JP2002257243A - U-shaped seal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a U-shaped seal which is easy to be mass-produced using a few processes, and reduced in loss of materials and cost and superior in heat resistance and a sealing property. SOLUTION: In this U-shaped seal which has a recessed groove 4 and is made of a polyamide resin, the thickness of corner parts 12 and 13 at both ends of a bottom part 4a of the recessed groove 4 is larger than thicknesses T6 and T7 of the internal and external lip parts 6 and 7 from a bottom wall 1 toward a tip part. It is desirable that nonanediamine-terephthalic acid copolymer be used as the polyamide resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a high temperature, a low temperature, a high temperature, a low temperature, a high temperature, a low temperature, a high temperature, a high temperature, a high temperature, a high temperature, a high temperature, and a high temperature, in which a rubber seal cannot be used in oil, pneumatic equipment, compressors, semiconductor equipment. The present invention relates to a U-shaped seal used under severe conditions such as in the presence of steam, and more particularly to a sliding seal for rotating or reciprocating.

[0002]

2. Description of the Related Art Conventionally, pneumatic devices, compressors,
In semiconductor devices and the like, there is a seal ring having a U-shaped cross section as a hydraulic seal. As such a sealing material, polytetrafluoroethylene (PTFE), which is a kind of fluororesin, is used because it is excellent in chemical resistance, heat resistance, low friction properties, mold release properties, and the like.

[0003] For example, as a specific material composition using PTFE, while reducing the decrease in tensile strength and elongation,
Fluororesin-based sealing material made of PFA-modified PTFE, hard copper alloy powder, and glass fiber with improved creep resistance (JP-A-9-324091), ethylene tetrafluoride with improved creep resistance and dimensional stability There has been known a tetrafluoroethylene resin-based sealing material (JP-A-11-80481) in which a phenolic resin obtained by curing a resin and a prepolymer containing a reactive methylol group is blended.

However, since PTFE itself has a high melt viscosity, it is difficult to process it by melt processing such as injection molding or the like, and it is desirable that the PTFE be processed through many steps such as preforming, firing and processing by a machine such as a lathe and a milling machine. Seal products cannot be manufactured. That is, P
When TFE is used as a material for the seal ring, there are problems that the number of manufacturing steps is large and mass production is not easy, and that a large amount of material is lost due to machining by a machine, which leads to an increase in cost.

[0005] Therefore, mass production is easy even with a small number of processes.
And for the purpose of reducing the loss of material, a seal ring made of molten fluororesin having a U-shaped groove in cross section,
At least one of the two upper ends of the groove has a PTFE-based seal ring provided with an overhang toward the inside of the groove and along the circumferential direction of the seal ring ( JP-A-11-108193).

[0006] However, even with the above seal shape, the melt viscosity is high due to the characteristics of the molten fluororesin itself, the moldability and dimensional stability are poor, and a corrosive gas is generated during molding. There is still a problem that it is necessary, and it is an expensive material in terms of material cost and cannot be manufactured at low cost.

Therefore, the present inventors focused on a polyamide resin as another material, produced a prototype of the same, and repeated the experiment. However, as a seal for a compressor, a water-absorbing material for absorbing moisture in refrigerating machine oil was used. I found that there was a problem with the high rate. Alternatively, the cross-sectional shape of the seal
In particular, it has been found through trial and error that a problem such as a crack (crack) occurs depending on the shape and the thickness ─── of the bottom wall portion.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a U-shaped seal which can be easily mass-produced, has less loss of material, and has excellent heat resistance. Another object of the present invention is to provide a seal which can be used particularly for a compressor, is resistant to cracks (cracks) in the bottom wall of the U-shaped seal, and has excellent durability.

[0009]

Therefore, a U-shaped seal according to the present invention is a U-shaped seal made of a polyamide resin having a concave groove, wherein both corners of a bottom wall corresponding to the bottom of the concave groove are provided. The thickness of the portion was set to be larger than the thickness of the inner lip portion and the outer lip portion provided to extend from the bottom wall in the opening direction of the concave groove.

Further, the bottom wall of the U-shaped seal made of the polyamide resin having the concave groove has a shape which can be in close contact with the inner end surface of the concave groove for mounting of the U-shaped seal. The outer corners of the corners at both ends of the bottom wall, which can be in close contact with the inner end surface of the concave circumferential groove, are each at a right angle. The polyamide resin is made of a nonanediamine-terephthalic acid copolymer having a melting point of 300 ° C to 315 ° C. In addition, a rotary sliding seal in which the inner lip portion slides on the rotating shaft, and a pressing force in which the outer lip portion presses on the inner peripheral surface of the mounting concave circumferential groove is used for pressing the inner lip sliding on the rotating shaft. It was set to be larger than the force.

[0011]

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

FIG. 1 is a sectional view showing an embodiment of a U-shaped seal according to the present invention, FIG. 2 is an enlarged view thereof, and FIG. 1, 2, and 3, the seal S has a bottom wall 1 such that the cross-sectional shape is U-shaped.
And an inner lip portion 6 and an outer lip portion 7 extending from the bottom wall 1 in a substantially C-shape.

More specifically, the seal S
As shown in FIG. 3, the mounting concave peripheral groove 10 formed in the hole 9 of the mounting member 8 such as a housing, a casing, and a head.
The inner lip portion slides on the outer peripheral surface of the rotating shaft 11. In FIG. 3, the seal S is shown in a free state by a solid line, and the concave circumferential groove 10 and the rotating shaft 11 are shown by a two-dot chain line in order to show dimensions and relative positional relationship.

The inner lip portion 6, the bottom wall 1, and the outer lip portion 7 form a (U-valley) concave groove 4. The concave groove 4 side (upper side in FIG. 3) is formed. It corresponds to the high pressure side (the sealed fluid storage chamber side). On the other hand, the back surface 1a side of the bottom wall 1１
The lower side of FIG. 3 corresponds to the atmosphere side or the low pressure side. The back surface 1a of the bottom wall 1 is
Shape that can be in close contact with the low pressure side (atmosphere side) inner end face 10a.
That is, it is formed on the flat surface ───.

Further, both ends on the inner and outer diameter sides of the bottom wall 1 are provided.
The outer surface corners of the corners 12 and 13 are each a right angle. FIG.
As shown in the figure, the thickness of the corners 12 and 13 at both ends of the bottom wall 1
Each, T₁₂, T₁₃And inner lip 6, outer lip
7 with T₆ , T₇And the thickness of the bottom wall 1 is T₁ 
Then T₁₂> T₆ , T₁₂> T₇ , T₁₃> T₆ , T ₁₃
> T₇ , And T₁ > T₆ , T₁ > T₇ Like, set
I do. In other words, the bottom wall corresponding to the bottom 4a of the groove 4
1. Thickness T of corners 12, 13 at both ends₁₂, T₁₃Is the bottom wall 1
The inner lip 6 and the outer lip 6
Thickness T ₆ , T₇ Set to a greater than reinforced thickness
It has a meat part. Note that T₇ = T₆ And the case
1 to 3 show examples, but as described later, the outer lid
The pressing force (elasticity) of the lip portion 7 is
T) to set larger than₇ > T₆ Toss
Is desirable.

By setting the thickness T ₁ of the bottom wall 1 to be larger than the thicknesses T ₆ and T ₇ of the inner lip portion 6 and the outer lip portion 7, the thicknesses T ₁₂ and T ₁₂ of the corner portions 12 and 13 are set. T ₁₃ becomes sufficiently larger permit, inside and outside lip 6,7 when pressure is then ─── deformed as ─── root around the corner 12, 13, that the cracking and cracks are generated, effectively Can be prevented.

In the other embodiment shown in FIG. 4,
The thickness is set such that T ₁ = T ₆ = T ₇ . Also at this time, the thicknesses T ₁₂ and T ₁₃ of the corner portions 12 and 13 are set to be larger than the thicknesses T ₆ and T ₇ of the inner and outer lip portions 6 and 7, respectively, as shown in FIGS. Is the same as

Next, in FIG. 1 to FIG. 3 or FIG. 4, as described above, the outer surface corners of both end corners 12 and 13 are formed at right angles (90 °). Toward the lower pressure (atmosphere) of the inner peripheral surface 14 and the lower pressure (atmosphere) of the outer peripheral surface 15,
Axis L ₀ parallel to the straight portion (parallel portion) 16, 17 to the respective formation, the ends of the straight portions (parallel portions) 16, 17 (end point), with respect to the axis L _0, each of the inclined The angles α and β form the slope portions 18 and 19 having a angle of 5 ° to 20 °, and the inner peripheral surface of the inner lip portion 6 and the outer peripheral surface of the outer lip portion 7 are formed in a bent line shape. And, on the inner surface of the concave groove 4, this gradient portion 18,
19 are provided with parallel slope portions 21 and 22, respectively, so that the thickness T ₆ ,
It is formed in a substantially constant T _7. In addition, the inner and outer lip parts 6,
The pressure-receiving-side end surfaces (lip tip surfaces) 6a and 7a of the back surface 7a
It parallel ─── i.e., in the axis L ₀ orthogonal planar ───, is formed.

As can be seen in FIG. 2, the back of the inner lip 6
The height from 1a is h₁ From the back 1a of the outer lip 7
Height is h_Two , From the back 1a of each of the straight sections 16, 17
Is the height (length dimension) of h_Three , H_Four Then h_Two > H
₁ , And h_Four > H_Three > 1 / 3h ₁ Set as follows. Ma
The inner diameter of the straight part 16 is D₁₆And the outer diameter of the rotating shaft 11
To D₁₁Then, 0.1 mm <(D₁₆-D₁₁) <0.5mm
To the gap 23 shown in FIG.
The deformation (biting) of the part 12 is prevented.

By setting h ₂ > h ₁ , the pressure receiving area of the outer lip portion 7 (on the side of the concave groove 4) can be reduced to that of the inner lip portion 6 (the concave groove 4 side).
Larger than the pressure receiving area (on the side) (shown in FIG. 3)
The pressing force (pressing force) of the outer lip portion 7 on the inner peripheral surface 10b of the concave groove 10 is larger than the pressing force (pressing force) of the inner lip portion 6 on the outer peripheral surface of the rotating shaft 11. Set it up,
The problem that the seal S rotates together with the rotation of the rotating shaft 11,
Effectively prevent.

Further, by setting h ₃ <h ₄ , the elastic force of the outer lip portion 7 in the outer diameter direction is increased, and
The above problem of co-rotation is prevented. At this time, if T ₇ > T ₆ (not shown), the effect that the resilience of the outer lip portion 7 in the outer diameter direction is further increased and the co-rotation problem can be further expected can be expected.

5 ° ≦ α ≦ 20 ° and 5 ° ≦ β ≦
The reason for setting the angle at 20 ° is that if it is less than the lower limit, satisfactory sealing allowance (tightening allowance) will not be obtained and the sealing property will be uneasy. Conversely, if it exceeds the upper limit, the deformation at the time of mounting will be excessive. , Creeping and cracking.

Incidentally, both end corners 12, 13 of the bottom wall 1
The thickness of the T _12, T ₁₃ is the thickness of the inner and outer lip portion 6, 7 T _6,
Than either T _7, greater has been already mentioned,
T ₁₂ and T ₁₃ are set to 1.1 times to 2 times of T ₆ and T ₇ , and preferably, 1.3 times to 2 times.

Incidentally, a polyamide resin is used as the material of the seal S according to the present invention having such a shape and dimensions. Thereby, the U-shaped seal can be melt-processed by injection molding or the like. That is, in the conventional U-shaped seal made of a PTFE material, the thickness of the corners at both ends of the bottom of the groove of the U-shaped seal is reduced from the bottom of the groove toward the tip in view of material cost and ease of manufacturing. The thickness of the parts was the same. The polyamide resin used in the present invention is applied as it is to a conventional U-shaped seal (see FIG. 6).
Since the corners at both ends of the bottom wall of the U-shaped seal may be deformed and broken as shown by the dotted line in FIG. 7 at the time of pressurization, in the present invention, in the configuration detailed in FIGS. Could be prevented.

[0025] For example, the seal S of the present invention, since the back surface 1a of the bottom wall 1 is flat surface (planar), the concave peripheral groove 10 of the mounting member 8 (the axis L ₀ and perpendicular direction) in the end face 10a is closely contacted, and is not greatly deformed like the inner and outer lip portions 6 and 7, whereby the sealing performance and durability can be improved. Further, since the outer surface corners of the corners 12 and 13 are perpendicular to each other, they match the corners of the concave circumferential groove 10, and effective sealing performance and durability can be obtained.

The polyamide resin that can be used in the present invention has a melting point at which melt processing such as injection molding is possible, and preferably has a melting point of 250 ° C. to 350 ° C. Particularly preferred are those having a melting point between 300 ° C and 315 ° C.

As such a polyamide resin, known ones can be used. For example, the polyamide resin in the present invention has an acid amide bond (—CONH—) in the molecule. Polymer or copolymer obtained from caprolactam, 6-aminocaproic acid, ω-enantholactam, 7-aminoheptanoic acid, 11-aminoundecanoic acid, 9-aminononanoic acid, α-pyrrolidone, α-piperidone, etc .: hexamethylenediamine Polymers or copolymers obtained by polycondensation of diamines such as nonamethylenediamine, undecamethylenediamine, dodecamethylenediamine and meta-xylylenediamine with dicarboxylic acids such as terephthalic acid, isophthalic acid, adipic acid and sebacic acid Combined or blends thereof can be exemplified, It is not limited to these.

Examples of polyamide resins include polyhexamethylene adipamide (nylon 66), polyhexamethylene azelamide (nylon 69), polyhexamethylene sebasamide (nylon 610), and polyhexamethylene dodecanoamide (nylon 610). Nylon 612), poly-bis- (p-aminocyclohexyl) methandodecanamide, polytetramethylene adipamide (nylon 46) or polyamides resulting from ring opening of lactams; ie, polycaprolactam (nylon 6), and polylauryl lactam. . In addition, at least 2
Polyamides produced by the polymerization of various amines or acids, such as polymers produced from adipic acid, sebacic acid, and hexamethylene diamine, can be used. Blends of polyamides, such as blends of nylon 66 and nylon 6, include copolymers such as nylon 66/6.

Particularly preferred polyamide resins are a dicarboxylic acid component in which 60 to 100 mol% of the dicarboxylic acid component is terephthalic acid, and a 60 to 100 mol% of the diamine component in 1,9-
A polyamide resin comprising a diamine component that is nonanediamine and having a [n] of 0.4 to 3.0 dl / g measured in concentrated sulfuric acid at 30 ° C. Of the dicarboxylic acid components used, the terephthalic acid component is at least 60 mol%, preferably at least 75 mol%, more preferably at least 90 mol%.
When the terephthalic acid component is less than 60 mol%, various properties such as heat resistance, chemical resistance, and abrasion resistance of the obtained polyamide tend to decrease.

Other dicarboxylic acid components other than the terephthalic acid component include malonic acid, dimethylmalonic acid, succinic acid, glutaric acid, adipic acid, 2-methyladipic acid,
Aliphatic dicarboxylic acids such as trimethyladipic acid, pimelic acid, 2,2-dimethylglutaric acid, 3,3-diethylsuccinic acid, azelaic acid, sebacic acid and suberic acid;
Alicyclic dicarboxylic acids such as cyclopentanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid; isophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid; 4−
Phenylenedioxydiacetic acid, 1,3-phenylenedioxydiacetic acid, diphenic acid, dibenzoic acid, 4,4'-oxydibenzoic acid, diphenylmethane-4,4'-dicarboxylic acid, diphenylsulfone-4,4'- Examples thereof include an aromatic dicarboxylic acid such as dicarboxylic acid and 4,4′-biphenyldicarboxylic acid, or an arbitrary mixture thereof. Of these, aromatic dicarboxylic acids are preferably used. Furthermore, polyvalent carboxylic acids such as trimellitic acid, trimesic acid, and pyromellitic acid can be used within a range where melt molding is possible.

As the diamine component used in the polyamide resin of the present invention, the 1,9-nonanediamine component is at least 60 mol%, preferably at least 75 mol%, more preferably at least 90 mol%. When the composition of the diamine component is in this range, the resulting polyamide is excellent in all of heat resistance, moldability, chemical resistance, low water absorption, light weight, mechanical properties, and sliding properties.

More specifically, the melting point is 300 ° C.
Particularly preferred is a polyamide resin comprising a nonanediamine-terephthalic acid copolymer at 315 ° C., sold by Kuraray Co., Ltd. as “PA9T” and having a nominal melting point of about 308.
° C. The reason why “PA9T” is desirable is as follows. When the seal S of the present invention is used for a compressor, the water absorption is low, and it is possible to prevent moisture from entering the compressor. Excellent heat resistance. That is, the melting point is between 300 ° C and 315
° C, and the load deformation temperature (4.6 kgf / cm ² ) is 263 ° C. Therefore, the deformation at high temperature is small as the seal S,
The tight width of the sealing surfaces of the inner and outer lip portions 6, 7 can be maintained. Excellent toughness. In other words, the Izod impact strength is as large as 7.9 kg · cm / cm, so that it can be prevented from being cracked at the time of mounting on the concave circumferential groove 10 or by (pressure) impact due to pressure fluctuation. Excellent dimensional stability. That is, since the water absorption rate is low, the dimensional change due to water absorption is small, and the dimensional change at the time of heating is small (the thermal expansion coefficient is low). As a result, a uniform sealing surface pressure is obtained, and the sealing performance is improved. Excellent oil and chemical resistance. Furthermore, even if it is in contact with a refrigerant or a refrigerating machine oil at a high temperature for a long time, it hardly deteriorates.

Other diamine components other than the 1,9-nonanediamine component include ethylenediamine, propylenediamine, 1,4-butanediamine, 1,6-hexanediamine, 1,8-octanediamine, and 1,10-decanediamine. ,
1,12-dodecanediamine, 3-methyl-1,5-pentanediamine, 2,2,4-trimethyl-1,6-hexanediamine, 2,4,4-trimethyl-1,6-hexanediamine, 2
-Methyl 1,8-octanediamine, 5-methyl-1,9-
Aliphatic diamines such as nonanediamine; alicyclic diamines such as cyclohexanediamine, methylcyclohexanediamine, isophoronediamine; p-phenylenediamine, m-phenylenediamine, xylenediamine, 4,4 ′
Aromatic diamines such as -diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, and 4,4'-diaminodiphenylether, and any mixtures thereof. Among them, 2-methyl-1,8-octanediamine is preferred.

The polyamide resin of the present invention is preferably such that at least 10%, more preferably at least 40%, and even more preferably at least 70% of the terminal groups of the molecular chain have an amino group at the terminal of the polyamide such as a monocarboxylic acid or a monoamine. Alternatively, it is desirable to be sealed with a terminal blocking agent which is a monofunctional compound reactive with a carboxyl group. By performing end capping, it is possible to obtain a molding material having further excellent properties such as melt stability and hot water resistance.

The polyamide resin used in the present invention contains known compounding materials such as reinforcing materials such as glass fiber and graphite, lubricants, antioxidants, processing aids, etc., so long as the object of the present invention is not impaired. May be added.

The U-shaped seal in the present invention may be formed by a known method such as injection molding, compression molding, or extrusion molding, but the injection molding method is preferable from the viewpoint of easy production.

Hereinafter, examples and comparative examples of the invention will be described. Nonanediamine-terephthalic acid copolymer (PA9T manufactured by Kuraray Co., Ltd.) as a polyamide resin
The nozzle temperature is 320 ° C to 340 ° C, the cylinder temperature is 290 ° C to 330 ° C at the front, 280 ° C to 320 ° C at the center, and 27 at the rear.
Injection molding is carried out under the conditions of 0 ° C to 310 ° C and mold temperature of 100 ° C to 140 ° C, width 10mm, length 100mm, thickness 3mm
oInjection molding of plate material, thickness 2.8mm, diameter 6.2mm
And a U-shaped seal S having the shape shown in FIGS. 1 to 3 were produced.

The various characteristic tests were measured by the following methods. (1) Tensile strength Tensile strength was measured based on ASTM D1457. (2) Compressive strength (10% strain) Compressive strength (10% strain) based on ASTM D695
Was measured. (3) Load deformation ratio The load deformation ratio was measured under the condition of 14 Pa × 24 hours based on ASTM D621. (4) Abrasion coefficient Abrasion coefficient was measured for the above test pieces. The wear coefficient was measured using FC200 defined by JIS G5501 as a mating material, pressure P = 1.5 MPa, speed V = 3.
10m / min, 90 hours under lubrication with refrigerator oil for 72 hours
The test was carried out at 0 ° C. using a rotary dynamic wear tester. (5) Amount of wear Under the same conditions as in (4) above, the amount of wear after the test piece was worn for 72 hours was measured.

(6) Bench Durability Test A bench durability test was performed on the U-shaped seal prepared above. The test conditions are as follows. Test pressure: 1.5 MPa Rotation speed: 5500 rpm Oil used: Refrigerator oil Oil temperature: 90 ° C Test time: 200 hours

Next, as a comparative example, 10% by weight of carbon fiber
For the compounded PTFE resin composition, a test piece and a U-shaped seal having the same shape and dimensions were prepared and tested in the same manner as in the example. The results are shown in Table 1 together with the examples.

[0041]

[Table 1]

From Table 1 above, it can be seen that the product of the present invention (Example)
It can be seen that the sample exhibits excellent sealing properties and durability.

Next, FIGS. 5 to 9 show a plurality of comparative examples.
In comparison with these comparative examples, the effects and advantages of the U-shaped seal S of the present invention shown in FIGS. 1 to 3 and 4 will be described. First, the materials shown in FIGS. The same "PA9T" as the above-mentioned embodiment (example) of the present invention is used, but in the comparative example shown in FIG. 5, the bottom wall 28 has the same thickness as the inner lip portion 26 and the outer lip portion 27, and has both ends. Corner 29, 30
Have the same thickness.

[0044] In the seal S ₅ Comparative example of FIG. 5, the deformation when mounted upon and pressing the concave peripheral groove (pressure), to generate cracking (cracking) at both end corner portions 29, 30. In contrast,
In the product (embodiment) of the present invention, T ₁₂ > T ₆ , T ₁₂ > T
₇ , T ₁₃ > T ₆ and T ₁₃ > T ₇ (see FIG. 2), the strength of the corner portions 12 and 13 is sufficiently large, and no crack (crack) occurs.

Next, the seal S ₆ of the comparative example of FIG. 6 is a cross-sectional shape is curved U-shaped (with cup-shaped rounding) is uniformly set the seal the thickness. When the comparative example of FIG. 6 is mounted in the concave circumferential groove 10 as shown in FIG. 7, the state of the concave circumferential groove 10 changes from the free state shown by the solid line to the state shown by the one-dot chain line.
The bottom wall 31 contacts (partially) the inner end face 10a.
(That is, as in the embodiment of the present invention shown in FIG.
Not fully adhered to 10a. )

When the pressure is increased (pressurized) from the state shown by the one-dot chain line in FIG. 7, the corner portions 29 and 30 are greatly deformed (to conform to the shape of the concave circumferential groove 10) as shown by the broken line. Due to such a large deformation (composed of polyamide resin)
Seal S ₆ yields a crack (crack) Z (see FIG. 6).

On the other hand, in the embodiment (embodiment) of the present invention, the back surface 1a of the bottom wall 1 is in close contact with the inner end face 10a of the concave circumferential groove 10 from a low pressure state, and the corner portions 12, 13 at both ends are at right angles. 6 and FIG. 7, even if the pressure is increased (pressurized), the bottom wall 1 is not slightly deformed even if the pressure is increased (pressurized). cracks (crack) Z such as seal S ₆ of
Does not occur.

Next, the seal S _{8 of the} comparative example shown in FIG.
In order to prevent the occurrence of cracks Z of the seal S ₆ described in FIG. 6 and FIG. 7, but is obtained by increasing the thickness evenly,
In the case of polyamide resin, the rigidity is too high and it is difficult to mount it in the concave circumferential groove. Also, even if it can be mounted, the lip surface pressure becomes too high and the sliding resistance with the rotating shaft is increased. Is excessive.

On the other hand, in the embodiment of the present invention, the distribution of the thickness is carefully considered, the mounting to the concave circumferential groove 10 is easy, and the surface pressure of the inner and outer lip portions 6 and 7 is also appropriate. This has the advantage that the sliding resistance with the rotating shaft 11 is small.

Next, the seal S as shown in the comparative example of FIG.
_{In 9} , the intermediate ridges 35 and 36 are formed on the opposite side of the concave groove 37, respectively, so that the shapes of the inner and outer seal lips 33 and 34 are the maximum thickness in the middle. Also, the inner surface forming the concave groove 37
38 and 39 are also parallel to the axis. With such a shape,
There is a problem that the mold for injection molding becomes complicated, and it becomes difficult to take out a molded product, resulting in poor moldability.

On the other hand, the embodiments of the present invention have the advantage that they are excellent in moldability and can be mass-produced at low cost.

[0052]

According to the present invention, the following effects can be obtained by the above-described configuration. According to the first aspect of the present invention, mass production can be performed at a low cost with a small number of steps by a melt processing such as injection molding. Moreover, cracks (cracks) at the corners 12 and 13 at both ends
Can be effectively prevented.

The back surface 1a of the bottom wall 1 (according to claim 2)
Is always stable under any pressure receiving condition from low pressure to high pressure, and is in close contact with the inner end face 10a of the concave circumferential groove 10. Therefore, when the pressure changes from low pressure to high pressure (see the comparison shown in FIGS. 6 and 7). examples of the seal S ₆ as is apparent from the comparison with) since hardly deformed, there is no risk of cracking (cracking), excellent durability. In addition, since the posture of the seal S in the concave circumferential groove 10 is always stable, the sealing performance is also improved.

(According to claim 3) corner portions 12, 13
Is right-angled, so that the deformation at the time of pressurization (pressure-receiving) is further reduced, corresponding precisely to the right-angled shape of the corner of the concave circumferential groove 10,
Cracks (cracks) can be more reliably prevented.

(According to claim 4) As a seal for a compressor having low water absorption, it is possible to prevent water from entering into the compressor, which is advantageous. In addition, it has excellent heat resistance, little deformation at high temperatures, and does not change the state of adhesion of the sealing surface, and constantly exhibits stable sealing performance (sealing performance). Furthermore, it is excellent in toughness, and does not generate cracks. Further, since the water absorption is low, the dimensional stability is excellent, so that the sealing property (sealing property) can be further maintained. Moreover, it has excellent oil and chemical resistance and is hardly deteriorated.

(According to claim 5) the seal is provided on the rotating shaft 11
Can be effectively prevented from rotating together with a simple configuration. Thereby, abnormal wear of the outer lip portion 7 can be prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part showing one embodiment of the present invention.

FIG. 2 is an enlarged view of FIG.

FIG. 3 is a partial cross-sectional explanatory view for explaining a use state.

FIG. 4 is a cross-sectional view of a main part showing another embodiment.

5 is a cross-sectional view showing a seal S ₅ of the comparative example.

6 is a sectional view showing a seal S ₆ of the comparative examples.

7 is a sectional view showing a seal S ₆ of the comparative examples.

8 is a sectional view showing a seal S ₈ of the comparative example.

9 is a sectional view showing a seal S ₉ of the comparative example.

[Explanation of symbols]

1 bottom wall 4 grooves 4a bottom 6 inside the lip portion 7 outer lip portion 10 concave peripheral groove 10a in the end face 11 rotating shaft 12, 13 corner portion T _1, T _6, T _7, T _12, T ₁₃ thickness

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Aoshiba 663 Minoshima, Arita City, Wakayama Prefecture Mitsubishi Cable Industry Co., Ltd.Minoshima Works Co., Ltd. F-term in Mishima Works (reference) 3J006 AB01 AE15 AE39 CA03

Claims (5)

[Claims] 1. A U-shaped seal made of a polyamide resin having a concave groove, wherein the thickness of both end corners of a bottom wall corresponding to the bottom of the concave groove is from the bottom wall in the opening direction of the concave groove. A U-shaped seal characterized by being larger than the thickness of an inner lip portion and an outer lip portion provided in a stretched shape. 2. The U-shaped seal formed of a polyamide resin having the concave groove, wherein the bottom wall has a shape capable of closely adhering to the inner end face of the concave groove for mounting of the U-shaped seal. U-shaped seal. 3. The U-shaped seal according to claim 2, wherein the outer corners of the corners at both ends of the bottom wall, which can be in close contact with the inner end surface of the concave circumferential groove, are each a right angle. 4. The polyamide resin has a melting point of 300 ° C. or less.
The U-shaped seal according to claim 1, 2 or 3, comprising a nonanediamine-terephthalic acid copolymer at 315 ° C. 5. A rotary sliding seal in which an inner lip portion is in sliding contact with a rotating shaft, wherein a pressing force in which an outer lip portion is in pressure contact with an inner peripheral surface of a concave groove to be mounted has an inner sliding contact with the rotating shaft. Claim 1, which is set to be larger than the crimping force of the lip.
The U-shaped seal according to 2, 3 or 4.