JPH08132902A - Hydraulic drive vehicle - Google Patents

Abstract

PURPOSE: To select and drive respective drive wheels of the front and rear wheels of a traveling vehicle according to the traveling condition. CONSTITUTION: Drive wheels are constituted of three wheels, a front wheel 20 as a steering wheel and rear wheels 21 and 21, the drive wheels are respectively provided with hydraulic motors 28, 29 and 29 and driven, the hydraulic motors 28, 29 and 29 are connected to a hydraulic pump Pin parallel and a switch valve C is provided in an oil supplying passage to each hydraulic motor for switching between a flow passage for driving only the rear wheels 21 and 21 and a flow passage for driving both front and rear wheels 20 and 21 and 21. Further, a flow dividing valve 3 for distributing flow to the front and rear hydraulic motors 28 and 29 and 29 and switch valves D and E for switching the front wheel between driving and idle running are provided in the flow passage for driving both of these front and rear wheels.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique in which a front wheel and a rear wheel of a traveling vehicle driven by a hydraulic motor can be selected according to the traveling situation.

[0002]

2. Description of the Related Art Conventionally, in a hydraulic traveling vehicle equipped with a hydraulic continuously variable transmission, 2WD (front wheel or rear wheel drive) and 4WD are used.
A configuration in which WD (all-wheel drive) can be switched is publicly known. In the case of this 2WD, the front wheels, which are the steered wheels, are made to idle, and only the rear wheels are driven so that high speed running is possible.
In the case of WD, the vehicle was traveling at a low speed so that the driver could reliably grip.

[0003]

However, in the case of a vehicle traveling on grass, if the vehicle turns on a minimum turning radius in a 4WD state, the front and rear wheels are fed with the same hydraulic pressure to the hydraulic motor. , Although turning at the same number of revolutions, because the distance from the center of turning is different, the number of revolutions of the wheels far from the center could not keep up and the turf was peeled off. So 4
When turning in WD, I had to avoid turning around and peeling off the grass to do inefficient work. In particular, in the case of a three-wheeled vehicle having only one steered wheel, the characteristic of the small turning performance cannot be fully utilized.

[0004]

The present invention uses the following means in order to solve the above problems. That is, in a traveling vehicle in which a hydraulic motor is arranged on each drive wheel for driving, each hydraulic motor is connected in parallel to a hydraulic pump, and only the rear wheels are driven in an oil passage to each hydraulic motor. A valve that switches between the flow passage and the flow passage that drives both the front and rear wheels is provided, and in the flow passage that drives both the front and rear wheels, a flow dividing valve that distributes to the front and rear hydraulic motors and a valve that switches between driving and idling the front wheel And the drive wheels are composed of one front wheel, which is a steered wheel, and three rear wheels.

[0005]

By using the above means, the present invention enables high speed two-wheel drive by switching the valve so that only the rear wheels are driven, and switching is performed to drive both the front and rear wheels. Low-speed three-wheel drive can be achieved by uniformly driving the flow-dividing valves, and in this state, the front wheels are switched to idle, whereby low-speed two-wheel drive is achieved and a three-wheeled vehicle with a small turning effect is obtained.

[0006]

The problems and configurations to be solved by the present invention are as described above, and the embodiments of the present invention shown in the accompanying drawings will be described below. FIG. 1 is a side view of a turf collector adopting the present invention, and FIG. 2 is a hydraulic circuit diagram of the present invention.

The overall structure of the turf collector T will be described with reference to FIG. The turf collector T is a three-wheel drive hydraulically driven vehicle. A front wheel 20 serving as a steered wheel is arranged below the front of the main frame 30, and rear wheels 21 and 21 are arranged below the main frame 30. The front wheel 20 has a hydraulic motor 28. , A hydraulic motor 29 for the rear wheels 21, 21
・ 29 is attached so that it can be driven. Also,
A front column 32 is erected on the front portion of the main frame 30, and a handle 33 is arranged on the front column 32. Further, a driver's seat 31 is installed behind the front column 32, an engine 44 is arranged on the side of the driver's seat 31, and support frames 34, 34 are erected from the main frame 30 on both side ends of the driver's seat 31. are doing.

A grass collection tank 35 is arranged behind the driver's seat 31, and an opening / closing lid 36 is provided at the rear of the grass collection tank 35.
The opening / closing lid 36 is rotatably supported about the upper part thereof. Link fixing plates 37, 37 are fixed to both sides of the rear lower part of the grass collecting tank 35, and the supporting frame 3
An upper link 38 and a lower link 39 are pivotally supported between the upper portions of the parts 4 and 34 and the link fixing plates 37 to form a substantially parallel link. Dump cylinders 40, 40 are pivotally connected between the middle portion of the lower link 39 and the main frame 30. Further, on the rear part of the grass collection tank 35 and the opening / closing lid 3
An opening / closing cylinder 41 is provided between the upper part of 6 and the dump cylinders 40, 40. When the dump cylinders 40, 40 are extended, the rear part of the grass collection tank 35 is lifted so as to incline downward. The opening / closing lid 36 is opened so that the collected items inside can be discharged.

A grounding work machine 87 is arranged below the front part of the grass collection tank 35. The grounding work machine 87 has front wheels 20.
A rotary shaft 23 is horizontally laid between the rear wheel 21 and the rear wheel 21, and a hydraulic motor 43 is arranged at one end of the rotary shaft 23 so that the rotary shaft 23 can be driven to rotate. A brush 22 is formed in the front part of the grass 22. The brush 22 is covered with a shooter 24, and its upper end is inserted into the front inside of the grass collecting tank 35. The brush 22 is rotated to scrape grass clippings and fallen leaves into the grass collection tank 35.

Working machine lifting cylinders 42, 42 are interposed between the front surface of the shooter 24 and the middle portions of the support frames 34, 34, and the ground working machine 87 can be lifted and lowered by the working machine lifting cylinders 42, 42. I am trying. A damper 25 is connected to a rear surface of the shooter 24, and a rear portion of the damper 25 is pivotally supported by a pivotal connection portion 26 of a main frame 30 so as to be vertically rotatable and can be horizontally swung by the damper 25. There is.
In addition, the grounding wheels 27, 27 are provided on both sides of the shooter 24.
Is installed so that the installation height can be adjusted.

Then, the hydraulic pump P and the auxiliary pump P'in the pump unit N are driven by the output of the engine 44 arranged on the side of the driver's seat 31. The hydraulic pump P is composed of a variable piston pump, and the pressure oil is supplied to each hydraulic motor 28 via a hydraulic circuit K of the present invention described later.
・ It is sent to 29 ・ 29. Also, the cylinder 40
The pressure oil from the auxiliary pump P ′ is sent to the 41 and 42 and the brush drive motor 43 via the hydraulic circuit L.

The hydraulic circuit K and the hydraulic circuit L will be described with reference to FIG. In the hydraulic circuit L, the pressure oil from the auxiliary pump P ′ is sent to the working machine hydraulic unit M via the oil passage 50, and in the working machine hydraulic control unit M, the oil passage 51 passes through the switching valve F. Brush drive motor 43 can be driven, the dump cylinders 40 and 40 can be expanded and contracted from the oil passage 52 through the switching valve G, and the work machine lifting cylinders 42 and 42 can be expanded and contracted from the oil passage 53 through the switching valve H. age,
Hopper opening / closing cylinder 4 from the oil passage 54 via the switching valve I
1 can be expanded and contracted. 73 is a relief valve. Reference numeral 65 is a return oil passage.

The hydraulic circuit K of the present invention will be described. The oil passage 1 and the oil passage 15 are connected to the hydraulic pump P, and the oil passages 1 and 15 are connected to the hydraulic motors 28, 29 and 29 through the switching valve and the diversion valve to form a closed circuit. , HST type transmission is formed. Pressure oil can be supplied to the closed circuit from the return oil passage 65 through check valves 78 and 79. Further, the relief valves 70 and 71 adjust the hydraulic pressure during closing. When the oil is sent to the oil passage 1, the hydraulic motor 28
・ 29 ・ 29 are driven forward to drive the front wheel 20 ・ rear wheel 21.2
1 can be driven forward, and conversely, when oil is fed to the oil passage 15, it is rotated in the reverse direction and rotated in the backward direction.

The oil passage 1 is connected to a low speed oil passage 2 and a high speed oil passage 7 via a switching valve C, and a diversion valve 3 is connected to the low speed oil passage 2, one of which is a front wheel side oil. The passage 4 and the other one are connected to the rear wheel side oil passage 5, the front wheel side oil passage 4 is connected to the switching valve D and the switching valve E, and the oil passage 11 is connected to the secondary side of the switching valve E.
12 is connected to a hydraulic motor 28, and another primary side of the switching valve E is connected to an oil passage 13.
3 is connected to the oil passage 15. The secondary oil passage 14 of the switching valve D is connected to the oil passage 13. Also,
The high speed oil passage 7 is connected to the rear wheel side oil passage 5, and the rear wheel side oil passage 5 is connected to the hydraulic motors 29, 29 via the oil passages 8, 8.
The other output side of the hydraulic motors 29, 29 is connected to the oil passage 15. Check valves 16 and 16 'are provided in the oil passages 11 and 12 of the hydraulic motor 20, respectively.
It is connected to the tank 6 via.

The switching valve C is an electromagnetic pilot type 4-port 2-position switching valve. One of the primary side is connected to the oil passage 1 and the other is blocked, and the secondary side is a low speed oil passage 2 and a high speed. It is connected to the oil passage 7. The switching valve D is a 4-port, 2-position switching electromagnetic valve. One of the primary side is blocked by the front wheel side oil passage 4, the other is blocked, and one of the secondary sides is blocked by the oil passage 1.
4 and the other is blocked. The switching valve E is an electromagnetic pilot type 4-port 2-position switching valve, the primary side is connected to the front wheel side oil passage 4 and the oil passage 13, and the secondary side is connected to the oil passages 11 and 12.

In such a structure, the rear wheel 21 is operated at a low speed.
Explaining the oil feeding circuit in the two-wheel drive traveling of 21, first, the switching valves C, D and E are turned off. The pressure oil from the hydraulic pump P is sent to the flow dividing valve 3 via the oil passage 1, the switching valve C, and the low speed oil passage 2. In the shunt valve 3, the oil is diverted to the front wheel side oil passage 4 and the rear wheel side oil passage 5 in a ratio of 1: 2, and the pressure oil from the front wheel side oil passage 4 is blocked by the switching valve E. 20 is not driven, the switching valve D is brought into a communicating state and returned to the oil passage 15, and the rear wheel side oil passage 5
Only the hydraulic motors 29, 29 are driven by the pressure oil from, and low speed two-wheel drive is performed.

In the low speed two-wheel running state, the switching valve E is blocked and the oil passages 11 and 12 on the secondary side are in communication with each other, so that the front wheels 20 run idle. Reference numeral 28 is rotated by the drive shaft of the front wheels 20 and functions as a hydraulic pump. For this reason, the hydraulic oil is the oil passage 1
1 is circulated between the oil passage 12 and the oil passage 12, and if a shortage of hydraulic oil occurs in the closed circuit, the check valve 16, 16 'can suck the insufficient hydraulic oil from the tank 6.

During low speed three-wheel drive, the switching valve C is turned off, and the switching valves D and E are turned on. The pressure oil from the hydraulic pump P is sent to the flow dividing valve 3 via the oil passage 1, the switching valve C, and the low speed oil passage 2. In the diversion valve 3, the diversion oil is sent 1: 2 to the front wheel side oil passage 4 and the rear wheel side oil passage 5, and the pressure oil from the front wheel side oil passage 4 is blocked by the switching valve D and the switching valve E. Are switched and communicate with the oil passage 12, so that the hydraulic motor 28 is driven and the front wheels 20 are rotationally driven. On the other hand, the hydraulic motors 29, 29 are driven by the pressure oil from the rear wheel side oil passage 5, and low speed three-wheel drive is performed.

In the high speed two-wheel drive state,
The switching valves C and D are turned on, and the switching valve E is turned off.
Therefore, the pressure oil from the hydraulic pump P is transferred from the oil passage 1 to the switching valve C.
Oil is sent to the high-speed oil passage 7 via the, and flows into the rear wheel side oil passage 5 and flows from the flow dividing valve 3 to the front wheel side oil passage 4, but since the switching valve D is ON and the switching valve E is OFF, both are Blocked
The entire amount of pressure oil is sent only to the hydraulic motors 29, 29,
The rear wheels 21, 21 will be driven at high speed.

[0020]

Since the present invention is constructed as described above,
The following effects are obtained. That is, by switching the valve so that only the rear wheels are driven, high-speed two-wheel drive can be performed, and high-speed traveling becomes possible. Further, by switching to drive both the front and rear wheels and driving them evenly by the shunt valve, low-speed three-wheel drive can be achieved, and stable traveling on a slippery road surface is possible. Then, in this state, by switching the front wheels to idle, low-speed two-wheel drive,
This makes it possible to make a sharp turn at a low speed, and when traveling on grass or a field at this time, the road surface is not damaged due to the difference in rotational speed.

[Brief description of drawings]

FIG. 1 is a side view of a turf collector adopting the present invention.

FIG. 2 is a hydraulic circuit diagram of the present invention.

[Explanation of symbols]

 P hydraulic pump K / L hydraulic circuit 3 shunt valve 20 front wheel 21 rear wheel 28/29 hydraulic motor C / D / E switching valve

Claims (2)

[Claims] 1. A traveling vehicle for driving by arranging hydraulic motors on respective drive wheels, wherein the respective hydraulic motors are connected in parallel to a hydraulic pump, and a rear wheel is provided in an oil passage to the respective hydraulic motors. A valve that switches between a flow path that drives only the front and rear wheels and a flow path that drives both the front and rear wheels is provided, and a flow dividing valve that distributes both front and rear wheels to the front and rear hydraulic motors and a drive and idle rotation of the front wheels A hydraulically driven vehicle having a switching valve. 2. A hydraulically driven vehicle characterized in that the drive wheels according to claim 1 are composed of one front wheel, which is a steered wheel, and three rear wheels.