Flow control valve seal

Abstract

The present invention provides a flow control valve seal that combines low torque characteristics with good sealing performance. A seal 7A is a flow control valve seal that slides against a rotor 6 (mating member) with an interference fit, and comprises a sliding portion 8 that slides against the rotor 6 and a body portion 9 that presses the sliding portion 8 against the rotor 6, the seal 7A being an integrally molded product of the sliding portion 8 and the body portion 9. The sliding portion 8 comprises an ultra-high molecular weight polyethylene resin composition, the body portion 9 comprises a rubber composition, and the seal 7A is pressed with an interference fit of 5-25% in the axial direction relative to the maximum axial length of the seal 7A.

Description

Seals for flow control valves

[0001] This invention relates to a seal for a flow control valve.

[0002] Automobiles are equipped with circulation channels to circulate coolant and cool various parts of the vehicle. These circulation channels may consist of multiple channels, such as a channel that circulates coolant to the radiator and a channel that circulates coolant to the heater core of the air conditioner. Flow control valve devices are placed within these circulation channels to control the flow rate of the coolant, and these valve devices adjust the flow rate of the coolant in each channel.

[0003] For example, Patent Document 1 discloses a sealing device that seals the space between a valve body, which is movably arranged within a valve casing to control the flow of fluid, and a pipe connected to or part of the valve casing through which fluid flows. This sealing device is described to include a first sealing portion, which is an annular plate or membrane made of resin that is in close contact with the outer surface of the valve body, and a second cylindrical sealing portion, which is made of a more flexible material than the first sealing portion, and which contacts the inner or outer surface of the pipe to prevent fluid leakage from the pipe.

[0004] Furthermore, Patent Document 2 describes a valve housing having an inlet on the upstream side in the direction of water flow and an outlet on the downstream side, a spherical valve having a valve inlet and a valve outlet and being rotated by a motor, and a sealing member having a circumferential main lip and a concentric outer sub-lip, wherein the sealing member is positioned between the inlet and the spherical valve within the valve housing, the main lip and sub-lip of the sealing member abut against the spherical valve, and a circumferential void reservoir is formed between the spherical valve and the main lip and sub-lip of the sealing member, and the main lip is formed on a portion that protrudes inward from the cylindrical inner circumferential wall of the sealing member.

[0005] International Publication No. 2018 / 066424, Japanese Patent Publication No. 2015-218775

[0006] In recent years, with increasingly stringent regulations on fuel efficiency for automobiles, the installation of flow control valve devices that adjust the flow rate and flow path of coolant is progressing in order to improve fuel efficiency by increasing thermal efficiency. As a seal for the flow control valve used in this device, for example, Patent Document 1 describes that the first sealing portion that is in close contact with the outer surface of the valve body is formed of polytetrafluoroethylene (PTFE) resin. However, although PTFE resin has excellent sliding properties, its wear resistance is not sufficient. Patent Document 2 describes that the sealing member that abuts against the spherical valve is formed of ethylene propylene rubber (EPDM) or hydrogenated nitrile rubber (HNBR). However, rubber materials have poor sliding properties and may result in high frictional resistance.

[0007] This invention has been made in view of these circumstances, and aims to provide a seal for a flow control valve that combines low torque and good sealing performance.

[0008] The flow control valve seal of the present invention (hereinafter also simply referred to as "seal") is a flow control valve seal that slides against a mating member with an overlap, and comprises a sliding portion that slides against the mating member and a main body portion that presses the sliding portion against the mating member, and is an integrally molded product of the sliding portion and the main body portion, the sliding portion is made of an ultra-high molecular weight polyethylene (PE) resin composition and the main body portion is made of a rubber composition, and is characterized in that it has an overlap of 5% to 25% in the axial direction with respect to the mating member with respect to the maximum axial length of the flow control valve seal. In this specification, ultra-high molecular weight PE resin refers to a resin in which the molecular weight of PE resin, which is normally 20,000 to 300,000, has been increased to about 500,000 to 15,000,000. Furthermore, the configuration including the flow control valve seal and the mating member is referred to as a sealing device.

[0009] The sliding portion described above is characterized by being in the form of a sheet with a thickness of 0.05 mm or more and 0.3 mm or less.

[0010] The main body is made of EPDM and is characterized by being integrated with the sliding part without the use of adhesive.

[0011] The hardness of the main body is characterized by being 40° or more and less than 70°. Furthermore, the hardness of the main body is characterized by being less than the hardness of the sliding part, and the difference in their hardness is within 20°. In this specification, hardness refers to Type D durometer hardness, which is determined by the method specified in JIS K 6253-3.

[0012] The seal for a flow control valve of the present invention has a sliding portion that slides against a mating member and a main body portion that presses the sliding portion against the mating member. The sliding portion and the main body portion are integrally molded, and since the sliding portion is made of an ultra-high molecular weight PE resin composition, it has superior wear resistance compared to the case where the sliding portion is made of, for example, PTFE resin. Furthermore, it has superior sliding properties compared to rubber materials and can suppress torque increase due to sliding against the mating member.

[0013] Furthermore, the main body is made of a rubber composition, and the seal for the flow control valve has an axial overlap of 5% to 25% of the maximum axial length of the seal. This allows the main body to press against the sliding part, causing the sliding part to adhere tightly to the mating member, thus providing excellent sealing performance. In addition, since the main body also functions as a coil spring, it may be possible to eliminate the need for a separate coil spring used with the seal, which could lead to a smaller overall device.

[0014] Since the sliding portion is in the form of a sheet with a thickness of 0.05 mm to 0.3 mm, it prevents wear and tear of the sliding portion while easily conforming to the surface shape of the mating member, thus providing good sealing performance.

[0015] The main body is made of EPDM, and since its molecular structure (ethylene structure) is the same as that of the ultra-high molecular weight PE resin that constitutes the sliding part, it can be molded as a single piece without the need for adhesive. Therefore, it offers excellent manufacturing efficiency, and the direct bonding between the sliding part and the main body results in superior conformability to the shape of the mating component.

[0016] The hardness of the main body is between 40° and 70°, and is also lower and more flexible than the hardness of the sliding part, resulting in excellent deformability and superior conformability to the shape of the mating member.

[0017] This is a schematic cross-sectional view showing an example of a flow control valve device equipped with a seal for a flow control valve according to the present invention. This is a perspective view showing an example of a seal for a flow control valve according to the present invention. This is a schematic diagram of a friction and wear testing machine. This is a schematic diagram of a leak testing machine.

[0018] An example of a flow control valve device (hereinafter also simply referred to as "valve device") to which the flow control valve seal of the present invention is applied will be described with reference to Figure 1. As shown in Figure 1, the valve device 1 comprises a housing 2, a rotating shaft 5 rotatably supported relative to the housing 2, a rotor 6 housed within the housing 2 and rotating integrally with the rotating shaft 5, and seals 7A, 7B, and 7C that slide against the outer circumferential surface 6a of the rotor 6. These seals 7A, 7B, and 7C each correspond to the flow control valve seal of the present invention. The rotating shaft 5 is connected to a motor (not shown).

[0019] The housing 2 has an inlet 3 for receiving coolant from the engine and other components, and discharge sections 4A, 4B, and 4C for sending coolant to various devices such as radiators. In Figure 1, the valve device 1 has a three-way fluid flow path and is provided with three cylindrical discharge sections. In the valve device 1, seals 7A, 7B, and 7C are fitted to the inner circumferential surfaces 2a of each discharge section 4A, 4B, and 4C, respectively.

[0020] In the valve device 1, a seal is not installed on the inner circumferential surface of the inlet section 3, but a seal may be installed on the inlet section in addition to the discharge section.

[0021] The rotor 6 is a rotating rotor with a hollow section inside, and its outer surface 6a, which slides against the seals 7A, 7B, and 7C, is formed in a cylindrical shape. The rotor 6 has a rotor opening 6b that penetrates from the inside to the outside, and the seals 7A, 7B, and 7C have seal openings that penetrate through to the center. The rotating shaft 5 rotates in the direction of the arrow, and the rotor 6 rotates accordingly. This rotation causes the rotor opening 6b and the seal opening to communicate, resulting in an open valve state, and the rotor opening 6b and the seal opening to become disconnected, resulting in a closed valve state. In the open valve state shown in Figure 1, cooling water introduced from the inlet 3 of the housing 2 is supplied from the rotor 6 through the respective discharge sections 4A, 4B, and 4C to the cooling parts such as the battery. In this way, the opening and closing of the valve device 1 can be controlled by rotating the rotor 6, thereby adjusting the flow rate and distribution of cooling water.

[0022] The material of the rotor 6 is not particularly limited, but is, for example, made of resin, and more specifically, is an injection-molded article of a resin composition with a thermoplastic resin as the base resin. The thermoplastic resin is not particularly limited, but it is preferable to use a thermoplastic resin other than fluororesin, for example, polyphenylene sulfide (PPS) resin, polyamide (PA) 66 resin, semi-aromatic PA resin, polyether ether ketone (PEEK) resin, etc. As for semi-aromatic PA resins, PA9T resin and PA10T resin, which have low water absorption rates, are preferred. Among these resins, PPS resin is more preferred because it has low water absorption, excellent heat resistance and alkali resistance, and is inexpensive.

[0023] Furthermore, it is preferable to incorporate glass fibers into the resin composition used for the rotor 6 in order to obtain high strength, high elasticity, and high dimensional accuracy. PPS resin with glass fibers incorporated is even more preferable because it has excellent high strength and high elasticity. When glass fibers are incorporated, the amount is 10% to 50% by mass of the total resin composition, preferably 20% to 40% by mass. If the amount of glass fibers is greater than the predetermined amount, the seal will be more prone to wear and damage, and if it is less, it will be difficult to obtain sufficient strength. In addition, to eliminate anisotropy in molding shrinkage and improve dimensional accuracy, glass fibers and non-fibrous fillers may be used in combination in this resin composition.

[0024] In the housing 2, the inner circumferential surfaces 2a of the discharge sections 4A, 4B, and 4C are made of resin, for example, and more specifically, are molded from a resin composition with a thermoplastic resin as the base resin. The thermoplastic resin is not particularly limited, but for example, PPS resin, PA66 resin, semi-aromatic PA resin, PEEK resin, etc. can be used. Among these resins, PA66 resin is preferred because it has excellent alkali resistance and is inexpensive.

[0025] Seal 7A (and similarly seals 7B and 7C) is a one-piece molded product in which the sliding part 8 and the main body 9 are made of different materials and integrated together. The method of integration is not particularly limited; the sliding part 8 may be directly bonded to the surface of the main body 9, or they may be bonded with an adhesive or the like interposed between them. Seal 7A is installed with the sliding part 8 in contact with the outer circumferential surface 6a of the rotor 6, with a predetermined overlap. The sliding part 8 is pressed against the rubber main body 9. The overlap can be adjusted by pressing a separate component such as a spacer or coil spring, or the inner wall of a housing or pipe, against the end face of the main body 9 of seal 7A.

[0026] The seal for a flow control valve of the present invention will be described with reference to Figure 2. In the present invention, the direction along the central axis O of the seal is called the axial direction, the direction perpendicular to the central axis O in a plan view from the axial direction is called the radial direction, and the direction that circles around the central axis O in the same plan view is called the circumferential direction. In Figure 2, the seal 7A is used for the explanation, but the same applies to seals 7B and 7C.

[0027] Figure 2(a) is a perspective view of a seal for a flow control valve, and Figure 2(b) is a side view seen from one direction (the side of the retracted portion 71a). The seal 7A is a cylindrical member and has a front end surface 71 and a rear end surface 72 as axial end surfaces, with a seal opening formed inside that penetrates axially. The front end surface 71 is a sliding contact surface that slides against the outer circumferential surface of the mating member and is composed of a sliding portion 8.

[0028] The leading edge surface 71 of the seal 7A slides against the outer circumferential surface of the mating member, and thus an annular sealing region is formed. The side shape of this sealing region along the central axis O of the seal 7A is formed as an arc-shaped curved surface corresponding to the shape of the mating member (see Figure 2(b)). This arc-shaped curved surface is formed with a predetermined radius of curvature. The sealing region has a recessed portion 71a that is closest to the rear end surface 72, and on both sides of this recessed portion 71a, there are protruding portions 71b that extend in an arc shape along the shape of the outer circumferential surface of the mating member. The two protruding portions 71b are formed at opposing positions in the circumferential direction of the seal 7A and are sandwiched between the two recessed portions 71a in the circumferential direction. The axial length of the protruding portion 71b from the rear end surface 72 of the seal 7A is longer than the length to the recessed portion 71a.

[0029] The rear end surface 72 of the seal 7A is formed by a plane perpendicular to the axial direction. For example, a spacer or a coil spring will come into contact with this rear end surface 72.

[0030] The inner circumferential surface 73 of the seal 7A is formed by a straight cylindrical inner surface parallel to the axial direction. The outer circumferential surface 74 of the seal 7A is formed by a straight cylindrical outer surface parallel to the axial direction. A circumferential protrusion or the like may be provided to seal the gap between the outer circumferential surface of the seal and the inner circumferential surface of the housing. Alternatively, when the seal is pressed in the axial direction, the elasticity of the seal body causes the seal to deform and expand in the circumferential direction, thus performing a function equivalent to that of the circumferential protrusion.

[0031] Figure 2(c) shows a cross-sectional view of the seal 7A along line A-A. In Figure 2(c), the tip surface 71 of the seal 7A has a substantially semicircular cross-sectional shape in the axial direction and has a predetermined radius of curvature. This substantially semicircular cross-sectional shape is continuously formed in the circumferential direction, and the cross-sectional shape at any circumferential position of the seal 7A is substantially semicircular. Note that this cross-sectional shape is not limited to a substantially semicircular shape, but may also be trapezoidal, triangular, or other shapes.

[0032] In Figure 2(c), the sliding portion 8 of the seal 7A is shown as a black-painted area. The sliding portion 8 has a predetermined thickness and is provided to cover the tip surface of the cylindrical rubber body portion 9. In other words, the sliding portion 8 constitutes the part that slides against the mating member. On the other hand, the sliding portion 8 is not provided on other parts of the body portion 9, and the body portion 9 is exposed on the rear end surface 72, inner circumferential surface 73, and outer circumferential surface 74 of the seal 7A.

[0033] The sliding part 8 is formed from an ultra-high molecular weight PE resin composition. The ultra-high molecular weight PE resin composition is a resin composition mainly composed of ultra-high molecular weight PE resin, and contains 50% by mass or more of ultra-high molecular weight PE resin. The content of ultra-high molecular weight PE resin in the ultra-high molecular weight PE resin composition may be 80% by mass or more, 90% by mass or more, or even just ultra-high molecular weight PE resin (100% by mass).

[0034] Furthermore, the ultra-high molecular weight PE resin may be a homopolymer of ethylene, or a copolymer of ethylene and another monomer copolymerizable with ethylene. The content of ethylene-derived constituent units in the ultra-high molecular weight PE resin is preferably 80 mol% or more, and more preferably 90 mol% or more. Examples of other monomers copolymerizable with ethylene include α-olefins having 3 or more carbon atoms (such as propylene and 1-butene).

[0035] Ultra-high molecular weight PE resins have low friction properties and, due to their high molecular weight, exhibit good wear resistance (especially against rough wear). The weight-average molecular weight of ultra-high molecular weight PE resins is, for example, 1 million to 6 million, and preferably 1 million to 4 million. Within this range, it is possible to obtain an improved wear resistance while also achieving excellent thin-wall moldability. However, among ultra-high molecular weight PE resins, those with a molecular weight of 1 million or more have extremely high viscosity when melted and hardly flow at all. Therefore, they cannot be molded using conventional injection molding methods as a base resin. Typically, the material is molded by heat compression molding or ram extrusion molding, and then processed into the desired shape (e.g., sheet) by machining.

[0036] It is preferable that the sliding portion 8 is in a sheet shape. For example, a sheet or film of an ultra-high molecular weight PE resin composition having a predetermined thickness is integrated with the main body portion 9.

[0037] The thickness of the sliding portion 8 is not particularly limited. However, in consideration of wear caused by sliding contact with the mating member, the thickness is preferably 0.05 mm or more, and may be 0.1 mm or more. On the other hand, when the thickness of the sliding portion 8 increases, the rigidity of the sliding portion 8 increases, which makes it difficult to follow the surface shape of the mating member and may result in decreased sealing performance. From this point of view, the thickness of the sliding portion 8 is preferably 0.5 mm or less, and more preferably 0.3 mm or less.

[0038] As a specific range, the thickness of the sliding portion 8 is preferably 0.05 mm or more and 0.3 mm or less. This makes it easy to achieve both wear resistance and sealing performance of the seal 7A. In the sliding portion 8, the thickness thereof may be constant in the circumferential direction and the radial direction. Note that the thickness of the sliding portion 8 may be varied in the circumferential direction and the radial direction in consideration of sliding with the mating member. For example, the thickness on the outer diameter side of the sliding portion 8 may be greater than the thickness on the inner diameter side.

[0039] The hardness of the sliding portion 8 is, for example, 50° or more and 80° or less, and may be 50° or more and 70° or less, or 60° or more and 70° or less. The hardness refers to type D durometer hardness, which is obtained by the measurement method specified in JIS K 6253-3.

[0040] The tensile strength (in accordance with ASTM D1708) of the ultra-high molecular weight PE resin composition that is the material of the sliding portion 8 is preferably 20 MPa or more at 25°C, and more preferably 30 MPa or more. In addition, the linear expansion coefficient of the ultra-high molecular weight PE resin composition is, for example, 30×10 －５ / °C or less, and may be 20×10 －５ / °C or less. Further, the aforementioned linear expansion coefficient is, for example, 10×10 －５ / °C or more. Note that the aforementioned linear expansion coefficient may be measured in the resin flow direction (MD direction) or in the direction perpendicular to the resin flow direction (CD direction). In addition, the aforementioned linear expansion coefficient is a value within the range of room temperature to 80°C.

[0041] The ultra-high molecular weight PE resin composition may be blended with a filler resistant to an alkaline aqueous solution having a pH of 7 to 11, for example, to improve friction and wear properties in cooling water. Examples of the filler include carbon fiber, graphite, PTFE resin, inorganic substances (mica, talc, calcium carbonate, etc.), and whiskers (calcium carbonate, potassium titanate, etc.). Among these fillers, it is preferable to use a non-fibrous filler, and in this case, it is more preferable not to contain a fibrous filler from the viewpoint of aggressiveness to a rotor that is a counterpart material. The non-fibrous filler may be any filler other than fibrous fillers having an aspect ratio such as carbon fiber, glass fiber, and whisker, and examples thereof include amorphous granular, spherical, scaly, and plate-like fillers. Among these, granular and spherical fillers having no anisotropy are preferable.

[0042] Well-known resin additives may also be blended into the ultra-high molecular weight PE resin composition to an extent that does not impair the effects of the present invention. Examples of such additives include friction property improvers such as boron nitride, molybdenum disulfide, and tungsten disulfide, and colorants such as carbon powder, iron oxide, and titanium oxide.

[0043] The main body portion 9 is formed from a rubber composition. The rubber composition is a composition containing a rubber component as a main component, and contains 50% by mass or more of the rubber component. The content of the rubber component may be 80% by mass or more, or 90% by mass or more.

[0044] As the rubber component, for example, synthetic rubbers such as ethylene propylene rubber (EPDM, EPM), acrylonitrile butadiene rubber (NBR), fluororubber, butadiene rubber, styrene butadiene rubber, styrene rubber, isoprene rubber, butyl rubber, nitrile rubber, chloroprene rubber, and silicone rubber are used. Examples of the fluororubber include vinylidene fluoride-based (FKM), tetrafluoroethylene-propylene-based (FEPM), and tetrafluoroethylene-perfluorovinyl ether-based (FFKM). These rubber components may be used alone, or two or more of them may be mixed and used.

[0045] Among the above rubber components, EPDM, EPM, or NBR are preferred from the viewpoint of low-temperature characteristics. Since seals for flow control valves are used in low-temperature environments below 0°C (for example, around -40°C) depending on the application, it is preferable that the elastic force does not decrease easily even in such low-temperature environments, and in this respect, EPDM is particularly preferred.

[0046] Furthermore, EPDM has -CH in its molecular structure. ２ -CH ２ - It contains ethylene units, which are common to the high molecular weight PE resin that constitutes the sliding part 8, resulting in excellent adhesion to the sliding part 8. Specifically, the two can be bonded together without using adhesive during molding, leading to improved productivity. For example, by vulcanizing the unvulcanized EPDM that forms the base of the main body 9 and the high molecular weight PE resin sheet that forms the base of the sliding part 8 while they are layered together, they can be integrated without the use of adhesive.

[0047] Furthermore, the above rubber composition may also contain well-known additives. For example, vulcanizing agents, vulcanization accelerators, reinforcing agents, anti-aging agents, softeners, colorants, etc., can be added.

[0048] The hardness of the main body 9 is, for example, 30° to 80°, may be 40° to less than 70°, or 40° to 60°. Furthermore, it is preferable that the hardness of the main body 9 is lower than the hardness of the sliding part 8. This allows the sliding part 8 to conform well to the surface shape of the mating member, improving friction and wear characteristics, as well as providing excellent sealing performance. In addition, since the entire sliding part 8 is supported by the more flexible main body 9, the sliding part 8 adheres well to the outer circumferential surface of the mating member, and even if the outer circumferential surface of the mating member is rough, the sliding part 8 can adhere closely to the outer circumferential surface over its entire circumference. Moreover, since the sliding part 8 is made of an ultra-high molecular weight PE resin composition with excellent roughness and wear characteristics, wear resistance can be ensured even when the outer circumferential surface of the mating member is rough (for example, surface roughness Ra 1.6 μm to Ra 3.2 μm) or when glass fibers or the like are exposed on the surface.

[0049] Furthermore, the absolute value of the hardness difference between the sliding part 8 and the main body 9 is preferably 30° or less, more preferably 20° or less, and may also be 10° or less. Reducing the absolute value of the hardness difference between the sliding part 8 and the main body 9 makes it easier to prevent the sliding part 8 from peeling off the main body 9.

[0050] The seal thickness (maximum axial length) of seal 7A is, for example, 3 mm to 15 mm, and preferably 3 mm to 8 mm. The seal thickness may be constant in the circumferential direction or may vary. The thickness ratio of the sliding portion 8 to the seal thickness is 0.5% to 10%. This thickness ratio allows the sliding portion to conform easily to the shape of the mating material.

[0051] The seal 7A can be manufactured, for example, as follows: A pre-formed ultra-high molecular weight PE resin sheet is placed in a seal-shaped mold. At this time, an adhesive is applied to the inner surface of the sheet as needed. Then, a molten rubber composition that forms the main body 9 is poured into the mold so as to cover the ultra-high molecular weight PE resin sheet. After the rubber composition has hardened, it is released from the mold to obtain a seal in which the sliding part 8 and the main body 9 are integrally formed. Alternatively, the use of adhesive may be omitted, and the sliding part 8 and the main body 9 may be joined by utilizing the crosslinking of the rubber composition.

[0052] The seal 7A has a sliding portion 8 and a main body portion 9, and is formed to be elastically deformable in the axial direction of the seal. Specifically, the seal 7A is elastically deformable by 1% or more in the axial direction relative to the maximum axial length of the seal, and more specifically, it is elastically deformable to the extent of the overlap ratio described later.

[0053] The overlap of the seal 7A is set as appropriate, but for example, it is pressed with an overlap of more than 3% but less than 35% in the axial direction relative to the maximum axial length of the seal. By keeping it within this range, it is easy to achieve both low torque and good sealing performance. As shown in Figure 2(c), in the seal 7A, the maximum axial length of the seal is h １is represented by, which refers to the axial length from the rear end surface 72 to the highest part of the protrusion 71b (the top with a substantially semicircular cross-section in the figure). The interference is calculated on the basis of this maximum axial length, as a ratio to the axial pressing amount (the deformation amount of the seal). The above-mentioned interference is preferably 5% or more and 25% or less in the axial direction relative to the maximum axial length of the seal, and more preferably 5% or more and 15% or less in the axial direction.

[0054] In the cross-sectional view of the seal 7A shown in FIG. 2(c), h ２ is the axial length from the rear end surface 72 to the highest part of the receding portion 71a (the top with a substantially semicircular cross-section in the figure).

[0055] The seal for a flow control valve of the present invention is not limited to the configurations shown in FIG. 1 and FIG. 2 above.

[0056] For example, in FIG. 1 and FIG. 2, a seal that is in sliding contact with the outer peripheral surface of a cylindrical rotor (mating member) is shown, but the seal may also be in sliding contact with the outer peripheral surface of a spherical mating member. In this case, for example, the seal may have a shape where the maximum axial length of the seal is constant in the circumferential direction. In addition, although cooling water is exemplified as the fluid in the above valve device, the fluid is not limited thereto.

[0057] Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

[0058] Examples 1 to 11, Comparative Examples 1 to 4 Seal test pieces in which a predetermined sliding portion and a main body portion are integrated were manufactured. The seal test piece has the shape shown in FIG. 2, with an inner diameter of φ20 mm, an outer diameter of φ25 mm, and a maximum axial length h １ of 7 mm, and h ２ of 5 mm.

[0059] For each seal test specimen, as shown in Tables 3 to 4 below, an ultra-high molecular weight PE resin sheet (hardness 65°) of a predetermined sheet thickness or a PTFE resin sheet of a predetermined sheet thickness was used for the sliding part. A predetermined rubber composition was used for the main body. In Examples 7 and 8 and Comparative Example 2, an adhesive was used to integrate the sliding part and the main body. In the other examples and Comparative Examples 3 and 4, vulcanization bonding was performed without using an adhesive to integrate the sliding part and the main body. The overlap was defined as the ratio of the axial indentation length to the maximum axial length (7 mm).

[0060] [Friction and Wear Test] A friction and wear test was conducted using the test apparatus 11 shown in Figure 3 with each seal test piece. The seal test piece 12 was mounted so as to protrude from the tip side of the cylindrical part 13, and the overlap was set with a spacer 14 to form a seal unit. The sliding part of the seal test piece 12 in this seal unit was set in a state where it was pressed against the outer surface of the cylindrical mating material 15. Then, the friction and wear test was performed by rotating the cylindrical mating material 15, and the dynamic friction coefficient and the amount of wear of the seal test piece 12 were measured. The dynamic friction coefficient was calculated from the average value over a test period of 100 hours. The amount of wear was calculated from the axial dimensional change of the seal test piece 12. Note that LLC (Long Life Coolant) in Table 1 is engine coolant for automobiles, and its main component is ethylene glycol.

[0061]

[0062] [Leak Test] A leak test was performed using each seal test piece with the leak testing machine 21 shown in Figure 4. The leak testing machine 21 comprises a housing 22, a cylindrical mating member 23, a seal test piece 27, and a spacer 24 for setting the interference fit. In the leak testing machine 21, the contact surface of the cylindrical mating member 23 with the seal test piece 27 is the curved shape of the mating member. Neither the seal test piece 27 nor the cylindrical mating member 23 rotates in the leak testing machine 21. The seal test piece 27 was assembled by inserting it into the inner circumferential surface of the cylinder from the end face of the cylindrical mating member 23 at the introduction part of the housing 22. At this time, the seal test piece 27 was pressed against the cylindrical mating member 23 using the spacer 24 to set a predetermined interference fit, and the sliding part 28 and the surface of the cylindrical mating member 23 were brought into contact. The leak testing machine 21 was assembled by closing the housing 22 with a lid that has an LLC inlet passage.

[0063] In the leak test machine 21, LLC was introduced through the inlet passage 25 to reach a predetermined pressure and passed through the seal opening of the seal test piece 27. The LLC that passed through then passed inside the cylindrical mating member 23, flowed out through the outlet passage 26, circulated, and then reintroduced. During this process, the LLC leaked from the sliding part 28 of the seal test piece 27 was collected using a graduated cylinder from the metering unit 29, and the leak rate (mL / min) was measured. The leak rate was calculated as the average value of 3 tests (n=3). The test conditions for the leak test are shown in Table 2 below.

[0064]

[0065] The results of each of the above tests, along with the configuration of the seal test specimens, are shown in Tables 3 and 4 below.

[0066]

[0067]

[0068] First, regarding the results of the friction and wear tests, in Examples 1 to 11, where an ultra-high molecular weight PE resin sheet was used in the sliding part, a low coefficient of dynamic friction was maintained against the mating material made of glass fiber-reinforced PPS resin, and the amount of wear was small, less than 0.05 mm. On the other hand, in Comparative Example 1, where no sheet was used in the sliding part and the main body was made of EPDM rubber (hardness 60°), the coefficient of dynamic friction was very high, and the amount of wear was also large. In Comparative Example 2, where a PTFE resin sheet was used in the sliding part, the coefficient of dynamic friction was kept low, but the wear resistance of the sheet was low, and the amount of wear was large. Furthermore, in Comparative Example 4, where the overlap was set to 35%, which is larger than the predetermined value, the pressing force was strong, and the amount of wear increased.

[0069] Next, regarding the leak test results, in Examples 1 to 11, the leak rate was 10 mL / min or less. In the range of 5% to 25% of the overlap, there was a tendency for the leak rate to decrease as the overlap increased (Examples 1 to 3). Furthermore, regarding the hardness of the main body, the leak rate increased slightly when the hardness decreased to a certain extent (Examples 9 to 10). In Example 11, where EPDM with a harder hardness than the sliding part was used for the main body, both the leak rate and the coefficient of dynamic friction increased slightly.

[0070] As shown in Examples 1 to 11, a sliding part made of an ultra-high molecular weight PE resin composition and a main body made of a rubber composition are integrated, and by creating a flow control valve seal with a predetermined tightening allowance, it was possible to achieve both low torque and good sealing performance.

[0071] The seal for flow control valves of the present invention combines low torque and good sealing performance, and therefore can be widely used as a seal for flow control valves.

[0072] 1 Valve device (flow control valve device) 2 Housing 2a Inner surface 3 Inlet section 4A, 4B, 4C Discharge section 5 Rotating shaft 6 Rotor 6a Outer surface 6b Rotor opening 7A, 7B, 7C Seal (seal for flow control valve) 71 Front surface 71a Retracted section 71b Protruding section 72 Rear end surface 73 Inner surface 74 Outer surface 8 Sliding part 9 Main body 11 Test machine 12 Seal test piece 13 Cylindrical part 14 Spacer 15 Cylindrical mating material 21 Leak test machine 22 Housing 23 Cylindrical mating member 24 Spacer 25 Inlet passage 26 Outlet passage 27 Seal test piece 28 Sliding part 29 Metering section

Claims

1. A flow control valve seal that slides against a mating member with an overlap, comprising a sliding portion that slides against the mating member and a main body portion that presses the sliding portion against the mating member, wherein the sliding portion and the main body portion are integrally molded, the sliding portion is made of an ultra-high molecular weight polyethylene resin composition, the main body portion is made of a rubber composition, and the seal has an overlap of 5% to 25% in the axial direction relative to the maximum axial length of the flow control valve seal with respect to the mating member.

2. The seal for a flow control valve according to claim 1, characterized in that the sliding portion is in the form of a sheet with a thickness of 0.05 mm or more and 0.3 mm or less.

3. The seal for a flow control valve according to claim 1, characterized in that the main body is made of ethylene propylene rubber and is integrated with the sliding part without the use of an adhesive.

4. The seal for a flow control valve according to claim 1, characterized in that the hardness of the main body is 40° or more and less than 70°.

5. The seal for a flow control valve according to claim 4, characterized in that the hardness of the main body is less than the hardness of the sliding part, and the difference in their hardness is within 20°.

6. The seal for a flow control valve according to claim 1, characterized in that the sliding portion is in the form of a sheet with a thickness of 0.05 mm or more and 0.3 mm or less, the main body is made of ethylene propylene rubber and is integrated with the sliding portion without the use of an adhesive, and the hardness of the main body is 40° or more and less than 70°.

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