CN107542966B

CN107542966B - Electric valve

Info

Publication number: CN107542966B
Application number: CN201710320809.6A
Authority: CN
Inventors: 吉田龙也; 矢泽将志
Original assignee: Fujikoki Corp
Current assignee: Fujikoki Corp
Priority date: 2016-06-29
Filing date: 2017-05-09
Publication date: 2020-03-27
Anticipated expiration: 2037-05-09
Also published as: JP6721237B2; JP2018003899A; CN107542966A

Abstract

An electrically operated valve provided with a compression coil spring (61) which biases a movable screw portion (33) in an ascending/descending direction with respect to a fixed screw portion (23) so that an upper surface of the movable screw portion in a screw feed mechanism (28) abuts against a lower surface of the fixed screw portion or so that a lower surface of the movable screw portion in the screw feed mechanism (28) abuts against an upper surface of the fixed screw portion, at least when a valve body (14) is at a lowermost position, irrespective of a flow direction of a fluid, and specifically, the compression coil spring (61) biases a valve shaft holder (30) coupled and fixed to a valve shaft (10) in the ascending/descending direction with respect to a guide bush (20) attached and fixed to a valve body (40). This allows the electrically operated valve to suppress a change in flow rate associated with a change in the flow direction of the fluid (refrigerant) when the valve body is at the lowermost position.

Description

Electric valve

Technical Field

The present invention relates to an electrically operated valve used as a flow rate control valve or the like in a refrigeration cycle mounted on an air conditioner, a refrigerator, or the like, and more particularly to a non-valve-closing type electrically operated valve in which a gap of a predetermined size is formed between a valve element and a valve seat portion even when the valve element is at a lowermost position (normally, in a fully closed state).

Background

As such a motor-operated valve, for example, a motor-operated valve is known which has a structure including: a valve shaft; a guide rod having a cylindrical portion into which the valve shaft is inserted; a cylindrical valve holder which is held and fixed to a lower end portion of the valve shaft and is inserted into the guide rod; a valve body inserted into the valve holder in a state of being relatively movable and rotatable in an axial direction with respect to the valve shaft, biased downward by compressing a coil spring installed between the valve body and the valve shaft, and locked by the valve holder in a retaining manner; a valve main body having a valve seat portion that is in contact with and separated from the valve body, and to which the guide rod is attached and fixed; a housing coupled to the valve body; a rotor disposed on an inner periphery of the housing; a rotor holder that couples the rotor and the valve shaft via a coupling member that is fitted and fixed to an upper end portion of the valve shaft; a recess formed in the rotor holder for fitting with an engagement portion provided in the rotor; a stator disposed on an outer periphery of the housing to drive the rotor to rotate; an internal thread member disposed on an inner peripheral side of the cylindrical portion of the guide bar; a screw feed mechanism which is composed of a fixed screw portion formed on an inner periphery of the female screw member and a movable screw portion formed on an outer periphery of the valve shaft, and which is used for bringing the valve body and the valve seat portion into contact with and away from each other; and a stopper mechanism disposed on an outer periphery of the cylindrical portion of the guide rod and restricting rotation and up-and-down movement of the rotor, the stopper mechanism being composed of a spiral fixed stopper having an upper locking portion and a lower locking portion, and a ring-shaped or spiral slider provided with a first abutting portion abutting and locked with the upper locking portion and a second abutting portion abutting and locked with the lower locking portion, the slider being assembled to a spiral portion of the fixed stopper, the first abutting portion being pushed by a pushing portion provided to the rotor when the rotor rotates, the slider moving up and down while rotating until the first abutting portion abuts with the upper locking portion or the second abutting portion abuts with the lower locking portion, at an origin position where the second abutting portion of the slider abuts with the lower locking portion and is stopped, a gap of a predetermined size is formed between the valve body and the valve seat portion (see, for example, patent document 1).

In the electrically operated valve having the above-described configuration, even when the valve body is located at the lowermost position (normally, in the fully closed state), a gap of a predetermined size is formed between the valve body and the valve seat portion, and therefore, compared with a normal valve-closing electrically operated valve, the electrically operated valve can reliably prevent the valve body from biting into the valve seat portion, and has an advantage of preventing poor operation due to seizure of the compressor when the electrically operated valve is used in an air conditioner.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 5164579

However, in the conventional non-valve-closing type motor-operated valve as described above, the first conduit for one side portion of the valve chamber of the refrigerant inlet/outlet valve main body and the second conduit for the lower portion of the refrigerant inlet/outlet valve chamber are connected and fixed by brazing or the like, and the fluid (refrigerant) flows in both directions of one direction (normal direction) from the first conduit to the second conduit via the valve chamber and the other direction (reverse direction) from the second conduit to the first conduit via the valve chamber, but a backlash (thread backlash) is inevitably present in the screw feed mechanism (between the fixed thread portion and the movable thread portion constituting the screw feed mechanism), and therefore, when the flow direction of the fluid (refrigerant) changes from the normal direction to the reverse direction or from the reverse direction to the normal direction, the spool is urged by the pressure of the fluid, and the spool moves up and down with respect to the valve seat portion by the backlash (thread backlash) (see fig. 9 a), Fig. 9 (B)).

In the conventional motor-operated valve, the valve body that controls the flow rate of the fluid flowing through the valve port orifice is generally formed of an inverted conical surface or an inverted conical surface (tapered surface). Therefore, the following problems occur: when the valve body is located at the home position (also referred to as the lowest position, or a position where the number of pulses supplied to the motor is 0 pulse) due to the vertical movement of the valve body with respect to the valve seat portion caused by the change in the flow direction of the fluid as described above, the flow rate of the fluid flowing through the valve port orifice (also referred to as 0 pulse flow rate) changes before and after the change in the flow direction of the fluid (see fig. 10).

Disclosure of Invention

The present invention has been made in view of the above problems, and an object of the present invention is to provide an electrically operated valve capable of suppressing a flow rate change caused by a change in the flow direction of a fluid (refrigerant) when a valve body is located at a lowermost position.

In order to solve the above problem, an electrically operated valve according to the present invention includes: a valve shaft provided with a valve core; a valve body provided with a valve port orifice having a valve seat portion that is separated from or close to the valve body, and formed with a valve chamber into which fluid is introduced and discharged; a motor having a rotor coupled to the valve shaft and a stator for rotating the rotor; a screw feed mechanism that is configured by a fixed screw portion provided on the valve body side and a movable screw portion provided on the valve shaft side, and that raises and lowers the valve body of the valve shaft relative to the valve seat portion of the valve body in accordance with rotational driving of the rotor; and a lower stopper mechanism for restricting a rotational drop of the valve shaft, a gap is formed between the valve body and the valve seat portion when the valve body is located at the lowermost position by the lower stopper mechanism, fluid flows in both a forward direction from the valve chamber to the valve port orifice and a reverse direction from the valve port orifice to the valve chamber, the motor-operated valve is provided with a backlash preventing biasing member, and when the valve body is at least at the lowermost position, regardless of the direction of the fluid flow, the backlash preventing biasing member biases the movable screw portion of the screw feeding mechanism in a lifting direction with respect to the fixed screw portion, so that the upper surface of the movable screw part abuts against the lower surface of the fixed screw part or the lower surface of the movable screw part abuts against the upper surface of the fixed screw part.

In a more specific aspect, the electrically operated valve includes: a valve shaft provided with a valve core; a valve shaft holder coupled and fixed to the valve shaft; a guide bush in which the valve shaft is inserted in a state of being relatively movable and rotatable in an axial direction; a valve body provided with a valve port orifice having a valve seat portion that is separated from or close to the valve body, and a valve chamber in which a fluid is introduced and discharged, and the guide bush is fixed to the valve body; a motor having a rotor coupled to the valve shaft holder and a stator for rotating the rotor so as to rotate the valve shaft holder with respect to the guide bush; a screw feed mechanism that is configured by a fixed screw portion formed in the guide bush and a movable screw portion formed in the valve shaft holder, and that raises and lowers the valve body of the valve shaft relative to the valve seat portion of the valve body in accordance with rotational driving of the rotor; and a lower stopper mechanism including a fixed stopper body provided to a lower stopper and a movable stopper body provided to the valve shaft holder, for restricting a rotational downward movement of the valve shaft holder, wherein the lower stopper has a female screw portion screwed to the fixed screw portion of the guide bush, and when the valve body is located at a lowermost position by the lower stopper mechanism, a gap is formed between the valve body and the valve seat portion, and a fluid flows in both a forward direction from the valve chamber to the valve port orifice and a reverse direction from the valve port orifice to the valve chamber, and the electric valve is provided with a backlash prevention biasing member for biasing the valve shaft holder in an upward and downward direction with respect to the guide bush regardless of a flow direction of the fluid at least when the valve body is located at the lowermost position, so that the upper surface of the movable screw portion in the screw feeding mechanism abuts against the lower surface of the fixed screw portion or the lower surface of the movable screw portion in the screw feeding mechanism abuts against the upper surface of the fixed screw portion.

Preferably, the backlash preventing biasing member is interposed between the valve body and the valve shaft.

Preferably, the backlash preventing biasing member is interposed between the guide bush and the valve shaft.

Preferably, the backlash preventing biasing member is interposed between the lower stopper and the valve shaft holder.

Preferably, a housing is coupled and fixed to the valve body, the rotor is rotatably inserted into the housing, the stator is externally fitted to the housing, and the backlash preventing biasing member is inserted between the housing and the valve shaft holder.

In a preferred aspect, the backlash preventing biasing member is set so that the biasing force thereof acts at least in a low flow rate region in which the valve opening degree of the valve body with respect to the valve seat portion is equal to or smaller than a predetermined valve opening degree.

Drawings

Fig. 1 is a vertical cross-sectional view showing a first embodiment of an electrically operated valve according to the present invention.

Fig. 2 is an enlarged vertical cross-sectional view of an important part of the motor-operated valve shown in fig. 1.

Fig. 3 is a diagram showing flow rate characteristics of the motor-operated valve shown in fig. 1.

Fig. 4 is a vertical cross-sectional view showing a second embodiment of the motor-operated valve according to the present invention.

Fig. 5 is a vertical cross-sectional view showing a third embodiment of the motor-operated valve according to the present invention.

Fig. 6 is a vertical cross-sectional view showing a fourth embodiment of the motor-operated valve according to the present invention.

Fig. 7 is a vertical cross-sectional view illustrating a fifth embodiment of the electrically operated valve according to the present invention.

Fig. 8 is a vertical cross-sectional view showing a modification of the motor-operated valve shown in fig. 7.

Fig. 9 is an enlarged vertical cross-sectional view of an important part of a conventional motor-operated valve, in which fig. 9(a) is a diagram showing a forward flow state and fig. 9(B) is a diagram showing a reverse flow state.

Fig. 10 is a diagram showing flow rate characteristics of a conventional motor-operated valve.

Description of the symbols

1 electric valve (first embodiment)

2 electric valve (second embodiment)

3 electric valve (third embodiment)

4 electric valve (fourth embodiment)

Electric valve 5 (fifth embodiment)

5A electric valve (modification of fifth embodiment)

10 valve shaft

14 valve core

20 guide bush

23 fixed thread part (external thread part)

24 fixed stop body

25 lower stop

25a mounting groove (fourth embodiment)

27 fitting part

27b Flange part (third embodiment)

28 screw thread feeding mechanism

29 lower stop mechanism

30 valve shaft holder

33 Movable screw part (internal screw part)

34 Movable stop body

40 valve body

40a valve chamber

41 first opening

41a first conduit

42 second opening

42a second conduit

45 bottom wall

45f annular flat surface

46 valve port orifice

46a valve seat portion

46s straight part

47 Flange shaped part

50 stepping motor

51 rotor

52 stator

55 casing

60 compression coil spring (force application component for force application in valve closing direction)

61 compression coil spring (force application component for preventing backlash)

70 locking part for preventing falling

71 push nut

72 rotor pressing member

75 restoring spring (restoring component)

O axis

Detailed Description

Hereinafter, an embodiment of an electrically operated valve according to the present invention will be described with reference to the drawings. In addition, for easy understanding of the invention or for convenience in drawing, there are cases where: in the drawings, gaps formed between components, pitches between components, and the like are exaggeratedly drawn. In the present specification, the description of the positions and directions indicating up, down, left, right, and the like is based on the directional arrows in fig. 1 and the like, and does not refer to the positions and directions in an actual use state.

In the present specification, a direction from the first pipe connected to a side of the valve chamber in the valve body to the second pipe through the valve chamber and the valve port orifice formed in a bottom of the valve chamber in the longitudinal direction is defined as a "forward direction", and a direction from the second pipe connected to a lower side of the valve chamber to the first pipe through the valve port orifice formed in a bottom of the valve chamber is defined as a "reverse direction".

[ first embodiment ]

< Structure and operation of Motor-operated valve >

The motor-operated valve 1 of the illustrated embodiment mainly includes: a valve shaft 10; a guide bush 20; a valve shaft holder 30; a valve main body 40; a housing 55; a stepping motor 50 composed of a rotor 51 and a stator 52; a compression coil spring (valve closing direction urging member) 60; an anti-drop locking member 70; a screw feed mechanism 28 and a lower stop mechanism 29.

The valve shaft 10 has an upper small diameter portion 11, an intermediate large diameter portion 12, and a lower small diameter portion 13 from the upper side, and a stepped reverse-truncated-cone-shaped valve element 14 is integrally formed at the lower end of the lower small diameter portion 13, and the valve element 14 controls the flow rate of a fluid (refrigerant) flowing through the valve port orifice 46.

As is clear from fig. 1 and 2, the valve body 14 includes, from the upper side (the valve chamber 40a side), an upper tapered surface portion 14t and a lower tapered surface portion 14u, the upper tapered surface portion 14t being formed of an inverted conical land surface that is long in the direction of the center circumferential line O (the vertical direction), and the lower tapered surface portion 14u being formed of an inverted conical land surface that is larger in control angle (intersection angle with a line parallel to the center axis O of the valve body 14) than the upper tapered surface portion 14 t.

The guide bush 20 is formed of a cylindrical body, the valve shaft 10 (the intermediate large diameter portion 12 thereof) is inserted into the cylindrical body in a state of being relatively movable (slidable) in the axis O direction and relatively rotatable about the axis O, and the upper portion of the guide bush 20 extends to the side of the upper small diameter portion 11 of the valve shaft 10. A fixed screw portion (male screw portion) 23 is formed on the outer periphery of (the upper and lower center portions of) the guide bush 20, and this fixed screw portion 23 constitutes one side of a screw feed mechanism 28 that raises and lowers the valve body 14 of the valve shaft 10 relative to the valve seat portion 46a of the valve main body 40 in accordance with the rotational drive of the rotor 51. The lower portion (portion below the fixed screw portion 23) of the guide bush 20 is a large-diameter fitting portion 27 that is fitted into the fitting hole 44 of the valve main body 40. A lower stopper 25 is screwed and fixed to the fixed screw portion 23 (a portion of the fixed screw portion 23 located below the valve shaft holder 30) with a slight gap from the upper surface 27a of the fitting portion 27, and a fixed stopper 24 is integrally provided on the outer periphery of the lower stopper 25 in a protruding manner, and the fixed stopper 24 constitutes one side of a lower stopper mechanism 29 that restricts the downward rotational movement of the valve shaft holder 30 (i.e., the valve shaft 10 coupled to the valve shaft holder 30). In addition, the upper surface 27a of the fitting portion 27 is a stopper portion that restricts downward movement of the lower stopper 25 (in other words, defines a downward movement limit position or a most downward movement position of the lower stopper 25).

Here, the lower stopper 25 is fixed to the fixed thread portion 23 of the guide bush 20 with a slight gap from the upper surface 27a of the fitting portion 27, but if a gap of a predetermined size is formed between the valve body 14 and the seat portion 46a when the valve body 14 is located at the lowermost position (origin position), for example, the lower stopper 25 may be fixed to the fixed thread portion 23 of the guide bush 20 so as to be in contact with the upper surface 27a of the fitting portion 27.

The valve shaft holder 30 has a cylindrical portion 31 in which the guide bush 20 is inserted, and a top portion 32 in which an insertion hole 32a through which the upper end portion of (the upper small diameter portion 11 of) the valve shaft 10 is inserted is formed to penetrate the cylindrical portion 31. A movable screw portion (female screw portion) 33 is formed on the inner periphery of (the lower half of) the cylindrical portion 31 of the valve shaft holder 30, the movable screw portion 33 is screwed with the fixed screw portion 23 of the guide bush 20 to constitute the screw feeding mechanism 28, and a movable stopper 34 is integrally provided on the outer peripheral lower end of the cylindrical portion 31 of the valve shaft holder 30 in a protruding manner, and the movable stopper 34 constitutes the other side of the lower stopper mechanism 29.

A compression coil spring (valve closing direction urging member) 60 is compression-fitted between a step surface (upward) formed between the upper small diameter portion 11 and the intermediate large diameter portion 12 of the valve shaft 10 and a lower surface of the top portion 32 of the valve shaft holder 30 so as to be inserted into the upper small diameter portion 11 of the valve shaft 10, and the compression coil spring 60 urges the valve shaft 10 and the valve shaft holder 30 in a direction in which they are separated from each other in the vertical direction (axis O direction), in other words, the compression coil spring 60 always urges the valve shaft 10 (valve body 14) downward (valve closing direction).

The valve main body 40 is formed of a cylindrical body made of metal such as brass, SUS, or the like. The valve body 40 has a valve chamber 40a into which the lead-out fluid is introduced and guided, a first pipe 41a is connected and fixed by brazing or the like to a first opening 41 provided in a lateral direction of a side portion of the valve chamber 40a, an insertion hole 43 and a fitting hole 44 are formed in a top portion of the valve chamber 40a, the valve shaft 10 (the intermediate large diameter portion 12 thereof) is inserted into the insertion hole 43 in a state of being relatively movable (slidable) in the axis O direction and relatively rotatable about the axis O, a lower portion (the fitting portion 27) of the guide bush 20 is fitted and fixed to the fitting hole 44, and a second pipe 42a is connected and fixed by brazing or the like to a second opening 42 provided in a vertical direction of the lower portion of the valve chamber 40 a. A valve port orifice 46 having a substantially truncated cone shape is formed in a bottom wall 45 provided between the valve chamber 40a and the second opening 42, the valve port orifice 46 has a valve seat portion 46a that is in contact with and separated from or close to the valve body 14, and a straight portion 46s (see fig. 2) having a cylindrical surface (having a constant inner diameter in the vertical direction) is provided in the valve seat portion 46 a.

The (inner diameter of the) straight portion 46s is designed to be slightly smaller than the diameter of the lower small diameter portion 13 of the valve shaft 10.

An annular flat surface 45f is formed around the valve port orifice 46 (valve seat portion 46a) on the upper surface of the bottom wall portion 45 of the valve body 40, and a compression coil spring (backlash prevention urging member) 61 is compression-fitted around the lower small diameter portion 13 of the valve shaft 10 in the valve chamber 40a between the annular flat surface 45f and a step surface (facing downward) formed between the lower small diameter portion 13 and the intermediate large diameter portion 12 of the valve shaft 10, and the compression coil spring 61 urges the valve shaft 10 and the valve body 40 in a direction of separating from each other in the vertical direction (axis O direction), in other words, upwardly urges the valve shaft 10. The biasing force (compression force) of the compression coil spring (backlash prevention biasing member) 61 is set to be smaller than the biasing force (compression force) of the compression coil spring (valve closing biasing member) 60 so as not to hinder the position (e.g., the origin position) of the valve body 14 with respect to the valve seat portion 46a, which is determined by the screw feeding mechanism 28.

A flange-shaped plate 47 is fixed to an upper end portion of the valve body 40 by caulking or the like, and a lower end portion of a cylindrical housing 55 with a top is joined to a step portion provided on an outer periphery of the flange-shaped plate 47 by butt welding.

A rotor 51 is rotatably disposed (inserted) inside the housing 55 and outside the guide bush 20 and the valve shaft holder 30, and a stator 52 for driving the rotor 51 to rotate is disposed (externally fitted) outside the housing 55, and the stator 52 is composed of a yoke 52a, a coil frame 52b, a stator coil 52c, a resin mold case 52d, and the like. A plurality of terminals 52e are connected to the stator coil 52c, and a plurality of wires 52g are connected to these terminals 52e via a substrate 52f, so that the stator coil 52c is energized and excited to rotate the rotor 51 disposed in the housing 55 about the axis O.

The rotor 51 disposed in the housing 55 is engaged with and supported by the valve shaft holder 30, and the valve shaft holder 30 is configured to rotate together with (integrally with) the rotor 51.

Specifically, the rotor 51 has a double-pipe structure including an inner pipe 51a, an outer pipe 51b, and a connecting portion 51c, the connecting portion 51c connecting the inner pipe 51a and the outer pipe 51b at a predetermined angular position about the axis O, and vertical grooves 51d extending in the axis O direction (vertical direction) are formed in the inner periphery of the inner pipe 51a (for example, at angular intervals of 120 ° about the axis O).

On the other hand, a projecting strip 30a extending in the vertical direction is provided (e.g., at an angular interval of 120 ° around the axis O) so as to project from (an upper half of) the outer periphery of the valve shaft holder 30, and upward facing engagement surfaces (not shown) for supporting the rotor 51 are formed on both sides of a lower portion of the projecting strip 30 a.

The vertical groove 51d of the inner cylinder 51a of the rotor 51 is engaged with the protrusion 30a of the valve shaft holder 30, and the rotor 51 is supported and fixed to the valve shaft holder 30 in a state of being positioned with respect to the valve shaft holder 30 by the lower surface of the inner cylinder 51a of the rotor 51 being in contact with the locking surface of the valve shaft holder 30, and the valve shaft holder 30 rotates together with the rotor 51 while supporting the rotor 51 in the housing 55.

A retaining engagement member 70 including a pressing nut 71 and a rotor pressing member 72 is disposed above the rotor 51 and the valve shaft holder 30 to prevent relative movement between the valve shaft holder 30 and the rotor 51 in the vertical direction (in other words, to press the rotor 51 downward with respect to the valve shaft holder 30) and to connect the valve shaft 10 and the valve shaft holder 30, the pressing nut 71 is fixed to the upper end portion of (the upper small diameter portion 11 of) the valve shaft 10 by press fitting, welding, or the like, and the rotor pressing member 72 is interposed between the pressing nut 71 and the rotor 51 and is formed of a disc-shaped member having a through hole 72a formed in the center thereof for inserting the upper end portion of the valve shaft 10. That is, the rotor 51 is sandwiched between the valve shaft holder 30 biased upward by the biasing force of the compression coil spring 60 and the rotor pressing member 72. The height (in the vertical direction) from the upper end of the valve shaft holder 30 to the engagement surface is substantially the same as the height (in the vertical direction) of the inner cylinder 51a of the rotor 51, and the upper surface of (the top portion 32 of) the valve shaft holder 30 abuts against the lower surface (flat surface) of the rotor pressing member 72.

Further, a return spring (return member) 75 formed of a coil spring that biases the valve shaft holder 30 toward the guide bush 20 is attached to the outside of the push nut 71 fixed to the upper end portion of the valve shaft 10, and the return spring 75 prevents the screw engagement between the fixed screw portion 23 of the guide bush 20 and the movable screw portion 33 of the valve shaft holder 30 from being disengaged due to the excessive upward movement of the valve shaft holder 30 relative to the guide bush 20 during operation. When the valve body 14 is located near the lowest position (origin position), in other words, in a low flow rate region where the valve opening degree is small (the valve opening degree is equal to or smaller than a predetermined valve opening degree), the return spring 75 does not urge the valve shaft holder 30 toward the guide bush 20 (that is, does not urge the valve shaft holder 30).

In the motor-driven valve 1, when the valve element 14 is located at the lowest position (the original position), a gap of a predetermined size is formed between (the upper tapered surface portion 14t of) the valve element 14 and the seat portion 46a so as to prevent, for example, the valve element 14 from biting into the seat portion 46a and ensure controllability in a low flow rate region.

In the motor-operated valve 1 having this configuration, when the rotor 51 is rotated by energization and excitation of (the stator coil 52c of) the stator 52, the valve shaft holder 30 and the valve shaft 10 integrated with the rotor 51 are rotated. At this time, the valve shaft 10 is lifted and lowered together with the valve body 14 by the screw feed mechanism 28 including the fixed screw portion 23 of the guide bush 20 and the movable screw portion 33 of the valve shaft holder 30, and thereby the clearance (lift amount, valve opening degree) between the valve body 14 and the valve seat portion 46a is increased or decreased, and the flow rate of the fluid such as the refrigerant is adjusted. Even when the movable stopper 34 of the valve shaft holder 30 abuts against the fixed stopper 24 of the lower stopper 25 fixed to the guide bush 20 and the valve body 14 is located at the lowermost position, a predetermined amount of flow rate can be secured because a gap (required lift amount when the valve is closed) is formed between the valve body 14 and the valve seat portion 46a (see fig. 3).

In the screw feed mechanism 28 for raising and lowering the valve body 14 with respect to the valve seat portion 46a, there is a backlash (thread clearance) between the movable thread portion 33 of the valve shaft holder 30 coupled to the valve body 14 (valve shaft 10) and the fixed thread portion 23 of the guide bush 20 coupled and fixed to the valve main body 40, but in the motor-operated valve 1 of the present embodiment, between the annular flat surface 45f of the valve main body 40 and the step surface formed between the lower small diameter portion 13 and the intermediate large diameter portion 12 of the valve shaft 10, i.e., around the lower small diameter portion 13 of the valve shaft 10 in the valve chamber 40a, a compression coil spring 61 is compression-fitted, therefore, the valve shaft holder 30 coupled and fixed to the valve shaft 10 is biased upward with respect to the guide bush 20 coupled and fixed to the valve body 40, and the upper surface side of the movable screw portion 33 of the valve shaft holder 30 is brought into contact with (pressed against) the lower surface side of the fixed screw portion 23 of the guide bush 20 (see fig. 2).

In the electric valve 1 of the present embodiment, fluid (refrigerant) flows in two directions, specifically, in two directions, i.e., in the lateral → downward direction (hereinafter, this state is referred to as a forward flow state) in which the valve body 14 is biased downward and in the forward flow state and in the reverse flow state in which the valve body 14 is biased upward, from the first pipe 41a (first opening 41) through the valve chamber 40a and the valve port orifice 46, and in the direction (i.e., in the downward → lateral direction) of the second pipe 42a (second opening 42) (hereinafter, this state is referred to as a reverse flow state) in which the fluid flows in two directions, i.e., in the lateral → downward direction) in which the second pipe 42a (second opening 42) through the valve port orifice 46 and the valve chamber 40a, and in which the valve body 14 is biased upward, as described above, the upper surface side of the movable screw portion 33 of the valve shaft holder 30 is brought into contact with (pressed against) the lower surface side of the fixed screw portion 23 of the guide bush 20 by (the urging force of) the compression coil spring 61. Therefore, the backlash (thread clearance) between the fixed thread portion 23 and the movable thread portion 33 constituting the screw feeding mechanism 28 disappears, and even if the flow direction of the fluid (refrigerant) changes from the forward direction to the reverse direction or from the reverse direction to the forward direction, the valve element 14 does not move up and down with respect to the valve seat portion 46, and therefore, as shown in fig. 3, it is possible to reliably suppress a change in the flow rate accompanying the change in the flow direction of the fluid (refrigerant) when the valve element 14 is at the lowermost position.

Further, by always biasing the valve shaft 10 upward with respect to the valve main body 40 by compressing the coil spring 61, the same flow rate characteristic can be achieved in both the forward flow state and the reverse flow state as shown by the solid line in fig. 3. However, the valve shaft 10 may be biased upward with respect to the valve body 40 by the compression coil spring 61 between the low flow rate region where the valve opening degree is small (the biasing force by the compression coil spring 61 acts on the valve shaft 10), and the biasing force by the compression coil spring 61 may not act on the valve shaft 10 after switching from the low flow rate region to the large flow rate region (after reaching the inflection point of the flow rate at the intermediate opening degree). That is, the natural length of the compression coil spring 61 may be designed to be shorter than the distance between the annular flat surface 45f of the valve body 40 after the inflection point of the flow rate at the intermediate opening and the stepped surface formed between the lower small diameter portion 13 and the intermediate large diameter portion 12 of the valve shaft 10. In this case, as shown by the broken line in fig. 3, in a large flow rate region after the inflection point of the flow rate exceeding the intermediate opening, the flow rate characteristics (only the degree of backlash (thread clearance)) change in the forward flow state and the reverse flow state, but in a low flow rate region where the valve opening degree before the inflection point of the flow rate exceeding the intermediate opening is small, the same flow rate characteristics are obtained in both the forward flow state and the reverse flow state, and the distance (valve opening degree) over which the biasing force generated by the compression coil spring 61 acts on the valve shaft 10 can be limited. Therefore, it is possible to reliably avoid a flow rate change accompanying a change in the flow direction of the fluid (refrigerant) in a low flow rate region where fine flow rate adjustment is required (in other words, it is possible to ensure controllability of the fluid flow rate in the low flow rate region), and it is possible to restrict an increase in the torque (rotational torque) due to the urging force of the compression coil spring 61.

< method for assembling motor-operated valve >

When an example of the assembly process of the above-described motor-operated valve 1, particularly an example of the origin position (the lowermost position) alignment process of the valve element 14, is roughly described with reference to fig. 1, first, the valve shaft 10, the guide bush 20, the lower stopper 25, the compression coil spring 60, the valve shaft holder 30, the rotor 51, the compression coil spring 61, the valve body 40, and the like are attached. At this time, the lower stopper 25 is screwed to the guide bush 20 so as to be relatively rotatable. At this stage, the lower stopper 25 may be disposed in contact with the stopper 27a of the guide bush 20, or may be disposed at a distance from the stopper 27 a. Next, (the upper tapered surface portion 14t of) the valve body 14 provided at the lower end portion of the valve shaft 10 abuts on the valve seat portion 46a, the compression coil spring 60 and the compression coil spring 61 are slightly compressed, the movable stopper body 34 of the valve shaft holder 30 abuts on the fixed stopper body 24 of the lower stopper 25, and the valve shaft holder 30, the rotor 51, and the valve shaft 10 are lowered while being rotated by the screw feed mechanism 28 configured by the fixed screw portion 23 of the guide bush 20 and the movable screw portion 33 of the valve shaft holder 30 until (the lower surface of) the lower stopper 25 abuts on the stopper portion 27a of the guide bush 20. In a state where the valve shaft holder 30 is located at the most downward movement position and the valve body 14 is further lowered than the most lowered position, the rotor pressing member 72 is fitted into the upper end portion of the valve shaft 10, and the pressing nut 71 is externally fitted and fixed by press-fitting, welding, or the like.

Next, from the above state, the screw feed mechanism 28 raises and removes the integrated assembly of the valve shaft 10, the valve shaft holder 30, the rotor 51, the retaining engagement member 70 (the pressing nut 71 and the rotor pressing member 72) and the like from the guide bush 20 while rotating, and then rotates the lower stopper 25 in the valve opening direction (counterclockwise in the plan view in the example shown in the figure) with respect to the guide bush 20 by a predetermined rotation angle. At this time, the lower stopper 25 may be rotated until it rises from the stopper 27a of the guide bush 20, or may be rotated while being held in contact with the stopper 27a of the guide bush 20 (only by the degree of backlash). Next, the lower stopper 25 is coupled and fixed to (the fixed screw portion 23 of) the guide bush 20 by welding, adhesion, or the like so as not to be relatively rotatable, and then the assembly is mounted to the guide bush 20 again by the screw feeding mechanism 28. Thus, since the position of the fixed stopper body 24 of the lower stopper 25 with respect to the guide bush 20 changes, even when the movable stopper body 34 of the valve shaft holder 30 abuts against the fixed stopper body 24 of the lower stopper 25 and the valve shaft holder 30 is located at the most downward movement position (that is, when the valve body 14 is located at the most downward position), a gap of a predetermined size (a gap of a size H in the upward and downward direction in the forward flow state) is formed between the valve body 14 and the valve seat portion 46 a. At this time, as described above, the upper surface side of the movable screw portion 33 of the valve shaft holder 30 is brought into contact with the lower surface side of the fixed screw portion 23 of the guide bush 20 by (the urging force of) the compression coil spring 61. In addition, although the step of rotating the lower stopper 25 in the valve opening direction by a predetermined rotation angle with respect to the guide bush 20 after the assembly is lifted up and removed from the guide bush 20, and connecting and fixing the lower stopper 25 to the guide bush 20 by welding, adhesion, or the like so as not to be relatively rotatable has been described, if a gap of such a degree that the assembly can be formed is not necessary to remove the assembly from the guide bush 20, the gap will be described as follows: the lower stopper 25 can be rotated in the valve opening direction by a predetermined rotation angle with respect to the guide bush 20 only by raising the assembly with respect to the guide bush 20, and the lower stopper 25 can be coupled and fixed to the guide bush 20 by welding, adhesion, or the like so as not to be relatively rotatable.

[ second embodiment ]

The configuration of the compression coil spring (the backlash preventing biasing member) 61 of the motor-operated valve 2 according to the second embodiment is different from that of the motor-operated valve 1 according to the first embodiment, but the other configurations of the motor-operated valve 2 according to the second embodiment are substantially the same as those of the motor-operated valve 1 according to the first embodiment. Therefore, the same reference numerals are given to portions corresponding to the respective portions of the motor-operated valve 1 of the first embodiment, and detailed description thereof is omitted, and only the differences will be described in detail below.

In the motor-operated valve 2 according to the second embodiment, the lower small diameter portion 13 of the valve shaft 10 is formed with a step, the upper portion of the lower small diameter portion 13 extends to the inside of the guide bush 20, an insertion hole 43 is provided in the top of the valve chamber 40a of the valve body 40, and (the upper large diameter portion of) the lower small diameter portion 13 of the valve shaft 10 is inserted into the insertion hole 43 in a state of being relatively movable (slidable) in the axis O direction and relatively rotatable about the axis O.

A compression coil spring (backlash preventing biasing member) 61 is compression-fitted between the bottom surface of the fitting hole 44 of the valve body 40 (the portion around the insertion hole 43) and a stepped surface (facing downward) formed between the lower small diameter portion 13 and the intermediate large diameter portion 12 of the valve shaft 10, that is, around the lower small diameter portion 13 of the valve shaft 10 inside the guide bush 20, and the compression coil spring 61 biases the valve shaft 10 and the valve body 40 in a direction in which they are separated from each other in the vertical direction (the direction of the axis O), in other words, the compression coil spring 61 biases the valve shaft 10 upward. Here, similarly, the biasing force (compression force) of the compression coil spring (backlash prevention biasing member) 61 is set to be smaller than the biasing force (compression force) of the compression coil spring (valve closing biasing member) 60 so as not to hinder the position (for example, the origin position) of the valve body 14 with respect to the valve seat portion 46a, which is determined by the screw feeding mechanism 28.

In the electric valve 2 of the present embodiment, similarly, in both the forward flow state and the reverse flow state, the upper surface side of the movable screw portion 33 of the valve shaft holder 30 is brought into contact with (pressed against) the lower surface side of the fixed screw portion 23 of the guide bush 20 by the (biasing force of) the compression coil spring 61, and therefore, the same operational effects as those of the electric valve 1 of the first embodiment can be obtained.

In the motor-operated valve 2 of the present embodiment, the compression coil spring 61 (instead of being disposed in the valve chamber 40a) is disposed inside the guide bush 20 in the fitting hole 44 of the valve main body 40, and therefore, the flow of the fluid (refrigerant) in the valve chamber 40a is not obstructed, and an effect such as a change in the characteristics (a change in the spring force) of the compression coil spring 61 due to the flow of the fluid (refrigerant) in the valve chamber 40a can be obtained.

[ third embodiment ]

The arrangement of the compression coil spring (backlash preventing biasing member) 61 of the motor-operated valve 3 according to the third embodiment is different from that of the motor-operated valve 2 according to the second embodiment, but the other configurations of the motor-operated valve 3 according to the third embodiment are substantially the same as those of the motor-operated valve 2 according to the second embodiment. Therefore, the same reference numerals are given to portions corresponding to the portions of the motor-operated valve 2 of the second embodiment, and detailed description thereof is omitted, and only the differences will be described in detail below.

In the motor-operated valve 3 according to the third embodiment, a flange-like portion 27b that protrudes inward is provided at the lower end portion of (the fitting portion 27 of) the guide bush 20 that is fitted into the fitting hole 44 of the valve main body 40. In this example, the hole formed by the flange-shaped portion 27b has a diameter substantially the same as the diameter of the insertion hole 43 provided in the top portion of the valve chamber 40a of the valve body 40, and the lower small-diameter portion 13 (the upper large-diameter portion thereof) of the valve shaft 10 is inserted into the flange-shaped portion 27b so as to be relatively movable (slidable) in the axis O direction and relatively rotatable about the axis O.

Further, a compression coil spring (backlash preventing urging member) 61 is compression-fitted between the upper surface of the flange-shaped portion 27b of the guide bush 20 and a step surface (downward) formed between the lower small diameter portion 13 and the intermediate large diameter portion 12 of the valve shaft 10, that is, around the lower small diameter portion 13 of the valve shaft 10 inside the guide bush 20, in the same manner as in the second embodiment, and the compression coil spring 61 urges the valve shaft 10 and the valve body 40 in a direction of separating them from each other in the vertical direction (the axis O direction), that is, the compression coil spring 61 urges the valve shaft 10 upward.

Therefore, it is apparent that the motor-operated valve 3 of the present embodiment can also obtain the same operational effects as the motor-operated valve 2 of the second embodiment described above.

[ fourth embodiment ]

The configuration of the compression coil spring (the backlash preventing biasing member) 61 of the motor-operated valve 4 according to the fourth embodiment is different from that of the motor-operated valve 1 according to the first embodiment, but the other configurations of the motor-operated valve 4 according to the fourth embodiment are substantially the same as those of the motor-operated valve 1 according to the first embodiment. Therefore, the same reference numerals are given to portions corresponding to the respective portions of the motor-operated valve 1 of the first embodiment, and detailed description thereof is omitted, and only the differences will be described in detail below.

In the motor-operated valve 4 according to the fourth embodiment, an annular mounting groove 25a is provided on (the outer periphery of) the lower stopper 25 screwed to the fixed screw portion 23 of the guide bush 20, and a compression coil spring (backlash prevention urging member) 61 is compressively fitted between the (upward) bottom surface of the mounting groove 25a and the lower surface of (the cylindrical portion 31 of) the valve shaft holder 30, and the compression coil spring 61 urges the valve shaft holder 30 and the lower stopper 25 coupled and fixed to the guide bush 20 in a direction in which they are separated from each other in the lifting direction (the direction of the axis O), in other words, the compression coil spring 61 urges the valve shaft holder 30 upward.

In this example, the intermediate large diameter portion 12 of the valve shaft 10 is provided so as to extend into the valve chamber 40a of the valve body 40 through an insertion hole 43 provided in the top of the valve chamber 40a of the valve body 40.

In the motor-operated valve 4 of the present embodiment, similarly, in both the forward flow state and the reverse flow state, the upper surface side of the movable screw portion 33 of the valve shaft holder 30 is brought into contact with (pressed against) the lower surface side of the fixed screw portion 23 of the guide bush 20 by the (biasing force of) the compression coil spring 61, and therefore, the same operational effects as those of the motor-operated valve 1 of the first embodiment can be obtained.

In the motor-operated valve 4 of the present embodiment, since (the biasing force of) the compression coil spring 61 directly acts on the valve shaft holder 30 having the movable screw portion 33, an effect is obtained in which a change in the flow rate caused by a change in the flow direction of the fluid (refrigerant) can be more reliably suppressed.

[ fifth embodiment ]

The arrangement of the compression coil spring (the backlash preventing biasing member) 61 and the return spring 75 of the motor-operated valve 5 according to the fifth embodiment is different from that of the motor-operated valve 1 according to the first embodiment, but the other configuration of the motor-operated valve 5 according to the fifth embodiment is substantially the same as that of the motor-operated valve 1 according to the first embodiment. Therefore, the same reference numerals are given to portions corresponding to the respective portions of the motor-operated valve 1 of the first embodiment, and detailed description thereof is omitted, and only the differences will be described in detail below.

In the motor-operated valve 5 according to the fifth embodiment, the upper end portion of the return spring 75 externally attached to the pressing nut 71 is provided to extend to the top of the housing 55, and the return spring 55 in a compressed state is interposed between the rotor pressing member 72 disposed on the valve shaft holder 30 and the housing 55. That is, in the present embodiment, the return spring 75 is compression-fitted (via the rotor pressing member 72) between the housing 55 and the valve shaft holder 30, and biases the valve shaft holder 30 in the vertical direction (the direction of the axis O) with respect to the housing 55 coupled and fixed to the valve body 40, in other words, the return spring 75 functions (is used) as a compression coil spring (a backlash preventing biasing member) 61 that biases the valve shaft holder 30 downward. That is, in the present embodiment, the return spring 75 (the compression coil spring 61 as the backlash preventing biasing member) biases the valve shaft holder 30 toward the guide bush 20 (i.e., biases the valve shaft holder 30) even when the valve element 14 is located near the lowermost position (the origin position), in other words, even in a low flow rate region where the valve opening degree is small (the valve opening degree is equal to or smaller than a predetermined valve opening degree).

In this example, as in the fourth embodiment, the intermediate large diameter portion 12 of the valve shaft 10 is also provided so as to extend into the valve chamber 40a of the valve body 40 through the insertion hole 43 provided in the top portion of the valve chamber 40a of the valve body 40.

In the electrically operated valve 5 of the present embodiment, in contrast to the electrically operated valves 1 to 4 of the first to fourth embodiments, the lower surface side of the movable screw portion 33 of the valve shaft holder 30 is brought into contact with (pressed against) the upper surface side of the fixed screw portion 23 of the guide bush 20 by the urging force (of) the compression coil spring 61 (return spring 75) in both the forward flow state and the reverse flow state, but it is obvious that the present embodiment can also obtain the same operational effects as the electrically operated valve 1 of the first embodiment.

In the motor-operated valve 5 of the present embodiment, the return spring 75 as a return member for preventing the thread engagement and disengagement between the fixed screw portion 23 and the movable screw portion 33 in the screw feeding mechanism 28 and the compression coil spring 61 as a biasing member for preventing backlash can be shared, and therefore, an effect of reducing the number of components can be obtained.

In the first to fifth embodiments, in order to alleviate the impact when the valve body 14 is positioned (at the original position) with respect to the valve seat portion 46a, a compression coil spring (a biasing member for biasing in the valve closing direction) 60 is compression-fitted between a step surface (upward) formed between the upper small diameter portion 11 and the intermediate large diameter portion 12 of the valve shaft 10 and the lower surface of the top portion 32 of the valve shaft holder 30, but as shown in fig. 8 (fig. 8 shows a motor-operated valve 5A as a modification of the motor-operated valve 5 of the fifth embodiment), the compression coil spring 60 may be omitted as long as the valve body 14 can be positioned with respect to the valve seat portion 46 a.

Claims

1. An electrically operated valve comprising:

a valve shaft provided with a valve core; a valve body provided with a valve port orifice having a valve seat portion that is separated from or close to the valve body, and formed with a valve chamber into which fluid is introduced and discharged; a motor having a rotor coupled to the valve shaft and a stator for rotating the rotor; a screw feed mechanism that is configured by a fixed screw portion provided on the valve body side and a movable screw portion provided on the valve shaft side, and that raises and lowers the valve body of the valve shaft relative to the valve seat portion of the valve body in accordance with rotational driving of the rotor; and a lower stopper mechanism for restricting a rotational drop of the valve shaft,

wherein a clearance is formed between the valve body and the valve seat portion when the valve body is located at the lowermost position by the lower stopper mechanism, and fluid flows in both a forward direction from the valve chamber to the valve port orifice and a reverse direction from the valve port orifice to the valve chamber,

a backlash prevention biasing member that biases the movable screw portion in the screw feed mechanism in a lifting direction with respect to the fixed screw portion such that an upper surface of the movable screw portion abuts against a lower surface of the fixed screw portion or such that a lower surface of the movable screw portion abuts against an upper surface of the fixed screw portion, regardless of a direction of flow of the fluid, at least when the valve body is located at a lowermost position,

the backlash preventing biasing member is set to,

the valve body is configured such that an urging force thereof acts in a low flow rate region in which a valve opening degree of the valve body with respect to the valve seat portion is equal to or smaller than a predetermined valve opening degree, the urging force does not act after switching from the low flow rate region to a large flow rate region, and the urging force is after reaching an inflection point of a flow rate at an intermediate opening degree of the valve opening degree after switching from the low flow rate region to the large flow rate region.

2. An electrically operated valve comprising:

a valve shaft provided with a valve core;

a valve shaft holder coupled and fixed to the valve shaft;

a guide bush in which the valve shaft is inserted in a state of being relatively movable and rotatable in an axial direction;

a valve body provided with a valve port orifice having a valve seat portion that is separated from or close to the valve body, and a valve chamber in which a fluid is introduced and discharged, and the guide bush is fixed to the valve body;

a motor having a rotor coupled to the valve shaft holder and a stator for rotating the rotor so as to rotate the valve shaft holder with respect to the guide bush;

a screw feed mechanism that is configured by a fixed screw portion formed in the guide bush and a movable screw portion formed in the valve shaft holder, and that raises and lowers the valve body of the valve shaft relative to the valve seat portion of the valve body in accordance with rotational driving of the rotor; and

a lower stopper mechanism including a fixed stopper body provided to a lower stopper having a female screw portion screwed to the fixed screw portion of the guide bush and a movable stopper body provided to the valve shaft holder to restrict a rotational drop of the valve shaft holder,

a backlash prevention biasing member that biases the valve shaft holder in an up-and-down direction with respect to the guide bush such that an upper surface of the movable screw portion of the screw feed mechanism abuts against a lower surface of the fixed screw portion or such that a lower surface of the movable screw portion of the screw feed mechanism abuts against an upper surface of the fixed screw portion, regardless of a flow direction of the fluid, at least when the valve body is located at the lowermost position,

the backlash preventing biasing member is set to,

3. Electrically operated valve according to claim 2,

the backlash preventing biasing member is interposed between the valve body and the valve shaft.

4. Electrically operated valve according to claim 3,

the backlash preventing biasing member is disposed around the valve shaft in the valve chamber.

5. Electrically operated valve according to claim 3,

the backlash preventing biasing member is disposed inside the guide bush.

6. Electrically operated valve according to claim 2,

the backlash prevention biasing member is interposed between the guide bush and the valve shaft.

7. Electrically operated valve according to any of claims 3 to 6,

a valve-closing-direction urging member that urges the valve element of the valve shaft in a valve closing direction is interposed between the valve shaft and the valve shaft holder,

the urging force of the backlash preventing urging member is smaller than the urging force of the urging member in the valve closing direction.

8. Electrically operated valve according to claim 2,

the backlash preventing biasing member is interposed between the lower stopper and the valve shaft holder.

9. Electrically operated valve according to claim 8,

the backlash preventing biasing member is disposed in an annular mounting groove provided in the lower stopper.

10. Electrically operated valve according to claim 9,

a valve-closing-direction urging member that urges the valve element of the valve shaft in the valve closing direction is interposed between the valve shaft and the valve shaft holder.

11. Electrically operated valve according to claim 2,

a housing is coupled and fixed to the valve main body, the rotor is rotatably inserted into the housing, and the stator is externally fitted to the housing,

the backlash preventing biasing member is interposed between the housing and the valve shaft holder.

12. Electrically operated valve according to claim 11,

the backlash prevention biasing member is used as a restoring member that biases the valve shaft holder toward the guide bush to prevent the thread engagement of the fixed thread portion and the movable thread portion in the thread feeding mechanism.

13. Electrically operated valve according to claim 11 or 12,