JPH07139634A - Rotary shaft seal - Google Patents

Abstract

PURPOSE:To effectively prevent the leakage of a fluid when a rotary shaft is stopped, and prevent the bending and sticking-out phenomenon of the seal element to the lower pressure side. CONSTITUTION:In a seal of a rotary shaft provided with a seal element 9 having a seal lip part 16 with a spiral groove H in plane contact with an outer circumferential surface 4 of the rotary shaft 3, the spiral groove H and a flat surface part to shut off the spiral groove H are formed on the contact surface 17 of the rotary shaft of the seal lip part 16.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to rotary shaft seals.

[0002]

2. Description of the Related Art Generally, in a compressor for a car air conditioner, a refrigerant (gaseous and liquid in which oil is dissolved) and refrigerating machine oil are used as a sealed fluid and kept at a predetermined pressure. Therefore, it is necessary to prevent fluid leakage when the rotating shaft is stationary and rotating.

Therefore, a rotary shaft seal as shown in FIG. 8 has been developed. This rotary shaft seal includes a first holding metal fitting a,
A first seal element b, a second holding metal fitting c, and a second sealing element e sandwiched between the second holding metal fitting c and the first sealing element b are provided and assembled as shown in the example. Attached.

Then, the seal lip portion d of the first seal element b is brought into close contact with the outer peripheral surface of the rotating shaft g so that the rotating shaft g
Fluid h from the fluid storage chamber k to the low pressure side m
Leakage is prevented, and further, the seal lip portion i with the spiral groove j of the second seal element e is brought into contact with the outer peripheral surface of the rotating shaft g to generate a pumping action accompanying the rotation of the rotating shaft g, thereby lowering the pressure of the fluid h. The side m is circulated to the fluid storage chamber k to prevent leakage when the rotating shaft g is rotated.

The spiral groove j of the second seal element e
Was formed so that the tip end side (the fluid storage chamber k side) of the seal lip portion i and the low-pressure side m communicate with each other in a spiral communication minute path.

[0006]

However, in the car air-conditioning compressor, when the rotating shaft g is left stationary for a long period of time, the self-sealing effect of the seal lip portion d of the first seal element b is particularly high. In a room temperature / low pressure state in which the temperature decreases, the mixed fluid h of pressured refrigerant and refrigerating machine oil is Although it is a small amount from the storage chamber k side, it passes through the seal lip portion d, so there is a problem that it leaks to the low pressure side m through the spiral groove j.

Moreover, since the spiral groove j reaches the curved portion n of the second seal element e, the strength and rigidity of that portion are insufficient, and when a high pressure is applied from the fluid storage chamber k side, the curved portion j is curved. There is a problem that bending of the portion n and protrusion to the low pressure side m are likely to occur.

Therefore, an object of the present invention is to provide a rotary shaft seal capable of effectively preventing fluid leakage when the rotary shaft is stationary and preventing bending of the seal element and protrusion of the seal element to the low pressure side.

[0009]

In order to achieve the above object, a rotary shaft seal according to the present invention includes a rotary element having a sealing element having a spiral grooved seal lip portion which makes surface contact with an outer peripheral surface of the rotary shaft. A shaft seal, in which the spiral groove and a flat surface portion that blocks the spiral groove are formed on the rotary shaft contact surface of the seal lip portion.

[0010]

The flat surface portion of the seal lip portion of the seal element blocks the spiral groove in the middle of the contact surface of the rotating shaft and makes a surface contact with the outer peripheral surface of the rotating shaft to make close contact therewith. Even if it penetrates into the spiral groove, the fluid is surely sealed at the flat surface portion and no leakage occurs to the low pressure side.

Since the spiral groove is not formed in the curved root portion of the seal lip portion of the seal element, bending or protrusion to the low pressure side when a high pressure acts on the seal lip portion from the fluid storage chamber side. The resistance to is great.

[0012]

The present invention will be described in detail below with reference to the drawings illustrating the embodiments.

FIG. 1 shows a rotary shaft seal according to the present invention.
This rotary shaft seal is, for example, fitted between a hole 2 of a housing 1 such as a case of a compressor and a rotary shaft 3, and slidably contacts an outer peripheral surface 4 of the rotating rotary shaft 3 to form a fluid storage chamber. The fluid M having a predetermined pressure in R is sealed.

In the illustrated example, the retaining ring 5 fixed to the inner peripheral surface 2a of the hole 2 of the housing 1 prevents the rotary shaft seal from coming off.

Therefore, the rotary shaft seal has an annular first holding metal fitting 6 having an inner collar portion 10 at one end edge (on the side of the fluid storage chamber R) and a first holding metal fitting fixed to the first holding metal fitting 6. The seal element 7, the annular second holding metal fitting 8 having an inverted L-shaped cross section that is fitted into the first holding metal fitting 6, and the caulking T on the other end edge (on the low pressure side L) of the first holding metal fitting 6 A second sealing element 9 made of a synthetic resin (such as a fluorine-based resin (PTFE) such as ethylene tetrafluoride resin) sandwiched between the second holding metal fitting 8 and the first sealing element 7; There is.

The annular first seal element 7 made of a rubber elastic body is in contact with the seal lip portion 11 contacting the outer peripheral surface 4 of the rotary shaft 3 and the inner peripheral surface 2a of the hole portion 2 and is also the first holding metal fitting. 6, an outer peripheral contact piece portion 12 that covers the outer peripheral surface 14 of the reference numeral 6, a connecting piece portion 13 that connects the outer peripheral contact piece portion 12 and the seal lip portion 11 and covers the inner collar portion 10, and has a U-shaped cross section. Consists of.

The seal lip portion 11 has a substantially V-shaped cross section, and its tip portion is inclined at a predetermined angle in the inner diameter direction and the fluid storage chamber R direction. At the tip of the seal lip portion 11,
When the rotary shaft 3 is stationary, the inner peripheral projection 11a is formed so as to project in the inner diameter direction and contact (sliding contact) the outer peripheral surface 4 of the rotary shaft 3 in a substantially line contact manner. The ridges 11a are elastically pressed into close contact with each other to seal the fluid M.

A plurality of outer peripheral ridges 15 ... Are formed on the outer peripheral surface of the outer peripheral abutting piece 12, and the outer peripheral ridges 15 ... The leakage of the fluid M from the fluid storage chamber R on the surface 2a side to the low pressure side L is prevented.

The second sealing element 9 is formed in the shape of an annular flat plate as shown in FIG. 2, and then the inner peripheral edge is bent toward the fluid storage chamber R side as shown in FIG. ,
The seal lip portion 16 comes into surface contact with the outer peripheral surface 4 of the rotating shaft 3.

On the rotary shaft contact surface 17 of the seal lip portion 16,
Tip portion 19 of seal lip portion 16 and first seal element 7
The spiral groove H, one end of which communicates with the gap 20 between the seal lip portion 11 and the spiral groove H, is interrupted on the way to the low pressure side L and the other end of the spiral groove H is not communicated with the low pressure side L. And a flat surface portion 18 having a shape.

As shown in FIG. 2, the spiral groove H is formed around the axis of the second seal element 9 in the form of an annular flat plate. It should be noted that the pitch P of the spiral groove H can be freely changed and may be equal pitch or unequal pitch.

As shown in FIG. 3, the spiral groove H has a contact surface 17
Is formed obliquely from the low pressure side L to the low pressure side L. The spiral groove H is in a closed state when the contact surface 17 of the seal lip portion 16 is not in surface contact with the outer peripheral surface 4 of the rotating shaft 3, but when the surface is in contact as shown in the figure, the low pressure is applied from the fluid storage chamber R side. Sequentially opening toward the side L, and sufficient contact to seal the leakage of the fluid M from the fluid storage chamber R to the low pressure side L in the region between the grooves defined by the open spiral groove H. The surface pressure can be increased.

Further, the spiral groove H is formed in a rotational direction that causes a pumping action such that the fluid M that has entered the spiral groove H is returned to the fluid storage chamber R. Therefore, when the rotating shaft 3 rotates, the accompanying rotating flow due to the viscosity of the fluid M is generated from the low pressure side L in the direction of the fluid storage chamber R, and the spiral groove H is generated.
The fluid M that has entered the inside is pushed back, and the fluid M to the low pressure side L
Can prevent leakage.

Since the spiral groove H is not formed in the curved portion 21 of the second seal element 9, the strength and strength of that portion are
Even if a high pressure acts on the second seal element 9 from the fluid storage chamber R side without bending the rigidity, it is possible to prevent the bending portion 21 from bending or the protrusion to the low pressure side L.

Next, the flat surface portion 18 prevents the fluid M from leaking from the fluid storage chamber R side to the low pressure side L when the rotary shaft 3 is stationary for a long period of time. That is, even if the fluid M leaks from the fluid storage chamber R into the void portion 20 and enters the spiral groove H, the flat surface portion
Since 18 blocks the spiral groove H in the middle of the contact surface 17 and is in close contact with the outer peripheral surface 4 of the rotating shaft 3 in a surface contact manner, the fluid M is reliably sealed and no leakage occurs to the low pressure side L. .

The position of the flat surface portion 18 on the contact surface 17 can be freely changed. For example, the flat surface portion 18 may be disposed on the connecting surface 17 on the tip end 19 side as shown in FIG. 4, or the flat surface portion 18 may be flat as shown in FIG. Even if the surface portion 18 is disposed in the middle portion of the contact surface 17, the above-mentioned sealing effect is effectively achieved. However, if the flat surface portion 18 is disposed on the contact surface 17 on the curved portion 21 side as shown in FIG. Since the pressing force of the flat surface portion 18 against the outer peripheral surface 4 of 3 becomes the highest, the sealing action is further increased and stabilized.

However, the present invention can be applied to the embodiments shown in FIGS. 6 and 7 in addition to the embodiments shown in FIGS.

In the embodiment of FIG. 6, the first holding metal fitting 6 is O
The first seal element 7 having an outer concave circumferential groove 23 into which the ring 22 is fitted and which is a rubber elastic body has a seal lip portion 11 having a substantially V-shaped cross section, and the seal lip portion 11 is continuously provided to the seal lip portion 11. The one holding metal fitting 6 includes a holding portion 24 that is held in a fitting manner, and a reinforcing metal fitting 25 is embedded in the holding portion 24.

The other structure is the same as that of the embodiment shown in FIG. Therefore, the embodiment shown in FIG. 6 has the same operation and effect as the embodiment shown in FIG.

In the embodiment shown in FIG. 7, the first seal element 7 and the second seal element 9 have the same construction as the second seal element 9 shown in FIG. 1, respectively, and are the same as the embodiment shown in FIG. In the first holding metal fitting 6 in order from the fluid storage chamber R side to the low pressure side L, the supporting metal fitting 26, the first seal element 7, the intermediate metal fitting 27, the second seal element 9, the gasket 28, and the second holding metal fitting. 8 is attached.

In the embodiment of FIG. 7, the same action and effect as the second seal element 9 of FIG. 1 are exhibited, and due to the synergistic effect of both seal elements 7 and 9 when the rotary shaft 3 is rotating and stationary. Therefore, the leakage of the fluid M from the fluid storage chamber R side to the low pressure side L can be reliably prevented. In the illustrated example, the flat surface portion 18 is provided on both the first seal element 7 and the second seal element 9, but it may be provided on only one of them.

Next, regarding the seal of the present invention shown in FIG. 1 and the conventional seal shown in FIG. 8, under the conditions shown in Table 1, the rotating shaft 3
Table 2 shows the results of the sealing performance test when the sample was stationary.

[0033]

[Table 1]

[0034]

[Table 2]

As described above, in the seal of the present invention, not only when it is left in a relatively high temperature and high pressure state, but also at a normal temperature and low pressure state where the self-sealing effect of the seal lip portion 11 of the first seal element 7 is reduced. Even if left unattended, no fluid leakage occurred in Samples A and B, and conventional seals (Samples A and B)
It can be seen that, as compared with the above, extremely excellent sealing performance is exhibited when the rotating shaft 3 is stationary.

[0036]

Since the present invention is configured as described above, it has the following effects.

The present invention is particularly suitable as a rotary shaft seal for a compressor for a car air conditioner, and when the rotary shaft 3 is stationary, a fluid M that tends to leak from the spiral groove H to the low pressure side L.
Can be reliably sealed by the flat surface portion 18 of the seal element 9, so that the sealing performance is stable.

Further, since the spiral groove H is formed only in the rotary shaft contact surface 17, even if a high pressure is applied to the seal lip portion 16 of the seal element 9 from the fluid storage chamber R side, the seal lip portion 16 is formed. It is possible to prevent the bending and the protrusion to the low pressure side L.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a plan view showing a state before bending the inner peripheral edge portion of the sealing element.

FIG. 3 is an enlarged sectional view of a main part.

FIG. 4 is an enlarged sectional view of an essential part showing a modified example of the seal element.

FIG. 5 is an enlarged sectional view of an essential part showing another modification of the seal element.

FIG. 6 is a cross-sectional view showing another embodiment.

FIG. 7 is a sectional view showing another embodiment.

FIG. 8 is a cross-sectional view showing a conventional example.

[Explanation of symbols]

 3 rotary shaft 4 outer peripheral surface 9 seal element 16 seal lip 17 rotary shaft contact surface 18 flat surface H spiral groove

Claims (1)

[Claims] 1. A rotary shaft seal comprising a seal element having a seal lip portion with a spiral groove that makes surface contact with the outer peripheral surface of the rotary shaft, wherein the spiral groove is provided on the rotary shaft contact surface of the seal lip portion. A rotary shaft seal, wherein a flat surface portion that blocks the spiral groove is formed.