JPH06129547A - Seal for rotation - Google Patents

Abstract

PURPOSE:To provide a seal for rotation, with which sealing performance is ensured even when a shaft is in a stationary state. CONSTITUTION:A seal 1 for rotation is interposed between a housing 2 and a rotation shaft member 3, while a first seal element 12 and a second seal element 10 having grooved seal rip parts 15, 16, respectively, are also provided. A sticky thin film is interposed between slidably connected surfaces 17, 18 of the grooved seal rip parts 15, 16 and the rotation shaft member 3.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a seal used for a rotary shaft.

[0002]

2. Description of the Related Art Conventionally, as a rotary seal which is used by being interposed between a housing such as a compressor of a car air conditioner and a rotary shaft member, a pair of seal elements each having a grooved seal lip portion are used as holding metal fittings. There is known a structure in which the sliding contact surfaces of the grooved seal lips are brought into pressure contact with the outer peripheral surface of the rotary shaft member so as to seal fluids such as a gaseous refrigerant and refrigerating machine oil.

[0003]

However, since the sealing element is made of a fluororesin, the rotating shaft member has never been rotated due to variations in surface roughness during manufacture. There was a risk of fluid leakage such as the above-mentioned gaseous refrigerant while not operating.

Therefore, an object of the present invention is to provide a rotary seal which can obtain a stable and reliable sealing performance in a non-rotational use state (when not in operation).

[0005]

In order to achieve the above-mentioned object, the present invention is a rotary seal interposed between a housing and a rotary shaft member, each having a grooved seal lip portion. A seal element and a second seal element are arranged side by side, and a paste-like thin film is interposed between the sliding contact surface of each grooved seal lip portion and the rotary shaft member.

[0006]

[Function] A paste-like thin film is interposed between the sliding contact surface of each grooved seal lip and the rotary shaft member to close a gap due to variations in surface roughness of the sliding contact surface, so that the unrotated state It is possible to reliably prevent fluid leakage between the sliding contact surface and the rotary shaft member when not operating.

The paste-like thin film does not adversely affect the pumping action of the grooved seal lip portions of the first and second seal elements when the rotary shaft member rotates.
The sealing performance during shaft rotation can be maintained as before.

[0008]

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

FIGS. 1 and 2 show a rotary seal according to the present invention. The rotary seal 1 is fitted on an inner surface 2a of a housing 2 such as a case of a compressor, and the housing 2 and a rotary shaft member. The fluid R, which is a liquid or a gas in the fluid storage chamber 5, is sealed by slidingly contacting the outer peripheral surface 4 of the rotary shaft member 3 which is interposed between the three and rotates in a predetermined direction.

Reference numeral 6 denotes an annular holding member made of metal or the like, and in the main body portion 6a of the holding member 6, from the low pressure 7 side toward the fluid storage chamber 5 side, a holding metal fitting 8, a rubber gasket 9, and a second seal are sequentially provided. Element 10, intermediate fitting 11, first seal element
12 and the support metal fitting 13 are attached, and the concave peripheral portion 6b of the holding member 6
An O-ring 14 is attached to.

The thin and annular first and second sealing elements 12, 10 are made of a fluorine-based resin such as tetrafluoroethylene resin (PTFE), and are grooved seals which come into sliding contact with the outer peripheral surface 4 of the rotary shaft member 3. It has lip parts 15 and 16, respectively.

The seal lips 15 and 16 have the first and second seal lips.
The inner diameter sides of the seal elements 12 and 10 are bent from the low pressure 7 side to the fluid storage chamber 5 side and mounted as an L-shape.

The grooves M of the sliding contact surfaces 17 and 18 of the seal lips 15 and 16 are formed in a spiral pitch P at equal intervals (or unequal intervals), for example, as shown in FIG.

Alternatively, as shown in FIG. 5, a plurality of grooves M are concentrically formed with a pitch P of equal intervals (or unequal intervals). Also, this independent groove M is a seal element.
A plurality may be formed at an equal pitch (or unequal spacing) with eccentricity with the axis of 12 and 10 (not shown).

The grooves M of FIGS. 4 and 5 are appropriately combined to form the concentric grooves M of FIG. 5 in the first sealing element 12 and the spiral grooves M of FIG. 4 in the second sealing element 10. Or vice versa.

As shown in FIG. 2, the groove M reaches a depth approximately half the thickness of the first and second sealing elements 12, 10.
It is inclined with respect to the sliding contact surfaces 17 and 18.

Further, as shown in FIG. 3, a paste-like thin film S is interposed between the sliding contact surfaces 17 and 18 of the grooved seal lip portions 15 and 16 and the rotary shaft member 3 to seal and rotate. Fluid R (especially gas) leaks between the sliding contact surfaces 17 and 18 and the outer peripheral surface 4 of the rotating shaft member 3 even in a non-rotating use state in which the shaft member 3 is not rotated yet ─── Prevent.

Specifically, in this paste-like thin film S, the weight ratio of NBR (nitrile butadiene rubber) having an acrylonitrile content of 20 to 35% to the organic solvent (toluene, methyl ethyl ketone, etc.) is 5 to 10%. It is made of rubber glue such as NBR, which is a ratio. This is applied to the respective sliding contact surfaces 17 and 18 and is interposed between the outer peripheral surface 4 of the rotary shaft member 3.

The NBR type rubber glue has excellent airtightness and coating workability on the sliding contact surfaces 17 and 18, and has an advantage that the present invention can be carried out easily and at low cost.

Therefore, the first and second sealing elements 1
The sliding contact surfaces 17 and 18 of the rotary shaft members 2 and 10 are connected to each other via the thin film S.
When the groove M is pressed against the outer peripheral surface 4, the cross-sectional shape of the groove M expands into an acute triangular shape, and the bottom of the groove M inclines from the fluid storage chamber 5 side to the low pressure 7 side.

At this time, as shown in FIG. 3, the first and second
The contact surface pressures on the rotary shaft member 3 by the sliding contact surfaces 17 and 18 of the seal elements 12 and 10 are sharp as shown by the broken line T, and reliably prevent the fluid R from entering the low pressure 7 side.

Further, in the spiral groove M shown in FIG.
Even if the fluid R enters the groove M, the rotation of the rotary shaft member 3 causes a rotating rotation flow due to the viscosity of the fluid R to be generated from the low pressure 7 side toward the fluid storage chamber 5 and pushed back to the low pressure 7 side. The leakage of the fluid R can be reliably prevented. That is, the fluid is pushed back by the so-called screw pumping action.

On the other hand, since the above-mentioned PTFE is inactive, this PTFE is used as the first and second sealing elements 12, 10
When used as a thin film S, a paste-like body such as the above-mentioned rubber paste,
Although the adhesive force with the sliding contact surfaces 17 and 18 is small, the pasty material has a groove M.
Even if it enters into and is subjected to a shearing force when it is attached to the rotary shaft member 3, it does not peel off and remains.

It should be noted that even if a paste-like material such as rubber paste is carbonized in the groove M during the rotation of the rotary shaft member 3, the pumping action is not adversely affected and the sealing performance is not deteriorated. It was confirmed by the sealing performance test of the conventional seal (that is, the seal without the thin film S interposed) and the seal of the present invention performed under the conditions. The test results are shown in Table 2.

[0025]

[Table 1]

[0026]

[Table 2]

Next, Table 3 shows the result of the airtightness performance test when the shaft is stationary by the conventional seal. Here, the constant pressure airtight test result is that the container equipped with the seal is submerged in water,
Presence of gas leak from the pressure vessel when pressurizing this container with N ₂ gas up to the test pressure (50 kgf / cm ² ) and holding for 3 minutes, and gas leak time (up to 50 kgf / cm ²⁾ If it occurs, the pressure and time are indicated.

Further, the rapid pressurization airtightness test result shows the presence / absence of gas leakage when the pressure is increased from atmospheric pressure to the test pressure in 2 to 3 seconds, and the pressure when gas leakage occurs.
Further, the rapid depressurization airtightness test result shows the presence or absence of gas leakage when the pressure is reduced from the test pressure to atmospheric pressure in about 1 second, and the pressure when gas leakage occurs.

Each sample (seal) was used in a non-rotated state and never brought into sliding contact with the rotating shaft, and a refrigerating machine oil was applied to each sample.

[0030]

[Table 3]

Table 4 shows the results of the airtightness performance test when the shaft is stationary when the seal structure of the present invention is obtained by interposing the pasty thin film S on the sample (seal) in which gas leakage has occurred in the test of Table 3. ing.

[0032]

[Table 4]

As described above, the seal of the present invention does not cause any gas leakage in any airtight test, and is superior to the conventional seal in the airtight performance in the non-rotating use state (when not in operation). Recognize.

[0034]

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

After the seal of the present invention is installed, the rotary shaft member 3
The rotating shaft member 3 is excellent in its airtightness in the state before being rotated and used ───when not operating.
The sealing function characteristics are not affected even when rotating.

The sliding contact surfaces 17 of the grooved seal lip portions 15 and 16,
Since it is only necessary to interpose the paste-like thin film S between 18 and the rotary shaft member 3, workability is excellent, and implementation is easy and the cost is low.

[Brief description of drawings]

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

FIG. 2 is an enlarged cross-sectional view of a rotary seal.

FIG. 3 is an explanatory view of the action of a seal element.

FIG. 4 is a development view of the seal element when the groove is formed in a spiral shape.

FIG. 5 is a development view of a seal element when grooves are formed concentrically.

[Explanation of symbols]

 2 Housing 3 Rotating shaft member 10 Second seal element 12 First seal element 15 Seal lip with groove 16 Seal lip with groove 17 Sliding contact surface 18 Sliding contact surface S Thin film

Claims (1)

[Claims] 1. A rotary seal interposed between a housing and a rotary shaft member, wherein a first seal element and a second seal element each having a grooved seal lip portion are arranged side by side, and each groove is provided. A rotary seal characterized in that a paste-like thin film is interposed between the sliding contact surface of the seal lip portion and the rotary shaft member.