Valve device manufacturing method

Abstract

To fix a plurality of valve elements corresponding to a plurality of valve seats to one valve shaft while securing a degree of freedom, in a valve device having a multi-way poppet valve structure.SOLUTION: A valve device 1 includes: a housing 3 having a flow passage 2; two valve seats 4, 5 disposed in the flow passage; two valve elements 6, 7 capable of sitting on the valve seats; a valve shaft 8 provided with a valve element; a step motor 9 including a rotor 23 for reciprocating the valve shaft; and a female screw 31 of the rotor engaged with a male screw 10 disposed on the valve shaft. The flow passage is divided into a near side and a far side to the stepping motor with respect to the valve seats as a boundary, and the valve elements are respectively disposed in the divided flow passages. The housing is divided into a first housing portion 41 and a second housing portion 42. A manufacturing method of the valve device includes: a process for fixing each of the valve elements to the valve shaft projecting to at least one of flow passages of both housing portions; and a process for connecting both housing portions so that the valve seats are disposed on the same shaft in series, and the valve elements are matched to the valve seats thereafter.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a method of manufacturing a valve device that has a poppet valve structure in which a valve element moves perpendicularly from a seat portion of a valve seat and controls the flow of a fluid. [Background technology]

[0002] A known example of this type of technology is the "EGR valve" described in Patent Document 1 listed below. This EGR valve includes a housing having a flow path, a valve seat provided in the flow path, a valve element provided so as to be able to seat on the valve seat, a valve stem provided with the valve element, the valve stem having one end and the other end, the valve element fixed to the one end and a male thread provided to the other end, an actuator for reciprocating the valve stem in its axial direction, the actuator including a rotor having a female thread that is threaded onto the male thread, the flow path being divided into a side near the rotor and a side far from the rotor by the valve seat, and the valve element being arranged in the near side flow path so as to be able to seat on the valve seat, and the structure of a so-called inward-opening two-way poppet valve is disclosed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-3237 Summary of the Invention [Problem to be solved by the invention]

[0004] While Patent Document 1 discloses the structure of an inward-opening two-way poppet valve, it is possible to envision a valve device having a multi-way (e.g., three-way) poppet valve structure in which multiple (e.g., two) valve bodies are arranged in series on a valve stem and multiple (e.g., two) valve seats corresponding to the valve bodies are arranged in a flow path. However, Patent Document 1 did not particularly disclose a manufacturing method applicable to an inward-opening two-way poppet valve, nor a manufacturing method for a valve device having a multi-way poppet valve structure.

[0005] The disclosed technology has been made in consideration of the above circumstances, and its first object is to provide a manufacturing method for a valve device having a so-called multi-way poppet valve structure, which enables multiple valve elements corresponding to multiple valve seats to be fixed to a single valve stem while ensuring a degree of freedom. Also, its second object is to provide a manufacturing method for a valve device having a so-called two-way poppet valve structure, which enables one valve element corresponding to one valve seat to be fixed to a single valve stem while ensuring a degree of freedom. [Means for solving the problem]

[0006] In order to achieve the above object, the technology described in claim 1 includes a housing having a fluid flow path, a plurality of valve seats arranged in series on the same axis in the flow path, a plurality of valve bodies arranged so as to be able to seat on each of the plurality of valve seats, a valve stem having a plurality of valve bodies arranged in series on the same axis, the valve stem having one end side and the other end side, the plurality of valve bodies being fixed to the one end side and a first screw being provided on the other end side, an actuator for reciprocating the valve stem in its axial direction, the actuator including a rotor having a second screw threadedly engaged with the first screw, the flow path being divided into a side close to the actuator and a side far from the actuator with each valve seat as a boundary, and an actuator. In a manufacturing method of a valve device in which corresponding valve elements are arranged so as to be able to seat on valve seats on the side closer to the actuator or the side farther from the actuator, the housing is divided into a first housing portion and a second housing portion near the valve seat closest to the actuator among the plurality of valve seats, and the method includes the steps of fixing the plurality of valve elements to one end of a valve shaft protruding into a flow path of at least one of the first housing portion and the second housing portion, and connecting the first housing portion and the second housing portion after the valve elements are fixed so that the plurality of valve seats are arranged in series on the same axis and the plurality of valve elements are aligned with the corresponding valve seats.

[0007] According to the configuration of the above technology, after multiple valve bodies are fixed to one end of a valve stem that protrudes into a flow path in at least one of the first and second housing parts, multiple valve seats are arranged in series on the same axis, and the first and second housing parts are joined so that the multiple valve bodies are aligned with the corresponding valve seats. Therefore, it is possible to assemble multiple valve bodies onto the valve stem without being restricted by the flow paths or valve seats of the housing.

[0008] In order to achieve the above object, the technology described in claim 2 comprises a housing having a fluid flow path, a plurality of valve seats arranged in series on the same axis in the flow path, a plurality of valve bodies arranged so as to be able to be seated in correspondence with the plurality of valve seats, a valve stem having a plurality of valve bodies arranged in series on the same axis, the valve stem having one end side and the other end side, the plurality of valve bodies being fixed to the one end side and a first screw being provided to the other end side, an actuator for reciprocating the valve stem in the axial direction, the actuator including a rotor having a second screw threadedly engaged with the first screw, and the flow path being divided into two sections adjacent to the actuator with each valve seat as a boundary. In a method for manufacturing a valve device in which the housing is divided into a side closer to the actuator and a side farther from the actuator, and corresponding valve elements are arranged on the side closer to the actuator or the side farther from the actuator so that they can be seated on valve seats, the housing includes an assembly hole in the flow path that has a diameter larger than the diameter of at least the valve element assembled at a position closest to the actuator and that is capable of holding the valve seat, and the method includes the steps of fixing at least one valve element via the assembly hole to one end of a valve stem that protrudes into the flow path of the housing, and assembling at least one valve seat into the assembly hole after the valve element is fixed.

[0009] According to the configuration of the above technology, at least one valve element is fixed via an assembly hole to one end of the valve stem that protrudes into the flow path of the housing, and then at least one valve seat is assembled into the assembly hole. Therefore, it is possible to assemble multiple valve elements onto the valve stem without dividing the housing and without being restricted by the flow path or the valve seat.

[0010] In order to achieve the above object, the technology described in claim 3 is directed to the method for manufacturing a valve device described in claim 1 or 2, further comprising an assembled valve body in which multiple valve bodies are integrally assembled, and in the step of fixing the multiple valve bodies, the assembled valve body is assembled to one end of a valve shaft, and after the assembly, the assembled valve body is fixed to the valve shaft at the end of the one end of the valve shaft.

[0011] According to the configuration of the above technology, in addition to the effect of the technology of claim 1 or 2, in the step of fixing the plurality of valve bodies, the assembled valve body is assembled to one end of the valve shaft, and then the assembled valve body is fixed to the valve shaft at the end of the one end of the valve shaft. Therefore, the number of steps is less than when fixing the plurality of valve bodies individually to the valve shaft.

[0012] In order to achieve the above object, the technology described in claim 4 is directed to the method for manufacturing a valve device described in claim 1 or 2, wherein the valve element closest to the actuator among the multiple valve elements on the valve stem is arranged in the flow passage closest to the actuator or on the opposite side of the flow passage, with the corresponding valve seat as a boundary; the valve element farthest from the actuator among the multiple valve elements on the valve stem is arranged in the flow passage close to the actuator or on the opposite side of the flow passage, with the corresponding valve seat as a boundary; and a flow passage spring is provided on the valve stem between the nearest valve element and the inner wall of the flow passage closest to the actuator, adjacent to the corresponding valve seat, for urging the nearest valve element in a direction to seat it on its corresponding valve seat or for urging the farthest valve element in a direction to seat it on its corresponding valve seat.

[0013] According to the configuration of the above technology, in addition to the effects of the technology described in claim 1 or 2, a flow path spring is provided on the valve stem between the valve element closest to the actuator and the inner wall of the flow path adjacent to the corresponding valve seat on the side closest to the actuator. This flow path spring urges the valve elements together with the valve stem in a direction away from the actuator, thereby urging the closest valve element in a direction to seat on its corresponding valve seat or the farthest valve element in a direction to seat on its corresponding valve seat. Therefore, when the valve elements are assembled to the valve stem, they can be assembled in a stable position.

[0014] In order to achieve the above object, the technology described in claim 5 is directed to the method for manufacturing a valve device described in claim 1 or 2, in which the actuator further includes an actuator spring for urging the multiple valve bodies together with the valve shaft in a direction approaching the actuator.

[0015] According to the configuration of the above technology, in addition to the effect of the technology described in claim 1 or 2, the actuator spring urges the multiple valve bodies together with the valve stem in a direction approaching the actuator. Therefore, the backlash (play) between the first thread of the valve stem and the second thread of the rotor, which are threaded together, is offset, and the valve stem is coupled to the rotor.

[0016] In order to achieve the above object, the technology described in claim 6 is directed to the method for manufacturing a valve device described in claim 3, wherein the actuator further includes an actuator spring for urging the multiple valve bodies together with the valve shaft in a direction approaching the actuator.

[0017] According to the configuration of the above technology, in addition to the effect of the technology described in claim 3, the actuator spring urges the multiple valve bodies together with the valve stem in a direction approaching the actuator. Therefore, the backlash (play) between the first thread of the valve stem and the second thread of the rotor, which are threadedly engaged with each other, is offset, and the valve stem is coupled to the rotor.

[0018] In order to achieve the above object, the technology described in claim 7 is directed to the method for manufacturing a valve device described in claim 4, wherein the actuator further includes an actuator spring for urging the plurality of valve bodies together with the valve shaft in a direction approaching the actuator.

[0019] According to the configuration of the above technology, in addition to the effect of the technology described in claim 4, the actuator spring urges the multiple valve bodies together with the valve stem in a direction approaching the actuator. Therefore, the backlash (play) between the first thread of the valve stem and the second thread of the rotor, which are threadedly engaged with each other, is offset, and the valve stem is coupled to the rotor.

[0020] In order to achieve the above object, the technology described in claim 8 is the valve device manufacturing method described in claim 1 or 2, wherein the valve device is a three-way valve including one inlet and two outlets communicating with a flow path in a housing, the plurality of valve seats including a first valve seat closest to the actuator and a second valve seat next to the first valve seat closest to the actuator, and the flow path includes a first flow path portion closest to the actuator across the first valve seat, a second flow path portion between the first valve seat and the second valve seat, and a third flow path portion farthest from the actuator across the second valve seat. one of the two outlets communicates with the first flow path portion and the other communicates with the third flow path portion, the inlet communicates with the second flow path portion, the multiple valve bodies include a first valve body corresponding to the first valve seat and a second valve body corresponding to the second valve seat, the first valve body and the second valve body being provided on a valve stem in the second flow path portion, the first valve body having a conical shape and a tapered sealing surface on its outer periphery, the sealing surface being capable of being seated on the first valve seat, and the second valve body having a flat plate shape and a flat sealing surface on its periphery, the sealing surface being capable of being seated on the second valve seat.

[0021] According to the configuration of the above technology, in addition to the effect of the technology described in claim 1 or 2, of the two valve bodies, the first valve body is conical and has a tapered seal surface on its outer periphery that can be seated on the first valve seat, while the second valve body is flat and has a flat seal surface on its periphery that can be seated on the second valve seat. Therefore, of the two valve bodies, the centering of the second valve body relative to the second valve seat is alleviated.

[0022] In order to achieve the above object, the technology described in claim 9 is a method for manufacturing a valve device comprising: a housing having a fluid flow path; a valve seat provided in the flow path; a valve disc provided so as to be able to seat on the valve seat; a valve stem provided with the valve disc; the valve stem having one end side and the other end side, the valve disc fixed to one end side and a first screw provided to the other end side; an actuator for reciprocating the valve stem in its axial direction; the actuator including a rotor having a second screw threaded onto the first screw; the flow path being divided by the valve seat into a side closer to the actuator and a side farther from the actuator, and the valve disc being arranged so as to be able to seat on the valve seat;

[0023] According to the configuration of the above technology, after the valve element is fixed to one end of the valve stem that protrudes into the flow path of the first housing part, the first housing part and the second housing part are joined so that the valve element is aligned with the valve seat. Therefore, it is possible to assemble the valve element onto the valve stem without being restricted by the flow path of the housing or the valve seat. [Effects of the Invention]

[0024] According to the technology described in claim 1, in a valve device having a multi-way poppet valve structure, multiple valve bodies corresponding to multiple valve seats can be fixed to one valve shaft while ensuring a degree of freedom.

[0025] According to the technology described in claim 2, in a valve device having a multi-way poppet valve structure, a plurality of valve bodies corresponding to a plurality of valve seats can be fixed to one valve shaft while ensuring a degree of freedom.

[0026] According to the technology described in claim 3, in addition to the effect of the technology described in claim 1 or 2, the number of steps can be reduced, thereby simplifying the manufacture of the valve device.

[0027] According to the technology recited in claim 4, in addition to the effect of the technology recited in claim 1 or 2, it is possible to improve the adhesion and sealing performance of the valve device when the valve body is fully closed.

[0028] According to the technology recited in claim 5, in addition to the effect of the technology recited in claim 1 or 2, it is possible to fix the valve body to the valve stem in a stable state.

[0029] According to the technology recited in claim 6, in addition to the effect of the technology recited in claim 3, it is possible to fix the valve body to the valve stem in a stable state.

[0030] According to the technology recited in claim 7, in addition to the effect of the technology recited in claim 4, it is possible to fix the valve disc to the valve stem in a stable state.

[0031] According to the technology recited in claim 8, in addition to the effect of the technology recited in claim 1 or 2, the coaxial precision of the valve body relative to the valve stem can be relaxed, and in that sense, the manufacture of the valve device can be simplified.

[0032] According to the technique of claim 9, in a valve device having a two-way poppet valve structure, the valve element can be fixed to one valve shaft while ensuring a degree of freedom. [Brief explanation of the drawings]

[0033] [Figure 1] FIG. 3 is a cross-sectional view showing a first opening / closing state of the valve device in the first embodiment. [Figure 2] FIG. 4 is a cross-sectional view showing a second opening / closing state of the valve device in the first embodiment. [Figure 3] FIG. 3 is an enlarged cross-sectional view showing a part of a step motor in a first open / close state of the valve device according to the first embodiment. [Figure 4]4 is an enlarged cross-sectional view showing a part of the state in which the male thread and the female thread in FIG. 3 are screwed together in the first embodiment. [Figure 5] FIG. 3 is an enlarged cross-sectional view showing a part of the step motor in the valve device in a second opening / closing state in the first embodiment. [Figure 6] 6 is an enlarged cross-sectional view showing a part of the state in which the male thread and the female thread in FIG. 5 are screwed together in the first embodiment. [Figure 7] FIG. 1 is a cross-sectional view illustrating the first embodiment, schematically showing the operating states of the first and second valve bodies and valve stem relative to the first and second valve seats, and a portion of the associated housing (first housing portion and second housing portion). [Figure 8] FIG. 1 is a cross-sectional view illustrating the first embodiment, schematically showing the operating states of the first and second valve bodies and valve stem relative to the first and second valve seats, and a portion of the associated housing (first housing portion and second housing portion). [Figure 9] FIG. 1 is a cross-sectional view illustrating the first embodiment, schematically showing the operating states of the first and second valve bodies and valve stem relative to the first and second valve seats, and a portion of the associated housing (first housing portion and second housing portion). [Figure 10] 5 is a cross-sectional view showing a part of a process in the final stage of assembling parts in the method for manufacturing the valve device according to the first embodiment. FIG. [Figure 11] 5 is a cross-sectional view showing a part of a process in the final stage of assembling parts in the method for manufacturing the valve device according to the first embodiment. FIG. [Figure 12] 5 is a cross-sectional view showing a part of a process in the final stage of assembling parts in the method for manufacturing the valve device according to the first embodiment. FIG. [Figure 13] 10 is a cross-sectional view showing a part of a process in the final stage of assembling parts in the method for manufacturing the valve device according to the second embodiment. FIG. [Figure 14] 10 is a cross-sectional view showing a part of a process in the final stage of assembling parts in the method for manufacturing the valve device according to the second embodiment. FIG. [Figure 15] 10 is a cross-sectional view showing a part of a process in the final stage of assembling parts in the method for manufacturing the valve device according to the second embodiment. FIG. [Figure 16]FIG. 11 is a cross-sectional view showing a part of a process in the final stage of assembling parts in the method for manufacturing the valve device according to the third embodiment. [Figure 17] FIG. 11 is a cross-sectional view showing a part of a process in the final stage of assembling parts in the method for manufacturing the valve device according to the third embodiment. [Figure 18] FIG. 11 is a cross-sectional view showing a part of a process in the final stage of assembling parts in the method for manufacturing the valve device according to the third embodiment. [Figure 19] FIG. 10 is a cross-sectional view illustrating the operating state of the first and second valve bodies and the valve stem relative to the first and second valve seats, and a portion of the associated housing (first housing portion and second housing portion) according to the fourth embodiment. [Figure 20] FIG. 10 is a cross-sectional view illustrating the operating state of the first and second valve bodies and the valve stem relative to the first and second valve seats, and a portion of the associated housing (first housing portion and second housing portion) according to the fourth embodiment. [Figure 21] FIG. 10 is a cross-sectional view illustrating the operating state of the first and second valve bodies and the valve stem relative to the first and second valve seats, and a portion of the associated housing (first housing portion and second housing portion) according to the fourth embodiment. [Figure 22] FIG. 10 is a cross-sectional view equivalent to FIG. 7 showing a second opening / closing state of the valve device according to the fifth embodiment. [Figure 23] 10 is a cross-sectional view equivalent to FIG. 9 showing a first open / close state of the valve device according to the fifth embodiment. [Figure 24] FIG. 24 is a cross-sectional view equivalent to FIG. 23 showing a first open / close state of the valve device according to the sixth embodiment. [Figure 25] FIG. 23 is a cross-sectional view equivalent to FIG. 22 showing a second opening / closing state of the valve device according to the sixth embodiment. [Figure 26] FIG. 13 is a cross-sectional view showing only the second valve seat and the second valve body according to the seventh embodiment. [Figure 27] FIG. 13 is a cross-sectional view showing only the second valve seat and the second valve body according to the seventh embodiment. [Figure 28] FIG. 13 is a cross-sectional view showing a second opening / closing state of the valve device according to the eighth embodiment. [Figure 29] FIG. 13 is a cross-sectional view showing a second opening / closing state of the valve device according to the eighth embodiment. [Figure 30] FIG. 13 is a cross-sectional view showing a first opening / closing state of the valve device according to the eighth embodiment. [Figure 31] FIG. 13 is a schematic configuration diagram showing a water flow switching device including a valve device according to an eighth embodiment. [Figure 32] 13 is a flowchart showing the contents of control when a coil abnormality occurs according to the eighth embodiment. [Figure 33] 13 is a flowchart showing the contents of valve opening position storage control according to the ninth embodiment. [Figure 34] FIG. 23 is a cross-sectional view showing a valve device according to a tenth embodiment. [Figure 35] FIG. 23 is a cross-sectional view showing a valve device according to a tenth embodiment. [Figure 36] FIG. 23 is a cross-sectional view showing a valve device according to an eleventh embodiment. [Figure 37] FIG. 23 is a cross-sectional view showing a valve device according to an eleventh embodiment. [Figure 38] FIG. 2 is a schematic view showing the configuration of a valve device according to the first embodiment. [Figure 39] FIG. 10 is a schematic diagram showing the configuration of a valve device according to another embodiment. [Figure 40] FIG. 10 is a schematic diagram showing the configuration of a valve device having a two-way poppet valve structure according to another embodiment. [Figure 41] FIG. 10 is a schematic view showing the configuration of a valve device according to a second embodiment. [Figure 42] FIG. 10 is a schematic diagram showing the configuration of a valve device according to another embodiment. [Figure 43] FIG. 10 is a schematic diagram showing the configuration of a valve device having a two-way poppet valve structure according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0034] Hereinafter, an embodiment embodying a method for manufacturing a valve device will be described.

[0035] First Embodiment First, the first embodiment will be described with reference to the drawings.

[0036] [Valve device configuration] FIG. 1 is a cross-sectional view of a valve device 1 according to this embodiment, showing a first open / closed state. FIG. 2 is a cross-sectional view of the valve device 1 according to this embodiment, showing a second open / closed state. As shown in FIGS. 1 and 2, the valve device 1 according to this embodiment is configured as a three-way valve having a poppet valve structure in which two valve elements 6, 7 move perpendicularly from seats 4a, 5a of corresponding valve seats 4, 5. The valve device 1 includes a housing 3 having a flow path 2, two valve seats 4, 5 arranged coaxially in series in the flow path 2, two valve elements 6, 7 arranged so as to be seatable on the two valve seats 4, 5, respectively, a valve shaft 8 on which the two valve elements 6, 7 are arranged coaxially in series, and a step motor 9 for reciprocating (stroking) the valve shaft 8 in its axial direction. In this embodiment, the step motor 9 corresponds to an example of an "actuator" in the technology disclosed herein.

[0037] The valve shaft 8 is disposed so as to pass vertically through the housing 3. The valve shaft 8 has one end side 8a (the lower end side in Figs. 1 and 2) and the other end side 8b (the upper end side in Figs. 1 and 2), with two valve bodies 6, 7 fixed to the one end side 8a and a male thread 10 provided on the other end side 8b. A flange-shaped spring retainer 11 is provided on the valve shaft 8 below and adjacent to the male thread 10. Below the spring retainer 11 of the valve shaft 8, a two-flat portion 8c having a substantially oval cross section is provided. In this embodiment, the male thread 10 corresponds to an example of the "first thread" of the disclosed technology.

[0038] In this embodiment, the valve device 1 is configured as a three-way valve in a housing 3, including one inlet 12 and two outlets 13, 14 that communicate with a flow path 2. The flow path 2 is divided into a side closer to the step motor 9 and a side farther from the step motor 9 by valve seats 4, 5, and valve elements 6, 7 corresponding to the side closer to the step motor 9 or the side farther from the step motor 9 are arranged so as to be able to seat on the valve seats 4, 5, respectively. That is, the two valve seats 4, 5 include a first valve seat 4 that is closest to the step motor 9 and a second valve seat 5 that is next closest to the step motor 9 after the first valve seat 4. The first valve seat 4 has a valve hole 4b that communicates with the flow path 2, and the second valve seat 5 has a valve hole 5b that also communicates with the flow path 2. The two valve elements 6, 7 include a first valve element 6 that corresponds to the first valve seat 4 and a second valve element 7 that corresponds to the second valve seat 5. The flow path 2 is divided by the first valve seat 4 into a first flow path section 15 closest to the step motor 9 and a second flow path section 16 farthest from the step motor 9. The first valve element 6 corresponding to the first valve seat 4 is arranged in the second flow path section 16 so as to be able to seat on the first valve seat 4. Meanwhile, the flow path 2 is divided by the second valve seat 5 into a second flow path section 16 close to the step motor 9 and a third flow path section 17 farthest from the step motor 9. The second valve element 7 corresponding to the second valve seat 5 is arranged in the second flow path section 16 so as to be able to seat on the second valve seat 5. One of the two outlets 13, 14 is the first outlet 13 which communicates with the first flow path section 15, and the other is the second outlet 14 which communicates with the third flow path section 17. The inlet 12 is in communication with the second flow path section 16.

[0039] The first valve body 6 and the second valve body 7 are mounted on the valve shaft 8 in the second flow path portion 16. The first valve body 6 is generally frusto-conical and has a tapered seal surface 6a on its outer periphery, which is capable of seating on the ridge-shaped seat portion 4a of the first valve seat 4. The second valve body 7 is disc-shaped and has a flat seal surface 7a on its periphery, which is capable of seating on the flat seat portion 5a of the second valve seat 5. In this embodiment, as shown in FIGS. 1 and 2, a rubber sheet 18 is provided on the inner periphery of the seat portion 5a of the second valve seat 5, protruding above the seat portion 5a and capable of coming into contact with the seal surface 7a of the second valve body 7.

[0040] In the first open / close state shown in FIG. 1 , the first valve element 6 is seated on the first valve seat 4, and the second valve element 7 is spaced upward from the second valve seat 5. In this first open / close state, as shown by the black arrow in FIG. 1 , fluid flowing from the inlet 12 into the second flow path section 16 flows to the third flow path section 17 and out through the second outlet 14. On the other hand, in the second open / close state shown in FIG. 2 , the first valve element 6 is spaced downward from the first valve seat 4, and the second valve element 7 is seated on the second valve seat 5. In this second open / close state, as shown by the black arrow in FIG. 2 , fluid flowing from the inlet 12 into the second flow path section 16 flows to the first flow path section 15 and out through the first outlet 13.

[0041] The housing 3 is provided with two thrust bearings 19, 20 for supporting the valve stem 8 so that it can make stroke movements in the axial direction. The inner periphery of the thrust bearing 19 is formed with a rotation restricting portion 19a having a generally oval cross section that can engage with the two-flat width portion 8c of the valve stem 8. The alignment of the two-flat width portion 8c with the rotation restricting portion 19a guides the stroke movement of the valve stem 8 and restricts its rotation.

[0042] The step motor 9 includes a stator 22 having a coil 21, and a magnet rotor 23 provided inside the stator 22. These components 21 to 23 are molded and covered by a resin casing 24. A connector 25 protruding laterally is formed on the casing 24. The connector 25 is provided with a terminal 26 extending from the coil 21.

[0043] The magnet rotor 23 includes a rotor body 27 and a cylindrical magnet 28 integrally provided on the outside of the rotor body 27. A first radial bearing 29 is provided on the outer periphery of the upper end of the rotor body 27, between the rotor body 27 and the casing 24. A second radial bearing 30 is provided on the inner periphery of the lower end of the magnet 28, between the magnet 28 and the thrust bearing 19. The first and second radial bearings 29, 30 rotatably support the magnet rotor 23 inside the stator 22. A female thread 31 is provided in the center of the rotor body 27, and is threaded onto the male thread 10 of the valve shaft 8. In this embodiment, the female thread 31 corresponds to an example of a "second screw" in the disclosed technology.

[0044] FIG. 3 is an enlarged cross-sectional view of a portion of the step motor 9 of the valve device 1 in the first open / close state. FIG. 4 is an enlarged cross-sectional view of a portion of the engagement between the male screw 10 and the female screw 31 in FIG. 3. FIG. 5 is an enlarged cross-sectional view of a portion of the step motor 9 of the valve device 1 in the second open / close state. FIG. 6 is an enlarged cross-sectional view of a portion of the engagement between the male screw 10 and the female screw 31 in FIG. 5. As shown in FIGS. 3 to 6, the male screw 10 has a male thread 10a that continues helically in the axial direction of the valve stem 8. This male thread 10a includes a first male thread surface 10aa facing (downward) toward the first valve seat 4 and a second male thread surface 10ab located on the opposite side (upper side) of the first male thread surface 10aa. The female screw 31 has a female thread 31a that continues helically in the axial direction of the valve stem 8. The female thread 31a includes a first female thread surface 31aa facing (downward) toward the first valve seat 4, and a second female thread surface 31ab located on the opposite side (upper side) of the first female thread surface 31aa. As shown in Figures 4 and 6, a predetermined backlash 35 (play) is provided between the male thread 10 and the female thread 31 in the axial direction of the valve stem 8.

[0045] Here, a valve element spring 32 is provided between the spring receiver 11 of the valve shaft 8 and the lower second radial bearing 30, i.e., between the spring receiver 11 and the housing 3, for urging the two valve elements 6, 7 together with the valve shaft 8 in a direction toward the step motor 9 (upward in Figures 1 to 6). The valve element spring 32 corresponds to an example of the "actuator spring" of the technology disclosed herein. In addition, a rotor spring 33 is provided between the magnet rotor 23 (magnet 28) and the second radial bearing 30, for urging the magnet rotor 23 in a direction away from the first valve seat 4.

[0046] A generally cylindrical lip seal 37 for sealing the gap between the housing 3 and the valve shaft 8 is provided adjacent to the thrust bearing 20 between the housing 3 and the valve shaft 8. A generally cylindrical deposit guard plug 38 for protecting the gap between the housing 3 and the valve shaft 8 from deposits is also provided adjacent to the lip seal 37 between the housing 3 and the valve shaft 8.

[0047] [About housing] 1 and 2, in this embodiment, the housing 3 is divided into a first housing portion 41 and a second housing portion 42 near the first valve seat 4, which is the closest of the two valve seats 4, 5 to the step motor 9. The first housing portion 41 and the second housing portion 42 each include a part of the flow path 2. By joining these two housing portions 41, 42, one housing 3 is formed, and the flow path 2 of the housing 3 is also formed.

[0048] [Valve device operation] 7 to 9 are schematic cross-sectional views showing the operating states of the first and second valve bodies 6, 7 and the valve stem 8 relative to the first and second valve seats 4, 5, as well as a portion of the associated housing 3 (first housing portion 41 and second housing portion 42). In this valve device 1, when the step motor 9 is driven to rotate the magnet rotor 23, the rotational motion is converted into stroke motion of the valve stem 8 and the two valve bodies 6, 7 via the female thread 31 and male thread 10, thereby adjusting the positions of the valve bodies 6, 7 relative to the two valve seats 4, 5.

[0049] That is, in this valve device 1, by rotating the magnet rotor 23 in one direction to stroke the valve shaft 8 together with the two valve discs 6 and 7 against the biasing force of the valve disc spring 32, the valve discs 6 and 7 move away from the step motor 9, resulting in the second open / close state shown in FIGS. 2 and 7. At this time, by controlling the step motor 9 so that the second valve disc 7 abuts against the second valve seat 5, the sealing surface 7a of the second valve disc 7 abuts against the seat portion 5a of the second valve seat 5, and the leading edge of the rubber sheet 18 is pressed against and deformed by the sealing surface 7a. In this abutting state, the second valve seat 5 functions as a valve-closing stopper for the second valve disc 7, restricting the rotation of the rotor body 27 and the stroke movement of the valve shaft 8 and the valve discs 6 and 7. The position of the valve shaft 8 at this time can be defined as its initial position.

[0050] In this abutting state, the step motor 9 may lose synchronization. When the step motor 9 loses synchronization, the biasing force of the valve spring 32 causes the valve elements 6 and 7 to move slightly toward the step motor 9, as shown in Figure 8, causing the second valve element 7 to open slightly. However, because the rubber sheet 18 is provided on the second valve seat 5, even if the second valve element 7 opens slightly, the tip of the rubber sheet 18 elastically contacts the sealing surface 7a of the second valve element 7, allowing the rubber sheet 18 to seal the gap between the second valve seat 4 and the second valve element 7.

[0051] At this time, the biasing force of the valve disc spring 32 causes the first female thread surface 31aa of the female thread 31 to engage with the second male thread surface 10ab of the male thread 10, as shown in FIG. 6. In this engaged state, the valve stem 8 is biased in a direction toward the step motor 9 (upward in FIG. 6) by the biasing force F1 (indicated by the black arrow) of the valve disc spring 32, so that the male thread 10a abuts against the female thread 31a without backlash 35, preventing the valve stem 8 from moving upward. Therefore, even if fluid pressure acts to pull or push the valve discs 6, 7 toward the step motor 9, the movement of the valve discs 6, 7 is prevented. This allows the valve discs 6, 7 to be maintained in the second open / closed state without increasing the output or size of the step motor 9 (actuator).

[0052] On the other hand, from this second open / close state, by rotating the magnet rotor 23 in the opposite direction, the valve shaft 8 strokes together with the two valve bodies 6, 7 in cooperation with the biasing force of the valve body spring 32, and the valve bodies 6, 7 move in a direction approaching the step motor 9, thereby entering the first open / close state shown in FIGS. 1 and 9. At this time, in the controlled fully closed state, when the seal surface 6a of the first valve body 6 abuts against the seat portion 4a of the first valve seat 4 and the magnet rotor 23 is further controlled to close the valve, the movement of the first valve body 6 is restricted by the first valve seat 4, so the second male thread surface 10ab separates from the first female thread surface 31aa, but the biasing force of the valve body spring 32 allows the valve to remain fully closed. Furthermore, the pressure of the fluid acting on the first valve body 6 also acts in the valve closing direction, so the valve can be maintained fully closed.

[0053] [About the manufacturing method of the valve device] Next, a portion of the manufacturing method of the valve device 1 will be described. Figures 10 to 12 are cross-sectional views showing some of the final stages of component assembly in the manufacturing method of the valve device 1. In this final stage of component assembly, two valve seats 4, 5 are provided in portions of the flow path 2 of each of the first housing portion 41 and the second housing portion 42. At this time, a rubber sheet 18 is provided on the second valve seat 5 in advance.

[0054] Thereafter, a process is carried out in which the step motor 9 is fixed to the first housing part 41, and one end 8a of the valve shaft 8, whose male thread 10 is threadably connected to the female thread 31 of the magnet rotor 23, is made to penetrate and protrude through the first valve seat 4 provided in the first housing part 41. In this process, the previously manufactured step motor 9 (including the valve shaft 8) and the first housing part 41 (including the first valve seat 4, the first flow path part 15, and the first outlet 13) are first assembled. At this time, the valve shaft 8 extending from the step motor 9 penetrates the bearings 19, 20, the lip seal 37, and the deposit guard plug 38 of the first housing part 41, and one end 8a thereof penetrates the first valve hole 4b of the first valve seat 4.

[0055] Thereafter, a step is carried out in which the two valve bodies 6, 7 are fixed to one end 8a of the valve stem 8 protruding from the first valve seat 4. In this step, as shown in Fig. 10, first, the first valve body 6 is inserted into one end 8a of the valve stem 8, and the valve body 6 is fixed to the valve stem 8 by welding 51 while seated on the first valve seat 4. Next, as shown in Fig. 11, the second valve body 7 is inserted into the end of one end 8a of the valve stem 8, and the valve body 7 is fixed to the valve stem 8 by welding 51.

[0056] After the valve elements 6 and 7 are fixed, as shown in Fig. 12, the two valve seats 4 and 5 are arranged coaxially in series, and the first housing part 41 and the second housing part 42 are joined together so that the two valve elements 6 and 7 are aligned with the corresponding valve seats 4 and 5. This completes the final stage of component assembly. Figs. 11 and 12 show weld marks 52 of the weld 51.

[0057] [About the function and effect of the valve device and its manufacturing method] According to the manufacturing method of the valve device 1 of this embodiment described above, after the two valve elements 6, 7 are fixed to one end 8a of the valve shaft 8 protruding into the flow path 2 of at least one of the first housing portion 41 and the second housing portion 42, the first housing portion 41 and the second housing portion 42 are joined so that the two valve seats 4, 5 are arranged coaxially in series and the two valve elements 6, 7 are aligned with the corresponding valve seats 4, 5. Therefore, it is possible to assemble the two valve elements 6, 7 onto the valve shaft 8 without being restricted by the flow path 2 of the housing 3 or the valve seats 4, 5. Therefore, for the valve device 1 having a multi-way poppet valve structure, the two valve elements 6, 7 corresponding to the two valve seats 4, 5 can be fixed to the single valve shaft 8 while ensuring a degree of freedom.

[0058] According to the configuration of the valve device 1 of this embodiment, the valve spring 32 biases the two valve elements 6, 7 together with the valve shaft 8 in a direction approaching the step motor 9. Therefore, the backlash 35 (play) between the male thread 10 of the valve shaft 8 and the female thread 31 of the rotor body 27, which are threadedly engaged with each other, is biased to one side, and the valve shaft 8 is coupled to the rotor body 27. Therefore, the valve elements 6, 7 can be fixed to the valve shaft 8 in a stable state.

[0059] According to the configuration of the valve device 1 of this embodiment, of the two valve bodies, the first valve body 6 is conical and has a tapered seal surface 6a on its outer periphery that can seat on the first valve seat 4, while the second valve body 7 is flat and has a flat seal surface 7a on its periphery that can seat on the second valve seat 5. Therefore, the centering requirement of the second valve body 7 relative to the second valve seat 5 is eased. That is, since the second valve body 7 is flat and its seal surface 7a is pressed against the seat portion 5a of the second valve seat 5, the centering requirement between the second valve body 7 and the second valve seat 5 is eased. As shown in FIG. 12 , even if there is a slight misalignment ΔC between the centers of the second valve body 7 and the second valve seat 5, sealing performance does not become a problem when the second valve body 7 is closed. Therefore, the coaxial accuracy of the valve bodies 6 and 7 relative to the valve stem 8 can be relaxed, which simplifies the manufacture of the valve device 1.

[0060] Furthermore, according to the configuration of the valve device 1 of this embodiment, the second valve element 7 is pressed against the second valve seat 5 via the rubber sheet 18, which reduces the perpendicularity of the second valve element 7 to the second valve seat 5. Therefore, even if the second valve element 7 is slightly tilted, the rubber sheet 18 can ensure sealing when the valve is closed. Furthermore, even if the step motor 9 loses synchronization and the second valve element 7 opens slightly, the rubber sheet 18 can ensure sealing.

[0061] Second Embodiment Next, a second embodiment will be described with reference to the drawings. In the following description, components equivalent to those in the first embodiment will be given the same reference numerals and will not be described again, and the following description will focus on the differences.

[0062] [About the manufacturing method of the valve device] This embodiment differs from the first embodiment in terms of the method of manufacturing the valve device. As a premise, the housing 3 of this embodiment is not divided into two pieces, but is formed as a whole in advance. FIGS. 13 to 15 are cross-sectional views showing some of the final steps of assembling parts in the method of manufacturing the valve device 1 of this embodiment. In this embodiment, as shown in FIGS. 13 to 15, the housing 3 has an assembly hole 3a in its flow path 2 that is used to assemble two valve bodies 6, 7 to the valve stem 8. This assembly hole 3a has a diameter larger than the diameter of at least the first valve body 6 that is assembled in a position closest to the step motor 9, and is provided so as to be able to hold the second valve seat 5.

[0063] In this embodiment, in the final stage of assembling parts, first, a step of providing the first valve seat 4 (a part of the valve seat) in the flow path 2 of the housing 3 is carried out.

[0064] Then, the step motor 9 is fixed to the housing 3, and one end 8a of the valve shaft 8, whose male thread 10 is threadedly connected to the female thread 31 by the magnet rotor 23, is made to penetrate and protrude through the first valve seat 4 provided in the housing 3.

[0065] Thereafter, a step is carried out in which the two valve bodies 6, 7 are fixed to one end 8a of the valve stem 8 protruding from the first valve seat 4 through the assembly holes 3a. In this step, first, as shown in Fig. 13, the first valve body 6 is inserted into one end 8a of the valve stem 8, and the valve body 6 is fixed to the valve stem 8 by welding 51 while seated on the first valve seat 4. Next, as shown in Fig. 14, the second valve body 7 is inserted into the end of one end 8a of the valve stem 8, and the valve body 7 is fixed to the valve stem 8 by welding 51.

[0066] Then, after the two valve bodies 6, 7 are fixed, a process is carried out in which the second valve seat 5 (the remaining valve seat) is assembled into the assembly hole 3a. In this process, as shown in Figures 14 and 15, the second valve seat 5 provided with the rubber sheet 18 is press-fitted into the assembly hole 3a, and the second valve seat 5 is held down by the flange 53a of the pipe 53 communicating with the flow path 2 to prevent it from coming off the housing 3. In this way, the final stage of assembly is completed.

[0067] [About the function and effect of the valve device and its manufacturing method] According to the manufacturing method of the valve device 1 of this embodiment described above, the two valve elements 6, 7 are fixed via the assembly hole 3a to one end 8a of the valve shaft 8 protruding into the flow path 2 of the housing 3, and then one valve seat 5 is assembled into the assembly hole 3a. Therefore, it is possible to assemble the two valve elements 6, 7 onto the valve shaft 8 without dividing the housing 3 and without being restricted by the flow path 2 or the valve seats 4, 5. For this reason, in the valve device 1 having a multi-way poppet valve structure, the two valve elements 6, 7 corresponding to the two valve seats 4, 5 can be fixed to one valve shaft 8 while ensuring a degree of freedom.

[0068] The functions and effects of the valve device 1 of this embodiment are the same as those of the first embodiment.

[0069] <Third embodiment> Next, a third embodiment will be described with reference to the drawings.

[0070] [About the manufacturing method of the valve device] This embodiment differs from the second embodiment in the configuration of the method for manufacturing the valve device 1. Figures 16 to 18 are cross-sectional views showing some of the final assembly steps in the method for manufacturing the valve device 1 of this embodiment.

[0071] This embodiment further includes a step of previously forming the two valve bodies 6, 7 into an integral assembled valve body 44. This assembled valve body 44 is formed by fixing the first valve body 6 and the second valve body 7 to both ends of a pipe material 45 through which the valve stem 8 is inserted, thereby assembling the two valve bodies 6, 7 together.

[0072] In the final stage of assembling the parts, first, a step of providing the first valve seat 4 (a part of the valve seat) in the flow path 2 of the housing 3 is carried out.

[0073] Then, the step motor 9 is fixed to the housing 3, and one end 8a of the valve shaft 8, whose male thread 10 is threadedly connected to the female thread 31 by the magnet rotor 23, is made to penetrate and protrude through the first valve seat 4 provided in the housing 3.

[0074] Thereafter, a process is carried out in which the two valve bodies 6, 7 are fixed to one end 8a of the valve shaft 8 protruding from the first valve seat 4. In this process, first, as shown in Fig. 16, the assembled valve body 44 is assembled to one end 8a of the valve shaft 8, and after this assembly, as shown in Fig. 17, the assembled valve body 44 is fixed to the valve shaft 8 at the end of one end 8a of the valve shaft 8 by welding 51.

[0075] Thereafter, a step of assembling the second valve seat 5 into the assembly hole 3a is carried out. In this step, as shown in Fig. 18, the second valve seat 5 provided with the rubber sheet 18 is press-fitted into the assembly hole 3a, and the second valve seat 5 is held down by the flange 53a of the pipe 53 communicating with the flow path 2 to prevent it from coming off the housing 3. In this way, the final stage of assembly is completed.

[0076] [Operation and effect of the valve device manufacturing method] According to the configuration of the manufacturing method of the valve device 1 of this embodiment described above, in the step of fixing the two valve bodies 6, 7, the assembled valve body 44 is assembled to one end side 8a of the valve shaft 8, and then the assembled valve body 44 is fixed to the valve shaft 8 at the end of one end side 8a of the valve shaft 8. This requires fewer steps than fixing the two valve bodies 6, 7 individually to the valve shaft 8. Therefore, the manufacturing of the valve device 1 can be simplified by the reduced number of steps.

[0077] The functions and effects of the valve device 1 of this embodiment are the same as those of the second embodiment.

[0078] <Fourth embodiment> Next, a fourth embodiment will be described with reference to the drawings.

[0079] [Valve device configuration] In this embodiment, the valve device 1 differs from the first embodiment in the configuration of the first valve seat 4 and the first valve body 6. FIGS. 19 to 21 are cross-sectional views schematically illustrating the operation of the first and second valve bodies 6, 7 and the valve stem 8 relative to the first and second valve seats 4, 5, as well as a portion of the associated housing 3 (the first housing portion 41 and the second housing portion 42). In this embodiment, rubber sheets 48, 18 are provided on both the first and second valve seats 4, 5. Furthermore, both the first and second valve bodies 6, 7 are flat. That is, like the second valve body 7, the first valve body 6 is also flat and has a flat sealing surface 6a on its periphery, which is capable of seating on the flat seat portion 4a of the first valve seat 4. However, in this embodiment, the thickness and displacement amount L2 (see Figure 21) of the rubber sheet 48 provided on the second valve seat 5 are set larger than the thickness and displacement amount L1 (see Figure 19) of the rubber sheet 48 provided on the first valve seat 4.

[0080] [Valve device operation] According to the configuration of the valve device 1 of this embodiment, when the leakage requirements between the first valve seat 4 and the first valve body 6 and between the second valve seat 5 and the second valve body 7 are both strict, the rubber sheets 48, 18 provided on both valve seats 4, 5 act effectively in terms of sealing properties.

[0081] 19, when the two valve bodies 6, 7 are in the second open / closed state, the sealing surface 7a of the second valve body 7 abuts against the seat portion 5a of the second valve seat 5, and the tip of the rubber sheet 18 presses against and deforms against the sealing surface 7a. If the step motor 9 loses synchronization in this abutting state, the valve bodies 6, 7 move slightly toward the step motor 9, as shown in FIG. 20, causing the second valve body 7 to slightly open. At this time, the tip of the rubber sheet 18 elastically contacts the sealing surface 7a of the second valve body 7, allowing the rubber sheet 18 to seal the gap between the second valve seat 4 and the second valve body 7. In other words, after synchronization loss occurs, the second valve body 7 is not in contact with the second valve seat 5, but the rubber sheet 18 is in contact with the second valve body 7.

[0082] 21 , when the two valve bodies 6, 7 are in the first open / close state, the sealing surface 6a of the first valve body 6 abuts against the seat portion 4a of the first valve seat 4, and the rubber sheet 48 presses against the sealing surface 6a. Even if the step motor 9 loses synchronization in this abutting state, the biasing force of the valve body spring 32 urges the valve bodies 6, 7 in a direction approaching the step motor 9, so the first open / close state can be maintained with the first valve body 6 abutting against the first valve seat 4. In other words, after a loss of synchronization occurs, the first valve body 6 comes into contact with the first valve seat 4, and the rubber sheet 48 also comes into contact with the first valve body 6.

[0083] Fifth Embodiment Next, a fifth embodiment will be described with reference to the drawings.

[0084] [Valve device configuration] This embodiment differs from the first embodiment in that a flow path spring 46 is further provided around the valve stem 8 in the flow path 2 of the valve device 1, a rubber sheet 48 is provided on the first valve seat 4, and the rubber sheet 18 is not provided on the second valve seat 5. Fig. 22 shows the second open / close state of the valve device 1 in a cross-sectional view equivalent to Fig. 7. Fig. 23 shows the first open / close state of the valve device 1 in a cross-sectional view equivalent to Fig. 9. As shown in Figs. 22 and 23, of the two valve bodies 6, 7 on the valve stem 8, the first valve body 6 closest to the step motor 9 is disposed in the flow path 2 (second flow path section 16) opposite the flow path 2 (first flow path section 15) closest to the step motor 9, with the corresponding first valve seat 4 as the boundary. A flow path spring 46 is provided on the valve shaft 8 between the first valve body 6 and the inner wall 15a of the flow path 2 (first flow path section 15) closest to the step motor 9 and adjacent to the corresponding first valve seat 4, to urge the two valve bodies 6, 7 together with the valve shaft 8 in a direction away from the step motor 9 in order to urge the second valve body 7 in a direction to seat it on the corresponding second valve seat 5. Here, the urging force F2 (indicated by the white arrow) of the flow path spring 46 is set larger than the urging force F1 (indicated by the white arrow) of the valve body spring 32 of the step motor 9.

[0085] [Valve device operation] 22, when the two valve bodies 6, 7 are in the second open / close state, even if the second valve body 7 abuts against the second valve seat 5 and the step motor 9 loses synchronization, the second valve body 7 is pressed against the second valve seat 5 by the biasing force F2 of the flow path spring 46. Therefore, the second valve body 7 can be maintained in a closed state relative to the second valve seat 5, i.e., the second open / close state.

[0086] 23, when the two valve bodies 6, 7 are in the first open / close state, if the first valve body 6 hits the first valve seat 4 and the step motor 9 loses synchronization, the valve will open slightly due to the biasing force F2 of the flow path spring 46. Therefore, by providing a rubber sheet 48 on the first valve seat 4, sealing performance can be ensured even if the valve opens slightly.

[0087] [About the function and effect of the valve device] According to the configuration of the valve device 1 of this embodiment described above, unlike the first embodiment, a flow path spring 46 is provided on the valve stem 8 between the first valve disc 6, which is closest to the step motor 9, and the inner wall 15a of the flow path 2 (first flow path portion 15) closest to the step motor 9 and adjacent to the corresponding first valve seat 4. The flow path spring 46 urges the two valve discs 6, 7 together with the valve stem 8 in a direction away from the step motor 9, thereby urging the farthest second valve disc 7 in a direction to seat it on the corresponding second valve seat 5. Therefore, when the valve discs 6, 7 are assembled to the valve stem 8, the valve discs 6, 7 can be assembled in a stable position. This allows the valve device 1 to improve the adhesion and sealing performance of the valve discs 6, 7 when fully closed.

[0088] Sixth Embodiment Next, a sixth embodiment will be described with reference to the drawings.

[0089] [Valve device configuration] This embodiment differs from the fifth embodiment in the configuration of the first valve seat 4 and the second valve seat 5, the position of the first valve element 6 relative to the first valve seat 4, and the position of the second valve element 7 relative to the second valve seat 5. Furthermore, in this embodiment, a rubber sheet 18 is provided on the second valve seat 5. In the fifth embodiment, a flow path spring 46 is provided on the valve stem 8. When both valve elements 6 and 7 are in the second open / closed state, i.e., when the first valve element 6 is open and the second valve element 7 is closed, the flow path spring 46 may increase the pressure loss of the fluid flowing through the first valve hole 4b. In this embodiment, the positions of the valve elements 6 and 7 are changed to solve this problem. Figure 24 shows the first open / closed state of the valve device 1 in a cross-sectional view similar to Figure 23. Figure 25 shows the second open / closed state of the valve device 1 in a cross-sectional view similar to Figure 22. As shown in FIGS. 24 and 25 , in this embodiment, the first valve element 6 is disposed in the flow path 2 (first flow path section 15) closest to the step motor 9 across the corresponding first valve seat 4. The second valve element 7 in this embodiment is disposed in the flow path 2 (third flow path section 17) opposite the flow path 2 (second flow path section 16) closest to the step motor 9 across the corresponding second valve seat 5. A flow path spring 46 is provided on the valve shaft 8 between the first valve element 6 and the inner wall 15a of the first flow path section 15 opposite the corresponding first valve seat 4. The flow path spring 46 biases the two valve elements 6, 7 together with the valve shaft 8 in a direction away from the step motor 9 to bias the first valve element 6 in a direction to seat it on the corresponding first valve seat 4. The biasing force F2 of the flow path spring 46 is set to be greater than the biasing force F1 of the valve element spring 32 of the step motor 9.

[0090] [Valve device operation] 24, when the two valve bodies 6, 7 are in the first open / close state, even if the first valve body 6 abuts against the first valve seat 4 and the step motor 9 loses synchronization, the first valve body 6 is pressed against the first valve seat 4 by the biasing force F2 of the flow path spring 46. Therefore, the closed state of the first valve body 6 relative to the first valve seat 4, i.e., the first open / close state, can be maintained.

[0091] 25, when the two valve bodies 6, 7 are in the second open / close state, if the second valve body 7 hits the second valve seat 5 and the step motor 9 loses synchronization, the valve will open slightly due to the biasing force F2 of the flow path spring 46. Therefore, by providing a rubber sheet 18 on the second valve seat 5, sealing performance can be ensured even if the valve opens slightly.

[0092] [About the function and effect of the valve device] According to the configuration of the valve device 1 of this embodiment described above, unlike the fifth embodiment, the arrangement of the first valve body 6 relative to the first valve seat 4 and the arrangement of the second valve body 7 relative to the second valve seat 5 are changed, and a flow path spring 46 is provided on the valve shaft 8 between the first valve body 6 and the inner wall 15a of the first flow path portion 15, as shown in Figures 24 and 25. Therefore, when both valve bodies 6, 7 are in the second open / close state, that is, when the first valve body 6 is open and the second valve body 7 is closed, the flow path spring 46 does not obstruct the fluid flowing through the first valve hole 4b of the first valve seat 4. This makes it possible to prevent an increase in pressure loss of the fluid when both valve bodies 6, 7 are in the second open / close state.

[0093] Seventh Embodiment Next, a seventh embodiment will be described with reference to the drawings.

[0094] This embodiment differs from the first to fourth embodiments mainly in the configurations of the second valve seat 5 and the second valve body 7. FIGS. 26 and 27 show cross-sectional views of only the second valve seat 5 and the second valve body 7 of this embodiment. As shown in FIGS. 26 and 27, the second valve seat 5 of this embodiment has a truncated cone shape. Furthermore, the rubber sheet 18 provided on the second valve seat 5 has a lip shape that matches the shape of the second valve body 7, making it easier to come into contact with the tapered sealing surface 7a of the second valve body 7.

[0095] [About the function and effect of the valve device] According to the configuration of the valve device 1 of this embodiment described above, when the second valve body 7 abuts against the second valve seat 5 and closes the valve, the rubber sheet 18 also presses against the sealing surface 7a, improving sealing performance, as shown in Fig. 26. On the other hand, even if the second valve body 7 abuts against the second valve seat 5, causing the step motor 9 to lose synchronization and creating a gap between the second valve body 7 and the second valve seat 5, sealing performance can be ensured by the contact between the second valve body 7 and the rubber sheet 18, as shown in Fig. 27.

[0096] Eighth Embodiment Next, an eighth embodiment will be described with reference to the drawings.

[0097] [Valve device configuration] In this embodiment, the valve device 1 differs from the first embodiment in the configuration of the second valve seat 5 and the second valve body 7. Figures 28 and 29 are cross-sectional views showing the second open / close state of the valve device 1. Figure 30 is a cross-sectional view showing the first open / close state of the valve device 1. As shown in Figures 28 to 30, in this embodiment, the second valve seat 5 is not provided with a rubber sheet 18. Also, the second valve body 7 has a truncated cone shape like the first valve body 6.

[0098] [Configuration of the water flow switching device] FIG. 31 is a schematic diagram showing the configuration of a water flow switching device including a valve device 1. As shown in FIG. 31, in addition to the valve device 1, this water flow switching device also includes an electric water pump 61 and an electronic control unit (ECU) 62. To switch the water flow path, an inlet pipe 56 is connected to the inlet 12 of the valve device 1, a first outlet pipe 57 is connected to the first outlet 13, and a second outlet pipe 58 is connected to the second outlet 14. The water pump 61 is provided on the inlet pipe 56. The ECU 62 is electrically connected to the step motor 9 of the valve device 1 and the water pump 61 to control them. The ECU 62 also determines an abnormality in the coil 21 of the step motor 9 of the valve device 1 based on the control state of the step motor 9.

[0099] FIG. 28 shows a case where the ECU 62 turns on (energizes) the valve device 1 and the water pump 61 and the coil 21 is abnormal. FIG. 29 shows a case where, from the state shown in FIG. 28, the ECU 62 turns off (de-energizes) the water pump 61. FIG. 30 shows a case where, from the state shown in FIG. 29, the ECU 62 turns off the valve device 1 and turns the water pump 61 back on. In this embodiment, the lead angle of the male thread 10 and the female thread 31 in the step motor 9 of the valve device 1 is assumed to be steep (large), so that the biasing force of the valve element spring 32 returns the first valve element 6 and the second valve element 7 to their initial positions, the first open / closed state. In this embodiment, if the coil 21 is abnormal when the valve device 1 is in the second open / closed state as shown in FIG. 28, the pressure of the water pumped from the water pump 61 to the valve device 1 presses the second valve element 7 against the second valve seat 5. In this case, the water pressure F3 acts in a direction that opposes the action of returning both valve elements 6, 7 to the first open / closed state, which may prevent both valve elements 6, 7 from returning to the first open / closed state. Therefore, in this embodiment, the ECU 62 executes the following coil abnormality control.

[0100] [Control in the event of a coil abnormality] Figure 32 is a flowchart showing the contents of the control when a coil abnormality occurs. When the ECU 62 shifts processing to this routine, it determines in step 100 whether or not there is a coil abnormality. For example, if the step motor 9 does not operate even when the coil 21 is energized, the ECU 62 electrically detects this and determines that there is a coil abnormality. If the result of this determination is positive, the ECU 62 shifts processing to step 110, and if the result of this determination is negative, the ECU 62 shifts processing to step 170.

[0101] In step 110, the ECU 62 determines whether the second valve body 7 is closed. If the result of this determination is positive, the ECU 62 proceeds to step 120, and if the result of this determination is negative, the ECU 62 proceeds to step 180.

[0102] In step 120, the ECU 62 determines whether the coil abnormality processing flag XCF is "0." As will be described later, the ECU 62 sets this flag XCF to "1" or "0." If the result of this determination is positive, the ECU 62 proceeds to step 130, and if the result of this determination is negative, the ECU 62 proceeds to step 180.

[0103] In step 130, the ECU 62 stops (turns off) the water pump 61. In this case, the pressure acting on both valve bodies 6, 7 changes from the state shown in Fig. 28 to the state shown in Fig. 29. That is, in this case, as shown in Fig. 29, the water pressure F3 pressing the second valve body 7 against the second valve seat 5 is no longer acting on the second valve body 7, and the biasing force F1 of the valve body spring 32 that moves both valve bodies 6, 7 closer to the step motor 9 acts on both valve bodies 6, 7, and both valve bodies 6, 7 return from the state shown in Fig. 29 to the first open / close state shown in Fig. 30.

[0104] Next, in step 140, the ECU 62 determines whether a predetermined time A1 has elapsed since the water pump was stopped. If the result of this determination is positive, the ECU 62 proceeds to step 150, and if the result of this determination is negative, the ECU 62 returns to step 100.

[0105] In step 150, the ECU 62 sets the coil abnormality processing flag XCF to "1."

[0106] Next, in step 160, the ECU 62 restores the operation of the water pump 61. That is, the water pump 61 is turned on again. Thereafter, the ECU 62 returns the process to step 100. In this case, as shown in FIG. 30, a water pressure F3 acts on the first valve body 6, pressing it against the first valve seat 4, and both valve bodies 6, 7 are maintained in the first open / close state (initial position).

[0107] On the other hand, moving from step 100 to step 170, the ECU 62 sets the coil abnormality processing flag XCF to "0".

[0108] Next, in step 180, the ECU 62 continues the operation of the water pump 61. That is, the ECU 62 keeps the water pump 61 on. Thereafter, the ECU 62 returns the process to step 100.

[0109] According to the coil abnormality control described above, when both valve bodies 6, 7 are in the second open / close state due to a coil abnormality, the ECU 62 stops the water pump 61 to release the water pressure acting on the second valve body 7. This makes it easier for both valve bodies 6, 7 to return to the initial position, that is, the first open / close state, by the biasing force of the valve body spring 32.

[0110] Ninth Embodiment Next, a ninth embodiment will be described with reference to the drawings.

[0111] [Configuration of valve device and water flow switching device] The valve device 1 and water flow switching device of this embodiment are basically similar in configuration to those of the eighth embodiment. However, in this embodiment, the lead angles of the male thread 10 and the female thread 31 of the step motor 9 are flat (small), so that the positions of the first valve element 6 and the second valve element 7 can be maintained even when the power supply to the coil 21 is stopped. Furthermore, since the valve device 1 of this embodiment does not have a sensor for detecting the opening positions of the valve elements 6 and 7, the ECU 62 uses the number of control steps, which is a command value for controlling the step motor 9, as the opening positions of the valve elements 6 and 7 for control purposes. However, if the power supply to the coil 21 is interrupted for some reason while the step motor 9 is operating, the opening positions of the valve elements 6 and 7 become unknown, making it difficult to perform abnormality control based on the opening positions of the valve elements 6 and 7. Therefore, in this embodiment, the ECU 62 executes the following valve opening position storage control.

[0112] [Valve opening position memory control] Figure 33 is a flowchart showing the contents of the valve opening position storage control. When the ECU 62 shifts the processing to this routine, it determines in step 200 whether the coil is normal. For example, when the coil 21 is energized to operate the step motor 9, the ECU 62 electrically detects this and determines that the coil is normal. If the result of this determination is positive, the ECU 62 shifts the processing to step 210, and if the result of this determination is negative, the ECU 62 shifts the processing to step 230.

[0113] In step 210, the ECU 62 acquires the current (current) number of control steps for the step motor 9 in the normal state.

[0114] Next, in step 220, the ECU 62 stores the number of control steps in a normal state in memory, and returns the process to step 200.

[0115] On the other hand, in step 230 following step 200, the ECU 62 acquires the current (at that time) number of control steps for the step motor 9 in the abnormal state.

[0116] Next, in step 240, the ECU 62 stores the number of control steps in the abnormal state in the memory, and returns the process to step 200.

[0117] According to the valve opening position storage control described above, the ECU 62 always stores the current control step number, and keeps the step number stored even when the power is off. This allows the ECU 62 to confirm the open / closed positions of the valve elements 6, 7 based on the stored control step number even if the power supply to the coil 21 is cut off. Therefore, the ECU 62 can execute abnormality control according to the open / closed positions of the valve elements 6, 7 even when a coil abnormality occurs.

[0118] Tenth Embodiment Next, a tenth embodiment will be described with reference to the drawings.

[0119] [Valve device configuration] This embodiment differs from the previous embodiments in the configurations of the housing 3, flow path 2, valve seat 74, and valve disc 76. Figures 34 and 35 show cross-sectional views of a valve device 71 of this embodiment. The valve device 71 of this embodiment has a configuration equivalent to that of the valve device 1 of the previous embodiments with respect to the step motor 9. A single valve seat 74 having a valve hole 74a with a large inner diameter is provided in the flow path 2 of the housing 3. A single valve disc 76 with a large outer diameter is provided on the valve shaft 8 corresponding to the valve seat 74. The valve disc 76 has a truncated cone shape and a tapered sealing surface 76a on its outer periphery. The flow path 2 of this embodiment is divided by the valve seat 74 into an upstream flow path 2A (shown below in the figure) and a downstream flow path 2B (shown above in the figure). The valve disc 76 is positioned in the downstream flow path 2B so that it can seat on the valve seat 74. In the downstream flow path 2B, a flow path spring 77 is provided between the valve element 76 and the flow path inner wall 2Ba opposite the valve seat 74, surrounding the valve stem 8. The flow path spring 77 biases the valve element 76 in the direction of seating on the valve seat 74. In this embodiment, the biasing force of the flow path spring 77 is set to be greater than the biasing force of the valve element spring 32 provided in the step motor 9.

[0120] [Valve device operation] 34, even if the valve element 76 hits the valve seat 74 and the step motor 9 loses synchronization, the valve element 76 is pressed against the valve seat 74 by the biasing force of the flow path spring 77. Here, even if the power supply to the coil 21 of the step motor 9 is stopped, the valve element 76 is pressed against the valve seat 74 by the biasing force of the flow path spring 77. Therefore, the valve element 76 can be maintained in a closed state relative to the valve seat 74.

[0121] 35, when the coil 21 of the step motor 9 is energized to open the valve element 76, the valve element 76 opens against the biasing force of the flow path spring 77. At this time, the flow path spring 77 contracts between the valve element 76 and the flow path inner wall 2Ba, but since it is not exposed between the valve seat 74 and the valve element 76, the flow path spring 77 does not cause pressure loss in the fluid flow.

[0122] Eleventh Embodiment Next, an eleventh embodiment will be described with reference to the drawings.

[0123] [Valve device configuration] This embodiment differs from the tenth embodiment mainly in the configurations of the valve seat 74 and the valve element 76. Figures 36 and 37 show cross-sectional views of a valve device 71 of this embodiment. That is, the valve element 76 of the valve device 71 of this embodiment is disk-shaped, and the lower peripheral edge thereof forms a sealing surface 76a that can come into contact with a seat portion 74b of the valve seat 74. In addition, an annular rubber sheet 78 is provided on the seat portion 74b of the valve seat 74 so as to be able to come into contact with the sealing surface 76a of the valve element 76. In this embodiment, the biasing force of the flow path spring 77 is set to be greater than the biasing force of the valve element spring 32 of the step motor 9 but smaller than the biasing force of the rotor spring 33.

[0124] [Valve device operation] 36, even if the valve element 76 hits the valve seat 74 and the step motor 9 loses synchronization, the valve element 76 is pressed against the valve seat 74 by the biasing force of the flow path spring 77. Even if the power supply to the coil 21 of the step motor 9 is stopped, the valve element 76 is pressed against the valve seat 74 by the biasing force of the flow path spring 77. Therefore, as in the tenth embodiment, the valve element 76 can be maintained in a closed state relative to the valve seat 74.

[0125] On the other hand, because the outer diameter of the valve disc 76 is large, fluid pressure from the upstream flow path 2A acts on the valve disc 76. If this pressure overcomes the biasing force of the flow path spring 77, the valve disc 76 may be pushed up from the valve seat 74, causing the valve to open. However, in this embodiment, the rubber sheet 78 is provided. As shown in FIG. 37, even if the valve disc 76 opens slightly, sealing performance can be maintained as long as the rubber sheet 78 is in contact with the sealing surface 76a of the valve disc 76. Here, as shown in FIG. 36, even if the step motor 9 loses synchronization when the valve disc 76 abuts against the valve seat 74, the male thread 10 contacts the female thread 31 at a maximum valve open position of four steps of the step motor 9, restricting movement of the valve stem 8, i.e., the opening of the valve disc 76. Therefore, by adjusting the rubber sheet 78's ability to follow the deformation of the valve disc 76 to match the four steps, the valve disc 76's fully closed sealing performance can be maintained.

[0126] <Another embodiment> The disclosed technology is not limited to the above-described embodiments, and can be implemented by appropriately modifying part of the configuration within the scope of the disclosed technology.

[0127] 38 , the housing 3 is divided into a first housing portion 41 and a second housing portion 42 near the first valve seat 4, which is the closest of the two valve seats 4, 5 to the step motor 9, and the flow path 2 of the housing 3 is composed of a first flow path portion 15 that is closest to the step motor 9 across the first valve seat 4, a second flow path portion 16 between the first valve seat 4 and the second valve seat 5, and a third flow path portion 17 that is farthest from the step motor 9 across the second valve seat 5. The first valve element 6 and the second valve element 7 are fixed to one end 8a of the valve shaft 8 that protrudes into the second flow path portion 16 of the second housing portion 42, and then the first housing portion 41 and the second housing portion 42 are joined together so that the two valve seats 4, 5 are arranged coaxially in series and the two valve elements 6, 7 are aligned with the corresponding valve seats 4, 5. 39, the housing 3 of the valve device 1 can be similarly divided into two housing portions 41, 42, and the flow path 2 can be composed of first to third flow path portions 15-17. One end 8a of the valve shaft 8 can be protruded into all of the flow path portions 15-17 of the two housing portions 41, 42, and the first valve element 6 can be fixed to the one end 8a in the first flow path portion 15. Then, the two housing portions 41, 42 can be joined so that the two valve seats 4, 5 are arranged coaxially in series and the two valve elements 6, 7 are aligned with the corresponding valve seats 4, 5, and the second valve element 7 can be fixed to the one end 8a in the third flow path portion 17. FIGS. 38 and 39 are schematic diagrams showing the configuration of the valve device 1, each showing the housing 3 and the valve seats 4, 5 in cross section.

[0128] (2) In the first embodiment, the valve device 1 is configured as shown in FIG. 38 . However, as shown in FIG. 40 , the housing 3 constituting a valve device 81 having a two-way poppet valve structure may be divided into a first housing portion 41 and a second housing portion 42, and the flow path 2 may be configured with a first flow path portion 15 close to the step motor 9 and a second flow path portion 16 on the opposite side of the first valve seat 4. The first valve element 6 may be fixed to one end 8a of the valve shaft 8 protruding into the first flow path portion 15 of the first housing portion 41, and then the first housing portion 41 and the second housing portion 42 may be joined together so that the valve element 6 is aligned with the valve seat 4. In this case, the valve element 6 is fixed to one end 8a of the valve shaft 8 protruding into the flow path 2 (first flow path portion 15) of the first housing portion 41, and then the first housing portion 41 and the second housing portion 42 may be joined together so that the valve element 6 is aligned with the valve seat 4. Therefore, it is possible to assemble the valve element 6 onto the valve shaft 8 without being restricted by the flow path 2 or valve seat 4 of the housing 3. As a result, for a valve device 81 having a two-way poppet valve structure, the valve element 6 can be fixed to one valve shaft 8 while ensuring a degree of freedom. Figure 40 is a schematic diagram showing the configuration of a valve device 81 having a two-way poppet valve structure, and only the housing 3 and valve seat 4 are shown in cross section.

[0129] (3) In the valve device 1 of the second embodiment, as shown in Fig. 41, the flow path 2 provided in one housing 3 is divided into a side closer to the step motor 9 and a side farther from the step motor 9, with the two valve seats 4, 5 as boundaries, and an assembly hole 3a having a diameter larger than the diameters of the two valve bodies 6, 7 and capable of holding the second valve seat 5 is provided corresponding to the second and third flow path sections 16, 17 of the housing 3. Then, the first valve seat 4 is provided in the second flow path section 16 of the housing 3, and the two valve bodies 6, 7 are fixed via the assembly hole 3a to one end side 8a of the valve shaft 8 that protrudes into the second flow path section 16 via the first valve seat 4, and then the remaining second valve seat 5 is assembled into the assembly hole 3a. 42, the flow path 2 provided in one housing 3 is divided into a side closer to the step motor 9 and a side farther from the step motor 9, with each of the two valve seats 4, 5 as boundaries. An assembly hole 3b capable of holding the first valve seat 4 and an assembly hole 3a capable of holding the second valve seat 5 are provided corresponding to all flow path sections 15-17 of the housing 3, each having a diameter larger than that of the two valve bodies 6, 7. The first valve body 6 can be fixed to one end 8a of the valve shaft 8 protruding into all flow path sections 15-17 of the housing 3 via the assembly holes 3a, 3b in the first flow path section 15, the first valve seat 4 can be assembled into the assembly hole 3b, and the remaining second valve seat 5 can be assembled into the assembly hole 3a. Finally, the second valve body 7 can be fixed in the third flow path section 17. FIGS. 41 and 42 are schematic diagrams showing the configuration of the valve device 1, each showing a cross section of the housing 3 and the valve seats 4, 5.

[0130] (4) In the second embodiment, the valve device 1 was configured as shown in Fig. 41 . However, as shown in Fig. 43 , the flow path 2 of the housing 3 constituting a valve device 82 having a two-way poppet valve structure is configured with a first flow path section 15 close to the step motor 9 and a second flow path section 16 on the opposite side of the first valve seat 4, with the housing 3 provided with an assembly hole 3a that has a diameter larger than the diameter of the first valve element 6 assembled to the valve stem 8 in the first flow path section 15 and is capable of holding the first valve seat 4. The first valve element 6 can then be fixed via the assembly hole 3a to one end 8a of the valve stem 8 protruding into the first flow path section 15 of the housing 3, and then the first valve seat 4 can be assembled into the assembly hole 3a. Fig. 43 is a schematic diagram showing the configuration of the valve device 82, showing only the housing 3 and the valve seat 4 in cross section.

[0131] (5) In each of the above embodiments, the first screw provided on the valve shaft 8 is configured as a male screw 10, and the second screw provided on the rotor body 27 is configured as a female screw 31. However, the first screw may be configured as a female screw, and the second screw may be configured as a male screw that is screwed into the female screw.

[0132] (6) In each of the above embodiments, two valve seats 4, 5 and two valve bodies 6, 7 are provided as multiple valve seats and multiple corresponding valve bodies, but three or more valve seats and three or more corresponding valve bodies may also be provided. [Industrial Applicability]

[0133] The disclosed technology can be applied to a valve device that has a poppet valve structure and controls the flow of a fluid. [Explanation of symbols]

[0134] 1 Valve gear 2 Flow path 3. Housing 3a Assembly hole 3b Assembly hole 4 First valve seat 5 Second valve seat 6 First valve body 6a sealing surface 7 Second valve body 7a sealing surface 8 Valve stem 8a One end side 8b Other end side 9 Step motor (actuator) 10 Male thread (first thread) 12 Inlet 13 1st outlet 14 2nd outlet 15 First flow path section 15a Inner wall 16 Second flow path section 17 Third flow path section 23 Magnet rotor 31 Female thread (second thread) 32 Valve spring (actuator spring) 41 First housing section 42 Second housing section 44 Valve assembly 46 Flow path spring 71 Valve gear 81 Valve gear 82 Valve gear

Claims

1. a housing having a fluid flow path; a plurality of valve seats arranged in series on the same axis in the flow path; a plurality of valve bodies each capable of being seated on the valve seats; a valve shaft on which a plurality of the valve bodies are coaxially arranged in series; the valve shaft includes one end side and the other end side, the plurality of valve bodies are fixed to the one end side, and a first screw is provided to the other end side; an actuator for reciprocating the valve stem in its axial direction; the actuator includes a rotor having a second thread that is threadably engaged with the first thread; The flow path is divided into a side closer to the actuator and a side farther from the actuator with each of the valve seats as a boundary, and the corresponding valve element is arranged on the side closer to the actuator or the side farther from the actuator so as to be able to seat on the valve seat. A method for manufacturing a valve device comprising: the housing is divided into a first housing portion and a second housing portion near the valve seat closest to the actuator among the plurality of valve seats, and the first housing portion and the second housing portion each include a part of the flow path; a step of fixing the plurality of valve bodies to the one end side of the valve stem that protrudes into the flow path of at least one of the first housing portion and the second housing portion; a step of joining the first housing part and the second housing part together so that, after the valve bodies are fixed, the valve seats are arranged in series on the same axis and the valve bodies are aligned with the corresponding valve seats; A method for manufacturing a valve device, comprising:

2. a housing having a fluid flow path; a plurality of valve seats arranged in series on the same axis in the flow path; a plurality of valve bodies each provided to be seated on a corresponding one of the plurality of valve seats; a valve shaft on which a plurality of the valve bodies are coaxially arranged in series; the valve shaft includes one end side and the other end side, the plurality of valve bodies are fixed to the one end side, and a first screw is provided to the other end side; an actuator for reciprocating the valve stem in its axial direction; the actuator includes a rotor having a second thread that is threadably engaged with the first thread; The flow path is divided into a side closer to the actuator and a side farther from the actuator with each of the valve seats as a boundary, and the corresponding valve element is arranged on the side closer to the actuator or the side farther from the actuator so as to be able to seat on the valve seat. A method for manufacturing a valve device comprising: the housing includes an assembly hole in the flow path, the assembly hole having a diameter larger than a diameter of the valve element assembled at least at a position closest to the actuator and capable of holding the valve seat; a step of fixing at least one of the valve bodies to the one end side of the valve stem protruding into the flow path of the housing through the assembly hole; a step of assembling at least one of the valve seats into the assembly hole after the valve body is fixed; A method for manufacturing a valve device, comprising:

3. 3. The method for manufacturing a valve device according to claim 1 or 2, Further provided is an assembled valve body in which a plurality of the valve bodies are integrally assembled, In the step of fixing the plurality of valve bodies, the assembled valve body is assembled to the one end side of the valve shaft, and after the assembly, the assembled valve body is fixed to the valve shaft at an end portion on the one end side of the valve shaft. A method for manufacturing a valve device comprising the steps of:

4. 3. The method for manufacturing a valve device according to claim 1 or 2, the valve element closest to the actuator among the plurality of valve elements on the valve stem is disposed in the flow path on the side closest to the actuator across the corresponding valve seat or in the flow path on the opposite side thereof, the valve element farthest from the actuator among the plurality of valve elements on the valve stem is disposed in the flow path on a side closer to the actuator or on an opposite side of the flow path with the corresponding valve seat as a boundary, A flow path spring is provided on the valve stem between the nearest valve element and the inner wall of the flow path on the side nearest to the actuator adjacent to the corresponding valve seat, the flow path spring biasing the nearest valve element in a direction to seat it on the corresponding valve seat or biasing the farthest valve element in a direction to seat it on the corresponding valve seat. A method for manufacturing a valve device comprising the steps of:

5. 3. The method for manufacturing a valve device according to claim 1 or 2, The actuator is further provided with an actuator spring for biasing the valve bodies together with the valve shaft in a direction approaching the actuator. A method for manufacturing a valve device comprising the steps of:

6. 4. The method for manufacturing a valve device according to claim 3, The actuator is further provided with an actuator spring for biasing the valve bodies together with the valve shaft in a direction approaching the actuator. A method for manufacturing a valve device comprising the steps of:

7. 5. The method for manufacturing a valve device according to claim 4, The actuator is further provided with an actuator spring for biasing the valve bodies together with the valve shaft in a direction approaching the actuator. A method for manufacturing a valve device comprising the steps of:

8. 3. The method for manufacturing a valve device according to claim 1 or 2, the valve device is configured in the housing as a three-way valve including one inlet and two outlets communicating with the flow path; the plurality of valve seats include a first valve seat closest to the actuator and a second valve seat next to the first valve seat closest to the actuator; the flow path includes a first flow path portion that is closest to the actuator across the first valve seat, a second flow path portion that is between the first valve seat and the second valve seat, and a third flow path portion that is farthest from the actuator across the second valve seat, one of the two outlets communicates with the first flow path portion and the other communicates with the third flow path portion, and the inlet communicates with the second flow path portion; the plurality of valve bodies include a first valve body corresponding to the first valve seat and a second valve body corresponding to the second valve seat, the first valve body and the second valve body being provided on the valve stem in the second flow path portion; the first valve body has a conical shape and a tapered sealing surface on an outer periphery thereof, the sealing surface being capable of being seated on the first valve seat; The second valve body is flat and has a flat sealing surface on its periphery, and the sealing surface is provided so as to be able to seat on the second valve seat. A method for manufacturing a valve device comprising the steps of:

9. a housing having a fluid flow path; a valve seat provided in the flow path; a valve body that is capable of being seated on the valve seat; a valve stem provided with the valve body; the valve shaft includes one end and another end, the valve body is fixed to the one end, and a first screw is provided to the other end; an actuator for reciprocating the valve stem in its axial direction; the actuator includes a rotor having a second screw threadedly engaged with the first screw; the flow path is divided into a side closer to the actuator and a side farther from the actuator with the valve seat as a boundary, and the valve element is disposed on the side closer to the actuator or the side farther from the actuator so as to be able to seat on the valve seat. A method for manufacturing a valve device comprising: The housing is divided into a first housing portion and a second housing portion near the valve seat, a step of fixing the valve element to the one end side of the valve stem protruding into the flow path of the first housing portion; after the valve body is fixed, joining the first housing part and the second housing part so that the valve body is aligned with the valve seat; A method for manufacturing a valve device, comprising:

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