JPH09250635A - Structure of gear shift mechanism of transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cost, to reduce the weight, and to improve the assembly property, by reducing the number of parts to compose a reversing mechanism, in a transmission having a reversing mechanism to reverse the shifting direction. SOLUTION: To a shift 3d for 1st speed/backing to slide following the shift operation of the first speed or backing, a shifter 5 forming a groove to insert one side end of a reversing lever 4 to reverse the shifting direction is fixed, and to a shift shaft 3b for 4th speed/5th speed sliding following the shift operation of the fourth speed or the fifth speed, not only a shift fork 6 for 4th speed/5 th speed is fixed, but also a shift fork 7 for 1st speed/backing is fitted slidable. And the shifter 5 and the shift fork 7 for 4th/5th speed are connected through the reversing lever 4 by making a fulcrum 4a as the center. Furthermore, a bearing 8 or a bush 9 to reduce the sliding resistance with the shift shaft 3b for 4th speed/5th speed is provided to the shift fork 7 for 1st speed/backing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a transmission gear shift mechanism, and more particularly to a technique for reducing the number of parts.

[0002]

2. Description of the Related Art Generally, the gear layout of a transmission is restricted by the required strength of the gears at each shift stage, and the shift pattern of the change lever and the shift pattern of the transmission may not match. On the other hand, the shift patterns of the change lever have a substantially common pattern, and matching this with the shift pattern of the transmission deteriorates operability.

Therefore, in order to match the shift patterns of the change lever and the transmission, it is general to provide a reversing lever for reversing the shift direction on the transmission side so as to match the shift patterns.

[0004]

However, in the conventional reversing mechanism in the shift direction by the reversing lever, as shown in FIG.
The shift operation force in which the shift direction is reversed is transmitted to the shift fork 13 fixed to the dedicated shift shaft 12. In addition, a support boss portion 1 that slidably supports the shift shaft 11 and the dedicated shift shaft 12
4a and 14b were also required. Further, when the dedicated shift shaft 12 is provided, the installation position is limited to avoid interference with other mechanisms of the transmission.
As shown in FIG. 2, the transmission case 15 is also projected outward. Therefore, the number of parts and the weight of the transmission are increased.

In view of the conventional problems as described above, the present invention reduces the cost and weight by reducing the number of parts constituting the reversing mechanism in a transmission having a reversing mechanism for reversing the shift direction. The purpose is to improve the assemblability.

[0006]

Therefore, according to the invention of claim 1, in a gear shift mechanism of a transmission having a reversing mechanism for reversing the shift direction of the shift operation force transmitted to the shift shaft, the reversing mechanism reverses. The shift fork to which the generated shift operating force is transmitted is provided separately from the shift shaft and is slidably fitted on the shift shaft to which the shift operating force is transmitted.

According to a second aspect of the present invention, a bearing for reducing sliding resistance is interposed between the shift fork and the shift shaft on which the shift fork is slidably fitted. According to a third aspect of the present invention, a bush for reducing sliding resistance is interposed between the shift fork and the shift shaft on which the shift fork is slidably fitted.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. 1 to 3 show an embodiment in which a gear shift mechanism of a transmission according to the present invention is applied to a pot case type transmission. The transmission shown in FIG. 1 reverses between first speed and reverse.

The front case 1 and the main case 2 which constitute the pot case type transmission are each formed in a substantially cylindrical shape, and the main case 2 is joined to the rear end of the front case 1. Supporting boss portions 2a and 2b for slidably supporting shift shafts 3a to 3d, which will be described later, are formed on the front and rear portions of the main case 2, and are associated with shift operation of a change lever (not shown). Shift shaft 3 that slides inside main case 2
a to 3d are fitted together. The shift shaft (hereinafter, referred to as "first speed / reverse shift shaft") 3d that slides with the change lever's first speed or reverse shift operation has a reversing lever (reversing mechanism) 4 for reversing the shift direction. A shifter 5 having a groove into which one end of is fitted is fixed. In addition, a shift shaft (hereinafter,
"4th / 5th shift shaft") 3b has 4
A shift fork 6 (hereinafter, referred to as "4th / 5th shift fork") 6 for shifting the first speed or the fifth speed is fixed, and a shift fork (hereinafter, referred to as "1 A "speed / reverse shift fork" 7) is slidably fitted. The first / reverse shift fork 7 is provided with a bearing 8 or a bush 9 as shown in FIG. 2 in order to reduce sliding resistance with the fourth / fifth shift shaft 3b.

Then, the first speed / reverse shift shaft 3d
The shifter 5 fixed to the 4th speed / 5th speed shift fork 7 slidably fitted to the 4th / 5th speed shift shaft 3b includes the 1st speed / reverse shift shaft 3d.
And a shift shaft 3b for 4th / 5th gears are connected via a reversing lever 4 which swings around a fulcrum 4a located at an intermediate portion.

Next, the operation of the gear shift mechanism having the above structure will be described. For example, considering the case where a change lever (not shown) is shifted backward, the first speed / reverse shift shaft 3d slides to the right. At this time,
The shifter 5 moves to the right as the first-speed / reverse shift shaft 3d slides, and the reversing lever 4 connected thereto swings counterclockwise about the fulcrum 4a. Then, the first speed / reverse shift fork 7, which is slidably fitted to the fourth speed / 5th speed shift shaft 3b, moves to the left (see the chain line in the figure). That is, the action of the reversing lever 4 reverses the shift direction. When shifting the change lever to the first speed, the shift direction is reversed through the same process.

Here, the feature of the gear shift mechanism according to the present invention is that the operating force reversed by the reversing lever is slidably fitted on another shift shaft provided for transmitting the shift operating force. The point is that it is transmitted to the shift fork. That is, by adopting such a configuration, the shift shaft for exclusive use of the shift fork and the support boss (see FIG. 5) which are required in the conventional gear shift mechanism are not required, and the number of parts and the weight can be reduced. In addition, in order to avoid interference between the dedicated shift shaft and the mechanism of the transmission, it is not necessary to project the peripheral wall of the transmission case outward (see FIG. 3). Weight can also be reduced.

FIG. 4 shows another embodiment in which the gear shift mechanism of the transmission according to the present invention is applied to a conventional case type transmission. In the conventional conventional case type transmission, the 4th / 5th shift shaft and the 1st / reverse shift shaft are separate bodies.
A first / reverse shift fork 7 to which the inverted shift operation force is transmitted is slidably fitted on the fifth / fifth shift shaft 3b. Therefore, the shift shaft is 1
This is unnecessary, and the number of parts can be reduced.

In the present embodiment, the shift direction of the first speed / reverse shift shaft is reversed.
The present invention is not limited to this, and other shift shafts such as a 4th / 5th shift shaft may be reversed.

[0015]

As described above, according to the first aspect of the invention, the shift fork to which the shift operation force inverted by the inversion mechanism is transmitted is provided separately from the shift fork.
Moreover, since the shift shaft to which the shift operation force is transmitted is slidably fitted on the shift shaft, the shift fork dedicated for the shift fork and the support boss, which have been required in the past, are not necessary, and the number of parts can be reduced. Weight reduction can be achieved. In addition, the need for a dedicated shift shaft eliminates the need to project the transmission case outward to avoid interference between the dedicated shift shaft and other mechanisms of the transmission. It becomes easier and the weight of the case can be reduced. Further, as the number of parts is reduced, the cost can be reduced and the assemblability can be improved.

According to the second or third aspect of the invention, the sliding of the shift fork is achieved by a bearing or a bush interposed between the shift fork and the shift shaft to which the inverted shift operation force is transmitted. Since the dynamic resistance is reduced, the shift operation of the transmission becomes smooth.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a gear shift mechanism according to the present invention.

FIG. 2 is a detailed view of a means for reducing sliding resistance provided on the above shift fork, (a) showing a bearing interposed, and (b) showing a bush interposed.

FIG. 3 is a sectional view taken along line AA in FIG. 1;

FIG. 4 is a sectional view showing another embodiment of the gear shift mechanism according to the present invention.

FIG. 5 is a sectional view showing a conventional gear shift mechanism.

6 is a sectional view taken along line BB in FIG. 5;

[Explanation of symbols]

 3b 4th / 5th shift shaft 3d 1st / reverse shift shaft 4 Reversing lever 7 1st / reverse shift fork

Claims (3)

[Claims] 1. A gear shift mechanism of a transmission having a reversing mechanism for reversing a shift direction of a shift operating force transmitted to a shift shaft, wherein a shift fork to which the shift operating force reversed by the reversing mechanism is transmitted. A structure of a gear shift mechanism of a transmission, which is provided separately from a shaft and is slidably fitted on a shift shaft to which a shift operation force is transmitted. 2. A transmission according to claim 1, wherein a bearing for reducing sliding resistance is interposed between the shift fork and a shift shaft into which the shift fork is slidably fitted. Structure of gear shift mechanism. 3. The transmission according to claim 1, wherein a bush for reducing sliding resistance is interposed between the shift fork and a shift shaft in which the shift fork is slidably fitted. Structure of gear shift mechanism.