JP2003035367A - Seal ring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a very reliable seal ring which has creep resistance and durability and can display excellent sealing ability for a long time. SOLUTION: The seal ring 1 is made of composite material in which petroleum coke and carbon fiber are added as filler into polytetrafluoroethylene(PTFE). The petroleum coke is added so as to be 20-40 weight % and the carbon fiber is added so as to be 2-15 weight %.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seal ring for sealing an annular gap between two members.

[0002]

2. Description of the Related Art Conventionally, this type of seal ring has been used in a hydraulic system such as an automatic transmission of an automobile.

A conventional seal ring will be described below with reference to the drawings. FIG. 7 is an axial sectional view schematically showing a mounted state of a seal ring according to a conventional technique.

A seal ring 100 shown in FIG. 1 is for sealing an annular gap between a housing 200 having a shaft hole and a shaft 300 rotatably mounted in the shaft hole. Annular groove 302 provided in 300
It is used by being attached to.

The seal ring 100 is an annular member having a rectangular cross section, and a first seal surface 101 for sealing the side wall surface of an annular groove 302 provided in the shaft 300.
And the inner peripheral surface 201 of the shaft hole provided in the housing 200.
And a second sealing surface 102 for sealing

When pressure is applied in the P direction from the sealed fluid side (left side in the figure), the seal ring 100 is pressed toward the non-sealed fluid side (right side in the figure), so that the first sealing surface 101
Presses the side wall surface of the annular groove 302, and the second sealing surface 102 presses the inner peripheral surface of the shaft hole provided in the housing 200 to seal at each position.

In this way, the seal ring 100 is
While ensuring lubricity on the sealing surface, leakage of the sealed fluid to the non-sealed fluid side is prevented.

Here, the sealing fluid to be sealed by the seal ring 100 is, for example, lubricating oil, and particularly corresponds to ATF when used in an automatic transmission of an automobile.

[0009]

However, in the above-mentioned prior art, the seal ring creeps under high temperature conditions, and thereafter, the leak amount of the sealing fluid increases under low temperature conditions. There was a problem of being there.

This point will be described in detail with reference to FIG. FIG. 8 is a radial cross-sectional view schematically showing a mounted state of a seal ring according to the related art,
It shows a state when the temperature of the sealed fluid rises in the order of (b) and (c).

As shown in FIG. 1A, this type of seal ring 100 is generally provided with an abutment 103 for facilitating incorporation into the annular groove 302.
It is set so that a gap (abutment gap) of the abutment 103 is slightly generated when the sheet is mounted on the No.

The shape of the abutment 103 may be a step cut like a step, a special step cut, an oblique bias cut, etc., in addition to the straight cut shown in FIG. There is also an endless seal ring with no abutment.

When the temperature of the sealed fluid rises, the seal ring 100 thermally expands and the gap of the abutment 103 (abutment clearance) gradually narrows. When the cut surfaces of the abutment 103 are in contact with each other and the abutment clearance is zero, a good sealing property without leakage of the sealing fluid is exhibited (FIG. 7B).

However, when the temperature of the sealing fluid further rises and the expansion of the seal ring 100 increases, the abutment 103
The abutting force of the cut surface of 1 increases, and compressive stress acts on the abutment portion of the seal ring 100. When a constant load is applied at a high temperature as described above, a permanent strain occurs in the material even at a stress lower than the stress that causes plastic yielding, and the deformation of the abutment portion of the seal ring 100 progresses over time (creep). .

In this case, even if the temperature of the sealed fluid decreases next time, the shape of the creeped portion does not return to its original shape, which adversely affects the mounting state of the seal ring 100. Therefore, when operating at low temperature (for example, immediately after the start of operation in the case of an automatic transmission of an automobile), the leak amount of the sealing fluid increases, and the sealing performance deteriorates.

As a means for improving such a problem, a seal ring having the structure disclosed in Japanese Patent No. 2675579 is known. The seal ring described in the publication is made from a composition in which graphite and Ketjen black (fine carbon black powder) are mixed in polytetrafluoroethylene (PTFE) at a ratio of 25% by weight and 5% by weight, respectively. Yes, the oil absorption of carbon black aims to improve the sealing performance at low temperatures.

However, it has been pointed out that another problem arises when the carbon black is blended with PTFE. The addition of fine powder of carbon black has the drawback that the durability (wear resistance, pressure resistance) of the seal ring is reduced and the life of the seal ring is shortened.

The present invention has been made in order to solve the above-mentioned problems of the prior art. The object of the present invention is to have both creep resistance and durability and to be able to exhibit a good sealing property for a long period of time. It is to provide a highly reliable seal ring.

[0019]

In order to achieve the above object, the seal ring of the present invention is a seal ring for sealing an annular gap between two members, and polytetrafluoroethylene (PTFE) is oil coke and carbon. It is characterized by being made of a material filled with fibers.

By filling PTFE with oil coke, the creep resistance of the seal ring is improved, the creep at the time of high temperature operation can be suppressed small, and the leakage amount at the time of low temperature operation can be greatly reduced. Become.
Moreover, the durability (wear resistance and the like) of the seal ring can be secured by filling the carbon fiber.

It is preferable that the seal ring is filled with oil coke at a ratio of 20% by weight to 40% by weight.

Further, it is preferable that the seal ring is filled with carbon fibers at a ratio of 2% by weight to 15% by weight.

If the filling amount of oil coke exceeds 40% by weight, the material becomes brittle, which leads to deterioration of the assembling property and durability of the seal ring, while if the filling amount is less than 20% by weight, the resistance is low. The creep effect is too small.

Further, if the filling amount of the carbon fiber exceeds 15% by weight, the material becomes brittle and the assembling property of the seal ring is deteriorated, while if the filling amount is less than 2% by weight, the durability is deteriorated. The improvement effect of is lost.

That is, by filling the oil coke and the carbon fiber in the above proportions, it is possible to obtain a seal ring having both creep resistance, durability and assembling property as appropriate.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, the dimensions of the components described in this embodiment,
Unless otherwise specified, the material, the shape, the relative arrangement, and the like are not intended to limit the scope of the present invention thereto.

A seal ring according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 is a schematic plan view of a seal ring according to an embodiment of the present invention, and FIG. 2 is an axial sectional view schematically showing a mounted state of the seal ring.

As shown in FIG. 2, the seal ring 1 according to the present embodiment has an annular gap between two members which are provided so as to be rotatable relative to each other, that is, a housing 2 having a shaft hole, and this shaft. It is for sealing an annular gap between the shaft 3 and the shaft 3 inserted into the hole, and is used by being mounted in an annular groove 32 provided in the shaft 3.

The seal ring 1 is an annular member having a rectangular cross section, and is provided on the housing 2 and the first sealing surface 11 for sealing the side wall surface 33 of the annular groove 32 provided on the shaft 3. And a second sealing surface 12 for sealing the inner peripheral surface 21 of the shaft hole.

Further, a part of the seal ring 1 is provided with an abutment 13 for facilitating the assembling into the annular groove 32. The gap 13 is set so that a gap is slightly generated when the seal ring 1 is mounted in the annular groove 32.

In addition to the straight cut shown in FIG. 1, the shape of the abutment 13 may be a step cut, a special step cut, an oblique bias cut, or the like. Alternatively, the seal ring may be configured in an endless manner without providing a joint.

In the apparatus shown in FIG. 2, when pressure is applied in the P direction from the sealed fluid side (left side in the figure), the seal ring 1 is pressed toward the non-sealed fluid side (right side in the figure), so that the first seal. The surface 11 presses the side wall surface 33 of the annular groove 32, and the second sealing surface 12 presses the inner peripheral surface 21 of the shaft hole provided in the housing 2 to seal at each position.

When the temperature of the sealed fluid rises, the seal ring 1 thermally expands, the cut surfaces of the abutment 13 abut against each other, and the abutment clearance becomes zero.

In this way, the seal ring 1 has the first
While ensuring the lubricity of the seal surface 11 and the second seal surface 12, the leak of the sealed fluid to the non-sealed fluid side is prevented.

The seal ring 1 of the present embodiment can be widely applied to devices such as automobiles, railroad cars, ships, and other general industrial equipment. The sealing fluid to be sealed is, for example, lubricating oil,
Especially when used for automatic transmission of automobile, ATF
It is equivalent to (Automatic Transmission Fluid).

Among these devices, there are those in which the lubricating oil, which is a sealed fluid, becomes extremely high temperature and high pressure when the device is operated, and those in which the housing 2 and the shaft 3 relatively rotate at a very high speed. Therefore, the seal ring 1 is required to have various characteristics such as heat resistance, pressure resistance, wear resistance, and creep resistance.

The seal ring 1 of the present embodiment is made of a composite material in which polytetrafluoroethylene (PTFE) is filled with oil coke (petroleum coke) and carbon fiber.

PTFE is a resin excellent in heat resistance and cold resistance that can be continuously used in a wide temperature range of -200 ° C to + 260 ° C, and has a very low coefficient of friction of 0.04 to 0.3 and friction resistance. It is also excellent in sex. As the PTFE, homo-PTFE may be used, or modified PTFE partially modified
E may be used.

Oil coke is a porous solid material obtained by cracking or cracking distillation of petroleum or bituminous oil. The oil coke used as the filler has an average particle size of 10 μm to 50 μm, and more preferably 20 μm to 30 μm.

By the way, when PTFE is reinforced with a filler to form a composite material, since PTFE is not sticky and is not well compatible with the filler, if the filler is filled too much, the material becomes brittle. This leads to deterioration of the assembling property and durability of the seal ring. On the other hand,
If the filling amount is too small, the reinforcing effect (creep resistance, abrasion resistance, etc.) cannot be sufficiently obtained.

Therefore, in this embodiment, 20% by weight to 40% by weight of oil coke and 2% by weight of carbon fiber are used.
It was decided to fill at a rate of -15% by weight. As a result, it is possible to obtain a seal ring having both creep resistance and durability / installability.

As described above, by filling PTFE with oil coke, the creep resistance of the seal ring 1 is improved, and the creep during high temperature operation can be suppressed to a small level. Therefore, when operating at low temperature (for example, immediately after the start of operation in the case of an automatic transmission of an automobile), it is possible to significantly reduce the leak amount of the sealed fluid.

Further, the wear resistance of the seal ring 1 could be ensured by combining the oil coke and the carbon fiber.

As described above, according to the structure of the present embodiment, it is possible to manufacture a seal ring having both creep resistance and durability and exhibiting good sealability for a long period of time. Become.

[0046]

EXAMPLE An example based on the above embodiment will be described below. In addition, the results of a comparative test between this example and a comparative example based on the conventional configuration are shown.

FIG. 3 is a table showing the composition of this example and the compositions of Comparative Examples 1 and 2 based on the conventional structure.

The seal ring of the present embodiment is made of oil coke (produced by Chuetsu Graphite Industry Co., Ltd .: average particle size 2) as a filler for PTFE (produced by Asahi Glass Co., Ltd .: G163).
0 μm oil coke) and carbon fiber (Kureha Chemical Industry Co., Ltd .: Crecachop M-201S) are mixed in the proportions of 70% by weight, 25% by weight and 5% by weight, respectively.

The seal ring of Comparative Example 1 had a typical conventional composition, and bronze (manufactured by Fukuda Metal Foil & Powder Co., Ltd .: average particle size 10 μm) as a filler was used in comparison with PTFE (same as above). It is composed of a composite material in which carbon fibers (same as above) are blended in the proportions of 70% by weight, 30% by weight and 10% by weight, respectively.

Further, the seal ring of Comparative Example 2 has a composition substantially similar to that disclosed in the above-mentioned Japanese Patent No. 2675579, and uses PTFE (the same company) as a filler for PTFE (same as above). Chuetsu Graphite Industry Co., Ltd .: average particle size 15 μm graphite) and carbon black (Mitsubishi Chemical Co., Ltd .: Ketjen Black E)
CP600JD) in a proportion of 70% by weight, 25% by weight and 5% by weight, respectively.

A creep test, a leak test and an abrasion test were carried out for each seal ring produced by the above composition, and the results were compared.

(Creep test) The creep test was carried out at a temperature of 165 using ATF Matic Fluid D as a lubricating oil.
It was performed by examining the change in the circumferential length of the seal ring after leaving it for 12 hours in an environment of ° C.

FIG. 4 shows the circumferential length change rates of the seal rings of Examples, Comparative Examples 1 and 2. The rate of change in circumference was calculated by the following equation. That is, it can be said that the smaller the circumferential length change rate, the greater the creep under high temperature conditions and the poorer the creep resistance. Conversely, the larger the circumferential length change rate (close to 0), the smaller the creep under high temperature conditions. It can be said that it has excellent creep resistance. Perimeter change rate = (L1-L0) / L0 x 100 [%] L0: Perimeter of seal ring before heat history L1: Perimeter of seal ring after heat history

As shown in the results of FIG. 4, the peripheral length change rate of the seal ring of this example is slightly lower than that of the comparative example 2 having improved creep resistance, but from the conventional typical composition. The value is sufficiently smaller than that of Comparative Example 1.

From this, it can be seen that by filling PTFE with oil coke, the creep resistance of the seal ring is improved and the creep under high temperature conditions can be suppressed to a small level.

(Leak Test) In the leak test, ATF Matic Fluid D was used as the lubricating oil, and the oil pressure was 1.96M.
The test equipment was operated with Pa and the shaft rotation speed set to 2000 rpm, and the temperature was changed from 25 ° C. under the low temperature condition to 140 under the high temperature condition.
It was performed by gradually changing the temperature to 0 ° C. and examining the amount of leakage of the lubricating oil (leak amount) under each temperature condition.

The leakage amount of the seal ring of the example and the comparative example 2 is shown in FIG. 5 (a), and the leakage amount of the seal ring of the comparative example 1 is shown in FIG. 5 (b). In the figure, the graph shown by the solid line is
The leakage amount before the heat history, that is, in the seal ring in the initial state without creep deformation is shown, and the graph shown by the broken line shows the leakage amount in the seal ring after the heat history, that is, after the creep test. .

As can be seen from the results of FIG. 5, in the seal ring of Comparative Example 1 having a typical conventional composition, about 12 after creep deformation (after thermal history) occurred under high temperature conditions.
Where the lubricating oil leaks up to near 0 ° C., the seal ring of the present embodiment causes almost no creep even under high temperature conditions, and therefore there is almost no change in the amount of leakage before and after thermal history. That is, it can be seen that the leak amount of the sealed fluid during the low temperature operation can be significantly reduced.

(Abrasion test) The abrasion test was conducted by using A as a lubricating oil.
Using TF Matic Fluid D, at a temperature of 120 ° C, hydraulic pressure 1.96 MPa, shaft rotation speed 4000 rp
It was carried out by operating the test device continuously for 100 hours at m, and examining the amount of wear of the seal ring. The housing was made of soft nitriding SS400 and the shaft was made of carburized and quenched S35C.

FIG. 6 shows the amount of wear of each seal ring in Examples, Comparative Examples 1 and 2.

As can be seen from the results shown in FIG. 6, the seal ring of Comparative Example 2 is much less wear resistant than that of Comparative Example 1 because it is filled with carbon black. On the other hand, the seal ring of this example has the same wear resistance as that of Comparative Example 1. That is, it is understood that the wear resistance of the seal ring can be secured by using oil coke and carbon fiber as the filler.

[0062]

As described above, since the seal ring of the present invention uses the material obtained by filling polytetrafluoroethylene (PTFE) with oil coke, the creep resistance of the seal ring is improved and the seal ring during high temperature operation is improved. The creep can be suppressed to a small level, and the amount of leakage during low temperature operation can be greatly reduced.

Also, the durability (wear resistance, etc.) of the seal ring can be secured by filling the carbon fiber.

Further, 20% by weight of oil coke to 4
By filling 0% by weight and 2% by weight to 15% by weight of carbon fibers, it is possible to obtain a seal ring having both creep resistance and durability / installability.

[Brief description of drawings]

FIG. 1 is a schematic plan view of a seal ring according to an embodiment of the present invention.

FIG. 2 is an axial sectional view schematically showing a mounted state of the seal ring according to the embodiment of the invention.

FIG. 3 is a composition of a seal ring according to an embodiment of the present invention,
It is a table showing composition of a seal ring of comparative example 1 and comparative example 2 based on conventional composition.

FIG. 4 is a table showing the peripheral length change rates of the seal rings of Examples, Comparative Examples 1 and 2.

FIG. 5 is a graph showing a leak amount of each seal ring in Example, Comparative Example 1 and Comparative Example 2.

FIG. 6 is a graph showing the amount of wear of each seal ring in Example, Comparative Example 1 and Comparative Example 2.

FIG. 7 is an axial sectional view schematically showing a mounted state of a seal ring according to a conventional technique.

FIG. 8 is a schematic diagram illustrating a creep phenomenon of a seal ring under high temperature conditions.

[Explanation of symbols]

1 seal ring 11 First sealing surface 12 Second sealing surface 13 Auction 2 housing 21 Inner peripheral surface of shaft hole of housing 3 axes 32 annular groove 33 Side wall surface of annular groove

Claims (3)

[Claims] 1. A seal ring for sealing an annular gap between two members, which is made of polytetrafluoroethylene (PTFE) filled with oil coke and carbon fiber. 2. Oil coke in an amount of 20% to 40% by weight.
The seal ring according to claim 1, wherein the seal ring is filled with the seal ring. 3. The seal ring according to claim 1, which is filled with carbon fibers at a ratio of 2% by weight to 15% by weight.