CN111173981B

CN111173981B - Flow control valve

Info

Publication number: CN111173981B
Application number: CN201910068178.2A
Authority: CN
Inventors: 菅沼威; 谷田贝洋臣; 吉田龙也
Original assignee: Fujikoki Corp
Current assignee: Fujikoki Corp
Priority date: 2018-01-25
Filing date: 2019-01-24
Publication date: 2023-06-20
Anticipated expiration: 2039-01-24
Also published as: CN111173981A; JP6657363B2; JP2019128036A

Abstract

Provided is a flow control valve which can prevent contact with an internal member and deformation of the internal member, and can improve torque loss by an appropriate gap to stabilize operation by suppressing tilting of a housing after welding the housing with respect to a valve body or the like. The housing (45) is welded to the outer tube member (5) of the valve body (10) with a predetermined amount of unwelded thickness left.

Description

Flow control valve

Technical Field

The present invention relates to a flow rate control valve incorporated in a refrigeration cycle or the like and used for controlling the flow rate of a fluid such as a refrigerant.

Background

For example, in a motor-driven type motor valve used as a flow rate control valve, an external screw portion of a rotor shaft (valve shaft) of a motor is screw-engaged with an internal screw hole of a female screw member fixed to a valve housing (valve body), the rotor shaft is displaced in an axial direction by the screw engagement, and a drive valve element is opened and closed by the displacement of the rotor shaft in the axial direction.

In general, in such a flow control valve, a valve body that defines a valve chamber, a housing that is a pressure vessel that houses a rotor of a motor in a rotatable bottomed cylindrical shape (cup shape), is manufactured by press forming a SUS plate, and an annular opening end portion of the housing is in contact with a flat surface of the valve body.

In general, in order to secure the compressive strength of the joint portion between the valve body and the housing, the butt welding is performed to the same depth as the plate thickness of the housing so that there is no boundary surface between the valve body and the housing due to the joining of the surfaces (for example, refer to patent document 1 below).

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2003-148643

Problems to be solved by the invention

However, in the conventional technique described in patent document 1 and the like, the open end portion of the case is welded over the entire outer periphery after being positioned in contact with the flat surface of the valve body and fixed by a jig or the like, but since the heat input at the time of welding the case is increased, the case plate thickness is entirely melted, and thus, for example, a difference in heat input occurs at a position where welding is overlapped (between the welding start position and the welding end position) and a position where welding output is different from that at the welding start position (or the welding end position) and the welding intermediate position, and a difference in penetration is increased, and the case may be inclined with respect to the valve body or the like. When the housing is fixed obliquely, the following operational failure may occur: the resin-made inner member is deformed by heat (frictional heat) in contact with the rotor as the inner member. Therefore, in order not to bring the housing into contact with the rotor, the clearance is set to be large, resulting in a large degree of torque loss.

Disclosure of Invention

The present invention has been made in view of the above-described problems, and an object thereof is to provide a flow control valve capable of suppressing tilting of a case with respect to a valve body or the like after welding, preventing contact between the case and an internal member, preventing deformation of the internal member, and improving torque loss with an appropriate gap to stabilize operation.

Means for solving the problems

In order to achieve the above object, the flow control valve according to the present invention basically has a feature that an end portion of a cylindrical housing is sealed and joined to a valve body having a valve chamber by butt welding, and the housing is welded to the valve body with a predetermined amount of unwelded thickness left.

In a preferred embodiment, the unwelded thickness is in the range of 10% to 80% of the plate thickness of the case.

In another preferred embodiment, the thickness of the case is set smaller than the thickness of the valve body at the butt-welded portion.

In another preferred embodiment, the valve body has a tubular member having a constant cross section and opening at both ends, and an end of the tubular member is joined to an end of the housing by butt welding.

In another preferred embodiment, the present invention provides: a valve shaft provided with a valve element; and a guide rod inserted in the guide rod so as to be relatively movable in the axial direction and relatively rotatable, the guide rod being fixed to the valve body, the guide rod being fixed to an upper end surface portion of the valve body via a flange-like disk, and the housing being welded to the valve body in contact with an outer peripheral portion of the flange-like disk fixed to the valve body.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, the housing is welded to the valve body with a predetermined amount of unwelded thickness left, that is, the heat input during welding is reduced, and the housing is welded to the valve body with a portion of the shape before welding left after the welding of the housing, so that the housing is less likely to tilt relative to the valve body or the like after the welding of the housing, contact with the internal components and deformation of the internal components can be prevented, torque loss can be improved by an appropriate gap, and operation can be stabilized.

Drawings

Fig. 1 is a longitudinal sectional view showing a fully closed state of an embodiment of a flow control valve (electric valve) according to the present invention.

Fig. 2 is a longitudinal sectional view showing a fully opened state of one embodiment of the flow control valve (electric valve) of the present invention.

Fig. 3 is an enlarged longitudinal sectional view of a main portion of fig. 1.

Fig. 4 is an enlarged longitudinal sectional view of a main portion of the intermediate state (lift amount: la) of fig. 1 and 2.

Fig. 5 is an enlarged longitudinal sectional view of a main portion of the intermediate state (lift amount: lb) of fig. 1 and 2.

Fig. 6 is an enlarged longitudinal sectional view of a main portion of fig. 2.

Fig. 7 is an enlarged longitudinal cross-sectional view of a main portion of the flow rate control valve (electric valve) shown in fig. 1 to 6, fig. 7 (a) is a view before welding, and fig. 7 (B) is a view after welding.

Description of symbols

1. Flow control valve (electric valve)

3. Pressure equalizing passage

4. Communication space

5. Outer cylinder part (Cylinder part)

6. First doorway (inflow entrance)

7. Second inlet and outlet (outflow)

8. Guide member

9. Base member

9e through hole

10. Valve body

11a valve seat

11b valve port

12. Valve chamber

15. Guide rod

15a large diameter cylindrical body part

15b small diameter upper part

15i female screw portion

18. Flange-like circular plate

18a outer periphery of the flange-like disk

18b notched portion of flange-like disk

20. Back pressure chamber

21. Valve shaft

21a shaft-like portion

21b upper small diameter portion

21c lower large diameter connecting part

21e external thread portion

23. Valve retainer

23a cylindrical portion

23b inner flange-like catch

23d inner peripheral step portion (stopper)

24. Valve core force application spring

25. Valve core

25a valve core part

25b main body portion

25c large diameter head

25d outer flange-like locking part

25e convex surface

26. Spring support member

26a flange-like portion

27. Gasket ring

28. Sliding surface gap

30. Rotor

35. Movable stopper for valve closing direction

36. Movable stopper for valve opening direction

45. Shell body

50. Stator

55. Fixed stopper for valve closing direction

56. Fixed stopper for valve opening direction

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Fig. 1 and 2 are longitudinal sectional views showing an embodiment of an electric valve as a flow rate control valve according to the present invention, wherein fig. 1 shows a fully closed state and fig. 2 shows a fully opened state.

In the present specification, in order to avoid complicating the description, the description of the position and direction such as up and down, left and right, front and rear, etc. is indicated by the drawings for convenience, and is not limited to the position and direction in the actual use state.

In each of the drawings, in order to facilitate understanding of the invention or to facilitate drawing, gaps formed between the members, the distance between the members, and the like may be drawn to be larger or smaller than the dimensions of the respective structural members.

The flow control valve 1 of the illustrated embodiment is an electrically operated valve for adjusting a flow rate of a refrigerant in a refrigeration cycle or the like, and includes: a valve body 10 having a bottomed cylindrical shape with an upper surface opened; a case 45, wherein a lower end portion of the case 45 is sealed and joined to an outer peripheral side of an upper end surface portion of (the outer tube member 5 of) the valve main body 10 by welding (TIG welding, plasma welding, laser welding, or the like); a guide rod 15 having a flange-like circular plate 18, the flange-like circular plate 18 being fixed to an upper end surface portion of (the outer tube member 5 of) the valve main body 10 by welding or the like; a valve shaft 21, wherein an external screw thread portion 21e is formed on the outer periphery of a shaft-shaped portion 21a of the valve shaft 21, and the external screw thread portion 21e is screwed with an internal screw thread portion 15i formed on the small-diameter upper portion 15b of the guide rod 15; a rotor 30, the rotor 30 being integrally rotatably coupled to the valve shaft 21; and a stator 50, wherein the stator 50 is externally embedded on the outer circumference of the housing 45 for driving the rotor 30 to rotate.

Here, the rotor 30 and the stator 50 constitute a stepping motor, and the female screw portion 15i of the guide rod 15 and the male screw portion 21e of the valve shaft 21 constitute a screw feed mechanism (in other words, the valve shaft 21 is inserted into the guide rod 15 in a state of being relatively movable in the axis O direction and relatively rotatable), and the stepping motor and the screw feed mechanism constitute a lift drive device for lifting and lowering the valve shaft 21 while rotating.

In this example, the valve body 10 includes a bottomed cylindrical base member 9 and an outer tube member 5 made of, for example, metal, which is disposed outside the base member 9. A thick cylindrical guide member 8 is fitted and fixed (in the example shown, caulking and fixed by caulking portions 9 a) to an upper opening of the base member 9, a valve body guide hole 8a through which a body portion 25b of a valve body 25 described later is inserted is formed in the center of the guide member 8, and a valve chamber 12 formed of a cylindrical cavity is defined inside the base member 9. A valve port 11b with a valve seat 11a is formed (longitudinally) in the bottom 9b of the base member 9.

The shape of the valve port 11b is not limited to the example shown in the drawings, but in this example, the valve port 11b is formed as a multi-stage valve port having a plurality of valve port portions each including a cylindrical portion (also referred to as a straight portion) formed of a cylindrical surface along the axis O direction (lifting direction) and a truncated cone portion connected to the cylindrical portions, and the diameter of the multi-stage valve port (the diameter of the cylindrical portion of the valve port portion) is sequentially increased in multiple stages (three stages in the illustrated example) as it is separated from the valve chamber 12.

A first port 6 formed of a pipe joint is joined to one side of the valve chamber 12 of the base member 9 by brazing or the like, and a second port 7 formed of a pipe joint is joined to (the lower side of the valve port 11b of) the bottom 9b of the base member 9 by brazing or the like.

On the other hand, the outer tube member 5 is formed of a tubular member having a constant cross section (constant inner diameter and outer diameter) and opening at both upper and lower ends, and the outer tube member 5 is formed to have a diameter slightly larger than the diameter of the cylindrical portion 9c of the base member 9. The bottom 9b of the base member 9 is formed to have a slightly larger diameter at the lower half thereof, and the lower end of the outer tube member 5 is joined to the flange-like portion 9d provided on the outer periphery of the large diameter portion by butt welding or the like, so that the outer tube member 5 is fixedly disposed on the outer periphery of the base member 9 (i.e., the outer periphery of the valve chamber 12) with a slight gap (cylindrical gap). A lower portion of the guide rod 15 is inserted into an upper portion of the outer tube member 5.

In this example, a through hole 9e is provided, and the through hole 9e is formed by a transverse hole penetrating the upper half of the bottom 9b of the base member 9 linearly in the transverse direction (the direction perpendicular to the axis O direction). The inner end side of the through hole 9e opens in a cylindrical portion constituting the valve port 11b (in particular, a cylindrical portion closest to the valve seat 11a (i.e., a cylindrical portion immediately below the valve seat 11 a) among the cylindrical portions), and the outer end side of the through hole 9e opens in the communication space 4 formed by the gap formed between the base member 9 and the outer tube member 5.

The valve shaft 21 has an upper small diameter portion 21b on which the coupling body 32 of the rotor 30 is externally fitted, a shaft-like portion 21a having a male screw portion 21e screwed into the female screw portion 15i of the guide rod 15, and a thick disk-like lower large diameter coupling portion 21c having a flange-like portion 21d positioned below the shaft-like portion 21a (the male screw portion 21 e). A cylindrical valve holder 23 is held at the lower end of the valve shaft 21, a top hole portion of the valve holder 23 is connected and fixed (in the example shown, caulking and fixing by a caulking portion 23 c) to a flange-like portion 21d provided at the upper part of the outer periphery of the lower large-diameter connecting portion 21c, and the valve holder 23 is slidably fitted into the large-diameter cylindrical body portion 15a of the guide rod 15. That is, in this example, the top hole of the cylindrical valve holder 23 is closed by the lower large-diameter connecting portion 21c of the valve shaft 21, and the valve holder 23 is rotatable and liftable integrally with the valve shaft 21. The upper portion of the valve body 25 is slidably inserted (inserted) in the vertical direction (the lifting direction) and held in the lower portion of the cylindrical portion 23a of the valve holder 23.

In this example, the valve body 25 is made of a stepped shaft-like member made of a metal such as SUS and disposed in the up-down direction (axis O direction), and the valve body 25 includes a valve core portion 25a, a cylindrical main body portion 25b connected to the upper portion of the valve core portion 25a, and a large diameter head portion 25c connected to the upper portion of the main body portion 25b, and the lower portion of the valve core portion 25a is inserted into and seated in a valve seat 11a (valve port 11 b) having an inverted truncated cone surface portion.

The main body 25b is slidably inserted into a valve body guide hole 8a of a guide member 8 fixed to the base member 9. In this example, an O-ring 8b as a sealing member is attached between a main body 25b of the valve body 25 and a valve body guide hole 8a of the guide member 8 (specifically, an annular groove provided in the valve body guide hole 8 a), and an annular seal (also referred to as a cap seal) 8c is attached to the inside of the O-ring 8b, and the seal 8c is configured by teflon (registered trademark) or the like for reducing the sliding resistance of the valve body 25 with respect to (the valve body guide hole 8a of) the guide member 8.

The O-ring 8b and the seal 8c may be attached to an annular groove provided on the outer periphery of the main body 25b of the valve body 25. In this case, an annular seal 8c is attached to the outside of the O-ring 8b as a seal member.

The tip shape of the valve body 25 (i.e., the shape of the valve body portion 25 a) is not limited to the example shown in the drawings, but since the valve body 25 is made of a solid member, it is possible to make a curved surface portion having a seating surface portion that seats on the valve seat 11a and a curved surface portion that is connected to the lower side of the seating surface portion, and the curved surface portion is designed so that an equal percentage characteristic or a characteristic similar to the flow rate characteristic can be obtained. The curved surface portion that changes the flow rate of the fluid flowing through the valve port 11b according to the lift amount may be an ellipsoidal surface portion, a plurality of conical cone surface portions whose curvature and control angle continuously or stepwise increase as approaching the tip, or the like.

An inner flange-like engaging portion 23b is provided so as to protrude inward from a lower end portion of (the cylindrical portion 23a of) the valve holder 23, a gasket 27 made of a thin annular disk (for example, made of metal such as SUS or made of resin) is interposed between (the large diameter head portion 25c of) the valve body 25 and the inner flange-like engaging portion 23b to lock the valve body 25, and the inner flange-like engaging portion 23b defines (with a small gap therebetween) a through hole through which (an upper portion 25f of the reduced diameter formed at an upper portion of) the main body 25b of the valve body 2 is inserted. When the valve holder 23 is moved upward relative to the valve body 10, the gasket 27 disposed in the inner flange-like engaging portion 23b of the valve holder 23 is hooked by the outer flange-like engaging portion 25d to be locked against removal, and the outer flange-like engaging portion 25d is formed by an outer peripheral portion (lower surface of) of the large-diameter head portion 25c of the valve body 25 (in other words, a downward annular stepped surface between the main body portion 25b and the large-diameter head portion 25 c). In addition, the gasket 27 interposed between (the inner flange-like engaging portion 23b of) the valve holder 23 and (the outer flange-like engaging portion 25d of) the valve body 25 is provided in order to reduce the rotational sliding resistance between the valve holder 23 and the valve body 25 (in other words, prevent the rotational movement of the valve holder 23 due to the lift drive from being transmitted to the valve body 25).

On the other hand, a spring support member 26 having a hat-shaped cross-section is mounted on the upper surface of the valve body 25, a valve body biasing spring 24 composed of a cylindrical compression coil spring for valve body pressing and damping is mounted between a flange-shaped portion 26a of the spring support member 26 and a lower large-diameter coupling portion 21c of the valve shaft 21 in a compressed manner, and the valve body 25 is biased downward (in the valve closing direction) by the valve body biasing spring 24 (with the spring support member 26 interposed therebetween).

In this example, in order to reduce the contact area (rotational sliding resistance) between (the upper surface of) the valve body 25 and (the lower surface of) the spring support member 26, a convex surface 25e having a flat upper surface is provided at the center of the upper surface of (the large diameter head portion 25c of) the valve body 25.

An inner peripheral stepped portion 23d serving as a stopper of a size to be engaged with the flange-like portion 26a of the spring support member 26 is formed on the lower inner periphery of the valve holder 23. When the valve holder 23 is moved upward relative to the valve body 10 to open the valve, the flange-like portion 26a of the spring support member 26, which is biased downward by (the biasing force of) the valve body biasing spring 24, is caught by and fixed to the inner peripheral stepped portion (the upward annular stepped surface) 23d of the valve holder 23. Thus, the movement of the spring support member 26 toward the valve element 25 side by (the biasing force of) the valve element biasing spring 24 in the valve holder 23 is restricted (prevented), and the biasing force of the valve element biasing spring 24 is not transmitted to the valve element 25 when the valve is opened.

Specifically, in the valve-closed state (state in which the valve holder 23 and the valve body 25 are positioned at the lowermost position, and the valve body portion 25a of the valve body 25 is pressed against the valve seat 11a by (the urging force of) the valve body urging spring 24) as shown in fig. 1 and 3, the flange-like portion 26a of the spring support member 26 and the inner peripheral stepped portion 23d (upward stepped surface) of the valve holder 23 are separated by a predetermined distance La (in the up-down direction), and the large-diameter head portion 25c of the valve body 25 and the washer 27 (upper surface) of the inner flange-like engaging portion 23b of the valve holder 23 are separated by a predetermined distance Lb (in the up-down direction) (see fig. 3). As a result, as the valve holder 23 moves upward by the lift drive device, the flange-like portion 26a of the spring support member 26 engages with the inner peripheral stepped portion 23d (upward stepped surface) of the valve holder 23, and thereafter, the spring support member 26 moves upward together (integrally) with the valve holder 23, and a gap (described later) is formed between the large-diameter head portion 25c of the valve body 25 and the spring support member 26.

The inner and outer sides of the valve holder 23 (i.e., the communication space 4 between the base member 9 and the outer tube member 5) are always in communication with the sliding surface gap 28 or the like of the cylindrical portion 23a of the valve holder 23 via the large-diameter cylindrical body portion 15a of the guide rod 15, and the valve port 11b and the back pressure chamber 20 formed on the upper side (back surface) of the valve element 25 are always in communication with each other via the pressure equalizing passage 3, and the pressure equalizing passage 3 is constituted by the communication hole 9e formed in the base member 9, the communication space 4, the sliding surface gap 28 or the like.

In this example, the entire outer periphery of the base member 9 (valve chamber 12) is set as the communication space (cylindrical gap) 4 constituting the pressure equalizing passage 3, but a D-cut surface may be formed at a predetermined position of the outer periphery of the base member 9, for example; the outer periphery (outer wall) of the base member 9 and the inner periphery (inner wall) of the outer tube member 5 are formed into a polygon or the like, and a part of the outer periphery of the base member 9 (valve chamber 12) is formed as the communication space 4.

The valve shaft 21, the valve holder 23, the valve body biasing spring 24, and the spring support member 26 are lifted and lowered substantially integrally while rotating in a state in which the valve body 25 is separated from the valve seat 11a (valve-opening state), but the valve body 25, which is inserted and held in the valve holder 23 so as to be relatively rotatable in the up-down direction (lifting direction), is lifted and lowered substantially without rotating (described later).

In this example, in the guide rod 15 having the valve body 25 (at the lower end portion) and the valve shaft 21 inserted therein, an annular flange-like disk 18 (the inner peripheral portion) is formed on the lower outer portion Zhou Chajian of the large-diameter cylindrical body portion 15a. The flange-like circular plate 18 has a cutout 18b (see fig. 3, etc.) formed by cutting out a part of the outer peripheral portion 18a (a portion protruding outward from the guide rod 15), and the guide rod 15 is fixed to a predetermined position of the valve body 10 by placing the lower surface of the cutout 18b on the upper end surface portion of (the outer tube member 5 of) the valve body 10 and welding the cutout 18b to the inner peripheral side of the upper end surface portion of (the outer tube member 5 of) the valve body 10.

In order to set the origin positions of the rotor 30 and the valve shaft 21, a valve-closing direction fixing stopper 55 having a rectangular cross section of a predetermined width, height, and depth is provided so as to protrude upward from the upper surface of the small diameter upper portion 15b of the guide rod 15, and a valve-opening direction fixing stopper 56 having a rectangular cross section of a predetermined width, height, and depth is provided so as to protrude downward from the upper portion of the large diameter cylindrical main body portion 15a of the guide rod 15.

The movable stopper 35 for closing the valve direction is screwed to the upper end portion of the male screw portion 21e of the valve shaft 21, and is locked to the disk-shaped top portion of the rotor 30. The movable stopper 35 for closing the valve is constituted by a nut portion 35a having a hexagonal planar outer shape and one side thereof being circular arc-shaped, which is screwed into the male screw portion 21e, and a stopper portion 35s having a rectangular cross section with a predetermined width, height, and depth, which is provided so as to protrude downward from the nut portion 35 a.

The valve-opening-direction movable stopper 36, which is engaged with the valve-opening-direction fixed stopper 56 in contact therewith, is screwed into the lower end portion of the male screw portion 21e of the valve shaft 21, and is locked to the lower large-diameter coupling portion 21c of the valve shaft 21. The movable stopper 36 for the valve opening direction is composed of a nut portion 36a screwed to the male screw portion 21e and a stopper portion 36s having a rectangular cross section with a predetermined width, height, and depth, which is provided so as to protrude upward from the nut portion 36 a.

The rotor 30 is composed of a cylindrical magnet 31 with a top and a connecting body 32 integrally connected to the top, and the connecting body 32 is fitted to the upper small diameter portion 21b of the valve shaft 21, and is mounted on the movable stopper 35 for closing the valve direction and welded and fixed to the upper small diameter portion 21b.

Here, a concave portion 33 is provided on the lower surface side of the top portion of the rotor 30, and the concave portion 33 includes a D-cut portion having both end portions formed in a D-shape in a plan view, is fitted in a state where one circular arc-shaped side of the nut portion 35a of the movable stopper 35 for the valve closing direction abuts against a circular arc-shaped portion other than the D-cut portion formed in the concave portion 33, and is fitted in a state where the other two sides of the nut portion 35a abut against the D-cut portion, whereby the rotor 30, the movable stopper 35 for the valve closing direction, and the valve shaft 21 are integrally rotated and lifted.

On the other hand, the lower end portion of the bottomed cylindrical case 45 is in contact with and positioned on the outer periphery 18a of the flange-like disk 18 welded and fixed to (the outer tube member 5 of) the valve body 10, and is sealed and joined to the outer periphery of the upper end portion (the upper end surface) of (the outer tube member 5 of) the valve body 10 by welding, and the stator 50 composed of the yoke 51, the bobbin 52, the coil 53, the resin mold 54, and the like is fitted to the outer periphery of the case 45. The stator 50 is fixed in position relative to the valve body 10 by a fixing member 59 provided at the bottom thereof.

Thus, when the rotor 30 is rotated, the valve shaft 21 is rotated integrally therewith, and at this time, the valve holder 23 is lifted and lowered together with the valve shaft 21 along with the valve body 25 by the screw feeding mechanism, thereby adjusting the flow rate of the refrigerant.

The operation (in particular, the valve opening operation) of the electric valve 1 having the above-described structure will be described in more detail with reference to fig. 1 and 2 and fig. 3 to 6. The valve closing operation of the electric valve 1 is an operation opposite to the following operation.

In the electrically operated valve 1 of the present embodiment, the fluid (refrigerant) flows in both directions (i.e., in both directions from the first inlet and outlet 6 to the second inlet and outlet 7 (i.e., in the transverse direction) and from the second inlet and outlet 7 to the first inlet and outlet 6 (i.e., in the transverse direction)), but the operation itself of the electrically operated valve 1 is substantially the same in the flow direction of the fluid (refrigerant), and therefore, the following description will be made on the case of the transverse-downward flow. Therefore, in the following operation, the first inlet and outlet 6 is an inlet (high pressure side), and the second inlet and outlet 7 is an outlet (low pressure side).

In the fully closed state as shown in fig. 1 and 3, the movable stopper 35 abuts against and is locked to the fixed stopper 55, and the rotor 30, the valve shaft 21, and the valve holder 23 are positioned at the lowermost position. At this time, (the lower surface of) the flange-like portion 26a of the spring support member 26 is separated from (the upper surface of) the inner peripheral stepped portion 23d (the upward stepped surface) of the valve holder 23 by a predetermined distance La, (the upper and lower directions) and (the outer peripheral lower surface of) the large-diameter head portion 25c of the valve body 25 is separated from (the upper surface of) the gasket 27 disposed in (the upper and lower directions) the inner flange-like catching portion 23b of the valve holder 23 by a predetermined distance Lb (> La), and (the valve body portion 25a of) the valve body 25 is seated (pressed) on the valve seat 11a by (the urging force of) the valve body urging spring 24 to close the valve port 11b.

When a pulse is supplied to the stator 50 from the fully closed state shown in fig. 1 and 3 as a driving mode for the valve opening direction, the rotor 30 and the valve shaft 21 are rotated, and the rotor 30, the valve shaft 21, the valve holder 23, and the movable stopper 36 for the valve opening direction are raised while being rotated by a screw feed mechanism composed of the female screw portion 15i and the male screw portion 21 e. Until the lift amount reaches La (the state shown in fig. 4), the flange-like portion 26a of the spring support member 26 is not caught by the inner peripheral stepped portion 23d of the valve holder 23, and the valve port 11b is kept closed by (the biasing force of) the valve body biasing spring 24 (the valve-closed state similar to that of fig. 1 and 3). At this time, the compression amount of the valve body urging spring 24 gradually decreases, and the entire length thereof gradually becomes longer (i.e., the pressing force against the valve body 25 becomes weaker).

When the rotor 30, the valve shaft 21, the valve holder 23, and the movable stopper 36 for the valve opening direction further rise while rotating, the flange-like portion 26a of the spring support member 26 engages with the inner circumferential stepped portion 23d of the valve holder 23 (by the urging force of the valve body urging spring 24) as shown in fig. 4 when the lift amount reaches La. Until the lift amount exceeds La and reaches Lb (the state shown in fig. 5), the valve body 25 is pressed against the valve seat 11a by a pressure difference between the upper and lower sides of the valve body 25 (i.e., the state in which the valve body 25 closes the valve port 11 b). On the other hand, the spring support member 26 disposed between the valve body biasing spring 24 and the valve body 25 moves (lifts) together with the valve holder 23 by the engagement of the flange-like portion 26a and the inner peripheral stepped portion 23d, and separates from the valve body 25, so that the biasing force of the valve body biasing spring 24 is not transmitted to the valve body 25. When the lift amount exceeds La, the flange portion 26a engages with the inner peripheral stepped portion 23d, so that the overall length of the valve body urging spring 24 is not changed.

After the flange-like portion 26a is engaged with the inner peripheral stepped portion 23d as described above, the rotor 30, the valve shaft 21, the valve holder 23, and the movable stopper 36 for the valve opening direction are further rotated and raised, and when the lift amount reaches Lb (> La), the large-diameter head portion 25c of the valve body 25 is engaged with the gasket 27 disposed in the inner flange-like engaging portion 23b of the valve holder 23 as shown in fig. 5. When the lift amount exceeds Lb, as shown in fig. 2 and 6, the valve body 25 moves (lifts) together with the valve holder 23 by engagement of the large-diameter head portion 25c with the gasket 27 disposed on the inner flange-like engagement portion 23b, and (the valve core portion 25a of) the valve body 25 is separated from the valve seat 11a, thereby opening the valve port 11b. The fluid flowing into the valve chamber 12 from the first inlet (inlet) 6 flows into the valve port 11b, and the flow rate of the fluid flowing into the valve port 11b (i.e., the fluid flowing out to the second inlet (outlet) 7) gradually increases with the rising (lift amount) of the valve holder 23 and the valve body 25. In this state, the upper and lower sides of the valve body 25, that is, the valve port 11b and the back pressure chamber 20 on the upper side of the valve body 25 are always in communication with each other via the pressure equalizing passage 3 (the through hole 9e, the communication space 4, the sliding surface gap 28, etc.), and therefore the downward pressure (the force acting in the valve closing direction) and the upward thrust (the force acting in the valve opening direction) acting on the valve body 25 are balanced (the differential pressure is offset).

As described above, the lift amount (valve opening=flow rate) of the valve body 25 is determined based on the number of pulses supplied to the stator 50, and when the pulse supply is continued, the movable stopper 36 finally comes into contact with and is locked to the valve opening direction fixed stopper 56, whereby the rotation and the lifting of the rotor 30, the valve shaft 21, and the valve holder 23 are forcibly stopped.

As described above, in the electric valve (flow rate control valve) 1 of the present embodiment, the lower end portion (lower end surface) of the housing 45 is sealed and joined (welded over the entire circumference) to the upper end portion (upper end surface) of the outer tube member 5 of the valve body 10 by butt welding. Specifically, the lower end portion (lower end surface) of the case 45 (cylindrical portion) having a relatively small plate thickness is brought into contact with the upper end portion (upper end surface) of the outer tube member 5 of the valve body 10 having a relatively large plate thickness, and is positioned and fixed by a jig or the like, and then the lower end portion (contact portion) of the case 45 is welded from the outside thereof over the entire periphery thereof, but in order to prevent the case 45 from being inclined (with respect to the axis O) with respect to the valve body 10 or the like due to welding, the following configuration is adopted.

That is, when the case 45 is butt-welded to the outer tube member 5 of the valve body 10, as shown in fig. 7 in an enlarged manner, a part of the inner peripheral side of the lower end surface of the case 45 (referred to as an unwelded thickness) is left, in other words, a part of the inner peripheral side of the lower end surface of the case 45 is pressed against the upper end surface of the outer tube member 5 of the valve body 10 without melting, and welded from the outside thereof.

That is, when the case plate thickness is tc, the designed case welding minimum thickness is tm, and the case welding thickness is ty, the case 45 is welded to the outer tube member 5 of the valve body 10 so that tc > ty > tm.

In this case, it is preferable that the case 45 is welded to the outer tube member 5 of the valve body 10 so that tc-ty (unwelded thickness) =tc×0.1 to 0.8 (i.e., unwelded thickness is in the range of 10% to 80% of the plate thickness of the case 45) under the condition of ty > tm. Further, it is preferable that the case 45 is welded to the outer tube member 5 of the valve main body 10 so that tc-ty (unwelded thickness)/(tc×0.5) (that is, unwelded thickness is half the plate thickness of the case 45).

The case plate thickness tc is set based on the following expression (1) and based on the refrigeration safety rule relation example standard (japanese: cold security example standard).

[ math 1 ]

P: design pressure (MPa)

Di: inner diameter of shell (mm)

Sigma: allowable tensile stress (N/mm) of the material ² )

η: efficiency of welded joint (e.g., 0.6)

Alpha: corrosion (mm) (in case of steel, 0.2)

As described above, in the electric valve (flow control valve) 1 of the present embodiment, the housing 45 is welded to the outer tube member 5 of the valve body 10 with a predetermined amount of unwelded thickness left, that is, the heat input at the time of welding is reduced, and the housing 45 is welded to the outer tube member 5 of the valve body 10 with a part of the shape before welding left after the housing is welded, so that the reference axis (the vertical axis defined by the lower end surface of the housing 45 and the upper end surface of the outer tube member 5 of the valve body 10) is left after the housing is welded, whereby the housing is made difficult to tilt with respect to the valve body or the like, contact with the internal member and deformation of the internal member can be prevented, torque loss can be improved by the appropriate gap 57, and the operation can be stabilized. Specifically, in the conventional electrically operated valve, the clearance between the housing and the rotor is 0.6 to 1.0 times the housing plate thickness tc, but by applying the present invention described above, the clearance 57 can be reduced to about 0.4 to 0.7 times the housing plate thickness tc. Since the torque of the motor is proportional to the square of the air gap (gap 57+ case thickness tc), the effect of improving the torque loss by applying the present invention is great.

In the present embodiment, the flange-like circular plate 18 provided on the guide rod 15 has a notch 18b (see fig. 3, etc.) formed by cutting a part of the outer peripheral portion 18a of the flange-like circular plate 18, and the guide rod 15 is fixed to a predetermined position of the valve body 10 by welding the notch 18b to the inner peripheral side of the upper end surface portion of the valve body 10. On the other hand, the case 45 is welded and fixed to the valve body 10 in a state where it is positioned (with its lower end portion inner periphery) in contact with the outer peripheral portion 18a of the flange-like circular plate 18 welded and fixed to the valve body 10. Therefore, by welding the case 45 so as not to weld the inner peripheral surface of the case 45 but to leave it, the positional displacement of the flange-like disk 18 and the decrease in the welding strength of the notched portion 18b can be reliably prevented.

Further, since the flange-like disk 18 is insert-molded to the guide rod 15, deterioration due to heat of the resin portion of the guide rod 15 can be prevented by welding the housing 45 so as to leave the inner peripheral surface of the housing 45 without welding it. For example, since the guide rod 15 of the above embodiment is made of PPS resin except for the flange-like circular plate 18, the following concern can be eliminated: the strength is reduced by heat input during welding of the flange-like circular plate 18, and the guide rod 15 is displaced from a predetermined position. Of course, if the case 45 is welded so as to remain without welding the inner peripheral surface of the case 45 of the present embodiment, there is no concern that foreign matter generated by thermal decomposition of PPS resin may be mixed into the refrigerant.

In order to prevent oxidation, the butt welding is usually performed under a protective gas (rare gas) atmosphere, but in the case where the thickness of the case is completely melted as in the conventional technique, oxidation is likely to occur on the inner side where the protective gas is difficult to supply.

In addition, naturally, the present invention can also be applied to other types of electric type flow control valves that use a stepping motor or the like having a stator and a rotor to raise and lower (move) a valve shaft and arbitrarily finely adjust a lift amount (valve opening), and electromagnetic type flow control (switching) valves that use, for example, an electromagnetic type to raise and lower a valve body, other than the electric valve of the above-described embodiment.

Claims

1. A flow control valve in which an end portion of a cylindrical housing is sealed and joined to a valve body having a valve chamber by butt welding, comprising:

a valve shaft provided with a valve element; and

a guide rod, in which the valve shaft is inserted in a state of being relatively movable in the axial direction and relatively rotatable, and which is fixed to the valve main body,

the guide rod is fixed to the upper end surface of the valve main body via a flange-like circular plate,

the flange-like disk has a notch portion formed by cutting a part of the outer peripheral portion of the flange-like disk, and the guide rod is fixed to a predetermined position of the valve body by welding the notch portion to the inner peripheral side of the upper end surface portion of the valve body,

the housing is in contact with an outer peripheral portion of the flange-like disk fixed to the valve body, and is welded to the valve body with a predetermined amount of unwelded thickness left.

2. The flow control valve of claim 1, wherein,

the unwelded thickness is in the range of 10% to 80% of the plate thickness of the case.

3. A flow control valve according to claim 1 or 2, wherein,

at the butt welded portion, the thickness of the case is set smaller than the thickness of the valve main body.

4. A flow control valve according to claim 1 or 2, wherein,

the valve body has a tubular member with a constant cross section and opening at both ends, and an end of the tubular member is joined to an end of the housing by butt welding.

5. The flow control valve according to claim 3, comprising: