JPH06300141A - Lip type seal - Google Patents

Abstract

PURPOSE:To maintain sealing ability for a long period through suppression of the occurrence of the crack and abnormal wear of a slide part even when a pressure in a seal space is increased during rotation of a shaft by a method wherein the seal space is communicated with a pressure introduction chamber between the base part of a seal body and an annular protrusion part through a pressure introduction passage. CONSTITUTION:A seal body 20 comprises a base part 21; and an inside diameter lip part 23 extended to the atmosphere B side and brought into contact with the outer peripheral surface of a shaft 6. An annular protrusion part 24 is formed on the outer peripheral surface of a pressure receiving part 22 between the base part 21 and the inside diameter lip 23. In which case, the inner peripheral surfaces of the base part 21 and the pressure receiving part 22 are brought into non-contact with the shaft 6. The end part on the seal space A side of the slide surface 23a of the inside diameter lip part 23 is positioned closer to the seal space A side than the close contact part of the annular protrusion part 24. A pressure introduction chamber 12S is communicated with the seal space A through a pressure introduction hole 15 between the base part 21 and the annular space part 24. This constitution brings the inside diameter lip part 23 into slide over the shaft 6 at a proper bearing.

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 which is used as a shaft sealing device for a refrigerator compressor such as a cooling device.

[0002]

2. Description of the Related Art Conventionally, there has been a lip type seal as shown in FIG. 5 as a shaft sealing device used for a compressor of an air conditioner for an automobile. The lip-type seal is attached to the mounting portion 1 formed in the shaft hole of the compressor housing 106.
An elastomeric lip member 102 having an outer diameter base reinforced by a metal ring 103 on the inner space of a metal case 101 that is tightly fitted and fixed to the 06a through an O-ring 107, and is on the sealed space (inside the machine) A side; The PTFE lip member 104, which is attached to the atmosphere (anti-sealing space) B side and prevents the elastomer lip member 102 from being deformed to some extent in the inner diameter direction by the pressure of the sealed space A, and the PTFE lip member 104. The metal backup rings 105 supported from the atmosphere B side are held in a state where their outer diameter portions are in close contact with each other, and the inner diameter portion 102a of the elastomer lip member 102 is in airtight sliding contact with the outer peripheral surface of the shaft 108 to form a sealed space. The refrigerant (CFC) and refrigerating machine oil in A are prevented from leaking into the atmosphere B.

[0003]

By the way, there are piston type, rotary type, scroll type, etc. as compressors for automobile air conditioners, and the pressure inside the machine (sealed space A) that acts on the shaft sealing device when the shaft is rotated is There are various types, but since it is generally 4 kg / cm ² G or less, sufficient sealing performance and pressure resistance can be expected even with the lip-type seal of the above conventional structure. However, in the case of a compressor that generates a high pressure such that the internal pressure acting on the shaft sealing device becomes 4 kg / cm ² G or more when the shaft rotates, using the above lip-type seal as the shaft sealing device causes a sealed space. The high pressure of A overcomes the supporting force of the PTFE lip member 104 to largely bend the elastomer lip member 102 toward the inner diameter side and presses the inner diameter portion 102a against the shaft 108, so that the sliding width of the inner diameter portion 102a increases. However, the amount of heat generated by sliding also increases accordingly, and there is a problem that cracks and abnormal wear occur due to deterioration of the elastomer material and the sealing performance and durability are impaired.

The present invention has been made in view of the above circumstances, and its technical problem is to prevent cracks and abnormal wear of sliding parts even when the sealed space has a high pressure when the shaft rotates. It is to suppress and maintain the sealing property for a long time.

[0005]

The above-mentioned technical problems are as follows.
The present invention can effectively solve the problem. That is, in the lip-type seal according to the present invention, the elastomer seal body held on the inner circumference of the metal case extends to the atmosphere side with the base portion fixedly adhered to the end of the case on the sealed space side. And an inner diameter lip portion that is in sliding contact with the outer peripheral surface of the shaft and an outer peripheral surface of the pressure receiving portion between the base portion and the inner diameter lip portion, and is in close contact with a radial surface of the case facing the sealed space side. An annular protrusion, the inner peripheral surfaces of the base and the pressure receiving portion are not in contact with the shaft, and the end of the sliding surface of the inner diameter lip portion on the sealed space side is axially opposed to the radial surface and the annular protrusion. Is located closer to the sealed space than the close contact portion with the portion, and a pressure guiding chamber is formed on at least one of the case and the seal body, the pressure guiding chamber being on the outer periphery of the pressure receiving portion and between the base portion and the annular protrusion. Communicates with the sealed space via the pressure introduction path There. Further, in the present invention, more preferably, in the case, the axial displacement and the radial displacement of the inner diameter lip portion toward the atmosphere side are restricted so that the sliding surface is located closer to the sealed space than the close contact portion of the annular protrusion. A stopper surface is formed to be held on.

[0006]

[Operation] The pressure of the sealed space introduced through the pressure introducing passage into the pressure guiding chamber between the base of the seal body and the annular projection acts so as to press the pressure receiving portion of the seal body from the outer peripheral side to the shaft side. To do. On the other hand, the pressure of the sealing space which is the sealing space side of the inner diameter lip portion and extends to the inner peripheral surface of the pressure receiving portion which is not in contact with the shaft acts so as to float the pressure receiving portion to the outer diameter side, and the force in the pressing direction is applied. Although offsetting each other, the radial surface facing the sealed space side of the case and the annular protrusion are in close contact with each other at a position closer to the atmosphere than the end of the sliding surface of the inner diameter lip portion on the sealed space side, The force received by the pressure receiving portion from the outer peripheral side by the pressure of the sealed space introduced into the pressure guiding chamber is slightly larger than the force received from the inner peripheral side, and due to the radial unbalance component of the pressure on the pressure receiving portion, the inner diameter is The lip contacts the shaft with appropriate surface pressure.

Since the seal body is made of elastomer,
By the pressure of the sealed space acting on the inner peripheral surface of the pressure receiving portion,
The inner diameter lip portion is axially deformed and moved toward the atmosphere side.
When the amount of movement increases and the sliding surface of the inner diameter lip moves to the atmosphere side rather than the close contact between the annular protrusion of the seal body and the radial surface of the case, the pressure in the sealed space causes the seal body to move to the outer periphery. The force received from the inner peripheral side is larger than the force received from the side, and a gap is created between the shaft and the shaft, leading to leakage.However, such deformation movement of the inner diameter lip part It is regulated by a stopper surface formed at the end on the atmosphere side of.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, one embodiment of the lip type seal 1 according to the present invention will be described with reference to FIGS. That is, as shown in FIG. 1, the lip-type seal 1 includes an annular metal case 10 and an elastomer seal body 20 held on the inner circumference of the case 10.

As shown in FIG. 3, the case 10 has an annular first accommodating portion 1 formed on the inner peripheral surface of the end portion on the sealed space A side.
1 and the first accommodating portion 11 extending from there to the atmosphere B side
Second accommodating portion 12 formed to have a smaller diameter, a third accommodating portion 13 further extending from the second accommodating portion 12 toward the atmosphere B side and having a smaller diameter than the second accommodating portion 12, and having an outer peripheral surface on the atmosphere B side. It has an annular groove 14 formed so as to be unevenly distributed, and a pressure introducing hole 15 that is formed to penetrate the second accommodation portion 12 in the radial direction. Further, as shown in FIG. 4, the seal body 20 has a base portion 21 reinforced by a metal reinforcing ring 21a embedded therein and extending in a flange shape to the outer diameter side, and an inner diameter portion of the base portion 21 to the atmosphere B side. Pressure receiving portion 22 extending toward the atmosphere B and an inner diameter lip portion 2 extending further from the inner diameter portion of the pressure receiving portion 22 toward the atmosphere B side.
3 and an annular protrusion 24 that is formed to project on the outer peripheral surface of the pressure receiving portion 22.

The case 10 is hermetically press-fitted into an expansion chamber 3a formed in a shaft hole of a housing 3 of a cooling machine compressor, for example, through a packing (O ring) 2 housed in an annular groove 14. The axial movement is restricted by the snap ring 4 fitted in the groove on the peripheral wall surface of the expansion chamber 3a. The seal body 20 has the outer diameter portion of the base portion 21 tightly accommodated in the first accommodation portion 11 of the case 10, and the end portion 16 of the case 10 on the sealed space A side is caulked to make the metal washer. It is fixed through 4.

The annular protrusion 24 of the seal body 20 is in close contact with the radial surface 12a of the second accommodating portion 12 facing the sealed space A side of the case 10 at an appropriate compression margin, whereby the second accommodating portion is accommodated. The portion 12 includes a pressure receiving portion 22 of the seal body 20.
A pressure guiding chamber 12S, which is sealed by the close contact surface of the annular protrusion 24 and the close contact surface of the base portion 21 and communicates with the sealed space A through the pressure introduction hole 15 of the case 10, is formed on the outer peripheral side of the. The inner diameter lip portion 23 of the seal body 20 is inside the third housing portion 13 of the case 10, and the annular sliding surface 23 a formed on the inner peripheral surface of the inner diameter lip portion 23 so as to project into the shaft hole of the housing 3. The outer peripheral surface of the shaft 6 rotatably inserted is in contact with the outer peripheral surface of the shaft 6 in a state in which the diameter is slightly larger than the original shape shown in FIG. Base portion 21 and pressure receiving portion 2 of the seal body 20
The inner peripheral surface of 2 has a larger diameter than the sliding surface 23a of the inner diameter lip portion 23 and is not in contact with the outer peripheral surface of the shaft 6.

The annular projection 24 of the seal body 20 and the radial surface 12a of the second accommodating portion 12 are more axial than the end of the sliding surface 23a of the inner diameter lip 23 with respect to the outer peripheral surface of the shaft 6 on the sealed space A side. The position is slightly closer to the atmosphere B by the direction distance δ. The wall surface of the third accommodating portion 13 formed in the case 10 serves as an axial stopper surface 13a that closely opposes the tip end portion of the inner diameter lip portion 23 accommodated in the case 10 and restricts axial displacement thereof toward the atmosphere B side. , A radial stopper surface 13b that closely faces the outer peripheral surface of the inner diameter lip portion 23 and restricts the displacement in the outer radial direction. The recesses 21b and 21c formed in the base portion 21 are traces of protrusions for supporting the reinforcing ring 21a in the mold when the seal body 20 is molded.

In the mounted state shown in FIG. 1, the packing 2
The pressure in the sealed space A introduced into the pressure guiding chamber 12S through the gap G1 between the housing 3 and the case 10 on the side of the sealed space A and the pressure introduction hole 15 causes the inner diameter of the outer circumference of the pressure receiving portion 22 of the seal body 20 to increase. It acts to push it to the side. On the other hand, the pressure of the sealed space A introduced into the gap G2 between the inner peripheral surface of the pressure receiving portion 22 and the outer peripheral surface of the shaft 6 is the pressure receiving portion 22.
Acts to lift up to the outer diameter side. Here, the end portion of the pressure guiding chamber 12S due to the close contact between the annular protrusion 24 and the radial surface 12a of the case 10 is the end portion of the gap G2 on the inner circumference of the pressure receiving portion 22 due to the sliding surface 23a of the inner diameter lip portion 23. Since it is located on the atmosphere b side by a distance δ in the axial direction, the force F1 that the pressure receiving portion 22 receives from the outer peripheral side by the pressure of the sealed space A introduced into the pressure guiding chamber 12S is as shown in FIG. Due to the pressure of the sealed space A introduced into the gap G2, the pressure receiving portion 2
2 is slightly larger than the force F2 received from the inner peripheral side by ΔF. Therefore, the inner diameter lip portion 23 is elastically restored by being mounted in a slightly expanded state and the difference ΔF between the radial forces F1 and F2 received by the pressure receiving portion 22 due to the pressure in the sealed space A. The outer peripheral surface of the shaft 6 is slidably contacted with an appropriate surface pressure.

Further, due to the pressure of the sealed space A introduced into the gap G2 on the inner circumference of the pressure receiving portion 22, the inner diameter lip portion 2
Since the sliding surface 23a of the inner circumference is deformed and moved in the axial direction toward the atmosphere B side as indicated by the arrow X1, the stationary seal portion by the annular protrusion 24 and the sliding surface The axial distance δ from the end of the sliding seal portion on the sealed space A side by the moving surface 23a decreases. Therefore, even if the sealed space A has a high pressure, the pressing force ΔF against the sliding surface 23a hardly increases.

However, due to the high pressure in the sealed space A, the inner diameter lip portion 23 is deformed in the direction of the arrow X1 and the tip of the inner diameter lip portion 23 is lifted in the outer diameter direction as indicated by the arrow X2. Deformation becomes noticeable, which causes the sliding surface 23a to move toward the annular projection 24 and the case 10.
When it comes to be located on the atmosphere B side of the stationary seal portion formed by the radial surface 12a of the above, the force F2 acting on the inner circumference is larger than the force F1 acting on the outer circumference of the pressure receiving portion 22 by the pressure of the sealed space A. Therefore, the sliding surface 23a may be separated from the outer peripheral surface of the shaft 6 to cause leakage.
The axial stopper surface 13a and the radial stopper surface 13b in the third accommodating portion 13 of the case 10 regulate such deformation of the inner diameter lip portion 23, that is, the axial stopper surface 13a moves in the direction of the arrow X1. By restricting the deformation movement and the radial stopper surface 13b restricting the deformation movement in the arrow X2 direction, the sliding surface 23a is more sealed than the stationary sealing surface between the annular projection 24 and the radial surface 12a of the case 10. It is held at the position on the side of the space A.

In the above embodiment, the pressure guiding chamber 1
The pressure introducing hole 15 is provided as a case 1 as a pressure introducing path to the 2S.
However, the pressure introducing passage may be a hole or groove formed so as to penetrate the base portion 21 of the seal body 20 in the axial direction or the pressure receiving portion 22 in the radial direction,
In addition, the shapes of the details are not limited to those shown in the drawings.

[0017]

According to the lip-type seal of the present invention, the force F applied to the seal body from the outer peripheral side by the pressure in the sealed space.
1 and the force F2 received from the inner circumference side are partially balanced in the radial direction, and the pressure of the sealing space acting on the inner circumference of the seal body is equal to the pressure receiving area of the force ΔF for pressing the inner diameter lip portion against the shaft. Since it acts so as to decrease, even if the sealed space has a high pressure, the surface pressure of the sliding surface of the inner diameter lip portion and the sliding width hardly increase. Further, the deformation of the inner diameter lip portion such that the force F2 from the inner peripheral side of the pressure receiving portion due to the pressure of the sealed space becomes larger than the force F1 from the outer peripheral side is prevented by the stopper surface of the case. Always contacts the shaft with appropriate surface pressure. Therefore, abnormal wear due to an increase in the surface pressure of the sliding surface and the occurrence of cracks due to an increase in the amount of heat generated by sliding are prevented, and stable sealing performance can be maintained.

[Brief description of drawings]

FIG. 1 is a half sectional view of a preferred embodiment of a lip-type seal according to the present invention, taken along a plane passing through its axis.

FIG. 2 is a diagram for explaining the operation of the lip-type seal.

FIG. 3 is a half cross-sectional view of the case of the lip-type seal taken along a plane passing through the axis thereof.

FIG. 4 is a half cross-sectional view of the seal body of the lip type seal taken along a plane passing through the axis thereof.

FIG. 5 is a half cross-sectional view of a typical conventional lip type seal taken along a plane passing through its axis.

[Explanation of symbols]

 1 lip type seal 2 packing 3 housing 6 shaft 10 case 12a radial surface 12S pressure guiding chamber 13a axial stopper surface 13b radial stopper surface 15 pressure introducing hole 20 seal body 21 base 22 pressure receiving portion 23 inner diameter lip portion 23a sliding surface 24 Annular protrusion

Claims (2)

[Claims] 1. An annular metal case having a packing attached to an outer peripheral surface thereof, and an elastomer seal body held on an inner periphery of the case, the seal body being provided on a side of a sealed space of the case. It is formed on the outer peripheral surface of the pressure receiving portion between the base portion and the inner diameter lip portion, the base portion fixedly adhered to the end portion, the inner diameter lip portion extending to the atmosphere side and sealingly slidingly contacting the outer peripheral surface of the shaft. And a ring-shaped protrusion that is in close contact with the radial surface of the case facing the sealed space, the inner peripheral surfaces of the base portion and the pressure receiving portion are not in contact with the shaft, and the sliding surface of the inner diameter lip portion is sealed. The end portion on the space side is located closer to the sealed space in the axial direction than the close contact portion between the radial surface and the annular projection portion, and is the outer circumference of the pressure receiving portion, and the pressure guiding between the base portion and the annular projection portion. The chamber has less of the case and seal body Lip type seal, characterized in that also in communication with the sealed space through the pressure introduction passage formed in the one. 2. The case according to claim 1, wherein the sliding surface is closer to the sealed space than the close contact portion of the annular protrusion, by restricting axial displacement and outward displacement of the inner diameter lip portion toward the atmosphere. Lip type seal characterized in that a stopper surface for holding at the position of is formed.