JPS6237023Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an oil seal with a back-up spring.

When sealing a liquid with a large pressure change in a device with a rotating shaft protruding from the housing, a back-up spring is used to prevent the liquid from leaking from the part where the rotating shaft protrudes from the housing, that is, the sealed part. A equipped oil seal is used. A conventional example of this type of oil seal is, for example, as shown in Japanese Patent Publication No. 57-8338, in which a part of a two-part metal ring having a U-shaped cross section is used as a back-up spring. One of the two parts forming this metal ring is coated with adhesive over its entire surface, and the seal main body with the lip is baked during molding, while the other part has only the lip and its surrounding area coated with adhesive. Some products are made in a non-adhesive state and have a back-up spring effect to release them from the surface. However, without adhesive treatment, the metal ring on the side where the back-up spring acts must be cut into a shape that matches the inner circumferential surface of the oil seal's lip neck, and this processing work is complicated and requires molding. There is a disadvantage that the rubber flows out as burrs on the inner circumferential surface of the back-up spring due to the pressure at the time. Also, conventional examples, for example,
As shown in No. 15919, an oil seal has been devised in which a back-up spring is attached after the oil seal is molded, but such attachment reduces productivity and also causes damage to the inner circumferential surface of the lip neck. The drawback is that the back spring does not have a good fit and is not durable. Furthermore, during pressurization, the back-up spring is pressed against the rotating rotating shaft, and the back-up spring may rotate together with the shaft. This results in damage to the oil seal.

The object of the present invention is to provide an oil seal with a back-up spring that solves the above-mentioned drawbacks of the conventional oil seal.

2 is a sectional view of the first embodiment of the present invention, FIG. 4 is a sectional view of the second embodiment, and FIG. 1 shows the embodiment of FIG. 2 attached to the main body of the device.

As shown in Fig. 1, the oil seal 1 of the present invention is made of a synthetic resin such as polytetrafluoroethylene or polyamide, which is difficult to deform due to the pressure and temperature during molding, that is, has a high heat distortion temperature. The back-up spring 2 is inserted into the cavity of the molding die during molding of the oil seal 1, and is non-adhered into the gap formed between the inner peripheral surface of the lip-neck portion 6 and the radial portion 41 of the reinforcing ring 4. Some are still installed. That is, in FIG. 1, the oil seal 1 except for the tip of the radial portion 41 of the reinforcing ring 4 has the seal body 7 vulcanized and bonded during molding, and the seal lip portion 5 extends from the seal body 7 via the lip neck portion 6. It's out. A lip edge 8 formed at the tip of the seal lip portion 5
is in sliding contact with the rotating shaft 10 to prevent the liquid within the housing 3 from leaking.

In the embodiment shown in FIGS. 2 and 3, the inner peripheral surface of the lip neck portion 6 and the radial portion 4 of the reinforcing ring 4 are
A back-up spring 2 is housed in the gap formed between the back-up spring 2 and the oil seal. 61 is provided, and the protrusion 21 of the back-up spring 2 is inserted into and engaged with the protrusion 21.

When the oil seal 1 of the present invention fitted into the housing 3 of the machine body is in contact with the rotating shaft 10 as shown in FIG. The back-up spring 2 is in a state where it can be freely released without contacting it, and the back-up spring 2 is not separated from the seal body 7 and is pulled by the rotating shaft 10 and does not rotate together.

Therefore, the seal lip 5 easily follows the rotating shaft 10 and has good sealing performance. In addition, even if the pressure of the sealing fluid is high, the presence of the back-up spring 2 makes it difficult for the seal lip to deform.
There is no possibility that the area in contact with the rotating shaft 10 will be abnormally expanded. This prevents abnormal wear of the oil seal.

In another embodiment of the present invention shown in FIGS. 4 and 5, a plurality of protrusions 21 provided on the side surface of the back-up spring 2 are fitted into the recesses of the radial portion 41 of the reinforcing ring 4. Similarly to the embodiment described above, it is possible to prevent the backup spring 2 from rotating together with the rotating shaft 10. Furthermore, the radial portion 41 of the reinforcing ring 4 may have a notch instead of a recess.

As mentioned above, the back-up spring 2 is attached to the oil seal 1 during molding, so even if the back-up spring 2 is not precisely machined, the back-up spring 2 inserted into the molding die can be
Since the pressure at the time of molding causes it to adhere tightly to the middle mold, the inner circumferential surface of the lip neck part 6 and the diameter of the reinforcing ring 4 are in a stable state without rubber flowing out as burrs on the inner circumferential surface of the back-up spring 2. The back-up spring 2 is attached to the rotating shaft 10 in a non-adhesive state in the gap formed between the back-up spring 2 and the rotating shaft 10.
Even if they come into contact with each other, the backup spring 2 will not rotate together with the rotating shaft, and damage to the oil seal 1 can be avoided. Therefore, even for sealing fluids with large pressure changes, the seal lip 5
deformation is less likely to occur, the back-up spring 2 does not rotate together, and the oil seal 1 has good pressure resistance and smooth followability.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the pressure-resistant seal device of the present invention in use, Fig. 2 is a cross-sectional view of the pressure-resistant seal device of the present invention, and Fig. 3 is a back-up spring used in the pressure-resistant seal device of Fig. 2. 4 is a sectional view of another embodiment of the pressure sealing device of the present invention, and FIG. 5 is a partial plan view of a back-up spring used in the embodiment of FIG. 4. DESCRIPTION OF SYMBOLS 1... Oil seal, 2... Backup spring, 21... Protrusion, 4... Reinforcement ring, 41... Radial direction part, 6... Lip neck part, 61... Recessed part.

Claims (1)

[Scope of utility model registration request] It includes a synthetic resin back-up spring 2 that is installed in a non-adhesive state in a gap formed between the inner circumferential surface of the lip neck portion 6 and the radial portion 41 of the reinforcing ring 4 during oil seal molding. A pressure-resistant seal device characterized in that a projection 21 is provided on the back-up ring, and the projection 21 is engaged with the lip-neck portion 6 or the radial portion 41 of the reinforcing ring 4 to prevent the back-up ring from rotating together.