JP6676432B2 - Electric valve and method of assembling the same - Google Patents

Description

  The present invention relates to a motor-operated valve that is incorporated and used as a flow control valve or the like in a refrigeration cycle of an air conditioner, a refrigerator, or the like, and in particular, a valve body is at a lowest position (normally a fully closed state). The present invention also relates to a valve-closing-less type electric valve in which a gap of a predetermined size is formed between the valve and a valve seat, and a method of assembling the valve.

  As this type of electrically operated valve, for example, a valve stem, a guide stem having a cylindrical portion into which the valve stem is inserted, and a cylindrical stem held and fixed to the lower end of the valve stem and inserted into the guide stem A valve holder and a coil spring which is inserted into the valve holder so as to be axially movable and relatively rotatable with respect to the valve shaft, and is attached downward by a coil spring compressed between the valve shaft and the valve shaft. A valve body that is urged and locked by the valve holder, and has a valve seat portion to which the valve body comes and goes, and is joined to the valve body to which the guide stem is attached and fixed; A can, a rotor disposed on the inner periphery of the can, a rotor holder connecting the rotor and the valve shaft via a coupling member externally fitted and fixed to an upper end of the valve shaft, and the rotor Formed on the rotor holder so that the engaging portion provided on the A concave portion, a stator disposed on the outer periphery of the can for rotating the rotor, an internal thread member disposed on the inner periphery of the cylindrical portion of the guide stem, and a fixing formed on the inner periphery of the internal thread member. A screw feed mechanism comprising a screw part and a movable screw part formed on the outer periphery of the valve shaft for moving the valve body into and out of contact with the valve seat part; and a screw feed mechanism disposed on the outer periphery of the cylindrical part of the guide stem. A stopper mechanism for restricting rotation of the rotor in the vertical direction. The stopper mechanism abuts the spiral fixed stopper having an upper locking portion and a lower locking portion, and the upper locking portion. A ring-shaped or helical shape which is provided with a first abutting portion which is locked by being locked and a second abutting portion which is locked by being brought into contact with the lower locking portion, and which is incorporated in a spiral portion of the fixed stopper. Slider, and the slider is When the rotor rotates, the first contact portion is pushed by a pushing portion provided on the rotor, and the first contact portion is moved to the upper locking portion, and the second contact portion is moved. Is moved up and down while rotating until it comes into contact with the lower locking portion, and at the origin position where the second contact portion of the slider comes into contact with the lower locking portion and is stopped. It is known that a gap having a predetermined size is formed between the valve body and the valve seat portion (for example, see Patent Document 1).

  In the motor-operated valve having the configuration as described above, even when the valve body is at the lowest position (usually in a fully closed state), a gap of a predetermined size is formed between the valve body and the valve seat portion. Compared to a normal valve-closing type electric valve, it is possible to reliably prevent the valve body from biting into the valve seat portion, and when using the electric valve for an air conditioner, there is an advantage that it is possible to prevent an operation failure due to burning of the compressor. .

Japanese Patent No. 5164579

  By the way, in the conventional valve-closing-type electric valve as described above, the first conduit for refrigerant input / output is provided at one side of the valve chamber of the valve body, and the second conduit for refrigerant input / output is provided at the lower part of the valve chamber. Are connected and fixed by brazing or the like, respectively. Fluid (refrigerant) flows in one direction (positive direction) from the first conduit to the second conduit via the valve chamber, and the first conduit from the second conduit via the valve chamber. Backflow (screw play) is inevitable in the screw feed mechanism (between the fixed screw part and the movable screw part), which flows in the other direction (reverse direction) toward When 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 is urged by the pressure of the fluid, and the valve element is moved to the valve seat portion. On the other hand, it moves up and down by the backlash (screw play) (FIG. 7 ( ), (B) see).

  In the above-mentioned conventional electric valve, a valve body for controlling a flow rate of a fluid flowing through a valve port orifice is generally formed by an inverted truncated cone surface or an inverted conical surface (taper surface). Therefore, as described above, when the valve element moves up and down with respect to the valve seat in accordance with the change in the flow direction of the fluid, the valve element moves to the origin position (also referred to as the lowest position, and the number of pulses supplied to the motor becomes 0). When the fluid is in the pulse position, there is a problem that the flow rate (also referred to as zero pulse flow rate) of the fluid flowing through the valve port orifice changes before and after the flow direction of the fluid changes (see FIG. 8). ).

  In addition, in the above-described conventional motor-operated valve, usually, in determining the origin position of the valve body during assembly, a tapered surface of the valve body is brought into contact with a valve seat portion to form a reference position, and the valve body is moved from the reference position. The position of the origin of the valve body is determined by lifting the seat. That is, the tapered surface of the valve element is used as a reference plane for determining the origin position of the valve element (for details, see Patent Document 1 and the like). Therefore, the dimensional accuracy of the gap between the valve body and the valve seat portion at the origin position depends on the component accuracy (machining accuracy) of the tapered surface of the valve body, and the dimensional variation of the gap generally increases. In addition, there is a possibility that the flow characteristics (for example, the inflection point of the flow at the intermediate opening) vary.

  The present invention has been made in view of the above problems, and an object of the present invention is to suppress a flow rate change accompanying a change in a flow direction of a fluid (refrigerant) when a valve body is at a lowest position. And a method for assembling the same.

  Another object of the present invention is to provide a motor-operated valve capable of suppressing a dimensional variation of a gap formed between a valve body and a valve seat portion at an origin position, and, consequently, a variation in a flow characteristic. An object of the present invention is to provide an assembling method.

In order to solve the above problems, the motor-operated valve according to the present invention is provided with a valve shaft provided with a valve body, and a valve port orifice having a valve seat portion in which the valve body comes into contact with or separates from or approaches, A valve body in which a valve chamber through which fluid is introduced and led out is formed, a motor having a rotor connected to the valve shaft and a stator for rotating the rotor, and a fixing screw portion provided on the valve body side. A screw feed mechanism for moving the valve body of the valve shaft up and down with respect to the valve seat portion of the valve body in accordance with the rotational drive of the rotor, comprising a movable screw portion provided on the valve shaft side; A lower stopper mechanism for restricting the valve shaft from rotating downward. When the valve body is at the lowest position by the lower stopper mechanism, fluid flows from the valve chamber to the valve port orifice. Forward direction and the valve port The valve body is provided with a valve body-side straight portion having a constant outer diameter in the ascending and descending directions, and the valve seat portion is provided in the valve seat portion. A valve seat-side straight portion having a constant inner diameter in the elevating direction is provided, and a dimension larger than the orifice diameter of the valve port orifice and perpendicular to the elevating direction is provided above the valve body-side straight portion in the valve body. and valve body side abutting part is provided with a flat surface, said valve body, said valve body side abuts against the valve body-side contact part is provided at the contact portion and the plane, said valve by the lower stopper mechanism When the body is at the lowest position and when the fluid flows in the forward direction, a predetermined length shorter than the length of the valve body-side straight portion in the vertical direction between the valve body-side contact portion and the valve seat portion. Between the size of Is formed, and the valve body-side straight portion is connected below the valve body-side contact portion of the valve body, and a backlash portion between the fixed screw portion and the movable screw portion in the screw feed mechanism and the gap are provided. der least the combined length dimensions is, when the valve body by the lower stopper mechanism is in the lowest position, and at least a portion of the valve body side straight portion and at least a portion of the valve seat-side straight portion There has been characterized that you have been overlapped in the lifting direction.

In a preferred embodiment, the valve body side straight portion, Ru length der the combined size of the said backlash clearance.

  The valve seat portion and the valve port orifice are preferably formed in a part of the valve body.

  The valve seat portion and the valve port orifice are preferably formed in a seat member inserted and fixed in a fitting hole formed in a part of the valve body.

The method for assembling a motor-operated valve according to the present invention includes: a valve shaft provided with a valve element; a guide bush having a cylindrical portion into which the valve shaft is inserted so as to be relatively movable and relatively rotatable in an axial direction; A valve body having a valve opening orifice having a valve seat portion with which a valve body comes into contact with or close to or away from the valve body, a valve chamber into which a fluid is introduced and led out, and a valve body to which the guide bush is fixedly mounted; A valve shaft holder having a cylindrical portion into which a bush is inserted and a ceiling portion through which an insertion hole through which an upper end portion of the valve shaft is inserted, and a valve shaft holder connected and fixed to the valve shaft; A biasing member interposed between the valve shaft and the valve shaft holder for biasing in a valve direction; and a biasing member connected to the valve shaft holder to rotate the valve shaft holder with respect to the guide bush. Rotating the rotor and rotating the rotor And a fixed screw portion formed on the outer periphery of the guide bush and a movable screw portion formed on the inner periphery of the valve shaft holder, and the valve shaft is driven in accordance with the rotational driving of the rotor. A screw feed mechanism for raising and lowering the valve body with respect to the valve seat portion of the valve body; and A lower stopper mechanism comprising a fixed stopper body provided on a lower stopper having a female screw portion, and a movable stopper body provided on the valve shaft holder, and the valve body is moved to a lowermost position by the lower stopper mechanism. when in electric the flow body is from the positive direction as the valve port orifices toward the valve port orifices from the valve chamber to be flowed in both directions between the opposite direction toward the valve chamber Wherein the valve body of the motor-operated valve is provided with a valve body-side straight portion having a constant outer diameter in the elevating direction, and the valve seat portion has a valve seat side having a constant inner diameter in the elevating direction. A straight portion is provided, and a valve body-side abutting portion having a surface perpendicular to an elevating direction is provided above the valve body-side straight portion in the valve body, and the valve body is provided by the lower stopper mechanism. When in the lowest position and when the fluid is flowing in the forward direction, a gap of a predetermined size is formed in the elevating direction between the valve body-side contact portion and the valve seat portion, The valve body-side straight portion is connected below the valve body-side contact portion of the valve body, and has a length corresponding to the backlash between the fixed screw portion and the movable screw portion in the screw feed mechanism and the size of the gap. That's it, In the assembling method, in a state where the valve shaft and the valve shaft holder are not connected and fixed, the lower stopper is relatively rotatably screwed to the guide bush and arranged at a predetermined position, and the lower stopper mechanism is used. Positioning the valve stem holder at the lowermost position, lowering the valve body from the lowest position, and bringing the valve body-side contact portion into contact with the valve body; and A step of connecting and fixing a holder, and when the valve body is at the lowest position, at least a part of the valve body-side straight portion and at least a portion of the valve seat-side straight portion overlap in the elevating direction. By rotating the lower stopper at the predetermined position with respect to the guide bush by a predetermined rotation angle in the valve opening direction with respect to a position where the valve body side contact portion abuts on the valve body, It is characterized by a step of relatively non-rotatably coupled to Dobusshu.

  According to the present invention, when the valve element is at the lowest position, at least a part of the valve element-side straight part provided on the valve element and at least a part of the valve seat-side straight part provided on the valve seat part. The dimensions and shape of each part are set so as to overlap in the vertical direction. More specifically, when the valve element is farthest from the valve seat portion when the valve element is at the lowest position (when the fluid flows in the opposite direction), at least a part of the valve element side straight portion and the valve seat side At least a part of the straight portion is configured to overlap in the elevating direction. Therefore, when the valve element is at the lowest position, even if the valve element moves up and down with respect to the valve seat in response to a change in the flow direction of the fluid, the flow rate of the fluid flowing through the valve port orifice (0 pulse flow rate) ) Changes continuously. For example, as compared with a conventional motor-operated valve in which a valve body for controlling a flow rate of a fluid (refrigerant) flowing through a valve port orifice has a tapered surface, the valve body is at a lowermost position. , The change in the flow rate due to the change in the flow direction of the fluid (refrigerant) can be reliably suppressed.

  In addition, a valve body-side contact portion having a surface perpendicular to the elevating direction is provided above the valve body-side straight portion of the valve body. The contact portion of the valve body is brought into contact with the valve body when lowered from the lowered position. That is, the contact portion (the surface perpendicular to the vertical direction) provided above the valve body-side straight portion of the valve body is used as a reference surface for determining the origin position of the valve body. The dimensional accuracy of the gap between them basically depends on the component accuracy (machining accuracy) of the contact portion of the valve element. For this reason, for example, compared with a conventional motor-operated valve in which the tapered surface of the valve element is used as a reference plane for determining the origin position of the valve element, the dimensional variation of the gap and, consequently, the flow rate characteristics (for example, the change in the flow rate at an intermediate opening degree). Variations in (curve points) can be effectively suppressed. In addition, since the above-mentioned valve body side straight portion (the length in the elevating direction) is determined with reference to the contact portion (reference surface), the dimensional accuracy of the valve body side straight portion can be ensured. Variations in characteristics (e.g., inflection point of flow rate at intermediate opening) can be suppressed more effectively.

1 is a longitudinal sectional view showing an embodiment of a motor-operated valve according to the present invention. FIG. 2 is an enlarged longitudinal sectional view of a main part of the motor-operated valve shown in FIG. 1, in which (A) shows a forward flow state and (B) shows a reverse flow state. The figure which shows an example of the flow characteristic of the motor-operated valve shown in FIG. The figure which shows the other example of the flow characteristic of the motor-operated valve shown in FIG. The principal part expansion longitudinal cross-sectional view which expands and shows the principal part of the other example of the electrically operated valve shown in FIG. A top view and a partially enlarged longitudinal cross-section for explaining a process of rotating a lower stopper with respect to a guide bush in a process of setting an origin position (lowest position) of a valve body in a process of assembling the motor-operated valve shown in FIG. FIG. It is a principal part enlarged longitudinal sectional view which expands and shows the principal part of the conventional electrically operated valve, (A) is a figure which shows a forward flow state, (B) is a figure which shows a reverse flow state. The figure which shows the flow characteristic of the conventional motor-operated valve.

  Hereinafter, embodiments of a motor-operated valve according to the present invention and an assembling method thereof will be described with reference to the drawings. In each of the drawings, gaps formed between members, separation distances between members, and the like may be exaggerated for ease of understanding of the invention and for convenience of drawing. is there. Further, in this specification, descriptions indicating positions and directions such as up and down, left and right, etc. are based on the direction arrow display in FIG. 1 and do not indicate positions and directions in an actual use state.

  Further, in the present specification, the first conduit connected to the side of the valve chamber in the valve body is provided below the valve chamber through a valve chamber and a vertical valve port orifice formed at the bottom of the valve chamber. The direction toward the connected second conduit is referred to as “forward direction”, and the direction toward the first conduit from the second conduit via the valve port orifice and the valve chamber is referred to as “reverse direction”.

<Configuration and operation of motorized valve>
FIG. 1 is a longitudinal sectional view showing one embodiment of a motor-operated valve according to the present invention.

  The motor-operated valve 1 according to the illustrated embodiment mainly includes a valve shaft 10, a guide bush 20, a valve shaft holder 30, a valve body 40, a can 55, a stepping motor 50 including a rotor 51 and a stator 52, It includes a compression coil spring (biasing member) 60, a retaining member 70, a screw feed mechanism 28, and a lower stopper mechanism 29.

  The valve shaft 10 has, from the upper side, an upper small-diameter portion 11, an intermediate large-diameter portion 12, and a lower small-diameter portion 13. A fluid (refrigerant) flowing through the valve port orifice 46 is provided at the lower end of the lower small-diameter portion 13. ) Is integrally formed with a valve element 14 for controlling the flow rate.

  The valve body 14 has a cylindrical surface slightly smaller in diameter than the lower small-diameter portion 13 of the valve shaft 10 (from the upper side (the valve chamber 40a side)), as can be clearly understood from FIG. A constant angle (a fixed portion) 14s, an upper tapered surface portion 14t formed of an inverted frustoconical surface, and a control angle (an intersection angle between a line parallel to the central axis O of the valve body 14) formed by the upper tapered surface portion 14t. And a lower tapered surface portion 14u composed of a large inverted truncated conical surface.

  The length of the straight portion 14s in the elevating direction (vertical direction) is designed to be equal to or greater than the backlash (screw play) of the screw feed mechanism 28 (between the fixed screw portion 23 and the movable screw portion 33 constituting the screw feed mechanism 28). (Details will be described later).

  Further, above the straight portion 14s of the valve body 14 (connected to the straight portion 14s), a terrace formed between the lower small diameter portion 13 of the valve shaft 10 and (the straight portion 14s thereof). An annular flat surface (horizontal surface) (valve body side contact portion) 14f constituted by a surface is provided. This annular flat surface 14f is a surface perpendicular to the elevating direction, and when the motor-operated valve 1 is assembled, the valve element 14 is moved from the lowest position at the origin position (lowest position) of the valve element 14. When lowered, it is a reference surface that is brought into contact with the valve body 40 (specifically, an annular flat surface 45f as a valve body-side contact portion formed on the upper surface of the bottom wall 45 of the valve body 40). (Details will be described later).

  The guide bush 20 includes a cylindrical portion 21 in which the valve shaft 10 (the intermediate large-diameter portion 12) is relatively movable (slidable) in the direction of the axis O and relatively rotatable around the axis O. It extends upward from the upper end of the cylindrical portion 21 and has an inner diameter larger than that of the cylindrical portion 21, and the upper end of the intermediate large-diameter portion 12 of the valve shaft 10 and the lower end of the upper small-diameter portion 11 are inserted therein. And an installation part 22. On the outer periphery of the cylindrical portion 21 of the guide bush 20, one of a screw feed mechanism 28 for raising and lowering the valve body 14 of the valve shaft 10 with respect to the valve seat portion 46a of the valve body 40 in accordance with the rotational driving of the rotor 51 is provided. A fixing screw portion (male screw portion) 23 to be constituted is formed. The lower portion of the cylindrical portion 21 (the portion below the fixing screw portion 23) has a large diameter and serves as a fitting portion 27 for fitting into a fitting hole 44 of the valve body 40. A lower stopper 25 is fixed to the fixing screw portion 23 (on the lower side of the valve shaft holder 30) by being screwed to the upper surface 27a of the fitting portion 27 with a predetermined gap h. A fixed stopper body 24, which constitutes one of a lower stopper mechanism 29 that regulates the downward movement of the valve shaft holder 30 (that is, the valve shaft 10 connected to the valve shaft holder 30), protrudes integrally with the outer periphery of the valve shaft 25. Has been established. As described later in detail, in the present embodiment, the upper surface 27a of the fitting portion 27 regulates the lower movement of the lower stopper 25 (in other words, the lower movement limit position or the lowermost movement position of the lower stopper 25). Is defined as a stopper portion.

  The valve shaft holder 30 includes a cylindrical portion 31 into which the guide bush 20 is inserted and a ceiling portion 32 through which an insertion hole 32a through which an upper end portion of the valve shaft 10 (the upper small diameter portion 11) is inserted. Have. On the inner periphery of the cylindrical portion 31 of the valve shaft holder 30, a movable screw portion (female screw portion) 33 which is screwed with the fixed screw portion 23 of the guide bush 20 to constitute the screw feed mechanism 28 is formed. A movable stopper 34, which constitutes the other of the lower stopper mechanism 29, is integrally provided at the lower end of the outer periphery of the cylindrical portion 31.

  Further, between the terrace surface formed between the upper small diameter portion 11 and the middle large diameter portion 12 of the valve shaft 10 and the lower surface of the ceiling portion 32 of the valve shaft holder 30, the upper small diameter of the valve shaft 10 is provided. The valve shaft 10 and the valve shaft holder 30 are urged in a direction in which the valve shaft 10 and the valve shaft holder 30 are separated in the ascending and descending direction (the direction of the axis O) so that the valve shaft 10 (the valve body 14) is always downward. A compression coil spring (biasing member) 60 for biasing (valve closing direction) is contracted.

  The valve body 40 is formed of a metal cylinder such as brass or SUS. The valve body 40 has a valve chamber 40a into which a fluid is introduced and discharged, and a first conduit 41a is connected and fixed to a first lateral opening 41 provided on a side of the valve chamber 40a by brazing or the like. An insertion hole through which the valve shaft 10 (the intermediate large-diameter portion 12) is relatively movable (slidable) in the direction of the axis O and relatively rotatable around the axis O in the ceiling of the valve chamber 40 a. A fitting hole 44 for fitting and fixing the lower portion (fitting portion 27) of the guide bush 43 and the lower portion 43 is formed, and a second vertical opening 42 provided in the lower portion of the valve chamber 40a is formed in the second opening 42. The two conduits 42a are connected and fixed by brazing or the like. A substantially frustoconical valve port orifice 46 having a valve seat portion 46a on the bottom wall 45 provided between the valve chamber 40a and the second opening 42 so that the valve element 14 comes in contact with or separates from the valve chamber 40a. Is formed, and the valve seat portion 46a is provided with a straight portion (valve seat side straight portion) 46s formed of a cylindrical surface (having a constant inner diameter in the vertical direction) (see FIG. 2).

  The inner diameter of the straight portion 46s is designed to be slightly larger than the straight portion 14s of the valve body 14 and smaller than the lower small-diameter portion 13 of the valve shaft 10.

  An annular flat surface (horizontal surface) (a valve body side contact portion) 45f around the valve port orifice 46 (valve seat portion 46a) on the upper surface of the bottom wall 45 of the valve body 40 is provided. Is a contact surface (reference surface) that is brought into flat contact with the annular flat surface 14f on the valve element 14 side when the original position of the valve element 14 at the time of assembling the motor-operated valve 1 (the lowest position) (FIG. Details will be described later).

  On the other hand, a flange-shaped plate 47 is fixed to the upper end of the valve body 40 by caulking or the like, and the lower end of a cylindrical can 55 with a ceiling is provided at a step provided on the outer periphery of the flange-shaped plate 47. Sealed and joined by butt welding.

  A rotor 51 is rotatably disposed inside the can 55 and outside the guide bush 20 and the valve shaft holder 30. Outside the can 55, a yoke 52a is provided to rotationally drive the rotor 51. A stator 52 including a bobbin 52b, a stator coil 52c, a resin mold cover 52d, and the like is arranged. A plurality of lead terminals 52e are connected to the stator coil 52c, and a plurality of lead wires 52g are connected to these lead terminals 52e via a substrate 52f. The plurality of lead wires 52g are arranged in the can 55 by exciting the stator coil 52c. The existing rotor 51 rotates around the axis O.

  The rotor 51 disposed in the can 55 is engaged and supported by the valve shaft holder 30, and the valve shaft holder 30 rotates (integrally) with the rotor 51.

  In detail, the rotor 51 has a double-pipe configuration including an inner cylinder 51a, an outer cylinder 51b, and a connection portion 51c that connects the inner cylinder 51a and the outer cylinder 51b at a predetermined angle around the axis O. A vertical groove 51d extending in the direction of the axis O (up and down direction) (for example, at an angular interval of 120 degrees around the axis O) is formed on the inner periphery of the inner cylinder 51a.

  On the other hand, on the outer periphery (upper half portion) of the valve shaft holder 30, a protruding ridge 30a extending vertically (for example, at an angular interval of 120 degrees around the axis O) is protruded, and a lower portion of the protruding ridge 30a is provided. On both sides, an upward locking surface (not shown) for supporting the rotor 51 is formed.

  The vertical groove 51d of the inner cylinder 51a of the rotor 51 engages with the ridge 30a of the valve shaft holder 30, and the lower surface of the inner cylinder 51a of the rotor 51 comes into contact with the locking surface of the valve shaft holder 30, whereby The rotor 51 is supported and fixed in a state where it is aligned with the valve shaft holder 30, and the valve shaft holder 30 is rotated together with the rotor 51 while supporting the rotor 51 in the can 55.

  Above the rotor 51 and the valve shaft holder 30, relative movement between the valve shaft holder 30 and the rotor 51 in the elevating direction is prevented (in other words, the rotor 51 is pressed downward against the valve shaft holder 30) and the valve is disposed. In order to connect the shaft 10 and the valve shaft holder 30, a push nut 71 externally fitted and fixed to an upper end portion of the valve shaft 10 (upper small diameter portion 11) by press-fitting, welding, or the like, and the push nut 71 and the rotor 51. And a rotor retainer 72 composed of a disc-shaped member having a centrally formed insertion hole 72a through which the upper end of the valve shaft 10 is inserted. ing. That is, the rotor 51 is sandwiched between the valve shaft holder 30 urged upward by the urging force of the compression coil spring 60 and the rotor retainer 72. The height (in the vertical direction) from the upper end of the valve shaft holder 30 to the locking surface is the same as the height (in the vertical direction) of the inner cylinder 51 a of the rotor 51, and the ceiling portion 32 of the valve shaft holder 30. ) Is in contact with the lower surface (flat surface) of the rotor retainer 72.

  In addition, the push nut 71 fixed to the upper end of the valve shaft 10 has the valve shaft holder 30 which moves too much upward with respect to the guide bush 20 during operation, and the fixing screw portion 23 of the guide bush 20 and the valve. In order to prevent the screw engagement with the movable screw portion 33 of the shaft holder 30 from coming off, a return spring 75 composed of a coil spring for urging the valve shaft holder 30 toward the guide bush 20 is provided.

  In the motor-operated valve 1, for example, the valve body 14 is moved to the lowest position (origin position) in order to prevent the valve body 14 from biting the valve seat portion 46 a and to ensure controllability in a low flow rate region. At one time, a gap of a predetermined size is formed between the valve body 14 and the valve seat 46a. In this example, between the straight portion 14s of the valve body 14 and the straight portion 46s of the bottom wall 45 of the valve body 40, and the annular flat surface 14f connected to the straight portion 14s and the annular flat surface 45f connected to the straight portion 46s. And a gap of a predetermined size is formed between them.

  In the electric valve 1 having such a configuration, when the rotor 51 is rotated by energizing the stator 52 (the stator coil 52c thereof), the valve shaft holder 30 and the valve shaft 10 are rotated integrally therewith. At this time, the valve shaft 10 is moved up and down along with the valve element 14 by the screw feed mechanism 28 including the fixed screw part 23 of the guide bush 20 and the movable screw part 33 of the valve shaft holder 30. The gap (lift amount, valve opening) between the valve seat 46a and the valve seat 46a is increased or decreased to adjust the flow rate of a fluid such as a refrigerant. Further, even when the movable stopper body 34 of the valve shaft holder 30 and the fixed stopper body 24 of the lower stopper 25 fixed to the guide bush 20 are in contact with each other, and the valve body 14 is at the lowest position, the valve body 14 and the valve seat are not moved. Since a gap (a required lift amount at the time of closing the valve) is formed with the portion 46a, a predetermined flow rate is secured (see FIG. 3).

  By the way, in the motor-operated valve 1 of the present embodiment, the fluid (refrigerant) flows bidirectionally, specifically, from the first conduit 41a (first opening 41) through the valve chamber 40a and the valve port orifice 46 to the second conduit. 42a (second opening 42) (i.e., from side to bottom) (hereinafter, this state is referred to as a forward flow state), and from the second conduit 42a (second opening 42) to the valve port orifice 46 and the valve chamber. It flows in both directions, that is, the direction toward the first conduit 41a (the first opening 41) via the 40a (that is, downward → lateral direction) (hereinafter, this state is referred to as a reverse flow state). The pressure of the fluid urges the valve element 14 downward in the forward flow state, and urges the valve element 14 upward in the reverse flow state. In the screw feed mechanism 28 that raises and lowers the valve element 14 with respect to the valve seat 46a, the movable screw part 33 of the valve shaft holder 30 to which the valve element 14 (the valve shaft 10) is connected and the valve body 40 are connected and fixed. A backlash (screw play) exists between the guide screw 20 and the fixing screw portion 23 of the guide bush 20. Therefore, in the forward flow state, the valve element 14 is moved downward (until the lower surface side of the movable screw portion 33 of the valve shaft holder 30 contacts the upper surface side of the fixed screw portion 23 of the guide bush 20) ( In the reverse flow state, the valve element 14 is in contact with the upper surface side of the movable screw portion 33 of the valve shaft holder 30 and the lower surface side of the fixed screw portion 23 of the guide bush 20 (see FIG. 2A). (The state shown in FIG. 2B). That is, when 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 moves up and down with respect to the valve seat portion 46a by the backlash.

  Here, in the present embodiment, when the valve element 14 is at the lowest position, at least a part of the straight part 14s on the valve element 14 side and at least a part of the straight part 46s on the valve seat part 46a move up and down. The dimensions and shapes of the respective parts are set so as to overlap (lap) in (vertical direction). More specifically, the length of the straight portion 14s in the vertical direction (vertical direction) is designed to be equal to or greater than the backlash of the screw feed mechanism 28 (between the fixed screw portion 23 and the movable screw portion 33 constituting the screw feed mechanism 28), When the valve body 14 is farthest from the valve seat portion 46a when the body 14 is at the lowest position (in a reverse flow state), the lower portion of the straight portion 14s on the valve body 14 side and the straight portion on the valve seat 46a side The upper portion of the portion 46s is overlapped by the overlapping amount (lap amount) Lmin in the vertical direction (the state shown in FIG. 2B).

  In this case, in the forward flow state, the overlapping amount Lmax between the straight portion 14s on the valve body 14 side and the straight portion 46s on the valve seat portion 46a in the elevating direction is equal to the overlapping amount Lmin. The backlash is added (the state shown in FIG. 2A).

  Therefore, as shown in FIG. 3, when the valve element 14 is at the lowest position, the flow direction of the fluid changes from the forward direction to the reverse direction, or from the reverse direction to the forward direction, and the valve element 14 becomes a valve seat. Even if it moves up and down with respect to the portion 46a, the passing flow rate (zero pulse flow rate) of the fluid flowing through the valve port orifice 46 continuously changes. For example, the passing flow rate of the fluid (refrigerant) flowing through the valve port orifice is reduced. Compared to a conventional motor-operated valve in which the valve body to be controlled is a tapered surface, it is possible to reliably suppress a change in the flow rate due to a change in the flow direction of the fluid (refrigerant) when the valve body 14 is at the lowest position. it can.

  In the present embodiment, an annular flat surface (valve body side contact portion) 14f having a surface perpendicular to the elevating direction is provided above the straight portion 14s of the valve body 14, and the bottom wall of the valve body 40 is provided. An annular flat surface (abutment portion on the valve body side) 45f is provided around the valve opening orifice 46 (valve seat portion 46a) on the upper surface of the 45, so that the valve body 14 can be located at the origin position (lowest position) at the time of assembly. When the valve element 14 is lowered from the lowermost position, the annular flat surface 14f of the valve element 14 is brought into contact with the annular flat surface 45f of the valve body 40. That is, the annular flat surface 14f provided above the straight portion 14s of the valve element 14 and the annular flat surface 45f of the valve body 40 are used as reference planes for determining the origin of the valve element 14. The dimensional accuracy of the gap with the seat portion 46a basically depends on the component accuracy (machining accuracy) of the annular flat surface 14f of the valve element 14 (described in detail later). For this reason, for example, compared with a conventional motor-operated valve in which the tapered surface of the valve element is used as a reference plane for determining the origin position of the valve element, the dimensional variation of the gap and, consequently, the flow rate characteristics (for example, the change in the flow rate at an intermediate opening degree). Variations in (curve points) can be effectively suppressed. Further, since the length of the straight portion 14s on the valve body 14 side in the elevating direction is determined based on the annular flat surface 14f (reference surface), the dimensional accuracy of the straight portion 14s on the valve body 14 side can be secured. Also from this point, it is possible to more effectively suppress the variation of the flow characteristics (for example, the inflection point of the flow at the intermediate opening).

  In the example shown in FIG. 3, in the reverse flow state in which the valve element 14 is urged upward, the lower part of the straight part 14s on the valve element 14 side and the upper part of the straight part 46s on the valve seat part 46a side. The upper portion and the lower portion overlap each other by a predetermined overlap amount Lmin in the vertical direction. For example, as shown in FIG. The dimensions and shape of each part may be set so that the upper end of the straight part 46s on the sheet part 46a side coincides (that is, the overlapping amount Lmin in the elevating direction is set to 0). In this case, in the forward flow state, the overlapping amount Lmax of the straight portion 14s on the valve body 14 side and the straight portion 46s on the valve seat portion 46a in the elevating direction corresponds to the backlash of the screw feed mechanism 28.

  Further, in the above embodiment, the configuration is such that the annular flat surface 14f on the valve body 14 side and the annular flat surface 45f on the valve body 40 side abut on each other. One or both of the annular flat surface 14f on the 14 side and the annular flat surface 45f on the valve body 40 side may have a projecting cross section.

  Further, in the above embodiment, the valve port orifice 46 having the valve seat portion 46a provided with the straight portion 46s is formed on the bottom wall 45 of the valve body 40. For example, as shown in FIG. A seat member 48 having a valve port orifice 46 having a valve seat portion 46a provided with a straight portion 46s is formed by cutting or the like, and the seat member 48 is fitted to a bottom wall 45 of the valve body 40 by fitting. The holes 49 may be inserted and fixed. In this case, the periphery of the valve port orifice 46 (valve seat portion 46a) on the upper surface of the seat member 48 is an annular flat surface (horizontal surface) (abutment portion on the valve body side) 48f. The contact surface (reference surface) which is brought into contact with the annular flat surface 14f on the valve element 14 side in a plane when the origin position (lowest descent position) of 14 is set.

  As shown in FIG. 5, by using the seat member 48 which is a separate component from the valve body 40, the component accuracy of the seat member 48, particularly the dimensional accuracy of the straight portion 46s and the annular flat surface 48f can be improved. In addition, variations in flow characteristics can be suppressed more effectively.

<Assembly method of motorized valve>
An example of the assembling process of the electric valve 1 described above, in particular, an example of the process of setting the origin position (lowest descent position) of the valve element 14 will be outlined with reference to FIGS. 1 and 2. 20, the lower stopper 25, the compression coil spring 60, the valve shaft holder 30, the rotor 51, the valve body 40 and the like are assembled. At this time, the lower stopper 25 is screwed so as to be rotatable relative to the guide bush 20. 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 an interval from the stopper 27a. Next, the valve element 14 provided at the lower end of the valve shaft 10 contacts the valve seat portion 46a (that is, the annular flat surface 14f of the valve element 14 contacts the annular flat surface 45f of the valve body 40), and the compression coil The spring 60 is slightly compressed, and the movable stopper 34 of the valve shaft holder 30 and the fixed stopper 24 of the lower stopper 25 abut, and the lower stopper 25 (the lower surface) abuts the stopper 27a of the guide bush 20. Until the valve shaft holder 30, the rotor 51, and the valve shaft 10 are rotated by using 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, Let it. Then, the valve shaft holder 30 is positioned at the lowermost position, and the valve element 14 is lowered from the lowermost position, so that the annular flat surface 14f contacts the annular flat surface 45f of the valve body 40. In this state, the rotor retainer 72 is fitted into the upper end of the valve shaft 10 and the push nut 71 is externally fitted and fixed by press fitting, welding, or the like.

  Next, from the above-described state, an assembly in which the valve shaft 10, the valve shaft holder 30, the rotor 51, the retaining member 70 (the push nut 71 and the rotor retainer 72) and the like are integrated, the screw feed mechanism 28 is mounted. After being removed from the guide bush 20 while being rotated while being used, the lower stopper 25 is rotated by a predetermined rotation angle with respect to the guide bush 20 in the valve opening direction (in the illustrated example, counterclockwise in plan view). Then, the lower stopper 25 is connected to and fixed to the guide bush 20 (the fixing screw portion 23 thereof) by welding, welding, bonding, or the like so that the lower stopper 25 cannot rotate relative to each other. Assemble to 20. As a result, the position of the lower stopper 25 with respect to the guide bush 20 of the fixed stopper body 24 changes, so that the movable stopper body 34 of the valve shaft holder 30 and the fixed stopper body 24 of the lower stopper 25 abut, and the valve shaft holder 30 is moved. Even when the valve element 14 is at the lowermost position (that is, when the valve element 14 is at the lowermost position), a gap of a predetermined size between the valve element 14 and the valve seat portion 46a (the vertical direction in the forward flow state). Is formed (a gap having a dimension of H) (see FIG. 2A). At this time, the amount of overlap Lmax between the straight portion 14s on the valve element 14 side and the straight portion 46s on the valve seat portion 46a in the elevating direction is, for example, the backlash of the screw feed mechanism 28. After the assembly is lifted and removed from the guide bush 20, the lower stopper 25 is rotated by a predetermined rotation angle in the valve opening direction with respect to the guide bush 20, and the lower stopper 25 is welded and welded to the guide bush 20. Although it has been described that the assembly is fixed and connected to the guide bush 20 so as to be relatively non-rotatable by bonding or the like, the lower stopper 25 is moved relative to the guide bush 20 by a predetermined rotation angle in the valve opening direction only by raising the assembly with respect to the guide bush 20. If the gap can be formed so that the lower stopper 25 can be rotated and the lower stopper 25 can be connected and fixed to the guide bush 20 so as to be relatively non-rotatable by welding, welding, bonding, or the like, the assembly is removed from the guide bush 20. No need to remove.

  When a backlash-less (non-backlash) type screw portion is used for the female screw portion 26 of the lower stopper 25 and the fixing screw portion (male screw portion) 23 of the guide bush 20, the valve body 14 and the valve seat portion 46a are connected to each other. The dimension H of the gap formed therebetween in the elevating direction coincides or substantially coincides with the gap h between (the lower surface of) the lower stopper 25 and the stopper 27a of the guide bush 20. However, in general, a backlash (play or backlash) is provided in the screw portion. Therefore, when the lower stopper 25 is brought into contact with the stopper portion 27a of the guide bush 20 and tightened as in the above-described embodiment, and then rotated (loose) in the valve opening direction to perform the origin position of the valve body 14, At the initial stage of rotation, the lower stopper 25 rotates while being in contact with the stopper portion 27a of the guide bush 20 (that is, without rising), so that the dimension H does not always match the gap h.

  Specifically, as can be well understood with reference to FIG. 6, the rotation angle of the backlash between the female screw portion 26 of the lower stopper 25 and the fixing screw portion 23 of the guide bush 20 is represented by θb [°] (FIG. In the illustrated example, when the angle is set to about 180 °, the lower stopper 25 is brought into contact with the stopper 27a of the guide bush 20 and tightened (in this state, the female screw portion of the lower stopper 25) in the above-described origin position setting step. When the lower stopper 25 is rotated (loosen) in the valve opening direction from the upper surface side of 26 and the lower surface side of the fixed screw portion 23 of the guide bush 20), the rotation angle θb [°] of the backlash is obtained. Then, (the lower surface of) the lower stopper 25 keeps contacting with the stopper portion 27a of the guide bush 20 due to its own weight ((1) to (3) in FIG. 6). However, since the lower stopper 25 itself rotates, the rotational position of the fixed stopper body 24 provided on the lower stopper 25 changes.

  It is assumed that the lower stopper 25 is fixed to the guide bush 20 within the range of the rotation angle θb [°] corresponding to the backlash, and the valve shaft holder 30 is lowered using the screw feed mechanism 28 while rotating. When the movable stopper body 34 and the fixed stopper body 24 of the lower stopper 25 are brought into contact with each other, the lowermost movement position of the valve shaft holder 30 gradually increases in accordance with the amount of rotation of the lower stopper 25. For example, the rising amount Hb of the lowermost position of the valve shaft holder 30 at the time of backlash offset is p × θb / 360, where p is the screw pitch (interval between screw threads) of the female screw portion 26 of the lower stopper 25. It is defined ((3) in FIG. 6).

  After the backlash is canceled (after the rotation angle of the lower stopper 25 reaches the rotation angle θb [°] of the backlash) (in this state, the lower surface side of the female screw portion 26 of the lower stopper 25 and the fixing screw of the guide bush 20) When the lower stopper 25 is further rotated in the valve opening direction, the lower stopper 25 starts to rise while rotating, and a gap is formed between the lower stopper 25 and the stopper portion 27a of the guide bush 20. h is formed.

  Finally, if the lower stopper 25 is fixed to the guide bush 20 by rotating in the valve opening direction by the rotation angle θ [°] from the state in which the lower stopper 25 is brought into contact with the stopper portion 27 a of the guide bush 20 and tightened, Since the lowermost position of the holder 30 rises by the rising amount H defined by p × θ / 360, when the valve shaft holder 30 is at the lowest moving position (that is, when the valve element 14 is at the lowest position). ), A gap having a predetermined dimension H is formed between the valve element 14 and the valve seat portion 46a in the vertical direction (in the forward flow state) (see FIG. 2A). On the other hand, between the lower stopper 25 and the stopper portion 27a of the guide bush 20, a gap h obtained by subtracting the backlash from the rising amount H, that is, a gap h defined by p × (θ−θb) / 360. Is formed.

  In the illustrated embodiment, a gap h is formed between the lower stopper 25 and the stopper 27a of the guide bush 20 by rotating the lower stopper 25 beyond the rotation angle θb [°] of the backlash. However, when the dimension in the elevating direction of the gap formed between the valve body 14 and the valve seat portion 46a is set to be equal to or smaller than the above Hb, the lower stopper 25 is within the rotation angle θb [°] of the backlash. Therefore, no gap is formed between the lower stopper 25 and the stopper portion 27a of the guide bush 20, and the (lower surface of) the lower stopper 25 remains in contact with the stopper portion 27a of the guide bush 20. .

  In the above-described embodiment, the state in which the lower stopper 25 is brought into contact with the stopper portion 27a of the guide bush 20 and tightened is the reference state for the rotation of the lower stopper 25 in the valve opening direction. Needless to say, the fastening state of the lower stopper 25 and the position in the vertical direction are not limited to the illustrated embodiment. For example, the reference state of the lower stopper 25 may be any state within the range of the rotation angle corresponding to the backlash shown in (1) to (3) of FIG. The lower stopper 25 does not need to be in contact with the stopper 27a of the guide bush 20 in its reference state. For example, as shown in (4) of FIG. May be set as the reference state. When the lower stopper 25 is separated from the stopper portion 27a of the guide bush 20 (is not in contact with the stopper portion 27a), the backlash does not exist. The dimension H in the elevating direction of the gap formed between the sheet stopper 46a and the sheet portion 46a is smaller than the gap h between (the lower surface of) the lower stopper 25 and the stopper portion 27a of the guide bush 20 (in other words, the lower stopper 25 and the guide The gap h in the vertical direction of the stopper 27a of the bush 20 becomes larger than the dimension H).

  In the motor-operated valve 1 assembled by such an assembling method, as described above, when the rotor 51 is rotated by energizing the stator 52 (the stator coil 52c thereof), the valve shaft holder 30 and the valve shaft 10 are integrally formed therewith. It is rotated. At this time, the valve shaft 10 is moved up and down along with the valve element 14 by the screw feed mechanism 28 including the fixed screw part 23 of the guide bush 20 and the movable screw part 33 of the valve shaft holder 30. The gap (lift amount, valve opening) between the valve seat 46a and the valve seat 46a is increased or decreased to adjust the flow rate of a fluid such as a refrigerant. Further, even when the movable stopper body 34 of the valve shaft holder 30 and the fixed stopper body 24 of the lower stopper 25 fixed to the guide bush 20 are in contact with each other, and the valve body 14 is at the lowest position, the valve body 14 and the valve seat are not moved. Since a gap (a required lift amount at the time of closing the valve) is formed with the portion 46a, a predetermined flow rate is secured (see FIG. 3).

  In the motor-operated valve 1 of the present embodiment, a lower stopper 25 having a female thread portion 26 having a screw pitch p is screwed into a predetermined position of the guide bush 20 so as to be relatively rotatable, and the lower stopper mechanism 29 moves the valve shaft holder 30 to the lowermost position. The valve body 14 is lowered from the lowermost position to bring the annular flat surface 14f of the valve body 14 into contact with the annular flat surface 45f of the valve body 40. The lower stopper 25 at the predetermined position is rotated relative to the guide bush 20 by a predetermined rotation angle θ with respect to the guide bush 20 with reference to the position at which the 14 f abuts on the annular flat surface 45 f of the valve body 40. When the lower stopper mechanism 29 moves the valve shaft holder 30 to the lowermost position, the lower stopper mechanism 29 connects the valve body 14 and the valve seat portion 46a (specifically, Is formed between the annular flat surface 14f and the annular flat surface 45f), a gap whose dimension H in the vertical direction in the forward flow state is defined by p × θ / 360 is formed, At least a portion of the portion 14s and at least a portion of the straight portion 46s of the valve seat portion 46a overlap in the elevating direction. In other words, the lower stopper 25 is connected to the guide bush 20 so as not to rotate relative to the guide bush 20 after the lower stopper 25 is rotated in the valve opening direction, so that the lowermost position of the valve body 14 in the forward flow state, in other words, For example, a gap in the elevating direction between the valve body 14 and the valve seat portion 46a when the valve body 14 is at the lowest position is defined. That is, the dimensional accuracy of the gap between the valve element 14 and the valve seat portion 46a at the origin position is basically the same as that of the female screw portion 26 of the lower stopper 25 and the fixing screw portion 23 of the guide bush 20, which constitute the lower stopper mechanism 29. Since it depends on the dimensional accuracy, the dimensional variation of the gap can be suppressed, so that the controllability of the fluid (refrigerant) flow rate in a low flow rate region can be improved. Furthermore, the annular flat surface 14f provided above the straight portion 14s of the valve body 14 and the annular flat surface 45f of the valve body 40 are used as reference planes for determining the origin position at the time of assembling the valve body 14. The dimensional accuracy of the gap between the valve body 14 and the valve seat portion 46a basically depends on the component accuracy (processing accuracy) of the annular flat surface 14f of the valve body 14, and the dimensional variation of the gap, and thus, Variations in flow characteristics (eg, inflection point of flow at intermediate opening) can be effectively suppressed.

Reference Signs List 1 motorized valve 10 valve shaft 14 valve element 14f annular flat surface (contact part on valve element side)
14 s Valve body side straight part 20 Guide bush 21 Cylindrical part 23 Fixed screw part (male screw part)
28 Screw feed mechanism 29 Lower stopper mechanism 30 Valve shaft holder 33 Movable screw part (female screw part)
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 (Body Side Contact Part)
46 Valve port orifice 46a Valve seat portion 46s Valve seat side straight portion 47 Flange portion 48 Seat member 50 Stepping motor 51 Rotor 52 Stator 55 Can 60 Compression coil spring 70 Retaining locking member O Axis

Claims (5)

A valve shaft provided with a valve body, a valve body having a valve port orifice having a valve seat portion with which the valve body comes in contact with or close to or close to the valve body, and a valve body in which a valve chamber through which fluid is introduced and led out is formed; A motor having a rotor connected to a valve shaft and a stator for rotating the rotor, a fixed screw portion provided on the valve body side, and a movable screw portion provided on the valve shaft side; A screw feed mechanism for raising and lowering the valve body of the valve shaft with respect to the valve seat portion of the valve body in accordance with the rotational drive of the valve shaft, and a lower stopper mechanism for performing rotation lowering regulation of the valve shaft. ,
When the valve body is at the lowest position by the lower stopper mechanism, fluid flows in both directions: a forward direction from the valve chamber toward the valve port orifice and a reverse direction from the valve port orifice to the valve chamber. A motorized valve adapted to be
The valve body is provided with a valve body-side straight portion having a constant outer diameter in the elevating direction, and the valve seat portion is provided with a valve seat-side straight portion having a constant inner diameter in the elevating direction,
The upper side of the valve body side straight portion of the valve body, is provided with a valve body side contact portion having a vertical flat surface relative to the large dimensions and the lifting direction of the orifice diameter of the valve port orifices,
The valve body is provided with a valve body side contact portion that comes into contact with the valve body side contact portion in a plane,
When the valve body is at the lowest position and the fluid flows in the forward direction by the lower stopper mechanism, the valve body- side straight section is moved between the valve body-side contact portion and the valve seat in the up-and-down direction. A gap of a predetermined size shorter than the length of the portion is formed,
The valve body-side straight portion is connected below the valve body-side contact portion of the valve body, and has a length corresponding to the backlash between the fixed screw portion and the movable screw portion in the screw feed mechanism and the size of the gap. Ri der above is,
When the valve body by the lower stopper mechanism is in the lowest position, the Rukoto have at least a portion of the valve body side straight portion and at least a portion of the valve seat side straight portion is to overlap with the lifting direction Characterized electric valve.   The motor-operated valve according to claim 1, wherein the valve body-side straight portion has a length corresponding to a size of the backlash and the dimension of the gap. The valve seat and the valve port orifices, electric valve according to claim 1 or 2, characterized in that it is formed in a part of the valve body. The said valve seat part and the said valve port orifice are formed in the seat member inserted and fixed in the insertion hole formed in a part of the said valve main body, The Claims 1 or 2 characterized by the above-mentioned. Electric valve. A valve shaft provided with a valve element,
A guide bush having a cylindrical portion in which the valve shaft is inserted so as to be relatively movable and relatively rotatable in the axial direction;
A valve port orifice having a valve seat portion with which the valve body comes into contact with or close to or away from the valve body is provided, a valve chamber in which a fluid is introduced and led out is formed, and a valve body to which the guide bush is attached and fixed,
A valve shaft holder that has a cylindrical portion into which the guide bush is inserted and a ceiling portion through which an insertion hole through which the upper end of the valve shaft is inserted, and is fixedly connected to the valve shaft,
An urging member interposed between the valve shaft and the valve shaft holder to urge the valve body in a valve closing direction;
A motor having a rotor connected to the valve shaft holder and a stator for rotating the rotor, for rotating the valve shaft holder with respect to the guide bush;
The valve body comprises a fixed screw portion formed on an outer periphery of the guide bush and a movable screw portion formed on an inner periphery of the valve shaft holder, and the valve body of the valve shaft is moved in accordance with the rotation of the rotor. A screw feed mechanism for raising and lowering with respect to the valve seat portion of
A fixed stopper body provided on a lower stopper having a female screw portion screwed to the fixed screw portion of the guide bush for restricting rotation movement of the valve shaft holder, and a movable stopper provided on the valve shaft holder. A lower stopper mechanism comprising a stopper body,
When the valve body is at the lowest position by the lower stopper mechanism, fluid flows in both directions: a forward direction from the valve chamber toward the valve port orifice and a reverse direction from the valve port orifice to the valve chamber. A method for assembling a motor-operated valve,
The valve body of the motor-operated valve is provided with a valve body-side straight portion having a constant outer diameter in the elevating direction, and the valve seat portion is provided with a valve seat-side straight portion having a constant inner diameter in the elevating direction,
Above the valve body-side straight portion in the valve body, a valve body-side contact portion having a surface perpendicular to the elevating direction is provided,
When the valve body is at the lowest position and the fluid flows in the forward direction by the lower stopper mechanism, a predetermined size in the vertical direction between the valve body-side contact portion and the valve seat portion. Gap is formed,
The valve body-side straight portion is connected below the valve body-side contact portion of the valve body, and has a length corresponding to the backlash between the fixed screw portion and the movable screw portion in the screw feed mechanism and the size of the gap. More than
The assembling method is
In a state where the valve shaft and the valve shaft holder are not connected and fixed, the lower stopper is screwed into the guide bush so as to be relatively rotatable and arranged at a predetermined position, and the valve shaft holder is moved by the lower stopper mechanism. A step of positioning the valve body at the lowermost position, lowering the valve body from the lowest position, and bringing the valve body-side contact portion into contact with the valve body,
Connecting and fixing the valve shaft and the valve shaft holder,
When the valve element is at the lowermost position, the valve element-side abutting portion is configured such that at least a portion of the valve element-side straight portion and at least a portion of the valve seat-side straight portion overlap in the elevating direction. Rotating the lower stopper at the predetermined position with respect to the guide bush by a predetermined rotation angle in the valve opening direction with respect to the position in contact with the valve body, and connecting the lower stopper to the guide bush so as to be relatively non-rotatable. A method for assembling a motor-operated valve, comprising:

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