sealing ring

Abstract

Provided is a seal ring that reduces adverse situations in a transmission, and that operates even at extremely low pressures such as water head pressure. The seal ring 1 is installed in an annular groove provided in a rotating shaft that is inserted into a shaft hole of a housing, is in free sliding contact with a side wall surface on a non-sealing fluid side of the annular groove, and is in contact with an inner peripheral surface of the shaft hole, thereby sealing an annular gap between the rotating shaft and the shaft hole, the seal ring is an annular body having a rectangular cross section, is an injection-molded body of a resin composition that contains a polyether ether ketone resin and at least one fibrous reinforcing material selected from the group consisting of carbon fibers and glass fibers, has a flexural modulus (according to ASTM D790) of 3000 MPa to 12000 MPa, and has a difference of -0.1 mm to +0.15 mm between an outer diameter dimension of the seal ring 1 in a free state and an inner diameter dimension of the housing.

Description

Technical Field

[0001] This invention relates to a sealing ring made of synthetic resin used in hydraulic equipment such as AT and CVT in automobiles and other vehicles for sealing (sealing) the working oil. Background Technology

[0002] In AT and CVT equipment, oil sealing rings used to seal the working oil are installed in critical parts. For example, a pair of separate annular grooves are installed on a rotating shaft that is inserted into a shaft hole in the housing. The side and inner circumferential surfaces of the two sealing rings receive working oil supplied from the oil passage located between the two annular grooves, while the side and outer circumferential surfaces of the opposite sides seal the sidewalls of the annular grooves and the inner circumferential surface of the housing. Each sealing surface in the sealing ring slides in contact with the sidewall of the annular groove and the inner circumferential surface of the housing, while maintaining the oil pressure of the working oil between the two sealing rings.

[0003] Conventionally, such sealing rings are made of injection-molded synthetic resin and have a generally rectangular cross-section including opposing openings (seams). One opening has a mating surface on the inner diameter side of the sealing ring, and a lip and a recessed pocket protruding from the mating surface on the outer diameter side. The other opening has a mating surface, a pocket, and a lip formed in a manner that assists in fitting with the aforementioned mating surface, lip, and pocket.

[0004] To suppress leakage under the differential pressure (water level difference pressure) caused by engine stoppage, such as during signal waiting or idling, the aforementioned sealing ring is conventionally formed such that its outer diameter is larger than the inner diameter of the housing. Specifically, the sealing ring is conventionally formed by pressing it into a constraint member of a specified shape after injection molding and then heating it, thereby making the outer diameter of the sealing ring larger than the inner diameter of the housing by a specified amount. Hereinafter, "conventionally formed (conventional forming)" will also be referred to as heat setting.

[0005] Patent Document 1 describes a sealing ring, in which the difference between the inner diameter of the housing and the outer diameter of the sealing ring, when the sealing ring is positioned before the annular gap, is increased to within 1 mm. In addition, in form 2, a sealing ring is described in which the outer diameter of the sealing ring is made to be within 1 mm smaller than the inner diameter of the housing through conventional forming processes, and is installed in an annular groove for inertial operation, or its diameter is expanded by heating to achieve close contact with the inner circumferential surface of the housing.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2009-257439 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] In embodiment 2 of patent document 1, if the sealing ring is not installed in the annular groove and operates under inertial conditions or is heated, the sealing ring will not be in close contact with the inner circumferential surface of the housing. Therefore, simply installing the sealing ring in the annular groove may lead to oil leakage under extremely low pressures, such as water level differential pressure, because the outer diameter of the sealing ring is smaller than the inner diameter of the housing.

[0011] Typically, after installation in the annular groove, if the sealing ring is heated while assembled in the housing, it will form a tight seal with the inner circumferential surface of the housing when the temperature rises. However, if the temperature drops, a gap may sometimes form between the inner circumferential surface of the housing and the outer circumferential surface of the sealing ring. For example, if the operating temperature of the sealing ring rises to 150°C (maximum operating temperature), the sealing ring will form a strong seal with the inner circumferential surface of the housing. Due to creep at this temperature, a gap may form between the inner circumferential surface of the housing and the outer circumferential surface of the sealing ring when returning to normal temperature. In this case, oil leakage may occur under extremely low pressures such as water level differential pressure, and the function will no longer be met. Therefore, it is considered that the method of sealing the sealing ring with the housing by heating, as described in Form 2 above, is sometimes unsuitable due to operating conditions.

[0012] Furthermore, in Embodiment 1 of Patent Document 1, the outer diameter of the sealing ring positioned before the annular gap is larger than the inner diameter of the housing. Therefore, even with the water level differential pressure when the engine is stopped, the tension of the sealing ring on the housing is high, resulting in sufficient sealing when it is in close contact with the sidewall of the annular groove. However, because the sealing ring is in a strongly pressed state, it may separate from the sidewall of the annular groove if the housing moves axially. In this case, the sealing ring will not function under water level differential pressure, increasing leakage of working oil and potentially causing adverse conditions during operation.

[0013] This invention was made in view of such practical circumstances, and its purpose is to provide a sealing ring that reduces adverse conditions in the transmission and operates even under extremely low pressures such as water level differential pressure.

[0014] Methods for solving problems

[0015] The sealing ring of the present invention is installed in an annular groove, which is disposed on a rotating shaft inserted into a shaft hole of a housing. The sealing ring slides freely in contact with the sidewall of the non-sealed fluid side of the annular groove and in contact with the inner circumferential surface of the shaft hole, thereby sealing the annular gap between the rotating shaft and the shaft hole. The sealing ring is characterized in that it is an annular body with a rectangular cross-section, an injection-molded body of a resin composition having an opening at one point in the circumferential direction. The resin composition is a composition comprising polyetheretherketone (PEEK) resin and at least one fibrous reinforcing material selected from carbon fiber and glass fiber. The flexural modulus of the sealing ring (according to ASTM D790) is 3000 MPa to 12000 MPa. The difference between the outer diameter (outer diameter D) of the sealing ring in its free state installed in the annular groove and the inner diameter (also called the diameter difference) of the housing is -0.1 mm to +0.15 mm.

[0016] In this specification, “flexural modulus” means the flexural modulus at room temperature (23°C) (according to ASTM D790).

[0017] The sealing ring of the present invention is characterized in that the outer diameter (outer diameter D) of the sealing ring in its free state when installed in the annular groove is larger than the outer diameter (outer diameter B) of the sealing ring in its free state before installation.

[0018] The state in which the sealing ring is not subjected to any load force in either the expansion or contraction direction is referred to as the "free state of the sealing ring". Furthermore, in this specification, the "free state of the sealing ring" without specific definition refers to the free state of the sealing ring after the injection-molded body has been heat-fixed and before it is installed in the annular groove. Additionally, the "free state of the sealing ring installed in the annular groove" refers to the free state of the sealing ring after it is installed in the annular groove and before it is inserted into the shaft hole along with the rotating shaft.

[0019] The sealing ring of the present invention is characterized in that the resin composition comprises, relative to the resin composition as a whole, 5% to 30% by mass of the fibrous reinforcing material.

[0020] The sealing ring of the present invention is characterized in that the outer diameter (outer diameter B) of the sealing ring in its free state before installation in the annular groove is 30 mm to 60 mm.

[0021] The sealing ring of the present invention is characterized in that, relative to the outer diameter of the sealing ring in its free state before being installed in the annular groove, the radial thickness and axial width of the sealing ring are 1 / 40 to 1 / 10, respectively.

[0022] The effects of the invention

[0023] The sealing ring of the present invention is installed in an annular groove of a rotating shaft that is inserted into a shaft hole in a housing, sealing the annular gap between the rotating shaft and the shaft hole. The sealing ring is an injection-molded body with a rectangular cross-section, consisting of a resin composition with an opening at one point in the circumferential direction. The resin composition comprises PEEK resin and at least one fibrous reinforcing material selected from carbon fiber and glass fiber. The flexural modulus of the sealing ring is 3000 MPa to 12000 MPa. The difference between the outer diameter of the sealing ring in its free state and the inner diameter of the housing is -0.1 mm to +0.15 mm, thus ensuring an appropriate tension between the outer circumferential surface of the sealing ring and the inner circumferential surface of the housing. Therefore, the necessary sealing performance can be achieved even under extremely low pressures (e.g., less than 5 kPa) such as water level differential pressure. Furthermore, oil leakage is suppressed even under water level differentials after operation, thus reducing adverse conditions in the transmission.

[0024] The resin composition contains 5% to 30% by mass of fibrous reinforcing material relative to the total resin composition, thus making it easy to achieve the desired flexural modulus of the sealing ring and easily control the diameter difference. Furthermore, it can improve the mechanical strength of the sealing ring.

[0025] Since the outer diameter of the sealing ring installed in front of the annular groove in its free state is 30mm to 60mm, it is easy to set the above diameter difference within the specified range.

[0026] Furthermore, since the radial thickness and axial width of the sealing ring are 1 / 40 to 1 / 10 of the outer diameter of the sealing ring in its free state when installed in front of the annular groove, it is easy to set the above-mentioned diameter difference within the specified range. Attached Figure Description

[0027] Figure 1 A three-dimensional diagram showing one form of the sealing ring.

[0028] Figure 2 This is a cross-sectional view showing the state of the sealing ring assembled into the housing.

[0029] Figure 3 This is a schematic diagram of the sealing ring being installed in the annular groove.

[0030] Figure 4 This is an enlarged view of the opening in the molded body.

[0031] Figure 5 A diagram illustrating the relationship between the sealing ring and the housing in the embodiments and comparative examples.

[0032] Figure 6 This is a schematic diagram of an oil leak detection device.

[0033] Figure 7This is an enlarged cross-sectional view of the oil leakage detection device. Detailed Implementation

[0034] To achieve the aforementioned objective, the inventors investigated a sealing ring (e.g., form 1 of Patent Document 1) whose outer diameter is larger than the inner diameter of the housing within a specified range. When this sealing ring is installed in the annular groove of a rotating shaft, its inner diameter needs to be larger than the outer diameter of the rotating shaft (expansion). The investigation revealed that by expanding the diameter during installation in the annular groove, the sealing ring undergoes plastic deformation, resulting in an increase in outer diameter of approximately 0.2 mm to 0.5 mm compared to before installation. Furthermore, with the increase in outer diameter, tension exerts its effect beyond what is expected, and it is presumed that the sealing ring will follow the housing during axial movement, potentially leading to sealing leakage. Therefore, the inventors specifically addressed the issue by focusing on the outer diameter of the sealing ring in its free state when installed in the annular groove.

[0035] based on Figure 1 One form of the sealing ring of the present invention will be described. For example... Figure 1 As shown, the sealing ring 1 is an injection-molded body of a resin composition, and is a ring-shaped body with a roughly rectangular cross-section. The corners of the inner circumferential surface 1a and the two side surfaces 2 of the sealing ring can be provided with straight or curved chamfers (corners with rounded edges). Furthermore, when manufacturing the sealing ring by injection molding, a stepped portion can be provided in this part to protrude from the mold. Additionally, the sealing ring 1 is a cut type with an opening (joint) 3 at one point in the circumference, which expands in diameter through elastic deformation and is installed in an annular groove. The opening 3 is formed by a pair of ends 31, 31'. Regarding the shape of the pair of ends 31, 31', it can also be a straight-cut type, a corner-cut type, etc.; from the perspective of excellent oil sealing performance, the shape of the end 31, 31' is preferred. Figure 1 The composite step-cut type shown.

[0036] Figure 1 The sealing ring 1 shown is brought to a closed state by heat fixation, as described later. The size of the sealing ring 1 (outer diameter, inner diameter, axial width, radial thickness, etc.) is appropriately set according to the application. For example, the inner diameter of the sealing ring 1 is 12 mm to 75 mm, and the outer diameter B of the sealing ring 1 in its free state is 15 mm to 80 mm. More preferably, the outer diameter B is 30 mm to 60 mm.

[0037] Furthermore, the radial thickness and axial width of the sealing ring 1 can be, for example, 1 / 40 to 1 / 10 of the outer diameter B. As will be described later, the outer diameter of the sealing ring changes before and after installation in the annular groove (dimension B → dimension D). By keeping the radial thickness and axial width within the aforementioned range, it is easy to stabilize the rate of change of the outer diameter and to easily set the difference (diameter difference) between the outer diameter and the inner diameter of the housing within a specified range. Furthermore, the aforementioned radial thickness and axial width are preferably 1 / 30 to 1 / 15 of the outer diameter B.

[0038] based on Figure 2 A brief description of an example of the use of the sealing ring is provided. The sealing ring 1 is installed in an annular groove 4a, which is located on a rotating shaft 4 that is inserted into a shaft hole 5a in the housing 5. The arrows in the figure indicate the direction of pressure applied from the working oil; the right side of the figure represents the non-sealed fluid side. The sealing ring 1 slides freely in contact with the sidewall 4b of the non-sealed fluid side of the annular groove 4a on its sealing ring side 2. Furthermore, its outer circumferential surface 1b contacts the inner circumferential surface of the shaft hole 5a. This sealing structure seals the annular gap between the rotating shaft 4 and the shaft hole 5a. Additionally, a suitable type of working oil appropriate for the application is used. For example, it is used under conditions of an oil temperature of approximately -30 to 150°C, an oil pressure of approximately 0 to 3.0 MPa, and a rotating shaft speed of approximately 0 to 7000 rpm.

[0039] Secondly, refer to Figure 3 An example using a sealing ring is used to illustrate the diameter difference. Figure 3 (a) indicates the dimensional relationship between the sealing ring installed before the annular groove and the housing. Figure 3 (b) shows the process diagram for installing the sealing ring into the annular groove. Figure 3 (c) indicates the dimensional relationship between the sealing ring installed in the annular groove and the housing. Figure 3 In (a), the outer diameter B of the sealing ring 1 in its free state is smaller than the inner diameter φ of the housing 5. After the sealing ring 1 is expanded by the tapered clamp 6 (refer to...), Figure 3 (b)), fitted into the annular groove 4a (see reference) Figure 3 (c) Due to plastic deformation during expansion, the outer diameter D of the sealing ring 1 installed in the annular groove 4a in its free state is larger than the outer diameter B of the sealing ring 1 installed in front of the annular groove 4a in its free state (D>B).

[0040] In this invention, the sealing ring 1 is characterized in that the difference between its outer diameter D and the inner diameter φ of the housing 5, i.e., (D-φ), is -0.1mm to +0.15mm. When the outer diameter D of the sealing ring 1 is larger than the inner diameter φ of the housing 5 (refer to...), the sealing ring 1 is further characterized by a diameter difference of -0.1mm to +0.15mm. Figure 3(c)) The diameter difference becomes a positive value. When the outer diameter D of the sealing ring 1 is smaller than the inner diameter φ of the housing 5, the diameter difference becomes a negative value.

[0041] In order to ensure the sealing ring operates and seals the working oil even under water level differential pressure when the engine is stopped, it is ideal for the diameter difference between the outer diameter of the sealing ring and the inner diameter of the housing to be zero when installed in the annular groove. However, it is practically difficult to control the diameter difference to zero. Therefore, in this invention, by making the diameter difference -0.1 mm to +0.15 mm, the sealing ring can operate even under water level differential pressure, and excellent sealing performance can be obtained. From the viewpoint of sealing performance, the diameter difference is preferably -0.05 mm to +0.1 mm, and more preferably +0.05 mm to +0.1 mm.

[0042] The aforementioned diameter difference, taking into account the increase in outer diameter due to plastic deformation, is obtained by using heat-fixing to control the outer diameter B of the sealing ring. The rate of change of the outer diameter of the sealing ring of the present invention before and after installation in the annular groove ((DB) / B×100) is preferably +0.1% to +0.5%, more preferably +0.2% to +0.4%.

[0043] The sealing ring of the present invention is obtained by the following steps 1 and 2.

[0044] Process 1: Molding process

[0045] In the molding process, molding granules obtained by melt-blending a resin composition are used to obtain a molded body using a known injection molding method. Furthermore, details regarding the resin composition will be described later. In stage 1, as... Figure 4 As shown in (a), the opening 3 of the molded body is in an open state. Figure 4 In (a), the opening 3 of the molded body is a composite stepped cut. In the opening 3, one end 31 has a mating portion 31a on the inner circumferential side, a lip 31b protruding from the mating portion 31a on the outer circumferential side, and a retracted pocket portion 31c. The other end 31' has a mating portion 31a', a pocket portion 31c', and a lip 31b' formed in a manner that complements and fits into the mating portion 31a, the lip 31b, and the pocket portion 31c. Figure 4 In (a), a pair of lips 31b and 31b' are separated from each other, becoming a state in which they do not overlap in the radial direction of the molded body.

[0046] Process 2: Heat setting process

[0047] Next, the molded body is heat-fixed with the opening closed after injection molding, so that the outer diameter of the sealing ring becomes a perfect circle. Specifically, first, the gap between the openings of the molded body is narrowed, and the inner diameter of a cylindrical heat-fixing tube is pressed in. The cylinder is then inserted into the inner diameter of the pressed-in molded body. Then, it is exposed to a high-temperature atmosphere for a certain period of time, causing the cylinder to expand, thereby applying a forced force from the inside of the molded body for heat fixing. As a result, the opening 3 of the molded body becomes closed. Figure 4 (b)). The molded body after heat setting is equivalent to Figure 1 The sealing ring. Because the opening 3 is closed, the outer diameter B of the molded body is smaller than the outer diameter A of the injection-molded body (A > B).

[0048] Next, the sealing ring obtained above is installed in the annular groove of the rotating shaft. Specifically, as shown... Figure 3 As shown in (b), the sealing ring 1 is inserted into the tapered clamp 6 for mounting on the rotating shaft 4. While expanding the diameter of the sealing ring 1, it is moved towards the annular groove 4a of the rotating shaft 4 and mounted on the annular groove 4a. The outer diameter C of the sealing ring during this expansion is larger than the outer diameter A after injection molding (C > A). In addition, the outer diameter D of the sealing ring mounted on the annular groove 4a is smaller than the outer diameter C during expansion (C > D), and larger than the outer diameter B after heat curing (D > B). If the size relationship of the outer diameter of each of the above processes is summarized, it becomes C > A > D > B.

[0049] In this invention, the difference between the outer diameter D and the inner diameter φ of the housing is -0.1 mm to +0.15 mm. Furthermore, the outer diameter D is preferably -0.25% to +0.35% larger than the inner diameter φ of the housing. For example, to make the outer diameter D fall within this range, it is preferable that the outer diameter B is -0.60% to +0.15% larger than the inner diameter φ of the housing.

[0050] The sealing ring of the present invention has a flexural modulus of 3000MPa to 12000MPa as measured by ASTM D790. By making the flexural modulus below 12000MPa, it is easy to stabilize the change in outer diameter dimension B to outer diameter dimension D, and it is easy to control the diameter difference with the inner diameter dimension φ of the shell within the range of -0.1mm to +0.15mm.

[0051] On the other hand, if the flexural modulus is less than 3000 MPa, the sealing ring will thermally expand at the operating temperature of the transmission (above 120°C), potentially deforming in the direction of elongation of the total length and narrowing of the opening. This is because the outer circumferential surface of the sealing ring is constrained by the inner circumferential surface of the housing, so the thermal expansion is not radial but circumferential. Even if the sealing ring, which has expanded circumferentially, is cooled due to operation stopping and its total length returns to its original length, its shape cannot return to its original shape. Therefore, creep occurs in the state of narrowing of the opening, resulting in the outer diameter of the sealing ring becoming further smaller than the outer diameter D, for example, by 0.1 mm or more. Consequently, the sealing performance during subsequent operation may decrease. However, the flexural modulus of the sealing ring of the present invention is 3000 MPa or more, thus suppressing circumferential deformation during operation.

[0052] The flexural modulus of the sealing ring is preferably 3000MPa to 10000MPa, and more preferably 5000MPa to 10000MPa.

[0053] The resin composition used in this invention is a composition comprising PEEK resin as a base resin and at least one fibrous reinforcing material selected from carbon fiber and glass fiber. The amount of PEEK resin relative to the total resin composition is preferably 70% to 95% by mass, more preferably 80% to 95% by mass.

[0054] Furthermore, the amount of fibrous reinforcing material incorporated relative to the total resin composition is preferably 5% to 30% by mass. By keeping the amount of fibrous reinforcing material within this range, the flexural modulus can be easily made to the desired value. The amount of fibrous reinforcing material is more preferably 5% to 15% by mass.

[0055] Carbon fibers can be either pitch-based or PAN-based, classified by raw material type. There is no particular limitation on the firing temperature; however, carbonized products fired at around 1000–1500°C are less prone to annular groove wear even at high PV levels compared to graphitized products fired at 2000°C or higher, and are therefore preferred. Furthermore, carbon fibers can be either chopped fibers or ground fibers; ground fibers are preferred due to their higher fiber count at the same blending ratio and ease of oil film formation.

[0056] There is no particular limitation on the average fiber diameter of the fibrous reinforcing material, but it is preferably 20 μm or less. If the fiber diameter exceeds this range, the wear loss of the annular groove may increase if the shaft material is aluminum alloy or unquenched steel. In addition, in order to ensure the expansion of the sealing ring while achieving good reinforcement effect, the average fiber length of the fibrous reinforcing material is preferably 0.02 mm to 0.2 mm.

[0057] In the above resin composition, polytetrafluoroethylene (PTFE) resin, graphite, molybdenum disulfide and other solid lubricants, calcium phosphate, calcium sulfate and other sliding reinforcement materials, carbon black and other materials may be added as needed.

[0058] Furthermore, the rotating shaft of the present invention has an annular groove on its outer circumferential surface, and the aforementioned sealing ring is installed in the annular groove, which is inserted into the shaft hole of the housing. Specifically, the sealing ring is an annular body with a rectangular cross-section, and is an injection-molded body of a resin composition having an opening at one point in the circumferential direction. The resin composition is a composition containing PEEK resin and at least one fibrous reinforcing material selected from carbon fiber and glass fiber. The flexural modulus of the sealing ring is 3000MPa to 12000MPa, and the difference between the outer diameter of the sealing ring in its free state and the inner diameter of the housing is -0.1mm to +0.15mm.

[0059] Example

[0060] The following shows the raw materials of the resin composition constituting the sealing rings of the embodiments and comparative examples, the flexural modulus of the sealing rings, and the inner diameter of the housing of the device used in the tests.

[0061] Base resin of the resin composition: PEEK resin

[0062] Filler material in the resin composition: 10% by weight of carbon fiber + others

[0063] Flexural modulus: 7000MPa

[0064] Inner diameter of the housing: φ44mm

[0065] Using a resin composition derived from the aforementioned raw materials, a pellet was produced by melt mixing using a twin-screw extruder. This pellet was then used as raw material for injection molding to obtain a molded body. The resulting molded body was then heat-cured to obtain sealing rings with different outer diameters, each with a radial thickness of 2 mm and an axial width of 2.3 mm. Specifically, during heat curing, 10 different sealing rings (Examples 1-5, Comparative Examples 1-5) were produced by using heat-curing tubes with different inner diameters, resulting in a different outer diameter B within ±0.30 mm of a center of 44 mm.

[0066] The manufactured sealing ring was installed in the shaft groove (annular groove) of the oil leakage testing device described later using a conical clamp, and a test was conducted. Furthermore, the outer diameter D of the installed sealing ring was measured, and the diameter difference and the rate of change of the outer diameter were calculated. The dimensions of Examples 1 to 5 are shown in Table 1. Additionally, in Figure 5 The dimensions of the sealing ring and the housing are shown in Examples 1, 2, 4 and Comparative Example 2.

[0067] [Table 1]

[0068]

[0069] As shown in Table 1, the difference between the outer diameter D of the sealing ring and the inner diameter φ of the housing after installation in Examples 1-5 is -0.1mm to +0.15mm. Compared with before installation, the outer diameter of the sealing ring in Examples 1-5 increases by 0.09mm to 0.15mm after installation, and the change rate of the outer diameter is 0.20% to 0.34%.

[0070] Furthermore, ratio a in Table 1 represents the ratio of the difference between the outer diameter B and the inner diameter φ of the sealing ring relative to the inner diameter φ of the housing, and ratio b in Table 1 represents the ratio of the difference between the outer diameter D and the inner diameter φ of the sealing ring relative to the inner diameter φ of the housing. From this result, it can be seen that in order to make ratio b range from -0.23% to +0.34%, the sealing ring needs to be manufactured with a difference of -0.57% to +0.14% relative to ratio a.

[0071] (1) Water level differential pressure oil leakage test

[0072] To evaluate oil leakage under water level differential pressure of the sealing ring, use Figure 6 and Figure 7 The oil leakage detection device shown was tested under the following conditions and procedures. Among them, Figure 6 This is a schematic diagram of an oil leak detection device. Figure 7 This is an enlarged cross-sectional view of the sealing ring installed in the annular groove and the periphery of the housing.

[0073] Oil leakage test conditions

[0074] Oil: ATF

[0075] Test temperature: 40℃

[0076] Speed: 0 rpm

[0077] The following is based on Figure 6 and Figure 7 The steps of this experiment will be explained.

[0078] 1-1: With valve 1 closed, open valve 2 and apply oil pressure (50 kPa, 1 minute) using a pump to move the sealing ring so that it is in close contact with the right side wall of the annular groove (working state).

[0079] 1-2: Next, valve 2 was closed and valve 1 was opened, and the oil leakage rate under the water level differential pressure (2.4 kPa) was measured. In terms of oil leakage, cases with an oil leakage rate of less than 1 cc / minute were judged as "○", and cases with an oil leakage rate of more than 1 cc / minute were judged as "×".

[0080] 1-3: Under the condition of applied water level differential pressure, such as Figure 7 As shown, tighten the nut to move the housing to the left (axially) and determine whether the sealing ring is engaged. For example, if the sealing ring follows the housing's movement, it separates from the right sidewall of the annular groove, creating a gap in the sealing surface and increasing oil leakage. Conversely, if the sealing ring does not follow the housing, the oil leakage does not increase, indicating that the sealing ring is engaged. Thus, by observing the increase in oil leakage when the housing is moved, the engagement of the sealing ring can be determined. The results are shown in Table 2.

[0081] (2) Oil pressure leakage test (working pressure test)

[0082] For the sealing rings that did not work under the water level differential pressure in the above (1) test (Comparative Examples 4-5), the working pressure was measured by applying oil pressure with a pump.

[0083] The following is based on Figure 6 and Figure 7 The steps of this experiment will be explained.

[0084] 2-1: With valve 1 closed, open valve 2 and apply oil pressure (50 kPa, 1 minute) using a pump to move the sealing ring so that it is in close contact with the right side wall of the annular groove (working state).

[0085] 2-2: Next, set the oil pressure generated by the pump to 3 kPa. Under this oil pressure, such as... Figure 7 As shown, tighten the nut to move the housing to the left of the figure, and observe the increase in oil leakage. With the increase in oil leakage, the sealing ring did not function at this oil pressure, so the oil pressure was further increased by 1 kPa, and the increase in oil leakage was observed again. Then, the oil pressure was increased by 1 kPa each time until the sealing ring functioned, and the final oil pressure at which the sealing ring functioned was taken as the working pressure. The results are shown in Table 2.

[0086] Furthermore, in Table 2, for sealing rings operating under differential water pressure (Examples 1-5, Comparative Examples 1-3), the operating pressure gauge is recorded as 2.4 kPa or less.

[0087] [Table 2]

[0088]

[0089] As shown in Table 2, the sealing rings of Examples 1 to 5 function even under water level differential pressure, and therefore exhibit good oil leakage performance. It can be seen that the oil leakage under water level differential reaches its peak when the diameter difference is 0.05 mm or more. From the viewpoint of oil leakage performance, a diameter difference of 0.05 mm or more is preferred.

[0090] On the other hand, the sealing rings of Comparative Examples 1-3 (whose outer diameter D was 0.15 mm to 0.3 mm smaller than the inner diameter φ of the housing) operated under water level differential pressure, but this resulted in increased oil leakage. Furthermore, the sealing rings of Comparative Examples 4-5 (whose outer diameter D was 0.2 mm to 0.3 mm larger than the inner diameter φ of the housing) had low oil leakage under water level differential pressure, but they placed a heavy load on the housing, resulting in them not operating under water level differential pressure. Therefore, it is believed that the sealing rings of Comparative Examples 4-5, for example, would experience increased working oil leakage if the housing moved axially under a water level differential pressure.

[0091] Based on the above, the sealing ring of the present invention, after being made into a specified resin composition and a specified flexural modulus, further makes the diameter difference between the outer diameter D of the sealing ring installed in the annular groove and the inner diameter φ of the housing less than +0.15 mm, thereby reducing the load on the housing and enabling it to work even under differential pressure of water level and perform sealing performance. At the same time, by making the diameter difference more than -0.1 mm, the gap with the inner circumferential surface of the housing is reduced, ensuring good sealing performance.

[0092] Industrial availability

[0093] The sealing ring of this invention operates even under differential pressure, maintaining its sealing performance. Furthermore, it suppresses oil leakage even under differential pressure after operation, thus reducing adverse conditions in the transmission. The sealing ring of this invention is suitable for use as a sealing ring for the rotating shaft of hydraulic equipment such as AT and CVT transmissions.

[0094] Explanation of reference numerals in the attached figures

[0095] 1. Sealing ring

[0096] 2. Side of the sealing ring

[0097] 3 Openings

[0098] 4. Rotation axis

[0099] 5. Housing

[0100] 6 Conical clamps

Claims

1. A sealing ring, wherein the sealing ring is installed in an annular groove disposed on a rotating shaft inserted into a shaft hole in a housing, the sealing ring being in free sliding contact with the sidewall of the non-sealed fluid side of the annular groove and in contact with the inner circumferential surface of the shaft hole, thereby sealing the annular gap between the rotating shaft and the shaft hole, characterized in that, The sealing ring is a ring-shaped body with a rectangular cross-section, and is an injection-molded body of a resin composition with an opening at one point in the circumferential direction. The resin composition is a composition comprising polyetheretherketone resin and at least one fibrous reinforcing material selected from carbon fiber and glass fiber. The flexural modulus of the sealing ring is 3000MPa to 12000MPa according to ASTM D790. The difference between the outer diameter of the sealing ring installed in the annular groove in its free state and the inner diameter of the housing is -0.1 mm to +0.15 mm.

2. The sealing ring according to claim 1, characterized in that, The outer diameter of the sealing ring installed in the annular groove in its free state is larger than the outer diameter of the sealing ring in its free state before installation.

3. The sealing ring according to claim 1, characterized in that, The resin composition comprises, relative to the total resin composition, 5% to 30% by mass of the fibrous reinforcing material.

4. The sealing ring according to claim 1, characterized in that, The outer diameter of the sealing ring installed before the annular groove in its free state is 30mm to 60mm.

5. The sealing ring according to claim 1, characterized in that, The radial thickness and axial width of the sealing ring are 1 / 40 to 1 / 10, respectively, relative to the outer diameter of the sealing ring in its free state before being installed in the annular groove.

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