JPH09323562A - Hub clutch control device for hydraulic driving wheel of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the rotating connection between a hydraulic motor and a hydraulic driving wheel before the main hydraulic pump of a hydraulic driving mechanism is rotated by connecting an actuator for driving a hub clutch by the discharge oil pressure of internal lubricating oil of the hydraulic motor against the force of a spring. SOLUTION: When a clutch 3 is interrupted to operate a shift lever to low speed stage, and the clutch 3 is then connected, the rotation of the output shaft 7 of a gear reducer 4 is transmitted to a mechanical driving wheel. The electromagnetic coil 36a of an electromagnetic directional selector valve 36 is also excited thereby. The pressure oil is supplied from a sub-hydraulic pump 15 to the right end chamber of the actuator 37 through the electromagnetic directional selector valve 36 to move a rod 38 to the left. The pressure oil is carried from a main hydraulic pump 12 to a lower pressure oil passage 13 through a high pressure oil passage 14 and hydraulic motors 41, 41a to normally rotate a hydraulic driving wheel. Since the discharge quantity of the main hydraulic pump 12 is gradually increased according to the movement of the rod 38 to the left, and the rotating speeds of the hydraulic motors 41, 41a are raised according to the discharge quantity, a vehicle can be smoothly started.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanical / hydraulic drive mechanism (H) for vehicles such as construction machinery, agricultural machinery, and various work vehicles.
ST) hydraulic drive wheel hub clutch control device,
In particular, even if the main hydraulic pump of the hydraulic drive mechanism is not rotating, the rotation of the main shaft of the hydraulic motor and the hub of the hydraulic drive wheels can be connected / disconnected using the hydraulic pressure and spring force. The present invention relates to a hub clutch control device for drive wheels.

[0002]

2. Description of the Related Art A sub-hydraulic pump, together with a main hydraulic pump,
In a hydraulic drive mechanism of a vehicle driven by a transmission connected to an engine, a hub clutch arranged at an outer end portion of a hub of a hydraulic drive wheel is manually operated, or a main shaft of a hydraulic motor and a hydraulic drive wheel are connected. It is common to connect / disconnect the hydraulic motor and the hydraulic drive wheel by utilizing the relative rotation with the hub. However, the hub clutch cannot be connected or disconnected while the vehicle is running, and the manual operation of the hub clutch outside the vehicle lacks convenience. In addition, if the hydraulic drive wheels are driven to the maximum speed of the vehicle, a large capacity variable displacement type main hydraulic pump or hydraulic motor is required, and there is a problem in durability and reliability.

For example, in the hydraulic drive mechanism for a vehicle disclosed in Japanese Patent Application Laid-Open No. 6-156120, when the main hydraulic pump is started, hydraulic pressure is generated in a hydraulic circuit connecting the main hydraulic pump and the hydraulic motor, and the main shaft of the hydraulic motor. The hub clutch is automatically connected between the hub and the hub of the hydraulic drive wheel, and when the hydraulic pressure of the hydraulic circuit is released, the hub clutch is automatically shut off by the force of the spring. However, when the vehicle starts moving, the hydraulic pressure increases after the main hydraulic pump rotates, and a considerable time delay occurs before the hub clutch between the main shaft of the hydraulic motor and the hub of the hydraulic drive wheel is connected.

Further, in a mechanical / hydraulic drive mechanism that obtains power from a power take-out mechanism incorporated in a gear transmission of a vehicle to drive a main hydraulic pump, the vehicle is on stand-by standby (while the clutch is shut off). It was not possible to connect the hub clutch between the main shaft of the hydraulic motor and the hub of the hydraulic drive wheels because the main hydraulic pump does not rotate.

In any case, when there is a large time delay until the main shaft of the hydraulic motor is rotationally coupled to the hub of the hydraulic drive wheels when the vehicle starts moving, the mechanical drive wheels are driven first on the icy road, causing slippage. May occur.

[0006]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the object of the present invention is to solve the problems described above even when the main hydraulic pump is stopped when the vehicle is starting.
Hub clutch control of the hydraulic drive wheel of the vehicle, where the hydraulic pressure of the hydraulic circuit connecting the main hydraulic pump and the hydraulic motor rises quickly, and the hub clutch between the main shaft of the hydraulic motor and the hub of the hydraulic drive wheel is automatically connected. To provide a device.

[0007]

In order to solve the above problems, the structure of the present invention comprises a mechanical drive wheel driven by an engine through a gear transmission, a main hydraulic pump driven by the engine, and The pair of hydraulic motors driven by the pressure oil from the main hydraulic pump, the hydraulic drive wheels driven by the hydraulic motor, and the hydraulic pressure of the hydraulic circuit connecting the main hydraulic pump and the hydraulic motor are compensated. A sub-hydraulic pump, a hub clutch for connecting / disconnecting the rotation of the hydraulic motor and the hub of the hydraulic drive wheel, and an actuator for driving the hub clutch, and the actuator is resistant to the force of a spring. The hydraulic motor is driven to the connection position by the discharge pressure of the internal lubricating oil.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The hub clutch is composed of dog teeth provided on the tip of the transmission shaft and dog teeth provided on the inner peripheral surface of the hub of the hydraulic drive wheel, and is connected / disconnected by the actuator. The actuator forms an oil chamber between the end of the main shaft of the hydraulic motor and the base end of the transmission shaft spline-fitted to the main shaft.

Driving the auxiliary hydraulic pump directly by an electric motor or an engine, connecting a pressure accumulator to the hydraulic circuit of the hydraulic motor, or connecting a high-pressure air tank to a sealed oil tank connected to the hydraulic circuit of the hydraulic motor. By this, even when the main hydraulic pump is stopped when the vehicle starts, the hydraulic pressure of the hydraulic circuit of the hydraulic motor is quickly increased, the pressure oil of the hydraulic circuit is supplied to the actuator, the hub clutch is connected, and the hydraulic motor and hydraulic drive wheels are connected. Get the rotational coupling of.

[0010]

1 is a side sectional view of a hub clutch mechanism for a hydraulic drive wheel of a vehicle, FIG. 2 is an enlarged side sectional view of an actuator for driving the hub clutch mechanism, and FIG. 3 is a hub clutch for the hydraulic drive wheel. It is a hydraulic circuit diagram of a control device. As shown in FIG. 3, a manual gear transmission 4 is connected to the engine 2 through a clutch 3, and the power of the engine 2 is driven from an output shaft 7 of the gear transmission 4 to, for example, front wheels by a known mechanical drive. It is transmitted to the mechanism. The hydraulic drive mechanism for driving the rear wheels is a known power take-off mechanism 11 attached to the gear transmission 4.
It is getting power from. The power take-out mechanism 11 is configured such that a gear 9 can mesh with the gear 6 of the intermediate shaft 5 of the gear transmission 4 and the gear 10a of the output shaft 10 by an electromagnetic actuator 8 or the like. Output shaft 10 of power take-out mechanism 11
A variable displacement main hydraulic pump 12 is connected to.

The main hydraulic pump 12 is constructed to suck oil from the low pressure passage 13 and supply it to the high pressure passage 14.
When the oil pressure in the low pressure passage 13 or the high pressure passage 14 becomes abnormally high, the oil pressure is released to the oil tank 26 via the relief valve 64 or 64a, the passage 65, and the relief valve 19 having a high valve opening pressure, but most of the pressure oil is It flows from the passage 65 to the high pressure passage 14 or the low pressure passage 13 via the check valve 66a or 66. But,
When the main hydraulic pump 12 is rotated in the reverse direction, the passages 13 and 14 are
The relationship of hydraulic pressure is reversed. The high-pressure passage 14 is a reversibly rotatable hydraulic motor 4 coupled to the axles of hydraulic drive wheels.
1, 41a are connected to the inlet ports, and the low pressure passage 13 is connected to the outlet ports of the hydraulic motors 41, 41a. As described above, the main hydraulic pump 12 and the hydraulic motors 41, 41a
Is hydraulically coupled to the pressure oil discharged from the main hydraulic pump 12, and the high pressure passage 14, the hydraulic motors 41, 41a,
When flowing into the low-pressure passage 13, the hydraulic motors 41 and 41a are normally rotated to drive the hydraulic drive wheels in the forward direction.

In order to obtain a smooth start of the vehicle by the hydraulic drive mechanism, there is provided pump control means C for gradually increasing the discharge amount of the main hydraulic pump 12 from 0 and gradually increasing the rotational speeds of the hydraulic motors 41, 41a. Be prepared. The pump control means C includes an actuator 37 for controlling a flow rate of the main hydraulic pump 12 and driving a control member (for example, a swash plate) for switching the flow direction, and an electromagnetic directional control valve 36 for controlling a hydraulic circuit of the actuator 37. Composed of.

The actuator 37 has a piston 39 fitted in a cylinder 40 to define a left end chamber and a right end chamber, and a rod 38 protruding from the piston 39 to the outside is used as a main hydraulic pump 12.
It is connected to the control member of. When the electromagnetic directional control valve 36 is in the neutral position for returning the pressure oil from the auxiliary hydraulic pump 15 to the oil tank 26, the piston 39 is returned to the neutral position by the pair of springs, and the discharge amount of the main hydraulic pump 12 becomes zero. . When the electromagnetic coil 36a of the electromagnetic directional control valve 36 is energized, it switches to a position where the pressure oil is supplied to the right end chamber of the cylinder 40, the piston 39 moves leftward, and the main hydraulic pump 12 rotates normally. When the electromagnetic coil 36b of the electromagnetic directional control valve 36 is energized, it switches to a position where the pressure oil is supplied to the left end chamber of the cylinder 40, the piston 39 moves to the right, and the main hydraulic pump 12 reverses. The discharge amount of the main hydraulic pump 12 increases according to the moving amount from the neutral position of the piston 39.

In order to release the fluid connection between the main hydraulic pump 12 and the hydraulic motors 41, 41a at the time of starting and shifting the vehicle, the bypass passage 27 connecting the low pressure passage 13 and the high pressure passage 14 is normally closed. The electromagnetic on-off valve 27a of the mold is inserted and connected. When the electromagnetic opening / closing valve 27a is energized, it switches to the open position.

According to the present invention, when the pressure oil from the main hydraulic pump 12 passes through the respective hydraulic motors 41, 41a when the vehicle starts, the oil for lubricating the insides of the hydraulic motors 41, 41a against the force of the springs. The hub clutches B are connected by the hydraulic pressure. As shown in FIG. 1, the hydraulic motor 4
1, the flange portion 48 is connected to the nut 63 by a bolt (not shown), and the main shaft 53 is spline-fitted to the base end portion of the axle or the transmission shaft 51. Transmission shaft 5
No. 1 is fitted and inserted into the hollow shaft portion 62 of the nut 63, and the toothed teeth 59 similar to a gear are fitted and supported on the serration shaft portion 51a at the tip. The dog tooth 59 is configured to be able to mesh with the dog tooth 55a formed on the inner peripheral surface of the tubular body 60. However, normally, the spring 58 interposed between the spring seat 57a and the dog tooth 59 is used.
The dog tooth 59 is separated from the dog tooth 55a by the force of.

The hub 55 of the hydraulic drive wheel is supported by a pair of radial bearings 61 on a shaft portion 62 of a knuckle 63, and a wheel disc is connected to a flange portion 55b. An annular flange 60a at the end of the hub 55,
The tubular body 60 provided with the dog teeth 55a, the tubular body 57 supporting the spring seat 57a, and the lid 56 are integrally coupled by a plurality of bolts (not shown). The hydraulic motor 41a is similarly connected to the hub 55 of the right hydraulic drive wheel.

As shown in FIGS. 2 and 3, each actuator A includes a main shaft 53 and a transmission shaft 51 of each hydraulic motor 41, 41a.
Is formed between Main shaft 5 of hydraulic motors 41 and 41a
The spline shaft portion 53a formed in 3 is fitted into the spline hole 51b at the base end portion of the transmission shaft 51. The oil chambers 28, 28a are defined by fitting the pistons 30, 30a formed at the base end portion of the transmission shaft 51 into the cylinders 29, 29a (FIG. 3) formed at the tip end portion of the main shaft 53. Hydraulic motor 4
The main shaft 53 is provided with an axial passage 53b for guiding the lubricating oil inside the 1, 41a to the oil chambers 28, 28a. The passage 53b extending from each hydraulic motor 41, 41a includes a check valve 71,
It is possible to communicate with the passage 13 via 71a and to the passage 14 via the check valves 72, 72a. In order to hold each hub clutch B in the cutoff state, the oil chamber 2 of each actuator A
8, 28a can be communicated with the oil tank 26 via a normally-closed electromagnetic opening / closing valve 77.

Each hub clutch B has a transmission shaft 5 as described above.
1 and the hub 55 of the hydraulic drive wheel, when hydraulic pressure is generated in the lubricating oil inside each of the hydraulic motors 41 and 41a, the lubricating oil passes through the axial passage 53b of the main shaft 53 and the oil chamber 28, 28a, the pistons 30 and 30a are moved to the spring 5
8,58a to overcome the force of movement
0a and the transmission shaft 51 integral with each other, and the dog tooth 59 is moved to the dog tooth 5
5a is engaged. Thus, each hydraulic motor 41, 41
The rotation of the main shaft 53 of a is transmitted to the hub 55 via the transmission shaft 51 and the hub clutch B. When the oil pressure of the lubricating oil inside each hydraulic motor 41, 41a becomes low, the transmission shaft 51 is pushed back by the force of the springs 58, 58a, and the dog tooth 59a of the transmission shaft 51 and the dog tooth 55a of the hub 55 of the hydraulic drive wheel. Is disengaged.

The operation of the hub clutch control device for hydraulically driven wheels according to the present invention will now be described. The gear 9 of the power take-off mechanism 11 is connected to the gear 6 and the gear 1 by the actuator 8.
It meshes with 0a. When a start switch or actuating switch (not shown) is closed when the vehicle starts, the electromagnetic opening / closing valve 27a opens and the high pressure passage 14 and the low pressure passage 13 communicate with each other, so that the main hydraulic pump 12 and the hydraulic motors 41, 41a.
Is released from the fluid coupling, and the operation of the shift lever is not hindered by the interference between the mechanical drive mechanism and the hydraulic drive mechanism.
Next, when the clutch 3 is cut off and the shift lever is operated to the low speed stage to connect the clutch 3, the rotation of the output shaft 7 of the gear transmission 4 is transmitted to the mechanical drive wheels. At the same time, the electromagnetic coil 36a of the electromagnetic directional control valve 36 is excited and the spool moves to the left. Pressure oil is supplied from the sub-hydraulic pump 15 to the right end chamber of the actuator 37 via the electromagnetic directional control valve 36, and the rod 38 moves leftward. Main hydraulic pump 12
From the pressure oil to the low pressure passage 13 through the high pressure passage 14 and the hydraulic motors 41 and 41a, and the hydraulic drive wheels are normally rotated by the hydraulic motors 41 and 41a. As the rod 38 of the actuator 37 moves to the left, the discharge amount of the main hydraulic pump 12 gradually increases, and the hydraulic motors 41, 4 move in accordance with the discharge amount.
Since the rotation speed of 1a is increased, a smooth start of the vehicle can be achieved. When the brake is applied while the vehicle is moving forward, the rotation of the hydraulic motors 41, 41a is suppressed, and the hydraulic pressure in the high pressure passage 14 is released to the oil tank 26 through the relief valve 64a, the passage 65, the relief valve 19, and the passage 16. Most of the pressure oil in the high pressure passage 14 flows to the low pressure passage 13 via the relief valve 64a, the passage 65, and the check valve 66.

When the vehicle is moving backward, the electromagnetic coil 36b of the electromagnetic directional control valve 36 is energized and the spool moves to the right. Pressure oil is supplied from the sub-hydraulic pump 15 to the left end chamber of the cylinder 40 via the electromagnetic directional control valve 36, and the rod 38 moves to the right. The main hydraulic pump 12 reversely rotates, the pressure oil flows to the passage 13, the hydraulic motors 41, 41a, and the passage 14, and the hydraulic drive wheels are reversely rotated by the hydraulic motors 41, 41a.
The vehicle moves backward. If you apply the brakes while the vehicle is moving backwards,
The rotation of the hydraulic motors 41, 41a is suppressed, and the oil pressure in the passage 13 is released to the oil tank 26 via the relief valve 64, the passage 65, the relief valve 19, and the passage 16, but most of the pressure oil in the passage 13 is released. 64, passage 65, check valve 66a, and passage 14
Flows to

In the embodiment shown in FIG. 4, when the vehicle starts, pressure oil is supplied from the auxiliary hydraulic pump 43 driven by the electric motor 42 to the hydraulic circuits of the hydraulic motors 41, 41a via the check valve 47. Before the main hydraulic pump 12 of the hydraulic drive mechanism starts to rotate, it is possible to drive the hydraulic motors 41 and 41a and connect the hub clutch B. The variable displacement main hydraulic pump 12 connected to the output shaft 10 of the power takeoff mechanism 11 is configured to suck oil from the low pressure passage 13 and supply the oil to the high pressure passage 14. When the hydraulic pressure in the high pressure passage 14 becomes abnormally high, the hydraulic pressure is released by the relief valve 24.
And is released to the low pressure passage 13. Conversely, the low pressure passage 13
When the hydraulic pressure of the hydraulic pressure becomes abnormally high, the hydraulic pressure of the passage 21 and the check valve 2 increases.
3 is released to the high-pressure passage 14, and at the same time, the passages 21 and 2 are released.
2, 20, the relief valve 19, and the passage 16 are released to the oil tank 26.

The sub hydraulic pump 15 is integrally connected to the main hydraulic pump 12, sucks oil from the oil tank 26 through the passage 16 and supplies the oil to the main hydraulic pump 12,
It suppresses the decrease in hydraulic pressure due to oil leakage in the hydraulic circuit, and compensates the hydraulic pressure. When the discharge hydraulic pressure of the auxiliary hydraulic pump 15 becomes abnormally high, the hydraulic pressure is released to the oil tank 26 through the passage 17, the filter 18, the passage 20, the relief valve 19 and the passage 16.

The low-pressure passage 13 and the high-pressure passage 14 are connected to the left and right hydraulic drive wheel axles via an electromagnetic switching valve 25 for switching between forward and backward movement, and the hydraulic pressures of the reversible / variable displacement type hydraulic motors 41, 41a are respectively connected. Connected to the circuit. Each hydraulic motor 4
The main shafts 1, 41a are rotatably connected to the axles of each hydraulic drive wheel by a hub clutch B, and the hub clutch B is connected and disconnected by an actuator A. When the electromagnetic switching valve 25 is in the forward position shown, the high pressure passage 34 is connected to the inlet ports of the hydraulic motors 41 and 41a, and the low pressure passage 33 is connected to the outlet ports of the hydraulic pumps 41 and 41a. The oil that lubricates the inside of each hydraulic motor 41, 41a is limited to the throttle 31, 31a or the throttle 32, 32a.
It is configured to flow to the low pressure passage via a. In order to release the fluid connection between the main hydraulic pump 12 and the hydraulic motors 41, 41a during the speed change operation, the high pressure passage 34 and the low pressure passage 3
In the bypass passage 35 connecting to the
7a is inserted and connected. The solenoid on-off valve 27a is a clutch 3
During the shut-off operation of 1), the high pressure passage 34 and the low pressure passage 33 communicate with the oil tank 26 by being excited and opened.

A sub-hydraulic pump 43 driven by an electric motor 42 is provided in order to quickly start up the hydraulic circuits of the hydraulic motors 41, 41a when the vehicle starts from a stopped state. The discharge port of the sub-hydraulic pump 43 is communicated with the oil chambers 28, 28a of the respective hydraulic actuators A through the passage 44, and the passage 44, the check valve 47, and the passage 17 are provided.
Through the discharge port of the sub-hydraulic pump 15. Passage 4
4 and the oil tank 26, a relief valve 46 and an electromagnetic on-off valve 45
Are connected in parallel.

When the vehicle is started, for example, when the operation switch of the instrument panel on the driver's seat is closed, the electromagnetic opening / closing valve 45 is closed and the electric motor 42 drives the auxiliary hydraulic pump 43. When the hydraulic pressure from the sub-hydraulic pump 43 reaches the set pressure of the relief valve 46, pressure oil is sent to the oil chambers 28, 28a of the actuators A, the hub clutches B are connected, and the hydraulic motors 41, 41a are driven by the hydraulic drive wheels. Rotationally connect to. The pressure oil from the sub hydraulic pump 43 flows to the sub hydraulic pump 15 via the check valve 47 and the passage 17, and the main hydraulic pump 12 is quickly started at the same time as the clutch 3 is connected.

On the other hand, when the clutch 3 is connected, the mechanical drive wheels are driven, and at the same time, the solenoid on-off valve 27a that was open while the clutch was shut off is closed, and the main hydraulic pump 12 and the hydraulic motors 41, 41a are fluidly connected. The main hydraulic pump 12
The pressure oil discharged from the high pressure passage 14 and the electromagnetic switching valve 2
5, the high-pressure passage 34, the hydraulic motors 41 and 41a, the low-pressure passage 33, the electromagnetic switching valve 25, and the low-pressure passage 13 are driven, the hydraulic motors 41 and 41a are respectively driven, and the hydraulic drive wheels are rotationally driven in the forward direction. .

When the operating switch is opened to stop the vehicle or the like, the electromagnetic opening / closing valve 45 is opened, the auxiliary hydraulic pump 43 is stopped, the hydraulic pressure is reduced to atmospheric pressure, and the hub clutch B is shut off by the force of the spring 58. That is, the transmission shaft 51 shown in FIG. 1 is pushed away from the hub 55 of the hydraulic drive wheel, and the hydraulic motor 41,
The rotational coupling between 41a and the hydraulic drive wheel is released.

In the embodiment shown in FIG. 5, the pressure oil of the sub-hydraulic pump 15 driven by the electric motor 42A is supplied to the hydraulic motor 4.
By supplying to the hydraulic circuits 1, 41a, hydraulic pressure is generated in the hydraulic circuits before the main hydraulic pump 12 rotates. When the actuating switch is closed, the solenoid on-off valve 27a
Is closed and the sub-hydraulic pump 15 is already driven by the electric motor 42A. Therefore, when the pressure oil in the hydraulic circuit exceeds the set pressure of the relief valve 19, the oil chambers 28, 28a of the actuators A are closed.
And each hub clutch B is connected. When the operation switch is opened, the electromagnetic opening / closing valve 27a is opened, the hydraulic pressure of the hydraulic circuit becomes atmospheric pressure, and each hub clutch B is shut off by the force of the spring 58.

In the embodiment shown in FIG. 6, the pressure oil of the auxiliary hydraulic pump 15 directly driven by the engine 2 is supplied to the hydraulic motor 41,
By supplying to the hydraulic circuit 41a, hydraulic pressure is generated in the hydraulic circuit before the main hydraulic pump 12 rotates. When the actuating switch is closed, the solenoid on-off valves 76, 27
Since a is closed and the sub-hydraulic pump 15 is already rotated by the engine 2, when the pressure oil in the hydraulic circuit exceeds the set pressure of the relief valve 19, it is supplied to the oil chambers 28, 28a of each actuator A and each hub clutch. B is connected. When the operation switch is opened, the electromagnetic opening / closing valve 76 is opened, the hydraulic pressure of the hydraulic circuit becomes atmospheric pressure, and the hub clutch B is shut off by the force of the spring 58.

In the embodiment shown in FIG. 7, pressure oil is supplied from the pressure accumulator 26A integrated with the oil tank 26 to the hydraulic circuits of the hydraulic motors 41, 41a, so that the hydraulic circuit is supplied to the hydraulic circuit before the main hydraulic pump 12 rotates. It generates hydraulic pressure. When the operation switch is closed, the electromagnetic switching valve 75 is switched to the position shown in the figure, and pressurized air is supplied from the air tank 74 to the air chamber of the pressure accumulator 26A. Oil in the oil chamber of the pressure accumulator 26A sealed by the flexible film 78 is pressurized and supplied to the oil chambers 28 and 28a of the actuators A, the hub clutch B is connected, and the hydraulic motors 41 and 41a are hydraulically operated. Rotatably coupled to the drive wheel. The air tank 74 is filled with pressurized air from an air compressor 73 driven by the engine 2.

When the operating switch is opened, the electromagnetic switching valve 75 is switched, the air pressure in the air chamber of the pressure accumulator 26A and the oil pressure in the oil chamber are reduced to atmospheric pressure, and the hub clutch B is shut off by the force of the spring 58. By setting the set hydraulic pressure of the pressure accumulator 26A lower than the set hydraulic pressure of the relief valve 19, the pressure accumulator 26A can always be kept at the maximum capacity without wasting the hydraulic pressure of the pressure accumulator 26A.

In the embodiment of FIG. 7, the auxiliary hydraulic pump 15
While the engine is stopped, pressure oil may be supplied from an independent pressure accumulator to the hydraulic circuit of the auxiliary hydraulic pump 15 and the hydraulic motors 41 and 41a.

In each of the above-described embodiments, when the traveling condition of the hydraulic drive mechanism is limited to starting or low drive torque traveling, the main hydraulic pump 12 may be of the constant discharge type.

[0034]

As described above, the present invention is such that the actuator that drives the hub clutch is connected by the discharge hydraulic pressure of the internal lubricating oil of the hydraulic motor that resists the force of the spring. Since the rotational connection between the hydraulic motor and the hydraulic drive wheels can be obtained before the main hydraulic pump rotates, the time delay at the time of starting is eliminated and the starting performance is greatly improved.

Since hydraulic pressure is applied to the hydraulic circuit of the hydraulic motor before starting the vehicle, it is possible to suppress the occurrence of the cavitation, for example, when the main hydraulic pump of the hydraulic drive mechanism is suddenly driven during sudden starting.

By limiting the operating range of the hydraulic motor depending on the vehicle speed and the like, the capacity of the main hydraulic pump and hydraulic motor of the hydraulic drive mechanism can be reduced, and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a side sectional view of a hub clutch mechanism for a hydraulic drive wheel of a vehicle according to the present invention.

FIG. 2 is an enlarged side sectional view showing an actuator of the hub clutch mechanism.

FIG. 3 is a hydraulic circuit diagram of a hub clutch control device for hydraulic drive wheels according to the present invention.

FIG. 4 is a hydraulic circuit diagram of a hub clutch control device for hydraulically driven wheels according to a second embodiment of the present invention.

FIG. 5 is a hydraulic circuit diagram of a hub clutch control device for hydraulically driven wheels according to a third embodiment of the present invention.

FIG. 6 is a hydraulic circuit diagram of a hub clutch control device for hydraulically driven wheels according to a fourth embodiment of the present invention.

FIG. 7 is a hydraulic circuit diagram of a hub clutch control device for hydraulically driven wheels according to a fifth embodiment of the present invention.

[Explanation of symbols]

A: Actuator B: Hub clutch 2: Engine
3: Clutch 4: Gear transmission 5: Intermediate shaft 6: Intermediate gear 7: Output shaft 8: Actuator 10: Output shaft 11: Power extraction mechanism 12: Main hydraulic pump 13: Low pressure passage 14: High pressure passage 15: Sub hydraulic pump 18:
Filter 19: Relief valve 23: Check valve 24: Relief valve 25: Electromagnetic switching valve 26: Oil tank 26A: Accumulator 2
7: Bypass passage 27a: Electromagnetic on-off valve 28: Oil chamber
28a: Oil chamber 29: Cylinder 29a: Cylinder 3
0: Piston 30a: Piston 35: Bypass passage 36: Electromagnetic directional control valve 37: Actuator 3
8: Rod 39: Piston 40: Cylinder 41:
Hydraulic motor 41a: Hydraulic motor 42, 42A: Electric motor 43: Sub hydraulic pump 44: Passage 45: Electromagnetic on-off valve
46: Relief valve 47: Check valve 51: Transmission shaft 53: Main shaft 53a: Spline shaft portion 55: Hub 55a: Dog tooth 56: Lid 57: Cylindrical body 57a: Spring seat 58,
58a: spring 59: dog tooth 63: nut 64, 64a: relief valve 66, 66a: check valve 71, 71a: check valve 72, 72a: check valve 73:
Air compressor 74: Air tank 75, 76: Electromagnetic on-off valve
78: Membrane

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaro Hamada, 489 Maibara, Mukawa-cho, Yufutsu-gun, Hokkaido Isuzu Motors Co., Ltd. Hokkaido Proving Ground (72) Hiromi Kato, 489 Maibara, Yugawa-gun, Hokkaido Inside the Suzuki Proving Ground

Claims (7)

[Claims] 1. A mechanical drive wheel driven by an engine via a gear transmission, a main hydraulic pump driven by the engine, and a pair of hydraulic motors driven by pressure oil from the main hydraulic pump. A hydraulic drive wheel driven by the hydraulic motor, an auxiliary hydraulic pump for compensating the hydraulic pressure of a hydraulic circuit connecting the main hydraulic pump and the hydraulic motor, and the hydraulic motor and the hydraulic drive wheel. A hub clutch for connecting / disconnecting rotation with the hub and an actuator for driving the hub clutch are provided, and the actuator is driven to the connection position by the discharge pressure of the internal lubricating oil of the hydraulic motor that resists the force of the spring. A hub clutch control device for a hydraulic drive wheel of a vehicle, characterized in that 2. The hub clutch comprises dog teeth provided on a tip portion of a transmission shaft and dog teeth provided on an inner peripheral surface of a hub of a hydraulic drive wheel, and the actuator is an end portion of a main shaft of the hydraulic motor. The hub clutch control device for a hydraulic drive wheel of a vehicle according to claim 1, further comprising an oil chamber formed between the main shaft and a base end portion of a transmission shaft spline-fitted to the main shaft. 3. The auxiliary hydraulic pump is driven by the same shaft as the main hydraulic pump, and while the auxiliary hydraulic pump is stopped, pressure oil is supplied from another hydraulic pump driven by an electric motor to the hydraulic circuit. The hub clutch control device for a hydraulic drive wheel of a vehicle according to claim 1, which is supplied to the hydraulic motor. 4. The hub clutch control for a hydraulic drive wheel of a vehicle according to claim 1, wherein the sub hydraulic pump is driven by an electric motor, and pressure oil is supplied from the sub hydraulic pump to the hydraulic circuit and the hydraulic motor. apparatus. 5. The hydraulic drive wheel for a vehicle according to claim 1, wherein the sub hydraulic pump is directly driven by the engine, and pressure oil is supplied from the sub hydraulic pump to the hydraulic circuit and the hydraulic motor. Hub clutch control device. 6. The sub-hydraulic pump is driven by the same shaft as the main hydraulic pump, and while the sub-hydraulic pump is stopped, pressure oil is supplied from a pressure accumulator connected to the hydraulic circuit to the hydraulic circuit. The hub clutch control device for a hydraulic drive wheel of a vehicle according to claim 1, which is supplied to the hydraulic motor. 7. The sub-hydraulic pump is driven by the same shaft as the main hydraulic pump, and while the sub-hydraulic pump is stopped, an air compressor directly driven by the engine to a sealed oil tank. The hub clutch control device for a hydraulic drive wheel of a vehicle according to claim 1, wherein pressurized air is supplied and pressure oil is supplied from the oil tank to the hydraulic circuit and the hydraulic motor.