JPH06113627A - Wheel supporting structure of working vehicle - Google Patents

Abstract

PURPOSE:To provide a simple wheel supporting structure of working vehicle having shock-absorbing function on wheels by effectively utilizing a rise and fall hydraulic cylinder. CONSTITUTION:In a wheel supporting structure of working vehicle constituted in such a way that wheels 3 are held on a rocking end part of a wheel transmission case 2 pivoted vertically rockingly on a body, a hydraulic cylinder is linked and connected to an operation arm 2a attached to the wheel transmission case 2 in an integrated way and relative height of the wheels 3 from the body can be changed by expansion and contraction of the hydraulic cylinder, an air reservoir is formed in a hydraulic oil chamber for dropping the wheels in the hydraulic cylinder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention supports a wheel at a swinging end of a wheel transmission case which is pivotally supported on a machine body in a vertically swingable manner, and a hydraulic pressure is applied to an operating arm integrally provided on the wheel transmission case. The present invention relates to a wheel support structure for a work vehicle configured such that the operating portions of the cylinders are linked and linked, and the relative height of the wheels with respect to the body can be changed by the expansion and contraction operation of the hydraulic cylinder.

[0002]

2. Description of the Related Art In the wheel support structure for a work vehicle described above, a walk-behind rice transplanter as an example of the work vehicle has hitherto been disclosed, for example, in Japanese Utility Model Publication No. 63-129418.
There has been a configuration in which a buffer spring is interposed between the operating portion of the lifting hydraulic cylinder and the operating arm.

[0003]

The above conventional structure is constructed so that the relative height of the wheels can be controlled to be changed so that the height of the machine body against the field can be maintained at a predetermined height regardless of the unevenness of the tiller. , Even if the wheels are suddenly pushed up due to the unevenness of the ground as the aircraft travels,
The shock absorbing function of the spring prevents the occurrence of harmful effects such as damage to the interlocking operation mechanism for raising and lowering the wheels by absorbing shock. However, there is a drawback in that the buffer spring needs to be large and strong in order to elastically support the entire weight of the machine body, resulting in a high manufacturing cost. An object of the present invention is to provide a wheel support structure that can exhibit a shock absorbing function at low cost by reasonably improving the structure.

[0004]

A feature of the present invention is that in the wheel support structure for a working vehicle described at the beginning, an air pool is formed in the wheel lowering hydraulic fluid chamber of the hydraulic cylinder.

[0005]

Since there is an air pocket in the wheel lowering hydraulic chamber of the lifting hydraulic cylinder, even if the wheel is pushed up due to the unevenness of the field and a shock load is applied, for example, The accumulated air in the oil chamber on the pressure receiving side is compressed and exerts a cushioning function as an air suspension. It should be noted that the moment length is generally set so that the cylinder stroke becomes smaller with respect to the vertical movement amount of the wheel so that the hydraulic cylinder has a smaller operation stroke. Even so, a sufficient suspension function can be maintained.

[0006]

Therefore, by reasonably improving the hydraulic cylinder having a large hydraulic actuation force to control the height of the vehicle with respect to the field scene by changing the relative height of the wheels with respect to the vehicle, for example, Without using a suspension mechanism such as a large coil spring, it is possible to effectively prevent the harmful effects such as damage to the wheel lifting drive mechanism due to the shocking ground reaction force caused by the push-up of the wheel. A strong suspension mechanism for elastically supporting the weight is no longer necessary, and the structure can be simplified and the cost can be reduced. Incidentally, in the hydraulic drive system, air bubbles may be generated in the oil passage as the oil temperature rises, and as a result, an air pool may be formed. Since it is formed inside the room, the suspension function can always be exhibited even immediately after the start of work when the temperature of the hydraulic oil is low.

[0007]

Embodiments will be described below with reference to the drawings. Figure 1
Fig. 1 shows a walk-behind rice transplanter as an example of a work vehicle. In this rice transplanter, wheel transmission cases 2 are attached to the left and right sides of a transmission case 1 arranged at the front of the machine body so as to be vertically swingable around a horizontal axis X1, and the wheel transmission cases 2 are provided with swinging end portions. A pair of left and right traveling wheels 3 are supported, and an engine 5 is mounted on a frame 4 fixed to the mission case 1,
A planting claw 6, a seedling stand 7 and the like are provided at the rear of the machine body, a steering handle 8 is provided at the rear end, and a leveling float 9 is provided at the lower part of the machine body. In this rice transplanter, elevation control means for changing and controlling the relative heights of the left and right wheels 3 and 3 to maintain the planting depth substantially constant, and changing and controlling the relative heights of the left and right wheels 3 and 3 are used for the airframe. And a rolling control means for maintaining the tilted posture against the mud surface almost constant. That is, in FIG.
As shown in FIG. 3, a lift cylinder 10 is arranged in the lower part of the engine frame 4 along the front-rear direction, and a balance arm 11 capable of swinging the balance around a vertical axis Y1 is provided at the tip of a cylinder rod 10A of the lift cylinder 10. The left and right side portions of the balance arm 11 and the arms 2a, 2a fixedly erected from the base end portions of the left and right wheel transmission cases 2, 2 are interlockingly connected via connecting rods 12, 12, respectively. The left and right wheels 3 and 3 are simultaneously moved up and down relative to each other as the lift cylinder 10 is extended and contracted. Also, the cylinder rod 10A
A supporting member 13 is fixedly connected to the tip of the supporting member 1, and a cylinder rod 15a of a rolling cylinder 15 pivotally supported by one connecting rod 12 via a bracket 14 is attached to the supporting member 1.
3 is pivotally connected to the rolling cylinder 15, and the rolling cylinder 15 is expanded and contracted so that the balance arm 11 can be rotationally driven around the central vertical axis Y1 to change the relative heights of the left and right wheels 3 and 3. I am doing it. Then, as shown in FIG. 5, the rear part of the leveling float 9 is supported via a ball joint 16 so as to be vertically swingable around a rear lateral axis X2 and rolling around a front and rear axis X3, and at the same time, the machine body The front part is provided with a detection mechanism for detecting the vertical swing amount and the horizontal rolling amount based on the ground pressure fluctuation of the ground leveling float 9. In this detection mechanism, as shown in FIG. 4, a plate-shaped detection member 18 is integrally provided on a fixed bracket 17 on the front side of the leveling float 9, and the detection member 18 swings when the leveling float 9 rolls. The rocking member 19 and the hydraulic control valve 20 for the rolling cylinder 15 which are engaged with the pin in a long hole so as to be interlocked with each other are held in a neutral position in a substantially horizontal posture through the push / pull rod 21. And the lift cylinder hydraulic control valve 24 is linked through the link mechanism 23 with the push-pull rod 22 that slides up and down as the leveling float 9 moves up and down, and the leveling float 9 is neutralized at a predetermined height. It is constructed so that the state is maintained. In this way, the machine body is always maintained at a predetermined height and in a substantially horizontal posture.

As shown in FIG. 6, a hydraulic circuit for supplying hydraulic oil stored in the transmission case 1 to a rolling cylinder 15 or a lift cylinder 10 by a gear type hydraulic pump P driven by an engine 5. In addition, check valves 25 and 26 are respectively provided in the pair of pressure oil supply passages for the rolling cylinder 15, and when the rolling hydraulic control valve 20 is in the neutral state, The rolling cylinder 15 is slightly actuated due to the leak to effectively prevent the body from tilting left and right.

An air pool Q is formed in the wheel lowering hydraulic oil chamber R of the lift cylinder 10. That is,
As shown in FIG. 7, an air reservoir Q is formed at the end of the cylinder tube 10a in the wheel lowering hydraulic chamber in a state of being sealed by a bellows 27. Even if the hydraulic piston 10b reaches the stroke end, the bellows is arranged so as not to be directly pressed by the piston 10b. In this way, even when the wheels 3, 3 receive a shocking thrust force due to the unevenness of the tiller during work traveling in the field, the buffering function is exerted by the air compressing action in the air reservoir Q, and the rod is It is possible to prevent damage such as 12 in advance.

[Other embodiment] Bellows 2 in which gas is sealed
As shown in FIG. 8, 7 may be disposed on the wheel lowering operation oil chamber R side of the hydraulic piston 10b. Further, as shown in FIG. 9, the hydraulic oil supply / discharge port 28 on the wheel lowering hydraulic oil chamber R side of the lift cylinder 10 may be formed at a lateral position of the cylinder tube 10a. According to this structure, the bubbles contained in the hydraulic oil are located above the port 28 as the hydraulic oil is supplied and discharged in the mission case 1 due to the high speed rotation of the gears. The air is naturally accumulated in the space r in the small-diameter cylindrical portion and is not discharged outward even when the hydraulic piston 10b is moved, so that the air reservoir Q is always formed and maintained.

It should be noted that reference numerals are added to the claims to facilitate the comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

[Figure 1] Overall side view of rice transplanter

FIG. 2 is a plan view showing a lifting drive system.

FIG. 3 is a plan view showing a lifting drive mechanism.

FIG. 4 is a front view of the detection mechanism.

FIG. 5 is a perspective view of the leveling float support portion.

[Fig. 6] Hydraulic circuit diagram

FIG. 7 is a sectional view of a lift cylinder.

FIG. 8 is a sectional view of a lift cylinder according to another embodiment.

FIG. 9 is a sectional view of a lift cylinder according to another embodiment.

[Explanation of symbols]

 2 Wheel transmission case 2a Working arm 3 Wheel 10 Hydraulic cylinder R Wheel lowering working oil chamber Q Air pool

Claims (1)

[Claims] 1. An operation integrally supporting the wheel (3) while supporting a wheel (3) at a swinging end of a wheel transmission case (2) pivotally supported by an airframe so as to be vertically swingable. A wheel support structure for a working vehicle, wherein a hydraulic cylinder (10) is linked to an arm (2a) and the height of the wheel (3) relative to the body can be changed by expanding and contracting the hydraulic cylinder (10). A wheel support structure for a work vehicle in which an air pool (Q) is formed in a wheel lowering hydraulic chamber (R) of the hydraulic cylinder (10).