JPS6253846B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shaft support structure for a resin shift fork used for switching between a two-wheel drive vehicle and a four-wheel drive vehicle.

Conventionally, two-wheel drive (hereinafter referred to as "two-wheel drive") used in four-wheel drive vehicles
For example, there is a mechanism for switching between 2WD) and 4-wheel drive (hereinafter referred to as 4WD) as shown in Figure 1.

In FIG. 1, reference numeral 1 denotes a rear output shaft to which driving force from the engine is constantly transmitted, and a front output shaft 2 is provided opposite to the direction of the rear output shaft. A rear spline 3 and a front spline 4 are formed on the outer circumferences of the rear output shaft 1 and the front output shaft 2, respectively, and in the illustrated 2WD state, the coupling sleeve 5 provided with the fork groove is on the rear spline 3 side. Reference numeral 7 designates a shift rod that moves in the axial direction when the shift lever is operated. A shift fork 8 made of resin is attached to the shift rod 7, and a fork pawl 9 in a bifurcated shape is inserted into the fork groove 6 of the coupling sleeve 5. They are mated.

Therefore, in switching from 2WD to 4WD, the shift rod 7 moves the shift fork 8 to the right to fit the coupling sleeve 5 into the front spline 4 and transmit the driving force of the rear output shaft 1 to the front output shaft 2. It becomes like this.

FIG. 2 shows in detail the mounting structure of the shift fork 8 to the shift rod 7. A pair of stepped collars 12 and 13 are installed in the shaft hole 10 of the shift fork 8 with a spring 11 interposed therebetween. , the shift rod 7 is inserted into the stepped collars 12, 13, and the shaft hole 10 of the stepped collars 12, 13 is inserted.
The positioning of the stepped collars 12 and 13 with respect to the shift rod 7 is performed by the stopper rings 14 and 15 fitted into the opening of the shaft hole 10 coming into contact with the large diameter portion of the collar. This is done by contacting the small diameter portions of the collars 16 and 17.

The shaft support structure of the shift fork shown in FIG. 2 is known as a so-called waiting mechanism. For example, when a shift operation is performed to switch to 4WD as shown in FIG. Move to the right and shift fork 8
As a result, the coupling sleeve 5 also moves to the right. However, since the front spline 4 and the rear spline 3 are in phase with each other at the initial stage, the coupling sleeve 5 is in a 2WD state where it stops at the engagement position of the front spline 4.

At this time, the stepped collar 12 of the shift fork 8
Stopper ring 1 due to movement of shift rod 7
6 puts the spring 11 in a compressed state, and the shift fork 8 becomes in a state in which the coupling sleeve 5 is pushed to the right by the repulsive force of the spring 11. As the vehicle moves in this state, the moment the rear spline 3 and the front spline 4 are in phase, the coupling sleeve 5 moves the spring 11.
It fits into the front spline 4 with the force of , and the 4WD
The switch to is completed.

However, in the shaft support structure of such a conventional resin shift fork, oil and air are sealed in the shaft hole 10 of the shift fork 8 through the stepped collars 12 and 13. As shown in Figure 3, when the shift rod 7 moves, the oil and air are discharged slowly, so the pumping action of the compressed air makes the movement of the shift rod 7 heavy, and the phases of the rear spline 3 and front spline 4 are not aligned. Regarding the fitting of the coupling sleeve 5 by spring force,
Since the intake of air into the spring storage portion is slow, there is a possibility that a negative pressure state may occur and the coupling sleeve 5 may not be fitted into the front spline 4 quickly.

Therefore, it is conceivable to provide the shift fork 8 with a ventilation hole 18 that communicates the spring storage part with the outside as shown by the broken line, but since the ventilation hole 18 has to be formed by drilling, it is time-consuming and labor-intensive. Drilling tends to cause burrs on the circumferential surface of the shaft hole of the shift fork, and the occurrence of burrs hinders the movement of the stepped collar within the shaft hole.

The present invention has been made in view of the above, and is a shaft of a resin shift fork having a simple structure and a waiting mechanism that allows oil and air sealed in the shaft hole of the shift fork to communicate with the outside. The purpose is to provide a supporting structure.

In order to achieve this object, the present invention provides ventilation grooves for communicating the housing portion of the spring with the outside on the outer circumferential surface of the stepped collar incorporated in the shift fork shaft hole or on the inner circumferential surface of the stepped collar that slides in contact with the shift rod. This is what I did.

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

FIG. 4 is a sectional view showing one embodiment of the present invention.

First, to explain the configuration, 7 is a shift rod,
Reference numeral 8 designates a shift fork made of resin that is attached to the shift rod 7. The shift fork 8 has a shaft hole 10 through which the shift rod 7 is inserted, and is divided into two parts on the lower left side that fit into the fork groove of the coupling sleeve. Fork claws 9 are integrally formed. A pair of stepped collars 12 and 13 are incorporated into the shaft hole 10 of the shift fork 8, and the stepped collars 12 and 13 abut against the stepped portions of stopper rings 14 and 15 fitted into the open end of the shaft hole 10. Shaft hole 1
Stepped collar 1 by stopper rings 16 and 17 positioned within 0 and fitted to shift rod 7
It is positioned with respect to the shift rod 7 by abutting against the small diameter ends of the stepped collars 12 and 13, and a spring 11 is interposed between the stepped collars 12 and 13.

Such a structure is similar to that of the conventional device, but in addition, in the present invention, a ventilation groove 20 is provided in the axial direction on the circumferential surface of the large diameter portion of the stepped collar 12 incorporated on the left side, which communicates the spring storage portion with the outside. is formed.

Figure 5 shows the stepped collar 1 in the embodiment shown in Figure 4.
2, the stepped collar 12 has a small diameter portion 12a and a large diameter portion 12.
The shaft hole 12c has a stepped outer circumferential shape with a stepped outer circumferential shape, and a shaft hole 12c into which a shift rod is inserted is formed, and a ventilation groove 20 running in the axial direction is formed on the circumferential surface of the large diameter portion 12b.

Next, to explain the operation of the present invention, when the shift rod 7 is moved to the right in order to switch to 4WD, the stepped collar 12 is pushed by the stopper ring 16 fitted to the shift rod 7, compressing the spring 11 and compressing it. The force of the spring 11 pushed the shift fork 8 to the right, and the fork pawl 9
Press the coupling sleeve that is fitted onto the end of the front spline of the front output shaft located on the right side.

At this time, by moving the stepped collar 12, the spring 1
1 will be compressed, but since an axial ventilation groove 20 is formed in the large diameter part of the stepped collar 12, the air and oil present in the spring housing will pass through the ventilation groove 20 to the outside. The movement of the shift rod 7 does not become heavy due to the pumping action of the air discharged to the spring storage section 10 and confined in the spring housing section 10.

Next, when the splines of the rear output shaft and the splines of the front output shaft match in phase with the spring 11 being compressed, the coupling sleeve fits into the front spline due to the force of the spring 11, and the previously compressed The spring 11 returns to the initial state shown in FIG. 4, and the volume of the spring housing increases at this time because outside air easily flows in through the ventilation groove 20 formed in the stepped collar 12, so that the rear output shaft and front output The coupling sleeve can be quickly fitted by the spring force when the phases of the shaft splines match.

FIG. 6 is a cross-sectional view and a side view showing another embodiment of the stepped collar used in the present invention. In the embodiment of FIG. The embodiment is characterized in that a ventilation groove 20 is formed on the inner peripheral surface of the shaft hole 12c into which the shift rod is inserted, and the spring housing portion of the shift fork is placed in the ventilation groove of the shaft hole 12c, similar to the stepped collar shown in FIG. 20 to the outside, and can prevent the pumping action when the spring is compressed and the generation of a negative pressure state in the spring housing when the spring returns to its original state.

In addition, when the ventilation groove 20 is formed in the shaft hole 12c of the stepped collar 12 shown in FIG. 6, the stopper ring 16 fitted on the shift rod 7 is placed at the external opening position of the ventilation groove 20, as is clear from FIG. Since there is a risk that the ventilation groove 20 may be blocked by contact, it is desirable that the outer opening of the ventilation groove 20 be widened so as to extend beyond the contact area of the stopper ring 16.

As described above, according to the present invention, as a shaft support structure for a resin shift fork equipped with a waiting mechanism, a pair of stepped collars are slidably assembled between a shift fork shaft hole and a shift rod. A ventilation groove is formed on the outer peripheral surface that slides into the shift fork shaft hole or on the inner peripheral surface that slides into the shift rod to communicate the spring housing to the outside, so that the spring inside the shift fork that is partitioned by stepped collars on both sides. The storage compartment is always in communication with the outside through the ventilation groove of the stepped collar, which reliably prevents the movement of the shift rod from becoming heavy due to the pumping action when the spring is compressed during shift operation, and also prevents compression. Since the return of the spring is not obstructed, the coupling sleeve can be quickly fitted into the shaft spline against the spring force, and the effect is that the smooth operation of the resin shift fork with a waiting mechanism can be guaranteed. is obtained.

In addition, in the above embodiment, ventilation grooves are formed in one of the stepped collars, but it is inconvenient to separately manufacture a stepped collar with ventilation grooves and a stepped collar without ventilation grooves. Therefore, it is of course possible to use stepped collars on both sides that have the same ventilation grooves.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing an example of a mechanism for switching between 2WD and 4WD in a 4-wheel drive vehicle, Fig. 2 is a sectional view showing a conventional shift fork shaft support structure, and Fig. 3 is a shift operation using the conventional structure. FIG. 4 is a cross-sectional view showing an embodiment of the present invention, FIG. 5 is a cross-sectional and side view showing the stepped collar of the embodiment of FIG. FIG. 6 is a cross-sectional and side view showing another embodiment of the stepped collar. 1: Rear output shaft, 2: Front output shaft, 3: Rear spline, 4: Front spline, 5: Coupling sleeve, 6: Fork groove, 7: Shift rod, 8: Shift fork (made of resin), 9:
Fork claw, 10: Shaft hole, 11: Spring, 1
2, 13: stepped collar, 14, 15, 16, 1
7: Stopper ring, 20: Ventilation groove.

Claims (1)

[Scope of Claims] 1. A pair of stepped collars are slidably assembled into the shift fork shaft hole with a spring interposed between them, and the shift fork is shaft-inserted into the shift rod via the stepped collars, and the stepped collars are inserted into the shift rod via the stepped collars. The position of each of the rods is regulated by the contact of the stopper ring fitted to the shift rod with the outer small diameter part, and the position of each of the shift rods is regulated by the contact of another stopper ring fitted into the opening side of the shift fork shaft hole with respect to the large diameter part. A shaft support structure for a resin shift fork with position regulation, characterized in that a shaft hole sliding surface of the stepped collar or a shift rod sliding surface is provided with a ventilation groove that communicates the spring storage portion with the outside. Shaft support structure of manufactured shift fork.