JPH09290672A - Seat suspension - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve vibration damping effect by providing a tension spring to energize a parallel link mechanism to an erection side and a fluid type damper free to extend and contract to give resistance to falling of the parallel link mechanism between a driver's seat and a fixed part of a body side. SOLUTION: A seat suspension S provided on a rear part of a machine body for agriculture is constituted of a parallel link mechanism 13, a tension spring 16, a cushion rubber 17 and a fluid type gas damper 18. This parallel link mechanism 13 is constituted of a pair of left and right front part link 13A and rear part link 13B, and the tension spring 16 is arranged along a diagonal line of the parallel link mechanism 13. Additionally, the cushion rubber 17 is devised so that when the driver's seat 9 sinks more than specified, a back surface of a rail support base 15 makes contact with the cushion rubber 17 and a suspension function is displayed, and the damper 18 is devised to give resistance to falling of the parallel link mechanism 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seat suspension for a work vehicle such as a tractor and a lawn mower.

[0002]

2. Description of the Related Art In a conventional seat suspension, as shown in Japanese Utility Model Laid-Open No. 52-86125, tension springs are installed along diagonal lines of a pair of front and rear parallel links to utilize the tension force of the tension springs. To reduce the impact force due to the vibration of the machine body, or as shown in Japanese Patent Laid-Open No. 6-219193, one of the front links or the rear links in the pair of front and rear parallel links is fixed to the machine body. There is a means for relaxing a shock force caused by vibration of the machine body by using a compression force of the spring by interposing a compression spring between the section and the section.

[0003]

In any of the above-mentioned conventional structures, the spring that absorbs the impact force of the driving seat acts as a repulsive force to push up the driving seat when absorbing the impact force. Then, in relaxing the impact force of the driving seat, the impact force is relaxed by using a soft spring having a small spring constant rather than using a hard spring having a large spring constant. Was large and the vibration damping effect was low, and there was room for improvement. An object of the present invention is to obtain a compact seat suspension structure having a high vibration damping effect by devising the structure of the seat suspension.

[0004]

According to a first aspect of the present invention, there is provided a tension spring for urging the parallel link mechanism toward a standing side, and the parallel link between a driving seat and a fixed portion on the body side. An expandable and contractible fluid damper that provides resistance to the collapse of the mechanism is provided. [Operation] With respect to the sinking of the driving seat due to the vibration of the machine body, the tensile force of the tension spring and the resistance force of the damper act to prevent the vibration of the machine body from being transmitted to the operator. Then, the damper acts as a resistance force against the rise of the driving seat due to the repulsive force of the spring, which suppresses the rising of the driving seat and reduces the amplitude of the driving seat. Further, since the tension spring is used as the buffer spring, the spring can be arranged in a small space as compared with the case of using the compression spring, and the load on the seat surface and the sinking amount of the seat can be reduced. Easy to set relationships. In other words, when using a compression spring, it is necessary to make a space for arranging the compressed spring itself in the space for arranging the spring, which reduces the contraction stroke of the spring, and therefore the cushion is When using a soft spring with a large amount of contraction to improve the cushion, the stroke for improving the cushion cannot be set large, and it is difficult to freely set the relationship between the load on the seat surface and the seat depression amount. Become. [Effect] As described above, since the impact force of the driving seat is alleviated by using the tension spring and the damper together, a soft spring with a small spring constant is used to improve cushioning and reduce the amplitude of the driving seat. The vibration damping effect can be enhanced. Moreover, since the tension spring is used as the cushioning spring, the cushioning device can be provided in a smaller space as compared with the case where the compression spring is used. Easy to set relationships.

According to a second aspect of the present invention, the tension spring and the damper are arranged so as to intersect each other in a side view. [Operation] The tension spring and the damper can be compactly arranged in the lower part of the driving seat by occupying a small space in the front and rear. [Effect] As a result of the above configuration, the shock absorber can be arranged compactly in the lower portion of the driving seat by shortening the front-rear length.

According to the third aspect of the present invention, the tension spring and the damper are arranged side by side within the lateral width of the pair of left and right front links and the pair of left and right rear links in the parallel link mechanism in a plan view. [Operation] The tension spring and the damper can be compactly arranged in the lower portion of the driver's seat by occupying a small space on the left and right. [Effect] As a result of the above configuration, the lateral width occupied by the shock absorber is narrowed in the lower part of the operating seat to make it compact in comparison with the case where the tension spring and the damper are separately arranged on the left and right lateral outside of the parallel link mechanism. Can be installed.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to an agricultural tractor. As shown in FIG. 7, in this agricultural tractor, an engine 4 is installed in a hood 3 at the front of the machine equipped with front and rear wheels 1 and 2, and a steering handle 6 and a PTO speed change lever 7 are provided in a control box 5. Provided,
An operation seat 9 is arranged above the mission case 8 at the rear of the machine body, and a pair of left and right lift arms 10 and 10 are provided at the rear of the mission case 8.

The driving seat 9 is provided above a body cover 12 in which a pair of left and right rear wheel fenders 11 and a cover portion covering the upper portion of the mission case 8 are integrally formed.
It is supported via a seat suspension S.

The seat suspension S includes a parallel link mechanism 13, a tension spring 16 for cushioning the impact of the driving seat 9 in the sinking direction, and a cushion rubber 1.
7 and a gas damper 18 as a fluid damper.

The parallel link mechanism 13 is a front surface which supports an inverted U-shaped front bracket 14 as a body fixing portion fixed to the upper surface of the body cover 12 and a frame 9A of the driving seat 9 so as to be slidable back and forth. It is composed of a pair of left and right front links 13A and a pair of left and right rear links 13B that are provided so as to extend across an inverted U-shaped rail support 15.

The tension spring 16 is arranged substantially along the diagonal line of the parallel link mechanism 13 in a side view, and has a rotary operation tool 19 rotatably attached to the front wall of the front bracket 14 and a rear portion. It is installed across a horizontal shaft 20 that connects the link 13B and the rail support 15. The rotation operation tool 19 includes a knob bolt 19a rotatably attached to the front wall of the front bracket 14,
It is composed of a nut 19b provided with a U-shaped metal fitting for spring locking, and the nut 19b with spring locking metal fitting is moved in the front-rear direction in accordance with the rotation operation of the knob bolt 19a, so that the tension of the spring 16 is increased. It can be adjusted.

The cushion rubber 17 is fixed to the plate 13b connecting the lower surfaces of the left and right rear links 13B and 13B and the upper surfaces of the left and right rear links 13B and 13B, respectively. Pedestal 13c,
It is fixedly connected to 13c, and when the driving seat 9 sinks more than a certain amount, the back surface of the rail support 15 comes into contact with the cushion rubber 17 to exert a suspension function.

The damper 18 is laid across the front portion of the rail support 15 and the rear bracket 21 of the body cover 12, and is in a state of intersecting the tension spring 16 in a side view and in a plan view. The tension springs 16 are arranged side by side in the lateral width of the pair of left and right front links 13A, 13A and the pair of left and right rear links 13B, 13B. The rear bracket 21 is provided with two pin holes 21a for changing the mounting position of the damper 18, and the stroke of the damper 18 is adjustable.

The damper 18 is a piston rod 18a.
Is a gas spring with a free piston that can be used regardless of the mounting posture of the piston rod 18a.

As shown in FIGS. 4 to 6, the PTO gear shift lever 7 has a guide groove 2 formed in the control box 5.
2 is configured so that the gears can be operated in four forward rotations and one reverse rotation. The PTO speed change structure will be described. In the transmission case a, high and low speed shift shafts 23, 24 for forward rotation and a shift shaft 25 for reverse rotation are arranged along the front-rear direction. Supporting member b on top of transmission case a
Further, a shift rod 26 including a shift arm 26A for selectively operating the three shift shafts 23, 24, 25 is slidably supported along the lateral direction of the machine body and rotatable about the rod axis. An operation arm 27a for slidingly operating the shift rod 26 on the support member b.
Is provided rotatably about a vertical axis Y, and the shift lever 7 is pivotally connected to the upper part of the vertical axis 27 so as to be vertically swingable about a horizontal axis X. It is provided so as to project rearward from the control box 5. The shift rod 26 is configured to be capable of holding its position at each selected position by a ball detent mechanism 28. Then, a rod 29 whose length can be adjusted is laid across the arm portion 26a fixed to the shift rod 26 and the speed change lever 7, and the shift shaft 23, 24 or 25 is operated by vertically swinging the speed change lever 7. Is configured to be slidable in the front-back direction. A switch 31 is attached to a vertical pipe 30 which rotatably supports the vertical axis 27 by providing a bracket on the upper portion thereof. The switch 31 is a normally-open limit switch connected to a starting circuit of an engine, and is turned on by a protrusion at a lower end of the speed change lever 7 when the speed change lever 7 is in neutral.
The safety is designed so that the engine can be started only when the O transmission lever 7 is in neutral.

[Other Embodiment] In the above embodiment, the gas spring with the free piston is described as the damper, but the damper may not be provided with the free piston. Further, the damper may be an air damper.

Further, in the above embodiment, the seat suspension of the tractor has been exemplified, but the seat suspension of a riding lawn mower or a combine may be used.

In the above-mentioned embodiment, the cushion rubber is provided as an example, but the cushion rubber may be omitted.

[Brief description of drawings]

FIG. 1 is a side view showing a working state of a seat suspension.

FIG. 2 is a plan view showing an arrangement state of a seat suspension.

FIG. 3 is a longitudinal sectional front view of the same.

FIG. 4 is a vertical sectional side view showing a mounting state of a PTO gear shift lever.

FIG. 5 is a schematic view of a guide groove.

FIG. 6 is a cross-sectional view showing a mounted state of a shift rod.

FIG. 7 is an overall side view of the tractor.

[Explanation of symbols]

 9 Driving seat 13 Parallel link mechanism 13A Front link 13B Rear link 14 Body side fixed part 16 Tension spring 18 Damper

Claims (3)

[Claims] 1. A seat suspension for a driver's seat, which is connected to a fixing part on the machine side via a parallel link mechanism, wherein the seat suspension is provided between the driver's seat and the fixing part on the machine side.
A seat suspension provided with a tension spring for urging the parallel link mechanism to the upright side, and an expandable and contractible fluid damper for giving resistance to the parallel link mechanism falling. 2. The tension spring and the damper are arranged so as to intersect each other in a side view.
Seat suspension described in. 3. The tension spring and the damper are arranged side by side within a lateral width of a pair of left and right front links and a pair of left and right rear links in the parallel link mechanism in a plan view. Seat suspension as described.