MANUFACTURING METHOD FOR A VALVE DEVICE

Abstract

A manufacturing process for a valve device (90) comprising the following: a housing (91) containing a channel (80) in which a fluid flows; a valve (70, 77, 78) provided in the channel (80) and configured to open or close the channel (80) by rotational displacement; a shaft (95) configured to rotate integrally with the valve (70, 77, 78); a sealing ring (301 to 305) made of a resin and configured to seal a gap between an inner wall (84) of a channel element (81) forming the channel (80) and the valve (70, 77, 78) when the valve (70, 77, 78) is fully closed; and a spring (50) made of a metal, arranged in a ring shape in an area within a width of the sealing ring (301 to 305) in a radial direction and configured to push the sealing ring (301 to 305) outwards or inwards in a radial direction with respect to a sealing counterpart; the manufacturing process comprises the following steps: Assembling in a first assembly process (S1) the components of the valve device (90), which includes the valve, the sealing ring (301 to 305) and the spring (50); Heating the sealing ring (301 to 305) in a heat treatment process (S3) to a predetermined treatment temperature in a condition in which the spring (50) is installed in the sealing ring (301 to 305) and the sealing ring (301 to 305) is arranged between the valve (70, 77, 78) and the inner wall (84) of the channel (80) to cause the sealing ring (301 to 305) to deform plastically due to the tension of the spring (50) so that the sealing ring (301 to 305) follows a shape of the sealing counterpart; and Assembling in a second assembly process (S4) different components of the valve device (90) than the components assembled in the first assembly process (S1).

Description

CROSS-REFERENCE TO A RELATED APPLICATION

[0001] This application claims priority to Japanese Patent Application No. 2017-159190, filed on August 22, 2017. The entire disclosure of the above-referenced application is incorporated herein by reference.

[0002] US 4 165 859 A discloses a bidirectional valve seal assembly comprising a retaining ring secured to the valve body, the retaining ring and the valve body each having a recess to define a chamber therebetween, and a seat ring having a base and a pair of diverging legs compressively disposed in the chamber.

[0003] DE 30 24 589 A1 discloses a butterfly valve with a sealing ring which is U-shaped in cross-section and which is clamped with its radially inwardly directed U-profile legs on the valve disc edge by a retaining ring and a support ring inserted between the U-profile legs and is made of a plastic which is resistant to high temperatures, preferably polytetrafluoroethylene, wherein the sealing ring with its U-profile base comes into sealing contact with the housing and carries a metallic helical spring ring inserted between the U-profile base and the support ring, wherein a) the U-profile leg (22) of the sealing ring (12) resting against the valve disc (3) is firmly clamped between the valve disc and the support ring (19) by the retaining ring (14) and the other U-profile leg (23) has a limited play towards the retaining ring (14) allowing movement of this leg, b) the end of the movable U-profile leg (23) carries a nose (24) which engages in a form-fitting manner in a groove (25) of the retaining ring (14) provided with play, c) a spring (17) wound from a flat strip, with a circular winding cross-section, is provided as the helical spring ring, the cylinder jacket of which is formed by the broad side of the flat strip, d) the support ring (19) is provided with an inwardly curved support surface (2o) for the flat band spring (17), which, together with the inner contour of the U-shaped sealing ring (12), forms a free space (21) which is oval in cross-section and envelops the flat band spring (17), the oval extension of which runs approximately parallel to the conical housing seat surface (16) which widens towards the side of the firmly clamped U-profile leg (22). TECHNICAL FIELD

[0004] The present disclosure relates to a manufacturing method for a valve device. BACKGROUND

[0005] A known butterfly-type valve device or a valve device with a throttle valve is used to open or close a passage in which gas or the like flows in an exhaust gas recirculation (EGR), and the device includes a sealing ring for sealing a clearance between a valve and an inner wall of a passage part.

[0006] In the valve device, the ambient temperature of a gas passage ranges widely, from a low temperature in a state where the gas passage is kept in a cold area to a high temperature in a state where the gas passage is exposed to exhaust gas. Furthermore, the materials of the valve, the sealing ring, and a nozzle installed in the gas passage are different, and the differences in linear expansion of the materials are taken into account to determine a clearance.

[0007] For example, Patent Document 1 discloses a valve device that includes a resin seal ring instead of a metal seal ring that was generally used before that time. When a valve is fully closed, the diameter of the resin seal ring is increased by elastic deformation, an outer peripheral surface of the seal ring abuts against an inner wall of a passage portion, and a clearance is sealed. (Patent Document 1) JP 2016-211678 A

[0008] In a mass production process, variations in the outer diameter and roundness of the seal ring, as well as the inner diameter and roundness of a channel, occur. These variations result in clearance after assembly or assembly of the components, and sealing performance may be insufficient when the valve is fully closed. SUMMARY OF THE INVENTION

[0009] An object of the present disclosure is to provide a manufacturing method for a valve device configured to ensure the sealing performance when the valve is fully closed regardless of variations in the dimensions and roundness of the components.

[0010] A manufacturing method for a valve device comprising a housing, a valve, a stem, a resin seal ring, and a metal spring is described in the present publication. The housing contains a channel in which a fluid flows. The valve is provided in the channel and configured to open or close the channel through rotational displacement. The shaft is configured to rotate integrally with the valve. The resin seal ring is configured to seal a gap between an inner wall of a channel member forming the channel and the valve when the valve is fully closed.The spring made of a metal is arranged in a ring shape in a region within a width of the sealing ring in the radial direction and is configured to press the sealing ring radially outward or inward with respect to a sealing counterpart.

[0011] The manufacturing method of the valve device includes a first assembly process, a heat treatment process, and a second assembly process. In the first assembly process, the components of the valve device, which includes the valve, the seal ring, and the spring, are assembled. In the heat treatment process, the seal ring is heated to a predetermined treatment temperature in a state where the spring is installed in the seal ring, and the seal ring is placed between the valve and the inner wall of the channel to cause the seal ring to plastically deform due to the tension of the spring, so that the seal ring follows a shape of the sealing counterpart. The treatment temperature of the heat treatment process is preferably set in a temperature range in which the spring tension exceeds a yield point and which is lower than a melting point of the seal ring.In the second assembly process after the heat treatment process, components of the valve device other than those assembled in the first assembly process are assembled.

[0012] In the valve device manufacturing method described in the present disclosure, the seal ring can be plastically deformed by the tension of the spring so that the seal sealing the seal ring follows a shape of its sealing counterpart during the heat treatment process. Therefore, the sealing performance when the valve is fully closed can be improved, regardless of variations in the dimensions and roundness of the components.

[0013] Preferably, the manufacturing method of the valve device further includes a welding process in which the valve is welded to the shaft after the first assembly process, and the heat treatment process is also performed in the welding process using the heat generated in the welding process. Therefore, the heat treatment process, which only aims at plastic deformation of the seal ring, can be omitted. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings: Fig. 1 is a schematic section showing an EGR valve device. Fig. Figure 2 is an enlarged sectional view showing an area II in Fig. 1 shows. Fig. 3 is a sectional view showing a passage when a valve according to a first embodiment is fully closed. Fig. 4 is a section along a line IV-IV in Fig. 3 in radial direction. Fig. 5 is a flowchart showing a manufacturing method of a valve device according to the first embodiment. Fig. 6 is an explanatory view showing a treatment temperature in a heat treatment process. Fig. 7 is a sectional view showing a channel with the valve fully closed according to a second embodiment. Fig. 8 is a sectional view showing a passage when a valve according to a third embodiment is fully closed. Fig. 9 is a sectional view showing a passage when a valve according to a fourth embodiment is fully closed. Fig. 10 is a sectional view showing a passage when a valve according to a fifth embodiment is fully closed. Fig. 11 is a sectional view showing a passage when a valve is fully closed in a comparative example. Fig. 12 is a section along a line XII-XII in Fig. 11 in radial direction. Fig. 13 is a flowchart showing a manufacturing method for a valve device of the comparative example. DESCRIPTION OF EMBODIMENTS

[0015] Hereinafter, several embodiments of a valve device and a manufacturing method for the valve device will be described with reference to drawings. The same reference numerals are given to the same structures in several embodiments, and explanations therefor will be omitted. The first to fifth embodiments will be referred to as the present embodiment, comprehensively. A seal ring used for the valve device in the present embodiment and made of a resin can be applied to a valve device configured to open or close a passage for EGR gas and control an opening of the passage for EGR gas in an EGR system in which part of the exhaust gas is recirculated to an air intake passage. [Structure of the valve device]

[0016] The Fig. 1 and Fig. 2 show schematic structures of the valve device. The Fig. 1 and Fig. 2 show a sealing ring 301 in the first embodiment as a representative of the sealing ring and a valve 70 in the first, second and third embodiments as a representative of a valve.

[0017] A valve device 90 includes a housing 91 containing a passage 80 for the EGR gas, the valve 70, which is a throttle valve configured to rotate integrally with a shaft 95 in the housing 91 and to open or close a passage through rotation and displacement, a sensor housing 96, and the like. The valve 70 is configured to rotate on a passage element 81 in the passage 80 in the housing 91. In the Fig. 1 and Fig. In the structure shown in Figure 2, the channel member 81 includes a nozzle inserted into a bore of the housing 91. An inner wall of the nozzle corresponds to an inner wall of the channel member 81. Thus, the housing 91 is made of an aluminum alloy and formed by die-casting, and the nozzle is made of stainless steel, which has excellent heat and corrosion resistance, and the like.

[0018] The bearings 92, 94 are provided in the housing 91 and rotatably support the shaft 95. A sealing element 93 is provided between the bearing 92 and the bearing 94. The rotation of an unillustrated motor is reduced in speed and transmitted to the shaft 95, and the shaft 95 rotates. The valve 70 is fixed to one end of the shaft 95 and is inclined relative to an axis of the stem 95. The valve 70 rotates integrally with the shaft 95 and controls an opening of the channel 80. The sensor housing 96 houses a rotation angle sensor 97 configured to detect an opening degree of the valve 70 by detecting a rotation angle of the shaft 95. A return spring 98 urges the valve 70 in a direction to close the valve 70.

[0019] The valve 70 has a disc shape with an axis O as its center. An outer circumferential groove 75 is formed over the entire circumference of the valve 70 at an outer circumferential edge of the valve 70 and has a rectangular cross section. The seal ring 301 made of a resin is housed in the outer circumferential groove 75. A metal spring 50 is installed on the seal ring 301. The seal ring 301 has a flat shape and is molded from a resin such as PPS, PTFE, PEEK, or the like. The seal ring 301 can be elastically deformed and is configured to seal a gap between the valve 70 and an inner wall 84 of the passage member 81 when the valve 70 is fully closed. The spring 50 is formed by a metal wire having a spring property and annularly arranged in a region within a width of the seal ring 301 in the radial direction.

[0020] The shape of the valve and the detailed structure of the seal ring in which the spring 50 is installed are different in each embodiment. The structures of the valve, seal ring, and the like, as well as the manufacturing method of the valve device for each embodiment, are described below. A reference numeral of the seal ring in each embodiment includes an embodiment number in the third position after "30." (First embodiment)

[0021] The structure of the valve device in the first embodiment will be described with reference to Fig. 3 and Fig. 4. In Fig. 3, the EGR gas flows in a flow direction from an upstream end surface 71 of the valve 70 to a downstream end surface 72 of the valve 70. The outer circumferential groove 75 of the valve includes a groove inner wall 751 on an upstream side, a groove inner wall 752 on a downstream side, and a groove bottom wall 753. The outer circumferential groove 75 accommodates the seal ring 301 in the first embodiment. This structure is the same as in the second and third embodiments.

[0022] In a state where the outer peripheral groove 75 accommodates the seal ring 301, an outer peripheral surface 34 of the seal ring 301 is placed on a radially outer side of an outer peripheral surface 73 of the valve 70, and an inner peripheral surface 33 of the seal ring 301 is fitted into the outer peripheral groove 75. When the valve is fully closed, the outer peripheral surface 34 of the seal ring 301 abuts against the inner wall 84 of the passage member 81. At this point, ideally, an entire outer peripheral surface 34 evenly abuts against the inner wall 84, and the sealing performance is ensured. The pressure of the gas flowing in the flow direction is applied to one end surface 31 of the seal ring 301, and the other end surface 32 of the seal ring 301 is pressed onto the groove inner wall 752 on the downstream side of the outer circumferential groove 75.

[0023] A cross-section of the seal ring 301 has a rectangular shape in the axial direction and is surrounded by one end surface 31 of the seal ring 301, the other end surface 32 of the seal ring 301, the inner peripheral surface 33, and the outer peripheral surface 34. This structure is common to all embodiments. In the first embodiment, a spring groove 36 is recessed radially outward from the inner peripheral surface 33. The spring 50 is installed in the spring groove 36 formed in the inner peripheral surface 33 of the seal ring 301 and is annularly placed in the area within the width of the seal ring 301 in the radial direction.

[0024] In addition, an original diameter of the spring 50 is adjusted so that an outer diameter of the spring 50 is slightly larger than an inner diameter of a groove bottom wall 364 of the spring groove 36. The spring 50 installed in the spring groove 36 therefore abuts against the groove bottom wall 364 of the spring groove 36 and presses the sealing ring 301 with a tension Fo in the radial direction outwards. As shown in Fig. 4, the sealing ring 301 is pressed radially outward from a center O so that the outer peripheral surface 34 abuts omnidirectionally against the inner wall 84 of the channel element 81.

[0025] In addition, the sealing ring 301 includes a cut 39 at a location in the circumferential direction so that the sealing ring 301 can expand and reduce in diameter. Fig. 4, the cut portion 39 is formed by simply cutting off the seal ring 301. However, in practice, as in Patent Document 1, the cut portion 39 may be formed so that the circumferential ends of the seal ring overlap each other in the radial and axial directions. When assembling the seal ring 301 with the outer circumferential groove 75 of the valve, a worker cuts off the cut portion 39 to temporarily enlarge the diameter of the seal ring 301 through elastic deformation, and inserts the seal ring 301 into the outer circumferential groove 75. After insertion, the diameter of the seal ring 301 is reduced. In addition, when used for the valve device 90, the diameter of the seal ring 301 is enlarged by gas pressure, and the cut portion 39 is separated.However, when the valve is fully closed, the play of the cut-off part 39 is eliminated and the ends of the sealing ring 301 are in close contact.

[0026] The following is a flow chart in Fig. 5, a process of the manufacturing method of the valve device in the present embodiment is described. In a first assembly process S1, some components of the valve device 90 are assembled. For example, as shown in Fig. 1, the nozzle forming the channel element 81 is inserted into a bore of the housing 91. Subsequently, the sealing ring 301, in combination with the spring 50, is inserted into the outer circumferential groove 75 of the valve 70. Furthermore, the shaft 95 is assembled with the bearing 92, the sealing element 93, and the bearing 94 are assembled with the housing 91. At this point, the end of the shaft 95 is inserted into the hole of the valve 70, which is inserted into the channel 80.

[0027] After the first assembly process S1, the next process can be selected from two samples, including a sample A and a sample B. In sample A, a welding process S2 and a heat treatment process S3A are performed sequentially. In the welding process S2, the valve 70 is welded to the shaft 95 by plasma welding, laser welding, or the like. In the heat treatment process S3A, the seal ring 301 is heated to a predetermined treatment temperature in a state where the spring 50 is installed in the seal ring 301 and the seal ring 301 is placed between the valve 70 and the inner wall 84 of the passage member 81. Then, the seal ring 301 is plastically deformed by the stress Fo of the spring 50 so that the seal ring 301 assumes the shape of a sealing counterpart.

[0028] In Sample B, however, the heat treatment process is performed in conjunction with the welding process, utilizing the heat generated during the welding process. This means that a welding and heat treatment process S3B is performed. This allows the heat treatment process, which only aims at the plastic deformation of the sealing ring 301, to be omitted. In practice, the heat from the weld is transferred to the sealing ring 301 unless heat insulation is actively performed in the welding process S2 of Sample A.

[0029] The heat treatment process S3A of Sample A and the welding and heat treatment process S3B are hereinafter collectively referred to as heat treatment process S3. In the manufacturing method for the valve device in the first embodiment, the heat treatment process S3 is performed such that the outer circumferential groove 75 of the valve accommodates the seal ring 301, and the outer circumferential surface 34 of the seal ring 301 abuts the inner wall 84 of the channel member 81. The seal ring 301 is plastically deformed radially outward by the spring tension Fo such that the outer circumferential surface 34 follows a shape of the inner wall 84, i.e., the sealing counterpart, of the channel member 81. This structure is the same as in the second and third embodiments.

[0030] In a second assembly process S4 following the heat treatment process S3, components of the valve device 90 other than those assembled in the first assembly process S1 are assembled, and a product is completed. The components assembled in the first assembly process S1 or the second assembly process S4 are not limited to the example described above and can be selected accordingly.

[0031] The setting of the treatment temperature of the heat treatment process S3 is based on Fig. 6 described. In Fig. 6, a horizontal axis shows the temperature, while a vertical axis shows the yield stress Y of the seal ring and the spring stress F. The yield stress Y of the seal ring made of a resin is reduced along a curve as the temperature is increased from a low temperature region to a high temperature region. When the temperature reaches a melting point Mp, the seal ring melts. In addition, the stress F of the metal spring is reduced as the temperature is increased from the low temperature region to the high temperature region. However, the reduction rate of the spring stress F is smaller than the reduction rate of the yield stress Y.

[0032] In Fig. 6, in a case where the spring stress F is set to F1, the yield strength Y is equal to the spring stress F1 when the temperature is an equilibrium point Eq. In the temperature range below the equilibrium point Eq, the spring stress F1 is lower than the seal ring yield strength Y, and as a result, the seal ring is essentially not plastically deformed even if the spring stress F1 acts on the seal ring. In the temperature range above the equilibrium point Eq, the spring stress F1 is higher than the seal ring yield strength Y, and as a result, the seal ring is plastically deformed by the spring stress F1. Therefore, the treatment temperature of the heat treatment process S3 is set in the temperature range higher than the equilibrium point Eq and lower than the melting point of the seal ring.

[0033] Depending on the design of the spring, the spring stress F may exceed the yield point Y regardless of the temperature range, such as when the spring stress F is indicated by F2. In this case, in a working temperature range of the product, the spring stress F2 exceeding the yield point Y is constantly exerted on the seal ring, and as a result, the fatigue strength of the seal ring may be reduced. In addition, if the spring stress F is increased more than required, the spring must be larger, which may lead to higher costs. That is, the spring stress F is preferably set to be lower than the yield point Y at normal temperature. Furthermore, for example, an upper limit of the working temperature range is preferably set slightly lower than the equilibrium point Eq or slightly above the equilibrium point Eq.

[0034] In the welding and heat treatment process S3B, which utilizes heat in the welding process, a relationship between a parameter of a welding condition and a temperature transferred to the seal ring can be established in advance according to an experiment or simulation, and a heat treatment temperature can be feedforward-controlled by controlling the welding condition. The temperature of the seal ring can be controlled within a range of the treatment temperature, for example, by controlling an applied voltage and exposure time in plasma welding, or by controlling the laser intensity and irradiation time in laser welding. Furthermore, an actual temperature of the seal ring can be detected by a temperature sensor, and feedback control can be performed to achieve a target temperature.

[0035] In a comparative example, the effects of the manufacturing method of the valve device in the first embodiment will be described in comparison with a manufacturing method of a valve device. In the comparative example, a seal ring 309 made of a resin is used alone, without incorporating the spring 50. In a mass production process, variations occur in the outer diameter and roundness of the seal ring 309, as well as in the inner diameter and roundness of the channel 80. In particular, the deformation and dimensional dispersion of the seal rings 309, which are resin molds, are relatively larger due to the molding state, storage conditions after molding, and stresses caused during assembly.

[0036] As in Fig. 11 and Fig. As shown in Figure 12, in the valve device in which the outer circumferential groove 75 of the valve 70 accommodates the seal ring 309 without the spring 50, the seal ring 309 is not pressed outward in the radial direction. Therefore, for example, when an outer diametrical shape of the seal ring 309 is deformed into an ellipse, even when the valve is fully closed, a clearance is generated in the radial direction between the outer circumferential surface 34 of the seal ring 309 and the inner wall 84 of the channel member 81 depending on a position in the circumferential direction, and the sealing performance may decrease. As can be seen from a flowchart in Fig. 13, the manufacturing method of the valve device in the comparative example includes three processes composed of the first assembling process S1, the welding process S2, and the second assembling process S4, and does not include the heat treatment process S3, unlike the manufacturing method in the first embodiment.

[0037] The Fig. The comparative example shown in Figure 13 includes not only a case where the seal ring 309 is manufactured without the spring 50, but also, for example, a case where the seal ring 301 including the spring 50 is manufactured without heat treatment, similar to the first embodiment. Compared to the case where the seal ring 309 made of a resin is used without the spring 50, a certain shape correction effect can be achieved by providing the spring 50 and applying stress at normal temperature. As shown in Fig. However, as shown in Figure 6, due to the relationship between the spring stress F and the seal ring yield strength Y, the plastic deformation performed in the normal temperature range may be insufficient. Furthermore, as described above, the condition where the spring stress F exceeds the yield strength Y in the normal temperature range is not preferable from the perspective of the seal ring's fatigue strength.

[0038] In the first embodiment, from the comparative example, a structural difference is that the spring 50 is installed in the spring groove 36 of the seal ring 301, and a manufacturing method difference is that the heat treatment process is performed under the application of the spring tension Fo. In the first embodiment, in the heat treatment process S3, the seal ring 301 is plastically deformed outward in the radial direction by the spring tension Fo, so that the outer peripheral surface 34 follows the shape of the inner wall 84 of the passage member 81. That is, the sealing performance when the valve is fully closed can be ensured regardless of the dimensional variations and roundness of the components.By setting the treatment temperature of the heat treatment process S3 in the temperature range above the equilibrium point Eq and below the melting point Mp of the sealing ring, the sealing ring 301 can also be plastically deformed accordingly.

[0039] The valve device in the second to fifth embodiments is described with reference to Fig. 7 to 10, which are sectional views showing the channel with the valve completely closed, similar to Fig. 3 in the first embodiment. In the second to fourth embodiments, similar to the first embodiment, the sealing counterpart of a seal ring 302, 303, 304 is the inner wall 84 of the channel element 81, and the spring 50 presses the seal ring 302, 303, 304 radially outward. In the fifth embodiment, however, the sealing counterpart of a seal ring 305 is an outer peripheral wall 783 of a valve 78, and the spring 50 presses the seal ring 305 radially inward. (Second embodiment)

[0040] The second embodiment will be described with reference to Fig. 7 below. In the second embodiment, the spring 50 is installed in a spring groove 35 formed in one end face 31 of the sealing ring 302 and arranged annularly in a radial direction in a region within a width of the sealing ring 302. The spring 50 installed in the spring groove 35 abuts against a groove inner wall 354 on a radially outer side of the spring groove 35 and presses the sealing ring 302 radially outward with the tension Fo. (Third embodiment)

[0041] The third embodiment will be described with reference to Fig. 8. In the third embodiment, the spring 50 is embedded in the seal ring 303 and arranged annularly in a region within a width of the seal ring 303 in the radial direction. Typically, the spring 50 is formed in the seal ring 303 by insert molding. The formed spring 50 presses the seal ring 303 radially outward with the tension Fo. (Fourth embodiment)

[0042] The fourth embodiment will be described with reference to Fig. 9. In the fourth embodiment, a valve 77 does not include an outer circumferential groove. In addition, the seal ring 304 includes a spring groove 38 radially outward from the inner circumferential surface 33, and the outer circumferential surface 34 abuts the inner wall 84 of the passage member 81 when the valve is fully closed. The peripheral parts 771, 772 of the valve 77 are fitted into a pair of flanges 371, 372 forming walls on either side of the spring groove 38 in the axial direction. The spring 50 fitted into the spring groove 38 abuts a groove bottom wall 384 of the spring groove 38 and urges the seal ring 304 radially outward with the tension Fo. WO 2006 / 080273 specifies the structure in which the peripheral parts 771, 772 of the valve 77 are inserted into the flanges 371, 372, without the structure in which the spring 50 is inserted into the spring groove 38 of the sealing ring 304.

[0043] In the manufacturing method for the valve device in the fourth embodiment, the heat treatment process S3 is performed so that the outer peripheral surface 34 of the seal ring 304 conforms to the inner wall 84 of the passage member 81. The seal ring 304 is plastically deformed radially outward by the spring tension Fo so that the outer peripheral surface 34 follows the shape of the inner wall 84 of the passage member 81 as a sealing counterpart. Therefore, similar to the above-described embodiment, the sealing performance can be ensured when the valve is fully closed, regardless of the dimensional variations and roundness of the components. (Fifth embodiment)

[0044] The fifth embodiment will be described with reference to Fig.10. In the fifth embodiment, the valve 78 does not include the outer peripheral groove. In addition, the channel member 81 and a bulb member 82 form a housing groove 85 on the inner wall 84 of the channel member 81. An outer peripheral side of the seal ring 305 is housed in the housing groove 85, while the inner peripheral surface 33 is exposed from the housing groove 85 to an inner side of the channel. As the dashed line shows, the valve 78 rotates about a rotation axis Q while the seal ring 305 is fixed. When the valve is fully closed, the outer peripheral wall 783 of the valve 78 abuts against the inner peripheral surface 33 of the seal ring 305.

[0045] Similar to the second embodiment, the spring 50 is inserted into the spring groove 35 formed in one end surface 31 of the sealing ring 305. However, unlike the second embodiment, the initial diameter of the spring 50 is adjusted so that the spring 50 radially abuts against an inner groove wall 353 attached to the inside of the spring groove 35 and presses the sealing ring 305 radially inward with a tension Fi. DE 10 2014 222 517 A1 shows the structure in which the valve 78 rotates while the sealing ring 305 housed in the housing groove 85 of the channel element 81 is fixed, without the structure in which the spring 50 is inserted into the spring groove 35 of the sealing ring 305.

[0046] In the manufacturing method for the valve device in the fifth embodiment, the heat treatment process S3 is performed so that the inner peripheral surface 33 of the seal ring 305 conforms to the outer peripheral wall 783 of the valve 78. The seal ring 305 is plastically deformed inward in the radial direction by the spring tension Fi, so that the inner peripheral surface 33 follows a shape of the outer peripheral wall 783 of the valve 78, that is, the sealing counterpart. Therefore, similar to the above embodiment, the sealing performance can be ensured when the valve is fully closed, regardless of the dimensional variations and roundness of the components. (Other embodiments)

[0047] The manufacturing method for the valve device in this disclosure can also be applied to a throttle valve device in which intake gas flows, to various on-off valves to which a throttle valve is attached, to a flow control valve, to a pressure control valve, and the like, not only to the EGR valve device.

[0048] The present disclosure is not limited to the above-mentioned embodiments and / or modifications, but may be further modified in various ways without departing from the spirit of the present disclosure.

[0049] The present disclosure has been described according to the present embodiments. However, the present disclosure is not limited by the embodiments or structure. The present disclosure encompasses various variations and modifications within the equivalents. The present disclosure also encompasses various combinations and embodiments, and further encompasses one or more or fewer elements and combinations thereof.

Claims

[1] A method of manufacturing a valve device (90) comprising: a housing (91) containing a channel (80) in which a fluid flows; a valve (70, 77, 78) provided in the channel (80) and configured to open or close the channel (80) by rotational displacement; a shaft (95) configured to rotate integrally with the valve (70, 77, 78); a sealing ring (301 to 305) made of a resin and configured to seal a gap between an inner wall (84) of a channel member (81) forming the channel (80) and the valve (70, 77, 78) when the valve (70, 77, 78) is fully closed; and a spring (50) made of a metal, which is annularly arranged in a region within a width of the seal ring (301 to 305) in a radial direction and is configured to press the seal ring (301 to 305) radially outward or inward with respect to a seal counterpart; the manufacturing process comprising the following steps: Assembling in a first assembly process (S1) the components of the valve device (90) comprising the valve, the sealing ring (301 to 305) and the spring (50); Heating the sealing ring (301 to 305) in a heat treatment process (S3) to a predetermined treatment temperature in a state in which the spring (50) is installed in the sealing ring (301 to 305) and the sealing ring (301 to 305) is arranged between the valve (70, 77, 78) and the inner wall (84) of the channel (80) to cause the sealing ring (301 to 305) to plastically deform due to the tension of the spring (50) so that the sealing ring (301 to 305) follows a shape of the sealing counterpart; and Assembling in a second assembly process (S4) other components of the valve device (90) than the components assembled in the first assembly process (S1). [2] A manufacturing method for the valve device (90) according to claim 1, wherein the treatment temperature of the heat treatment process is set in a temperature range in which the tension of the spring (50) exceeds a yield point of the seal ring (301 to 305) and which is lower than a melting point of the seal ring (301 to 305). [3] A manufacturing method for the valve device (90) according to claim 1 or 2, further comprising: Welding, in a welding process (S2), the valve to the shaft (95) after the first assembly process (S1), wherein the heat treatment process is also carried out in the welding process (S2) by utilizing the heat generated in the welding process (S2). [4] A manufacturing method for the valve device (90) according to any one of claims 1 to 3, wherein the heat treatment process is performed in a state in which the seal ring (301 to 305) is accommodated in an outer peripheral groove (75) of the valve (70) and in which an outer peripheral surface (34) of the seal ring (301 to 305) abuts against the inner wall (84) of the channel member (81). [5] Manufacturing method for the valve device (90) according to one of claims 1 to 3, wherein a spring groove (38) is formed in an inner peripheral surface (33) of the sealing ring (301 to 305), a pair of flanges (371, 372) forming walls on each side of the spring groove (38) in the axial direction, and the heat treatment process is carried out in a state in which peripheral parts (771, 772) of the valve (77) are inserted into the pair of flanges (371, 372) and in which an outer peripheral surface (34) of the seal ring (301 to 305) abuts the inner wall (84) of the channel member (81). [6] A manufacturing method for the valve device (90) according to any one of claims 1 to 3, wherein the heat treatment process is performed in a state in which the seal ring (301 to 305) is housed in a housing groove (85) formed on the inner wall (84) of the channel member (81) and in which an inner peripheral surface (33) of the seal ring (301 to 305) abuts against an outer peripheral wall (783) of the valve (78).

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