JPH09133217A - Lip type seal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent lack of lubrication of a sealing sliding part so as to maintain an excellent shaft sealing function for a long time by holding a PTFE lip member and an elastomer lip member in the inner periphery of an annular metal case, which is air-tightly fitted in the inner periphery of a housing, and filling the lubricant between both the lip members. SOLUTION: A lip type seal 10 to be used for sealing a shaft 2, which is inserted into a shaft hole of the inner periphery of a housing 1 of a water pump so as to rotate a pump chamber 7 side impeller, is provided with an annular metal case 11 to be air-tightly fitted for fixation in a fitting part 1a formed with a step in the inner peripheral surface of a shaft hole of the housing 1. Furthermore, a PTFE lip member 12, of which a lip part 12a of the inner periphery to be slid for contact with the outer peripheral surface of the shaft 2 is curved and extended to the pump chamber 7 side, is provided, and an elastomer lip member 13, of which lip parts 13a, 13b to be slid for contact with the outer peripheral surface of the shaft 2 are divided to the lip member 12 side and the atmospheric air A side, is provided. The grease 14 as the lubricant is filled in a space between both the lip members 12, 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lip type seal used as a shaft sealing device such as a water pump for supplying cooling water to a turbo engine of an automobile.

[0002]

2. Description of the Related Art FIG. 4 shows an example of a water pump for circulating cooling water. This water pump is
A shaft 2 is inserted into a housing 1 through a bearing 3, and a driving force is transmitted to the shaft 2 by a pulley 4 to rotate an impeller 5 in a pump chamber 7 to supply a cooling water W. There is. The shaft 2 is axially sealed by a mechanical seal 6 at a position between the pump chamber 7 and the bearing 3 side.

The mechanical seal 6 is conventionally used as a shaft sealing device for preventing the cooling water W from flowing out to the bearing 3 side, because the cooling water W having poor lubricity is to be sealed. Therefore, for example, the mechanical seal 6
This is because if an elastomer lip-type seal such as an oil seal is adopted instead of the above, defects such as surface roughness and abnormal wear of the lip portion due to insufficient lubrication are likely to occur early, and the shaft sealing function will be significantly reduced. . On the other hand, since the mechanical seal 6 uses the carbon seal ring having excellent self-lubricating property as the sliding member, the excellent shaft sealing function can be maintained for a long period of time.

[0004]

However, in the mechanical seal 6, the stationary seal ring 6a on the housing 1 side and the rotary seal ring 6b on the impeller 5 side, which are arranged side by side in the axial direction, are attached to the shaft of the coil spring 6c. Since the structure is such that they are brought into sliding contact with each other by the urging force in the direction, the mounting space in the axial direction is larger than that of the lip type seal, and there is a problem that the demand for miniaturization of the water pump cannot be satisfied. Therefore, the technical problem of the present invention is that
As a shaft sealing device for sealing water with poor lubricity,
(EN) A lip-type seal that can be used in place of a mechanical seal is provided to reduce the mounting space of a shaft sealing device.

[0005]

As a means for effectively solving the above-mentioned technical problems, a lip type seal according to the present invention is provided on the inner circumference of an annular metal case which is tightly fitted to the inner circumference of a housing. The outer diameter portions of the PTFE lip member facing the sealing target side and the rubber-like elastic material lip member facing the atmosphere side are integrally held, and between the PTFE lip member and the elastomer lip member. It is filled with a lubricant.

Since PTFE is a fluoroethylene polymer known by the trade name of Teflon and is a material having excellent self-lubricating properties, the lip member made of this PTFE is sealed with water and other lubricating properties. Exhibits excellent sliding durability even with a scarce fluid. Also, the elastomer lip member prevents external dust from entering from the atmosphere side into the sliding portion between the PTFE lip member and the shaft. The lubricant filled between the PTFE lip member and the elastomer lip member prevents the sliding portion between the elastomer lip member and the shaft facing the atmosphere side from becoming a dry slide, and By filling the back of the PTFE lip member, it also functions as a sealant for the fluid to be sealed.

Further, in the present invention, preferably, the outer peripheral portion of the elastomer lip member reinforced by the metal ring is P
It extends in a cylindrical shape toward the TFE lip member side, and its tip is pressed against the outer peripheral back surface of the PTFE lip member. In this case, the cylindrically extending portion of the outer peripheral portion of the elastomer lip member functions as a gasket for sealing between the metal case and the PTFE lip member,
It functions as a spacer for forming a space in which the lubricant can be sufficiently filled between the elastomer lip member and the PTFE lip member.

[0008]

FIG. 1 shows a preferred embodiment of a lip type seal according to the present invention. In this figure, reference numeral 1 is a housing of a water pump that circulates the engine cooling water W, and 2 is a shaft that is inserted into a shaft hole of the inner periphery of the housing 1 and rotates an impeller on the pump chamber 7 side.

The lip type seal 10 seals the shaft 2 between the pump chamber 7 and the bearing side on the left side in the drawing, and is a stepped mounting on the inner peripheral surface of the shaft hole of the housing 1. An annular metal case 11 tightly fitted and fixed to the portion 1a,
A lip member 12 made of PTFE, which is on the inner periphery of the metal case 11 and which is slidably in contact with the outer peripheral surface of the shaft 2, is curved and extends toward the pump chamber 7 to be sealed.
The lip parts 13a and 13b, which are arranged on the inner circumference of the metal case 11 facing the atmosphere A side (opposite to the pump chamber 7) and are in sliding contact with the outer peripheral surface of the shaft 2, are made of the PTFE lip member 12. And a lip member 13 made of an elastomer formed by branching to the atmosphere A side. Between the PTFE lip member 12 and the elastomer lip member 13,
Grease 14 is filled as a lubricant.

The metal case 11 has both axial end portions 11
a and 11b are bent toward the inner diameter side.
The outer peripheral portion 12b of the PTFE lip member 12 and the outer peripheral portion 13c of the elastomer lip member 13 are integrally held in a state of being sandwiched from both sides in the axial direction. Metal ring 13d
The outer peripheral portion 13c of the elastomer lip member 13 reinforced by the cross-section has a substantially L-shaped cross-section that extends cylindrically toward the PTFE lip member 12 side, and the tip portion thereof is made of PTFE.
It is pressed against the back surface of the outer peripheral portion 12b of the lip-making member 12.

Since the grease 14 has an appropriate viscosity, it does not easily flow out to the pump chamber 7 or the atmosphere A side, and the lip portion 12a of the PTFE lip member 12 and the lip portion 13a of the elastomer lip member 13 are Thirteen
A lubricating film is formed by intervening in the sliding portion between b and the shaft 2. Further, the grease 14 itself has a function as a sealant that effectively prevents the cooling water W from leaking. Therefore, although the engine cooling water W having poor lubricity is targeted for sealing, the lip portion 12a,
Surface roughness and abnormal wear of 13a and 13b are unlikely to occur, and excellent sealing performance can be expected for a long period of time. Further, since this lip-type seal 10 is formed by arranging two lip members 12 and 13 which are thin in the axial direction, the mounting space is shortened in the axial direction as compared with the mechanical seal 6 shown in FIG. To be done.

When an impeller (not shown) in the pump chamber 7 rotates via the shaft 2, the pressure in the vicinity of the inner periphery of the impeller of the pump chamber 7, that is, in the vicinity of the lip type seal 10, becomes relatively low, so that the pump chamber The PTFE lip member 12 facing 7 does not receive a large load due to the pressure of the cooling water W to be sealed, but the PTFE lip member 1
In order to prevent the lip portion 12a from sticking to the outer peripheral surface of the shaft 2 due to the restoring force of 2 itself, as shown in another embodiment in FIG. 2, the back surface of the PTFE lip member 12 is provided with a metal backup ring. It is also preferable to have a configuration of backing up by 15. Further, a gasket means such as an O-ring is interposed between the inner peripheral surface of the shaft hole of the housing 1 and the tight fitting portion of the metal case 1 as required.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 3 shows a lip type seal 10 according to the present invention.
The results of the sealing performance test of a comparative example composed of a single elastomer lip member under the following conditions are shown. The horizontal axis represents the operating time and the vertical axis represents the cumulative leak amount. Test conditions Shaft speed: 6500 rpm Pressure: 2 kg / cm ² Temperature: 100 ° C Sealing target fluid: Water

As is clear from the above test results, since the comparative example is made of an elastomer lip member, it exhibits excellent sealing characteristics at the initial stage, but lacks lubrication due to the water to be sealed being poorly lubricated. When it occurs and wears at an early stage and the operating time exceeds 100 hours, the leakage amount is remarkably increased. On the other hand, in the case of the lip-type seal of the present invention, it was confirmed that the lubricity of the sliding portion is improved by the grease, so that good sealing performance is maintained for a long period of time.

[0015]

EFFECTS OF THE INVENTION The lip-type seal of the present invention prevents an insufficient lubrication of the sealing sliding portion and maintains an excellent shaft-sealing function for a long period of time even when water having poor lubricity is to be sealed. Therefore, it is possible to reduce the mounting space of the shaft sealing device and to reduce the size of equipment such as a pump by using water, which has poor lubricity, in place of the mechanical seal to be sealed.

[Brief description of the drawings]

FIG. 1 is a half sectional view showing a preferred embodiment of a lip-type seal according to the present invention by cutting along a plane passing through an axis thereof.

FIG. 2 is a half sectional view showing another preferred embodiment of the lip-type seal according to the present invention by cutting along a plane passing through the axis thereof.

FIG. 3 is an explanatory diagram showing a sealing performance test result.

FIG. 4 is a cross-sectional view showing a water pump equipped with a mechanical seal as a shaft sealing device, taken along a plane passing through the axis thereof.

[Explanation of symbols]

 1 Housing 2 Shaft 10 Lip Type Seal 11 Metal Case 12 PTFE Lip Member 13 Elastomer Lip Member 14 Grease (Lubricant)

Claims (2)

[Claims] 1. An outer diameter portion of each of a PTFE lip member facing the sealing target side and an elastomer lip member facing the atmosphere side is integrally formed on the inner circumference of an annular metal case closely fitted to the inner circumference of the housing. And a lubricant is filled between the PTFE lip member and the elastomer lip member. 2. The outer peripheral portion of the elastomer lip member reinforced by a metal ring extends cylindrically toward the PTFE lip member side, and the tip portion thereof is the outer periphery of the PTFE lip member according to claim 1. A lip type seal characterized by being pressed against the back of the part.