JP2008180244A - Sealing device for water pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve sealing performance and wear resistance of a sealing device 1 for a water pump that is mounted between a housing 2 and a shaft 3 so that sealed fluid such as LLC will not leak from the inner side A to the outer side B. <P>SOLUTION: The sealing device 1 includes a first seal lip 14 secured to the housing 2 and slidably making close contact with the shaft 3 or a sleeve fixed to the shaft 3, a second seal lip 24 disposed on the outer side B of the first seal lip 14, a rotary body 41 disposed in a space 4 between the seal lips 14, 24 and secured to the shaft 3 rotatably therewith, and a pumping mechanism 42 provided on the rotary body 41 and performing such return pump function as to return the sealed fluid having entered the space 4 through the first seal lip 14 to the inner side A. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sealing device according to a sealing technique, and more particularly to a sealing device suitable for use in a shaft seal portion of a water pump. The sealing device of the present invention is used for, for example, a water pump for cooling an automobile engine, or used for other cooling water pumps.

  Conventionally, a sealing device 51 shown in FIG. 5 is known as a sealing device used in this type of water pump, and this sealing device 51 is fixed to a housing 52 and seals slidably in contact with a shaft 53. By arranging a plurality of lips 54 side by side, a sealing fluid such as LLC is sealed so as not to leak from the inside A to the outside B.

However, according to the above prior art, the sealing operation which is the main function depends solely on the sliding operation of each seal lip 54, and therefore there is a limit to the sealing performance that can be exhibited. In addition to sealing performance, it is necessary to pay attention to the following points as a sealing device for a water pump.
(1) Since a pressure of about 0.2 MPa acts from the inside as the sealing fluid pressure, it is necessary to consider pressure resistance.
(2) Since the seal lip is easily worn by water lubrication, it is necessary to consider wear resistance.
(3) Since foreign matters such as cast sand, rust, or sand particles existing in the pump are mixed in the water and easily wear the seal lip, it is necessary to consider wear resistance also in this respect.

JP 2002-310095 A

  In view of the above, the present invention has an object to provide a sealing device capable of improving its sealing performance and wear resistance in a sealing device for a water pump that seals a sealing fluid such as LLC. .

  To achieve the above object, a sealing device according to claim 1 of the present invention is a water pump sealing device mounted between a housing and a shaft so that a sealing fluid such as LLC does not leak from the inside of the machine to the outside of the machine. A first seal lip that is slidably in close contact with the shaft or a sleeve fixed to the shaft, a second seal lip disposed outside the machine of the first seal lip, and between the two seal lips A rotating body that is disposed in the space and is fixed to the shaft and rotates together with the shaft, and a sealing fluid that is provided in the rotating body and passes through the first seal lip and enters the space is returned to the inside of the machine. And a pumping mechanism that exhibits a return pumping action.

  The sealing device according to claim 2 of the present invention is a water pump sealing device mounted between the housing and the shaft so that a sealing fluid such as LLC does not leak from the inside of the machine to the outside of the machine, and is fixed to the inner periphery of the housing. A first sealing lip that is integrally formed with a flange portion inwardly in a machine-direction end of a cylindrical fixing portion to be slidably in contact with the shaft or a sleeve fixed to the shaft. The first lip seal member formed integrally with the flange portion is integrated radially inward with the outer end of the tubular fixing portion fixed to the inner periphery of the cylindrical fixing portion of the first lip seal member. A second lip seal member molded and integrally formed with a second seal lip that is slidably in close contact with the shaft on the flange, and the first lip seal member on the outside of the second lip seal member. A backup ring that is fixed to the inner periphery of the fixed part and prevents excessive deformation of the second seal lip, and a rotating body that is disposed in the space between the two seal lips and that is fixed to the shaft and rotates together with the shaft And a pumping mechanism that is provided in the rotating body and exhibits a return pumping action so as to return the sealed fluid that has passed through the first seal lip and entered the space to the inside of the apparatus.

  According to a third aspect of the present invention, there is provided the sealing device for a water pump according to the second aspect, wherein the pumping mechanism is provided on the outer peripheral surface of the rotating body and is located on the outer peripheral side. It faces the inner peripheral surface of the cylindrical fixing portion of the member with a slight radial gap.

  Furthermore, the sealing device according to claim 4 of the present invention is the water pump sealing device according to claim 2 described above, wherein the inner end face of the rotating body when the first seal lip is deformed by being pressed by the sealing fluid pressure. The first lip seal member is provided with an abutment protrusion that abuts on and away from each other and suppresses excessive deformation of the first seal lip.

  In the sealing device according to the first aspect of the present invention having the above-described configuration, the first and second seal lips are arranged side by side in the axial direction, and a rotating body is arranged in a space between both seal lips. Since the pumping mechanism is provided, when the shaft rotates and the rotating body is driven to rotate, a return fluid pressure is generated by the rotating pumping mechanism, thereby returning the fluid in the space to the inside of the machine. The effect is demonstrated. Therefore, even if there is a sealing fluid that passes through the first seal lip on the inside of the machine and enters the space, it can be returned to the inside of the machine, and this sealing fluid reaches the second seal lip on the outside of the machine. Can be delayed. Therefore, it is possible to effectively prevent the sealing fluid such as LLC from leaking from the inside of the pump machine to the outside of the machine and improve the sealing performance.

  In addition, when the shaft rotates and the rotating body is driven to rotate, a return fluid pressure is generated by the pumping mechanism in the space. Therefore, both the first seal lip on the inner side and the second seal lip on the outer side have an acting load. This reduces the contact surface pressure against the shaft. If the contact surface pressure is reduced, even if foreign matter such as casting sand is caught in the lip sliding portion, the damage received can be reduced. Therefore, it is possible to suppress early wear of the seal lip and improve wear resistance.

  Further, in the sealing device according to claim 2 of the present invention having the above-described configuration, the same function and effect as those of claim 1 are exhibited, and excessive deformation of the second seal lip on the outside of the machine is suppressed by the backup ring. Therefore, it is possible to stabilize the posture of the second seal lip. If the posture of the seal lip is stabilized, the seal lip cannot be strongly pressed against the shaft, so that the sealing performance and the wear resistance can be remarkably improved. Therefore, with the above configuration, the sealing performance and wear resistance of the second seal lip on the outside of the machine can be further improved. In addition, since the second lip seal member and the backup ring are fixed together on the inner periphery of the cylindrical fixing portion of the first lip seal member, positioning of the parts is easy and the assembly workability is excellent. Yes.

  In addition to this, in the sealing device according to claim 3 of the present invention, the pumping mechanism is provided on the outer peripheral surface of the rotating body, and the inner periphery of the cylindrical fixing portion of the second lip seal member located on the outer peripheral side thereof. Since it faces the surface with a slight radial gap, a kind of labyrinth portion is set in this gap, and thus a relatively large return fluid pressure is generated in this gap. Therefore, the return pump action by the pumping mechanism can be made strong.

  Furthermore, in the sealing device according to claim 4 of the present invention, when the first seal lip inside the machine is deformed by being pressed by the sealing fluid pressure, the first seal lip is brought into contact with and separated from the machine inner end face of the rotating body. Since the contact protrusion that suppresses excessive deformation of the seal lip is provided on the first lip seal member, excessive deformation of the first seal lip can be suppressed by the contact protrusion and the posture can be stabilized. It is possible. As described above, since the seal lip cannot be strongly pressed against the shaft if its posture is stabilized, both the sealing performance and the wear resistance can be remarkably improved. Therefore, with the above configuration, the sealing performance and wear resistance of the first seal lip inside the machine can be further improved.

  Next, embodiments of the present invention will be described with reference to the drawings.

First embodiment ...
FIG. 1 shows a cross section of a main part of a sealing device 1 according to a first embodiment of the present invention. The sealing device 1 according to the embodiment includes a water pump for cooling an automobile engine so that LLC (long life coolant) as a sealing fluid (liquid) does not leak from the inside (sealing fluid side) A to the outside (atmosphere side) B. And is configured as follows.

  That is, first, a first seal lip 14 fixed to the inner periphery of the shaft hole of the housing 2 and slidably in close contact with the peripheral surface of the shaft 3 is provided. Two seal lips 24 are provided. The second seal lip 24 is also fixed to the housing 2 and is slidably in close contact with the peripheral surface of the shaft 3. An annular space 4 is provided between the first and second seal lips 14, 24, and a rotating body 41 is disposed in the space 4. The rotating body 41 has a ring shape, is fixed to the shaft 3 and rotates together with the shaft 3, and a sealing fluid that has entered the space 4 through the first seal lip 14 is passed to the inner side A of the outer peripheral surface thereof. A pumping mechanism 42 that exhibits a return pumping action is provided so that the pumping mechanism 42 returns to the center. Specifically, the pumping mechanism 42 includes a plurality of pumping screw grooves 43 that are inclined with respect to the central axis 0. In FIG. 1, for the convenience of drawing, only the rotating body 41 and the pumping mechanism 42 (screw groove 43) are shown in appearance.

  Moreover, the sealing device 1 according to the embodiment includes a first lip seal member 11, a second lip seal member 21, a backup ring 31, and a rotating body 41 as its components.

  Among these, the first lip seal member 11 is integrally formed with a flange portion 13 radially inwardly at the inner end portion of the cylindrical fixing portion 12 fixed to the inner periphery of the shaft hole of the housing 2. A first seal lip 14 that is slidably in close contact with the peripheral surface of the shaft 3 is formed integrally with the portion 13. The first lip seal member 11 is formed by attaching a rubber-like elastic body 16 to a metal ring 15 in which a flange portion 15b is integrally formed radially inwardly at an inner end of the cylindrical portion 15a (vulcanization adhesion). The rubber-like elastic body 16 causes the end-face rubber portion 16a attached to the machine-side end surface of the cylindrical portion 15a of the metal ring 15 and the outer peripheral surface of the cylindrical portion 15a of the metal ring 15 to be The outer peripheral rubber portion 16b that is attached, the flange rubber portion 16c that is attached to the machine inner end surface and the inner peripheral portion of the flange portion 15b of the metal ring 15, and the first that is disposed on the inner peripheral side of the flange rubber portion 16c. The seal lip 14 is integrally formed. The end rubber portion 16 a and the outer peripheral rubber portion 16 b form the tubular fixing portion 12 together with the tubular portion 15 a of the metal ring 15. The flange rubber portion 16 c forms the flange portion 13 together with the flange portion 15 b of the metal ring 15. The first seal lip 14 is configured to be pressed against the peripheral surface of the shaft 3 when the pressure-receiving surface 14a is directed toward the machine inner side A and when the pressure-receiving surface 14a receives a sealing fluid pressure.

  The second lip seal member 21 is integrated with a flange portion 23 radially inward at the outer end of the tubular fixing portion 22 fixed to the inner periphery of the cylindrical fixing portion 12 of the first lip seal member 11. A second seal lip 24 that is molded and is slidably in close contact with the peripheral surface of the shaft 3 is formed integrally with the flange portion 23. The second lip seal member 21 is a single rubber-like elastic body, and the cylindrical fixing portion 22, the flange portion 23, and the second seal lip 24 are integrally formed by the rubber-like elastic body. Like the first seal lip 14, the second seal lip 24 is configured so that its pressure receiving surface 24a faces the machine inner side A and is pressed against the peripheral surface of the shaft 3 when receiving the sealing fluid pressure on the pressure receiving surface 24a. Has been. The second lip seal member 21 may be made of a sliding resin material such as PTFE.

  The backup ring 31 is fixed to the inner periphery of the cylindrical fixing portion 12 of the first lip seal member 11 on the machine outer side B of the second lip seal member 21, and suppresses excessive deformation of the second seal lip 24. . The backup ring 31 is made of a single metal plate (sheet metal press product), and a cylindrical fixing portion 32 fixed to the inner periphery of the cylindrical fixing portion 12 of the first lip seal member 11 by the metal plate; A flange portion 33 integrally formed radially inwardly at the outer end of the tubular fixing portion 32, and a taper portion 34 integrally formed obliquely inwardly at the inner peripheral end of the flange portion 33 Is integrally molded. The flange portion 33 and the taper portion 34 are disposed on the machine outside B of the second lip seal member 21 and form a back-up portion 35 for the second seal lip 24. Further, in order to insert the cylindrical fixing portion 32 of the backup ring 31, an annular step portion (insertion recess) 25 is provided on the outer peripheral portion of the second lip seal member 21 so as to open to the outer side B. .

  The first lip seal member 11, the second lip seal member 21 and the backup ring 31 fixed to the housing 2 side are each manufactured separately and assembled without using an adhesive, or an adhesive. Are integrated as appropriate.

  On the other hand, the rotating body 41 fixed to the shaft 3 side is formed into a ring shape (annular) as described above, is fixed to the outer periphery of the shaft 3 and rotates together with the shaft 3, and is pumped to the outer peripheral surface thereof. A mechanism 42 is provided over the entire circumference. Specifically, the pumping mechanism 42 is configured by a plurality of screw grooves 43 that are inclined with respect to the central axis 0. The screw groove 43 is formed so as to reach (penetrate) from the outer edge of the outer peripheral surface of the rotating body 41 to the inner edge of the machine, and the outer end and the inner end of the screw groove 43 are arranged in the circumferential direction. In other words, the inner end portion of the screw groove 43 is formed so as to be shifted to the rear side in the axial rotation direction rather than the outer end portion of the screw groove 43. Therefore, the rotating body 41 is sometimes referred to as a screw ring because a spiral screw is formed on the outer peripheral surface of the ring body. The material of the rotating body 41 is generally a metal (cast), but is not particularly limited, and may be resin, rubber, or the like.

  The rotating body 41 and the pumping mechanism 42 are disposed in the annular space 4 surrounded by the first and second lip seal members 11 and 21, but do not contact both the lip seal members 11 and 21. Non-contact. However, the screw groove 43 of the pumping mechanism 42 provided on the outer peripheral surface of the rotating body 41 is formed with a small radial gap C from the inner peripheral surface of the cylindrical fixing portion 22 of the second lip seal member 21 located on the outer peripheral side. Are facing each other.

  Further, a contact protrusion 17 is provided on the end surface of the flange portion 13 of the first lip seal member 11 so as to be in contact with and away from the end surface of the rotating body 41. The contact protrusion 17 is normally not in contact with the rotating body 41, but when the first seal lip 14 is pressed by the sealing fluid pressure and elastically deformed toward the outside B, the inside of the rotating body 41 is in contact. It abuts against the end face, and is thereby configured to suppress excessive deformation of the first seal lip 14. A plurality of protrusions 17 are provided in a uniform manner. The protrusion 17 is made of a rubber-like elastic body and is integrally formed on the end surface of the flange rubber portion 16c. Since the protrusion 17 is in sliding contact with the rotating body 41 at the time of contact, it is made of a resin having a low frictional resistance (for example, PTFE). It may be formed (separately formed) and adhered (retrofit) to the first lip seal member 11.

  When the sealing device 1 having the above-described configuration is attached to the shaft seal portion of the water pump, the first seal lip 14 on the machine inside A forms a primary seal and the second seal lip 24 on the machine outside B forms a secondary seal, Further, a third seal by the pumping mechanism 42 is arranged in the middle. Therefore, in the sealing device 1, the following effects are exhibited.

  That is, first, in the sealing device 1 having the above-described configuration, the first and second seal lips 14 and 24 are arranged side by side in the axial direction, thereby setting a multi-stage seal lip structure. Since the rotating body 41 is disposed in the space 4 between 24 and the pumping mechanism 42 is provided in the rotating body 41, the pumping mechanism 42 that rotates together with the rotation of the rotating body 41 by rotating the shaft 3. As a result, a return fluid pressure is generated, whereby a return pump action is exerted so as to return the fluid in the space 4 to the machine interior A. Since the pumping mechanism 42 is provided on the outer peripheral surface of the ring-shaped rotating body 41, the fluid further flows from the outer side B toward the inner side A on the outer peripheral side. Accordingly, even if there is a sealing fluid that passes through the first seal lip 14 on the machine inside A and enters the space 4, it can be returned to the machine inside A, and this sealing fluid can be returned to the second on the machine outside B. Since the arrival at the seal lip 24 can be delayed, leakage of a sealing fluid such as LLC from the inside A to the outside B can be effectively suppressed, and the sealing performance can be improved.

  Further, when the shaft 3 rotates and the rotating body 41 is driven to rotate, a return fluid pressure is generated in the space 4 by the pumping mechanism 42. Therefore, the first seal lip 14 on the machine inside A and the second seal on the machine outside B are used. With the lip 24, the acting load is reduced, and the contact surface pressure against the shaft 3 is reduced. A sealing fluid pressure acts on the pressure receiving surface 14a of the first seal lip 14 on the machine inner side A, but since a returning fluid pressure acts on the back side of the lip 14 against this, the subtraction causes the lip The load acting on 14 is reduced. If the two pressures antagonize, the lip 14 will be in a floating state, and if the latter return fluid pressure is greater, the lip 14 will also rise from the shaft 3. Further, the second seal lip 24 on the outer side B is depressurized in the space 4 due to the generation of the return fluid pressure, and accordingly, the load acting on the lip 24 is reduced. Therefore, since the load is alleviated and the contact surface pressure with respect to the shaft 3 is reduced, even if foreign matter such as casting sand is caught in the lip sliding portion, the damage received can be reduced. Therefore, early wear of the seal lips 14, 24 can be suppressed, and wear resistance can be improved.

  In addition, since the backup ring 31 is arranged further on the outer side B of the second seal lip 24 on the outer side B, it is possible to suppress excessive deformation of the second seal lip 24 and stabilize its posture. It is said that. Therefore, the sealing performance and wear resistance of the second seal lip 24 can be further improved.

  Further, since the second lip seal member 21 and the backup ring 31 are fixed together on the inner periphery of the cylindrical fixing portion 12 of the first lip seal member 11, the components are easily positioned and assembled easily. be able to.

  Further, a screw groove 43 of the pumping mechanism 42 is provided on the outer peripheral surface of the rotating body 41, and a small radial gap C between the inner peripheral surface of the cylindrical fixing portion 22 of the second lip seal member 21 located on the outer peripheral side thereof. Therefore, a kind of labyrinth portion is set in the radial gap C, so that a relatively large return fluid pressure can be generated in the radial gap C. Therefore, the return pump action by the pumping mechanism 42 can be made strong.

  Furthermore, an abutment protrusion 17 is provided on the outer end surface of the flange portion 13 of the first lip seal member 11, and the abutment protrusion 17 is configured to abut on and away from the inward end surface of the rotating body 41. Therefore, excessive deformation of the first seal lip 14 can be suppressed and the posture thereof can be stabilized. Therefore, the sealing performance and wear resistance of the first seal lip 14 can be further improved.

  In addition, about the said 1st Example, it is possible to add and change the structure as follows.

Second embodiment ...
In the first embodiment, the rotator 41 is made of a metal casting. Instead, as shown in FIG. 2, the rotator 41 is a pressed product of sheet metal. The sheet metal rotating body 41 shown in the figure is formed in a semi-cut section U shape or substantially U shape, and a screw groove (not shown) of the pumping mechanism 42 is provided on the outer peripheral surface thereof.

Third and fourth embodiments ...
In the first embodiment, the first seal lip 14 is slidably in close contact with the peripheral surface of the shaft 3, but instead, a sleeve in which the first seal lip 14 is fixed to the peripheral surface of the shaft 3 is used. 44 is configured to be slidably in close contact with the outer peripheral surface of 44.

  In the third embodiment of FIG. 3, a sleeve 44 is provided on the machine inner side A of the rotating body 41, the sleeve 44 is fixed to the peripheral surface of the shaft 3, and the first seal lip 14 slides on the outer peripheral surface of the sleeve 44. It is configured to move freely. The sleeve 44 is assembled integrally with the rotating body 41.

  In the fourth embodiment shown in FIG. 4, a sleeve 44 is integrally formed as a part of the sheet metal rotating body 41 toward the machine inner side A, and the sleeve 44 is fixed to the peripheral surface of the shaft 3. The first seal lip 14 is slidably in close contact with the outer peripheral surface. The sleeve 44 also serves as a cylindrical fixing portion of the rotating body 41 made of sheet metal.

  In any case, it is possible to prevent the seal lip 14 from being damaged by the shaft 3 by attaching the seal lip 14 and the sleeve 44 in advance to the outer periphery of the shaft 3. If the sleeve 44 is not provided, a mounting jig may be required to prevent the seal lip 14 from being damaged. However, according to this embodiment, the mounting jig is not necessary, and therefore the mounting workability can be improved. In the fourth embodiment shown in FIG. 4, the sleeve 44 also serves as the cylindrical fixing portion of the rotating body 41, so that diversification of component functions can be realized.

  Further, in the present invention, the pumping mechanism 42 only needs to generate a fluid flow toward the aircraft inner side A in the space 4 as described above, so the structure thereof is not particularly limited as long as it has this function. In the above embodiment, as a specific example of the pumping mechanism 42, the screw-like groove 43 is provided on the outer peripheral surface of the rotating body 41. However, for example, a blade-like one may be provided instead of the groove 43. good. Further, it may be provided not on the outer peripheral surface of the rotating body 41 but on the axial end surface thereof as a spiral shape, or may be provided inside the rotating body 41 as a through hole shape.

Sectional drawing of the principal part of the sealing device which concerns on 1st Example of this invention. Sectional drawing of the principal part of the sealing device which concerns on 2nd Example of this invention. Sectional drawing of the principal part of the sealing device which concerns on 3rd Example of this invention. Sectional drawing of the principal part of the sealing device which concerns on 4th Example of this invention. Sectional drawing of the sealing device which concerns on a prior art example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sealing device 2 Housing 3 Shaft 4 Space 11 First lip seal member 12, 22, 32 Cylindrical fixing part 13, 15b, 23, 33 Flange part 14 First seal lip 14a, 24a Pressure receiving surface 15 Metal ring 15a Cylindrical part DESCRIPTION OF SYMBOLS 16 Rubber-like elastic body 16a End surface rubber part 16b Outer peripheral rubber part 16c Flange rubber part 17 Contact protrusion 21 Second lip seal member 24 Second seal lip 25 Step part 31 Backup ring 34 Taper part 35 Backup part 41 Rotating body 42 Pumping mechanism 43 Thread groove 44 Sleeve 0 Center axis A Machine inside B Machine outside C Radial gap

Claims (4)

In the water pump sealing device (1) mounted between the housing (2) and the shaft (3) so that a sealing fluid such as LLC does not leak from the inside (A) to the outside (B),
A first seal lip (14) fixed to the housing (2) and slidably in close contact with the shaft (3) or a sleeve (44) fixed to the shaft (3);
A second seal lip (24) disposed on the outboard side (B) of the first seal lip (14);
A rotating body (41) disposed in a space (4) between the seal lips (14) and (24) and fixed to the shaft (3) and rotating together with the shaft (3);
A pumping mechanism (provided on the rotating body (41)) that exerts a return pumping action so as to return the sealed fluid that has passed through the first seal lip (14) and entered the space (4) to the inside (A). 42) and a sealing device for a water pump. In the water pump sealing device (1) mounted between the housing (2) and the shaft (3) so that a sealing fluid such as LLC does not leak from the inside (A) to the outside (B),
A flange portion (13) is integrally formed radially inwardly at the inner end of the tubular fixing portion (12) fixed to the inner periphery of the housing (2), and the flange portion (13) is A first lip seal member (11) integrally formed with a shaft (3) or a first seal lip (14) slidably in close contact with a sleeve (44) fixed to the shaft (3);
A flange portion (23) is directed radially inward at the outer end of the tubular fixing portion (22) fixed to the inner periphery of the cylindrical fixing portion (12) of the first lip seal member (11). A second lip seal member (21) integrally formed and a second seal lip (24) slidably in close contact with the shaft (3) on the flange portion (23);
The second lip seal member (21) is fixed to the inner periphery of the cylindrical fixing portion (12) of the first lip seal member (11) on the outer side (B) of the second lip seal member (21). A backup ring (31) for suppressing deformation of the
A rotating body (41) disposed in a space (4) between the seal lips (14) and (24) and fixed to the shaft (3) and rotating together with the shaft (3);
A pumping mechanism (provided on the rotating body (41)) that exerts a return pumping action so as to return the sealed fluid that has passed through the first seal lip (14) and entered the space (4) to the inside (A). 42) and a sealing device for a water pump. The water pump sealing device according to claim 2,
The pumping mechanism (42) is provided on the outer peripheral surface of the rotating body (41), and the inner peripheral surface of the cylindrical fixing portion (22) of the second lip seal member (21) located on the outer peripheral side is slightly radial. A sealing device for a water pump, characterized by facing each other with a gap (C). The water pump sealing device according to claim 2,
When the first seal lip (14) is pressed and deformed by the sealing fluid pressure, the first seal lip (14) comes into contact with the inner end surface of the rotating body (41) so as to be freely contacted and separated, thereby causing excessive deformation of the first seal lip (14). A sealing device for a water pump, wherein a contact protrusion (17) to be suppressed is provided on the first lip seal member (11).

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