JPH05170007A - Speed change operation structure for working car - Google Patents

Abstract

PURPOSE:To provide a simple speed change operation structure for a working car which enables reliably positioning of a non-stage transmission at a neutral position thereof, the non-stage transmission being able to be frictionally retained at a given speed change position. CONSTITUTION:A continuously variable transmission 3 is provided in a travel drive system for a car body, the transmission 3 being made to have a free speed-change operation by rocking operation of a manually operable lever 10. A frictional retention mechanism A is also provided which is intended to frictionally retain the manually operable lever 10 at a given speed change operation position. In this speed change operation structure for A working car, the frictional retention mechanism A is so constructed as to frictionally retain a rocking boss section 13 of the manually operable lever 10 fitted over a support shaft for relative rocking movement, through pressing and urging of the rocking boss section 13 by a spring against and toward a support- shaft bracket 19. At a sliding contact portion between the rocking boss section 13 and the support-shaft bracket 19 and at a neutral speed change position, the rocking boss section 13 is formed with a forwardly tapered engaging projection 28 for being entered and engaged, for positioning, into and with a depthwise tapered engaging recess 27 formed in the support-shaft bracket 19.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a continuously variable transmission installed in a traveling drive system of an airframe, and the continuously variable transmission is configured to be capable of shifting by manipulating an operating lever.
The present invention relates to a gear shift operation structure for a work vehicle provided with a friction holding mechanism that frictionally holds an artificial operation lever at an arbitrary gear shift operation position.

[0002]

2. Description of the Related Art In the above-described gear shift operation structure for a work vehicle, conventionally, a neutral biasing mechanism for biasing the gear shift operation shaft of a hydrostatic continuously variable transmission to a gear shift neutral position is integrally rotated with the gear shift operation shaft. A cam is formed on an operation arm that is freely clamped and fixed, and a cam roller pressed against the cam is used to urge the gear to return to a gear shift neutral position (for example, a mechanism for fixing the gear shift position at an arbitrary position). Japanese Patent Application Laid-Open No. 2-10283 discloses an electric actuator driven system.
No. 2 publication].

[0003]

However, since the neutral urging mechanism in the above-mentioned conventional structure requires a large neutral restoring force to directly hold the shift operation shaft at the neutral shift position, the size of the device becomes large. There was a drawback that the structure became complicated. Further, recently, in order to improve the driving environment, not only the engine vibration-proof structure but also the hydrostatic stepless transmission is supported by vibration-proof to the machine body frame. If the hydrostatic continuously variable transmission is configured to support vibration isolation, vibration may be transmitted through the operation linkage mechanism between the gear shift operation shaft and the operation lever.Therefore, install a vibration isolation member in the middle of the linkage. In that case, since the gear shift operation shaft that works most effectively has a neutral biasing mechanism that requires precision, if it is configured to be provided at other locations, there is a drawback that the vibration damping function cannot be sufficiently exhibited. The present invention aims to eliminate the above-mentioned problems.

[0004]

According to the characteristic construction of the present invention, in the gear shift operation structure of the working vehicle described at the beginning, the rotation boss of the artificial operation lever fitted on the support shaft so as to be rotatable relative thereto. The friction holding mechanism is configured to press and urge the shaft bracket against the support shaft bracket by a spring to hold the friction, and the support shaft is provided at the gear shift neutral position at the sliding contact portion between the rotation boss portion and the support shaft bracket. A point is that a tapered tapered engagement projection that enters into and engages with the inner concave tapered engagement recess formed on the bracket is formed on the rotary boss portion.

[0005]

By providing the friction holding mechanism for holding the position at the arbitrary shift position near the rotation boss of the operation lever, the lever action of the operation lever causes a large friction to the operation linkage with the continuously variable transmission. While exerting power,
The lever can be lightly operated against the frictional force, and at the gear shift neutral position, the engaging concave portion and the engaging projection are fitted and engaged with each other to ensure reliable positioning in the gear shift neutral state. Be seen. Moreover, the engagement between the engagement recess and the engagement projection is performed by effectively utilizing the pressing biasing force of the friction holding mechanism. Further, since the engaging concave portion and the engaging protruding portion are configured to enter and engage with each other in a tapered shape, when the operation lever is operated to shift from this neutral position, the lever action and the taper action as described above are performed. It is possible to operate lightly due to the riding guide action on the surface.

[0006]

Therefore, the mechanism for holding the gear shift operation position at an arbitrary position is rationally constructed, and the improvement by simply adding the simple engagement mechanism does not reduce the operability and reduces the operability. It has become possible to obtain, with a simple configuration, a device that can reliably perform positioning in the neutral state of the gear transmission.

[0007]

Embodiments will be described below with reference to the drawings. Figure 7
Shows an agricultural tractor. In this agricultural tractor, an engine 2 is mounted in a hood 1 at the front of the machine body, and the power of the engine 2 is transmitted to front and rear wheels 5, 6 via a hydrostatic continuously variable transmission 3 and a transmission case 4. The hydrostatic stepless transmission 3 is configured to operate by a gear shift lever 10 projecting upward from a rear wheel fender 9 located on the left side of the driver's seat 8 in the body control unit 7. It is configured to do.

The gear shift operation structure will be described in detail below. As shown in FIGS. 1 and 2, a cylinder shaft 12 is externally fitted to a support shaft 11 fixed by screws in a state of protruding from the upper part of the transmission case 4 toward the lateral outside, and the transmission lever 10 is attached to the cylinder shaft 12. The rotating boss portion 13 is fitted and supported so as to be relatively rotatable. The free end side of the cylinder shaft 12 is also supported and fixed by a support shaft bracket 19 bolted to the transmission case 4 at the other two positions. The operation arm 14 formed integrally with the pivot boss portion 13 and the relay rotation arm 15
Are linked together via a push-pull rod 16, and a rotary shaft 17 that rotates integrally with the relay rotary arm 15 and a gear shift operation shaft 3a of the hydrostatic continuously variable transmission 3 are linked together by a link mechanism 18
The gear shaft 10 of the shift lever 10
The shift operation can be performed by the swinging operation around the axis. The rotating shaft 17 is rotatably supported by a pivot boss member 20 fixed to the upper part of the transmission case 4, and is interlockingly linked to the shift operation shaft 3a located on the opposite side of the machine body by penetrating in the machine body lateral direction. I am doing it. Further, the gear shift operation system is provided with a friction holding mechanism A which can hold the friction at an arbitrary operation position of the gear shift lever 10 and maintain the traveling speed of the machine body at that time even if the hand is released from the lever. That is, as shown in FIG. 3, the multi-plate friction mechanism 22 is slidably fitted onto the cylindrical shaft 12 to which the rotary boss 13 is fitted, and is pushed by the coil spring 24 via the sleeve 23. is there. The multi-plate friction mechanism 22 has a plurality of fixed friction plates 25 fixed in position with respect to the mission case 4 and a plurality of movable friction plates 26 that are integrally rotatable with the speed change lever 10 and are alternately arranged. Configured. Therefore, the pressing force of the coil spring 24 presses the multi-plate friction mechanism 22 received and supported by the support shaft bracket 19 to frictionally hold the speed change lever 10, and the position can be fixed at an arbitrary speed change position. Then, at the gear shift neutral position, the sliding boss portion 13 and the support shaft bracket 19 come into engagement with the inner recessed tapered recesses 27 formed in the support shaft bracket 19 to engage and position them. An engagement protrusion 28 having a tapered shape is formed on the rotation boss 13. That is, as shown in FIGS. 5 and 6, when the speed change lever 10 reaches the neutral position, the engagement protrusions formed at four positions on the sliding contact surface of the rotating boss portion 13 at predetermined intervals in the circumferential direction. Numeral 28 indicates the engaging projection 2 on the sliding contact surface of the support bracket 19.
The engaging recesses 27 are formed at four positions corresponding to the positions 8 and engage with each other for reliable positioning. At this time, the engaging protrusion 28 receives a pressing force on the support shaft bracket 19 side by the urging force of the coil spring 24, so that the engaging engagement is surely and quickly performed. . Moreover,
Since the engagement protrusion 28 and the engagement recess 27 are each formed in a taper shape, when the gear shift operation is performed from the neutral position to either the forward or backward movement, a smooth guide gear operation is performed by the riding guide action on the tapered surface. You can do it. The friction holding mechanism A is configured to release its friction holding action when the brake pedal 29 is depressed. That is, as shown in FIG. 4, a pair of stepped bolts 30 of the sleeve 23 are screwed and mounted inward in the radial direction, and a tip small diameter portion 30a of the bolt 30 is formed on the cylinder shaft 12 in an oblique direction. Ditch 3
1 is engaged. The arm 32 and the brake pedal 29 formed on the sleeve 23 are connected to the operation wire 3
3 through the interlocking linkage, the sleeve 2 with the brake operation
When the bolt 3 is rotated in an interlocking manner, the tip small diameter portion 3 of the bolt 30 is
The sleeve 23 slides to the spring side against the biasing force of the coil spring 24 by the engaging action of the engagement groove 0a and the engaging groove 31, and the friction holding action of the multi-plate friction mechanism 22 is released. Further, the hydrostatic stepless speed change device 3 is constructed so that the speed change operation can be performed also by the pedal 34.

It should be noted that although reference numerals are given in the claims for facilitating the comparison with the drawings, the present invention is not limited to the configuration of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a front view of a gear shift lever installation portion.

FIG. 2 is a side view of a gear shift lever installation portion.

FIG. 3 is a cutaway front view of the friction holding mechanism.

FIG. 4 is a sectional view of a friction releasing mechanism.

FIG. 5 is a side view of the neutral holding mechanism.

FIG. 6 is a cutaway plan view of the neutral holding mechanism.

FIG. 7: Side view of the entire agricultural tractor

[Explanation of symbols]

 3 Continuously Variable Transmission 10 Human Control Lever 11 Spindle 13 Rotating Boss 19 Spindle Bracket 24 Spring 27 Engagement Recess 28 Engagement Projection A Friction Holding Mechanism

Claims (1)

[Claims] 1. A continuously variable transmission (3) for a traveling drive system of an airframe.
This continuously variable transmission (3) is configured so as to be able to perform a gear shift operation by swinging the manual operation lever (10), and friction holding the manual operation lever (10) at an arbitrary gear shift operation position. A gear shift operation structure of a work vehicle provided with a holding mechanism (A), wherein a rotary boss portion (13) of the manual operation lever (10) externally fitted relative to a spindle (11) is fitted. The friction holding mechanism (A) is configured to press and urge the support bracket (19) against the support shaft bracket (19) by friction, and the rotation boss (13) and the support shaft bracket (19). ) With a tapered tapered engagement projection that enters into and engages with the inner narrowed tapered engagement recess (27) formed in the support shaft bracket (19) at the gear shift neutral position. (28) is formed on the rotating boss (13) Speed change operation structure of a work vehicle.