JPH0678047U - Running hydraulic circuit of tracked vehicle - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the traveling operability by improving the traveling hydraulic circuit of a tracked vehicle. [Configuration] Flow control valves 4-1, 4-2 and flow control valves 5-1, 5 in the oil return line of the traveling motor 1 that drives the endless track.
-2 is provided. The oil passages 7-1 and 7-2 and the oil passages 8-1 and 8-2 connected via the check valves 6-1 and 6-2 connect the switching valve 9 to the traveling motor 1. Flow control valves 4-1 and 4-2 are switching valves 9
Of the oil return line from the traveling motor 1 is adjusted by an external signal commanded from the controller 17 via the pressure reducing valves 13-1 and 13-2 according to the operation angle of the operation valve 11 for controlling the direction and the opening degree. To do. The opening of the flow control valves 5-1 and 5-2 is determined by the balance between the spring force and the differential pressure across the flow control valves 4-1 and 4-2. The rotation speed of the pump driving prime mover 41 is input from the rotation sensor 49 to the controller 17, and the controller 17 acts to open the flow control valves 5-1 and 5-2 even if the operation angle of the operation valve 11 is the maximum value. Is limited to an opening degree according to the amount of oil discharged from the hydraulic pump 42.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a traveling hydraulic circuit of a track-type vehicle in which an undercarriage (crawler track) is attached to a lower traveling body.

[0002]

[Prior art]

 A traveling hydraulic circuit of a conventional tracked vehicle will be described with reference to FIG. Since the left and right running circuits are symmetrical, only the left system will be described with reference numerals, but the right system is exactly the same.

In FIG. 4, reference numeral 1 denotes a traveling motor that drives an endless track of a tracked vehicle, and a switching valve 9 that determines the rotation direction of the traveling motor 1 is connected to a pilot oil passage 10-1 or 10-2. The pressure oil discharged from the pump 42 driven by the prime mover (engine) 41 to the oil passage 16 is switched by the operation command of the operation valve 11 acting on the end portion of the switching valve 9 via the oil passage 7-1. Alternatively, it is led to 7-2 and supplied to the traveling motor 1 via the oil passage 8-1 or 8-2.

The prime mover 41 drives a right system pump 43 and a pilot pump 44 together with the left system pump 42. The pilot pump 44 supplies pilot pressure to the operation valve 11. The operation valve 11 is a remote control valve operated by an operator.

A counter balance valve 51 is provided in the oil return line from the oil passages 8-1, 8-2 to the oil passages 7-1, 7-2. The counter balance valve 51 closes the oil passages 7-1 and 7-2 from the switching valve 9 and closes the oil passages 8-1 and 8-2 from the traveling motor 1 at the neutral position. The oil passages 52-1 and 52-2 counter the pressure from the oil passages 7-1 and 7-2 on the switching valve 9 side of the check valves 53-1 and 53-2 through the orifices 54-1 and 54-2. It leads to the end of the balance valve 51.

The check valves 53-1 and 53-2 are provided between the oil passage 7-1 and the oil passage 8-1, and between the oil passage 7-2 and the oil passage 8-2, respectively. The direction from 9 to the traveling motor 1 is free flow, and the flow in the opposite direction is closed to secure the return oil flow to the counter balance valve 51.

In the traveling hydraulic circuit configured as described above, when the operation valve 11 is operated to send a pressure signal to the switching valve 9 via the pilot oil passage 10-1 and the switching valve 9 is switched to the left position, the pump is turned on. The flow rate of oil discharged from 42 reaches the traveling motor 1 via the oil passage 16, the oil passage 7-1, the check valve 53-1 and the oil passage 8-1.

At this time, the pressure in the oil passage 7-1 rises, the pressure acts on the left end of the counter balance valve 51 via the orifice 54-1 and the oil passage 52-1, and the counter balance valve 51 switches to the left position. Therefore, the oil that drives the traveling motor 1 reaches the tank 47 through the oil passage 8-2, the counterbalance valve 51, the oil passage 7-2, the switching valve 9, and the oil passage 48. In addition, the relief valves 3-1 and 3-2 provided between the oil passages 8-1 and 8-2 are set to a set pressure when the traveling motor 1 is driven or stopped. It prevents the above high pressure.

Similarly, when the operation valve 11 is operated in reverse, the switching valve 9 and the counter balance valve 51 are switched to the right position, and the traveling motor 1 rotates in the opposite direction.

The hydraulic circuit of the right system is similarly configured.

[0011]

[Problems to be solved by the device]

 In the travel hydraulic circuit configured as described above, the travel speed is adjusted by adjusting the flow rate from the pump 42 to the travel motor 1 by adjusting the operation angle of the operation valve 11 and thus the opening of the switching valve 9. It controls the rotation speed. On the other hand, the switching direction and opening of the counter balance valve 51 are controlled by the pressure on the inflow side of the oil passages 7-1 and 7-2, and are not directly operated by the operation valve 11.

Therefore, when the traveling speed increases due to the weight of the aircraft when going down a slope, or when the operating angle of the operation valve 11 is returned during deceleration, the required amount of oil for the traveling motor 1 is reduced due to the inertia of the aircraft. Is greater than the inflow oil amount, the pressure in the oil passage 8-1 on the inflow side drops, the counterbalance valve 51 closes, the pressure in the oil passage 8-2 on the outflow side rises, and Phenomena such as hunting and sudden braking occur, and this is one of the factors that deteriorate the driving operability.

It is known that this is because the operation angle of the operation valve 11 does not correspond to the movement of the counterbalance valve 51.

The present invention has been made in view of the above circumstances, and an object thereof is to improve deterioration of traveling operability due to a conventional counterbalance valve.

[0015]

[Means for Solving the Problems]

 In order to solve the above problems, the invention described in claim 1 supplies hydraulic oil to a traveling motor from a pump driven by a prime mover through a switching valve that switches a motor rotation direction by an operator's operation. In the traveling hydraulic circuit of the track-type vehicle to be supplied, (1) between the switching valve and the traveling motor, the flow from the traveling motor in the direction of the switching valve is closed at the neutral position, and the valve opening is adjusted by an external signal. The flow rate control valve on the motor side for adjusting the passing flow rate, and (2) the switching valve side (downstream side) of the flow rate control valve on the motor side, and the pressure on the motor side (upstream side) of the flow rate control valve on the motor side. Is received at one end of the spool, and the other end receives the pressure and spring force on the switching valve side of the motor side flow control valve, and the force due to the differential pressure between the motor side and the switching valve side of the motor side flow control valve is the spring force. Than the power of In the negative case (neutral position), the flow from the traveling motor in the direction of the switching valve is allowed, and when the force due to the differential pressure is larger than the force due to the spring force, the flow is limited and the force due to the differential pressure is caused by the spring force. A flow rate control valve on the switching valve side that limits the amount of oil passing through so that it is always balanced with the force, and (3) a motor side of the flow rate control valve on the motor side and a flow control valve side of the flow rate control valve on the switching valve side. (4) A check valve installed in the oil passage that connects the control valve to make the flow from the switching valve in the direction of the traveling motor a free flow direction and to close the flow in the opposite direction, and (4) Operation command signals from the operating section operated by the operator. No. and a control system that associates the opening of the motor-side flow control valve with each other, the traveling hydraulic circuit of the tracked vehicle.

According to a second aspect of the invention, in the control system of the first aspect, the maximum opening of the motor-side flow control valve is limited according to the rotation speed of the prime mover, and the maximum value of the operation command signal of the operation unit is set. It is a traveling hydraulic circuit of a tracked vehicle configured to correspond to.

[0017]

[Action]

 According to the invention described in claim 1, when the vehicle speed is accelerated due to the weight of the vehicle body while descending a slope, the rotational speed of the traveling motor tends to increase. In that case, the opening degree of the motor side flow control valve is increased. However, since the amount of oil passing through this motor-side flow control valve tends to increase, the differential pressure before and after this motor-side flow control valve also increases and the spring force of the switching valve-side flow control valve increases. Since it becomes larger and the opening of the flow control valve on the switching valve side becomes smaller, the amount of oil passing through the flow control valve on the motor side can be controlled to a constant flow rate, and the traveling speed can be kept constant according to the command value of the operating section. Be done. The valve opening of the motor-side flow control valve is adjusted by an external signal from the control system that is generated in response to an operation command signal from the operation unit.

According to the second aspect of the invention, when the rotational speed of the prime mover decreases, the amount of pump discharge oil also decreases. In this case, the control system that detects the rotational speed of the prime mover functions to operate the operation command signal of the operating section. Even if is the maximum value, the opening of the motor side flow control valve is limited to the opening according to the pump discharge oil amount, so the traveling speed is kept constant according to the command value of the operating unit even when descending a slope. .

[0019]

【Example】

 The present invention will be described below with reference to a first embodiment shown in FIGS. 1 and 2 and a second embodiment shown in FIG. Since the left and right traveling circuits are symmetrical, only the left system will be described with reference numerals, but the right system will be exactly the same.

First Embodiment First, a first embodiment of the present invention will be described in detail with reference to FIG. 1 and FIG. 2 which is an enlarged view of a main part of FIG.

As shown in FIG. 1, check valves 2-1, 2-2, relief valves 3-1, 3-2, and switching valves are provided in the hydraulic line of the traveling motor 1 that drives the endless track of the tracked vehicle. Valve side flow control valves 4-1 and 4-2, motor side flow control valves 5-1 and 5-2 and check valves 6-1 and 6-2 are provided, and oil passages 7-1 and 7-2 are also provided. The switching valve 9 is connected to the traveling motor 1 via the oil passages 8-1 and 8-2.

The relief valves 3-1 and 3-2 release the high pressures of the oil passages 8-1 and 8-2 to the oil passages 8-2 and 8-1 on the opposite sides. The check valves 2-1 and 2-2 are respectively located between the oil passage 45 and the oil passage 8-1, and between the oil passage 45 and the oil passage 8-2, respectively. Make free flow in the direction of oil passage 8-2 from passage 45 and close the flow in the opposite direction. These check valves 2-1 and 2-2 replenish oil from the oil passage 45 when the oil passages 8-1 and 8-2 have a negative pressure at the time of stoppage, etc. to prevent damage to the motor and to prevent braking. It is provided to stabilize the pressure.

An operation valve 11 as an operation section operated by an operator is connected to a pilot pressure acting portion of the switching valve 9 via pilot oil passages 10-1 and 10-2, and further, a pilot oil passage 10 is provided. -1, 10-2 are provided with pressure sensors 12-1, 12-2, and the pressure detection lines of the pressure sensors 12-1, 12-2 are connected to the input terminal of the controller 17.

A prime mover (engine) 41 drives pumps 42, 43, 44. The pump 42 is a main pump that supplies hydraulic pressure to the switching valve 9 of the left system via the oil passage 16, the pump 43 is a main pump that supplies hydraulic pressure to the switching valve of the right system, and the pump 44 is the operation valve 11 etc. It is a pilot pump that supplies pilot pressure to the tank and the suction port is connected to the tank 47. Reference numeral 48 is an oil passage on the oil discharge side which communicates with the tank 47.

The prime mover 41 is provided with a rotation sensor 49, and the rotation speed detection line of the rotation sensor 49 is connected to the input terminal of the controller 17.

The output terminal of the controller 17 is connected to the solenoids of the electromagnetic proportional pressure reducing valves 13-1 and 13-2, while the pilot pressure line from the pilot pump 44 is connected to the pressure reducing valves 13-1 and 13-2. Through the pilot oil passages 14-1 and 14-2 to the pilot pressure acting portions of the motor side flow control valves 5-1 and 5-2.

From the pressure sensors 12-1 and 12-2 to the controller 17, the pressure reducing valves 13-1 and 13-2, and the pilot oil passages 14-1 and 14-2, the motor side flow control valves 5-1 and 5 are connected. The control system up to -2 makes the operation command signal of the operation valve 11 operated by the operator correspond to the opening degree of the motor side flow control valves 5-1 and 5-2. Correspond the maximum opening of 5-1 and 5-2 and the maximum value of the operation command signal of operation valve 11. Further, the control system from the rotation sensor 49 to the motor side flow control valves 5-1 and 5-2 via the controller 17 and the like is such that the maximum opening of the motor side flow control valves 5-1 and 5-2 is set to the motor 41. It is limited according to the number of rotations.

When the operation valve 11 is operated, the operation command of the operation valve 11 acts on the end of the switching valve 9 via the pilot oil passage 10-1 or 10-2 to switch the switching valve 9. The flow rate from the pump 42 is guided to the oil passage 7-1 or 7-2, and the pressure sensors 12-1 and 12-2 of the pilot oil passages 10-1 and 10-2 cause the command signal ( The pilot pressure) is detected, converted into an electric signal and input to the controller 17. The rotation sensor 49 detects the engine speed and inputs it to the controller 17. The electric signal output from the controller 17 is converted into a pressure signal by the pressure reducing valves 13-1 and 13-2, and the motor side flow control valves 5-1 and 5- are connected via the oil passages 14-1 and 14-2. Operate 2.

As shown in FIG. 2, the motor-side flow control valves 5-1 and 5-2 close the oil passages 8-1 and 8-2 from the traveling motor 1 at the neutral position, while The valve opening is adjusted by an external signal from the electromagnetic proportional pressure reducing valves 13-1, 13-2 to change from the oil passages 8-1, 8-2 to the switching valve side flow control valves 4-1 and 4-2. Control the flow rate of. That is, the motor-side flow control valves 5-1 and 5-2 are flow control valves that also have a function as a escape prevention valve that controls the amount of oil passing from the traveling motor 1 to the switching valve 9.

The switching valve side flow control valves 4-1 and 4-2 receive the pressure on the upstream side of the motor side flow control valves 5-1 and 5-2 at one end of the spool, and the motor side flow control at the other end of the spool. Force due to the differential pressure between the upstream and downstream sides of the motor side flow control valves 5-1 and 5-2, which receives the pressure and spring force on the downstream side of the control valves 5-1 and 5-2 (hereinafter referred to as differential pressure). Is smaller than the force due to the spring force, the opening is increased to increase the amount of oil passing from the traveling motor 1 in the direction of the switching valve 9. However, when the differential pressure is larger than the force due to the spring force, the opening is decreased. Reduce the amount of oil passing through. In other words, the flow rate control valves 4-1 and 4-2 on the switching valve side control the amount of oil that passes through so that the above-mentioned differential pressure is always constant in balance with the force due to the spring force.

The check valves 6-1 and 6-2 are located between the oil passages 7-1 and 8-1 and between the oil passages 7-2 and 8-2, respectively, and are connected from the switching valve 9 to the traveling motor 1. Free flow in the direction of and closed flow in the opposite direction.

Next, the function of the control system will be described. The force due to the spring force of the flow control valves 4-1 and 4-2 on the switching valve side is the mode when the rated oil amount of the traveling hydraulic system is at the maximum opening. Although it is slightly larger than the force due to the differential pressure when passing through the flow rate control valves 5-1 and 5-2 (hereinafter referred to as the rated differential pressure), when the rotational speed of the prime mover 41 becomes lower than the rated rotational speed. Naturally, the maximum discharge oil amount decreases, and in that case, when the maximum discharge oil amount passes through the motor side flow control valves 5-1 and 5-2 by the controller 17 which detects the rotation speed by the rotation sensor 49. The maximum opening of the motor side flow control valves 5-1 and 5-2 is limited so that the differential pressure is equal to the rated differential pressure, and the maximum opening is operated by the operator. Change the gain so that it becomes the maximum value.

The traveling hydraulic circuit of the right system is also configured similarly to the left system.

(Operation of the First Embodiment) Next, the operation of the traveling hydraulic circuit configured as shown in FIGS. 1 and 2 will be described. The operation valve 11 is operated to operate the pilot oil passage 10-1. Pressure signal is sent to the switching valve 9 and the switching valve 9 is switched to the left position, the discharge flow rate from the pump 42 is the oil passage 16, the switching valve 9, the oil passage 7-1, the check valve 6-1, and the oil passage 8 It reaches the traveling motor 1 via -1 and drives the traveling motor 1.

At this time, the controller 17 receives the operation command signal of the operation valve 11 detected by the pressure sensor 12-1, and outputs a command signal corresponding to the operation angle of the operation valve 11 and the rotation speed of the prime mover 41 to the pressure reducing valve. Output to 13-2, supply pilot pressure to motor side flow control valve 5-2 through this pressure reducing valve 13-2, and open motor side flow control valve 5-2.

Therefore, the oil that drives the traveling motor 1 from the oil passage 8-1 is the oil passage 8-2, the motor side flow control valve 5-2, the switching valve side flow control valve 4-2, the oil passage 7 -2, the switching valve 9 and the oil passage 48 to reach the tank 47.

On the other hand, when the operation valve 11 is operated in reverse, the switching valve 9 is switched to the right position, and the discharge flow rate from the pump 42 is the oil passage 16, the oil passage 7-2, the check valve 6-2, the oil passage. The oil after reaching the traveling motor 1 via 8-2, the traveling motor 1 rotates in the opposite direction, and the oil after driving the traveling motor 1 is the oil passage 8-1 and the motor side flow control valve 5-1. , The switching valve side flow control valve 4-1, the oil passage 7-1, the switching valve 9 and the oil passage 48 to reach the tank 47.

Further, the high pressure generated in the oil passages 8-1 and 8-2 when the traveling motor 1 is started and stopped is released to the low-pressure side oil passage by the relief valves 3-1 and 3-2. Prevents damage to pipes, etc. The check valves 2-1 and 2-2 are connected between the check valves 2-1 and 2-2 via the oil passage 45 when the oil passages 8-1 and 8-2 have a negative pressure due to a stop or the like. Replenish the suctioned oil to the negative pressure side of oil passages 8-1 and 8-2 to prevent damage to the motor and stabilize the brake pressure.

In such a drive motor drive, when decelerating and when the operation angle of the operation valve 11 is in the intermediate position between the neutral position and the maximum position, the opening degree of the switching valve 9 is small and the travel motor 1 is operated. Although the amount of oil decreases, the opening of the motor side flow control valves 5-1 and 5-2 is sufficiently secured by the function of the controller 17, and the differential pressure between the upstream side and the downstream side is small, so the flow rate at the switching valve side is small. The openings of the control valves 4-1 and 4-2 remain open, and the rotation speed (travel speed) of the traveling motor 1 is freely adjusted by operating the operation valve 11.

Next, during braking (when the operation valve 11 is returned to the neutral position), the openings of the switching valve 9 and the motor side flow control valves 5-1 and 5-2 are closed, and the oil passage 8- 1 Or brake pressure rises and stops in oil passage 8-2. At this time, the controller 17 works to control the closing speed of the motor-side flow control valves 5-1 and 5-2 without abruptly closing them, thereby enabling a smooth vehicle stop. .

Further, when the vehicle speed is accelerated by the weight of the vehicle body while descending a slope, the rotational speed (traveling speed) of the traveling motor 1 tends to increase, but in that case, the motor side flow control valve 5-1 , 5-2, the amount of oil passing through the flow control valves 5-1 and 5-2 tries to increase even though the opening of the flow control valves 5-1 and 5-2 does not change. Since the differential pressure before and after increases, it becomes larger than the spring force of the flow control valves 4-1 and 4-2 on the switching valve side, and the opening of the flow control valves 4-1 and 4-2 on the switching valve side decreases. After all, the amount of oil passing through the motor-side flow control valves 5-1 and 5-2 can be controlled to be constant, and the traveling speed can be kept constant according to the command value of the operating valve 11.

Further, as the rotation speed of the prime mover 41 decreases, the amount of oil discharged from the hydraulic pump 42 also decreases. In this case, the rotation speed of the prime mover 41 is detected by the rotation sensor 49 and is input to the controller 17. The controller 17 works so that even if the operation angle of the operation valve 11 is the maximum value, the motor side flow control valve 5-1 , 5-2 are limited to the degree of opening corresponding to the amount of oil discharged from the hydraulic pump 42, so that the traveling speed can be kept constant according to the command value of the operating valve 11 even when descending a slope.

Second Embodiment Finally, a second embodiment of the present invention will be described with reference to FIG. The same parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

An electronic joystick 11A, which takes out an electric signal in response to lever displacement, is used as an operation section which replaces the operation valve 11 of the first embodiment.

In this case, the pressure sensors 12-1 and 12-2 of the first embodiment are not necessary, and the joystick electric signal is directly input to the controller 17. On the other hand, since the joystick electric signal needs to be converted into pilot pressure and applied to both ends of the switching valve 9, electromagnetic proportional pressure reducing valves 13-3 and 13-4 are provided at both ends of the switching valve 9, and the controller 17 supplies electric power. Control signal currents are supplied to the magnetic proportional pressure reducing valves 13-3 and 13-4, respectively, and the pressure reducing valves 13-3 and 13-4 convert the control signals into pilot pressures to act on both ends of the switching valve 9.

[0046]

[Effect of device]

 According to the invention described in claim 1, the motor-side flow control valve, the switching valve-side flow control valve, the check valve, and the control system arranged on the outflow port side of the traveling motor in the traveling hydraulic circuit of the tracked vehicle By the function, the movement of the motor side flow control valve corresponds to the operation angle of the operation part, and the amount of return oil corresponding to the operation angle of the operation part is secured, so smooth running as the operation of the operator is possible. Become.

According to the second aspect of the present invention, the control system limits the maximum opening degree of the motor side flow control valve according to the discharge oil amount of the pump even if the rotation speed of the prime mover decreases. It prevents runaways on downhill slopes and enables safe and smooth running as the operator operates.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a traveling hydraulic circuit for a track-mounted vehicle according to the present invention.

FIG. 2 is an enlarged circuit diagram showing a main part of the same traveling hydraulic circuit.

FIG. 3 is a circuit diagram showing a second embodiment of the traveling hydraulic circuit.

FIG. 4 is a circuit diagram showing a conventional traveling hydraulic circuit for a track-mounted vehicle.

[Explanation of symbols]

 1 Traveling motor 4-1 and 4-2 Flow control valve on the switching valve side 5-1 and 5-2 Flow control valve on the motor side 6-1 and 6-2 Check valve 9 Switching valve 11 Operation valve as an operating part 17 Control system Controller 41 prime mover 42 pump

Claims (2)

[Scope of utility model registration request] 1. A traveling hydraulic circuit of a tracked vehicle for supplying hydraulic oil to a traveling motor via a switching valve for switching a motor rotation direction by an operator's operation from a pump driven by a prime mover. A motor-side flow control valve that is located between the motor and closes the flow from the traveling motor in the direction of the switching valve at the neutral position, and that adjusts the valve opening by an external signal to adjust the passing flow rate; It is arranged on the switching valve side, receives the pressure on the motor side of the motor side flow control valve at one end of the spool, and receives the pressure on the switching valve side of the motor side flow control valve and the spring force at the other end on the motor side. When the force due to the differential pressure between the motor side of the flow control valve and the switching valve side is smaller than the force due to the spring force, the flow in the direction of the switching valve from the traveling motor is allowed, and the force due to the differential pressure is due to the spring force. A flow rate control valve on the switching valve side that limits the flow when the force is larger than the force, and limits the amount of oil passing through so that the force due to the differential pressure balances with the force due to the spring force and is always constant. A check that is provided in the oil passage that connects the motor side of the valve and the switching valve side of the switching valve side flow control valve, and sets the flow from the switching valve in the direction of the traveling motor to the free flow direction and closes the flow in the opposite direction. A traveling hydraulic circuit for a track-mounted vehicle, comprising: a valve; and a control system that associates an operation command signal of an operation section operated by an operator with the opening degree of the motor-side flow control valve. 2. A control system for limiting the maximum opening of the motor side flow control valve according to the number of revolutions of the prime mover and corresponding to the maximum value of the operation command signal of the operating section. A traveling hydraulic circuit for the tracked vehicle described.