JP2545158Y2 - Hydraulic motor drive circuit - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive circuit for a hydraulic motor, and more particularly to a drive circuit for a hydraulic motor for reducing an impact caused by braking of a hydraulic traveling vehicle at a low speed.

[0002]

2. Description of the Related Art FIG. 10 shows a drive circuit of a hydraulic motor of a hydraulic traveling vehicle capable of switching a speed mode between a low speed mode and a high speed mode. A pilot-operated directional control valve 5 and a counterbalance valve 6 are provided in main pipelines 3 and 4 that connect the traveling hydraulic motor 1 and the hydraulic pump 2. The directional control valve 5 is controlled by a pilot operation unit 7, the directional control valve 5 is switched in conjunction with the movement of the operation lever 8, and the discharge oil of the hydraulic pump 2 is supplied to the main pipe via the directional control valve 5 and the counterbalance valve 6. Road 3 or main pipeline 4
From the hydraulic motor 1. The hydraulic motor 1 can change the tilt angle by the operation of the tilt angle adjusting cylinder 9, and the state shown is the low-speed mode, and the rod 9 is biased by the spring 9 b built in the tilt angle adjusting cylinder 9. 9
a contracts into the cylinder, and the tilt angle of the hydraulic motor 1 becomes large. That is, the flow rate per rotation of the hydraulic motor 1 is large and the torque is high.

Further, crossover relief valves 10 and 11 acting in respective directions are provided between the two main pipelines 3 and 4,
A shuttle valve 14 is provided between the bypass lines 12 and 13. Then, a first opening / closing valve 15 that operates in the opening direction by the pilot pressure is provided, and a pipe line to the back pressure chamber 9c of the tilt angle adjusting cylinder 9 is connected to a secondary side of the first opening / closing valve 15. The shuttle valve 14 is provided on the primary side of the first on-off valve 15.
And the return tank 16 are connected. Further, a second on-off valve 17 which operates in the opening direction by energizing the solenoid is provided, and a pilot oil passage 18 is provided on the secondary side of the second on-off valve 17 so that a pilot port of the first on-off valve 15 is provided. And the pilot pump 19 and the return tank 16 are connected to the primary side of the second on-off valve 17.

When a high-speed switching signal is supplied to the solenoid of the second on-off valve from the state shown in the figure, the spool is switched to the position 17a, the second on-off valve is opened, and the spool is discharged from the pilot pump 19. The pilot oil passes through the pilot oil passage 18 and passes through the first on-off valve 15.
To the pilot port. For this reason, the spool of the first on-off valve 15 switches to the position of 15a and the first
The opening / closing valve 15 is opened, and the hydraulic oil from the outlet pipe of the shuttle valve 14 flows into the back pressure chamber 9c of the tilt angle adjusting cylinder 9 and resists the spring 9b built in the tilt angle adjusting cylinder 9. The rod 9a extends out of the cylinder and the hydraulic motor 1
Becomes small. That is, the flow rate per rotation of the hydraulic motor 1 is small and the torque is low, and the high-speed mode is set.

When the body is braked in the high-speed mode, the torque is low because the tilt angle of the hydraulic motor 1 is small, and the crossover relief valves 10 and 11 provided between the main pipelines 3 and 4 are used. Reduces the increase in hydraulic pressure in one of the main pipelines, thereby reducing shock during braking.

[0006]

As described above, the conventional hydraulic traveling vehicle reduces the shock at the time of the vehicle braking in the high-speed mode. However, in the low speed mode, the torque is high because the tilt angle of the hydraulic motor 1 is large, and a large flow of hydraulic oil is discharged in a short time during the braking operation of the body, so that the braking pressure rises sharply. As shown in FIG. 11, the braking pressure is rapidly increased to P _1, the initial reduction in the rate V ₁ of the body is steep and short time Delta] t ₁ until the aircraft stops. Therefore, the shock at the time of the braking of the machine body becomes large, and the fatigue of the operator increases, which causes a decrease in work efficiency.

Therefore, there is a technical problem to be solved in order to improve the operability by reducing the shock at the time of the body braking even in the low-speed mode and to improve the work efficiency by reducing the physical burden on the operator. The present invention aims to solve this problem.

[0008]

DISCLOSURE OF THE INVENTION The present invention has been proposed to achieve the above object. The tilt angle of a hydraulic motor can be changed freely by a tilt angle adjusting cylinder, and the opening direction can be changed by a pilot pressure. A line to the back pressure chamber of the tilt angle adjusting cylinder is provided on the secondary side of the first opening / closing valve that operates, and a first shuttle valve is provided between the two main lines of the hydraulic motor. Te, connects the conduit and the return tank from the outlet of the first shuttle valve to the primary side of the first on-off valve, 且
Switch speed mode to high speed mode or low speed mode
In an operable hydraulic traveling vehicle, a second on-off valve that operates in a closing direction by pilot pressure and a third on-off valve that operates by energizing a solenoid are arranged side by side, and the primary side of each on-off valve is provided. , A second shuttle valve is disposed between two pilot oil passages from a pilot operation unit for controlling a directional control valve of a hydraulic motor, and an outlet of the second shuttle valve is provided. And a pilot port of the second on-off valve, and a pilot oil passage on the secondary side of the second and third on-off valves is connected by a third shuttle valve. Connecting the outlet to the pilot port of the first on-off valve, thus:
When the hydraulic operation of the hydraulic motor is performed by the pilot operation unit during low-speed running of the body, hydraulic fluid is led out to the back pressure chamber of the tilt angle adjusting cylinder to change the tilt angle of the hydraulic motor to a small value. It is intended to provide a drive circuit for a hydraulic motor, characterized in that the drive circuit is configured to perform the following.

[0009]

[Function] When the pilot operating unit is returned to the neutral position to brake the aircraft traveling in the low speed mode, the pilot oil from the pilot pump is shut off and the directional control valve of the hydraulic motor returns to the neutral position. I do. When that happens,
The derivation of pilot pressure from the second shuttle valve to the pilot port of the second on-off valve is stopped, and the second on-off valve is opened. Then, the pilot oil passes through the second on-off valve, and is led out to the pilot port of the first on-off valve via the third shuttle valve. Accordingly, the spool of the first on-off valve moves in the opening direction, and the hydraulic oil is led out to the back pressure chamber of the tilt angle adjusting cylinder via the first shuttle valve provided between the two main pipelines. , The tilt angle of the hydraulic motor changes to a small value.

Therefore, at the time of body braking in the low speed mode,
Since the flow rate per rotation of the hydraulic motor becomes small and the torque becomes low, the braking torque decreases, the time until the braking pressure rises becomes slightly longer, and the shock at the time of body braking is reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to FIGS. For convenience of explanation, the same components as those of the related art will be described at the same time. FIG. 1 shows a drive circuit of a hydraulic motor of a hydraulic traveling vehicle in which a speed mode can be manually switched between a low speed mode and a high speed mode by a switch, and a main line connecting a hydraulic motor 21 for traveling and a hydraulic pump 22. A pilot-operated directional control valve 25 and a counterbalance valve 26 are provided at 23 and 24. The directional control valve 25 is controlled by a pilot operation unit 27, and interlocks with the operation of the operation lever 28 to control the directional control valve 2
5 is switched, and the discharge oil of the hydraulic pump 22 is supplied to the main pipeline 2 via the directional control valve 25 and the counterbalance valve 26.
3 or from the main line 24 to the hydraulic motor 21.
The hydraulic motor 21 can change the tilt angle by the operation of the tilt angle adjusting cylinder 29, and the state shown is the low speed mode, and the rod 29 is urged by the spring 29b built in the tilt angle adjusting cylinder 29. 29a contracts into the cylinder, and the tilt angle of the hydraulic motor 21 becomes large. That is, the flow rate per rotation of the hydraulic motor 21 is large and the torque is high.

Further, crossover relief valves 30 and 31 acting in the respective directions are provided between the two main lines 23 and 24, and a first shuttle valve 34 is provided between the bypass lines 32 and 33.
Is arranged. Then, a first opening / closing valve 35 which operates in the opening direction by the pilot pressure is provided.
5, the back pressure chamber 2 of the tilt angle adjusting cylinder 29
The pipe to 9c is connected, and the outlet pipe of the first shuttle valve 34 and the return tank 36 are connected to the primary side of the first on-off valve 35.

On the other hand, the pilot operating section 27 rotates the operating lever 28 in either the forward side or the reverse side of the body, so that the pilot pump 39a is connected to the pilot oil passage 40 through the pilot valve 37 or 38. Or 41
It is configured to derive pilot oil to the engine. The pilot oil passage 40 is connected to one pilot port 42 of the directional control valve 25, and the pilot oil passage 41 is connected to the other pilot port 43 of the directional control valve 25. A bypass oil passage 44 is provided between 41 and a second shuttle valve 45 is provided in the middle of the bypass oil passage 44.

Here, a second opening / closing valve 46 that operates in the closing direction by the pilot pressure and a third opening / closing valve 47 that operates in the opening direction by supplying a switching signal to the high-speed mode to the solenoid are provided in parallel. And the respective on-off valves 46
And 47 are connected to a pilot pump 39b and a return tank 36. The outlet of the second shuttle valve 45 is connected to the pilot port of the second on-off valve 46, and the pilot oil passages on the secondary side of the second and third on-off valves 46 and 47 are connected to the third oil passage. The connection is made by a shuttle valve 48, and the outlet of the third shuttle valve 48 is connected to the pilot port of the first on-off valve 35.

Next, the operation of the hydraulic motor drive circuit according to the present invention will be described. As shown in FIG. 1, when the aircraft is stopped on a flat ground and the switch is switched to the low-speed mode, the solenoid of the third on-off valve 47 is not energized, and the spool of the third on-off valve 47 is not energized. At the position 47b, and the third on-off valve 47 is closed. Further, since the operation lever 28 of the pilot operation section 27 is in the neutral position, the pilot pressure from the second shuttle valve 45 is not led out to the pilot port of the second on-off valve 46, and the second on-off valve 4
6 is in the position 46a and the second on-off valve 46
Is open. Therefore, the pilot oil from the pilot pump 39b is led to the pilot port of the first on-off valve 35 through the second on-off valve 46 and the third shuttle valve 48, and the spool of the first on-off valve 35 is moved to the position 35a. Accordingly, the first on-off valve 35 is open. When the aircraft is stopped on a flat ground, no hydraulic pressure is generated in the two main pipelines 23 and 24 of the hydraulic motor 21, so the tilt angle is adjusted from the first shuttle valve 34 via the first on-off valve 35. Hydraulic fluid is not drawn out to the back pressure chamber 29c of the cylinder 29, the rod 29a contracts into the cylinder by the bias of the spring 29b built in the cylinder 29 for adjusting the tilt angle, and the tilt angle of the hydraulic motor 21 increases. It has become. That is, the flow rate per rotation of the hydraulic motor 21 is large and the torque is high, and the hydraulic motor 21 is in a state suitable for starting the aircraft.

Here, as shown in FIG. 2, if the operating lever 28 of the pilot operating section 27 is rotated in either the forward side or the backward side of the fuselage to start the fuselage, the pilot valve 37 or 38 is started. The pilot oil is led out from the pilot pump 39a to the pilot oil passage 40 or 41 via the pilot oil. Then, a pilot pressure is applied to one of the pilot ports 42 or 43 of the direction control valve 25, the spool of the direction control valve 25 is switched, hydraulic fluid is drawn out to the main pipeline 23 or 24, and the hydraulic motor 21 rotates. At that time, pilot pressure is applied from the second shuttle valve 45 to the pilot port of the second on-off valve 46, and the spool of the second on-off valve 46 is switched to the position 46b and closed. Therefore, the second on-off valve 46 and the third on-off valve 47
Is closed, the pilot oil of the pilot pump 39b is not discharged to the pilot port of the first on-off valve 35, and the spool of the first on-off valve 35 is switched to the position 35b and closed. For this reason, the hydraulic oil led out from the bypass line 32 or 33 via the first shuttle valve 34 is closed by the first on-off valve 35 and the tilt angle adjusting cylinder 2
No hydraulic oil is drawn out to the back pressure chamber 29c of FIG. 9, the tilt angle of the hydraulic motor 21 is kept large, and the aircraft can be easily started in the low speed mode.

Next, when the switch is switched to the high-speed mode while the vehicle is traveling in the low-speed mode, a high-speed switching signal is supplied to the solenoid of the third on-off valve 47 as shown in FIG. The spool 47 is switched to the position 47a, and the third on-off valve 47 is opened. Accordingly, the pilot oil of the pilot pump 39b passes through the third on-off valve 47 and passes through the third shuttle valve 48 to the first oil.
The spool of the first on-off valve 35 is switched to the position 35a and opened. For this reason, the first bypass line 32 or 33
The hydraulic oil led out through the shuttle valve 34 is led out to the back pressure chamber 29c of the tilt angle adjusting cylinder 29, and the rod 29a is pressed against the bias of the spring 29b of the tilt angle adjusting cylinder 29. The hydraulic motor 21 protrudes outside the cylinder, and the tilt angle of the hydraulic motor 21 changes to a small value. In other words, the flow rate per rotation of the hydraulic motor 21 becomes small and the torque becomes low, so that the aircraft is in a state suitable for high-speed traveling.

On the other hand, when the fuselage is stopped on a flat ground and the switch is switched to the high-speed mode, the operating lever 28 of the pilot operating section 27 is turned in either the forward or backward direction of the fuselage. Then, as shown in FIG. 4, the pilot pump 39
The pilot oil is led out from a to the pilot oil passage 40 or 41. Then, the pilot pressure is applied to one of the pilot ports 42 or 43 of the directional control valve 25 to switch the spool of the directional control valve 25, and the main line 23 or 2
The hydraulic oil is led out to 4 and the hydraulic motor 21 rotates. At that time, pilot pressure is applied from the second shuttle valve 45 to the pilot port of the second on-off valve 46, and the spool of the second on-off valve 46 is switched to the position 46b and closed. Since the switch has been switched to the high-speed mode, a high-speed switching signal is supplied to the solenoid of the third on-off valve 47, and the spool of the third on-off valve 47
Switching to the position a, the third on-off valve 47 is opened. Therefore, the pilot oil of the pilot pump 39b passes through the third on-off valve 47, is led out to the pilot port of the first on-off valve 35 via the third shuttle valve 48,
The spool of the first on-off valve 35 is switched to the position 35a and opened.

At this time, since the tilt angle of the hydraulic motor 21 is still large, the torque is high, and the vehicle can be easily started even if the switch is switched to the high-speed mode. Then, as the flow rate of the hydraulic oil led to the main line 23 or 24 increases, the bypass line 32
Alternatively, the hydraulic oil derived from 33 or 33 via the first shuttle valve 34 is guided to the back pressure chamber 29c of the tilt angle adjusting cylinder 29 and resists the bias of the spring 29b of the tilt angle adjusting cylinder 29. As a result, the rod 29a projects outside the cylinder, and the tilt angle of the hydraulic motor 21 changes to a small value. In other words, the flow rate per rotation of the hydraulic motor 21 becomes small and the torque becomes low, so that the aircraft is in a state suitable for high-speed traveling.

Here, if the operating lever 28 of the pilot operating section 27 is turned to the neutral position in order to brake the body,
As shown in the figure, the pilot oil is no longer led from the pilot pump 39a to the pilot oil passage 40 or 41,
The direction control valve 25 returns to the neutral position. In that case, the pilot pressure is not led out from the second shuttle valve 45 to the pilot port of the second on-off valve 46,
The spool of the on-off valve 46 is switched to the position 46a and opened. Since the pilot oil from the pilot pump 39b is always drawn to the pilot port of the first on-off valve 35, the spool of the first on-off valve 35
At position a, the first on-off valve 35 is opened, the rod 29a of the tilt angle adjusting cylinder 29 projects outside the cylinder, and the tilt angle of the hydraulic motor 21 is kept small.
That is, when the aircraft is braked in the high-speed mode, the hydraulic motor 21
Since the flow rate per rotation is small and the torque is low, the braking torque naturally becomes minimum even if a braking pressure equivalent to that at low speed is generated. Therefore, the shock at the time of the vehicle braking is reduced as compared with the case of a low speed with a high braking torque.

On the other hand, if the vehicle continues traveling in the low-speed mode shown in FIG. 2 and the operation lever 28 of the pilot operation section 27 is turned to the neutral position in order to brake the aircraft in the low-speed mode, as shown in FIG. Then, the pilot oil is no longer led from the pilot pump 39a to the pilot oil passage 40 or 41, and the direction control valve 25 returns to the neutral position. In that case, the pilot pressure from the second shuttle valve 45 to the pilot port of the second on-off valve 46 is not derived,
The spool of the second on-off valve 46 switches to the position 46a and is opened. For this reason, the pilot oil of the pilot pump 39b passes through the second on-off valve 46, is led out to the pilot port of the first on-off valve 35 via the third shuttle valve 48, and the spool of the first on-off valve 35 Is switched to the position 35a and released. Therefore, the hydraulic oil derived from the bypass line 32 or 33 through the first shuttle valve 34 is supplied to the back pressure chamber 29 of the tilt angle adjusting cylinder 29.
c of the cylinder 29 for adjusting the tilt angle.
The rod 29a protrudes out of the cylinder against the urging of the hydraulic motor 21, and the tilt angle of the hydraulic motor 21 becomes small.

[0022] That is, the flow rate per rotation of the hydraulic motor 21 has a low torque at small during aircraft braking, as shown in FIG. 7, it takes a little time for the brake pressure rises to P _2, the body initial drop velocity V ₁ is a slow and prolonged time Delta] t ₂ until the aircraft stops. Therefore, even when the vehicle is traveling in the low speed mode, the shock at the time of the vehicle braking is reduced.

When the body is stopped on a slope such as a hill, the rod 29a of the tilt angle adjusting cylinder 29 projects out of the cylinder by its own weight, and as shown in FIG. Although the tilt angle is small and the mode is in the high-speed mode, if the operation lever 28 of the pilot operation unit 27 is rotated in either the forward side or the reverse side of the body at the time of starting the body, FIG. Returning to the state shown in (1), the aircraft can be started.

FIG. 8 shows a second embodiment, in which the third opening / closing valve 47 shown in FIG. 1 is operated in the closing direction by energizing a solenoid with a switching signal for switching to a low speed mode. An on-off valve 49 is provided. In the case of such a configuration,
If the switch is switched to the low-speed mode, the fourth on-off valve 4
The spool 9 is switched to the position 49b, and the operation is the same as that of the hydraulic circuit having the configuration shown in FIG.

FIG. 9 shows a third embodiment, which shows a drive circuit of a hydraulic motor of a hydraulic traveling vehicle of automatic switching between high speed and low speed, instead of the 4-port counterbalance valve 26 shown in FIG. , A six-port counterbalance valve 50, and one port of a mechanical brake 52 is connected to a newly provided oil passage 51. Then, one pilot port of the load sensing on-off valve 53 and the other port of the mechanical brake 52 are connected by an oil passage 54, and the other pilot port of the load sensing on-off valve 53 is connected to a third shuttle valve. Connect to 48 outlets. or,
As in the hydraulic circuit shown in FIG.
The back pressure chamber 29 of the tilt angle adjusting cylinder 29
The outlet line of the first shuttle valve 34 and the return tank 36 are connected to the primary side of the load sensing on-off valve 53.

The drive circuit of the hydraulic motor having the structure shown in FIG. 9 operates in the same manner as the hydraulic circuit having the structure shown in FIG. 1, and therefore a detailed description is omitted. The present invention can be variously modified without departing from the spirit of the present invention, and it goes without saying that the present invention extends to the modified one.

[0027]

According to the present invention, as described in detail in the above-described embodiment, the first opening / closing valve is opened when the airframe running in the low speed mode is braked, and is provided between the two main pipelines. From the first shuttle valve, the hydraulic oil passes through the first on-off valve and is led out to the back pressure chamber of the tilt angle adjusting cylinder. Therefore,
The tilt angle of the hydraulic motor is reduced, and the flow per rotation of the hydraulic motor is reduced, resulting in lower torque.

Therefore, various factors such as an increase in braking pressure and a decrease in shock at the time of body braking are reduced, operability is improved, and physical fatigue of the operator is reduced to improve work efficiency. It is a device of practical value.

[Brief description of the drawings]

FIG. 1 is a drive circuit diagram of a hydraulic motor in a low-speed mode of a hydraulic traveling vehicle in which a high-speed low-speed manual switching is performed when an airframe is stopped according to an embodiment of the present invention;

FIG. 2 is a drive circuit diagram of a hydraulic motor in a state in which the vehicle starts moving in a low-speed mode.

FIG. 3 is a drive circuit diagram of a hydraulic motor in a state where a switch is switched from a low-speed mode to a high-speed mode.

FIG. 4 is a drive circuit diagram of a hydraulic motor in a state in which the aircraft starts in a high-speed mode.

FIG. 5 is a drive circuit diagram of the hydraulic motor in a state where the body is braked in a high-speed mode.

FIG. 6 is a drive circuit diagram of a hydraulic motor in a state where the body is braked in a low-speed mode.

FIG. 7 is a graph showing the relationship between braking pressure, speed, and time during body braking in a low-speed mode.

FIG. 8 shows a second embodiment of the present invention, and is a drive circuit diagram of the hydraulic motor in a state in which the machine is stopped in a low-speed mode.

FIG. 9 shows a third embodiment of the present invention, and is a drive circuit diagram of a hydraulic motor in a low-speed mode of a hydraulic traveling vehicle with automatic switching between high speed and low speed when the body is stopped.

FIG. 10 is a diagram showing a conventional example, and is a drive circuit diagram of a hydraulic motor in a state in which the body is stopped in a low-speed mode of a hydraulic traveling vehicle with high-speed low-speed manual switching.

FIG. 11 shows a conventional example, and is a graph showing the relationship between braking pressure, speed, and time during body braking in a low-speed mode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Hydraulic motor 22 Hydraulic pump 23, 24 Main pipeline 25 Direction control valve 27 Pilot operation part 29 Tilting angle adjustment cylinder 29c Back pressure chamber 34 First shuttle valve 35 First on-off valve 36 Return tank 39a Pilot pump 39b Pilot Pump 40, 41 Pilot oil passage 45 Second shuttle valve 46 Second on-off valve 47 Third on-off valve 48 Third shuttle valve

Claims (1)

(57) [Scope of request for utility model registration] The tilt angle of a hydraulic motor is made variable by a tilt angle adjusting cylinder, and the tilt angle adjusting cylinder is provided on the secondary side of a first opening / closing valve which is operated in an opening direction by pilot pressure. A pipe to the pressure chamber, a first shuttle valve disposed between the two main pipes of the hydraulic motor, and a pipe from an outlet of the first shuttle valve on a primary side of the first on-off valve. Connect the road and the return tank, and in high speed mode or low speed
Traveling vehicle that can be operated by switching the speed mode to the speed mode
, A second on-off valve that operates in a closing direction by pilot pressure and a third on-off valve that operates by energizing a solenoid are provided side by side, and a pilot pump and a return tank are provided on the primary side of each on-off valve. And a second shuttle valve is disposed between two pilot oil passages from a pilot operation unit for controlling a directional control valve of a hydraulic motor, and an outlet of the second shuttle valve is connected to the second opening / closing valve. A pilot port of the valve is connected, a pilot oil passage on the secondary side of the second and third on-off valves is connected by a third shuttle valve, and an outlet of the third shuttle valve is connected to the first shuttle valve. It is connected to the pilot port of the on-off valve, and thus, when the hydraulic operation of the hydraulic motor is performed by the pilot operation unit during low-speed running of the body, hydraulic fluid is led out to the back pressure chamber of the tilt angle adjusting cylinder. Oil To change the tilt angle of the motor in small
Drive circuit of the hydraulic motor, characterized in that is configured to be able.