JPH09123817A - Seat suspension - Google Patents

Abstract

PROBLEM TO BE SOLVED: To absorb impact at rising time after a driver's seat sinks in by arranging a cushion member which exhibits a suspension action by coming into contact with the driver's seat when the driver's seat sinks in by a specific quantity or more against energizing force of a tension spring. SOLUTION: A driver's seat 4 is supported above a cover plate 9 by a parallel link mechanism 10 having a seat suspension S, and a tension spring 11 is arranged to energize the parallel link mechanism 10 to the standing-up side along almost a diagonal line of its parallel link mechanism 10. A cushion member 12 is arranged so as to exhibit a suspension action by coming into contact with the driver's seat 4 when the driver's seat 4 sinks in by a specific quantity or more against energizing force of its tension spring 11. Therefore, impact at rising time after the driver's seat 4 sinks in can be absorbed.

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 Publication No. 52-86125, tension springs are installed on diagonal lines of a pair of front and rear parallel links.
A means for absorbing the vibration of the airframe by utilizing the extension of the tension spring, or, as shown in JP-A-6-219193, a compression spring for a cushion is provided between the operating seat and the airframe fixing part, It was a means to absorb the vibration of the airframe by utilizing the contraction of the spring.

[0003]

According to the former means,
As shown in FIG. 9, when the characteristic of spring extension is shown in a graph, the seat depression amount and the spring extension amount are substantially proportional until the operating seat sinks more than a certain amount, but the seat sinks more than a certain amount. And the amount of spring extension suddenly decreases. In other words, since the parallel link descends with the lower part as the fulcrum and the upper part draws an arc locus, the amount of displacement in the lateral direction becomes smaller than the amount of vertical displacement as it descends, and the extension of the tension spring suddenly decreases. Then, there is an inconvenience that the suspension action suddenly deteriorates. On the other hand, according to the latter means, as shown in FIG. 10, the spring load increases in proportion to the seat sinking amount, and the suspension function is satisfactorily exhibited, but the space ratio is increased. The spring stroke is too long. That is, in order to improve the cushion, a soft spring having a large contraction amount is used as compared with a hard spring having a small contraction amount, so that the stroke of the spring cannot be increased in proportion to the space. Therefore, the relationship between the load on the seat surface and the seat sinking amount cannot be freely set, and there is a disadvantage that the degree of freedom in design for realizing a comfortable ride is small.

An object of the present invention is to devise a structure of a seat suspension so that a good suspension action can be exhibited even in a small installation space.

[0005]

The present invention according to claim 1 is a seat suspension for a driver's seat, which is connected to a fixed portion on a machine body side through a parallel link mechanism,
A tension spring for urging the parallel link mechanism toward the upright side is provided substantially along the diagonal line of the parallel link mechanism, and when the operation seat sinks a certain amount or more against the urging force of the tension spring, it comes into contact with the operation seat. A cushion member that exerts a suspension function is provided. [Operation] As shown in FIG. 6, when the characteristic of spring extension is shown, the tension spring exerts a suspension function at the beginning with respect to the seat subsidence, and the suspension function of the tension spring due to the depression above a certain level. When it is lowered, the cushion member then exerts a suspension function. [Effect] As described above, the combination of the tension spring and the cushion member increases the repulsive force of the suspension in proportion to the seat sinking amount, so that an ideal suspension characteristic can be obtained. Moreover, the cushion member is long enough to support the suspension function of the tension spring, requires only a small installation space, and has a large degree of freedom in design to achieve a comfortable ride. It can also be applied to models with limited space.

According to a second aspect of the present invention, the cushion member is provided in the parallel link mechanism, and the cushion member is brought into contact with the driver's seat by a change in relative posture of the parallel link mechanism with respect to the driver's seat to exert a suspension action. It is a thing.

According to a third aspect of the present invention, the cushion member is provided on the lower surface of the operation seat or the upper surface of the machine body side fixing portion.

According to a fourth aspect of the present invention, when the operating seat returns to its original ascending position by the restoring force of the tension spring, the cushion comes into contact with the operating seat to exert a suspension action on the ascending side of the operating seat. Members are provided. [Operation] Since the repulsive force after the seat is sunk against the sway of the aircraft is large, it is a negative factor in terms of comfort, but a cushioning member for cushioning shock on the air bearing side of the seat is provided. It is possible to absorb the shock when it floats up after sinking. [Effect] As a result of the above configuration, the impact on the seat rising side due to the repulsive force of the seat suspension that alleviates the impact in the direction in which the driving seat is depressed can be mitigated, and the overall riding comfort is improved.

According to a fifth aspect of the present invention, a cushion member that exerts a suspension action on the ascending side of the driving seat is provided in the parallel link mechanism, and driving is performed by changing the relative attitude of the parallel link mechanism with respect to the driving seat. It comes into contact with the seat and exerts a suspension action on the rising side of the driving seat.

[0010]

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. 4, in this agricultural tractor, a diesel engine 2 is arranged in a hood 1 at the front of the fuselage, a driving seat 4 is provided above a mission case 3 at the rear of the fuselage, and an upper rear end of the mission case 3 is provided. Is equipped with a pair of left and right lift arms 5 and 5, and a hydraulic cylinder 6 for vertically swinging the lift arms 5 and 5 is disposed above the mission case 3, and the left and right rear wheel fenders 7 are provided above the mission case 3. , A cover plate 9 for connecting 7 is installed.

The operating seat 4 is supported above the cover plate 9 by a parallel link mechanism 10 having a seat suspension S. The parallel link mechanism 10 includes a pair of left and right front links 10A and a pair of left and right rear links 10B that are provided over the bracket 9a on the cover plate 9 side and the bracket 4a on the driver seat 4 side.
It is constituted by. The pair of left and right rear links 1
OB is composed of a U-shaped plate that is open upward by bending both left and right pieces of the plate upward. The seat suspension S includes a tension spring 11 and a cushion rubber 1 for cushioning the impact of the driving seat 4 in the sinking direction.
2 and the cushion rubber 13 for cushioning the impact of the driving seat 4 in the floating direction. The tension spring 11 extends substantially along the diagonal line of the parallel link mechanism 10 between the operation tool 14 rotatably mounted on the bracket 9a of the cover plate 9 as the machine side fixing portion and the horizontal axis 10b of the rear link 10B. The rotary operation tool 14 is constructed by being erected, and includes an operation knob 14a rotatably attached to a bracket 9a on the cover plate 9 side and a nut 14b provided with a U-shaped metal fitting for spring locking. The tension of the spring 11 can be adjusted by moving the nut 14b with the spring locking metal fitting in the front-rear direction as the operation knob 14a is rotated. The cushion rubber 12 that absorbs the impact of the driving seat 4 in the sinking direction is fixedly provided on the pedestal 10a provided on the rear link 10B, and when the driving seat 4 sinks a certain amount or more, the driving seat 4 Is brought into contact with the cushion rubber 12 to exert a suspension function. The cushion rubber 13 for cushioning the impact of the operating seat 4 in the floating direction is fixedly provided on the mounting seat 10c provided on the rear link 10B, and is configured to be vertically movable integrally with the rear link 10B. There is. When the driving seat 4 approaches the upper limit of the vertical swing range, the cushion rubber 13 changes due to a change in the relative posture of the rear link 10B with respect to the driving seat 4.
Is brought into contact with the lower surface of the driving seat 4a to exert the suspension function. Therefore, the cushion rubber 13 regulates the upper limit of the driving seat 4 due to the pulling action of the spring 11.

In this agricultural tractor, the engine 2
In order to control the rotation speed of the engine, as shown in FIG. 5, the governor 2A of the engine can be mechanically and electrically operated. That is, the speed adjusting lever 2a of the governor 2A
A balance-type link 15 is attached to the tip of the engine, a rod 16 which is linked to an accelerator lever (not shown) is connected to one end of the balance link 15, and the other end of the engine is used to detect the load applied to the vehicle body. The actuator 17 for controlling the number of revolutions of the engine is connected, and the accelerator is used to fix the number of revolutions desired by the operator, and the load on the vehicle body is detected to automatically control the number of revolutions of the engine. It has become.

[Other Embodiments] In the above embodiment, elastic rubber is illustrated as the cushion members 12 and 13, but compression springs may be used.

Further, in the above embodiment, the cushion rubber 12 for cushioning the impact of the driving seat 4 in the sinking direction is provided on the rear link 10B of the parallel link mechanism 10 so that the driving seat 4 sinks more than a certain amount. The suspension action is exerted by contacting the inner surface of the bracket 4a on the 4th side. However, as shown in FIG. 7, when the driving seat 4 is provided on the cover plate 9 side and sinks more than a certain amount, the driving seat 4 The suspension action may be exerted by contacting the side bracket 4a.

Further, in the above embodiment, the cushion rubber 1 for cushioning the shock of the driving seat 4 in the floating direction is provided.
3 is provided on the rear link 10B of the parallel link mechanism 10 so that the cushion rubber 13 is brought into contact with the lower surface of the driver seat 4 to exhibit the suspension function due to a change in the relative attitude of the rear link 10B with respect to the driver seat 4. As shown in FIG. 8, a cushion rubber 13 is provided on the cover plate 9 side so that the parallel link mechanism 10 abuts on the cushion rubber 13 and exerts a suspension function when the operating seat 4 rises above a certain level. Alternatively, the cushion rubber 12 for cushioning the impact of the driving seat 4 in the sinking direction may be provided on the driving seat 4 side.

Furthermore, in the above embodiment,
In order to adjust the tension of the tension spring 11, the tension spring 11 is installed along a substantially diagonal line of the parallel link mechanism 10, that is, the operation tool 14 rotatably mounted on the bracket 9a on the cover plate 9 side. Although it was installed over the horizontal axis 10b of the rear link 10B, when tension adjustment is not required, the tension spring 11 is installed over the horizontal axis of the front link 10A and the horizontal axis 10b of the rear link 10B. May be.

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the configuration shown in the attached drawings.

[Brief description of the 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 perspective view of a seat suspension.

FIG. 4 is an overall side view of the tractor.

FIG. 5 is a perspective view showing a linkage between a governor, an accelerator rod, and an actuator.

FIG. 6 is a graph of spring characteristics

FIG. 7 is a side view of the second embodiment.

FIG. 8 is a side view of the third embodiment.

FIG. 9 is a graph of spring characteristics of the first conventional example.

FIG. 10 is a graph of spring characteristics of a second conventional example.

[Explanation of symbols]

 9 Fixed part on airframe side 10 Parallel link mechanism 11 Extension spring 12 Cushion member 13 Cushion member

Claims (5)

[Claims] 1. A seat suspension for a driver's seat (4) connected to a fixed part (9) on the airframe side via a parallel link mechanism (10), the suspension being substantially along a diagonal line of the parallel link mechanism (10). A tension spring (11) for urging the parallel link mechanism (10) toward the upright side is provided, and when the operation seat (4) sinks more than a certain amount against the urging force of the tension spring (11), the operation seat ( 4) A seat suspension provided with a cushion member (12) that comes into contact with 4) and exerts a suspension action. 2. The cushion member (12) is provided on the parallel link mechanism (10), and the parallel link mechanism (1) is provided.
The seat suspension according to claim 1, wherein the seat suspension is brought into contact with the driving seat (4) to exhibit a suspension action due to a change in relative posture of the driving seat (4) with respect to the driving seat (4). 3. The seat suspension according to claim 1, wherein the cushion member (12) is provided on the lower surface of the driving seat (4) or the upper surface of the machine body side fixing portion (9). 4. When the driving seat (4) returns to its original raised position by the restoring force of the tension spring (11), the driving seat (4) contacts the driving seat (4) and the suspension action on the rising side of the driving seat (4). The seat suspension according to any one of claims 1 to 3, which is provided with a cushion member (13) that exhibits the above-mentioned effect. 5. The parallel link mechanism (10) is provided with a cushion member (13) that exerts a suspension action on the rising side of the operating seat (4), and the operating seat (4) of the parallel link mechanism (10). The seat suspension according to claim 4, wherein the seat suspension is brought into contact with the driving seat (4) due to a change in a relative attitude with respect to the vehicle to exert a suspension action on the rising side of the driving seat (4).