JP2008132856A - Seat suspension structure of operating machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To structure a seat suspension structure of an operating machine to have high durability while obtaining favorable seating comfort regardless of the size of a seating load, in which a driver's seat is supported vertically movably via a link mechanism above a seat support table, and lifted and energized by the elastic force of a suspension spring arranged between the driver's seat and the seat support stand having its shaft center set in a lateral posture. <P>SOLUTION: This seat suspension structure is provided with a cam member 21 displaced vertically along with the vertical movement of the driver's seat 7, and a cam follower 22 displaced in the shaft center direction of the suspension spring 24 along with the vertical displacement of this cam member 21. One end of the suspension spring 24 is supported in the cam follower 22, and is configured to be displaced in an elastic force increasing direction along with the downward movement of the driver's seat 7. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a seat suspension structure used for a working machine such as an agricultural tractor or a mower.

As a seat suspension structure of an agricultural tractor, for example, as disclosed in Patent Document 1, a driving mechanism is supported on a seat support base in a vertically movable manner via a parallel quadruple link mechanism, and a link mechanism The suspension spring is stretched across the swing link and the seat support, and the link mechanism is biased upward by the elasticity of the suspension spring. It is known that the cushion rubber is elastically deformed when it is largely moved downward to improve the suspension characteristics.
JP-A-9-123817

The above conventional structure uses a suspension spring and cushion rubber together to provide a comfortable seating comfort regardless of the driver's weight, but the cushion rubber exposed to the outside air is within a relatively short period of time. In the case where a driver with a large weight is used, it is often necessary to replace the cushion rubber within a short period of time.
Since the elastic characteristics of the cushion rubber vary considerably depending on the temperature, the suspension characteristics may vary depending on the time of use and the local temperature conditions.

  The present invention has been made paying attention to such points, and an object of the present invention is to provide a highly durable seat suspension structure capable of obtaining a suitable sitting comfort regardless of the magnitude of the seating load. It is said.

According to a first aspect of the present invention, there is provided a suspension spring disposed between the driving seat and the seat support base, wherein the driving seat is supported above the seat support base via a link mechanism so as to be movable up and down, and the axial center is in a lateral orientation. In the seat suspension structure of a work machine that lifts and urges the driving seat by elasticity,
A cam member that moves up and down as the operating seat moves up and down, and a cam follower that moves in the axial direction of the suspension spring as the cam member moves up and down, supports one end of the suspension spring on the cam follower, The suspension spring is configured such that one end of the suspension spring is displaced in the direction of increasing elasticity as the driving seat moves downward.

According to the above configuration, the elasticity of the suspension spring with respect to the height position of the operation seat can be set by the cam curve at the contact portion between the cam member and the cam follower. For example, by setting a characteristic that linearly changes the height of the driving seat and the seat lifting force, the variation in the seat lifting bias force is always constant regardless of the seating load. It is easy to stabilize the sitting comfort regardless of the height of the driving seat.
By configuring the cam member and the cam follower with a hard member such as a metal material, the desired suspension characteristics can be stably maintained over a long period of time, and the suspension characteristics hardly change depending on temperature conditions.

  Therefore, according to the first invention, the seat suspension structure capable of obtaining a suitable seating comfort regardless of the seating load can be configured with high durability.

According to a second invention, in the first invention,
The cam member is provided in a swing link constituting the link mechanism.

  According to the above configuration, the cam member provided in the swing link moves along an arc locus centering on the fulcrum of the swing link. Therefore, the cam member is displaced in the vertical direction as well as in the longitudinal direction of the link. The cam follower can be displaced in the axial direction of the suspension spring using the cam member's displacement in the longitudinal direction of the link and the cam action. When the seat moves down greatly, it becomes easy to obtain a desired large elasticity by sufficiently displacing the suspension spring in the direction of increasing the elasticity.

  FIG. 1 shows an agricultural tractor that is an example of a working machine having a seat suspension structure according to the present invention. This agricultural tractor has a four-wheel drive type tractor 3 having a front wheel 1 as a steering wheel and a rear wheel 2 as a main propulsion wheel. The PTO shaft 5 is provided, and an operation seat 7 is disposed between the left and right rear wheel fenders 6 in the rear portion of the tractor main unit 3.

  Between the left and right rear fenders 6, a support frame 8 having a sheet metal structure that covers the rear portion of the tractor main unit 3 is fixedly arranged, and a link is attached to the seat support base 9 that is bolted and fixed on the support frame 8. The operation seat 7 is supported via the mechanism 10 so as to be movable up and down.

  The link mechanism 10 includes a pair of left and right swing links 11 pivotally connected to a front portion of an extension portion 9a projecting rearward from the seat support base 9 so as to swing up and down around a fulcrum a, and a rear portion of the standing side 9a. The swing link 12 is pivotally connected so as to be swingable up and down around the fulcrum b, and the lift frame 13 is pivotally connected via the fulcrums c and d over the free ends of the swing links 11 and 12. Are pivotally connected in a parallel quadruple link shape. The elevating frame 13 is configured by bending a plate material downwardly in a U-shape when viewed from the front, and the movable base 14 attaches the slide rail mechanism 15 to the support frame portion 13 a connected and fixed to the left and right of the elevating frame 13. The driver's seat 7 is connected to the front end of the movable base 14 so as to be swingable around the fulcrum e.

  The left and right swing links 11, 12 are integrated by being bridged and connected by stays 11 a, 12 a, respectively, and the lifting frame 13 is moved up and down in parallel while maintaining a horizontal posture without tilting left and right. The left and right support frame portions 13a of the elevating frame 13 are bridged and connected by a stay 13b, and a telescopic damper 16 is installed between the stay 13b and the seat support base 9, so that the elevating frame 13 has an appropriate resistance to vertical movement. Is to be given.

  A cam member 21 is connected and fixed to the lower surface of the stay 11a in the front swing link 11, and a cam follower 22 that contacts the cam member 21 is connected to the bracket 9c connected to the front portion of the seat support base 9 in the front-rear direction. It is arranged to be slidable. The cam follower 22 is fixed to the left and right center of the support member 22a having a planar shape that is refracted from the plate material and configured to have a backward U shape, and is fixed to the left and right ends of the support member 22a and the rear portion of the sheet support base 9. A pair of left and right suspension springs 24 are stretched across the spring receiving member 23 with their axial centers facing sideways (substantially horizontal).

  The cam follower 22 is slid backward and biased by the elastic tension of the suspension spring 24, so that the link mechanism 10 is pushed upward and oscillated via the cam member 21, and the driving seat 7 is elastically lifted and biased. ing. The rear end portion of the front swing link 11 extends rearward from the fulcrum a, and the upper end of the link mechanism 10 is regulated by the extension portion 11a coming into contact with the upper surface of the seat support base 9, so that The maximum height position of the sheet 7 is set.

  When the driver is seated and a seating load is applied to the driver's seat 7, the link mechanism 10 swings downward, so that the cam member 21 provided in the front swing link 11 contacts and presses the cam follower 22 forward, Corresponding to the magnitude of the seating load, the cam follower 22 moves forward while stretching the suspension spring 24, and when the seating load and the spring force are balanced, the downward operation of the link mechanism 10 stops.

  The downward cam surface of the cam member 21 and the contact surface of the cam follower 22 facing the cam member 21 are each formed with a predetermined convex curved surface so that the vertical position of the lifting frame 13 and the front and rear position of the cam follower 22 have a desired relationship. Thus, the relationship between the height position of the operation seat 7 and the seat lifting urging force by the suspension spring 24, that is, the suspension characteristic is determined. As for the suspension characteristics, it is preferable that the seat lifting urging force by the suspension spring 24 varies linearly with respect to the height variation of the driving seat 7, and according to this, the height of the driving seat 7 regardless of the magnitude of the seating load. It is possible to stabilize the seating comfort regardless of the height of the driving seat 7 by always keeping the fluctuation of the seat lifting urging force with respect to the fluctuation constant.

  A stopper bolt 25 with an operation knob is attached to the bracket 9c provided continuously with the front portion of the seat support base 9. The stopper bolt 25 is opposed to the front surface of the cam follower 22, and prevents the cam follower 22 from moving forward at the rear end of the stopper bolt 25, thereby lowering the lower movement limit of the lifting frame 13, that is, the lower limit height of the operation seat 7. The lower limit height of the operation seat 7 can be adjusted by rotating the stopper bolt 25 and moving it forward and backward.

  A cushion rubber 27 is provided on the bracket 26 extending from the seat support 9 to the left and right, and is opposed to the support frame portion 13a of the elevating frame 13 from below. The cushion rubber 27 is disposed at a position where it comes into contact with the support frame portion 13a when the elevating frame 13 is moved downward to near the lower limit, so that the cam follower 22 is shockedly brought into contact with the stopper bolt 25. Yes.

[Other Examples]
(1) As shown in FIG. 7, the rotary damper 16 can be mounted on the fixed fulcrum b of the rear swing link 12 for implementation.
(2) When the spring receiving member 23 is configured to be adjustable in the front-rear position so that the reference elasticity of the suspension spring 24 can be adjusted, a wider range of seating loads can be handled.
(3) It is also possible to configure and implement such that the relationship between the height position of the operation seat 7 and the elasticity of the suspension spring 24, that is, the suspension characteristics can be changed and adjusted by adjusting or replacing the position of the cam member 21. It is.
(4) The link mechanism 10 may be configured in a pantograph manner to support the operation seat 7 so as to be movable in parallel up and down. In this case, the suspension spring 24 can also be incorporated so that the axis of the suspension spring 24 is in the horizontal direction.
(5) The cam member 21 may be attached to the lifting frame 13 for implementation.
(6) By forming a cam surface on the lower side of the front swing link 11, the front swing link 11 itself can be used as the cam member 21.
(7) A compression coil spring can be used as the suspension spring 24.
(8) It is also possible to provide a free-rolling roller at either one of the cam member 21 and the cam follower 22 so that the cam action can be performed smoothly.

Whole side view of agricultural tractor Side view showing seat suspension structure Longitudinal side view showing the seat suspension structure with no seating load (A) and the seating load (B) Plan view of seat suspension structure Front view of seat suspension structure Longitudinal front view of seat suspension structure Side view showing a seat suspension structure of another embodiment

Explanation of symbols

7 Operation seat 9 Seat support 10 Link mechanism 11 Swing link 21 Cam member 22 Cam follower 24 Suspension spring

Claims (2)

The driving seat is supported above the seat support base via a link mechanism so as to be movable up and down, and the driving seat is supported by the elasticity of the suspension spring arranged between the driving seat and the seat support base with the axis centered in the horizontal position. In the seat suspension structure of the working machine that is lifted and biased,
A cam member that moves up and down as the operating seat moves up and down, and a cam follower that moves in the axial direction of the suspension spring as the cam member moves up and down, supports one end of the suspension spring on the cam follower, A seat suspension structure for a working machine, wherein one end of a suspension spring is displaced in a direction of increasing elasticity as the operating seat moves downward.   The seat suspension structure for a working machine according to claim 1, wherein the cam member is provided in a swing link constituting the link mechanism.

Images