JP2007024274A - Valve device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain a decrease in the number of parts, simplification of structure, miniaturization and improvement in sealing performance of a valve device with a stepping motor as a drive source. <P>SOLUTION: The valve device comprises the stepping motor including a rotor 20 having an internal screw 24, and a stator 30; a shaft 40 having an external screw 42 screwed with the internal screw 24 of the rotor 20 and supported to freely reciprocate in an axial direction X; a valve element 50 provided on the tip side of the shaft 40; a housing 10; and the like. The valve element 50 includes a valve holder 51 molded using a resin material integrally with the shaft 40, and a valve part 52 connected to the valve holder 51 and seatable on a valve seat 12 of a passage. Since the valve holder 51 of the valve element 50 is insert-molded integrally with the shaft 40, and the valve part 52 is connected to the molded valve holder 51, the decrease in the number of parts, simplification of structure, a decrease in assembling man-hours and miniaturization can be attained while ensuring cut-off performance by the valve part 52. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a valve device that opens and closes a valve body that opens and closes a passage with a stepping motor, and particularly relates to a valve device that is disposed in a fluid passage in a hot water heating system or other fluid supply system.

  Conventional valve devices include a cylindrically formed stator, a stepping motor comprising a cylindrical rotor that is rotatably supported inside the stator and can rotate stepwise, and is formed on the inner peripheral surface of the rotor. A shaft having a male screw that engages with a female screw and a shaft portion having an oval cross section, a valve body that is provided at the tip of the shaft to open and close the passage, and restricts the moving end position of the shaft in the axial direction A pin provided on the outer peripheral surface of the shaft, a slide bearing that supports the shaft portion of the shaft so that it cannot rotate and is slidable in the axial direction, and the rotor is appropriately driven to rotate the shaft. A valve body that reciprocates in the axial direction through an opening and closing passage is known (for example, see Patent Document 1).

However, in this valve device, as a method for regulating the rotation of the shaft, a shaft portion having an oval cross section is formed on the shaft, and a bearing that slidably supports the shaft portion is employed. The shape of the shaft is complicated and not easy to manufacture, and an O-ring is provided to prevent fluid leakage from this interface while ensuring slidability between the shaft (shaft) and the bearing. Is difficult.
Further, as a method for defining the moving end position of the valve body and the shaft in the axial direction, since separate pins are implanted in the shaft, the number of parts is large, and the number of assembling steps is increased accordingly.

  Other valve devices include a cylindrically formed stator, a rotor that is rotatably supported inside the stator and can be driven to rotate stepwise, a shaft that is fixed to the rotor and has a male screw at the tip, etc. A stepping motor comprising: a valve body (holder) that has a female screw threadedly engaged with a male screw of the shaft and is supported so as to be movable in the axial direction; and that controls the rotation of the valve body and its outer peripheral surface; A cylindrical guide that contacts and slidably supports the valve body in the axial direction, a coil spring that is arranged in a compressed state between the valve body and the guide and biases the valve body in the valve closing direction, etc. There is known one in which a valve body reciprocates in an axial direction to open and close a passage when a rotor is driven to rotate appropriately (see, for example, Patent Document 2).

However, in this valve device, since the female screw of the valve body is screwed into the male screw formed at the tip of the shaft, a certain length is required from the rotor to the tip of the shaft, and the device is small in the axial direction. Is difficult. Further, as a method for regulating the moving end position of the valve body in the axial direction, the end of the valve body that does not rotate is brought into direct contact with the end of the rotating rotor. May cause generation of wear powder, or may cause wear powder to bite into the sliding interface, and the functional reliability is not sufficient.
In addition, since the outer diameter of the valve body is larger than that of the shaft, an O-ring or the like that prevents fluid leakage from this interface while ensuring slidability between the outer peripheral surface of the valve body and the guide. It is difficult to arrange the seal member.
Furthermore, since it is necessary to assemble the valve body by screwing it into the shaft while compressing the coil spring, the assembling work is not easy.

Japanese Patent Laid-Open No. 3-27579 Japanese Patent No. 3444243

  The present invention has been made in view of the circumstances of the above prior art, and its object is to reduce the number of parts, simplify the structure, reduce the number of assembly steps, reduce the size, etc. It is an object of the present invention to provide a valve device that can easily assemble a sealing member such as the above and can improve the sealing performance at the sliding interface.

The valve device of the present invention has a stepping motor including a rotor having a female screw and a stator arranged around the rotor, a male screw screwed into the female screw of the rotor, and is capable of reciprocating and rotating in the axial direction. A valve device comprising: a shaft that is impossiblely supported; a valve body that is provided on a tip end side of the shaft and opens and closes a passage; and a housing that houses at least a stepping motor. The valve holder is integrally formed using the valve holder, and the valve portion is coupled to the valve holder and can be seated on the valve seat of the passage.
According to this configuration, when the rotor rotates, the shaft moves in the axial direction, and the valve body opens and closes the passage or sets the opening to a predetermined degree of opening to control the fluid flow rate. Here, the valve holder of the valve body is molded integrally with the shaft (for example, insert molding), and the valve portion is coupled to the molded valve holder, so water stop performance by the valve portion is ensured However, it is possible to reduce the number of parts, simplify the structure, reduce the number of assembly steps, and reduce the size.

In the above configuration, the shaft has a fitting protrusion that protrudes from the end face of the valve holder and whose tip has an enlarged diameter, and the valve portion is coupled to the valve holder and fitted to the fitting protrusion. Can be adopted.
According to this configuration, since the valve portion is not only coupled to the valve holder but also fitted to the fitting protrusion of the shaft protruding from the end face of the valve holder, the valve portion is firmly fixed, and the valve The durability of the part can be increased.

The above configuration includes a shaft holder having a through hole that is fitted and fixed to the inside of the housing and slidably supports the shaft, and the shaft holder is movable in the axial direction while restricting rotation. It is possible to adopt a configuration having a stopper portion that regulates the moving end position of the valve body in the axial direction when the guide portion that guides the valve and the end portion of the valve holder abut on each other.
According to this configuration, the shaft holder guide portion restricts the rotation of the valve holder to restrict the rotation of the shaft, and the shaft holder stopper portion restricts the movement of the valve holder in the axial direction of the valve body. A moving end position is defined.
As described above, in the engagement relationship between the valve holder and the shaft holder, the rotation preventing function of the shaft and the valve body and the stopper function of the shaft and the valve body are obtained. In comparison, the structure can be simplified and the manufacturing cost can be reduced. Further, since both the valve holder and the shaft holder do not rotate (relative rotation does not occur), wear due to sliding does not occur, and functional reliability is improved.

In the above configuration, the guide portion of the shaft holder has the restriction pieces radially arranged around the axis, and the valve holder is regulated to be arranged radially around the axis so as to be engaged and guided by the restriction pieces. A configuration with pieces can be employed.
According to this configuration, since the rotation of the valve body and the shaft is regulated by the engagement of the regulating piece of the guide portion and the regulated piece of the valve holder that are radially arranged around the axis, the regulating force is around the axis. It is possible to prevent the regulation force from being locally increased.

The said structure WHEREIN: The structure which has a bearing holding part holding the bearing which supports a rotor rotatably can be employ | adopted for a shaft holder.
According to this configuration, since the rotor and the shaft are supported by the shaft holder, which is the same member, it is possible to prevent axial misalignment and the like, and to obtain a smooth rotational motion of the rotor and a smooth linear motion of the shaft. it can.

In the above configuration, the shaft holder includes a male holder and a female holder having a center on the axis to be fitted and coupled with each other in the axial direction, and the male holder defines a through-hole and a housing. An enlarged cylindrical portion fitted into the inner diameter of the cylindrical holder, and a reduced diameter cylindrical portion having an inner diameter larger than that of the through hole. The female holder has an annular groove for defining the through hole and fitting the reduced diameter cylindrical portion, Use a configuration in which an O-ring is mounted inside the reduced-diameter cylindrical portion to seal the shaft in a slidable contact with the male holder and female holder fitted together. Can do.
According to this configuration, when assembling the apparatus, the shaft integrally provided with the valve body is passed through the female holder, and then the O-ring is further passed through the male holder, or the O-ring is provided in the reduced diameter cylindrical portion. The O-ring is slidably fitted onto the shaft by fitting the male holder with the female holder and then coupling the male holder to the female holder. Can be done. Thus, since the female holder, O-ring, and male holder can be assembled from the same direction with respect to the shaft, the assembly setup can be simplified, and the lubricant can be easily used even after the O-ring is assembled. Can be applied. Further, the sealing performance around the shaft can be improved reliably.

The said structure WHEREIN: The structure by which the O-ring which contacts the inner wall of a housing is mounted | worn on the outer side of a reduced diameter cylindrical part is employable.
According to this structure, the sealing performance between a housing and a shaft holder can also be ensured, and the sealing performance as the whole apparatus can be improved.

The said structure can employ | adopt a structure including the motor housing which accommodates a stepping motor, and the valve housing which accommodates a valve body and defines a valve seat.
According to this configuration, since the valve body is also accommodated in the valve housing, there is no possibility that the valve body collides with other objects when the valve device is handled, and the quality during the handling can be ensured.

  According to the valve device configured as described above, it is possible to easily assemble a seal member such as an O-ring while achieving reduction in the number of parts, simplification of the structure, reduction in the number of assembly steps, miniaturization, and the like. A valve device with improved sealing performance at the dynamic interface can be obtained.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings.
1 to 3 show an embodiment of a valve device according to the present invention, FIG. 1 and FIG. 2 are sectional views of the valve device, and FIG. 3 is an exploded perspective view showing a part of the valve device.

As shown in FIGS. 1 to 3, the valve device includes a housing 10, a rotor 20 accommodated in the housing 10 and rotatably supported, and two stators 30 stacked in the axial direction X around the rotor 20. A shaft 40 coupled to the rotor 20 and supported linearly and movably; a valve body 50 provided on the tip side of the shaft 40; a shaft holder 60 that slidably supports the shaft 40; O-rings 70 and 80 that are mounted, a bearing 90 and a support plate 100 that rotatably support the rotor 20, a thrust bearing 110 that urges the rotor 20 toward one side in the axial direction X, and the like.
That is, in this valve device, a stepping motor that can be rotated stepwise is formed by the rotor 20, the stator 30, and the like, and the valve body 50 is driven to open and close by this stepping motor.

  As shown in FIGS. 1 and 2, the housing 10 is formed of a resin material, and is formed of a motor housing 11 that houses the rotor 20 and the stator 30, a valve housing 12 that forms a fluid passage and a valve seat, and the like. Yes.

The motor housing 11 holds the support plate 100 and the thrust bearing 110, holds the stator 30 inside, and rotatably accommodates the rotor 20 inside the stator 30, and electrically connects the connector 11 a and the valve housing 12. And a cylindrical fitting portion 11b and the like to be connected.
The valve housing 12 includes an inflow passage 12a through which fluid flows in, an outflow passage 12b through which fluid flows out, a valve seat 12c on which the valve body 50 can be seated and closed, and a cylinder that is fitted into the fitting portion 11b of the motor housing 11. 12d and the like.
As described above, the housing 10 is formed by the motor housing 11 that accommodates the stepping motor and the valve housing 12 that accommodates the valve body 50 and defines the valve seat 12c. Since it is accommodated in the valve housing 12, there is no possibility that the valve body collides with other objects when the valve device is handled, and it is possible to guarantee the quality during handling.

The rotor 20 is supported by the bearing 90 and the support plate 100 so as to be rotatable about the axis X while the movement in the thrust direction is restricted by the thrust bearing 110 inside the motor housing 11.
The rotor 20 includes a cylindrical portion 21 made of a resin material, a magnet 22 fixed to the outer periphery of the cylindrical portion 21, and a shaft that protrudes from both ends of the cylindrical portion 21 and is slidably fitted to the bearing 90 and the support plate 100. It is formed by the female screw 24 etc. which were formed in the inner peripheral surface of the part 23 and the cylindrical part 21. FIG. The magnets 22 are integrally molded on the outer periphery of the cylindrical portion 21, and a plurality of N poles and S poles are alternately arranged in the rotation direction and are magnetized.

  As shown in FIGS. 1 and 2, the two stators 30 are joined by sandwiching the exciting coil 31, the bobbin 32 around which the coil 31 is wound, and the bobbin 32, and the outer peripheral surface of the rotor 20 ( It is formed by a pair of yokes 33 having a plurality of claw-shaped magnetic pole pieces facing the magnet 22).

The shaft 40 is formed of a metal material so that the cross section is substantially circular, and, as shown in FIGS. 1 to 3, the coupling portion 41 of the valve body 50 on one end side (tip side), and the other end side. A male screw 42 is formed on the outer peripheral surface so as to be screwed with the female screw 24 over a predetermined area.
As shown in FIGS. 1 to 3, the coupling portion 41 is a non-rotating knurl 41 a and a valve that are formed to securely couple a valve body 50 (a valve holder 51 to be described later) that is integrally molded. It is formed by a fitting protrusion 41b or the like formed so as to protrude from the end surface of the holder 51 and to expand the diameter of the tip.

As shown in FIGS. 1 to 3, the valve body 50 can be seated on the valve seat 12c by being joined to the valve holder 51, which is insert-molded with a resin material so as to surround the knurl 41a of the shaft 40, and the valve holder 51. It is formed by the valve part 52.
Thus, since the valve holder 51 of the valve body 50 is insert-molded integrally with the shaft 40, and the valve portion 52 is coupled to the molded valve holder 51, the water stop performance by the valve portion 52. While ensuring, the number of parts can be reduced to facilitate assembly, and the structure can be simplified and miniaturized.

The valve holder 51 is formed by a plurality of regulated pieces 51b that are radially arranged around the axis X so as to be engaged in a concave portion 51a and a regulating piece 62c of the shaft holder 60 described later to be guided in the axial direction X. Yes. The valve holder 51 is molded so that the fitting protrusion 41b of the shaft 40 protrudes from the end face (the bottom face of the recess 51a). Here, since the valve holder 51 is molded so as to surround the knurled 41a having irregularities on the surface, the valve holder 51 is firmly coupled to the shaft 40 so as not to idle.
The valve portion 52 is formed of a rubber material or the like that can be elastically deformed so as to be in close contact with the valve seat 12c. The valve portion 52 is fitted into the recess 51a of the valve holder 51 and is fitted into the fitting protrusion 41b of the shaft 40 to be coupled. Has been. Thus, the valve portion 52 is not only fitted to the valve holder 51 but also fitted to the fitting protrusion 41b of the shaft 40 protruding from the end surface of the valve holder 51 (the bottom surface of the recess 51a). Therefore, it is fixed firmly and can improve durability.

As shown in FIGS. 1 to 3, the shaft holder 60 includes a male holder 61 and a female holder 62 having a center on the axis X so as to be fitted and coupled with each other in the axis direction X.
The male holder 61 includes a through-hole 61a that slidably supports the shaft 40, a diameter-enlarged cylindrical portion 61b that is fitted to the valve housing 12, a reduced-diameter cylindrical portion 61c that has a larger inner diameter than the through-hole 61a, and a bearing 90. Is formed by a cylindrical bearing holding portion 61d and the like.
The female holder 62 engages with a through hole 62 a that slidably supports the shaft 40, an annular groove 62 b into which the reduced diameter cylindrical portion 61 c of the male holder 61 is fitted, and a regulated piece 51 b of the valve holder 51. The valve body 50 (and the shaft 40) are brought into contact with the end portions of the plurality of restricting pieces 62 c and the valve holder 51 arranged radially around the axis X as guide portions for guiding in the axial direction X while restricting the rotation of the valve 40. ) Is formed by an end face 62d or the like as a stopper portion for defining the moving end position in the axial direction X.

That is, the shaft holder 60 is fitted and fixed to the inside of the housing 10 and supports the shaft 40 in a slidable manner, and the plurality of regulating pieces 62c (guide portions) regulate the rotation in the axial direction X. The valve holder 51, that is, the shaft 40 is movably guided, and the end face 62 d (stopper portion) abuts the end of the valve holder 51 to receive it, thereby defining the moving end position of the valve body 50 in the axial direction X. To do.
As described above, in the engagement relationship between the valve holder 51 and the shaft holder 60, the rotation preventing function and the stopper function of the shaft 40 and the valve body 50 are obtained, so that compared to the case where the rotation preventing function and the stopper function are provided separately. The structure can be simplified and the manufacturing cost can be reduced. Further, since both the valve holder 51 and the shaft holder 60 do not rotate (no relative rotation occurs), wear due to sliding does not occur, and functional reliability is improved.
Here, since the plurality of restricting pieces 62c and the restricting pieces 51b arranged radially around the axis line X are employed as the structure that generates the rotation preventing function, the restricting force is smoothed around the axis line X. It is possible to prevent local increase.

Further, in the shaft holder 60, an O-ring 70 is mounted on the inner side of the reduced diameter cylindrical portion 61c of the male holder 61 in a state where the male holder 61 and the female holder 62 are fitted to each other. 40 is slidably contacted and sealed. Further, an O-ring 80 is mounted on the outer side of the reduced diameter cylindrical portion 61 c of the male holder 61 so as to seal between the inner wall of the valve housing 12 and the shaft holder 60.
The O-rings 70 and 80 are made of a rubber material. Here, the O-ring 70 needs to seal the contact interface surely, particularly in a state where the shaft 40 slides in the axial direction X. It may be reduced to improve wear resistance.

As described above, since the shaft holder 60 is divided into the male holder 61 and the female holder 62, the shaft 40 integrally provided with the valve body 50 is assembled as shown in FIG. Then, the male holder 61 is passed through the O-ring 70 and then the male holder 61, or the O-ring 70 and the O-ring 80 are mounted on the inner side and the outer side of the reduced diameter cylindrical portion 61c. Then, by fitting the male holder 61 to the female holder 62 and coupling them, the O-ring 70 is also slidably fitted to the shaft 40 and the O-ring 80 is brought into close contact with the inner wall of the valve housing 12. As a result, the O-rings 70 and 80 can be easily assembled.
Thus, since the female holder 62, the O-rings 70 and 80, and the male holder 61 can be assembled from the same direction with respect to the shaft 40, the assembly setup can be simplified, and the assembly of the O-ring 70 is possible. The lubricant can be easily applied later, and the sealing performance around the shaft 40 can be improved with certainty.

  As shown in FIGS. 1 and 2, the bearing 90 supports one shaft portion 23 of the rotor 20 in a radial direction so as to be rotatable, and a bearing holding portion of a male holder 61 constituting the shaft holder 60. It is fitted and held in 61d. Thus, since the rotor 20 and the shaft 40 are supported by the shaft holder 60 (male holder 61), which is the same member, misalignment of the axial center can be prevented, smooth rotation of the rotor 20 and the shaft 40 can be prevented. Smooth linear motion can be obtained.

As shown in FIGS. 1 and 2, the support plate 100 supports the other shaft portion 23 of the rotor 20 in a radial direction so as to be rotatable, and is made of a motor material by using a metal material having excellent wear resistance. 11 and insert molding.
As shown in FIGS. 1 and 2, the thrust bearing 110 is formed by a coil spring 111 housed in the motor housing 11, and a sphere 112 that is biased in the axial direction X by the biasing force of the coil spring 111. In contrast, an urging force is exerted in one direction of the axial direction X (toward the valve body 50).

Next, the operation of the valve device will be described. When the coil 31 is energized in one direction and the rotor 20 rotates in one direction, the threaded relationship between the female screw 24 of the rotor 20 and the male screw 42 of the shaft 40 is established. As shown in FIG. 1, the valve body 50 (and the shaft 40) moves linearly in one direction of the axial direction X (downward in the drawing). And the valve part 52 contacts and seats on the valve seat 12c of the valve housing 12, and at the same time, the passages 12a and 12b are closed and stopped.
In this state, the valve portion 52 completely shuts off the passages 12a and 12b, so that a water stopping action for completely stopping the flow of fluid such as tap water or hot water can be obtained.

On the other hand, when the coil 31 is energized in the other direction and the rotor 20 rotates in the other direction, as shown in FIG. 2, the shaft is connected via the screwed relationship between the female screw 24 of the rotor 20 and the male screw 42 of the shaft 40. The valve body 50 (and the shaft 40) linearly moves in the other direction of the axial direction X (upward in the drawing) so that a part of 40 further enters the inside of the rotor 20.
When the end of the valve holder 51 (the end of the regulated piece 51b) comes into contact with the end surface 62d of the shaft holder 60, the valve 52 moves in the reciprocating direction X farthest from the valve seat 12c of the valve housing 12. At the same time as being positioned at the end position, the passages 12a and 12b are fully opened and stopped.

  Further, since the valve element 50 can be adjusted to an intermediate opening degree between fully open and fully closed by appropriately adjusting the energization to the coil 31 and appropriately controlling the rotation amount of the stepping motor (rotor 20), the flow rate of fluid Can be controlled. Furthermore, since the valve body 50 (shaft 40) is linearly moved by the rotation of the stepping motor, the movement pitch of the valve body 50 (shaft 40), that is, the opening degree of the valve body 50 can be adjusted with high accuracy. The flow rate can be controlled with high accuracy.

  Therefore, when this valve device is used as a control valve for a hot water heating system or the like, the flow rate of the hot water can be controlled with high accuracy, and the heating temperature can be controlled to a desired set temperature with high accuracy and high responsiveness. In addition, it is possible to prevent the impact sound or the like caused by the collision of the valve body 50 with the valve seat 12c or the water hammer and the like, and the occurrence of the impact sound or the like that is annoying.

In the above embodiment, a plurality of regulating pieces 62 d provided on the female holder 62 and a plurality of regulated pieces 51 b provided on the valve holder 51 are employed as guide portions that regulate the rotation of the valve body 50 (and the shaft 40). However, the present invention is not limited to this, and other configurations can be adopted as long as the rotation is restricted. The male holder 61 and the female holder 62 may be configured so that the male mold and the female mold are reversed.
In the above-described embodiment, the configuration in which the valve housing 12 that defines the valve seat 12c and the passages 12a and 12b is employed as the housing 10 in addition to the motor housing 11 is shown. And you may provide the seat surface of the valve body 50 in the side by which this valve apparatus is attached.
In the above embodiment, the configuration in which the fitting protrusion 41b is provided in the coupling portion 41 of the shaft 40 is shown. However, the fitting protrusion 41b is not provided, and is flush with the recess 51a (the bottom surface) of the valve holder 51. Alternatively, it may be formed so as to be embedded in the valve holder 51. Moreover, you may form so that the valve part 52 may be fitted to the valve holder 51, without providing the recessed part 51a in the valve holder 51, and connecting the valve part 52 to the end surface.

  As described above, the valve device of the present invention can easily assemble a seal member such as an O-ring while achieving reduction in the number of parts, simplification of the structure, reduction in assembly man-hours, miniaturization, and the like. In addition, since the sealing performance at the sliding interface can be improved, it can be applied to a hot water heating system or the like that controls the flow rate of the fluid by opening and closing the passage. It is also useful as a valve device for controlling

1 shows an embodiment of a valve device according to the present invention and is a cross-sectional view showing a state in which a valve body is closed. 1 shows an embodiment of a valve device according to the present invention, and is a cross-sectional view showing a state in which a valve body is opened. It is a disassembled perspective view which shows a part of valve apparatus which concerns on this invention.

Explanation of symbols

X axial direction 10 housing 11 motor housing 12 valve housing 12a inflow passage 12b outflow passage 12c valve seat 20 rotor 21 cylindrical portion 22 magnet 23 shaft portion 24 female screw 30 stator 31 exciting coil 22 bobbin 33 yoke 40 shaft 41 coupling portion 41a Knurl 41b Fitting protrusion 42 Male thread 50 Valve body 51 Valve holder 51a Recess 51b Regulated piece 52 Valve portion 60 Shaft holder 61 Male holder 61a Through hole 61b Expanded cylindrical portion 61c Reduced diameter cylindrical portion 61d Bearing holding portion 62 Female die Holder 62a Through hole 62b Annular groove 62c Restriction piece (slide part)
62d End face (stopper part)
70, 80 O-ring 90 Bearing 100 Support frame 110 Thrust bearing

Claims (8)

A stepping motor including a rotor having a female screw and a stator arranged around the rotor, and a male screw that is screwed into the female screw of the rotor, is supported so as to be reciprocable in the axial direction and non-rotatable. A valve device provided with a shaft, a valve body that is provided on a distal end side of the shaft and opens and closes a passage, and a housing that houses at least the stepping motor;
The valve body includes a valve holder that is integrally molded with a resin material with respect to the shaft, and a valve portion that is coupled to the valve holder and can be seated on the valve seat of the passage.
A valve device characterized by that. The shaft has a fitting protrusion that protrudes from the end face of the valve holder and whose tip is enlarged in diameter,
The valve portion is coupled to the valve holder and is fitted to the fitting protrusion.
The valve device according to claim 1. A shaft holder having a through-hole that is fitted and fixed inside the housing and slidably supports the shaft;
The shaft holder is a guide portion that guides the valve holder so as to be movable in the axial direction while restricting rotation, and a stopper that defines the movement end position of the valve body in the axial direction by abutting the end portions of the valve holder. Having a part,
The valve device according to claim 1 or 2, wherein The guide portion of the shaft holder has restriction pieces arranged radially around the axis,
The valve holder has regulated pieces radially arranged around an axis to be engaged and guided by the regulated piece,
The valve device according to claim 3. The shaft holder includes a bearing holding portion that holds a bearing that rotatably supports the rotor.
The valve device according to any one of claims 2 to 4, wherein The shaft holder includes a male holder and a female holder having a center on an axis to be fitted and coupled with each other in the axial direction;
The male holder includes a reduced diameter cylindrical portion that defines the through hole and is fitted to the housing, and a reduced diameter cylindrical portion having an inner diameter larger than the through hole.
The female holder has an annular groove for defining the through hole and fitting the reduced diameter cylindrical portion,
On the inner side of the reduced-diameter cylindrical portion, an O-ring is mounted to seal the shaft in a slidable contact with the male holder and the female holder fitted to each other.
The valve device according to any one of claims 2 to 5, wherein On the outside of the reduced diameter cylindrical portion, an O-ring that comes into contact with the inner wall of the housing is mounted.
The valve device according to claim 6. The housing includes a motor housing that houses the stepping motor, and a valve housing that houses the valve body and defines the valve seat.
The valve device according to any one of claims 1 to 7, wherein

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