Seal for flow rate control valve

Abstract

To provide a seal for a flow rate control valve capable of improving assemblability while maintaining sealability equivalent to a conventional product additionally using a seal ring in a flow rate control valve device.SOLUTION: A seal 7B is a seal for a flow rate control valve used in a flow rate control valve device, which is attached to an inner peripheral surface of an introducing part or a discharge part in a housing and is brought into sliding contact with an outer peripheral surface of a rotor. A protrusion 8, which is engaged with the inner peripheral surface of the introducing part or the discharge part and seals a gap between an outer peripheral surface 7d and an inner peripheral surface 2a of the seal 7B, is integrally disposed on the outer peripheral surface 7d by using the same material as a seal body, and is made with a synthetic resin whose bending elastic modulus is 400-1200 MPa.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a seal for a flow control valve used in a flow control valve device that adjusts the flow rate and flow path of a fluid. [Background technology]

[0002] Conventionally, automobiles are provided with a circulation flow path for circulating coolant to cool the engine, but as automobiles become more electric, heat management is becoming more important, and there is a growing trend to use coolant not only for the engine but also for cooling the motor, etc. The circulation flow path for coolant has multiple flow paths, and within these circulation paths, flow control valve devices are arranged to control the flow rate of the coolant, and these valve devices adjust the flow rate of the coolant in each flow path.

[0003] As a flow control valve device, for example, Patent Document 1 discloses a device including a rotor, a seal member (seal for a flow control valve) that makes sliding contact with the outer peripheral surface of the rotor, a biasing member that presses the seal member, and a drive mechanism that rotates the rotor. Patent Document 1 discloses a seal member in which the abutment surface at the tip that makes sliding contact with the outer peripheral surface of the rotor is formed as an arc-shaped curved surface that follows the cylindrical outer peripheral surface of the rotor, and further, at least the front end or rear end of the arc-shaped curved surface that forms the abutment surface when viewed in the direction of rotation of the rotor, a non-contact portion that does not make contact with the outer peripheral surface of the rotor is formed as a ridge portion.

[0004] Patent Document 2 discloses a flow control valve device including a housing having an inlet for receiving cooling water and an outlet for discharging cooling water, a resin rotor provided inside the housing and having a spherical or cylindrical outer circumferential surface that rotates relative to the housing, and an annular flow control valve seal provided inside the housing between the rotor and the inlet or outlet and in sliding contact with the outer circumferential surface of the rotor. Patent Document 2 discloses that the flow control valve seal is an injection-molded article made of a resin composition having an injection-moldable fluororesin as the base resin, and that the fluororesin is at least one resin selected from tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) resin, tetrafluoroethylene-hexafluoropropylene copolymer (FEP) resin, and tetrafluoroethylene-ethylene copolymer (ETFE) resin. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-179122 A [Patent Document 2] Japanese Patent Application Publication No. 2020-106149 Summary of the Invention [Problem to be solved by the invention]

[0006] In the flow control valve devices described in Patent Documents 1 and 2, a flow control valve seal is attached to the inner circumferential surface of the flow path of the housing. A seal ring mounting groove is formed on the outer circumferential surface of the flow control valve seal, and a seal ring is housed in this groove to seal the gap between the flow control valve seal and the housing. For example, Patent Document 1 uses an X-ring as the seal ring, while Patent Document 2 uses an O-ring.

[0007] As described above, conventional flow control valve devices use a seal ring to seal the gap between the flow control valve seal and the housing. This increases the number of parts and assembly steps, resulting in higher costs. Furthermore, during assembly, the seal ring interferes with the inlet and inner peripheral surface of the housing, making assembly defects such as twisting and detachment more likely to occur. If assembly is poor, even if the seal ring is housed in the seal groove, the rotor and the sealing surface of the flow control valve seal will not make proper contact, which could result in fluid leakage from the gap.

[0008] The present invention has been made in view of the above circumstances, and aims to provide a seal for a flow control valve that can improve assembly ease while maintaining sealing performance equivalent to that of conventional products that use a separate seal ring in a flow control valve device. [Means for solving the problem]

[0009] The seal for a flow control valve of the present invention (hereinafter also simply referred to as "seal") is used in a flow control valve device comprising a housing having an inlet and outlet for a fluid, and a rotor provided inside the housing, having a spherical or cylindrical outer peripheral surface, and rotating relative to the housing, and is attached to the inner peripheral surface of the inlet or outlet within the housing and comes into sliding contact with the outer peripheral surface of the rotor, and is characterized in that a convex portion is provided integrally with the seal body on the outer peripheral surface of the seal, which is fitted into the inner peripheral surface of the inlet or outlet and seals the gap between the outer peripheral surface of the seal and the inner peripheral surface, and the seal is formed from a synthetic resin having a flexural modulus of elasticity of 400 MPa to 1200 MPa.

[0010] The material is made of a resin composition containing at least one resin selected from PFA resin, FEP resin, and ETFE resin as a base resin, and is characterized by having a flexural modulus of elasticity of 400 MPa to 950 MPa.

[0011] The convex portion is a single annular convex portion extending in the circumferential direction, and is characterized in that its cross section is arc-shaped.

[0012] The protruding height of the annular convex portion is characterized by being 3% to 10% of the radial thickness of the seal.

[0013] The seal is cylindrical, and one axial end face (sealing face) that comes into sliding contact with the outer peripheral surface of the rotor is formed as an arc-shaped curved surface that follows the outer peripheral surface of the rotor. [Effects of the Invention]

[0014] The seal for a flow control valve of the present invention is attached to the inner peripheral surface of an inlet or outlet port within a housing and comes into sliding contact with the outer peripheral surface of a rotor, and a protrusion that fits onto the inner peripheral surface of the inlet or outlet port and seals the gap between the outer peripheral surface and the inner peripheral surface of the seal is made of the same material as the seal body and is formed integrally therewith, thereby improving assembly into the housing while maintaining sealing performance equivalent to conventional products, and further improving assembly of the seal because the seal is formed from a synthetic resin with a flexural modulus of 400 MPa to 1200 MPa, which provides appropriate elasticity and leads to further improvement in assembly of the seal. Note that Patent Document 2 does not consider the relationship between the flexural modulus and sealing performance or the assembly ability of a seal for a flow control valve.

[0015] Furthermore, since the convex portion of the seal is made of the same material as the seal body, it can be produced simultaneously with the seal body, which reduces the number of processing steps and costs.

[0016] The above material is made of a resin composition whose base resin is at least one resin selected from PFA resin, FEP resin, and ETFE resin, and has a flexural modulus of 400 MPa to 950 MPa, which makes it easy to improve adhesion to the outer surface of the rotor and to the inner surface of the housing, and further improves sealing properties and assembly ease.

[0017] The convex portion is a single annular convex portion extending in the circumferential direction and has an arc-shaped cross section, which makes it easy to prevent snagging during assembly and makes it possible to preferably prevent assembly defects. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic cross-sectional view showing an example of a flow control valve device equipped with a seal for a flow control valve of the present invention. [Figure 2] 1A and 1B are axial cross-sectional views showing an example of a seal for a flow control valve according to the present invention. [Figure 3] FIG. 2 is an axial cross-sectional view of a seal for a flow control valve used in the examples. [Figure 4] FIG. 1 is a schematic diagram of a leak tester. DETAILED DESCRIPTION OF THE INVENTION

[0019] An example of a flow control valve device (hereinafter simply referred to as a "valve device") employing the flow control valve seal of the present invention will be described with reference to Fig. 1. As shown in Fig. 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 in sliding contact with the outer peripheral surface 6a of the rotor 6. The rotating shaft 5 is connected to a motor (not shown). Note that the protrusions formed on the seals 7A, 7B, and 7C are not shown in Fig. 1, and details will be described in Fig. 2.

[0020] Housing 2 has inlet 3 that receives cooling water from an engine or the like, and outlets 4A, 4B, and 4C that send the cooling water to various devices such as a radiator. In Fig. 1, valve device 1 has a three-way flow path for sending the fluid, and is provided with three cylindrical outlets. In valve device 1, seals 7A, 7B, and 7C are attached to the inner circumferential surface 2a of each of outlets 4A, 4B, and 4C, respectively.

[0021] In the valve device 1, no seal is attached to the inner circumferential surface of the introduction portion 3, but a seal may be attached to the introduction portion in addition to the discharge portion.

[0022] The rotor 6 is a rotating rotor with a hollow interior, and its outer peripheral surface 6a, which slides against the seals 7A, 7B, and 7C, is cylindrical. The rotor 6 has a rotor opening 6b penetrating the interior and exterior, and the seals 7A, 7B, and 7C each have a seal opening penetrating through their center. As the rotating shaft 5 rotates in the direction of the arrow, the rotor 6 also rotates. This rotation opens the rotor opening 6b and the seal openings, resulting in an open valve state, and closes the rotor opening 6b and the seal openings, resulting in a closed valve state. In the open valve state shown in Figure 1, cooling water introduced through the inlet 3 of the housing 2 is supplied from the rotor 6 to cooling components such as a battery through the outlets 4A, 4B, and 4C. Rotating the rotor 6 thus controls the opening and closing of the valve device 1, thereby adjusting the flow rate and distribution of cooling water.

[0023] The rotor 6 is not particularly limited in material, but may be made of resin, for example, and more specifically, may be an injection-molded body 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, such as polyphenylene sulfide (PPS) resin, polyamide (PA) 66 resin, semi-aromatic PA resin, or polyether ether ketone (PEEK) resin. As semi-aromatic PA resins, PA9T resin and PA10T resin, which have low water absorption, 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.

[0024] Furthermore, it is preferable to blend glass fiber into the resin composition used for the rotor 6 in order to obtain high strength, high elasticity, and high dimensional accuracy. PPS resin blended with glass fiber is more preferable because it has excellent high strength and high elasticity. When blending glass fiber, the blending amount is 10% by mass to 50% by mass, preferably 20% by mass to 40% by mass, based on the total resin composition. If the glass fiber content is greater than the predetermined amount, the seal is more likely to be worn and damaged, while if it is less, it becomes difficult to obtain sufficient strength. Furthermore, this resin composition may contain a combination of glass fiber and a non-fibrous filler in order to eliminate anisotropy in molding shrinkage and improve dimensional accuracy.

[0025] In the housing 2, the inner circumferential surfaces 2a of the discharge portions 4A, 4B, and 4C are made of, for example, resin, and more specifically, are formed from a molded body of a resin composition with a thermoplastic resin as the base resin. The thermoplastic resin is not particularly limited, but examples thereof include PPS resin, PA66 resin, semi-aromatic PA resin, and PEEK resin. Among these resins, PA66 resin is preferred because it has excellent alkali resistance and is inexpensive.

[0026] 1, seal 7A is fitted onto inner circumferential surface 2a of discharge portion 4A, with seal surface 7a in sliding contact with outer circumferential surface 6a of rotor 6. When a seal ring such as an O-ring is used to fit the seal, it is prone to twisting or falling off during assembly due to interference with the inlet of the inner circumferential surface of the discharge portion or friction with the inner circumferential surface. However, as will be described later, the seal of the present invention has a convex portion that also serves as a fitting portion, which is formed integrally with the seal body, and therefore can be properly assembled without twisting or falling off of the seal ring.

[0027] The seal 7A may be attached by being pressed against the rotor 6 via a spring (see, for example, FIG. 4). Utilizing the biasing force of the spring improves the adhesion between the seal surface 7a and the outer peripheral surface 6a of the rotor 6, making it easier to maintain low leakage. Specifically, in the discharge portion 4A, the end face of the seal 7A opposite to the seal surface 7a can be pressed by a coil spring or the like.

[0028] Next, the seal for a flow control valve of the present invention will be described with reference to Fig. 2. In the present invention, the direction along the central axis O of the seal is referred to as the axial direction, the direction perpendicular to the central axis O in a plan view seen from the axial direction is referred to as the radial direction, and the direction circumferentially around the central axis O in the plan view is referred to as the circumferential direction. Note that Fig. 2 uses seal 7B for the description, but the same applies to seals 7A and 7C.

[0029] FIG. 2(a) is an axial cross-sectional view of the seal before it is attached to the housing. As shown in FIG. 2(a), the seal 7B is a cylindrical member having a seal opening penetrating through its central shaft. One axial end face forms the seal surface 7a. The seal surface 7a is the surface that abuts against the outer circumferential surface of the rotor, and in FIG. 2(a), the entire seal surface 7a is formed as an arc-shaped curved surface that conforms to the outer circumferential surface of the rotor. This makes it easier for the entire seal surface 7a to adhere closely to the outer circumferential surface of the rotor. The seal surface 7a may also be flat.

[0030] The other axial end face 7b of the seal 7B is formed as a flat surface perpendicular to the axial direction. This end face 7b is in contact with, for example, the above-mentioned spring, and serves to determine the axial position of the seal 7B, for example.

[0031] The inner peripheral surface 7c of the seal 7B is formed as a straight cylindrical inner surface parallel to the axial direction. The inner peripheral surface 7c has no protrusions or recesses, so it does not obstruct the flow of fluid.

[0032] The outer peripheral surface 7d of the seal 7B is formed with a straight cylindrical outer surface 7e parallel to the axial direction and a protrusion 8 protruding radially outward. In FIG. 2, the protrusion 8 is a single annular protrusion extending continuously along the circumferential direction. The protrusion 8 is formed integrally with the seal body using the same material. Note that the seal body here refers to the portion of the seal 7B other than the protrusion 8.

[0033] As shown in Figure 2(b) (enlarged view of part A when assembled), protrusion 8 fits into inner peripheral surface 2a of housing 2 and seals the gap between outer peripheral surface 7d of seal 7B and inner peripheral surface 2a. In conventional products, a seal ring such as an O-ring is housed in a seal ring mounting groove to seal the gap with the housing, but seal 7B seals the gap by fitting with protrusion 8 that is provided integrally with the seal. This reduces the number of parts in the valve device and the assembly man-hours.

[0034] The protruding height h of the protrusion 8 (the radial length from the cylindrical outer surface 7e to the apex of the protrusion 8) may be any height that can seal the gap between the outer peripheral surface 7d of the seal 7B and the inner peripheral surface 2a of the housing 2, and specifically is about 0.1 to 0.2 mm. The protrusion 8 also functions as a fitting portion for the housing 2, and the protruding height h of the protrusion 8 also includes an interference. The protruding height h satisfies the relationship φ3 > φ1 > φ2, where φ1 is the inner diameter of the inner peripheral surface 2a at the discharge portion or the like of the housing 2 where the seal 7B is to be attached, φ2 is the outer diameter of the cylindrical outer surface 7e of the seal 7B before attachment, and φ3 is the outer diameter of the apex of the protrusion 8 of the seal 7B before attachment.

[0035] Furthermore, the protruding height h of the convex portion 8 is, for example, 3% to 10%, or may be 3% to 6%, of the radial thickness T of the seal 7B. The radial thickness T of the seal 7B is the thickness of the portion excluding the convex portion 8, and in FIG. 2(a) is the thickness between the inner and outer surfaces of the straight cylinder.

[0036] In the seal 7B, the axial position of the protrusion 8 is not particularly limited.

[0037] 2, the cross-sectional shape of the protrusion 8 may be a trapezoid, a triangle, or the like as long as it is a shape that can prevent it from getting caught when it is assembled to the inner circumferential surface 2a of the housing 2. Furthermore, it is not limited to a bilaterally symmetrical shape, and it may also be an asymmetrical shape.

[0038] 2 shows the configuration of the protrusion 8 as a single annular protrusion extending in the circumferential direction, but the configuration is not limited to this as long as the protrusion can be fitted into the inner peripheral surface 2a of the housing 2 and seal the gap with the housing 2. For example, the protrusion may be formed so as to extend continuously in an elliptical shape while being offset in the axial direction, or multiple protrusions spaced apart in the axial direction may be formed. For example, when multiple protrusions are formed, the protrusion heights may be different between the protrusions.

[0039] Furthermore, in the present invention, taking into consideration ease of assembly to the inner peripheral surface 2a of the housing 2 and sealing performance, the seal 7B is formed from a material with a flexural modulus of 400 MPa to 1200 MPa. By setting the flexural modulus of the seal 7B within this range, appropriate elasticity can be exerted, preventing galling of protrusions during assembly. This also contributes to improved adhesion between the rotor and the inner peripheral surface of the housing. The flexural modulus is preferably 400 MPa to 950 MPa, and more preferably 400 MPa to 700 MPa. The flexural modulus is measured by a method in accordance with ASTM D790.

[0040] The material of the seal of the present invention is not particularly limited as long as its flexural modulus satisfies the above range. The seal is a molded article of a resin composition, such as polyacetal or fluororesin. Among these, it is preferable to use a fluororesin as the base resin of the resin composition, since it is easy to keep the flexural modulus within the above range and facilitates smooth assembly. Furthermore, a molded article using a fluororesin as the base resin has low elasticity and low hardness, so it easily deforms along the curved (spherical or cylindrical) outer peripheral surface of, for example, a resin rotor, and has excellent adhesion to the rotor. Furthermore, fluororesin has excellent alkali resistance and low water absorption, and can suppress resin deterioration even in environments where it comes into contact with, for example, cooling water.

[0041] Examples of fluororesins that can be used include PFA resin, FEP resin, ETFE resin, polytetrafluoroethylene (PTFE) resin, etc. These may be used alone or in combination.

[0042] The molecular structure of PTFE resin is represented by -(CF2-CF2)n- (n is an integer), and molding powder produced by suspension polymerization or fine powder produced by emulsion polymerization can be used. Molding powder produced by suspension polymerization has a higher molecular weight than fine powder produced by emulsion polymerization and is preferable in terms of abrasion resistance. Modified PTFE resins, in which perfluoroalkyl ether groups (-CpF2p-O-) (p is an integer of 1-4) or polyfluoroalkyl groups (H(CF2)q-) (q is an integer of 1-20) are introduced into standard PTFE, can also be used as the PTFE resin.

[0043] The method for forming the seal is not particularly limited, and injection molding, extrusion molding, compression molding, etc. can be used. In the case of extrusion molding or compression molding, a rod or pipe material is formed and then machined into the seal shape. Injection molding is preferred from the viewpoint of low cost production.

[0044] When molding a resin composition based on PFA resin, FEP resin, or ETFE resin, for example, the raw materials can be dry-mixed using a Henschel mixer, a ball mixer, a ribbon blender, a Lödige mixer, or the like, and then melt-kneaded using a melt extruder such as a twin-screw extruder to obtain molding pellets, which can then be molded by injection molding.

[0045] To reduce the flexural modulus of the resin composition, an elastomer may be blended into the fluororesin. Fluororubber is a suitable elastomer. The type of fluororubber is not limited, but vinylidene fluoride (FKM), tetrafluoroethylene-propylene (FEPM), and tetrafluoroethylene-perfluorovinyl ether (FFKM) can be used. The FKM may be either a binary or ternary system.

[0046] Furthermore, in order to improve friction and wear characteristics in cooling water, for example, it is preferable to blend a filler that is resistant to an alkaline aqueous solution of pH 7 to 11 into the resin composition. Examples of fillers 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 to not include a fibrous filler in view of the attacking potential of the rotor, which is the mating material.

[0047] The non-fibrous filler may be any filler other than a fibrous filler having an aspect ratio such as carbon fiber, glass fiber, whisker, etc., and examples thereof include irregular granular, spherical, scale-like, plate-like fillers, etc. Among these, non-anisotropic granular and spherical fillers are preferred.

[0048] Graphite is preferably used as the non-fibrous filler. Graphite has the effect of imparting low friction and low wear characteristics in cooling water. While flake, granular, or spherical graphite can be used, granular or spherical graphite is more preferred, as it does not increase the elastic modulus of the resin composition. The average particle size of graphite is not limited, but is preferably 3 μm to 50 μm, more preferably 10 μm to 30 μm. If it exceeds 50 μm, the tensile elongation characteristics of the resin composition will deteriorate. The average particle size can be measured, for example, using a particle size distribution measuring device that utilizes laser light scattering. A seal made of a resin composition in which graphite is blended with the above-mentioned base resin is less susceptible to wear and damage to, for example, a resin rotor, and provides stable sealing performance over a long period of time. Furthermore, its excellent alkali resistance allows for long-term use without deterioration.

[0049] Furthermore, when a fused fluororesin such as PFA resin, FEP resin, or ETFE resin is used as the base resin of the resin composition, a PTFE resin may be blended as a filler. The average particle size of the PTFE resin is not particularly limited, but is preferably 10 μm to 50 μm.

[0050] Well-known resin additives may be added to the resin composition to the extent that the effects of the present invention are not impaired. 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.

[0051] The resin composition used in the seal of the present invention contains 70 to 100% by volume of the above-mentioned base resin relative to the entire resin composition. When a filler is blended into the resin composition, a composition in which the filler is 3 to 30% by volume and the remainder is the base resin is preferred, and a composition in which the filler is 5 to 20% by volume and the remainder is a fluororesin is more preferred. If the filler exceeds 30% by volume, the tensile elongation properties of the resin composition may be reduced.

[0052] In the flow control valve device of the present invention, it is preferable that the seal for the flow control valve is a molded article of a fluororesin composition, and the rotor is a molded article of a resin composition made of a base resin different from that of the seal. In this case, since the seal and the rotor are made of different resin materials, the increase in wear due to a high friction coefficient that would be expected when materials made of the same resin slide against each other can be prevented, and good low friction and low wear can be easily achieved.

[0053] The seal for a flow control valve of the present invention is not limited to the configurations shown in Figures 1 and 2. In the above valve device, cooling water is used as an example of the fluid, but the fluid is not limited to this. [Example]

[0054] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to the following examples.

[0055] Examples 1 to 3, Comparative Example 1 Bending test pieces and seal test pieces with the cross-sectional shape shown in Figure 3(a) were prepared by injection molding using resin compositions containing each base resin shown in Table 1. The seal test pieces had a radial thickness T of 3 mm and a protruding height h of 0.16 mm.

[0056] Reference examples 1~2 A seal test piece having the cross-sectional shape shown in Fig. 3(b) was produced by injection molding using the same resin composition as in Example 2. As shown in Fig. 3(b), this seal test piece had a rectangular seal ring mounting groove formed in it, and in Reference Example 1 a rubber O-ring was placed in this seal ring mounting groove, while in Reference Example 2 a rubber X-ring was placed in it.

[0057] Using the obtained bending test pieces, a test was carried out in accordance with ASTM D790 to measure the flexural modulus (unit: MPa) at 25° C. The results are shown in Table 1. The materials of Examples 1 to 3 had a flexural modulus of less than 1000 MPa.

[0058] [Table 1]

[0059] [Leak test] A leak test was conducted using each seal test piece using a leak tester. A schematic diagram of the leak tester is shown in Figure 4. As shown in Figure 4, the tester 11 includes a housing 12, a cylindrical mating member 13, a seal test piece 17, and a coil spring 14. In the tester 11, the cylindrical mating member 13 does not rotate but simulates the rotor of a valve device. The seal test piece 17 was inserted into the cylindrical inner surface of the insertion section of the housing 12 and assembled. The seal test piece 17 was pressed against the cylindrical mating member 13 by the spring load of the coil spring 14, bringing the seal surface 17a into contact with the cylindrical mating member 13. The tester 11 was then assembled by closing the housing 12 from the side opposite the seal of the coil spring with a lid equipped with an LLC (Long Life Coolant) inlet.

[0060] 4 shows seal test pieces of Examples 1 to 3 and Comparative Example 1, each having a protrusion 18 formed on the outer circumferential surface, as seal test piece 17. Note that in the seal test pieces of Reference Examples 1 and 2, each seal ring was housed in its seal ring mounting groove and assembled.

[0061] In the testing machine 11, LLC was introduced into the inlet channel 15 to a predetermined pressure and passed through the seal opening of the seal test piece 17. The LLC that passed through flowed out through the outlet channel 16, circulated, and then flowed in again. During this process, LLC that leaked from the seal surface 17a and outer peripheral surface 17b of the seal test piece 17 was collected in a measuring cylinder from the measuring section 19, and the leakage rate (mL / min) was measured. The leakage rate was calculated as the average value of three tests (n=3). The test conditions for the leak test are shown in Table 2 below, and the test results are shown in Table 3 below.

[0062] [Table 2]

[0063] [Table 3]

[0064] As shown in Table 3, Examples 1 to 3 had the same leakage amount as the conventional products, Reference Examples 1 and 2. On the other hand, in Comparative Example 1, the rigidity of the seal test piece was high, and when the seal test piece was assembled into the housing, galling occurred on the protruding portion, making assembly impossible.

[0065] [Assembly test] An assembly test was conducted using each seal test piece. This test consisted of inserting and removing 30 seals one by one into the leak tester 11 shown in Figure 4. The assembly was evaluated (presence or absence of galling, etc.). The results are also shown in Table 3 above.

[0066] As shown in Table 3, Examples 1 to 3 could be assembled without any problems, and no galling occurred on the protruding portions. Although no specific evaluation was performed, Examples 1 to 3, which are conventional products, have an integrated protruding portion. Since no separate seal ring is used, Examples 1 to 3 did not twist or fall off the seal ring, and assembly was smooth. On the other hand, in Comparative Example 1, galling occurred on the protruding portions of all 30 seal test pieces, resulting in assembly failure. [Industrial Applicability]

[0067] The seal for a flow control valve of the present invention can improve assembly in a flow control valve device while maintaining the same sealing performance as conventional products that use a separate seal ring, and therefore can be widely used as a seal for a flow control valve. [Explanation of symbols]

[0068] 1. Valve device (flow control valve device) 2. Housing 2a Inner surface 3 Introduction 4A, 4B, 4C Discharge part 5 Rotation Axis 6 rotors 6a Outer surface 6b Rotor opening 7A, 7B, 7C Seals (Flow Control Valve Seals) 7a sealing surface 7b End face 7c Inner surface 7d Outer surface 7e Cylindrical outer surface 8 Convex part 11 Testing Machine 12 Housing 13 Cylindrical mating member 14 Coil spring 15 Inflow channel 16 Outflow channel 17 Seal test specimen 18 Convex part 19 Measuring section

Claims

1. The present invention is used in a flow control valve device including a housing having an inlet and an outlet for a fluid, and a rotor provided inside the housing, having a spherical or cylindrical outer circumferential surface, and rotating relative to the housing, a seal for a flow control valve that is attached to an inner circumferential surface of the inlet portion or the outlet portion in the housing and that is in sliding contact with an outer circumferential surface of the rotor, a protrusion that fits into an inner peripheral surface of the inlet or outlet portion and seals a gap between the outer peripheral surface of the flow control valve seal and the inner peripheral surface is provided integrally with the seal body and made of the same material; The seal for a flow control valve is formed from a synthetic resin having a flexural modulus of elasticity of 400 MPa to 1200 MPa.

2. The seal for a flow control valve according to claim 1, characterized in that the material is made of a resin composition having at least one resin selected from the group consisting of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin, tetrafluoroethylene-hexafluoropropylene copolymer resin, and tetrafluoroethylene-ethylene copolymer resin as a base resin, and has a flexural modulus of elasticity of 400 MPa to 950 MPa.

3. 3. The seal for a flow control valve according to claim 1, wherein the protrusion is a single annular protrusion extending in the circumferential direction and has an arc-shaped cross section.

4. 4. The seal for a flow control valve according to claim 3, wherein the protruding height of the annular convex portion is 3% to 10% of the radial thickness of the seal for a flow control valve.

5. 3. The seal for a flow control valve according to claim 1 or 2, characterized in that the seal for a flow control valve is cylindrical, and one axial end face that comes into sliding contact with the outer peripheral surface of the rotor is formed as an arc-shaped curved surface that follows the outer peripheral surface of the rotor.

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