JPH06306892A - Running control device for construction machinery - Google Patents

Abstract

PURPOSE:To improve the extent of rectilinearity by making a part of pressure oil at either side, where discharge rate of a first or second pump, flow into a pipeline at the other side, and setting the flow and pressure of symmetrical travel motor feeding pressure oil. CONSTITUTION:When setting and operating signals of an operating mode switch 82, a travel speed setting operation part 83 and two symmetrical travel levers 27L and 27R are all inputted into a controller 73, a transfer command signal is outputted to a solenoid 78, and a solenoid selector valve 77 is selected to a pilot pressure interconnecting oil passage from a tank interconnecting oil passage. Next, pilot pressure acts on a pilot port 84, and a throttle part interconnecting value 63 is selected to an oil passage with a throttle part, and each pressure oil of a first pump 20 and a second pump 21 is fed to two symmetrical travel motors 2L and 2R. In this case, if there is a difference in discharge rate between both these pumps 20 and 21, differential pressure is produced between two pipelines 37 and 62 as well, and thereby a part at a side being higher in oil pressure flows into a pipeline at a side being lower via a throttle part 85. With this constitution, travel motor feeding pressure oil flow rate and the pressure oil can be made into symmetrical sameness, and rectilinearity is thus improvable too.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crawler type construction machine such as a hydraulic excavator and a traveling control device for a work vehicle.

[0002]

2. Description of the Related Art FIG. 3 is a side view of a hydraulic excavator.
In the figure, 1 is a lower traveling body, 2L and 2R are left and right traveling motors, 3 is an upper revolving body, 4 is a revolving motor, 5 is a work attachment mounted on the front part of the upper revolving body 3, and 6
Is a boom of the work attachment 5, 7 is an arm, 8 is a bucket, 9 is a boom cylinder, 10 is an arm cylinder,
Reference numeral 11 is a bucket cylinder. FIG. 4 is a traveling circuit diagram of a conventional hydraulic excavator. In the figure, 12L,
Reference numeral 12R is a traveling pilot switching valve for controlling the traveling motors 2L and 2R, 13 is a traveling pilot switching valve for controlling the traveling motor 4, 14 is an arm pilot switching valve for controlling the arm cylinder 10, and 15 is a boom cylinder 9 A boom pilot switching valve for control, 16 is a bucket pilot switching valve for controlling the bucket cylinder 11, 17 is a straight traveling valve, and 18L and 18R are pilot opening / closing valves provided at the outlets of the center bypass oil passages 19L and 19R, respectively.
Reference numerals 20 and 21 are first and second pumps, 22 is a pilot pump, 23 is an oil tank, 24L and 24R are left and right traveling remote control valves, and 25F and 26F are traveling remote control valves 24L and 24L.
24R forward pilot valve, 25R, 26R
Are reverse pilot valves, 27L and 27R are left and right traveling levers, 28L and 28R are left and right working machine remote control valves, and 29L and 29R are working machine remote control valves 28L and 2L.
8R operation levers for working machines, reference numerals EE,
~, O indicates the connection of the pilot line.

Next, a conventional running circuit will be described with reference to FIG. Two group A pilot switching valves that control various hydraulic actuators equipped on hydraulic excavators
(12L, 14, 13) and B (12R, 15, 16)
And the left and right traveling pilot switching valves (hereinafter referred to as traveling switching valves) 12L and 12R are arranged in the front rows of groups A and B, respectively. ing. Here, the driver does not operate the work machine operation levers 29L and 29R,
Both the traveling levers 27L and 27R are operated forward, for example. Since the pilot secondary pressures derived from the pilot valves 25F and 26F act on the pilot ports 30 and 31 of the travel switching valves 12L and 12R, respectively,
The travel switching valves 12L and 12R are switched to the power position and the power position, respectively. The pressure oil from the first pump 20 is supplied to the left travel motor 2L via the pipe 32, the oil passages 33 and 34, the position of the travel switching valve 12L, and the pipe 35. At the same time, the pressure oil from the second pump 21 passes through the conduit 36, the oil passage 37, the independent oil passage position Y of the straight travel valve 17, the oil passages 38 and 39, the position of the travel switching valve 12R, and the pipe 40. , To the right travel motor 2R. Therefore, the hydraulic excavator goes straight ahead.

Next, a case will be described in which the operating lever for the working machine is moved to operate another hydraulic actuator, for example, the arm cylinder 10 while the hydraulic excavator is moving straight ahead. When the arm pulling operation is performed by the working machine operation lever 29L while the vehicle is moving straight ahead, the arm pilot switching valve 14 (hereinafter referred to as the arm switching valve 14) is switched to the open position. The pilot primary pressure from the pilot pump 22 is the pipelines 41, 42, 43, the throttle portion 44, the pipeline 45, the opening oil passage position of the sub valve 46 of the travel switching valve 12L, the oil passage 47, the pipelines 48, 49, and the shuttle. It acts on the pilot port 52 via the valve 50 and the oil passage 51. Therefore, the traveling straight-ahead valve 17 is switched to the traveling straight-ahead position. Thereby the second
The pressure oil from the pump 21 is supplied to the pipe line 36, the oil line 37, the position of the straight travel valve 17, the oil lines 53 and 54, the check valve 55,
The bottom side oil chamber of the arm cylinder 10 is supplied through the oil passages 56, 57 and 58, the check valve 59, the oil passage 60, the arm position of the arm switching valve 14, and the pipe passage 61. At the same time, the pressure oil from the first pump 20 flows through the pipe line 32 and one of the oil lines 3
3, 34, the drive position of the travel switching valve 12L, and the pipe 35, and is supplied to the left travel motor 2L, and the other is branched at the pipe 32 to the oil passage 62, the linear position of the traveling linear valve 17, and the oil passage. Three
It is supplied to the right traveling motor 2R through the passages 8 and 39, the position of the traveling switching valve 12R, and the pipe 40. That is, since the pressure oil from the first pump 20 is supplied in parallel to the left and right traveling motors 2L and 2R, the traveling speed decreases but the vehicle can travel straight ahead.

[0005]

When a hydraulic excavator equipped with two variable displacement hydraulic pumps travels straight without operating a hydraulic actuator for a working machine, pressure oil from the first pump is fed to the left travel motor. In addition, the pressure oil from the second pump is separately supplied to the right traveling motor. However, with the first pump and the second pump,
The pump displacement (cc / rev) has an allowable error. Therefore, when the first and second pumps are rotating, there is a slight difference in their discharge flow rates.
In particular, full lever operation of the travel lever (means lever operation when the travel lever is operated deeper than the neutral position to the pivot end)
During this, the difference in the discharge flow rate was large when the pump tilt was held at the intermediate angular position in the tilt angle range. Therefore, when the hydraulic excavator travels straight ahead, it may be deflected, which is unsatisfactory in terms of work and safety. An object of the present invention is to provide a traveling control device for a construction machine capable of solving the above problems.

[0006]

According to the traveling control device of the present invention, the left and right traveling motors mounted on the construction machine are driven by independent first and second variable displacement pumps, respectively. , The pressure oil flow rate from the second pump is supplied to the traveling motor in accordance with the operation change position of the traveling lever, and the operation state detecting means for the left and right traveling levers and the neutral position detecting means for the working machine operating lever are provided. In addition, a traveling speed setting operation unit is provided, and the maximum pump discharge flow rate corresponding to each set speed is set by adjusting the traveling speed setting operation unit, and the pump along with the engine speed is selected by the operation mode switch operation. In the traveling control device that regulates tilting, a communication valve with a throttle portion is provided between circuits that lead from the first and second pumps to the left and right traveling switching valves, respectively. The pilot port of the communication valve with the throttle section and the pilot pressure hydraulic pressure source are connected via an electromagnetic switching valve, and a command signal is output from the controller to the solenoid of the electromagnetic switching valve to set the work mode switch and traveling speed. When the operating section is adjusted and the left and right travel levers are both fully operated, the adjustment operation signal and the full lever operation signal are input to the controller.
The controller judges based on the input signal,
By outputting a switching command signal from the controller to the electromagnetic switching valve, the electromagnetic switching valve is switched to the pilot pressure communication oil passage position. Further, when the traveling lever and the working machine operation lever are simultaneously operated, the pressure oil from one hydraulic pump of the first and second pumps is supplied to the left and right traveling motors and the pressure oil from the other hydraulic pump is operated. The traveling straight-ahead valve that performs the switching operation so as to supply to the working hydraulic actuator and the communication valve with the throttle portion are integrally formed.

[0007]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a circuit diagram showing a traveling control device of the present invention. In the figure, the same reference numerals are given to those using the same constituent elements as those in the prior art. Reference numeral 63 is a communication valve with a throttle portion formed integrally with a traveling straight-ahead valve (corresponding to the traveling straight-ahead valve 17 in FIG. 4), 64, ..., 72 are shuttle valves for selecting a high pilot secondary pressure respectively, and 73 is a Controllers, 74, 75, 76 are pressure sensors,
Reference numeral 77 is an electromagnetic switching valve that is an electro-oil converter, 78 is a solenoid of the electromagnetic switching valve 77, and 79 and 80 are the first pump 20 and the second pump.
Each regulator of the pump 21, 81 is an engine,
Reference numeral 82 is a work mode switch (specifically, a work mode switch), and 83 is a traveling speed setting operation unit. By switching the work mode switch 82, the rotation of the engine (81) is changed to H (high-speed rotation for heavy load) and S.
It is possible to switch to a desired work mode of (medium speed rotation for normal load) and FC (low speed rotation for fine operation work). When the FC mode (so-called fine control mode) is selected, the pump tilt is maintained at an intermediate angular position in the tilt angle range, and the maximum flow rate of the first and second pumps (22, 23) is reached. The flow rate is reduced to a predetermined cut flow rate (Qcut) of (Qmax). In addition, the traveling speed setting operation unit 83 can adjust and set a required traveling speed in advance steplessly or stepwise.

Next, the construction of the traveling control device of the present invention is shown in FIG.
I will describe. The left and right traveling motors 2L and 2R mounted on the construction machine are driven by independent first and second variable displacement pumps 20 and 21, respectively.
The pressure oil flow rate from the second pump (20, 21) is supplied to the traveling motor (2L.2R) according to the operation displacement amount of the traveling levers (27L, 27R), and the left and right traveling levers 27L, 27R are supplied. Pressure sensors 75 and 76 are provided as operation state detection means, respectively, and a work machine operation lever 29 is provided.
The pressure sensor 74 serves as a neutral position detecting means for L and 29R.
Is provided. Further, the traveling speed setting operation unit 83 is provided for the controller 73, and the maximum pump discharge flow rate corresponding to each set speed is set by adjusting the traveling speed setting operation unit 83, and the work mode switch 82 is selected. By the operation, the pump tilt regulation is performed together with the engine (81) rotation speed. And the first and second
A communication valve with a throttle part 6 between the circuits communicating from the pumps (20, 21) to the left and right travel switching valves (12L, 12R), respectively.
3, a pilot port 84 of the communication valve 63 with a throttle portion, and a pilot pump (pilot pressure hydraulic source) 22.
And the solenoid 78 of the electromagnetic switching valve 77 and the controller 73 are communicated with each other. Then, the work mode switch 82 and the traveling speed setting operation section 83 are adjusted and the left and right traveling levers (2
7L, 27R) only when full lever operation
The adjustment operation signal and the full lever operation signal are input to the controller 73, the controller 73 makes a determination based on the input signal, and the controller 73 outputs a switching command signal to the electromagnetic switching valve 77, whereby the electromagnetic switching valve 77 is configured to be switched to the pilot pressure communication oil passage position S. Further, the communication valve 63 with the throttle portion is formed integrally with the straight traveling valve (corresponding to the straight traveling valve 17 in FIG. 4). The throttle portion 85 provided at the oil passage position with the throttle portion of the communication valve 63 with the throttle portion is not limited to the fixed throttle portion, and a variable throttle portion can be provided.

Next, the operation of the traveling control device of the present invention will be described. In the traveling control device of the present invention, when at least one of the working machine operating levers 29L and 29R is operated, or when both the left and right traveling levers 27L and 27R are not operated, or the left and right traveling levers. When only one of 27L and 27R is operated and the detection signals from the pressure sensors 74, 75 and 76 are input to the controller 73, the controller 7
In No. 3, it is determined that the above cases have occurred, and the controller 73 does not output the switching command signal to the electromagnetic switching valve 77. Therefore, since the electromagnetic switching valve 77 is at the tank communication oil passage position, the pilot pressure from the pilot pump 22 does not act on the pilot port 84 of the communication valve 63 with a throttle portion. That is, in the above-mentioned case, the communication valve 63 with a throttle portion only fulfills the function of the traveling straight-ahead valve (17) of the prior art.

Next, the working machine operating levers 29L and 29R
The operation mode switch 82 and the traveling speed setting operation section 83 are adjusted and the left and right traveling levers (27L, 27R) are operated together without operating the. Adjustment operation signals from the work mode switch 82 and the traveling speed setting operation unit 83 are input to the controller 73, and operation state detection signals of the left and right traveling levers (27L, 27R) are detected by the shuttle valves (71, 72) and the pressure sensor. It is input to the controller 73 via (75, 76). Controller 7
In 3, the arithmetic processing is performed based on the detection signal, it is determined that the predetermined output condition is satisfied, and the switching command signal is output to the solenoid 78 of the electromagnetic switching valve 77. Solenoid 78
The solenoid switching valve 77 is switched from the tank communication oil passage position N to the pilot pressure communication oil passage position S0. The pilot pressure from the pilot pump 22 is supplied to the pipes 87, 8
8, 89, the solenoid position of the electromagnetic switching valve 77, and the pipeline 90,
It acts on the pilot port 84. Communication valve with throttle 63
Changes from the Y'position to the oil passage position with throttle. First
The pressure oil from the pump 20 and the second pump 21 is supplied to the left and right traveling motors 2 via the traveling switching valves 12L and 12R, respectively.
It is supplied to L and 2R. In this case, for example, when the discharge flow rate of the first pump 20 is slightly higher than that of the second pump 21, a slight differential pressure is generated between the pipe lines 62 and 37. Therefore, a part of the pressure oil from the first pump 20 flows into the pipeline 37 through the throttle portion 85 in the oil passage position with throttle portion 85.
Therefore, the flow rate of the pressure oil supplied to the traveling motors 2L and 2R and the working pressure are the same on the left and right, so that the construction machine can go straight without causing traveling deflection. In addition, in FIG.
It is a flow chart which shows the function of controller 73 in the present invention.

[0011]

When the hydraulic excavator equipped with the variable displacement type first and second pumps travels straight without operating the hydraulic actuator for the working machine, the pressure oil from the first and second pumps travels left and right. The motors are supplied separately. However, both pumps have an allowable error in the amount of tilting of the pump, and in particular, when the tilting of the pump is held in the middle position of the tilting range when the travel lever is fully operated, The difference in the discharge flow rate of was large. Therefore, the vehicle may be deflected when traveling straight ahead, which is unsatisfactory in terms of work and safety. However, in the travel control device of the present invention, a communication valve with a throttle portion is provided between the circuits communicating from the first and second pumps to the left and right travel switching valves, respectively, and the pilot port of the communication valve with the throttle portion and the pilot pressure hydraulic pressure are provided. Power source through the solenoid directional control valve, the solenoid of the solenoid directional control valve and the controller are communicated, the work mode switch and the traveling speed setting operation section are adjusted, and only the left and right traveling levers are full levers. When operated, the controller outputs a switching command signal to the electromagnetic switching valve.
As a result, the communication valve with the throttle portion is switched to the oil passage position with the throttle portion, so that a part of the pressure oil on the hydraulic pump side of the first and second pumps, which has a large discharge flow rate, is attached to the throttle valve of the communication valve with the throttle portion. It flows through the oil passage position into the pipe on the side with the smaller discharge flow rate. As a result, the flow rate of pressure oil supplied to the traveling motor and the operating pressure become the same on the left and right, so that the construction machine can go straight without causing traveling deflection. Further, since the communication valve with the throttle portion is formed integrally with the straight traveling valve, the valve can be manufactured compactly and at low cost. Therefore, in the construction machine provided with the traveling control device of the present invention, traveling deflection can be prevented when traveling straight ahead without operating the working machine hydraulic actuator, and traveling performance and safety can be improved.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a travel control device of the present invention.

FIG. 2 is a flowchart showing the function of the controller in the present invention.

FIG. 3 is a side view of the hydraulic excavator.

FIG. 4 is a conventional traveling circuit diagram of a hydraulic excavator.

[Explanation of symbols]

 2L, 2R Traveling motor 12L, 12R Traveling pilot switching valve 17 Traveling straight valve 20,21 1st, 2nd pump 22 Pilot pump 27L, 27R Traveling lever 29L, 29R Operation lever for working machine 63 Communication valve with throttle 73 Controller 74, 75, 76 Pressure sensor 77 Electromagnetic switching valve 82 Working mode switch 83 Travel speed setting operation unit

Claims (2)

[Claims] 1. A left and right traveling motors mounted on a construction machine are driven by independent first and second variable displacement pumps, respectively, and pressure oil flow rates from the first and second pumps are controlled by a traveling lever. Is supplied to the traveling motor in accordance with the operation displacement amount, and the operating state detecting means for the left and right traveling levers and the neutral position detecting means for the working machine operating lever are provided, and the traveling speed setting operation portion is provided. A travel control device in which the maximum pump discharge flow rate corresponding to each set speed is set by adjusting the travel speed setting operation unit, and the engine rotation speed and the pump tilting restriction are controlled by the operation mode switch selection operation. In the first
And a communication valve with a throttling part is provided between the circuits leading from the second pump to the left and right travel switching valves, respectively, and the pilot port of the throttling communication valve and the pilot pressure hydraulic source are communicated via the solenoid switching valve. When the solenoid of the electromagnetic switching valve and the controller are communicated with each other, the work mode switch and the traveling speed setting operation section are adjusted, and both the left and right traveling levers are both fully operated, the adjustment operation signal and the full lever operation are performed. A signal is input to the controller, the controller makes a judgment based on the input signal, and the controller outputs a switching command signal to the solenoid switching valve, so that the solenoid switching valve is switched to the pilot pressure communication oil passage position. A traveling control device for a construction machine characterized by the above. 2. The traveling control device for a construction machine according to claim 1, wherein when the traveling lever and the working machine operation lever are simultaneously operated, the pressure from one of the first and second hydraulic pumps is applied. A traveling straight valve that performs switching operation so that oil is supplied to the left and right traveling motors and pressure oil from the other hydraulic pump is supplied to the operated hydraulic actuator, and a communication valve with a throttle is integrally formed A traveling control device for a construction machine characterized by the above.