JP2961687B2 - Lip type seal - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lip seal provided for sealing the periphery of a rotating shaft of a refrigerator compressor such as a cooling device.

[0002]

2. Description of the Related Art As a typical conventional example of this type of lip seal, as shown in FIG. 4, a main lip member 110 made of an elastomer, an inward flange 121 at a front end, and a caulking portion 122 at a rear end are respectively provided. A metal outer ring 120 formed by bending to the inner diameter side and excluding the caulking portion 122 is embedded in the mounting base 111 of the main lip member 110, and an outer diameter portion 131 is formed by mounting the base 111 of the main lip member 110. And a back lip member 130 made of a synthetic resin such as PTFE, which is in contact with the back surface of the lip member, and a metal inner ring 140 which is in contact with the caulking portion 122 and presses the back surface of the backup lip member 130. is there. In the description, “front” refers to a surface facing the inboard A side to be sealed, “back” refers to a surface facing the atmosphere B side, which is an anti-sealed space, and “tip” refers to the inboard A Side, and the “rear end” refers to the end on the atmosphere B side.

In this lip-type seal, a mounting base 111 of a main lip member 110 reinforced by an outer ring 120 is tightly fitted and fixed to an inner peripheral surface of a shaft sealing portion housing 1 of a refrigerator compressor. Main lip member 1 extending to A side
An inner diameter sliding portion 113a of a head 113 protruding toward the inner diameter side at the distal end of the ten cylindrical flexible portions 112 comes into sliding contact with the outer peripheral surface of the rotary shaft 2 inserted through the inner periphery of the housing 1. This prevents the refrigerant and refrigerating machine oil compressed in the machine A from leaking from the circumference of the shaft into the atmosphere B, which is an anti-sealing space.

As shown in FIG. 5, an inner diameter sliding portion 113 of the main lip member 110 has a substantially V-shaped cross section.
Assuming that α is the front side angle with respect to the outer peripheral surface of the rotating shaft 2 and β is the back side angle, the inner diameter sliding portion 11 of the head 113
To exhibit excellent sealing performance in 3a, α> β
It is known that it is necessary to. This is α> β
By doing so, the peak of the surface pressure of the inner diameter sliding portion 113a with respect to the outer peripheral surface of the rotating shaft 2 is distributed so as to be unevenly distributed on the sealed space side, and the fluid to be sealed composed of the refrigerant and the refrigerating machine oil intrudes into a wedge shape. This is because the effect of preventing the occurrence of blemishes increases.

[0005] The pressure of the refrigerant in the in-machine A of the refrigerator compressor is normally 1 to 7 kgf / cm ² G when pressurized, and the cylindrical flexible portion 112 of the main lip member 110 that is deformed toward the inner diameter side by this pressure is the same. The backup lip member 130 extending on the inner peripheral side is supported by the cylindrical support 132. That is, in a substantially no-load state when the in-machine A is at 1 kgf / cm ² G (1 atm), as shown in FIG. 5, the inner peripheral surface of the tubular flexible portion 112 of the main lip member 110 and the backup lip A gap δ is formed between the member 130 and the outer peripheral surface of the cylindrical support portion 32, and thereafter, the in-machine A
Is pressurized, as shown in FIG.
The deformation of the main lip member 110 toward the inner diameter side of the tubular flexible portion 112 due to the contact is restricted by the contact of the backup lip member 130 with the tubular support portion 132, whereby the head 113 with respect to the rotating shaft 2 at high pressure is The increase in the sliding load is alleviated. At this time, the outer peripheral edge 132a of the distal end of the cylindrical support 132 of the backup lip member 130
Is located rearward (on the side of the tubular flexible portion 112) from the boundary between the back surface of the head 113 of the main lip member 110 and the inner peripheral surface of the tubular flexible portion 112.

[0006]

The following problems are pointed out in the lip seal according to the prior art. In other words, the state shown in FIG. 6 is changed from the state shown in FIG. 5 to the state shown in FIG. 6 in which the cylindrical flexible portion 112 of the main lip member 110 is supported by the cylindrical support portion 132 of the backup lip member 130 when the inside A is pressurized. In the process of shifting, the main lip member 11
The head 113 of 0 is tilted so that the angle on the back side of the inner diameter sliding portion 113a decreases by β. Further, the tubular flexible portion 112 of the main lip member 110 is
30 after contact with the cylindrical support 132 of the
Is pressurized, the head 113 moves to the outer peripheral edge 132 of the distal end of the cylindrical support portion 132 of the backup lip member 130.
a and the inner diameter sliding portion 113a is curved and deformed toward the rotating shaft 2 by the pressure P, so that the contact width W with the outer peripheral surface of the rotating shaft 2 increases, and the amount of heat generated by sliding increases. It is feared that the elastomer of the inner diameter sliding portion 113a is deteriorated due to the occurrence of the leakage, and the leakage due to cracks or the like is caused by the deterioration.

Therefore, in order to make this type of lip seal sufficiently usable even under high pressure conditions, the above-described α
It is important to suppress an increase in the contact width W of the inner diameter sliding portion 113a of the head 113 due to the pressure P in the machine A while maintaining the relationship of> β. For this reason, in the prior art, the thickness of the cylindrical support portion 132 of the backup lip member 130 is reduced, and the inner peripheral sliding portion 113a of the head 113 and the outer peripheral edge 132a of the distal end of the cylindrical support portion 132 of the backup lip member 130 are formed. Is designed to be as small as possible. That is, as the distance L becomes smaller, the head 113 is less likely to be tilted or bent by the pressure P.

However, as the thickness of the cylindrical support portion 132 of the backup lip member 130 is reduced, the supporting force of the main lip member 110 on the cylindrical flexible portion 112 decreases accordingly. The cylindrical support portion 132 itself comes into contact with the rotating shaft 2 due to the deformation force from the cylindrical flexible portion 112 of the main lip member 110 and wears, and the backup lip member 130 is in a state where the inside A of the machine is in a vacuum state. When the main lip member 110
Has a function as a pressure reducing seal for reducing the pressure of the atmosphere B acting on the back surface of the cylindrical support 132.
If the wall thickness is reduced, the vacuum sealing function during such a vacuum operation is also reduced. Therefore, it is actually difficult to effectively suppress the increase in the contact width W by reducing the thickness L of the cylindrical support portion 132 to reduce the distance L.

The present invention has been made in view of the above circumstances, and a technical problem thereof is to increase a load due to a pressure acting on an inner diameter sliding portion of a main lip member made of an elastomer. An object of the present invention is to provide a lip-type seal that can be effectively suppressed and maintain excellent sealing performance even under high pressure conditions.

[0010]

Means for Solving the Problems The technical problems described above are:
This can be effectively solved by the present invention. That is, the lip-type seal according to the present invention has a rotating shaft attached to the distal end of a cylindrical flexible portion extending toward the sealed space from the inner peripheral side of the outer peripheral mounting base closely fitted to the inner peripheral surface of the housing. An elastomer main lip member having a head that is in sliding contact with the outer peripheral surface; and a cylindrical shape disposed on the back side of the main lip member and extending to the inner peripheral side of the cylindrical flexible portion of the main lip member. A backup lip member made of synthetic resin having a support portion, a gap between the tubular flexible portion of the main lip member and the tubular support portion of the backup lip member, and a cylindrical shape of the backup lip member. The outer peripheral edge of the tip end surface of the support portion is axially centered on the back side tapered surface of the head of the main lip member.
It is configured to reach the inner circumference between them.

The lip seal according to the present invention, like the conventional lip seal, prevents the fluid to be sealed in the sealed space from leaking to the atmosphere side when the inner diameter sliding portion of the main lip member comes into sliding contact with the outer peripheral surface of the rotating shaft. It is to prevent. When the sealed space is pressurized, the pressure causes the head of the main lip member to be displaced toward the inner diameter side. This displacement is caused by the tapered surface on the back side of the head being the tip of the cylindrical support portion of the backup lip member. It is regulated by contacting the outer edge.

Further, the head has an inner diameter sliding portion,
The pressure in the sealed space tends to bend and deform to the rotating shaft side between the contact portion of the distal end surface of the cylindrical support portion and the outer peripheral edge , but the pressure also causes the cylindrical flexible portion of the main lip member to have an inner diameter. As a result, a moment is generated with this displacement as a fulcrum about a contact portion with the outer peripheral edge of the distal end surface of the cylindrical support portion. Since this moment acts in the direction of preventing the bending deformation, an increase in the sliding load due to pressure is suppressed. Note that the outer peripheral edge of the distal end surface of the cylindrical support portion of the backup lip member is initially in the axial direction of the tapered surface of the head of the main lip member when the sealed space is not pressurized.
It may be configured to be in contact with the intermediate position .

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment considered to be the best of the present invention, and basically comprises a group of components similar to the conventional example of FIG. 4 described above. Reference numeral 1 denotes a shaft seal housing of a refrigerator compressor such as a cooling device.
Is a rotating shaft inserted through the inner periphery of the housing 1,
The lip-type seal according to this embodiment is mounted between the housing 1 and the rotating shaft 2 to prevent leakage of a fluid to be sealed such as a refrigerant and refrigerating machine oil in the machine A.

That is, in this lip-type seal, the main lip member 10 made of an elastomer, the inward flange 21 at the front end, and the caulked portion 22 at the rear end are formed by bending toward the inner diameter side, and the portion excluding the caulked portion 22 is the main lip member 10. A metal outer ring 20 embedded in the mounting base 11 of the lip member 10;
Reference numeral 1 denotes a backup lip member 30 made of a synthetic resin such as PTFE, which is in contact with the back surface of the mounting base 11 of the main lip member 10, and a backup lip member 30 fixed to the inner periphery of the outer ring 20 by a caulking portion 22. And a metal inner ring 40 for holding the back surface. The mounting base 11 of the main lip member 10 is tightly fitted and fixed to the inner peripheral surface of the shaft seal portion housing 1 of the refrigerator compressor, and the distal end of the tubular flexible portion 12 of the main lip member 10 extending to the inside A side is A head 13 projecting substantially in a tapered shape toward the inner diameter side as a whole is formed, and an inner diameter sliding portion 13 a having a substantially V-shaped cross section is slidably contacted with the outer peripheral surface of the rotating shaft 2.

As shown in FIG. 2, the front side tapered surface 1 of the inner diameter sliding portion 13a of the head 13 of the main lip member 10 is formed.
3b is larger than the angle β formed by the rear tapered surface 13c of the inner diameter sliding portion 13a with the outer peripheral surface of the rotary shaft 2 (α>
β). The backup lip member 30 has a cylindrical support portion 32 which is an inner peripheral portion thereof, and a cylindrical flexible portion 12 of the main lip member 10.
And the outer peripheral edge 32 a of the tip end surface of the cylindrical support portion 32 extends in the axial direction of the back side tapered surface 13 c of the head 13.
Has reached the contact position with the middle part . Thus, a gap S is formed between the inner peripheral surface of the cylindrical flexible portion 12 of the main lip member 10 and the cylindrical support portion 32 of the backup lip member 30.

In this embodiment, the pressure P in the inside A of the refrigerator compressor is normally 1 to 7 kgf / cm when pressurized.
2G, the head 13 of the main lip member 10 uses the pressure P acting on the outer peripheral side tapered surface 13d to cause the back side tapered surface 13c of the inner diameter sliding portion 13a and the distal end of the cylindrical support portion 32 of the backup lip member 30 to move. Outer peripheral edge 32a
Clockwise moment M in FIG.
Yields 1. On the other hand, the cylindrical flexible portion 12 of the main lip member 10
Is displaced toward the inner diameter side by the pressure P acting on the outer peripheral surface thereof so as to reduce the gap S between the backup lip member 30 and the cylindrical support portion 32. Accordingly,
A counterclockwise moment M2 is generated with the contact portion C as a fulcrum.

That is, since the moment M ₂ acts in a direction opposite to the moment M ₁ in the direction of increasing the sliding load of the inner diameter sliding portion 13 a of the head 13, the sliding load due to the increase of the internal pressure P is reduced. The increase is effectively mitigated. Therefore, if the deformation of the head 13 is neglected, the contact portion C is set such that the moment M ₁ and the moment M ₂ become substantially equal.
In theory, the increase in the sliding load due to the in-machine pressure P can be minimized.

Further, the moment M ₂ suppresses the displacement of the head 13 such that the angle α of the front tapered surface 13b of the head 13 of the main lip member 10 decreases and the angle β of the rear tapered surface 13c increases. Therefore, excellent sealing performance is maintained because the peak of the surface pressure of the inner diameter sliding portion 113a is unevenly distributed toward the sealed space due to the relationship α> β.

FIG. 3 is a diagram showing a head 1 according to a change in the internal pressure P.
3 shows the result of measuring the change in the contact width W of the inner diameter sliding portion 13a of the No. 3 with respect to the rotating shaft 2 in comparison with the above-described conventional example of FIG. From this measurement result, according to the lip-type seal of the embodiment of the present invention, it is recognized that the increase in the contact width due to the increase in the internal pressure P is significantly smaller than that of the conventional example. For example, the internal pressure P is 10 kgf / It can be seen that even under the condition of cm ² G, the contact width of the inner diameter sliding portion in the lip seal of the present embodiment is almost the same as the contact width of the conventional lip seal at about 1 kgf / cm ² G. Therefore, according to the lip-type seal of the present embodiment, the pressure inside the machine is 7 kgf / cm ² G
It can be used as a shaft seal device of a refrigerator compressor exceeding the above.

In the illustrated embodiment, the cylindrical support portion 32 of the backup lip member 30 is used even when the inside A of the machine is not pressurized.
The outer peripheral edge 32a of the tip surface of the head 1 of the main lip member 10
3 is in contact with the axially intermediate position of the back side tapered surface 13c , but when the inside of the machine A is in a non-pressurized state, the outer peripheral edge 32a of the front end surface of the backup lip member 30 is inside the back side tapered surface 13c. It is good also as composition which is in the peripheral side, and contacts when interior A is pressurized.

[0021]

According to the lip seal of the present invention, the head of the main lip member made of the elastomer is provided with the tip of the cylindrical support portion as the inner space is displaced by the pressure of the sealed space.
A moment is generated with the contact point of the end face with the outer peripheral edge as a fulcrum. This moment suppresses an increase in the sliding load on the outer peripheral surface of the rotating shaft due to the pressure, so that cracks and the like due to deterioration of the elastomer material of the head are reduced. Generation can be effectively prevented, and excellent sealing performance can be maintained even under high pressure conditions.

[Brief description of the drawings]

FIG. 1 is a half sectional view showing an embodiment of a lip seal according to the present invention by cutting along a plane passing through an axis together with a housing and a part of a rotating shaft.

FIG. 2 is an operation explanatory view in the embodiment.

FIG. 3 is an explanatory diagram showing the relationship between the internal pressure and the contact width of an inner diameter sliding portion of a main lip member in comparison with a conventional lip-type seal.

FIG. 4 is a cross-sectional view showing a lip-type seal according to the related art cut along a plane passing through an axis together with a housing and a part of a rotary shaft.

FIG. 5 is an explanatory diagram showing a situation at the time of no load in the conventional technique.

FIG. 6 is an explanatory diagram showing a situation at the time of high pressure in the above-described conventional technology.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Housing 2 Rotation shaft 10 Main lip member 11 Mounting base 12 Cylindrical flexible part 13 Head 13a Inner diameter sliding part 13c Back side tapered surface 30 Backup lip member 32 Cylindrical support part 32aOuter edge of tip surface  A Inside the machine (sealed space) S Clearance

Claims (2)

(57) [Claims] An outer peripheral surface of a rotary shaft is in sliding contact with a distal end of a cylindrical flexible portion extending from an inner peripheral side of an outer peripheral mounting base closely fitted to an inner peripheral surface of a housing toward a sealed space side. A main lip member made of an elastomer having a head to be formed, and a cylindrical support portion disposed on the back side of the main lip member and extending to the inner peripheral side of the cylindrical flexible portion of the main lip member. A backup lip member made of resin; and a gap between the tubular flexible portion of the main lip member and the tubular support portion of the backup lip member, and a tip of the tubular support portion of the backup lip member. The outer peripheral edge of the surface is the axial direction of the back side tapered surface of the head of the main lip member
A lip-type seal that reaches the middle inner circumference . 2. The method according to claim 1, wherein the cylindrical support portion of the backup lip member has
The outer peripheral edge of the front end surface is at the axially intermediate position of the tapered surface on the back side of the head of the main lip member in the unpressurized state of the sealed space.
Lip type seal according to claim 1, characterized in that are in contact.