JPH08247285A - Spring pin structure for fixing shift forks - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a spring pin structure for fixing a shift fork, which is in close contact with the pin hole wall surface over the entire surface in the circumferential direction in a press-fitted state. [Composition] Spring pin 16 in the state of being press-fitted into the pin hole.
The thickness is temporarily reduced in the direction from the point c to the point d so that the stress is uniform in the circumferential direction. Since the outer peripheral surface of the spring pin 16 has a shape that forms a perfect circle when the joint portion d comes into close contact by press-fitting, the entire outer surface of the spring pin 16 comes into close contact with the outer wall of the pin hole with a substantially uniform stress.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spring pin structure for fixing a shift fork applied to a vehicle transmission or the like.

[0002]

2. Description of the Related Art FIG. 3 is an exploded perspective view showing a shift rail and a shift fork of an automobile transmission, wherein 1 is a shift rail and 2 is a shift fork. The shift fork 2 has an insertion hole 3 and a pin hole 4 for the shift rail 1. In addition, the shift rail 1 is provided with a pin hole 5 that corresponds to the pin hole 4 of the shift fork 2 and forms a through hole at a predetermined fixed position.

As shown in FIGS. 4 to 6, the shift fork 2 is fixed to the shift rail 1 by inserting the shift rail 1 into the insertion hole 3 by a predetermined amount so that the pin holes 4 and 5 are aligned with each other. The spring pin 6 is press-fitted into the through hole. As shown in FIG. 7, the spring pin 6 is formed by forming a spring steel plate material having a uniform thickness into a substantially hollow cylindrical shape. It should be noted that chamfers 6a are provided on the outer peripheral corners of both ends of the spring pin 6 to facilitate press fitting.

[0004]

By the way, since the above-mentioned conventional spring pin 6 is formed by forming a spring steel plate material having a uniform wall thickness into a substantially hollow cylindrical shape, the spring pin 6 is formed.
As shown in the stress distribution diagram of FIG. 8, the internal stress is highest at point c at the center in the circumferential direction and lowest at point d at the joints at both ends. When the spring pin 6 having such a stress distribution is press-fitted into the pin holes 4 and 5, it is elastically deformed into an elliptical shape as shown in FIG. It was difficult to bring them into close contact. Note that the elliptical shape of the spring pin 6 in FIG. 9 is shown as being more extreme than it actually is in order to facilitate understanding.

When the shift force F (see FIG. 4) is applied to this state, the stress at the point c becomes higher, and in some cases, the spring pin 6 may come out or be damaged. Also, the spring pin 6
Since the radial pressure applied to the shift fork 2 is high at the point c, when the aluminum shift fork 2 is adopted for the purpose of weight reduction, which tends to increase in recent years, the pin hole 4
However, it was inconvenient because of the possibility of deformation.

In order to eliminate the above-mentioned inconvenience, the strength (elasticity) of the spring pin 6 may be improved,
Specifically, it is conceivable to increase the thickness of the spring steel plate material or double the pins. However, the spring pin having the increased thickness has a problem that a large force is required at the time of molding or press fitting into the pin hole, and the duplicated pin has a problem that the press fitting man-hour increases. Further, it is conceivable to increase the diameter of the spring pin, but due to the fact that the pin hole 5 is formed in the shift rail 1, there is a limit to the expansion of the diameter of the spring pin.

[0007] Therefore, an object of the present invention is to provide a spring pin structure which is in tight contact with the pin hole wall surface over the entire surface in the circumferential direction in a press-fitted state, thereby achieving an increase in strength.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, in which a shift rail is inserted into a shift fork and then press-fitted into a pin hole penetrating the shift rail to shift the shift fork. In a spring pin structure for fixing a shift fork fixed to a rail, a wall thickness of the spring pin is changed so that a uniform stress is applied in a circumferential direction in a press-fitted state. is there.

[0009]

According to the above-mentioned means of the present invention, since the stress of the spring pin press-fitted into the pin hole is uniform in the circumferential direction,
The pin wall is adhered almost uniformly over the entire circumference. Therefore, the stress at the point c can be reduced as compared with the conventional structure having a uniform thickness, and a large local stress can be prevented from acting.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a spring pin structure for fixing a shift fork according to the present invention will be described below with reference to FIGS.

FIG. 1 shows the spring pin 16 in a natural state (before press-fitting). The point c at the center in the circumferential direction has the maximum thickness, and the point is toward the point d at both ends (direction of arrow 17). A spring steel plate material whose thickness is temporarily reduced is formed into a cylindrical shape, and the pin holes 4,
The stress in the state of being press-fitted in No. 5 is made uniform in the circumferential direction (see FIG. 2). Further, the spring pin 16 is formed so that the outer peripheral surface becomes a perfect circle in a press-fitted state in which the joint portion d is in close contact. Is provided.

The spring pin 16 described above is attached to the pin holes 4,
If the structure of fixing the shift fork 2 to be press-fitted into 5 is adopted, since the outer peripheral surface of the spring pin 16 in the press-fitted state is in close contact with the entire circumference of the wall surface of the pin holes 4 and 5 due to the uniform stress, the shift force F acts. Even if you receive it, it will not come off easily. In addition, since the stress at the point c can be reduced as compared with the conventional spring pin having a uniform thickness, a large stress is not locally applied, and the fatigue strength can be increased. Even when the shift fork 2 is made of aluminum for the purpose of weight reduction in recent years, the pin hole 4 can be prevented from being deformed due to the reduction of the surface pressure at the point c, which improves durability and reliability. Can be improved.

[0013]

According to the present invention described above, since the wall thickness is changed so that the stress is evenly distributed in the circumferential direction in the press-fitted state, the strength of the spring pin is increased, and the press-fitting of the spring pin is easy and difficult to remove. It becomes possible to provide.

Further, it is possible to prevent the pin hole of the shift fork from being deformed, and it is also effective in improving durability and reliability.

[Brief description of drawings]

FIG. 1 is a view showing an embodiment of a spring pin structure for fixing a shift fork according to the present invention, (A) is a plan view,
(B) is a front view.

FIG. 2 is a stress distribution diagram showing a state in which the spring pin of FIG. 1 is press-fitted into a pin hole.

FIG. 3 is an exploded perspective view showing a shift rail and a shift fork of an automobile transmission.

FIG. 4 is a vertical sectional view showing a fixing structure of a shift fork.

FIG. 5 is a sectional view taken along line AA of FIG. 4;

FIG. 6 is a view (plan view) taken in the direction of arrow B in FIG.

FIG. 7 is a perspective view showing a conventional spring pin structure for fixing a shift fork.

8 is an internal stress distribution diagram of the conventional spring pin shown in FIG.

9 is a plan view showing the elastic deformation of the conventional spring pin shown in FIG. 7 in a state where the spring pin is press-fitted in order to explain the problem.

[Explanation of symbols]

 1 shift rail 2 shift fork 3 insertion hole 4,5 pin hole 6,16 spring pin

Claims (1)

[Claims] 1. A spring pin structure for fixing a shift fork for fixing the shift fork to the shift rail by inserting the shift rail into the shift fork and then press-fitting the pin into the pin hole passing through the shift fork. A spring pin structure for fixing a shift fork, characterized in that the wall thickness of the spring pin is changed so as to have a uniform stress.