JPH0434138Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a dust seal disposed in an annular space between the inner periphery of the lower end of a steering column and a steering shaft.

<Prior Art> As shown in FIG. 5, a dust seal 5 is usually disposed in an annular space between the inner periphery of the lower end of the steering column 1 and the steering shaft 3.

FIG. 3 shows an example of a conventional dust seal.

It consists of a fixed ring part 7 that fits tightly into the inner periphery of the lower end of the steering column 1, a seal ring part 9 that tightly fits the outer periphery of the steering shaft 3, and a flexible membrane part 11 that connects both ring parts.

In the above, the fixing ring portion 7 is provided with rigidity by the insert ring 13 having an L-shaped cross section from the viewpoint of installation stability. Further, the cross section of the flexible membrane portion 11 is usually U-shaped (arc-shaped), and furthermore, the seal ring portion 9 has annular grooves 9a, 9 on the inner and outer circumferential surfaces from the viewpoint of sealing performance and sliding property.
b is formed.

<Problems to be Solved by the Invention> However, the dust seal having the above structure may cause problems in sealing performance if the steering shaft 3 is significantly eccentric when installed in an actual vehicle.

The reason for this is that when the steering shaft 3 is significantly eccentric, the flexible membrane part 11 has a U-shaped cross section and lacks flexibility, and cannot sufficiently follow the movement of the shaft, causing the seal to fail. The inner periphery i of the ring portion 9 is flattened as shown in FIG. 4, and becomes an ellipse whose major axis is a line connecting the compression side and the non-compression side, and the seal ring portion 9 and the steering shaft 3 are formed on the non-compression side. It turns out that this is because gaps tend to form between the two.

The above sealing problem can be solved to some extent by providing a large tightening margin for the seal ring portion 9 against the steering shaft 3, but the seal ring portion 9
This is undesirable as it deteriorates the sliding properties.

<Problems for Solving the Problems> In order to solve the above problems, the inventor of the present invention made extensive efforts in development, and as a result, was able to come up with a dust seal for a steering column having the following configuration.

A dust seal disposed in an annular space between the inner periphery of the lower end of the steering column and the steering shaft, the fixing ring part fitting tightly into the inner periphery of the lower end of the steering column, and the seal ring tightly fitting to the outer periphery of the steering shaft. and a flexible film part that connects both ring parts, the cross-sectional shape of the flexible film part is V-shaped, and the top of the V-shape is a bending point of the bending motion. It is characterized by being thinner than the other parts.

<Example> An example of the present invention will be described below based on illustrated examples. Note that the same parts as in the conventional example are given the same reference numerals, and a part of the explanation will be omitted.

As shown in FIG. 1, the cross-sectional shape of the flexible membrane part 12 connecting between the fixed ring part 7 and the seal ring part 9 is V-shaped in cross-section, and the top part 12a of the V-shape is bent when it moves. The thickness of the flexible membrane portion 12 is thinner than that of other portions so as to form a curved portion.

Here, the aspect of the thin wall of the V-shaped top of the above-mentioned flexible membrane part is such that the wall thickness is gradually reduced from the rising part as shown in FIG. 2A, or by forming a notch N as shown in FIG. 2B. An embodiment in which the wall is substantially thinner is considered.
Further, the opening angle of the V-shape is usually 30 to 60 degrees. In addition, the film thickness of the V-shaped top part is 1.0 to 1.5 mm when the average film thickness of the flexible film part 12 is, for example, 2.5 mm.
shall be.

This dust seal is manufactured using chloroprene rubber, which has excellent weather resistance, grease resistance, and heat resistance.
It is molded by injection, transfer, etc. using synthetic rubber materials such as PVC blend nitrile rubber.

Next, how the dust seal of this embodiment is used will be explained.

As in the conventional case, after the seal ring part 9 is slid into a predetermined position on the steering shaft 3 to be temporarily attached, the fixing ring part 7 is press-fitted and fixed to the lower end of the steering column 1, that is, when tightened. Fix the dust seal in place.

In this state, even if a large eccentricity occurs in the steering shaft 3, since the top part 12a of the flexible film part 12 having a V-shaped cross section is a bent part that is thinner than other parts, the steering shaft of the flexible film part 11 3 has good followability. Therefore, since the seal ring portion 9 is maintained in a substantially perfect circular shape without becoming flattened, a gap is generated between the seal ring portion 9 on the non-compressible side of the flexible membrane portion 11 and the outer periphery of the steering shaft 3. There is almost no risk, and there are no problems with sealing performance.

<Operation and Effect of the Invention> As described above, the steering column shift of the present invention is a dust seal disposed in the annular space between the inner periphery of the lower end of the steering column and the steering shaft, and is tightly fitted to the inner periphery of the lower end of the steering column. In the structure consisting of a fixed ring part that fits, a seal ring part that fits tightly on the outer periphery of the steering shaft, and a flexible membrane part that connects both ring parts, the cross-sectional shape of the flexible membrane part is V-shaped. In addition, since the top of the V-shape is made thinner than the general portion so that it occasionally becomes a curved portion during flexural movement, the following functions and effects are achieved.

Even if a large eccentricity occurs in the steering shaft 3 when the dust seal is installed on an actual vehicle, the top part 12a of the flexible membrane part 12, which has a V-shaped cross section, is a bent part that is thinner than other parts. The ability to follow the steering shaft 3 is good. Therefore, the seal ring portion 9 does not flatten into an elliptical shape as in the conventional case, but maintains its substantially perfect circular shape. Therefore, there is almost no possibility that a gap will occur between the seal ring part 9 on the non-compressible side of the flexible membrane part 11 and the outer periphery of the steering shaft 3, and when the steering shaft is eccentric, there is no problem in sealing performance as in the past. There is no risk of this happening.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a dust seal according to an embodiment of the present invention, and FIGS. 2A and 2B are partially enlarged views showing the thin walls at the V-shaped top of the flexible membrane portion of the dust seal in FIG. Figure 3 is a cross-sectional view of the installation state of a conventional dust seal, Figure 4 is a model diagram of the shape relationship between the shaft and the seal ring when the steering shaft is largely eccentric, and Figure 5 is an automobile showing the installation location of the dust seal for the steering column. FIG. DESCRIPTION OF SYMBOLS 1...Steering column, 3...Steering shaft, 5...Dust seal, 7...Fixing ring part, 9...Seal ring part, 11, 12...
Flexible membrane part.

Claims (1)

[Scope of Claim for Utility Model Registration] A dust seal disposed in an annular space between the inner periphery of the lower end of the steering column and the steering shaft, the fixing ring part fitting with the inner periphery of the lower end of the steering column in an interference fit; It consists of a seal ring part that tightly fits on the outer periphery of the shaft, and a flexible membrane part that connects the two ring parts, and the cross-sectional shape of the flexible membrane part is V-shaped, and the top of the V-shape is A dust seal for a steering column, characterized in that a flexure membrane part is thinner than other parts so as to occasionally form bending points during flexure movement.