WO2021117600A1

WO2021117600A1 - Seal ring

Info

Publication number: WO2021117600A1
Application number: PCT/JP2020/045064
Authority: WO
Inventors: 筧　幸三; 真也小田
Original assignee: Ntn株式会社
Priority date: 2019-12-11
Filing date: 2020-12-03
Publication date: 2021-06-17

Abstract

Provided is a seal ring with which the generation of galling can be suppressed when incorporated in a housing, and which maintains a low-oil-leakage property. The seal ring 1 is mounted in an annular groove provided on a rotary shaft inserted into a shaft hole of a housing, makes sliding contact with a side wall surface of the annular groove on the non-sealed-fluid side, and contacts an inner circumferential surface of the shaft hole, thereby sealing an annular gap between the rotary shaft and the shaft hole. The seal ring is an injection-molded body of a resin composition, and is provided with a slanted section 6 on at least one end of an outer circumferential surface 3. The slanted section 6 has a slanted surface 7 connected to a ring side surface 4, and a step surface 8 connected in a substantially perpendicular manner to the outer circumferential surface 3, and the width W_a of the step surface 8 in the ring diameter direction is 0.1 mm or less.

Description

Seal ring

The present invention is for sealing a fluid in a device using the fluid pressure of a fluid such as hydraulic fluid, such as an automatic transmission (hereinafter referred to as AT) and a continuously variable transmission (hereinafter referred to as CVT). Regarding the seal ring used.

In devices such as ATs and CVTs, oil seal rings for sealing hydraulic oil are installed at key points. For example, the hydraulic oil supplied from the oil passage between the two annular grooves, which is attached to a pair of separated annular grooves provided on the rotating shaft inserted into the shaft hole of the housing, is applied to the side surface and the inner peripheral surface of both seal rings. The side wall on the opposite side and the outer peripheral surface seal the side wall of the annular groove and the inner peripheral surface of the housing. Each sealing surface of the seal ring holds the hydraulic oil pressure between the two seal rings while sliding contact with the side wall of the annular groove and the inner peripheral surface of the housing.

Conventionally, as such a seal ring, a seal ring made of synthetic resin obtained by injection molding is known (see, for example, Patent Document 1). This seal ring is an annular body having a substantially rectangular cross section, and has a joint at one position in the circumferential direction. The abutment is composed of a pair of complementaryly fitted ends, for example, one abutment has a butt surface on the inner diameter side of the seal ring and a lip protruding from the butt surface on the outer diameter side and retracting. The other abutment has a pocket, the abutment surface, the lip and the abutment surface formed to fit the pocket in a complementary manner, a composite step cut abutment having the pocket and the lip, and the like. It has been adopted.

In recent years, the automobile industry has been accelerating the development of fuel-efficient vehicles against the background of environmental problems. As part of this, the need for low oil leaks is increasing as the demand for idling stop increases. For example, Patent Document 1 describes a resin seal ring having excellent quality that reduces the amount of leakage and maintains stable sealing performance for a long period of time while reducing rotational sliding friction. As a specific configuration, a linear contact portion that linearly abuts on the side wall of the annular groove on the unsealed fluid side is provided on the side surface of the ring continuously from one side to the other side of the abutment port. The line contact portion provided on one side of the mouth and the line contact portion provided on the other side of the mating mouth are provided apart in the radial direction. Further, Patent Document 1 describes a seal ring in which a corner portion between an outer peripheral surface and a side surface of the ring is chamfered to form an inclined surface.

Japanese Unexamined Patent Publication No. 09-001919 International Publication No. 2004/011827

The synthetic resin seal ring obtained by injection molding is expanded in diameter by elastic deformation, mounted in the annular groove of the rotating shaft, and then assembled to the inner diameter of the housing. FIG. 12 shows a state when the rotating shaft 43 equipped with the conventional seal ring 41 is assembled in the housing 44. As shown in FIG. 12, the rotating shaft 43 is inserted from one end side of the housing 44 and assembled. A tapered portion 44a is formed at the open end of the housing 44. However, the outer peripheral surface of the seal ring 41 may be located radially outside the tapered portion 44a of the housing 44 due to eccentricity or the like. In such a case, the ring side surface 42 of the seal ring 41 may come into contact with the end surface 44b of the housing, which may cause a problem such as galling of the seal ring 41.

The present invention (the first invention below) has been made in view of such circumstances, and provides a seal ring capable of suppressing the occurrence of galling and the like at the time of assembling the housing and maintaining a low oil leak property. The purpose.

On the other hand, FIG. 24 shows a process diagram of a seal ring molding die having an inclined surface on the outer peripheral surface. FIG. 24 (a) shows the time when the resin is filled, FIG. 24 (b) shows the time when the mold is opened, and FIG. 24 (c) shows the time when the product is taken out. As shown in FIG. 24A, the molding die has a fixed-side mold 81, a movable-side mold 82, and a core pin 83, and these are abutted to form a cavity 84. The molten resin composition is filled in the cavity 84, and after being held under pressure, it is cooled for a certain period of time to obtain a molded product 85. An inclined surface 85a is formed from the outer peripheral surface of the molded body 85 to the side surface of the ring.

Subsequently, in the mold opening, the movable side mold 82 and the core pin 83 are moved in the X direction with respect to the fixed side mold 81. At this time, normally, the molded body 85 also moves in the X direction in accordance with the movement of the core pins 83 and the like, but the molded body 85 may be attracted to and stick to the fixed side mold 81 (see FIG. 24 (b)). ). When such sticking occurs, the seal ring is easily deformed, for example, the flatness of the side surface of the ring is deteriorated, and oil leakage may increase. In addition, the occurrence of sticking affects the subsequent removal of the product (see FIG. 24C), which may make continuous molding difficult. Such sticking occurs more in the seal ring having an inclined surface than in the seal ring having no inclined surface because the contact area with the fixed side mold 81 increases due to the mold splitting of the mold. It's easy to do.

The present invention (the second invention below) has been made in view of such circumstances, and an object of the present invention is to provide a seal ring capable of suppressing the occurrence of sticking at the time of mold opening and maintaining low oil leak property. And.

The seal ring of the first invention of the present application is mounted on an annular groove provided in a rotating shaft inserted into a shaft hole of a housing, and slidably contacts a side wall surface on the unsealed fluid side of the annular groove. A seal ring that comes into contact with the inner peripheral surface of the shaft hole and seals an annular gap between the rotating shaft and the shaft hole. The seal ring is an injection-molded body of a resin composition. An inclined portion is provided on at least one end side of the outer peripheral surface, and the inclined portion has an inclined surface connected to the ring side surface and a stepped surface connected substantially perpendicular to the outer peripheral surface, and is described in the ring radial direction. The width of the stepped surface is 0.1 mm or less.

The inclined portion is substantially perpendicular to the side surface of the ring and has a connecting surface connecting the inclined surface and the stepped surface. Further, the stepped surface is characterized in that it is located inside in the ring radial direction with respect to the virtual plane on which the inclined surface is extended.

In the axial cross section of the seal ring, the inclination angle of the inclined surface with respect to the outer peripheral surface is 20 to 60 degrees.

The seal ring is characterized by having a compound step cut opening in a part in the circumferential direction.

The base resin of the above resin composition is a polyetherketone (PEK) resin, a polyetheretherketone (PEEK) resin, a polyphenylene sulfide (PPS) resin, or a polyamide-imide (PAI) resin.

The seal ring of the second invention of the present application is mounted on an annular groove provided in a rotating shaft inserted into a shaft hole of a housing, and slidably contacts a side wall surface on the unsealed fluid side of the annular groove. A seal ring that comes into contact with the inner peripheral surface of the shaft hole and seals an annular gap between the rotating shaft and the shaft hole. The seal ring is an injection molded body of a resin composition. A joint is provided in a part in the circumferential direction, and a recess is provided on the inner peripheral surface in the radial direction of the ring, and the depth of the recess is 1% to 10% of the radial length of the seal ring. It is a feature.

The seal ring is characterized by having an inclined portion on at least one end side of the outer peripheral surface, and the inclined portion has an inclined surface connected to the side surface of the ring.

The inclined portion has a stepped surface connected substantially perpendicular to the outer peripheral surface, and the width of the stepped surface in the ring radial direction is 0.1 mm or less.

The width of the recess in the ring axis direction is 2% to 60% of the axial length of the seal ring.

The recess is a concave groove continuously provided along the ring circumferential direction, and the formation range of the concave groove in the ring circumferential direction is 15% or more with respect to the inner circumference of the seal ring. And.

The seal ring of the first invention of the present application is an injection-molded body of a resin composition, and has an inclined portion on at least one end side of the outer peripheral surface, and the inclined portion has an inclined portion connected to a ring side surface and an outer peripheral surface. Since it has a stepped surface connected substantially vertically and the width of the stepped surface in the ring radial direction is 0.1 mm or less, when the seal ring is inserted into the housing and assembled, the stepped surface at the outer diameter side end is formed. , It is possible to suppress the contact with the end face of the housing and prevent the occurrence of galling. As a result, scratches such as dents are prevented on the sealing surface on the side surface of the ring, so that the low oil leak property of the sealing ring can be maintained.

The inclined portion is substantially perpendicular to the side surface of the ring and has a connecting surface connecting the inclined surface and the stepped surface. Therefore, when the inclined portion of the seal ring is applied to the tapered portion of the housing and inserted, the stepped surface is formed on the housing. It is possible to further suppress the contact with the end face. Further, since the stepped surface is located inside in the ring radial direction with respect to the virtual plane on which the inclined surface is extended, the boundary between the stepped surface and the outer peripheral surface does not protrude from the virtual plane, and even if the end surface of the housing hits, it is gnawing. Can be prevented.

In the axial cross section of the seal ring, the inclination angle of the inclined surface with respect to the outer peripheral surface is 20 to 60 degrees, so even if the eccentricity of the seal ring is large with respect to the rotating shaft or the end surface of the housing hits. The occurrence of galling can be suppressed.

The seal ring has a compound step-cut joint in a part of the circumferential direction, so the oil sealability is particularly excellent. Further, since the base resin of the resin composition is PEK resin, PEEK resin, PPS resin, or PAI resin, it has excellent flexural modulus, heat resistance, etc., and does not crack even if the diameter is increased when it is incorporated into the groove. , Can be used even when the temperature of the hydraulic oil to be sealed becomes high.

The seal ring of the second invention of the present application is an injection molded product of a resin composition, and has a recess in a part in the circumferential direction and a recess in the inner peripheral surface in the ring radial direction. Since the depth is 1% to 10% of the radial length of the seal ring, the followability of the molded product to the core pin or the like is improved when the mold is opened, and sticking to the fixed-side mold can be suppressed. Further, by setting the depth of the recess within a predetermined range, it is possible to ensure the ease of removal from the mold while preventing the seal ring from falling into the annular groove. As a result, deformation caused by sticking at the time of mold opening can be suppressed, and thus low oil leak property can be maintained.

When assembling the seal ring to the housing, the side surface of the ring comes into contact with the end surface of the housing, which may cause problems such as galling of the seal ring, which may affect the seal property. In this respect, since the seal ring is provided with an inclined portion on at least one end side of the outer peripheral surface and the inclined portion has an inclined surface connected to the side surface of the ring, the corner portion is chamfered and the occurrence of galling can be suppressed. On the other hand, with the formation of the inclined surface, there is more concern about sticking to the fixed-side mold when the mold is opened, but since the inner peripheral surface has the recess, sticking can be suppressed.

The inclined portion has a stepped surface connected substantially perpendicular to the outer peripheral surface, and the width of the stepped surface in the ring radial direction is 0.1 mm or less. It is possible to prevent the stepped surface from hitting the end surface of the housing and prevent the occurrence of galling. As a result, scratches such as dents are prevented on the sealing surface on the side surface of the ring, which is more effective in maintaining the low oil leakage property of the sealing ring. Further, by providing the stepped surface, the mold split surface can be set on the extension line thereof, and the variation in the outer diameter dimension of the seal ring can be suppressed.

Since the width of the concave portion in the ring axial direction is 2% to 60% of the axial length of the seal ring, it is possible to suitably prevent the seal ring from falling while exerting the anchor effect.

The recess is a concave groove continuously provided along the ring circumferential direction, and the forming range of the concave groove in the ring circumferential direction is 15% or more with respect to the inner circumference of the seal ring. The anchor effect can be exerted almost as a whole.

It is a top view which shows an example of the seal ring of 1st invention of this application. FIG. 1 is a cross-sectional view and a partially enlarged view of the seal ring of FIG. It is a figure for demonstrating the positional relationship between an inclined surface and a stepped surface. It is sectional drawing and the partially enlarged view of another example of the seal ring of 1st invention of this application. It is a figure which shows the state at the time of assembling the seal ring of FIG. 1 to a housing. It is sectional drawing which shows the state which incorporated the seal ring of FIG. 1 into an annular groove. It is sectional drawing of the molding die at the time of injection molding. It is sectional drawing which shows the mold release process. It is sectional drawing of the seal ring of Examples A1 to A4. It is sectional drawing of the seal ring of Comparative Examples A1 and A2. It is the schematic of the measurement test of the oil leak amount of a seal ring. It is a figure which shows the state at the time of assembling the conventional seal ring to a housing. It is a top view which shows an example of the seal ring of the 2nd invention of this application. It is sectional drawing of the seal ring of FIG. It is a process diagram of the molding die of the seal ring of FIG. It is sectional drawing which shows the state which incorporated the seal ring of FIG. 13 into an annular groove. 2 is a cross-sectional view and a view taken along the line A of another example of the seal ring of the second invention of the present application. It is sectional drawing of another example of the seal ring of the 2nd invention of this application. It is sectional drawing and the partially enlarged view of another example of the seal ring of 2nd invention of this application. It is sectional drawing of the seal ring of Examples B1 to B3 and the like. It is sectional drawing of the seal ring of Comparative Examples B1 and B2. It is a figure for demonstrating the taking-out process of the comparative example B2. It is the schematic of the measurement test of the oil leak amount of a seal ring. It is a process drawing of the molding die of the conventional seal ring.

An example of the seal ring of the first invention of the present application will be described with reference to FIGS. 1 and 2. 1 is a plan view of the seal ring, FIG. 2A is a sectional view taken along line AA, and FIG. 2B is a partially enlarged view thereof. As shown in FIG. 1, the seal ring 1 is an annular body having a substantially rectangular cross section formed by injection molding using a mold. The seal ring 1 is a cut type ring having an opening 10 at one position in the circumferential direction, and is mounted in an annular groove by expanding its diameter by elastic deformation. The abutment 10 is composed of a pair of ends. The shape of the pair of ends can be straight cut, angle cut, or the like, but it is preferable to adopt the composite step cut shown in FIG. 1 because of its excellent oil sealability.

The size of the seal ring (outer diameter φ, inner diameter φ, ring width (axial length), ring thickness (diameter length), etc.) is appropriately set depending on the application. For example, the inner diameter φ of the seal ring is 9 mm to 75 mm, and the outer diameter φ is 13 mm to 80 mm.

In the seal ring 1, the ring side surface 4 serves as a sliding surface with the side wall surface of the annular groove. As shown in FIG. 2A, a step portion 5 which is a protruding portion from the mold at the time of injection molding is provided at a corner portion between the ring inner peripheral surface 2 and the ring side surface 4. In FIG. 2A, the step portions 5 are provided on both sides. Further, an inclined portion 6 is provided at a corner portion between the ring outer peripheral surface 3 and the ring side surface 4. The inclined portion 6 is a non-contact portion with the side wall surface of the annular groove over the entire circumference of the ring. A plurality of lubricating grooves formed of recesses may be formed at the inner diameter side end of the ring side surface 4 so as to be separated from each other in the circumferential direction.

The inclined portion 6 will be further described. As shown in FIG. 2B, the inclined portion 6 has an inclined surface 7 connected to the ring side surface 4, a stepped surface 8 connected perpendicularly to the ring outer peripheral surface 3, and a connecting surface 9. .. In the first invention of the present application, the stepped surface 8 is a surface (also referred to as a mold split surface) formed by mold splitting of a mold. When the sealing ring 1 is provided with the inclined portion 6, if the mold split surface is brought on the extension line of the ring side surface 4, the inclined portion 6 becomes undercut when the mold is released from the mold, and the molded body is formed. Difficult to remove from the mold. Therefore, in the first invention of the present application, the mold split surface of the mold is arranged on the extension line of the stepped surface 8 of the seal ring. On top of that, and with 0.1mm or less width _{W a} of the stepped surface 8 of the ring radially. By reducing the mold split step in this way, problems such as galling of the seal ring are prevented. In particular, the width _{W a} is preferably 0.01mm ~ 0.05mm.

The seal ring 1 shown in FIG. 2 is provided with inclined portions on both sides of the outer peripheral surface 3 of the ring. Of the inclined portions on both sides, one inclined portion (inclined portion 6) has a stepped surface 8, and the other inclined portion is composed of only an inclined surface. The stepped surface 8 may be formed on at least one inclined portion, but may be formed symmetrically on both inclined portions. In this case, the inclined portions on both sides have a stepped surface, and the dependence on the assembling direction is eliminated.

The depth of the inclined surface 7 from the sliding surface becomes deeper toward the outside in the ring radial direction and is constant in the ring axis direction. In the axial cross section of the seal ring 1, the inclination angle α (see FIG. 2A) of the inclined surface 7 with respect to the outer peripheral surface 3 of the ring is, for example, 20 degrees to 60 degrees. The inclination angle α is preferably 30 degrees to 50 degrees, more preferably 30 degrees to 45 degrees, and further preferably 40 degrees to 45 degrees. If the inclination angle α is less than 20 degrees, it is easy to hit the end face of the housing when the eccentricity of the seal ring (protrusion from the annular groove) is large, and galling may occur. Further, if the inclination angle α exceeds 60 degrees, the seal ring does not smoothly line up when it hits the end surface of the housing, and it may be caught on the stepped surface 8 and minute galling may occur.

Further, in the seal ring 1 of FIG. 2, a connecting surface 9 perpendicular to the ring side surface 4 is provided between the inclined surface 7 and the stepped surface 8. By providing the connecting surface 9, the stepped surface 8 can be easily accommodated in the inclined portion. The connecting surface 9 may be a surface substantially perpendicular to the ring side surface 4, and may be formed of a flat surface or a curved surface. _{The width W b} of the connecting surface 9 in the ring axis direction is not particularly limited, but is preferably larger than _{the width W a} of the stepped surface 8. As a specific dimension, the width W _b of the connecting surface 9 is preferably, for example, 0.05 mm to 0.3 mm. More preferably, it is 0.05 mm to 0.1 mm.

FIG. 3A describes the positional relationship between the inclined surface and the stepped surface. As shown in FIG. 3A, assuming that the virtual plane extending the inclined surface 7 is F, the stepped surface 8 is located inside the virtual plane F in the ring radial direction. In other words, the corner portion P, which is the boundary between the outer peripheral surface 3 and the stepped surface 8, does not protrude outward in the radial direction from the virtual plane F. By setting the stepped surface 8 inside the inclined portion in this way, it is possible to prevent the stepped surface 8 (including the corner portion P) from hitting the end surface of the housing even when the inclined surface 7 is applied to the tapered portion of the housing and pushed in. It can prevent galling.

FIG. 3B shows an example of deformation of the stepped surface of the inclined portion. As shown in FIG. 3B, the stepped surface 8'is formed by a curved surface substantially perpendicular to the outer peripheral surface 3, and the boundary portion between the outer peripheral surface 3 and the stepped surface 8 is formed in an R shape. The stepped surface 8'is obtained, for example, by polishing the corner portion P shown in FIG. 3A by barrel polishing or the like. By forming the boundary portion into an R shape, galling of the stepped surface 8'can be further prevented. Also in the modified example of FIG. 3B, the stepped surface 8'is located inside the virtual plane F in the ring radial direction.

Another example of the seal ring of the first invention of the present application is shown in FIG. FIG. 4A is a cross-sectional view of the seal ring, and FIG. 4B is a partially enlarged view thereof. The seal ring 11 has a different structure of the inclined portion than the seal ring 1 of FIG. Specifically, as shown in FIG. 4B, the inclined portion 16 has an inclined surface 17 connected to the ring side surface 14 and a stepped surface 18 connected perpendicularly to the ring outer peripheral surface 13. .. Also in this embodiment, the width _{W a} of the stepped surface 18 of the ring radial direction is at 0.1mm or less, preferably 0.01 mm ~ 0.05 mm. The preferable range of the inclination angle β of the inclined surface 17 (see FIG. 4A) is the same as the range of the inclined angle α of the inclined surface 7 described above.

FIG. 5 shows the state when the housing is assembled. In FIG. 5, the seal ring 1 and the housing 22 show a cross section. The seal ring 1 is first expanded in diameter using a jig (not shown) and mounted in the annular groove 21a of the rotating shaft 21. With the seal ring 1 attached, the rotating shaft 21 is inserted into the housing 22 and assembled. As shown in FIG. 5, the open end of the housing is provided with a tapered portion 22a formed of an inclined surface (for example, an inclined angle of 30 to 50 degrees). However, if the wall thickness of the housing is small, or if a sufficient taper cannot be formed so as not to interfere with the seal ring, the outer peripheral surface of the seal ring is located outside the taper of the housing due to eccentricity. Sometimes. In such a case, galling may occur when the ring side surface of the seal ring hits the end surface of the housing (see FIG. 12).

On the other hand, in the seal ring according to the first invention of the present application, as shown in FIG. 5B, an inclined portion having the above-mentioned inclined surface 7 and stepped surface 8 is formed on one end side of the outer peripheral surface 3 of the ring. Therefore, even when the amount of eccentricity of the seal ring becomes large, the inclined angle portion 6a, which is the boundary portion between the ring side surface 4 and the inclined surface 7, can be easily accommodated in the tapered portion 22a of the housing 22. Become. That is, the inclined angle portion 6a can be easily positioned inside the tapered portion diameter R. Further, since the width of the stepped surface 8 is set to be small, it is possible to prevent the end surface 22b of the housing 22 from hitting the stepped surface 8 and prevent the occurrence of galling.

In order to accommodate the inclined portion 6a of the seal ring 1 in the tapered portion 22a of the housing 22, the inclined portion dimension W _c of the seal ring 1 is set. The inclined portion dimension W _c is the distance from the ring outer peripheral surface 3 to the inclined angle portion 6a in the ring radial direction, and is the free outer diameter φ of the seal ring 1, the ring thickness T, the depth h of the annular groove, and the housing. It is set by the taper diameter R and the maximum amount of eccentricity due to the drop during assembly. The ring thickness T is the distance from the outer peripheral surface 3 of the ring to the inner peripheral surface 2 of the ring, and the depth h of the annular groove is the radial length from the outer peripheral end surface of the rotating shaft 21 to the bottom of the annular groove 21a. The tapered portion diameter R of the housing is the outer peripheral diameter of the tapered portion 22a of the housing 22. Here, the maximum eccentricity amount is the maximum value of the distance at which the opposite portion protrudes from the annular groove when the seal ring falls into the annular groove. The maximum eccentricity is the maximum value of the outer diameter φ, the minimum value of the ring thickness T, and the minimum value of the annular groove depth h when each dimension (outer diameter φ, T, h, R) changes. It is set using the minimum value of the value and the taper diameter R. By setting in this way, the inclined angle portion 6a of the seal ring 1 can be positioned in the tapered portion 22a of the housing 22 even when the seal ring 1 is maximally eccentric, and the seal ring can be smoothly inserted. it can.

The outline of the usage pattern of the seal ring will be described with reference to FIG. The seal ring 1 is mounted in an annular groove 21a provided in the rotating shaft 21 inserted into the shaft hole 22c of the housing. The arrow in the figure is the direction in which the pressure from the hydraulic oil is applied, and the right side in the figure is the unsealed fluid side. The seal ring 1 is slidably in contact with the side wall surface 21b on the unsealed fluid side of the annular groove 21a on the ring side surface 4. Further, the outer peripheral surface 3 is in contact with the inner peripheral surface of the shaft hole 22c. This sealing structure seals an annular gap between the rotating shaft 21 and the shaft hole 22c. Further, the type of hydraulic oil is appropriately used according to the intended use. For example, it is used under the conditions that the oil temperature is about −30 to 150 ° C., the oil pressure is about 0 to 3.0 MPa, and the rotation speed of the rotating shaft is about 0 to 7000 rpm.

The seal ring of the first invention of the present application is an injection molded product of a resin composition. As the base resin of the resin composition, any synthetic resin that can be injection-molded can be used. For example, thermoplastic polyimide resin, PEK resin, PEEK resin, PPS resin, PAI resin, polyamide (PA) resin, polybutylene terephthalate (PBT) resin, polyethylene terephthalate (PET) resin, polyethylene (PE) resin, polyacetal (POM). Examples thereof include resins and phenol (PF) resins. These resins may be used alone or as a polymer alloy in which two or more kinds are mixed. Among these resins, PEK resin, PEEK resin, PPS resin, or PAI resin is preferably used as the base resin because it is excellent in frictional wear characteristics, flexural modulus, heat resistance, slidability, and the like. These resins have a high elastic modulus, are hard to crack even if the diameter is increased when they are incorporated into the annular groove, can be used even when the oil temperature of the hydraulic oil to be sealed becomes high, and there is no concern about solvent cracks.

In addition, if necessary, the above-mentioned base resin can be used as a fibrous reinforcing material such as carbon fiber, glass fiber, or aramid fiber, a spherical filler such as spherical silica or spherical carbon, a scale-like reinforcing material such as mica or talc, or potassium titanate whisker. Fine fiber reinforcing materials such as can be blended. Further, a polytetrafluoroethylene (PTFE) resin, a solid lubricant such as graphite and molybdenum disulfide, a sliding reinforcing material such as calcium phosphate and calcium sulfate, and a pigment such as carbon black can also be blended. These can be blended alone or in combination.

The above raw materials are melt-kneaded into pellets for molding, which are then molded into a predetermined shape by an injection molding method. FIG. 7 shows a cross-sectional view of the molding die. As shown in FIG. 7, the molding die has a fixed side mold 23, a movable side mold 24, and a core pin 25. In the molding die, the cavity 26 is formed by the fixed side mold 23 and the movable side mold 24, which are abutted by the abutting surface PL, and the core pin 25. The molten resin composition is filled in the cavity 26, and after being held under pressure, it is cooled for a certain period of time to obtain a molded product 27. The inclined portion of the molded body 27 including the stepped surface 27a is formed by the fixed-side mold 23. In the abutting surface PL, the end portion of the fixed side mold 23 (PL surface on the outer peripheral direction side of the seal ring) is directed toward the cavity 26 rather than the end portion of the movable side mold 24 (PL surface on the outer peripheral direction side of the seal ring). Due to the difference in the position of the end portion, a mold split step (step surface 27a) is generated.

Subsequently, the fixed side mold and the movable side mold are opened and the molded body is taken out. In FIG. 8, the mold removal process is shown step by step. In FIG. 8A, the fixed-side mold 23 and the movable-side mold 24 are molded at the abutting surface. After the mold is opened, the core pin 25 advances toward the fixed-side mold 23, so that the molded body 27 is separated from the movable-side mold 24 (FIG. 8 (b)). The step portion 25a of the core pin 25 forms a step portion of the inner diameter side end portion of the seal ring. As shown in FIG. 8 (c), the molded body 27 is taken out from the molding die by further advancing the core pin 25. The abutment of the taken-out molded body 27 has a pair of ends separated from each other, but is closed by heat fixing or the like to obtain a seal ring 1 as shown in FIG.

An example of the seal ring of the second invention of the present application will be described with reference to FIGS. 13 to 14. FIG. 13 is a plan view of the seal ring, and FIG. 14 is a sectional view taken along line BB. As shown in FIG. 13, the seal ring 51 is an annular body formed by injection molding using a mold and having a substantially rectangular cross section. The seal ring 51 is a cut type ring having an opening 60 at one position in the circumferential direction, and is mounted in an annular groove by expanding its diameter by elastic deformation. The abutment 60 is composed of a pair of ends. The shape of the pair of ends can be straight cut, angle cut, or the like, but it is preferable to adopt the composite step cut shown in FIG. 13 because of its excellent oil sealability.

The size of the seal ring (outer diameter φ, inner diameter φ, ring width W (axial length), ring thickness T (diameter length), etc.) is appropriately set depending on the application and the like. For example, the inner diameter φ of the seal ring is 9 mm to 75 mm, and the outer diameter φ is 13 mm to 80 mm.

In the seal ring 51, the ring side surface 54 or 54'is a sliding surface with the side wall surface of the annular groove. As shown in FIG. 14, at the corners of the inner peripheral surface 52 of the ring and the side surfaces 54, 54'of the ring, stepped portions 55, 55', which are protruding portions from the mold during injection molding, are provided. In FIG. 14, the step portions 55 and 55'are provided at both ends in the ring axial direction and are recessed in the ring radial direction. Further, inclined portions 56, 56'composed of inclined surfaces are provided at the corners on both sides of the ring outer peripheral surface 53 and the ring side surfaces 54, 54'. The inclined portions 56 and 56'are provided over the entire circumference of the ring and serve as non-contact portions with the side wall surface of the annular groove. It should be noted that a plurality of lubricating grooves formed of recesses may be formed at the inner diameter side ends of the ring side surfaces 54 and 54'distance in the circumferential direction.

The depth of the inclined surface at the inclined portions 56, 56'from the sliding surface (ring side surface 54 or 54') becomes deeper toward the outside in the ring radial direction and is constant in the ring axial direction. In the axial cross section of the seal ring 51, the inclination angle γ of the inclined surface with respect to the outer peripheral surface 53 of the ring is, for example, 20 degrees to 60 degrees. The inclination angle γ is preferably 30 degrees to 50 degrees, more preferably 30 degrees to 45 degrees, and further preferably 40 degrees to 45 degrees. If the inclination angle γ is less than 20 degrees, when the seal ring is assembled to the housing, if the eccentricity of the seal ring (protruding from the annular groove) is large, it is likely to hit the end face of the housing, and galling may occur. Further, if the inclination angle γ exceeds 60 degrees, the seal ring may not be smoothly guided when it hits the end face of the housing.

As shown in FIG. 14, the seal ring 51 has a recess 57 recessed in the ring radial direction on the inner peripheral surface 52 of the ring between the pair of step portions 55 and 55'. The recess 57 is an undercut portion when the molding die is opened, as shown in FIG. 15 described later. The undercut portion is a portion that is engaged with the mold (for example, a core pin), that is, a portion that is hooked on the mold. In FIG. 14, the recess 57 is an arc groove having an arcuate cross section formed continuously along the circumferential direction of the ring. This arc groove is not open to the step portions 55 and 55'on both sides, but is a concave groove closed in the inner peripheral surface of the ring. The shape of the concave groove is not particularly limited, and may be, for example, a square groove having a rectangular cross section or a triangular groove having a triangular cross section.

_{The depth W d} of the recess 57 of the seal ring 51 is 1% to 10% of the ring thickness T. The ring thickness T refers to the maximum thickness in the ring radial direction of the seal ring 1, and is the length between the inner peripheral surface of the ring 52 and the outer peripheral surface of the ring 53 in FIG. The depth W _d of the recess 57 refers to the length of a perpendicular line drawn from the most recessed point of the recess to the virtual surface f of the inner peripheral surface of the ring assuming that the recess is not formed. If the depth W _d is less than 1% of the ring thickness T, it is difficult to obtain the anchor effect when the mold is opened, and sticking may occur. Further, if the depth W _d exceeds 10% of the ring thickness T, the ring becomes more likely to be caught by the mold, and it may be difficult to finally remove the ring from the mold. The depth W _d is preferably 3% to 5% of the ring thickness T.

From another viewpoint, _{it is preferable that the depth W d} of the recess 57 is shallower than the depth (diameter length) of the step portions 55 and 55'. Further, specific values of the depth _{W d} of the recess 57 is about 0.05 mm ~ 0.2 mm. The stepped portions 55 and 55'are protruding from the mold, and the depth (diameter length) of the stepped portion exceeds 10% of the ring thickness T in order to prevent deformation of the seal ring at the time of protrusion. It is provided.

Width W _e in the ring axial direction of the recess 57 is not particularly limited. However, if the width W _e is small, there is a possibility that sticking difficult to obtain anchor effect at the time of mold opening occurs, if the short shot occurs in the case of using the width W _e is large, for example, a high melt viscosity material There is. Therefore, the width _{W e} of the concave portion 57 is preferably from 2% to 60% of the ring width W, and more preferably 5% to 40%. The ring width W refers to the maximum width in the ring axis direction of the seal ring 1, and in FIG. 14, it is the length between one ring side surface 54 and the other ring side surface 54'. Width W _e is a ring axial width of a portion open to the ring inner peripheral surface 52. Further, it is desirable that the product of the ratio (%) _{of the depth W d to} the ring thickness T and the ratio (%) of the width W _{e to} the ring width W of the recess 57 is in the range of 10 or more and 500 or less. If it is less than 10, the anchor effect is difficult to obtain at the time of mold opening and sticking may occur, and if it exceeds 500, a short shot may occur when a material having a high melt viscosity is used.

The formation range of the recess 57 in the ring circumferential direction is preferably 15% or more, more preferably 50% or more with respect to the inner circumference of the seal ring 51. Anchor effect can be easily obtained by setting the forming range of the recess 57 to 15% or more. On the other hand, it is preferable not to form a recess in the periphery of the abutment 60 (see FIG. 13), for example, a portion within a range of ± 10 ° in the ring circumferential direction about the abutment 60. The upper limit of the forming range of the recess 57 in the ring circumferential direction is, for example, 90%, preferably 80%.

In FIG. 14, a concave groove continuously formed along the circumferential direction is shown as the concave portion, but even if the concave portion is composed of a plurality of (for example, two) concave grooves divided in the circumferential direction of the ring. Good. In this case, the formation range (total of each concave groove) in the ring circumferential direction of the plurality of concave grooves is preferably 15% or more, more preferably 50% or more with respect to the inner circumference of the seal ring 51. The upper limit is, for example, 90%, preferably 80%.

Further, the concave portion of the seal ring of the second invention of the present application is not limited to the concave groove, and may be composed of holes. In this case, for example, a plurality of holes can be arranged so as to be separated from each other in the circumferential direction of the ring. Each of the above numerical ranges can be adopted for the hole depth, the width in the ring axis direction, and the formation range in the ring circumferential direction (in the case of a plurality of holes, the total).

The seal ring of the second invention of the present application is an injection molded product of a resin composition. As the base resin of the resin composition, any synthetic resin that can be injection-molded can be used. For example, thermoplastic polyimide resin, PEK resin, PEEK resin, PPS resin, PAI resin, PA resin, PBT resin, PET resin, PE resin, POM resin, PF resin and the like can be mentioned. These resins may be used alone or as a polymer alloy in which two or more kinds are mixed. Among these resins, PEK resin, PEEK resin, PPS resin, or PAI resin is preferably used as the base resin because it is excellent in frictional wear characteristics, flexural modulus, heat resistance, slidability, and the like. These resins have a high elastic modulus, are hard to crack even if the diameter is increased when they are incorporated into the annular groove, can be used even when the oil temperature of the hydraulic oil to be sealed becomes high, and there is no concern about solvent cracks.

In addition, if necessary, the above-mentioned base resin can be used as a fibrous reinforcing material such as carbon fiber, glass fiber, or aramid fiber, a spherical filler such as spherical silica or spherical carbon, a scale-like reinforcing material such as mica or talc, or potassium titanate whisker. Fine fiber reinforcing materials such as can be blended. Further, a solid lubricant such as PTFE resin, graphite and molybdenum disulfide, a sliding reinforcing material such as calcium phosphate and calcium sulfate, and a pigment such as carbon black can also be blended. These can be blended alone or in combination.

The above raw materials are melt-kneaded into pellets for molding, which are then molded into a predetermined shape by an injection molding method. FIG. 15 shows a process diagram of the molding die. As shown in FIG. 15A, the molding die has a fixed-side mold 61, a movable-side mold 62, and a core pin 63, and these are abutted to form a cavity 64. The molten resin composition is filled in the cavity 64, and after being held under pressure, it is cooled for a certain period of time to obtain a molded product 65. A concave portion 65a is provided on the inner peripheral surface of the molded body 65, and a convex portion 63a is formed on the core pin 63 corresponding to the concave portion of the concave portion 65a.

Subsequently, in the mold opening shown in FIG. 15B, the movable side mold 62 and the core pin 63 are moved in the X direction with respect to the fixed side mold 61. At this time, since the concave portion 65a is caught by the convex portion 63a of the core pin 63, the molded body 65 also moves in the X direction following the movement of the core pin 63. In this way, the recess 65a serves as an undercut portion, and the molded body 65 is physically fixed, so that sticking to the fixed-side mold 61 is suppressed.

After that, as shown in FIG. 15 (c), the molded body 65 is separated from the movable mold 62 by advancing the core pin 63 toward the fixed mold 61 in the Y direction. Then, as shown in FIG. 15 (d), the engaging portion 66a of the take-out hand 66 is engaged with a part of the ring side surface 65b of the molded body 65 and moved in the Z direction, whereby the molded body 65 becomes a core pin. Taken out of 63. The abutment of the taken-out molded body 65 has a pair of ends separated from each other, but is closed by heat fixing or the like to obtain the seal ring 51 shown in FIG.

The outline of the usage pattern of the seal ring will be described with reference to FIG. The seal ring 51 is mounted in an annular groove 71a provided in the rotating shaft 71 inserted into the shaft hole 72a of the housing 72. The arrow in the figure is the direction in which the pressure from the hydraulic oil is applied, and the right side in the figure is the unsealed fluid side. The seal ring 51 is slidably in contact with the side wall surface 71b on the unsealed fluid side of the annular groove 71a on the ring side surface 54 thereof. Further, the outer peripheral surface 53 of the ring is in contact with the inner peripheral surface of the shaft hole 72a. This sealing structure seals an annular gap between the rotating shaft 71 and the shaft hole 72a. Further, the type of hydraulic oil is appropriately used according to the intended use. For example, it is used under the conditions that the oil temperature is about −30 to 150 ° C., the oil pressure is about 0 to 3.0 MPa, and the rotation speed of the rotating shaft is about 0 to 7000 rpm.

As shown in FIG. 16, in the seal ring 51, the outer peripheral surface 53 of the ring and the side surface 54 of the ring related to the oil leak are not formed with a recess to be an undercut portion, and the recess 57 is formed on the inner peripheral surface 52 of the ring. Therefore, low oil leak property can be maintained. Further, since the recess 57 suppresses sticking to the fixed-side mold when the mold is opened, deformation due to sticking, for example, deterioration of flatness of the ring side surface 54 can be suppressed, and as a result, low oil leak property is maintained. It leads to.

Hereinafter, another example of the seal ring of the second invention of the present application will be described with reference to FIGS. 17 to 19.

The seal ring 51 shown in FIG. 17 has a different recessed structure from the seal ring 51 shown in FIG. FIG. 17A is a cross-sectional view of the seal ring, and FIG. 17B is a view taken along the arrow C. The description of the configuration other than the concave portion will be omitted.

As shown in FIG. 17A, the recess 57A is a recess formed on the inner peripheral surface 52 of the ring from one step 55 to the other step 55'. The depth W _d of the recess 57A is constant and is represented as the length of a perpendicular line drawn from the bottom surface of the recess to the virtual surface f. Depth _{W d} of the concave portion 57A in this configuration satisfies the 1% to 10% of the ring thickness T.

As shown in FIG. 17B, in the view of the seal ring 51 viewed from the inner peripheral surface side of the ring, the recess 57A has a trapezoidal shape, and its circumferential width becomes smaller toward one side in the ring axial direction. There is. Specifically, a circumferential width L _a opening into one of the step portion 55 is smaller than the circumferential width L _b which is open to the other stepped portion 55 '. In the case of this configuration, when the molding die is opened, the movable die and the core pin are moved toward the side where the circumferential width of the recess 57A is smaller, that is, in the X direction. As a result, the wide portion of the convex portion of the core pin is caught in the concave portion 57A, so that the sticking to the fixed side mold can be suppressed. Incidentally, while exhibiting the anchor effect at the time of mold opening, to ensure the extraction of the mold by taking out the hand (see FIG. 15 (d)), the circumferential width L _b, to the circumferential width L _a It is preferably 1.05 times to 1.2 times.

In FIG. 17, the recesses 57A may be formed at a plurality of locations on the inner peripheral surface 52 of the ring. For example, 3 to 5 locations are formed at equal intervals in the circumferential direction of the ring. By forming it at a plurality of places, the anchor effect can be exerted on almost the entire ring.

The seal ring 51 shown in FIG. 18 has a different recessed structure from that of the seal ring 51 shown in FIG. The description of the configuration other than the concave portion will be omitted. As shown in FIG. 18, the recess 57B is a recess that is inclined from the step 55 to the step 55'on the inner peripheral surface of the ring. The depth of the recess 57B from the virtual surface f becomes deeper as it approaches the step portion 55'. In this case, the depth W _d of the recess 57B is expressed as the length of a perpendicular line drawn from the most recessed point of the recess 57B to the virtual surface f. Depth _{W d} of the concave portion 57B in this configuration satisfies the 1% to 10% of the ring thickness T.

In the case of this configuration, when opening the molding die, the movable die and the core pin are moved toward the side where the depth of the recess 57B is shallow, that is, in the X direction. As a result, the highly formed portion of the convex portion of the core pin is caught in the concave portion 57B, so that the sticking to the fixed side mold can be suppressed. The recess 57B is continuously provided along the circumferential direction of the ring, and the forming range thereof is preferably 15% or more, more preferably 50% or more with respect to the inner circumference of the seal ring 51.

The seal ring 51 shown in FIG. 19 is different from the seal ring 51 of FIG. 14 in the configuration of the inclined portion provided on the outer peripheral surface. FIG. 19A is a cross-sectional view of the seal ring, and FIG. 19B is a partially enlarged view thereof. The description of the configuration other than the inclined portion will be omitted.

As shown in FIG. 19, the inclined portion 56 is perpendicular to the inclined surface 56a connected to the ring side surface 54 and the ring outer peripheral surface 53, similarly to the seal ring 1 (see FIG. 2) of the first invention of the present application. It has a stepped surface 58 connected to the surface and a connecting surface 59. The stepped surface 58 is a surface formed by the mold splitting of the mold (also referred to as a mold splitting surface), and in this configuration, the mold split surface of the fixed side mold and the movable side mold is the stepped surface 58 of the seal ring 51. It is placed on the extension line of. By providing the stepped surface 58, variation in the outer diameter dimension of the seal ring can be suppressed. On the other hand, if the mold split step is large, there is a risk of galling of the seal ring when assembling the housing. Therefore, the width W _f of the step surface 58 in the ring radial direction (see FIG. 19 (b)) is 0.1 mm. The following is preferable, and 0.01 mm to 0.05 mm is more preferable.

The seal ring 51 shown in FIG. 19 is provided with inclined portions on both sides of the ring outer peripheral surface 53. Of the inclined portions on both sides, one inclined portion has a stepped surface 58, and the other inclined portion is composed of only an inclined surface. The stepped surface 58 is preferably formed on at least one inclined portion, and may be formed symmetrically on both inclined portions. In this case, the inclined portions on both sides have a stepped surface, and the dependence on the assembling direction is eliminated.

Further, in the seal ring 51 of FIG. 19, a connecting surface 59 perpendicular to the ring side surface 54 is provided between the inclined surface 56a and the stepped surface 58. By providing the connecting surface 59, the stepped surface 58 can be easily accommodated in the inclined portion. The connecting surface 59 may be a surface substantially perpendicular to the ring side surface 54, and may be formed of a flat surface or a curved surface. _{The width W g} of the connecting surface 59 in the ring axis direction (see FIG. 19B) is not particularly limited, but is preferably larger than _{the width W f of the stepped surface 58.} As specific dimensions, the width _{W g} of the connection surface 59 is preferably, for example, 0.05 mm ~ 0.3 mm. More preferably, it is 0.05 mm to 0.1 mm.

Regarding the positional relationship between the inclined surface and the stepped surface, as shown in FIG. 3 above, galling is prevented by locating the stepped surface inside the virtual plane on which the inclined surface is extended in the ring radial direction. It will be easier to do.

In FIGS. 13 to 19, the seal ring having an inclined portion on the outer peripheral surface of the ring is shown, but the seal ring of the second invention of the present application is not limited to this, and the seal ring having no inclined portion, that is, the corner portion. It can also be applied to seal rings that are not chamfered. Further, in FIGS. 13 to 19, a seal ring having a pair of stepped portions recessed in the ring radial direction at both ends in the ring axis direction is shown, but the seal ring of the second invention of the present application is not limited to this. It can also be applied to a seal ring that does not have the above-mentioned step portion.

Example A1 to Example A4
Using a resin composition containing PEEK resin as a base resin and carbon fiber and PTFE resin, seal rings having the respective shapes shown in FIG. 9 were produced by injection molding. The dimensions of the seal rings of Examples A1 to A4 are an outer diameter of φ32 mm, an inner diameter of φ28 mm, a ring width (axial length) of 2.3 mm, and a ring thickness (radial length) of 2 mm. The seal ring of each example are inclined portion forming with a connecting surface 9 and the inclined surface 7 and the stepped surface 8, the width W _a of the stepped surface _(see FIG. 2) is 0.05 mm, connection surface The width W _b (see FIG. 2) is 0.08 mm. The inclination angles θ of the inclined surfaces are different, and Example A1 is 40 degrees, Example A2 is 30 degrees, Example A3 is 60 degrees, and Example A4 is 20 degrees. The inclined portion dimension W _c (see FIG. 5) of each seal ring is 0.4 mm.

Comparative Example A1
A seal ring having the shape shown in FIG. 10 was produced by injection molding using a resin composition containing PEEK resin as a base resin and carbon fiber and PTFE resin. The dimensions of this seal ring are an outer diameter of φ32 mm, an inner diameter of φ28 mm, a ring width of 2.3 mm, and a ring thickness of 2 mm.

Comparative Example A2
A seal ring having the shape shown in FIG. 10 was produced by injection molding using a resin composition containing PEEK resin as a base resin and carbon fiber and PTFE resin. The dimensions of this seal ring are an outer diameter of φ32 mm, an inner diameter of φ28 mm, a ring width of 2.3 mm, and a ring thickness of 2 mm. The seal ring of Comparative Example A2 has inclined portions formed on both sides of the outer peripheral surface. The inclined portion has a shape in which a surface connected perpendicularly to the side surface of the ring and a surface connected perpendicularly to the outer peripheral surface of the ring are connected by an inclined surface. The inclined portion dimension W _c _{is 0.4 mm, and the width W a} of the surface corresponding to the stepped surface of the embodiment is 0.2 mm.

<Built-in test>
The incorporateability of each of the obtained seal rings was evaluated. As shown in FIG. 5, each seal ring was inserted into the housing (tapered portion diameter R34.5 mm, tapered portion inclination angle 45 degrees) in a state of being mounted in the annular groove (depth h2.2 mm) of the rotating shaft. For each seal ring, the amount of eccentricity was changed and the ease of incorporation was evaluated in 4 stages (A to D). The case where there was no galling was evaluated as A, the case where the galling was minute was evaluated as B, the case where the galling was small was evaluated as C, and the case where the galling was large was evaluated as D. The results are shown in Table 1.

As shown in Table 1, when there was no eccentricity, galling did not occur in any of the seal rings, but the degree of galling tended to increase as the amount of eccentricity increased. When the eccentricity amount was 0.6 mm, almost no galling was observed in Examples A1 to A4, whereas large galling was observed at the corners P in Comparative Examples A1 to A2. .. Comparative Example A2 is inclined portions are formed, the inclined angle portion Q is located in the tapered portion of the housing, but since the width W _a of the stepped surface including the corner portion P is large, galling occurred. Among Examples A1 to A4, in particular, the seal ring having an inclined surface 7 having an inclination angle of 40 degrees (Example A1) and 30 degrees (Example A2) has a large eccentricity of 0.7 mm. Almost no biting was seen. In this case, the seal ring of Example A3 (inclination angle θ = 60 degrees) was slightly caught on the stepped surface, and a small galling occurred.

<Oil leak test>
The amount of oil leak of each of the obtained seal rings was evaluated by the testing machine shown in FIG. FIG. 11 is a schematic view of the testing machine. Seal rings 30 and 30'are attached to the annular groove of the mating shaft 28. As the seal ring, a seal ring before the above-mentioned assembly test was performed and a seal ring after the above-mentioned assembly test (eccentricity 0.7 mm) were used. Due to the rotation of the motor 31, the seal rings 30 and 30'are in sliding contact with the annular groove side wall of the mating shaft 28 and the inner peripheral surface of the shaft hole of the housing 29. Oil was pumped from the hydraulic unit 32 and supplied to the annular gap between the seal rings 30 and 30'. The conditions of the oil leak test were a hydraulic pressure of 800 kPa, a rotation speed of 2000 rpm, an oil temperature of 80 ° C., and ATF was used as the oil. The amount of oil leak (ml / min) was measured by this tester. The amount of oil leak is based on the value measured 5 minutes after the start of the test. The results are shown in Table 2.

As shown in Table 2, before the incorporation test, all the test examples showed almost the same amount of oil leak. On the other hand, after the incorporation test, there was almost no change in the amount of oil leak in Examples A1 and A2. As described above, since galling hardly occurred, the low oil leak property was maintained even by the incorporation. On the other hand, in Comparative Examples A1 and A2, the amount of oil leak was significantly increased by incorporating. It is considered that these seal rings had a large amount of galling due to assembly, so that the sealability with the side wall surface and the shaft hole was deteriorated. Although the amount of oil leak increased in Examples A3 to A4, it is considered that the low oil leak property is maintained depending on the amount of eccentricity (for example, eccentricity of 0.6 mm).

Example B1 to Example B3
Using PEEK resin, seal rings of each shape shown in FIG. 20 were manufactured by injection molding. The dimensions of the seal rings of Examples B1 to B3 are an outer diameter of φ43 mm, a ring width (axial length) of 2.3 mm, and a ring thickness (radial length) of 2 mm. An inclined portion is formed on the outer peripheral surface of the seal ring of each embodiment, and a concave portion is formed on the inner peripheral surface. The recess of Example B1 is an arc groove having a depth W _d of 0.06 mm (3%) and a width W _e of 0.5 mm (22%). Recess of Example B2 is trapezoidal in C arrow view, the depth _{W d} is 0.1 mm (5%), the circumferential length _{L a} is 5.5 mm, the circumferential length _{L b} is 6mm Is. The recesses were formed at four locations separated in the ring circumferential direction. The recess of Example B3 is an arc groove having a depth W _d of 0.06 mm (3%) and a width W _e of 0.9 mm (39%). The ratio in parentheses indicates the ratio to the ring thickness or the ring width. The product of the ratios is 66 in Example B1 and 117 in Example B3.

Comparative Example B1 to Comparative Example B2
Using PEEK resin, seal rings of each shape shown in FIG. 21 were manufactured by injection molding. The dimensions of the seal rings of Comparative Examples B1 to B2 are the same as those of Examples B1 to B3. Further, an inclined portion is formed on the outer peripheral surface of the seal rings of Comparative Examples B1 and B2. Comparative Example B1 does not have a recess serving as an undercut portion. Comparative Example B2 has a concave portion of a rectangular groove on the inner peripheral surface, the depth W _{d of which} is 0.3 mm (15%), and the width W _e is 0.5 mm (22%).

<Injection moldability test>
At the time of manufacturing the seal rings of Examples B1 to B3 and Comparative Examples B1 to B2, the presence or absence of sticking to the fixed side mold and the presence or absence of deformation of the product were evaluated. The presence or absence of sticking was judged by observing the injection molding process, and the presence or absence of deformation was judged by the presence or absence of a raised portion when placed on the surface plate. The mold was washed before the production of each seal ring, and each test was performed without using a mold release agent. The injection molding was continuously operated until the sticking occurred, and the number of shots in which the sticking occurred was entered in Table 3. The continuous operation was limited to 800 shots. The results are shown in Table 3.

As shown in Table 3, in Examples B1 to B3, even if injection molding was performed continuously for 800 shots, there was no sticking to the fixed side mold, and the take-out property using the take-out hand was also good. On the other hand, in Comparative Example B1 having no recess, sticking to the fixed side mold occurred at the 20th shot, and the ring was twisted (deformed). Further, in Comparative Example B2, no sticking was observed in 800 shots, but the ring was deformed at the time of taking out. Specifically, as shown in FIG. 22, in Comparative Example B2, since the recess is deeper than a predetermined depth, it is strongly caught on the core pin 63, a load is applied at the time of taking out, and the ring is deformed and the periphery of the recess is deformed. occured.

The position of the concave portion to be the undercut portion may be the ring side surface or the ring outer peripheral surface in addition to the inner peripheral surface of the ring, but in the case of the ring side surface, the anchor effect is strong even when protruding, and it is difficult to take out. Further, in the case of the outer peripheral surface of the ring, the molded body is restrained by the mold at the time of protrusion, so that the molded body does not protrude and continuous molding is difficult. Therefore, by forming the concave portion on the inner peripheral surface of the ring, as shown in FIG. 15, the molded body is not restrained at the time of taking out, and the taking out can be easily performed.

<Oil leak test>
The amount of oil leak of each of the obtained seal rings was evaluated by the testing machine shown in FIG. 23. FIG. 23 is a schematic view of the testing machine. Seal rings 75 and 75'in the shape corresponding to each test example were attached to the annular groove of the mating shaft 73. Each dimension of this seal ring has an outer diameter of φ48 mm, a ring width (axial length) of 1.6 mm, and a ring thickness (radial length) of 1.5 mm, and is heat-fixed with the abutment closed after injection molding. Was done. The above dimensions are the dimensions after heat fixing. With the mating shaft 73 fixed, the housing 74 was rotated by a motor (not shown). The seal rings 75 and 75'are in sliding contact with the annular groove side wall of the mating shaft 73 and the inner peripheral surface of the shaft hole of the housing 74. Oil was pumped from the hydraulic unit 76 and supplied to the annular gap between the seal rings 75 and 75'. The conditions of the oil leak test were a hydraulic pressure of 2.0 MPa, a rotation speed of 2000 rpm, an oil temperature of 120 ° C., and ATF was used as the oil. The amount of oil leak (ml / min) was measured by this tester. The results are shown in Table 4.

As shown in Table 4, the seal rings of Examples B1 to B3 had a low oil leak amount, and there was almost no difference in the oil leak amount. As described above, since there is no sticking to the fixed side mold and it is easy to take out from the mold, deformation of the seal ring can be suppressed and low oil leak property is maintained. On the other hand, in Comparative Example B2, the amount of oil leak was large. It is considered that this seal ring was deformed when the product was taken out, so that the sealability with the side wall surface and the inner peripheral surface of the shaft hole was deteriorated. In addition, Comparative Example B1 shown in Table 4 was tested using a seal ring in which sticking occurred. It is probable that the sticking occurred, which caused the flatness of the side surface of the ring to deteriorate, leading to an increase in the amount of oil leak.

As described above, the seal rings according to Examples B1 to B3 are sealed by forming recesses on the inner peripheral surface of the seal ring and setting the depth of the recesses to 1% to 10% of the ring thickness. It is possible to easily remove the seal ring from the mold while ensuring the same performance and depression of the ring as the conventional seal ring, and to prevent sticking to the fixed side mold and deformation accompanying it. The result is a seal ring that maintains low oil leakage.

The seal rings of the first invention and the second invention of the present application can suppress the occurrence of galling at the time of assembling the housing or the occurrence of sticking at the time of opening the mold, and can maintain low oil leakage. It can be used as a seal ring that requires low oil leakage. In particular, it can be suitably used for improving fuel efficiency in hydraulic equipment such as ATs and CVTs in automobiles and the like.

1,11

Seal ring

2,12 Ring inner

peripheral surface

3,13 Ring outer

peripheral surface

4,14

Ring side surface

5,15 Stepped

part

6,16

Inclined part

7,17

Inclined surface

8,8', 18 Stepped surface 9 Connection surface 10 Abutment 21 Rotating shaft 22 Housing 23 Fixed side mold 24 Movable side mold 25 Core pin 26 Cavity 27 Molded body 28 Mating shaft 29 Housing 30, 30'Seal ring 31 Motor 32 Hydraulic unit 51 Seal ring 52 Ring inner peripheral surface 53 Ring Outer surface 54, 54'Ring side 55, 55'Step 56 Inclined 56a

Inclined surface

57, 57A, 57B Recess 58 Stepped surface 59 Connection surface 60 Joint 61 Fixed side mold 62 Movable side mold 63 Core pin 64 Cavity 65 Molded body 66 Extraction hand 61 Rotating shaft 62 Housing 63 Mating shaft 64 Housing 65, 65'Seal ring 66 Hydraulic unit

Claims

It is mounted on an annular groove provided on a rotating shaft inserted into a shaft hole of a housing, slidably contacts a side wall surface on the unsealed fluid side of the annular groove, and contacts an inner peripheral surface of the shaft hole. A seal ring that seals the annular gap between the rotating shaft and the shaft hole.
The seal ring is an injection molded product of a resin composition, and has an inclined portion on at least one end side of the outer peripheral surface.
The inclined portion has an inclined surface connected to the ring side surface and a stepped surface connected substantially perpendicular to the outer peripheral surface, and the width of the stepped surface in the ring radial direction is 0.1 mm or less. A seal ring featuring.
The seal ring according to claim 1, wherein the inclined portion is substantially perpendicular to the side surface of the ring and has a connecting surface connecting the inclined surface and the stepped surface.
The seal ring according to claim 2, wherein the stepped surface is located inside the virtual plane on which the inclined surface is extended in the ring radial direction.
The seal ring according to claim 1, wherein the inclination angle of the inclined surface with respect to the outer peripheral surface is 20 to 60 degrees in the axial cross section of the seal ring.
The seal ring according to claim 1, wherein the seal ring has a joint of a composite step cut in a part in the circumferential direction.
The seal ring according to claim 1, wherein the base resin of the resin composition is a polyetherketone resin, a polyetheretherketone resin, a polyphenylene sulfide resin, or a polyamide-imide resin.
It is mounted on an annular groove provided on a rotating shaft inserted into a shaft hole of a housing, slidably contacts a side wall surface on the unsealed fluid side of the annular groove, and contacts an inner peripheral surface of the shaft hole. A seal ring that seals the annular gap between the rotating shaft and the shaft hole.
The seal ring is an injection-molded body of a resin composition, and has a recess in a part in the circumferential direction and a recess in the ring radial direction on the inner peripheral surface, and the depth of the recess is the seal ring. A seal ring characterized by having a length of 1% to 10% in the radial direction of the resin.
The seal ring according to claim 7, wherein the seal ring is provided with an inclined portion on at least one end side of an outer peripheral surface, and the inclined portion has an inclined surface connected to a side surface of the ring.
The seal ring according to claim 8, wherein the inclined portion has a stepped surface connected substantially perpendicular to the outer peripheral surface, and the width of the stepped surface in the ring radial direction is 0.1 mm or less. ..
The seal ring according to claim 7, wherein the width of the concave portion in the ring axial direction is 2% to 60% of the axial length of the seal ring.
The recess is a concave groove continuously provided along the ring circumferential direction, and the forming range of the concave groove in the ring circumferential direction is 15% or more with respect to the inner circumference of the seal ring. The seal ring according to claim 7.