JPH0225983Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to improvements in lip seals for sealing the rotating shafts of various types of equipment.

[Conventional technology]

BACKGROUND ART Conventionally, a lip seal shown in FIG. 7 has been widely known as a lip seal used in various devices such as a compressor for a car cooler.

That is, the lip seal, which is generally designated by the reference numeral 21 in the figure, is an annular lip seal that is airtightly fitted into a step 24 formed in the shaft hole 23 of the equipment housing 22 via an O-ring 25 and fixed by a snap ring 26. A metal case 27, a rubber gasket 28 fitted to the case 27, and the case 27.
The outer diameter portion is airtightly clamped by a retainer 29 having a substantially L-shaped cross section which is caulked and fixed to the inner surface of the annular sheet 30 mainly made of tetrafluoroethylene resin. A rotating shaft 3 whose inner diameter portion is loosely inserted into the shaft hole 28 of the housing 22.
The sealed fluid A is sealed by slidingly contacting the outer circumferential surface 31' of No. 1 with an appropriate interference margin while being bent and deformed in the axial direction so as to protrude toward the sealed fluid A side.

[Problem that the invention attempts to solve]

However, this type of conventional lip seal 2
1 is a seat 30 supported between the case 27 and the retainer 29 so as to extend in the radial direction.
As mentioned above, the inner diameter side of the case 27 and the retainer 29 are suddenly bent and deformed in the axial direction, that is, in the direction of 90° with respect to the outer diameter part,
Since the deformation is forcibly performed by preforming, a large residual stress is generated, and therefore the surface pressure at the sliding contact portion 32 between the sheet 30 and the rotating shaft 31 is
It becomes large in the side vicinity part 33. For this reason, wear of the sheet 30 increases locally in the portion 33, leading to early deterioration of sealing performance. Furthermore, as described above, since the maximum surface pressure part is biased toward the vicinity part 33 on the atmosphere B side, the moment about the bending part 34 causes the tip part 35 of the sheet 30 on the sealed fluid A side to move toward the rotating shaft 31. Outer surface 31'
As a result, the sealed fluid A is likely to enter the sliding contact portion 32 like a wedge from the separated portion, resulting in leakage.

[Means for solving problems]

The lip seal of the present invention was developed in view of the above problems, and consists of an annular metal case that is hermetically fitted to the inner periphery of the shaft hole of the device housing, and an outer diameter portion that is hermetically fitted to the case. The lip seal consists of a fixed annular resin sheet, and the inner diameter axial portion of the sheet, which extends in a curved or bent manner toward the sealed fluid side, slides into contact with the outer circumferential surface of the rotating shaft with an appropriate interference margin. A tip portion is formed at the end portion of the axial portion on the sealed fluid side, the inner diameter edge of which protrudes at an acute angle with respect to the outer circumferential surface of the rotating shaft.

[Effect]

According to the above configuration, the self-sealing effect due to the pressure of the sealed fluid is increased, that is, the pressure of the sealed fluid applied to the acute-angled pointed end presses the pointed end in the inner radial direction, and the inner circumferential surface of the pointed end is pressed. Sealing performance is improved because it comes into close sliding contact with the outer circumferential surface of the rotating shaft, and there is no separation like in the conventional case. In addition, for the above reason, the inner circumferential surface of the axially protruding portion of the inner diameter of the seat is in sliding contact with the outer circumferential surface of the rotating shaft over the entire surface, which alleviates local increases in surface pressure and reduces the amount of wear. be done.

〔Example〕

Hereinafter, the specific structure and operation of the lip seal of the present invention will be explained based on the embodiments shown in FIGS. 1 to 6.

First, FIG. 1 shows a state in which a lip seal 1 according to the first embodiment is installed.
An annular metal case 7 that is airtightly fitted via an O-ring 5 and fixed by a snap spring 6.
The outer diameter portion 10a, which expands in the radial direction, is airtightly held by the rubber gasket 8 fitted to the case 7 and the retainer 9, which has a substantially L-shaped cross section and is caulked and fixed to the inner surface of the case 7. It consists of an annular sheet 10 whose main material is tetrafluoroethylene resin. The seat 10 extends in the axial direction with the inner diameter side of the case 7 and the retainer 9 bent toward the sealed fluid A side (hereinafter referred to as an axial portion 10b), and the inner circumferential surface 10' of the seat 10 extends freely into the shaft hole 3. It is in sliding contact with the outer circumferential surface 11' of the inserted rotating shaft 11 with an appropriate interference. Further, a groove 12 having a substantially V-shaped cross section is provided around the end of the axial portion 10b on the side of the sealed fluid A, and as shown in an enlarged view in FIG. Both tapered surfaces 12a, 1
2b, the inner diameter side tapered surface 12a is connected to the rotating shaft 1.
A pointed end 13 is formed with an inner diameter edge protruding at an angle θ (θ=30°) with respect to the outer circumferential surface 11' of the second embodiment.

According to this embodiment, the rigidity of the tip 13 of the seat 10 is weakened by the groove 12, and the sealing fluid A is applied perpendicularly to the inner diameter side tapered surface 12b.
The pressure acts on the pointed end 13 in the inner radial direction, so that the inner circumferential surface 13' of the pointed end 13
is in close sliding contact with the outer circumferential surface 11' of the rotating shaft 11 with an appropriate surface pressure, thereby preventing the sealed fluid A from entering. Moreover, as a result, as shown in FIG. 1, the seat 10 is
is the outer circumferential surface 11' of the rotating shaft 11 over the entire surface.
Therefore, the sealing performance is improved, and the local increase in surface pressure in the vicinity of the bent portion 10c is alleviated, so that wear is suppressed.

Fig. 3 is a graph showing the results of a comparative test of the amount of leakage between this example and a conventional product under the following conditions, and Fig. 4 is an explanation showing the results of a seat wear test under the same conditions. In the figure, these test results clearly show the improvement in sealing performance and durability according to this example.

<Conditions> Rotation speed = 2000 rpm Pressure = 2 Kg/cm ²・G Temperature = 10°C Operating time = 300 Hrs Sealing fluid = Suniso 5GS oil + Freon 12 Next, Figure 5 shows the second embodiment of the present invention. As such, a groove 14 having a substantially U-shaped cross section is provided around the end of the axial portion 10b of the seat 10 on the sealed fluid A side. The inner diameter tapered surface 14b constitutes the inner diameter pointed end 13, and FIG. 6 shows a third embodiment in which a single tapered surface 15 is formed at the end of the inner diameter axial portion 10b of the seat 10. The pointed end portion 13 is constructed as shown in FIG.

Note that the tapered surface 12b in each of the above embodiments,
14b and 15, the smaller the angle θ, the more remarkable the above effect becomes.For example, in the first embodiment, the angle θ was set to 30°, but it goes without saying that the present invention is not limited to this. .

[Effect of idea]

As detailed above, the lipstick of the present invention has the following features:
By providing a tip with a sharply protruding inner edge around the inner axial portion of the seat, the self-sealing effect due to the pressure of the internal fluid is increased, and the axial end is prevented from lifting off the outer circumferential surface of the rotating shaft. As a result, the sliding surface becomes larger and the sealing performance improves, and the local increase in surface pressure on the sliding surface is alleviated, which suppresses wear and improves durability. It has practical value.

[Brief explanation of drawings]

Fig. 1 is a half-cut sectional view showing the first embodiment of the lip seal of the present invention, Fig. 2 is an enlarged sectional view of the same main part, Fig. 3 is a graph showing the leak test results, and Fig. 4 shows the wear test results. The explanatory drawings, FIGS. 5 and 6 are enlarged sectional views of main parts showing other embodiments of the present invention, and FIG. 7 is a half-cut sectional view showing an example of a conventional lip seal. 1... Lip seal, 2... Housing, 3... Shaft hole, 7... Case, 9... Retainer, 10... Seat,
11... Rotating shaft, 12a, 12b, 14a, 14
b, 15... Tapered surface, A... Enclosed fluid.

Claims (1)

[Scope of utility model registration request] It consists of an annular metal case that is hermetically fitted to the inner periphery of the shaft hole of the equipment housing, and an annular resin sheet whose outer diameter is hermetically fixed to the case, and curves toward the sealed fluid side. Alternatively, in a lip seal in which the inner diameter axial portion of the sheet extends in a bent manner and slides into sliding contact with the outer peripheral surface of the rotating shaft with an appropriate interference, the inner diameter edge is placed at the end of the axial portion on the sealed fluid side. A lip seal characterized by having a pointed end formed at an acute angle and protruding from the outer peripheral surface of the shaft.