JPH07125558A - Shift operating structure of transmission gear - Google Patents

Abstract

PURPOSE:To assemble or set a transmission gear simply in dispensing with a pin setting A operation at the inner part of a case by setting up a first cam part formed in a shift fork and a second cam part integrally formed on the inner surface of a transmission case in a state that both of then are engaged with each other. CONSTITUTION:A shift fork consists of a first cam part 13k to be externally fitted in a fulcrum shaft 12 by means of splining, and a fork 13A free of relative rotation with the former and externally fitted in it unmovably in the axial direction, while a run-over cam mechanism A is made up of an engagement between a projectional second cam part 5k integrally formed on the inner surface of an axle case 5 and the first cam part 13k. According to this structure, when an operating arm 15 is operated into rotation, the run-over cam mechanism A operates its run-over action and thereby the fork par 13A shifts in the left, and a shifter 10 interlocks with an engaging part, whereby a differential locking state is manifested. With this constitution, a fixed cam is omitted and thereby the facilitation of assembly is well promotable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift operation structure of a transmission device such as a diff lock device and a transmission.

[0002]

2. Description of the Related Art For example, the operation structure of a diff lock device disclosed in Japanese Utility Model Laid-Open No. 55-63218 discloses a shifter which is loosely fitted on a support shaft and a pressing member which is fitted on the support shaft so as to rotate integrally. A member and a member form a riding cam mechanism, and a shifter is reciprocally shift-operated by rotating an operation arm attached to a case outer portion of a support shaft. Such a structure is generally used. It was a shift operation structure.

[0003]

However, in the above structure, it is necessary to perform the roll pin fixing operation to the support shaft of the pressing member in the inner part of the case, and the assembling operation is troublesome and troublesome, and there is room for improvement. was there. It is an object of the present invention to improve the structure so that the shift operation structure can be reviewed so that the pin mounting operation inside the case can be eliminated and the assembly can be easily performed.

[0004]

In order to achieve the above object, the present invention is directed to a support shaft supported by a transmission case, in which a shift fork is slidably and relatively non-rotatably fitted to rotate the support shaft. The shift fork is reciprocally shiftable in the axial direction by an operation, and the lift cam mechanism is provided. The lift cam mechanism is integrally formed with the first cam portion formed on the shift fork and the inner surface of the case of the transmission case. The formed second cam portion is arranged such that both of them engage with each other.

[0005]

The riding cam mechanism functions by the relative rotation of the first cam portion, which is a non-rotatable fixed cam, and the rotatable second cam portion. Conventionally, the shift fork is the first. The cam portion and the pressing member correspond to the second cam portion. According to the above characteristic configuration, the first cam portion on the shift fork side is the rotating cam and the second cam portion is the fixed cam. Will be equivalent to. That is, the operation arm and the first cam portion rotate together, but the support shaft and the shift fork are relatively slidable, so that the first cam portion moves in the axial direction while rotating. Become. Therefore, the second cam portion formed on the case wall corresponds to a conventional fixed cam, which eliminates the need for a dedicated fixed cam and the roll pin as a fixing means for the supporting shaft and its assembling operation. be able to.

Here, several examples of the relational structure between the rotating shift fork and the shifter will be disclosed. In the case of FIG. 4, the inner surfaces of the two forks 13a, 13a of the shift fork 13 are formed in an arc centered on the axis of the support shaft 12,
It is a structure in which the shifter 10 is occluded from the side. The arc length of the fork 13a is set so as to correspond to the rotation amount or more required for the shift movement of the shifter 10.

In FIG. 5, the tip of the fork portion 13A of the shift fork 13 is formed in an arc shape centered on the shaft center of the support shaft 12 and engaged with the shifter 10 from above. It is configured to be carried around.

In FIG. 1, the shift fork 13 has a boss-like first cam portion 13k and a fork portion 13A which is fitted onto the first cam portion 13k in a state in which axial movement is impossible and relative rotation is permitted. The bifurcated fork portion 13A that engages with the shifter 10 is configured to move only in the axial direction. In any of the above cases, the conventional fixed cam can be omitted, and the axial width of the device can be reduced accordingly.

[0009]

As a result, by utilizing the case wall to make the roles of the two cam members in the riding cam mechanism opposite to the conventional ones, the compact cam can be omitted and the assembly can be done. It was possible to provide a shift operation structure capable of facilitating the shift operation.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings when applied to a diff lock device for a tractor. FIG. 1 shows the lower side of the transmission from the differential mechanism for the drive wheels of the tractor. 1 is a differential mechanism, 2 is a side brake, 3 is an axle, 4 is a differential case, 5 is an axle case, and 7 is a differential lock device.

As shown in FIGS. 1 to 3, a diff lock device 7 includes a spline portion 11a of a diff output shaft 11, a meshing portion 9a of a diff frame 9, and a shifter 10 spline fitted onto the diff output shaft 11. It is composed of a support shaft 12 that straddles the differential case 4 and the axle case 5, a shift fork 13 that is splined onto the support shaft 12, a return spring 14, and the like. The shift fork 13 is slidably and non-rotatably fitted to the support shaft 12. When the operation arm 15 outside the case is used to rotate the support shaft 12, the shift fork 13 is reciprocally shift-moved in the axial direction. A possible riding cam mechanism A is provided.

That is, the shift fork 13 is attached to the support shaft 1.
2 includes a first cam portion 13k that is spline-fitted to the spline 2 and a fork portion 13A that is relatively rotatable and axially immovably fitted to the first cam portion 13k. The riding cam mechanism A is configured by the engagement of the convex second cam portion 5k integrally formed on the inner surface of the case and the first cam portion 13k. In this structure, the first cam portion 13k rotates and moves in the axial direction as the support shaft 12 rotates, and the fork portion 13A moves only in the axial direction. That is, when the operation arm 15 outside the axle case 5 is not operated, the shift fork 13 is pressed to the right in FIG. 2 by the urging force of the return spring 14, and the meshing portion 9a.
The spline portion 11a and the spline portion 11a are maintained in a non-engaged diff operating state, and when the operation arm 15 is operated to rotate, the ride cam mechanism A moves up and the fork portion 13A moves leftward in FIG. 2 to shift the shifter. 10 engages with the engaging portion 9a, and the differential lock state appears.

The differential case 4 and the axle case 5 are line w.
The left cam is divided into right and left parts, and the raised portion of the second cam portion 5k can be integrally formed at the time of die casting of the case, and its surface processing can be omitted. Further, the urging force of the return spring 14 directly affects the shift fork 1
3 and does not act on the support shaft 12. Therefore,
Unlike the conventional case, a force that causes the support shaft 12 to move in the axial direction is not generated by the spring reaction force, and a unit (a conventional double nut outside the case corresponds to the reaction force) against the reaction force is unnecessary.

FIG. 7 shows the driving part at the front of the tractor.
A battery 17, a radiator 18, a suction type cooling fan 19, and an engine 20 are arranged on the machine body frame 16 from the front. A dustproof net 21 is mounted on the front surface of the radiator 18, and a windbreak plate 22 that covers the front and rear gap between the radiator 18 and the battery 17 is provided under the dustproof net 21.
Are attached together. The windbreak plate 22 prevents hot air that has passed through the cooling fan 19 from flowing into the front portion of the radiator 18 from below, prevents dust from falling when cleaning the dustproof net 21, and collects dust on the windbreak plate 22. It is useful as something that can be done.

A steering gear structure is shown in FIG.
23 is a handle shaft, 23a is a worm, 24 is a sector shaft, 24a is a sector gear, 25 is a pitman arm,
26 is a gear case. The sector gear 24a is a taper gear, and constitutes an adjusting mechanism B capable of adjusting the axial position of the sector shaft 24. That is, the cover case 27 that supports the end of the sector shaft 24 without a gap in the axial direction.
Is bolted to the gear case 26 via the shim 28. By changing the thickness of the shim 28, the sector gear 24a
The optimum occlusal state between the worm 23a and the worm 23a can be displayed.

[Other Embodiment] As shown in FIG. 8, the return spring 14 may be provided outside the axle case 5. In this case, it is necessary to form a flange 29 on the inner end of the case of the support shaft 12 to transmit the return urging force acting on the support shaft 12 to the shift fork 13. Further, in this embodiment, the first cam portion 13a may be formed as a convex cam and the second cam portion 5a may be formed as a concave cam. The transmission case is a concept including both the differential case 4 and the axle case 5.

It should be noted that reference numerals are added to the claims for convenience of 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]

FIG. 1 is a development view showing the structures of a differential mechanism and a differential lock device.

FIG. 2 is a sectional view showing an operation structure of a diff lock.

FIG. 3 is a partially cutaway side view showing the structure of a shift fork.

FIG. 4 is a side view showing a first different structure of the shift fork.

FIG. 5 is a side view showing a second different structure of the shift fork.

FIG. 6 is a sectional view showing a steering interlocking structure.

FIG. 7 is a partial side view showing the front part of the tractor drive part.

FIG. 8 is a development view showing another structure of the shift operation structure.

[Explanation of symbols]

 5 Transmission case 5k 2nd cam part 12 Support shaft 13 Shift fork 13k 1st cam part A Riding cam mechanism

Claims (1)

[Claims] 1. A support shaft (1) supported by a transmission case (5).
2) A shift fork (13) is slidably and non-rotatably fitted to the shift fork (13), and the shift fork (13) is axially reciprocally shiftable by a turning operation of the support shaft (12). A cam mechanism (A) is provided, and the riding cam mechanism (A) is provided on the first cam portion (13k) formed on the shift fork (13) and on the inner surface of the transmission case (5). A shift operation structure for a transmission, wherein the second cam portion (5k) formed integrally is arranged in a state in which the two (13k) and (5k) are engaged with each other.