JP2002005305A - Rotating shaft seal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent abrasion in an early stage of a sealing surface of a lip tip part at a pressure side, reduce abrasion resistance (torque), and secure sealing property during stopping of a rotating shaft when a high pressure is exerted as well as during rotating of the rotating shaft. SOLUTION: This rotating shaft seal is equipped with a front seal member 5 provided on a fluid accommodation chamber 33 side and having a lip tip part 13b made of rubber slidably brought into contact with the rotating shaft 32. The rotating shaft seal is further equipped with a rear seal member 25 provided on a low pressure side 42 and having a lip tip part 27b made of rubber brought into contact with the rotating shaft 32 in a state of stopping to carry out sealing operation is coated on the sealing surfaces S and S' of the lip tip parts 13b and 27b are coated with diamond-like carbon.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary shaft seal according to the present invention, and more particularly, to CO _{2 in a} compressor for a car air conditioner.
The present invention relates to a rotary shaft seal used for sealing a high-pressure fluid such as a gas.

[0002]

2. Description of the Related Art Conventionally, as this kind of rotary shaft seal,
The one shown in FIG. 8 is known. That is, the rotating shaft seal is provided in a housing 31 such as a compressor case.
, And is interposed between the rotation shafts 32 to seal the liquid or gas in the fluid storage chamber 33.

The structure is such that a rubber (front) sealing member 35 is adhered to an outer case 34 and a first sealing element 36 and a second sealing element 37 having a spiral groove are formed.
Via the first inner case 38, the washer 39, the second inner case 40, etc., into the outer case 34 (by caulking).
Assembled together.

The rubber seal member 35 has a lip tip portion 41 whose diameter gradually decreases toward the fluid storage chamber 33 side. Works. In other words, when stationary, the fluid is sealed by the pressure of the fluid storage chamber 33 and the rubber elasticity of the lip tip 41 itself.

When the rotary shaft 32 rotates around the axis L, a slight leakage occurs from the sliding contact portion between the lip tip 41 and the rotary shaft 32. However, the spiral of the first and second seal elements 36 and 37 is generated. Due to the hydrodynamic effect of the groove (screw groove), the leak is pushed back (to the left in FIG. 8), and the rotary shaft seal is entirely sealed.

[0006]

In the conventional seal described above, when the pressure in the fluid storage chamber 33 is high (the high pressure acts in the direction of arrow P in FIG. 8), the lip tip 41 becomes large. It is deformed and strongly pressed against the rotating shaft 32 to be in a surface contact state, and the contact portion of the lip tip 41 with the rotating shaft 32 {seal surface 42} is greatly worn, causing a problem of early leakage. In addition, such abrasion causes a problem that the vicinity of the seal surface 42 becomes high temperature (expected to be 200 ° C. or higher), and the rubber deteriorates due to thermal deterioration, thereby causing cracks.

The inventors tried to reduce the friction by applying a PTFE coating to the sealing surface 42 of the rubber lip tip 41. However, the PTFE was generated by the sliding friction heat between the rotating shaft 32 and the sealing surface 42. The coating agent was dissolved, and the dissolved coating agent became an abrasive, so that the rubber lip tip 41 (the sealing surface 42) was abnormally worn, and the durability was significantly reduced. Thus, it was found that the PTFE coating cannot withstand the heat friction (even though it can follow the elastic deformation of the rubber). In short, a coating agent that can follow the elastic deformation of the tip of the rubber lip, withstand heat friction, and extend the life of the rotating shaft has not been known.

Further, a gas fluid such as CO ₂ is supplied to the fluid storage chamber 33.
There is also a problem that the gas permeates and escapes from the side through the rubber (front) sealing member 35 to the low pressure side (to the right in FIG. 8), resulting in an insufficient gas filling amount.

[0009]

According to the present invention, there is provided a rotary shaft seal provided with a front seal member having a rubber lip tip portion provided on a fluid storage chamber side and slidingly contacting the rotary shaft. Further, a diamond-like carbon coating is applied to the sealing surface of the lip tip.

In a rotary shaft seal provided with a rear seal member having a rubber lip tip disposed on the low pressure side and in contact with the rotary shaft, a diamond-like carbon coating is applied to a sealing surface of the lip tip. It was done.

A front sealing member having a rubber lip tip disposed on the fluid storage chamber side and in sliding contact with the rotating shaft;
And a rear seal member having a rubber lip tip disposed on the low-pressure side and in contact with the rotating shaft.In the rotating shaft seal, the sealing surfaces of both lip tips are coated with diamond-like carbon coating. It was done.

Further, a diamond-like carbon coating may be applied to the outer peripheral surface of the rotating shaft which is in sliding contact with or in contact with the sealing surface. In addition, a diamond-like carbon coating is applied to the entire rubber surface where the front seal member contacts the sealed fluid on the fluid storage chamber side.

Further, a diamond-like carbon coating is applied to the entire rubber surface where the front seal member comes into contact with the sealed fluid on the fluid storage chamber side, and the front lip end portion of the rubber lip where the front seal member slides on the rotating shaft. The diamond-like carbon coating is applied to the sealing surface.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on the illustrated embodiments.

FIG. 1 shows a rotary shaft seal according to the present invention,
For example, it is a seal used for a car air conditioner compressor or the like in which a high-pressure refrigerant (such as CO ₂ ) acts on the fluid storage chamber 33 side. The rotary shaft seal is interposed between a housing 31 such as a compressor and the (outer peripheral surface of) the rotary shaft 32 and is used to seal a fluid such as a high-pressure refrigerant.

In FIG. 1, only half of the longitudinal section of the shaft seal is shown, and the rotary shaft 32 and the housing 31 are shown by two-dot chain lines. The shape of the rotating shaft seal is not mounted.
This shows the case of the "free state", and in a mounted state (not shown) interposed between the rotary shaft 32 and the housing 31, each part is elastically deformed and interposed.

Specifically, in FIG. 1, a metal outer case 1 having inner flange portions 2 and 3 and an outer peripheral surface of a cylindrical portion 4 of the outer case 1 and a front portion (a fluid storage chamber 33 side) are provided. A rubber front sealing member 5 fixed and integrated on the front and rear surfaces of the inner flange portion 2 by adhesion, welding, baking, etc., a sealing element 7 with a spiral groove 6, and a low pressure (atmosphere) side 45 °. Then, this direction is called “rear”.
25.

More specifically, the front support member 12 (supporting the front seal member 5), the first inner case 9, the second inner case 11, the rear support member 22 (supporting the rear seal member 25), 3 inner case 19
Is added.

The front seal member 5 is located on the fluid storage chamber 33 side.
It has a (rubber) lip portion 13 extending forward {the rubber} lip end portion 13b of the lip portion 13.
It comes into sliding contact with the outer peripheral surface of the rotating shaft 32 (during rotation). The rear seal member 25 includes a metal portion 16 having an L-shaped cross section, and a rubber portion 27 integrated with the metal portion 16 by bonding, welding, baking, or the like.
The rubber portion 27 covers the outer peripheral surface of the cylindrical portion 16a of the metal portion 16 (in a state before assembly) and has a corrugated portion having a corrugated portion.
27c, an inner flange jacket 27d (of a U-shaped cross section) that covers the inner flange 16b of the metal part 16, and a lip 27e extending continuously from the inner flange jacket 27d forward. , Consisting of The lip portion 27e includes a short cylindrical portion 27f parallel to the axis L, and a lip tip portion 27b whose diameter is reduced forward.
Has a shape similar to that of the lip portion 13.

The lip portion 27e is mainly for preventing static leakage, and fluid is stored in a pressurized state in a vacant space 28 shown by a hatched dotted line in FIG. 1 on the outer peripheral surface of the rotating shaft 32 in a stationary state. Contact (sometimes referred to as a static pressure state)
Acts as a seal.

At the rubber lip tip portions 13b and 27b of the front sealing member 5 and the rear sealing member 25 in FIG. 1, the sealing surfaces S, which slide or contact the rotating shaft 32 to perform a sealing action. S '{portion shown in small meshes in FIG. 1}
Has a diamond-like carbon coating. If desired, only one of the front and rear sealing surfaces S and S 'may be provided with a diamond-like carbon coating (hereinafter abbreviated as DLC). Further, it is desirable to apply DLC to the outer peripheral surface of the rotating shaft 32 where the rotating shaft 32 slides or comes into contact with the sealing surfaces S and S '.

DLC is applied to the entire rubber surface A (the range A shown by a dotted line in FIG. 1) where the front seal member 5 is in contact with the sealed fluid on the fluid storage chamber 33 side, and the fluid is applied. It is also preferable that the configuration is such that the permeation of a sealed fluid such as CO ₂ gas on the storage chamber 33 side is reduced or prevented. Of course, it is preferable to apply DLC to both the sealing surface S and the entire surface A.

The rubber lip tip 13 of the front seal member 5
By performing DLC on the seal surface S of FIG. 2B, the sliding friction resistance during rotation of the rotating shaft 32 can be reduced.
───Especially, the wear of the lip tip can be reduced.
Further, by performing DLC on the sealing surface S 'of the lip tip portion 27b of the rear sealing member 25, the lubrication is poor, so that the sealing surface S', which is liable to generate heat due to sliding friction, is prevented from generating heat and heat resistance is improved. be able to.

The interference of the rubber lip tip 27b of the rear seal member 25 is desirably set to zero or minus. That is, the sealing during rotation of the rotating shaft 32 is performed by the front sealing member 5 and the sealing element 7, so that the rear sealing member 25 does not need to function during rotation.
Then, in the stationary pressurized state, the tip of the lip tip portion 27b of the rear seal member 25 comes into contact with and is pressed by the rotating shaft 32, and mainly exerts a leak-preventing sealing function at rest.

As is clear from FIG. 1, the interference of the front seal member 5 is set larger than the interference of the rear seal member 25. This front sealing member 5
Serves as a main seal that functions both when rotating and when stationary.

To further explain, a front seal member 5 integrally fixed to the front half portion of the outer case 1
In order to form a sealing action by resiliently contacting the inner peripheral surface of the housing 31 (in a free state), the cylindrical covering portion 5a having the outer peripheral surface formed in a concave and convex waveform and the front and rear surfaces of the front inner flange portion 2 are formed. It comprises a U-shaped inner flange outer cover 5b to be covered, and a lip 13 protruding from the inner peripheral side of the outer cover 5b toward the fluid storage chamber 33 (front).

The lip portion 13 further includes a short cylindrical portion 13a
And a lip tip 13b that gradually decreases in diameter toward the fluid storage chamber 33 side and that inclines inwardly. The lip portion 13 is bent in a U-shaped cross section. Shape. The sealing surface S around the tip 14 of the lip tip 13b
However, in a mounted (used) state, it comes into contact (sliding contact) with the outer peripheral surface of the rotating shaft 32 to perform a sealing action.

The support fitting 12 has a substantially L-shaped cross section for supporting the rear side wall portion or the inner diameter portion of the inner flange jacket portion 5b of the front seal member 5 and the lip tip portion 13b. Behind the support fitting 12, a first inner case 9, a sealing element, a second inner case 11, a rear seal member 25, a rear support fitting 22, and a third inner case having a J-shaped cross section are sequentially arranged. The inner flange portion 3 of the outer case 1 is bent (formed) by plastic working so as to be fixed (held) between the front and rear inner flange portions 2 and 3 in a pressurized manner.

Thus, the sealing element 7
The first inner case 9 and the second inner case 11 pinch and hold. The rear seal member 25 is an inner collar
The rear surface or inner diameter surface of 27d and the inner surface side of the lip 27e are supported by the rear support fitting 22. At this time, the cylindrical portion covering portion 27c in which the outer peripheral surface is formed in an uneven waveform is press-fitted to the cylindrical portion 4 of the outer case 1 and assembled.
Sealability (sealability) is ensured, and external leakage to the low-pressure side (atmosphere side) 45 from between the outer peripheral edge of the rear seal member 25 and the inner surface of the outer case 1 can be prevented. In FIG. 1, the seal element 7 is disposed near the center in the front-rear direction (the direction of the axis L of the rotating shaft 32), and the two spaces of the front empty space 29 and the rear empty space 28 are formed. Has formed.

Further, the support fitting 12 will be additionally described. In FIG. 1, the support fitting 12 is provided with the front seal member 5.
In almost the entire area except for the vicinity of the front end 14 of the front seal member 5, the front seal member 5 comes into close contact (contact) with the rear surface or the inner surface to serve as a gas shielding member (action / function). And, as mentioned above,
When the DLC is applied to the range A (entire rubber surface) indicated by the dotted line, the same function and function of gas shielding (prevention of gas permeation) is performed, and therefore, there is an advantage that the function and function can be more reliably enhanced. That is, as the fluid in the fluid storage chamber 33, CO ₂
When a refrigerant gas having a relatively high gas permeability to rubber, such as a gas, is used, a support bracket (backup ring) 12 and a DLC for gas shielding and gas permeation prevention are used.
The role (action / function) of the coating becomes more important.

Further, as is apparent from FIG. 1, the lip tip portion 13b of the front seal member 5 is inclined with respect to the axis L of the rotary shaft 32 at a predetermined inclination angle θ (in a forward reduced diameter shape). As the inclination angle θ, 10 ° ≦ θ ≦ 45 ° is preferable. The support fitting 12 has a slope receiving surface for receiving the inclined lip tip 13b from the inner surface (rear).
12a at the front end. The inclination angle of the inclination receiving surface 12a is set to be the same as the aforementioned θ.

As described above, the slope receiving surface of the support fitting 12
12a is held in close contact with the back surface (inner surface) of the lip tip 13b to prevent excessive deformation of the lip tip 13b when receiving pressure, and exhibits excellent sealing performance (sealability) and durability. Let me. In particular, it is possible to prevent an increase in the contact area where the seal surface S including the tip end 14 is in sliding contact with the rotating shaft 32 during rotation, prevent heat generation and wear, and extend the life of the front seal member 5. In the present invention, since the DLC is applied to the seal surface S, further heat generation and wear can be prevented, and the life of the front seal member 5 can be further extended. Further, the sliding friction resistance with the rotating shaft 32 can be extremely reduced.

If the inclination angle θ is smaller than the lower limit described above, the lip tip 13b becomes (unnecessarily) long, and it is difficult to maintain line contact when the tip 14 receives pressure. Conversely, if θ exceeds the upper limit, the lip tip 13b becomes too small, making it difficult to delicately respond to an increase or decrease in the pressure in the fluid storage chamber 33, and lowering the sealing performance.

In short, the shaft seal shown in FIG. 1 is interposed between the housing 31 and the rotary shaft 32 and has a sealing element 7 (made of synthetic resin) having a spiral groove 6 and a front part of the sealing element 7. A front sealing member 5 having a rubber lip tip 13b disposed and slidingly contacting the rotating shaft 32, and a rubber lip tip 27b disposed on the low pressure side 45 and contacting the rotating shaft in a static pressurized state. A rear seal member 25 is provided. The front seal member 5 performs a sealing function during operation (during rotation) and at rest, and the rear seal member 25 is mainly for preventing stationary leakage. Further, the intermediate seal element 7 has a function of returning the fluid accumulated in the rear space 28 to the front space 29 and the fluid storage chamber 33 by the pumping action (hydrodynamic action) of the spiral groove 6 at rest. Eggplant

The material of each component will be described.
Support bracket 12, outer case 1, first, second, third
The materials of the inner cases 9, 11, 19 and the metal part 16 are metals such as steel. Further, the seal element 7 is made of a fluororesin such as PTFE, and the rubber portion 27 of the front seal member 5 and the rear seal member 25 is HLC for HLC in consideration of refrigerant resistance. Particularly preferred is J
The IS hardness is set to 87-96. (If the JIS hardness is less than 87, the deformation will be excessive, and if it exceeds 96, the elasticity will be insufficient.)

The rear seal member 25 and the rear support fitting 22 will be additionally described.
The shape and function are the same as those of the support fitting 12. That is,
The rear support fitting 22 also serves as a gas shielding member (operation and function) for a refrigerant such as CO ₂ . The structure is such that double gas shielding is performed by the front support fitting 12 and the rear support fitting 22. If DLC is applied to the front seal member 5 over the range A (entire rubber surface) indicated by the dotted line, it can be said that the structure is such that triple gas shielding (permeation prevention) is performed. Further, the lip tip 27b of the rear seal member 25
Are inclined (in a forward reduced diameter shape) at a predetermined angle θ in a range of 10 ° ≦ θ ≦ 45 °. The support fitting 22 has a gradient receiving surface 22a inclined at the same inclination angle θ at the front end, and the gradient receiving surface 22a receives the lip tip portion 27b from the rear (low pressure side). The operation and function are the same as those of the front support fitting 12, but in particular, the above-mentioned DLC was performed by preventing the sealing surface S 'of the rear sealing member 25 from strongly contacting the rotating shaft 32 during rotation. In combination with the configuration, it is possible to prevent wear of the seal surface S ', prevent heat generation, and extend the life.

Next, in another embodiment shown in FIG.
The length dimension in the direction of the axis L can be made shorter than that in FIG. That is, the first inner case 9 in FIG. 1 is omitted, so that the seal element 7 is attached to the rear surface or the inner surface of the support fitting 12 by
It is arranged. Further, the shape of the rear seal member 25 is different, the shape of the second inner case 11 is changed (accordingly), and the washer 18 is added.

The rear seal member 25 includes a (washer-shaped) metal annular flat plate portion 26, a rubber portion 27 integrated with the front side and inner peripheral edge of the flat plate portion 26 by bonding, welding, baking, or the like. Consists of The rubber portion 27 has a lip tip portion 27b (made of rubber) extending inward from the inner peripheral edge position of the flat plate portion 26 to the front.

DLC is applied to the sealing surface S 'of the lip tip portion 27b as in FIG. Since the same reference numerals as those in FIG. 1 have the same configuration, the description of the configuration and operation is omitted. In the embodiment of FIG. 2, the pressure fluctuation in the fluid storage chamber 33 easily spreads to the lip tip 27b of the rear seal member 25 because there is no front empty space 29 in FIG. Because there is no rear support bracket 22 of
Although it is conceivable that the sealing surface S 'of the lip tip portion 27b relatively slidably contacts the lip 32, the use of DLC has the advantage of reducing abrasion and heat generation during the slidable contact. is there.

Next, in another embodiment shown in FIG.
The first inner case 9 in FIG. 1 is omitted, and the seal element 7 is disposed along the rear surface or the inner surface of the front support fitting 12 to shorten the length dimension in the axis L direction. Since the same reference numerals as those in FIG. 1 have the same configuration, the description of the configuration and operation is omitted.

Next, in still another embodiment shown in FIG. 4, the support fitting 22 in the embodiment shown in FIG.
Is omitted, and the second seal element 8 is added instead. That is, the front first sealing element 7
And a total of two pieces of PTFE of the rear second seal element 8
A sealing element with a helical groove 6 made of stainless steel.
However, in the rear seal element 8, it is essential to provide a smooth contact portion (straight portion) 20 in which the spiral groove 6 does not exist.

Since the same reference numerals as those in FIGS. 1 and 3 have the same configuration, the description of the configuration and operation will be omitted. In the embodiment of FIG. 4, since the front chamber 29 of FIG. 1 is not provided, the pressure fluctuation in the fluid storage chamber 33 easily spreads to the lip tip 27b, and the rear support fitting 22 of FIG. It is expected that the sealing surface S 'of the lip tip portion 27b will relatively slidably contact the rotating shaft 32 during rotation, but the sealing surface S'
Has a merit that the wear and the heat generation during the sliding contact can be reduced.

Next, in another embodiment shown in FIG.
This is a configuration in which a second seal element 8 is added to the structure having substantially the same structure as the embodiment of FIG. 1 and the first inner case 9 of FIG. 1 is divided into a first inner case 9a and a washer 9b.

The second sealing element 8 in FIGS. 5 and 4 has the same configuration, and the function thereof is that the lip tip portion 27b of the rear sealing member 25 for preventing static leakage is subjected to minute leakage until the lip tip 27b is deformed by receiving pressure. To prevent. The above-mentioned smooth contact portion (straight portion) 20 is necessary for that purpose. Other configurations and operations in FIG. 5 are the same as those in FIG.

Next, in another embodiment shown in FIGS. 6 and 7, the rear seal member 25 (for preventing static leakage) in FIGS. 1 to 5 described above is omitted. Fluid storage room 33
The front sealing member 5 on the side, the first sealing element 7 and the second sealing element 8 perform a sealing action.

In FIG. 7, the (front) support bracket 12 is shown.
6 is different from FIG. 6 in that it is added, and the other configuration is the same. 6 and 7, DLC is applied to the sealing surface S of the front sealing member 5, and / or DLC is applied to a range A (entire rubber surface) indicated by a dotted line. Its operation is similar to that of FIG.
The sealing surface S including the tip 14 of the rubber lip portion 13 of the front sealing member 5 has a sealing function at the time of rotation as well as at rest (to prevent leakage). It is important to reduce. Other configurations in FIGS. 6 and 7 are denoted by the same reference numerals as those in FIG. Note that the outer peripheral surface of the rotation shaft 32 has a DL
C can be freely combined with any of the embodiments shown in FIGS. 1 to 7.

[0047]

According to the present invention, the following significant effects can be obtained by the above configuration.

The lip tip 13 of the front seal member 5 as the pressure-side main lip (according to claims 1, 3 and 6)
The sliding frictional resistance between the seal surface S of b and the rotating shaft 32 can be reduced, and the rotational torque loss can be reduced. In addition, the wear of the seal surface S can be reduced, and the life is extended. In particular, the fluid storage chamber 33
In a use situation in which high pressure acts on the lip tip 13b against the rotating shaft 32, wear is reduced and the sealing performance is maintained for a long time. . Further, by reducing the friction, it is possible to prevent the rubber material from being thermally degraded due to the heat generated by the conventional sliding contact of the sealing surface S.

According to the second and third aspects, the DLC is applied to the sealing surface S 'of the rubber lip tip portion 27b of the rear sealing member 25 which is poor in lubrication and easily generates heat during operation. In addition, the frictional resistance with the rotating shaft 32 is reduced, the amount of generated heat is reduced, the thermal deterioration is prevented, the life is extended, and the function of preventing leakage at rest can be maintained for a long time.

According to the third aspect, in both the operating state and the stationary state, excellent sealing performance can be maintained for a long period of time. (According to claim 4), a further lowering effect of friction, an effect of preventing heat generation, and a longer service life effect can be obtained.

According to the fifth and sixth aspects, it is possible to effectively prevent the sealed (gas) fluid such as CO ₂ from passing through the front sealing member 5 made of rubber. This solves the problem of, for example, a shortage of gas filling of a car air conditioner, and its practical effect is remarkable.

(According to claim 6) The entire rubber surface A
Since the DLC processing can be simultaneously performed over the sealing surface S and the sealing surface S, workability is good.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view showing a main part of a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of a main part showing a second embodiment of the present invention.

FIG. 3 is a vertical sectional view of a main part showing a third embodiment of the present invention.

FIG. 4 is a vertical sectional view showing a main part of a fourth embodiment of the present invention.

FIG. 5 is a vertical sectional view showing a main part of a fifth embodiment of the present invention.

FIG. 6 is a vertical sectional view of a main part showing a sixth embodiment of the present invention.

FIG. 7 is a vertical sectional view of a main part showing a seventh embodiment of the present invention.

FIG. 8 is a half sectional side view showing a conventional example.

[Explanation of symbols]

 5 Front seal member 13 Rubber lip 13b Lip tip 25 Rear seal member 27b Lip tip 31 Housing 32 Rotating shaft 33 Fluid storage chamber 45 Low pressure side (atmosphere side) A Entire surface (range of dotted line) S Seal surface S 'seal surface

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Junichi Tsujimoto 1-8-30 Tenmabashi, Kita-ku, Osaka OAP Tower Mitsubishi Cable Industries, Ltd. Kansai branch office (72) Inventor Kosuke Tsurai 1-8, Tenmabashi, Kita-ku, Osaka No. 30 OAP Tower Mitsubishi Cable Industries, Ltd. Kansai branch office F-term (reference) 3J006 AE05 AE16 CA00

Claims (6)

[Claims] In a rotary shaft seal provided with a front seal member having a rubber lip tip portion provided on a fluid storage chamber side and slidably contacting a rotary shaft, a diamond-like carbon is provided on a sealing surface of the lip tip portion. A rotating shaft seal characterized by being coated. 2. A rotary shaft seal having a rear seal member having a rubber lip tip disposed on a low pressure side and in contact with a rotary shaft, wherein a diamond-like carbon coating is applied to a sealing surface of the lip tip. A rotating shaft seal characterized by being applied. 3. A front seal member having a rubber lip tip disposed on the fluid storage chamber side and slidably in contact with the rotary shaft, and a rubber lip tip disposed on the low pressure side and in contact with the rotary shaft. A rotary shaft seal comprising a rear seal member having a diamond-like carbon coating on the sealing surfaces of both lip tips. 4. The rotary shaft seal according to claim 1, wherein a diamond-like carbon coating is applied to an outer peripheral surface of the rotary shaft that slides or contacts with the seal surface. 5. A rotary shaft seal in which a diamond-like carbon coating is applied to the entire rubber surface of a front sealing member that contacts a sealed fluid on the fluid storage chamber side. 6. A rubber-like carbon coating is applied to the entire rubber surface where the front seal member comes into contact with the sealed fluid on the fluid storage chamber side, and the front seal member has a rubber lip tip portion which slides on a rotating shaft. A rotating shaft seal characterized by a diamond-like carbon coating on the seal surface.