JPH038427B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shift operation structure for a gear transmission mechanism that is mounted on a traveling aircraft or the like and in which the shift operation is performed by two or more shift forks.

In general, a gear transmission mechanism mounted on a traveling aircraft etc. may cause damage such as putting a worker in a dangerous situation if certain conditions are met for the gear shifting operation.

For example, when the transmission mechanism of an agricultural management machine is composed of a transmission mechanism for the main transmission and a transmission mechanism for the auxiliary transmission, during work with the transmission mechanism for the auxiliary transmission set to the highest speed. If the transmission mechanism for the main gear is operated in the backward direction for some reason, regardless of the worker's will, the control machine will move backwards at high speed, and there is a risk that the tiller claws attached to the control machine may get caught in the worker's feet. It was hot.

For this reason, conventionally, the above conditions have been prevented by incorporating various check mechanisms in the gear shift operation system, but adding special check members and mechanisms increases the number of parts and processing steps. This led to an increase in costs.

The present invention has been made in view of the above-mentioned circumstances, and provides a rational arrangement of shift forks and a shift fork operation structure while maintaining the possibility of arbitrary gear shifting operations except when conditions are met. 2 without requiring any special check members or mechanisms.
The purpose is to prevent two speed change operation conditions from being met and to inexpensively manufacture a speed change operation structure that does not cause any damage caused by meeting certain conditions for speed change operation.

The present invention is characterized in that a second shift fork is located near the first shift fork and is shifted parallel to the first shift fork by an inclined cam mechanism that operates as the shift fork shaft rotates. is loosely fitted to the shift fork shaft, and the first and second shift forks are configured so that a portion of both shift forks interfere with each other at a certain shift position, and the second shift fork can interfere with each other. At a certain shift position, the cam of the inclined cam mechanism is configured to act as a linear cam portion along the rotational direction of the shift fork shaft, and its effects are as follows.

With the above configuration, when the second shift fork is located at a position other than the interference position, the first shift fork can be arbitrarily shifted in its entire operation range, and the second shift fork can be moved to the interference position in advance. When the first shift fork is set to the operating position, a part of the operating range of the first shift fork is interfered with by the second shift fork, making it impossible to operate the first shift fork into that operating range. Furthermore, even if the first shift fork is operated forcefully into this operating range, the linear cam portion
The shift fork is configured to prevent operation of the first shift fork without moving.

In other words, by rationally arranging the first and second shift forks and rationally modifying the operating structure of the second shift fork, it is possible to ensure that dangerous gear shifting conditions are met without the need for special check members or mechanisms. It has become possible to manufacture a safe gear shifting operation structure at a low cost.

Embodiments of the present invention will be described below based on the drawings.

The drawings show a management machine, a transmission case, etc. as an example of a machine to which a transmission case incorporating the speed change operation structure of the present invention is attached, and the details thereof will be explained below.

As shown in Figure 1, the engine 1 is installed at the front of the aircraft.
A vertically elongated transmission case 4 is provided with left and right axles 3a, 3b to which wheels or tillers can be attached to the lower end of the transmission case 4, to which drive is transmitted via an engine 1 and a belt 2. The management machine is constituted by a control handle 5 rotatably mounted around an axis P.

As shown in FIGS. 1 to 5, in the mission case 4, the driving force is input via a tension clutch mechanism 7 to a pulley 6 around which the belt 2 is wound, and the pulley 6 is attached. input shaft 8, auxiliary transmission mechanism 9, main transmission mechanism 10, brake mechanism 11, clutch mechanisms 12a and 12b that can be operated independently on the left and right sides, left and right chain interlocking mechanism 13
The input is sequentially transmitted to a and 13b to drive the left and right axles 3a and 3b.
The tension clutch mechanism 7 includes a tension pulley 14 that acts on the belt 2, a tension arm 15 that rotatably supports the tension pulley 14, a tension arm 15 that supports the tension pulley 14, and a tension arm 15 that is supported coaxially with a swing shaft 16 of the tension arm 15. A swinging arm 17 is arranged to be able to press the other end contact portion 15a of the tension pulley 14 of the arm 15, and the tension pulley 14 arranged at the swinging end of the swinging arm 17 is moved in the tensioning direction. Spring 1 that maintains the clutch in the engaged state.
8, and an operating lever 20 which is interlockingly connected to the swinging arm 17 via a wire 19 and is disposed on the operating handle 15.
Further, this tension clutch mechanism 7 is linked with the brake mechanism 11 so that the brake mechanism 11 operates at the same time as the tension clutch mechanism 7 is operated. That is, by operating the lever 20 from the clutch 7 engagement position indicated by A in the figure to the position indicated by B in the figure, the clutch mechanism 7 is disengaged, and from position B to the position indicated by C in the figure. By operating the lever 20, the operating arm 11a of the brake mechanism 11
A contact member 22 disposed through a spring 21 contacts the wire end member 19a and the brake mechanism 11
It is starting to operate. Further, at this time, a stopper 23 is provided to restrict the swinging of the tension arm 15 so that the swinging range of the tension arm 15 does not become large, and the tension arm 15 that has been cut is prevented from swinging unnecessarily. A spring 24 is disposed across the tension arm 15 and the swing arm 17 to prevent this from happening.

Next, the configurations of the sub-transmission mechanism 9 and the main transmission mechanism 10 will be described below.

The sub-transmission mechanism 9 includes a second shaft gear 25 that is slidably fitted onto the input shaft 8 through a spline, and a boss portion 27a of the second shaft gear 25 that is attached to the shift fork shaft 26 to shift the second shift gear 25.
is composed of a second shift fork 27 that is loosely fitted via a cam mechanism 28, and a sub-shift lever 29 that rotates the shift fork shaft 26,
The main transmission mechanism 10 also includes a first shift gear 3 which is slidably fitted onto a rotating shaft 10a via a spline to which the driving force from the sub-transmission mechanism 9 is transmitted.
0, the boss portion 31 is attached to the shift fork shaft 26 to shift the first shift gear 30.
a is loosely fitted into the first shift fork 31 via the detent mechanism 32, and the tip portion 33a of the first shift fork 31 is engaged with the boss portion 31a.
The main gear shift lever 33 is configured to shift the gear shift lever 33.

The cam mechanism 28 includes an inclined cam groove 27b formed in the boss portion 27a, and a pin 34 protruding from the shift fork shaft 26 to engage with the inclined cam groove 27b.
By rotating the shift fork shaft 26 approximately half a turn, the second shift fork 27 moves to the position H in the figure.
It is possible to switch between two positions, a high-speed rotation transmission position and a low-speed rotation transmission position, which are indicated by and L.
Further, the detent mechanism 32 includes the boss portion 31a.
A ball 36 protruding from a spring 35 and four grooves 26a formed on the outer periphery of the shift fork shaft 26 allow the aircraft to move to forward positions indicated by F ₁ and F ₂ in the figure. The configuration is such that the position is set to a reverse position of the aircraft indicated by a neutral position R indicated by N. When the second shift fork 27 is shifted to the H position, the cam groove 27b is connected to a linear cam portion 27 formed continuously at the end of the cam groove.
The pin 34 engages in the shift fork shaft 2.
The linear cam portion 27c is formed in a direction perpendicular to the axis of the shift fork shaft 26 so as not to move in response to an external force along the axis of the shift fork 26, and the second shift fork 27 and the first shift fork 31 are Second
When the shift fork 27 is in the H position and the first shift fork 31 is in the N position, the positions of the bosses 27a and 31a are set so that the opposing surfaces of the bosses 27a and 31a are in substantially contact with each other. In other words, when the second shift fork 27 is set to the H position, the first shift fork 31 cannot be operated to the R position, and even if this operation is performed forcefully, the second shift fork 31 cannot be moved to the R position. 27 does not move due to the action of the linear cam portion 27c.

6 and 7, the second shift fork 2
7 is set to high-speed rotation transmission position H, the first
Another embodiment of the present invention is shown in which the shift fork 31 cannot be operated to the rearward position R of the aircraft. In other words,
In the case shown in FIG. 6, the operating structures of the first and second shift forks 31 and 27 are substantially the same when compared with the above-described embodiment, but each shift fork 31 and 27 has a separate shift fork axis. 26A, 2
It differs in that it is fitted externally to 6B, and
In order to prevent the first shift fork 31 from being operated to the R position when the second shift fork 27 is set to the H position, the shift fork shafts 26A are placed at positions where the boss portions 31a and 27a of the respective shift forks 31 and 27 interfere. , 26B are arranged in close proximity to each other, and similar effects can be obtained. Also, what is shown in FIG. 7 is the first shift fork 31 and the boss portion 31a of the configuration described above based on FIG.
They differ in that a shift fork shaft 26A that is fitted externally is fixed, and the first shift fork 31 is shifted by operating this shift fork shaft 26A in the axial direction, but the structure is the same in other respects. When the second shift fork 27 is set to the H position, the first shift fork 31 cannot be operated to the R position.

[Brief explanation of the drawing]

The drawings show an embodiment of the speed change operation structure according to the present invention, FIG. 1 is an overall side view of the management machine, FIG. 2 is a longitudinal cross-sectional rear view of the transmission case, and FIGS. 3 and 4 show the speed change operation structure. FIG. 5 is a schematic side view showing the relationship between the clutch mechanism and the brake mechanism, and FIGS. 6 and 7 are schematic rear views showing other embodiments of the speed change operation structure. 26... Shift fork shaft, 27... Second shift fork, 27a... Boss, 27b... Inclined cam groove, 27c... Linear cam portion, 28... Inclined cam mechanism, 31... First shift fork, 34 ……pin.

Claims (1)

[Scope of Claims] 1. A second shift fork 31 which is shifted in the vicinity of the first shift fork 31 in parallel with the first shift fork 31 by an inclined cam mechanism 28 that operates in accordance with the rotation of the shift fork shaft 26. shift fork 27
is loosely fitted to the shift fork shaft 26, and when the first and second shift forks 31, 27 are at a certain shift position, both shift forks 31, 2
Parts of 7 are configured to interfere with each other, and
When the second shift fork 27 is at a certain shift position where it can interfere, the cam of the inclined cam mechanism 28 acts on a linear cam portion 27c along the rotational direction of the shift fork shaft 26. Operation structure. 2. The shift operation structure according to claim 1, wherein the first shift fork 31 is loosely fitted and supported on the shift fork shaft 26 on which the second shift fork 27 is loosely fitted so as to be shiftable and rotatable. . 3 The inclined cam mechanism 28 has the inclined cam groove 2 formed in the boss 27a of the second shift fork 27.
7b, and a pin 34 provided on the shift fall shaft 26 and engaged in the inclined cam groove 27b.
The speed change operation structure described in section. 4. The first shift fork 31 is for main shifting including reverse movement, and the second shift fork 27 is for auxiliary shifting of two high and low stages, and the shifting position where these first and second shift forks 31, 27 interfere 3. The speed change operation structure according to any one of claims 1 to 3, wherein is a reverse/high speed position.