JPH0861512A - Oil seal - Google Patents

Abstract

PURPOSE: To enhance the dust shutoff performance of dust lips of an oil seal mounted on a shaft while a certain tightening margin is reserved and also prevent breakage of the dust lips resulting from seizure or generation of negative pressure between lips during operation. CONSTITUTION: Dust lips 6 are furnished on an oil seal 1 mounted on a shaft 7 Awhile a certain tightening margin is reserved, and a number of projections 12 (contacting parts) and bottoms 13 (non-contact parts) are alternately provided at a certain spacing over the whole circumference of the sliding part of the dust lip 6 with the shaft 7. The projections 12 provided over the whole circumference contact tightly with the shaft, to enhance the dust shutoff performance, and no negative pressure is generated between the lips because a draughtiness is secured between the bottoms 13 and the shaft 7, and also the dust lips can be prevented from breakage resulting from seizure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil seal used for an engine cam of an internal combustion engine, a crankshaft, or a sealing portion of various devices.

[0002]

2. Description of the Related Art In a conventional oil seal for an engine cam or a crankshaft in an internal combustion engine, a main lip 31 and a dust lip 33 of the oil seal 30 have a tightening margin as shown in FIG. Although mounted on the shaft 34, when the main lip 31 and the dust lip 33 are thus mounted on the shaft 34 with a tight margin, a spiral groove formed on the inner peripheral surface of the main lip 31. 32
Negative pressure is generated in the chamber 35 formed between the main lip 31 of the oil seal 30 and the dust lip 33, and the pressure difference from the atmospheric side causes the main lip 31 to wear and reduce the durability. There is a fear.

The die slip 3 of the oil seal 30
The lubrication of No. 3 is performed by the grease filled in the chamber 35 between the main lip 31 and the dust lip 33, but the dust lip 33 causes poor lubrication at high peripheral speed,
Not only does seizure generate heat and wear, but the dust lip 33 may be damaged when the shaft 34 is eccentric.

As one means for solving the above problems, when the oil seal 30 is mounted on the shaft 34, the shaft 34
It has also been attempted to bring the tip and the tip 33a of the dust lip 33 apart from each other by leaving a small gap h therebetween. However, when the tip 33a of the shaft 34 and the dust lip 33 is brought into the non-contact state as described above, Negative pressure is not generated in the chamber 35 formed between the main lip 31 and the dust lip 33, and therefore there is no fear of wear of the main lip, but the shaft 34 and the dust lip 33 do not come into contact with each other. Therefore, the problem of inferior dust sealing performance was unavoidable.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and even if the main lip and dust lip of the oil seal are mounted on the shaft with a predetermined tightening margin, The purpose of the present invention is to provide an oil seal having excellent durability without generating a negative pressure in the chamber between the dust lip.

[0006]

In order to achieve the above object, an oil seal according to the present invention is an oil seal in which a main lip and a dust lip are mounted on a shaft with a tightening allowance. It is characterized in that a large number of contacting portions and non-contacting portions with respect to the shaft are alternately formed at predetermined intervals over the entire circumference of the sliding portion.

[0007]

In the oil seal according to the present invention, the contact portion and the non-contact portion with respect to the shaft are alternately arranged at predetermined intervals over the entire circumference of the tip portion of the dust lip of the oil seal mounted on the shaft with a tightening margin. Since a large number of dust strips are provided, the contact portions at predetermined intervals are in sliding contact with the shaft, and there is a non-contact portion between the contact portions and the contact portions. Since it has air permeability without contact, the chamber formed by the main lip and the dust lip does not become negative pressure, and it is possible to prevent abnormal noise and dust lip damage due to poor lubrication of the dust lip. it can.

[0008]

EXAMPLE An example of the present invention will be described with reference to FIG.
In FIG. 1, reference numeral 1 denotes an oil seal made of an elastic material such as synthetic rubber. The oil seal 1 includes an annular peripheral wall 3 attached to a housing on the outer periphery of a metal reinforcing ring 2 having an L-shaped cross section, and the peripheral wall 3 A main lip 5 that extends axially through a base portion 4 that extends further inward and that protrudes toward the inner circumference of the oil chamber is formed integrally with a dust lip 6 that protrudes toward the atmosphere side from the base portion 4. Further, 8 is a spring mounted on a spring holding portion 9 provided on the back surface of the main lip 5 of the oil seal 1 described above, and the spring 8 applies a required tightening force to the main lip 5, and 10 is mentioned above. It is a spiral groove engraved on the inner peripheral side of the main lip 5. The oil seal 1 is configured to fit the annular peripheral wall 3 into a housing (not shown), and bring the main lip 5 and the dust lip 6 into contact with the shaft 7 with a predetermined tightening allowance for sealing.

Projections 12 and valleys 13 are alternately formed at predetermined intervals over the entire circumference of the sliding portion of the dust lip 6 with the shaft 7. Therefore, the contact state between the dust lip 6 and the shaft 7 is such that the protrusions 12, 12, ... Contact the shaft 7, and the valleys 13, 13, 13 ,.
Is not in contact with. In this way, when the dust lip 6 of the oil seal 1 of this embodiment is mounted on the shaft 7, the sliding portion of the dust lip 6 is alternately formed with the contact portion and the non-contact portion with the shaft 7. Will be.

In the embodiment shown in FIG. 1, as described above, the projections 12, 12, 12, ... And the valleys 13, are formed over the entire circumference of the sliding portion of the dust lip 6 with the shaft 7. 13, 13,
, And are alternately provided at a predetermined interval, when the main lip 5 and the dust lip 6 of the oil seal 1 are mounted on the shaft 7 with a required tightening margin, the dust lip 6 , Are in contact with the shaft 7, but are not in contact with the shaft 7, so that the main lip 5 and the dust lip 6 are not in contact with each other. The formed chamber 15 and the atmosphere side have the above-mentioned valleys 13, 13, ...
Since air is vented through the chamber 1, even if the suction action is exerted by the action of the spiral groove 10 formed on the inner peripheral surface of the main lip 5 with the rotation of the shaft during operation of the engine, the chamber 1
5 does not have a negative pressure, so that the main lip 5 is not worn, and the protrusions 12, 12, ...
.. can prevent dust from the atmosphere side, and the existence of the valleys 13 can prevent sticky slip of the dust lip 6 or generation of abnormal noise and burning of the dust lip 6 due to sliding heat generation. is there.

The shapes of the contact portion and non-contact portion between the dust lip 6 and the shaft 7 and the non-contact portion are not limited to the protrusion 12 and the valley 13 shown in FIG. 1. For example, as shown in FIG. A large number of notch recesses 14, 14, 14, ... Are formed at predetermined intervals over the entire circumference with the tip portion 6a of the dust lip 6 as a contact portion, and these notch recesses 14, 14, 14 ,. They may be non-contact parts, and their shape, size, number and spacing are free. In short, when the dust lip 6 and the shaft 7 are in contact with each other, it is desirable that the contact portion and the non-contact portion are alternately formed with the shaft 7 over the entire circumference of the sliding portion of the dust lip 6.

[0012]

The oil seal according to the present invention is an oil seal in which the main lip and the dust lip are mounted on the shaft with a tightening allowance, at predetermined intervals over the entire circumference of the sliding portion of the dust lip. Since a large number of contact portions and non-contact portions with respect to the shaft are alternately formed, dust from the atmosphere side can be blocked by the contact portions, and the presence of the non-contact portions causes the chamber formed by the main lip and the dust lip. Since the air and the atmosphere side can be provided with air permeability, generation of negative pressure in the chamber during operation and damage due to seizure of the dust lip due to poor lubrication can be prevented.

[Brief description of drawings]

FIG. 1 is a partial vertical sectional view showing an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of another embodiment of the present invention.

FIG. 3 is an explanatory view of a conventional oil seal.

FIG. 4 is an explanatory view of a conventional example in which the inner diameter of the dust lip is larger than the shaft diameter.

[Explanation of symbols]

 1 oil seal 5 main lip 6 dust lip 7 shaft 12 protrusion (contact part) 13 valley (non-contact part) 15 chambers

Claims (3)

[Claims] 1. An oil seal in which a main lip and a dust lip are attached to a shaft with a tightening allowance, and a contact portion with respect to the shaft at a predetermined interval over the entire circumference of the sliding portion of the dust lip with the shaft. An oil seal having a large number of alternating non-contact portions. 2. The oil seal according to claim 1, wherein the contact portion and the non-contact portion of the sliding portion with respect to the dust lip shaft are a protrusion and a valley. 3. The oil seal according to claim 1, wherein the contact portion and the non-contact portion of the sliding portion with respect to the shaft of the dust lip are a tip portion and a notched concave portion formed at the tip portion.