set by the above is selected. Fuel lever 6
Since 5a is fixed to the minimum operation position, the target set speed Ny output from the maximum value selection circuit 606 is the target speed Nda according to the characteristic L2. If the auto-idle condition is satisfied, the auto-idle changeover switch 60
7 is switched to the contact A side, the auto idle target rotation speed Nai is set to the servo control circuit 608 in the same manner as during traveling.
If the auto idle condition is not satisfied, the target set speed Ny selected by the maximum value selection circuit 606 is output to the servo control circuit 609 as the speed command value Nin. In this case, when the depression of the accelerator pedal 51 is detected, the reduction of the engine speed due to the auto-idling is prohibited. Therefore, if the accelerator pedal 51 is depressed at the time of the work accelerator, all of the operation levers for work will be released. Even if the operation is not performed for a predetermined time, for example, 4 seconds, the engine speed does not decrease to the idle speed Nai, and the sense of discomfort disappears.

The case where the engine speed is adjusted by the fuel lever 65a during operation will be described. During work, the selection switch 605 selects the target speed Ndl set by the target speed characteristic L2 by the work / travel identification circuit 604. The function generator 603 outputs a target rotation speed Ndl according to the operation amount of the fuel lever 65a. The target rotation speed Nda output from the selection switch 605 is the idle rotation speed Ndid unless the accelerator pedal 51 is operated, and the target setting rotation speed Ny output from the maximum value selection circuit 606 is the target rotation speed Ndl according to the characteristic L3. is there. If the auto-idle condition is satisfied, the auto-idle target rotation speed Nai is output to the servo control circuit 608 as the rotation speed command value Nin in the same manner as during traveling. If the auto-idle condition is not satisfied, the maximum value is selected. The target set rotation speed Ny selected by the circuit 606 is transmitted to the servo control circuit 608 by the rotation speed command value Nin.
Is output as

As described above, according to this embodiment, the work is performed during the normal work in which the engine speed is adjusted by the fuel lever 65a, and when the vehicle is running and the engine speed is adjusted by the accelerator pedal. The auto-idle condition is switched in accordance with the work accelerator, and the auto-idle function is prohibited when the depression of the accelerator pedal 51 is detected, so that if the accelerator pedal 51 is depressed during the work accelerator, the work Even if all of the operation levers are not operated for a predetermined period of time, the engine speed is not reduced to the idle speed, and the sense of discomfort is eliminated. Further, the engine speed is adjusted in accordance with a signal from a pressure sensor 69 that detects the amount of depression of the accelerator pedal, and the operation / non-operation of the accelerator pedal 51 is determined based on the pressure corresponding to the amount of depression of the accelerator pedal. Therefore, there is no need to provide a dedicated detecting means, and the cost can be reduced.

In the above embodiment, an example in which the target engine speed is set in accordance with the operation amount of the accelerator pedal or the fuel lever has been described. Can be applied. Further, the present invention can be similarly applied to a hydraulic traveling vehicle other than the wheel type hydraulic excavator.

In the above embodiment, the operation lever B
L or the like detects the operating lever means BL, the pulse motor 63 or the like detects the rotation speed adjusting means, the auto idle switching circuit 610 or the auto idle switching switch 607 detects the rotation speed reducing means or the inhibiting means 610, and the traveling pilot pressure sensor 69 detects the pedal. Means 69 and pressure switch 17 constitute lever detecting means 17, respectively.

[0042]

As described above, according to the present invention, the following effects can be obtained. (1) According to the first to third aspects of the present invention, when depression of the accelerator pedal is detected, reduction of the rotation speed of the prime mover by auto-idling is prohibited, so that the accelerator pedal can be depressed at the time of working accelerator. For example, even if all the operation levers are not operated for a predetermined time, the rotation speed of the prime mover is not reduced to the predetermined rotation speed, and the user does not feel uncomfortable. In particular, in the case where the rotation speed of the prime mover is adjusted according to the accelerator pedal depression amount as in the invention of claim 2, the operation / non-operation of the accelerator pedal is determined based on the detected accelerator pedal depression amount. There is no need to provide a dedicated detecting means, and the cost can be reduced. (2)
According to the fourth and fifth aspects of the present invention, the auto-idle condition is switched in accordance with the work, the travel, and the work accelerator. Therefore, it is possible to individually set appropriate conditions during the work, the travel, and the work accelerator. A highly versatile auto idle function can be provided.

[Brief description of the drawings]

FIG. 1 is an overall hydraulic circuit diagram of a wheel hydraulic excavator according to an embodiment.

FIG. 2 is a circuit diagram showing details of a traveling hydraulic circuit of FIG. 1;

FIG. 3 is a diagram showing a boom pilot circuit in a working pilot hydraulic circuit;

FIG. 4 is a diagram showing a circuit for detecting operation / non-operation of an operation lever by auto-idling.

FIG. 5 is a diagram illustrating a control circuit for controlling the engine speed.

FIG. 6 is a diagram for explaining logic for identifying normal work, traveling, and a work accelerator.

FIG. 7 is a diagram illustrating details of a control circuit shown in FIG. 5;

FIG. 8 is a graph illustrating a rotation speed characteristic set by an accelerator pedal and a fuel lever.

FIG. 9 is a flowchart showing a control procedure of an engine speed.

FIG. 10 is a flowchart illustrating details of an auto idle switching circuit;

[Explanation of symbols]

10, 20: variable displacement hydraulic pump 10A: pilot pump 11 to 14, 21 to 25: control valve 17: auto idle pressure switch 31: traveling hydraulic motor 41: engine 51: accelerator pedal 60: controller 63: pulse motor 65 : Potentiometer 65a: Fuel lever 67: Brake switch 68: Auto idle switch 601 to 603: Function generator 604: Work / running discrimination circuit 607: Changeover switch 610: Auto idle switching circuit 611: Auto idle speed generating circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2D003 AA01 AB06 AC06 BA01 CA02 DA04 DB05 3G093 AA10 AA15 BA14 CA04 EB05 EC04

Claims (5)

[Claims] 1. A variable displacement hydraulic pump driven by a prime mover, a traveling hydraulic motor driven by pressure oil discharged from the variable displacement hydraulic pump, and a drive hydraulic motor driven by pressure oil discharged from the variable displacement hydraulic pump A plurality of working hydraulic actuators, an accelerator pedal that adjusts the rotational speed of the traveling hydraulic motor, a rotational speed adjusting unit that adjusts the rotational speed of the prime mover according to at least a depression amount of the accelerator pedal, Operating lever means for operating a plurality of working hydraulic actuators respectively; and a motor rotation speed reducing means for reducing the rotation speed of the motor to a predetermined low rotation speed when all of the operation lever means have not been operated for a predetermined time or more. The operation of the accelerator pedal is detected even when all of the operation levers are not operated for a predetermined time or more. Prohibiting means for prohibiting the operation of the prime mover rotation speed reducing means when performed. 2. A variable displacement hydraulic pump driven by a prime mover, a traveling hydraulic motor driven by pressure oil discharged from the variable displacement hydraulic pump, and driven by pressure oil discharged from the variable displacement hydraulic pump. A plurality of working hydraulic actuators, an accelerator pedal for adjusting a rotation speed of the traveling hydraulic motor, a pedal detecting unit for detecting an operation amount of the accelerator pedal, and a pedal operation amount detected by the pedal detecting unit. Rotation speed adjusting means for adjusting the rotation speed of the prime mover based on: operating lever means for operating each of the plurality of working hydraulic actuators; lever detecting means for detecting operation of the operating lever means; When the detection means detects that all of the operation lever means have not been operated for a predetermined time or more, the rotation of the prime mover is performed. A motor speed reduction means for reducing the number to a predetermined low speed; anda prohibition means for prohibiting the operation of the motor speed reduction means when the operation of the accelerator pedal is detected by the pedal detection means. Features a hydraulic traveling vehicle. 3. The hydraulic traveling vehicle according to claim 2, wherein the operation lever detecting means operates the operation lever means based on whether a control valve for controlling a flow rate and a direction of pressure oil to the working hydraulic actuator is operated. A hydraulic traveling vehicle characterized by detecting the following. 4. A variable displacement hydraulic pump driven by a prime mover, a traveling hydraulic motor driven by pressure oil discharged from the variable displacement hydraulic pump, and driven by pressure oil discharged from the variable displacement hydraulic pump. A plurality of working hydraulic actuators, an accelerator pedal for adjusting the rotation speed of the traveling hydraulic motor, and a rotation for adjusting the rotation speed of the prime mover according to the operation amount of one of a fuel lever and the accelerator pedal. Number adjusting means, operating lever means for operating each of the plurality of working hydraulic actuators, and a motor rotation speed reducing means for reducing the rotation speed of the motor to a predetermined low rotation speed when a predetermined auto idle condition is satisfied; A first operation performed by adjusting the rotation speed by the fuel lever, and a second operation performed by adjusting the rotation speed by the accelerator pedal And a switching means for switching the auto-idle condition in accordance with driving. 5. The hydraulic traveling vehicle according to claim 4, wherein the auto-idle condition of the first operation includes that all of the operation lever means have not been operated for a predetermined time or more, and The hydraulic traveling vehicle according to claim 1, wherein the auto-idle condition for traveling includes that all of the operation lever means are not operated and the accelerator pedal is not operated.