JPH077656Y2 - Oil seal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to an oil seal mounted on a shaft such that an inner peripheral surface of a lip portion is fitted to a shaft that reciprocates.

[Problems to be Solved by Conventional Techniques and Inventions] The above-mentioned oil seal is mounted on a shaft that reciprocates. Conventional oil seals include an oil seal when the shaft reciprocates. There is a problem that frictional vibration (stick-slip) between the rib portion and the shaft may occur and a sounding phenomenon may occur.

The above-mentioned pronunciation phenomenon gives an uncomfortable feeling to the driver of the machine and the device, and especially when the pressure resistant oil seal is used under pressure, the contact area between the lip and the shaft becomes large. A loud noise is generated.

An object of the present invention is to provide an oil seal that solves the above problems of the prior art.

[Means for Solving the Problems]

According to the present invention, in the above oil seal, a circumferential groove for preventing sound generation is provided at a portion of the inner peripheral surface of the lip portion that comes into contact with the shaft, and the circumferential groove is arranged in parallel in the axial direction of the oil seal at a small pitch, The problem is solved by having a large number of circular grooves each of which is in the range of 30 μm to 100 μm, and each of which is provided in a plane substantially perpendicular to the axis of the oil seal.

[Action and effect]

In the present invention, the peripheral groove has a function of reducing the contact area between the lip portion and the shaft and a function of retaining an oil film in the peripheral groove, whereby a phenomenon occurring when the shaft reciprocates. The effect of preventing. Also, by providing the circumferential groove, the inner peripheral surface of the lip portion becomes uneven, and the convex portion of the inner peripheral surface comes into contact with the shaft portion with a large surface pressure. It brings about the effect of enhancing the function. The circular grooves, which are arranged in parallel in the axial direction of the oil seal and are provided in the planes substantially perpendicular to the axial line of the oil seal, are preferable from the aspect of the sealing function as compared with the spiral groove. This point will be described in detail later.

〔Example〕

 The present invention will be described below with reference to illustrated embodiments.

As shown in FIG. 1, the oil seal of this embodiment is
A seal main body 2 having a lip portion 1 formed of a rubber material is provided, and the inner peripheral surface of the lip portion 1 is fitted on a shaft (not shown) so as to be mounted on the shaft. The depth (d) (Fig. 2) of the inner peripheral surface of the lip portion 1 in contact with the shaft has a small pitch from 30 μm to 100 μm.
A peripheral groove 3 for preventing sounding is provided in the range. Reference numeral 4 in the drawing denotes a holding spring that presses the lip portion 1 toward the periphery of the shaft.

The circumferential groove is preferably a turning groove formed by turning. As the circumferential groove, a spiral groove and a large number of circular grooves arranged side by side in the axial direction of the oil seal are considered, but in terms of the sealing performance of the oil seal mounted on the reciprocating shaft. It is preferable that a large number of circular grooves are arranged side by side in the axial direction of the oil seal. That is, it can be said that the circumferential groove preferably has a spiral shape in order to facilitate the turning process. However, in the case of a spiral circumferential groove,
For example, in FIG. 1, from the position of the left end portion (a) of the region (A) of the lip portion 1 where the circumferential groove is provided to the right end portion (b).
It will be composed of a single groove that continues spirally up to the position of, and in this case, the oil that has entered the peripheral groove from its left end (a) while the shaft reciprocates passes through the right end (b) to the outside. It is not preferable in terms of hermeticity because there is a risk of leakage.

Therefore, in the present invention, the structure of the circular groove without such a defect is adopted.

Further, as can be seen from FIG. 1 in which each circular groove extends substantially at right angles to the center line extending in the axial direction of the oil seal, each circular groove has a surface substantially perpendicular to the axial line of the oil seal. It is provided inside. Therefore, it is possible to form a large number of circular grooves in the predetermined area (A) (FIG. 1). That is, when the circumferential groove is inclined at a considerable angle with respect to the axis of the oil seal,
It becomes difficult to form an appropriate number of circular circumferential grooves that do not pass through the positions of the left end portion (a) or the right end portion (b) of the area (A) in the area (A). This is because the groove inclined so as to reach the position of the left end (a) or the right end (b) does not become a circular continuous groove, but the position of the left end (a) or the right end (b). Because it will be cut off at. Such a groove, especially a groove that reaches the position of the right end (b) by sloping and ends there, may cause oil that has entered the groove to leak to the outside through the right end (b). Obviously, it is not preferable in terms of hermeticity.

When the oil seal is actually attached to the shaft, the entire region (A) does not always come into contact with the shaft. For example, when the oil pressure is high, almost the entire region (A) comes into contact with the shaft, and the high oil It is natural that only a narrow area (see (B) of FIG. 1) comes into contact with the shaft when used in a situation where no pressure acts. It is apparent from the above description that the inclined circumferential groove as described above is not particularly preferable when only the narrow region of the lip portion contacts the shaft.

The cross-sectional shape of the circumferential groove is approximately saw-tooth-shaped as shown in FIG. 2, but the shape of each tooth constituting the saw-tooth is not limited to the triangle as in the embodiment of FIG. It may be various, such as a rectangle.

The table below shows the results of experiments conducted by the inventors.

The circumferential groove 3 employed in this experiment is a spiral turning groove, and its cross-sectional shape is a sawtooth shape with each tooth being triangular as shown in FIG. In this experiment, each oil seal prepared as Samples 1 to 5 was mounted on the shaft, and a hydraulic pressure in the range of 0 to 120 kg f / cm ² was applied to the position of the space A (Fig. 1). The shaft was reciprocally slid at a stroke of ± 75 mm and a sliding speed in the range of 0 to 100 mm / sec, and the presence or absence of abnormal noise was confirmed with a sound scope. In the above table, "no groove" means a conventional oil seal having no circumferential groove, and (○) and (x) indicate that no abnormal noise is generated and that no abnormal noise is generated. It shows the state. The numbers 10 to 300 in the table indicate the depth (d) (Fig. 2) (μm) of the circumferential groove.

This experimental result shows that the depth (d) of the circumferential groove is 30 μm to 100 μm.
It shows that no abnormal noise is generated and a good result is obtained in the range of m. In this experiment, the pitch (p) of the circumferential grooves was set to about 100 μm, but this pitch itself is not closely related to the presence or absence of abnormal noise. However, if this pitch is extremely large, good results cannot be obtained, and it is preferable to set this to about 30 μm to 200 μm.

Further, whether the circumferential groove 3 is a spiral groove or a plurality of circular grooves arranged side by side in the axial direction of the oil seal is closely related to the presence or absence of abnormal noise, that is, in the above experiment. The spiral groove is adopted, while the circular groove is adopted in the present invention. However, even if the spiral groove in the above experiment is changed to the circular groove as in the present invention, it is possible to determine whether the abnormal noise occurs. Results similar to the above experimental results are obtained. However, as described above, the circular groove is preferable in terms of sealing property as compared with the spiral groove.

[Brief description of drawings]

FIG. 1 is a sectional view showing an oil seal of an embodiment of the present invention, and FIG. 2 is a view showing a shape of a circumferential groove of the oil seal. 1 ... Lip part, 2 ... Seal body, 3 ... Circumferential groove, 4 ...
... holding spring.

Claims (1)

[Scope of utility model registration request] 1. An oil seal mounted on a shaft such that the inner peripheral surface of the lip portion is fitted to a shaft that reciprocates, and a portion of the inner peripheral surface of the lip portion that contacts the shaft is prevented from sounding. A peripheral groove is provided, and the peripheral groove is arranged in parallel in the axial direction of the oil seal with a small pitch, and the depth is 30 μm to 100 μm.
And an oil seal having a plurality of circular grooves each provided in a plane substantially perpendicular to the axis of the oil seal.