JP2020091038A - Motor-operated valve - Google Patents

Abstract

To provide a motor-operated valve that can suppress flow rate change due to change in a flow direction of fluid (refrigerant) when a valve element is in a lowermost descent position.SOLUTION: When a valve element 14 is in the lowermost descent position, at least part of a straight part 14s on a side of the valve element 14 overlaps on at least part of a straight part 46s on a side of a valve seat part 46a in an ascent/descent direction.SELECTED DRAWING: Figure 2

Description

The present invention relates to a motor-operated valve used as a flow control valve or the like incorporated in a refrigeration cycle of an air conditioner, a refrigerator, etc., and particularly, a valve body is at a lowest position (normally in a fully closed state). At times, the present invention relates to a valveless type electric valve in which a gap of a predetermined size is formed between the valve seat portion and the valve seat portion.

As this type of electrically operated valve, for example, a valve shaft, a guide stem having a cylindrical portion into which the valve shaft is inserted, and a cylindrical shape that is retained and fixed to the lower end portion of the valve shaft and inserted into the guide stem. A valve holder and a coil spring that is inserted into the valve holder so as to be relatively movable and relatively rotatable in the axial direction with respect to the valve shaft, and is attached downward by a coil spring that is compressed between the valve holder and the valve shaft. A valve body that is energized and that is retained and locked by the valve holder, a valve body that has a valve seat portion that contacts and separates the valve body, and that has the guide stem attached and fixed to the valve body, and is joined to the valve body. A can, a rotor disposed on the inner circumference of the can, a rotor holder that connects the rotor and the valve shaft via a coupling member that is externally fitted and fixed to the upper end of the valve shaft, and the rotor. A concave portion formed in the rotor holder so that the engaging portion provided in the can fit therein, a stator arranged on the outer circumference of the can for rotating the rotor, and a stator arranged on the inner circumference of the cylindrical portion of the guide stem. A screw for connecting and disconnecting the valve body to and from the valve seat portion, which includes a female screw member, a fixed screw portion formed on the inner circumference of the female screw member, and a movable screw portion formed on the outer circumference of the valve shaft. A feed mechanism and a stopper mechanism that is arranged on the outer periphery of the cylindrical portion of the guide stem and regulates the vertical movement of the rotor are provided, and the stopper mechanism has an upper locking portion and a lower locking portion. A spiral fixed stopper, a first abutment portion that abuts and abuts the upper engagement portion, and a second abutment portion that abuts and abuts the lower engagement portion are provided. And a slider having a ring shape or a spiral shape incorporated in a spiral portion of the fixed stopper, the slider being configured such that when the rotor is rotated, the first contact portion is provided by a pushing portion provided on the rotor. When pushed, the first contact portion is rotated and moved up and down until it contacts the upper locking portion and the second contact portion contacts the lower locking portion. At the origin position where the second abutment portion of the slider comes into contact with the lower engagement portion and is stopped, a gap of a predetermined size is formed between the valve body and the valve seat portion. The thing is known (for example, refer patent document 1).

In the motor-operated valve having the above-described configuration, even when the valve body is at the lowest position (normally in the fully closed state), a gap of a predetermined size is formed between the valve body and the valve seat portion. Compared with 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 in an air conditioner, there is an advantage that it is possible to prevent a malfunction due to seizure of the compressor. ..

Japanese Patent No. 5164579

By the way, in the conventional valve-less type motor-operated valve as described above, the first conduit for refrigerant inlet/outlet is provided at one side of the valve chamber of the valve body, and the second conduit for refrigerant inlet/outlet is provided at the lower portion of the valve chamber. Are respectively connected and fixed by brazing or the like, and the fluid (refrigerant) flows from the first conduit to the second conduit through the valve chamber in one direction (forward direction) and from the second conduit through the valve chamber to the first conduit. It is designed to be flowed in both directions toward the other direction (reverse direction), but backlash (screw backlash) is inevitable in the screw feed mechanism (between the fixed screw part and the movable screw part that make up the screw feed mechanism). Therefore, 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 body is biased by the pressure of the fluid and the valve body moves toward the valve seat portion. On the other hand, it moves up and down by the amount of the backlash (screw backlash) (see FIGS. 7A and 7B).

Further, in the above conventional electric valve, the valve body for controlling the flow rate of the fluid flowing through the valve orifice is usually formed by an inverted truncated cone surface or an inverted conical surface (tapered surface). Therefore, when the valve body moves up and down with respect to the valve seat portion in accordance with the change in the flow direction of the fluid as described above, the valve body moves to the origin position (also called the lowest position, where the number of pulses supplied to the motor is 0). There is a problem that the flow rate (also referred to as 0 pulse flow rate) of the fluid flowing through the valve orifice changes before and after the change in the flow direction of the fluid when in the pulse position (see FIG. 8). ).

In addition, in the above conventional motor-operated valve, when the origin of the valve body is set at the time of assembly, the tapered surface of the valve body is normally brought into contact with the valve seat portion to form a reference position, and the valve body is valved from the reference position. The valve is positioned at the origin by lifting it against the seat. That is, the taper surface of the valve element serves as a reference surface for locating the origin of the valve element (for details, refer to Patent Document 1, etc.). 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. The flow rate characteristics (for example, the inflection point of the flow rate at the intermediate opening) may vary.

The present invention has been made in view of the above problems, and an object thereof is to suppress a change in flow rate due to a change in the flow direction of a fluid (refrigerant) when the valve body is at the lowest position. It is to provide an electric valve that can be operated.

Another object of the present invention is to provide an electrically operated valve capable of suppressing variations in the size of the gap formed between the valve body and the valve seat portion at the origin position, and consequently variations in the flow rate characteristics. Especially.

In order to solve the problems described above, the motor-operated valve according to the present invention is provided with a valve shaft provided with a valve body and a valve orifice having a valve seat portion in which the valve body is brought into contact with or separated from or close to each other, A valve main body in which a valve chamber through which a fluid is introduced and drawn 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 main body side. A movable screw portion provided on the valve shaft side, and a screw feed mechanism for moving up and down the valve body of the valve shaft with respect to the valve seat portion of the valve body in accordance with rotational driving of the rotor. A lower stopper mechanism for restricting the downward movement of the valve shaft, wherein the lower stopper mechanism causes the fluid to flow from the valve chamber to the valve orifice when the valve body is at the lowest position. The valve shaft is arranged so as to flow in both directions of a positive direction and a reverse direction from the valve orifice to the valve chamber, and the valve shaft is disposed so as to penetrate the fixing screw portion and is provided at a lower end portion thereof. The valve body is integrally formed, and the valve body has a smaller diameter than a portion of the valve shaft that penetrates through the fixing screw portion, and the valve body has a constant outer diameter in a vertical direction. The valve body side straight part is provided, and the valve seat side part is provided with a valve seat side straight part having a constant inner diameter in the vertical direction, and the valve body side straight part is movable with the fixing screw part in the screw feed mechanism. When the valve shaft is at a lowermost position by the lower stopper mechanism, the length is equal to or more than the length of the backlash between the thread portion and the length at which the valve shaft can be moved by the screw feeding mechanism, It is characterized in that at least a part of the valve body side straight portion and at least a part of the valve seat side straight portion are overlapped in the vertical direction.

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

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

According to the present invention, when the valve body is at the lowest position, at least a part of the valve body side straight portion provided on the valve body and at least a part of the valve seat side straight portion provided on the valve seat portion are provided. The dimensions and shapes of the respective parts are set so that they overlap in the vertical direction. More specifically, when the valve body is farthest from the valve seat when the valve body is at the lowest position (when the fluid flows in the opposite direction), at least a part of the valve body side straight portion and the valve seat side. At least a part of the straight portion overlaps in the vertical direction. Therefore, when the valve body is at the lowest position, even if the valve body moves up and down with respect to the valve seat portion according to the change in the flow direction of the fluid, the flow rate of the fluid flowing through the valve orifice (0 pulse flow rate). ) Is continuously changed, and the valve body that controls the flow rate of the fluid (refrigerant) flowing through the valve orifice is composed of a tapered surface, compared with the conventional motor-operated valve in which the valve body is at the lowest position. It is possible to reliably suppress the change in the flow rate due to the change in the flow direction of the fluid (refrigerant).

Further, a valve body side contact portion having a surface perpendicular to the ascending/descending direction is provided above the valve body side straight portion of the valve body. When the valve body is lowered from the lowered position, the contact portion of the valve body is brought into contact with the valve body. That is, the contact portion (a surface perpendicular to the vertical direction) provided on the valve body side straight portion of the valve body serves as a reference plane for origin determination of the valve body, and the valve body and the valve seat portion at the origin position. The dimensional accuracy of the gap between and depends basically on the part accuracy (machining accuracy) of the abutting portion of the valve element. Therefore, for example, as compared with a conventional motor-operated valve in which the tapered surface of the valve element serves as a reference surface for positioning the origin of the valve element, the dimensional variation of the gap, and thus the flow rate characteristic (e.g., change in flow rate at an intermediate opening). It is possible to effectively suppress the variation of the bending point). Further, since the above-mentioned valve body side straight portion (the length in the up-and-down direction) is determined with reference to the contact portion (reference surface), the dimensional accuracy of the valve body side straight portion can be secured, and from this point as well, the flow rate can be improved. It is possible to more effectively suppress variations in characteristics (eg, inflection point of flow rate at intermediate opening).

The longitudinal section showing one embodiment of the motor-operated valve concerning the present invention. It is a principal part expansion longitudinal cross-sectional view which expands and shows the principal part of the motor operated valve shown by FIG. 1, (A) is a figure which shows a forward direction flow state, (B) is a figure which shows a reverse direction flow state. The figure which shows an example of the flow volume characteristic of the motor operated valve shown by FIG. The figure which shows the other example of the flow volume characteristic of the electrically operated valve shown by FIG. The principal part expanded longitudinal cross-sectional view which expands and shows the principal part of the other example of the electrically operated valve shown by FIG. A top view and a partially enlarged vertical cross section provided for explaining a step of rotating a lower stopper with respect to a guide bush in a step of setting an origin position (lowermost position) of a valve element in a step of assembling a motor-operated valve shown in FIG. 1. Fig. It is a principal part expansion longitudinal cross-sectional view which expands and shows the principal part of the conventional motor operated valve, (A) is a figure which shows a forward direction flow state, (B) is a figure which shows a reverse direction flow state. The figure which shows the flow volume characteristic of the conventional motor operated valve.

Hereinafter, embodiments of a motor-operated valve and an assembling method thereof according to the present invention will be described with reference to the drawings. In addition, in each drawing, a gap formed between members, a separation distance between members, and the like may be exaggerated for easy understanding of the invention and for convenience of drawing. is there. Further, in the present specification, the description indicating the position and direction such as up and down, left and right is based on the direction arrow display in FIG. 1, and does not indicate the position and direction in the actual use state.

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

<Structure and operation of electric valve>
FIG. 1 is a vertical cross-sectional view showing an embodiment of an electric valve according to the present invention.

The electrically operated valve 1 of 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, The compression coil spring (biasing member) 60, the retaining locking member 70, the screw feed mechanism 28, and the lower stopper mechanism 29 are provided.

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 fluid (refrigerant) flowing through the valve orifice 46 at the lower end portion of the lower small-diameter portion 13. The valve body 14 for controlling the passage flow rate of 1) is integrally formed.

As can be seen from FIG. 1 and FIG. 2 as well, the valve body 14 has a cylindrical surface slightly smaller than the lower small-diameter portion 13 of the valve shaft 10 from the upper side (valve chamber 40a side) A straight part (valve side straight part) 14s consisting of a constant), an upper tapered surface part 14t consisting of an inverted truncated cone surface, and a control angle from the upper tapered surface part 14t (intersection angle between a line parallel to the central axis O of the valve body 14) Has a lower taper surface portion 14u formed of an inverted circular truncated cone surface.

The length of the straight portion 14s in the ascending/descending direction (vertical direction) is designed to be equal to or more 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). (See below for details).

Further, on the upper side of 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 valve body 14 (the straight portion 14s thereof). An annular flat surface (horizontal surface) (valve body side contact portion) 14f formed of a surface is provided. The annular flat surface 14f is a surface perpendicular to the ascending/descending direction, and when the valve body 14 is out of the lowest position when the valve body 14 is at the origin position (the lowest position) when the motor-operated valve 1 is assembled. When lowered, it serves as 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 that is inserted such that (the intermediate large diameter portion 12 of) the valve shaft 10 is relatively movable (sliding) in the direction of the axis O and is 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 side of the intermediate large diameter portion 12 and the lower end side of the upper small diameter portion 11 of the valve shaft 10 are inserted into the extension. And the installation portion 22. On the outer periphery of the cylindrical portion 21 of the guide bush 20, one of the screw feeding mechanisms 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. A component fixing screw portion (male screw portion) 23 is formed. Further, 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 into the fitting hole 44 of the valve body 40. A lower stopper 25 is fixed to (on the lower side of the valve shaft holder 30 in) the fixing screw portion 23 by being screwed and fixed to the upper surface 27a of the fitting portion 27 with a predetermined gap h therebetween. A fixed stopper body 24, which constitutes one of the lower stopper mechanisms 29 for restricting the downward movement of the rotation of the valve shaft holder 30 (that is, the valve shaft 10 connected to the valve shaft holder 30), integrally projects on the outer periphery of 25. It is set up. 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 having an insertion hole 32a through which an upper end portion of (the upper small diameter portion 11 of) the valve shaft 10 is inserted. Have A movable screw portion (female screw portion) 33 that is screwed with the fixing screw portion 23 of the guide bush 20 to form the screw feeding mechanism 28 is formed on the inner circumference of the cylindrical portion 31 of the valve shaft holder 30. A movable stopper body 34, which constitutes the other side 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 intermediate 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 portion of the valve shaft 10 is provided. The valve shaft 10 and the valve shaft holder 30 are urged so as to be extrapolated to the portion 11 in the ascending/descending direction (axis O direction), in other words, the valve shaft 10 (valve body 14) is always moved downward. A compression coil spring (biasing member) 60 that biases the valve in the (valve closing direction) is compressed.

The valve body 40 is composed of a metal cylindrical body such as brass or SUS. The valve body 40 has a valve chamber 40a into which a fluid is introduced and led out, and a first conduit 41a is connected and fixed by brazing or the like to a lateral first opening 41 provided at a side portion of the valve chamber 40a. An insertion hole through which the valve shaft 10 (the intermediate large-diameter portion 12 thereof) is relatively movable (sliding) in the direction of the axis O and is relatively rotatable around the axis O in the ceiling of the valve chamber 40a. 43 and a lower portion (fitting portion 27) of the guide bush 20 are fitted to each other to form a fitting hole 44, and a vertical second opening 42 provided at a lower portion of the valve chamber 40a is provided with a fitting hole 44. The two conduits 42a are connected and fixed by brazing or the like. In addition, a substantially frustoconical valve opening orifice 46 having a valve seat portion 46a for contacting or separating the valve body 14 with or away from the bottom wall 45 provided between the valve chamber 40a and the second opening 42. 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 straight portion 46s (inside diameter thereof) is designed to have a diameter 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.

Further, around the valve orifice 46 (valve seat portion 46a) on the upper surface of the bottom wall 45 of the valve body 40, there is an annular flat surface (horizontal plane) (valve body side contact portion) 45f, and the annular flat surface 45f. Is a contact surface (reference surface) that is brought into flat contact with the annular flat surface 14f on the valve body 14 side when the origin position (lowermost position) of the valve body 14 during assembly of the motor-operated valve 1 is set ( 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 a lower end of a cylindrical can 55 with a ceiling is attached to a step provided on the outer periphery of the flange-shaped plate 47. Sealed and joined by butt welding.

A rotor 51 is rotatably arranged inside the can 55 and outside the guide bush 20 and the valve shaft holder 30, and a yoke 52a is provided outside the can 55 to rotate the rotor 51. A stator 52 including a bobbin 52b, a stator coil 52c, and a resin mold cover 52d 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 existing rotor 51 is adapted to rotate around the axis O.

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

Specifically, the rotor 51 has a double pipe structure including an inner cylinder 51a, an outer cylinder 51b, and a connecting portion 51c that connects the inner cylinder 51a and the outer cylinder 51b at a predetermined angular position around the axis O, Vertical grooves 51d extending in the direction of the axis O (vertical direction) (for example, at an angular interval of 120 degrees around the axis O) are formed on the inner circumference of the inner cylinder 51a.

On the other hand, on the outer periphery (upper half portion) of the valve shaft holder 30, there are provided protrusions 30a extending in the vertical direction (for example, at an angular interval of 120 degrees around the axis O), and the lower portion of the protrusions 30a. Upward locking surfaces (not shown) that support the rotor 51 are formed on both sides.

By engaging the vertical groove 51d of the inner cylinder 51a of the rotor 51 with the protrusion 30a of the valve shaft holder 30 and contacting the lower surface of the inner cylinder 51a of the rotor 51 with the locking surface of the valve shaft holder 30, The rotor 51 is supported and fixed in a state of being 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 of the valve shaft holder 30 and the rotor 51 in the up-down direction is prevented (in other words, the rotor 51 is pressed downward against the valve shaft holder 30) and the valve In order to connect the shaft 10 and the valve shaft holder 30, a push nut 71 externally fitted and 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, the push nut 71 and the rotor 51. And a retainer locking member 70 including a rotor retainer 72 made of a disc-shaped member having a through hole 72a formed at the center, which is interposed between the rotor retainer 72 and the upper end portion of the valve shaft 10. ing. That is, the rotor 51 is sandwiched between the valve shaft holder 30 and the rotor retainer 72, which are biased upward by the biasing force of the compression coil spring 60. The height from the upper end of the valve shaft holder 30 to the locking surface (in the vertical direction) is the same as the height of the inner cylinder 51a of the rotor 51 (in the vertical direction), and (the ceiling 32 of the valve shaft holder 30). The upper surface of () 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 moves the valve shaft holder 30 upwards with respect to the guide bush 20 excessively during operation, so that the fixing screw portion 23 of the guide bush 20 and the valve are not moved. In order to prevent the shaft holder 30 from being unscrewed from the movable screw portion 33, a return spring 75, which is 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 set to the lowest position (origin position) in order to prevent the valve body 14 from biting the valve seat portion 46a and ensure controllability in a low flow rate range. At a certain time, a gap having a predetermined size is formed between the valve body 14 and the valve seat portion 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 between the annular flat surface 14f connected to the straight portion 14s and the annular flat surface 45f connected to the straight portion 46s. A gap having a predetermined size is formed between the and.

In the motor-operated valve 1 having such a configuration, when the rotor 51 is rotated by energization of (the stator coil 52c of) the stator 52, the valve shaft holder 30 and the valve shaft 10 are rotated integrally with the rotor 51. At this time, the valve shaft 10 is moved up and down 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. The gap (lift amount, valve opening) between the valve seat 46a and the valve seat portion 46a is increased or decreased to adjust the flow rate of the fluid such as the 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 come into contact with each other, and the valve body 14 is at the lowest position, the valve body 14 and the valve seat are not in contact with each other. Since a gap (a required lift amount at the time of closing the valve) is formed between the portion 46a and the portion 46a, a predetermined amount of passing flow rate is secured (see FIG. 3).

By the way, in the motor-operated valve 1 of the present embodiment, the fluid (refrigerant) is bidirectional, specifically, from the first conduit 41a (first opening 41) to the second conduit via the valve chamber 40a and the valve orifice 46. 42a (the second opening 42) in the direction (that is, the lateral → downward direction) (hereinafter, this state is referred to as a forward flow state), and from the second conduit 42a (the second opening 42) to the valve orifice 46 and the valve chamber. 40a through the first conduit 41a (first opening 41) in the direction (that is, downward → lateral direction) (hereinafter, this state is referred to as a reverse flow state), and is designed to flow in both directions. 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. Then, in the screw feed mechanism 28 that raises and lowers the valve body 14 with respect to the valve seat portion 46a, the movable screw portion 33 of the valve shaft holder 30 to which the valve body 14 (valve shaft 10) is coupled and the valve body 40 are fixedly coupled. There is backlash (screw play) between the guide bush 20 and the fixed 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 fixing screw portion 23 of the guide bush 20) ( 2(A), in the reverse flow state, the valve body 14 (the upper surface side of the movable screw portion 33 of the valve shaft holder 30 and the lower surface side of the fixing screw portion 23 of the guide bush 20 are in contact with each other. Until it is moved) (the state shown in FIG. 2(B)). 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 body 14 moves up and down with respect to the valve seat portion 46a by the backlash amount.

Here, in the present embodiment, when the valve body 14 is at the lowest position, at least a portion of the straight portion 14s on the valve body 14 side and at least a portion of the straight portion 46s on the valve seat portion 46a side move in the vertical direction. The dimensions and shapes of the respective parts are set so as to overlap (wrap) in the (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 (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 made to overlap by an overlapping amount (lap amount) Lmin in the ascending/descending direction (state shown in FIG. 2B).

Further, 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 side in the vertical direction is equal to the overlapping amount Lmin of the screw feed mechanism 28. The amount is the amount of backlash added (the state shown in FIG. 2(A)).

Therefore, as shown in FIG. 3, when the valve body 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 body 14 moves toward the valve seat. Even if it moves up and down with respect to the portion 46a, the passage flow rate (0 pulse flow rate) of the fluid flowing through the valve orifice 46 is continuously changed. For example, the passage flow rate of the fluid (refrigerant) flowing through the valve orifice is changed. Compared with the conventional motor-operated valve in which the valve body to be controlled has a tapered surface, it is possible to reliably suppress the change in the flow rate due to the change in the flow direction of the fluid (refrigerant) when the valve body 14 is at the lowest position. it can.

Further, in the present embodiment, an annular flat surface (valve body side contact portion) 14f having a surface perpendicular to the vertical 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 (valve main body side contact portion) 45f is provided around the valve orifice 46 (valve seat portion 46a) on the upper surface of the valve 45, and when the valve body 14 is set to the origin position (lowermost position) at the time of assembly. When the valve body 14 is lowered from the lowest position, the annular flat surface 14f on the valve body 14 side is brought into contact with the annular flat surface 45f on the valve body 40 side. That is, the annular flat surface 14f provided on the upper side of the straight portion 14s of the valve body 14 and the annular flat surface 45f of the valve body 40 serve as a reference plane for the origin position of the valve body 14, and the valve body 14 and the valve at the origin position. The dimensional accuracy of the gap with the seat portion 46a basically depends on the part accuracy (processing accuracy) of the annular flat surface 14f of the valve body 14 (detailed later). Therefore, for example, as compared with a conventional motor-operated valve in which the tapered surface of the valve element serves as a reference surface for positioning the origin of the valve element, the dimensional variation of the gap, and thus the flow rate characteristic (e.g., change in flow rate at an intermediate opening). It is possible to effectively suppress the variation of the bending point). Further, since the length of the straight portion 14s on the valve body 14 side in the vertical direction is determined with reference to the annular flat surface 14f (reference surface), the dimensional accuracy of the straight portion 14s on the valve body 14 side can be secured. From this point as well, it is possible to more effectively suppress the variation in the flow rate characteristics (for example, the inflection point of the flow rate at the intermediate opening degree).

In the example shown in FIG. 3, in the reverse flow state in which the valve element 14 is biased upward, the lower portion of the straight portion 14s on the valve element 14 side and the upper portion of the straight portion 46s on the valve seat portion 46a side. The portion overlaps with the predetermined overlap amount Lmin in the ascending/descending direction. For example, as shown in FIG. 4, in the reverse flow state, the lower end of the straight portion 14s on the valve body 14 side and the valve The size and shape of each portion may be set so that the upper end portion of the straight portion 46s on the side of the seat portion 46a matches (that is, the overlapping amount Lmin in the vertical direction is 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 side in the vertical direction is the backlash of the screw feed mechanism 28.

Further, in the above-described embodiment, the annular flat surface 14f on the valve body 14 side and the annular flat surface 45f on the valve body 40 side are in contact with each other at the surface, but may be in contact with other than the surface, for example, the valve body. 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 protruding shape in 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 in the bottom wall 45 of the valve body 40, but, for example, as shown in FIG. A seat member 48 in which the valve orifice 46 having the valve seat portion 46a provided with the straight portion 46s is formed is produced by cutting or the like, and the seat member 48 is fitted and inserted in the bottom wall 45 of the valve body 40. It may be inserted and fixed in the hole 49. In this case, an area around the valve orifice 46 (valve seat portion 46a) on the upper surface of the seat member 48 is an annular flat surface (horizontal surface) (valve body side contact portion) 48f, and the valve body when the electric valve 1 is assembled It is a contact surface (reference surface) that is brought into flat contact with the annular flat surface 14f on the side of the valve body 14 when the origin position (lowermost position) of 14 is reached.

As shown in FIG. 5, by using the seat member 48 that 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. Therefore, the variation in the flow rate characteristics can be suppressed more effectively.

<How to assemble the motorized valve>
An example of an assembling process of the electrically operated valve 1 described above, particularly an example of an origin position (lowermost position) setting process of the valve element 14, will be outlined with reference to FIGS. 1 and 2. First, the valve shaft 10 and the guide bushing will be described. 20, the lower stopper 25, the compression coil spring 60, the valve shaft holder 30, the rotor 51, the valve body 40, etc. are assembled. At this time, the lower stopper 25 is screwed onto the guide bush 20 so as to be rotatable relative thereto. The lower stopper 25 may be disposed in contact with the stopper portion 27a of the guide bush 20 at this stage, or may be disposed apart from the stopper portion 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, the movable stopper body 34 of the valve shaft holder 30 and the fixed stopper body 24 of the lower stopper 25 contact each other, and the lower stopper 25 (the lower surface thereof) contacts the stopper portion 27a of the guide bush 20. Using the screw feed mechanism 28 including the fixing screw portion 23 of the guide bush 20 and the movable screw portion 33 of the valve shaft holder 30, the valve shaft holder 30, the rotor 51, and the valve shaft 10 are rotated and lowered. Let In this way, the valve shaft holder 30 is positioned at the lowermost moving position, and the valve body 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 fitted and fixed by press fitting, welding or the like.

Next, from the above-mentioned state, the 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 is attached to the screw feed mechanism 28. After being used to rotate and raise to remove from the guide bush 20, the lower stopper 25 is rotated with respect to the guide bush 20 in the valve opening direction (counterclockwise in plan view) by a predetermined rotation angle. Then, the lower stopper 25 is connected and fixed to (the fixing screw portion 23 of) the guide bush 20 by welding, welding, bonding or the like so as not to be relatively rotatable, and then the screw feed mechanism 28 is used again to reassemble the assembly into the guide bush. Assemble to 20. As a result, the position of the fixed stopper body 24 of the lower stopper 25 with respect to the guide bush 20 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 come into contact with each other, and the valve shaft holder 30 is Even in the lowermost position (that is, when the valve element 14 is in the lowest position), a gap of a predetermined size between the valve element 14 and the valve seat portion 46a (ascending/descending direction in the forward flow state) A space having a dimension of H) is formed (see FIG. 2A). At this time, 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 side in the up-and-down direction is, for example, the amount of 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 with respect to the guide bush 20 by a predetermined rotation angle in the valve opening direction, and the lower stopper 25 is welded and welded to the guide bush 20. The description has been made assuming that they are connected and fixed so as not to rotate relative to each other by adhesion or the like, but only by raising the assembly with respect to the guide bush 20, the lower stopper 25 with respect to the guide bush 20 is rotated by a predetermined rotation angle in the valve opening direction. As long as the gap can be rotated and the lower stopper 25 can be connected and fixed to the guide bush 20 in a non-rotatable manner by welding, welding, bonding, etc., the assembly can be removed from the guide bush 20. No need to remove.

When a backlashless (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 The dimension H of the gap formed therebetween in the up-and-down direction matches or substantially matches the gap h between (the lower surface of) the lower stopper 25 and the stopper portion 27a of the guide bush 20. However, in general, the screw portion is provided with backlash (play or play). 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 (loosened) in the valve opening direction to perform the origin position determination of the valve body 14, In 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 necessarily match the gap h.

Specifically, as will 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 θb[°] (Fig. In the example shown, about 180°), the lower stopper 25 is brought into contact with the stopper portion 27a of the guide bush 20 and tightened in the above-described origin position locating step (in this state, the female screw portion of the lower stopper 25). When the lower stopper 25 is rotated (loosened) in the valve opening direction from the contact between the upper surface side of 26 and the lower surface side of the fixing screw portion 23 of the guide bush 20, within the range of the rotation angle θb [°] for the backlash. Then, the lower stopper 25 (lower surface of the lower stopper) keeps contacting with the stopper portion 27a of the guide bush 20 by 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.

Temporarily, 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 screw shaft feed mechanism 28 is used to lower the valve shaft holder 30 while rotating the valve shaft holder 30. 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 moving position of the valve shaft holder 30 gradually rises according to the rotation amount of the lower stopper 25. For example, the amount of rise Hb of the valve shaft holder 30 at the most lowered position at the time of backlash offset is p×θb/360, where p is the thread pitch of the female thread portion 26 of the lower stopper 25. It is defined ((3) in FIG. 6).

After the backlash is offset (after the rotation angle of the lower stopper 25 reaches the rotation angle θb[°] for the backlash) (in this state, the lower surface of the female screw portion 26 of the lower stopper 25 and the fixing screw of the guide bush 20 are fixed). 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, assuming that the lower stopper 25 is brought into contact with the stopper portion 27a of the guide bush 20 and tightened, the lower stopper 25 is rotated in the valve opening direction by the rotation angle θ [°] to be fixed to the guide bush 20. When the valve shaft holder 30 is at the lowermost moving position (that is, when the valve body 14 is at the lowest position), the lowest position of the holder 30 is increased by the amount of increase H defined by p×θ/360. ), a gap having a predetermined dimension H in the ascending/descending direction (in the forward flow state) is formed between the valve body 14 and the valve seat portion 46a (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 amount from the amount of rise 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 portion 27a of the guide bush 20 by rotating the lower stopper 25 beyond the rotation angle θb[°] corresponding to the backlash. However, when the dimension in the up-and-down direction of the gap formed between the valve body 14 and the valve seat portion 46a is set to Hb or less, the lower stopper 25 is within the range of the backlash rotation angle θb[°]. Since there is no need to make a gap between the lower stopper 25 and the stopper portion 27a of the guide bush 20, the lower stopper 25 (the lower surface thereof) remains in contact with the stopper portion 27a of the guide bush 20. ..

Further, 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 of the rotation of the lower stopper 25 in the valve opening direction. It is needless to say that the fastening state and the vertical position of the lower stopper 25 are not limited to those in the illustrated embodiment. For example, the lower stopper 25 may use any state within the range of the rotation angle for the backlash shown in (1) to (3) of FIG. 6 as the reference state. Further, the lower stopper 25 does not need to be in contact with the stopper portion 27a of the guide bush 20 in the reference state, and for example (the fixing screw portion 23 of the guide bush 20) as shown in (4) of FIG. Any position in can be used as the reference state. When the lower stopper 25 is separated from (not in contact with) the stopper portion 27a of the guide bush 20 as the reference state, the backlash does not exist, and the valve body 14 and the valve are not separated after the assembly is completed. The dimension H of the gap formed between the seat portion 46a and the seat portion 46a in the vertical direction 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 portion 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 and exciting the stator 52 (the stator coil 52c of the stator 52), the valve shaft holder 30 and the valve shaft 10 are integrated with the rotor 51. It can be rotated. At this time, the valve shaft 10 is moved up and down 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. The gap (lift amount, valve opening) between the valve seat 46a and the valve seat portion 46a is increased or decreased to adjust the flow rate of the fluid such as the 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 come into contact with each other, and the valve body 14 is at the lowest position, the valve body 14 and the valve seat are not in contact with each other. Since a gap (a required lift amount at the time of closing the valve) is formed between the portion 46a and the portion 46a, a predetermined amount of passing flow rate is secured (see FIG. 3).

In the motor-operated valve 1 of the present embodiment, the lower stopper 25 having the female threaded portion 26 of the thread 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 annular flat surface 14f of the valve body 14 is brought into contact with the annular flat surface 45f of the valve body 40 by moving the valve body 14 from the lowermost position while being positioned at the moving position, and then the annular flat surface of the valve body 14 is moved. With reference to the position where 14f abuts on the annular flat surface 45f of the valve body 40, the lower stopper 25 at the predetermined position is rotated with respect to the guide bush 20 by a predetermined rotation angle θ in the valve opening direction, and the guide bush 25 is rotated. When the valve shaft holder 30 is in the lowermost moving position by the lower stopper mechanism 29, the space between the valve body 14 and the valve seat portion 46a (specifically, the annular flat surface 14f and the annular flat surface 14f). (A space between the flat surface 45f) and a dimension H in the ascending/descending direction in the forward direction is defined by p×θ/360, and at least a part of the straight portion 14s of the valve body 14 and the valve At least a part of the straight portion 46s of the seat portion 46a overlaps in the vertical direction. That is, since the lower stopper 25 is rotated in the valve opening direction with respect to the guide bush 20 and is connected to the guide bush 20 in a relatively non-rotatable manner, the lowermost position of the valve body 14 in the forward flow state, in other words, For example, the gap in the up-and-down 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 body 14 and the valve seat portion 46a at the origin position is basically determined by 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, it is possible to suppress the dimensional variation of the gap, thereby improving the controllability of the flow rate of the fluid (refrigerant) in the low flow rate range. Furthermore, the annular flat surface 14f provided on the upper side of 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 origin position determination at the time of assembly of the valve body 14, so that at the origin position. The dimensional accuracy of the gap between the valve body 14 and the valve seat portion 46a basically depends on the component accuracy (machining accuracy) of the annular flat surface 14f of the valve body 14, resulting in dimensional variation of the gap, and by extension, It is possible to effectively suppress the variation in the flow rate characteristic (for example, the inflection point of the flow rate at the intermediate opening).

1 Motorized valve 10 Valve shaft 14 Valve body 14f Annular flat surface (valve side contact part)
14s Straight part on valve body 20 Guide bush 21 Cylindrical part 23 Fixing screw part (male screw part)
28 Screw feeding mechanism 29 Lower stopper mechanism 30 Valve shaft holder 33 Movable screw part (female screw part)
40 valve main body 40a valve chamber 41 first opening 41a first conduit 42 second opening 42a second conduit 45 bottom wall 45f annular flat surface (main body side contact portion)
46 valve orifice 46a valve seat part 46s valve seat side straight part 47 collar part 48 seat member 50 stepping motor 51 rotor 52 stator 55 can 60 compression coil spring 70 retaining lock member O axis

Claims (3)

A valve shaft provided with a valve body, a valve body having a valve opening having a valve seat portion for moving the valve body into contact with or away from the valve body, and a valve body having a valve chamber into which a fluid is introduced and discharged; A rotor having a rotor connected to the 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 moving the valve body of the valve shaft up and down with respect to the valve seat portion of the valve body according to the rotational drive of the valve shaft, and a lower stopper mechanism for restricting the downward movement of the valve shaft. ,,
When the valve body is at the lowest position by the lower stopper mechanism, the fluid flows in both the forward direction from the valve chamber to the valve orifice and the reverse direction from the valve orifice to the valve chamber. A motorized valve designed to
The valve shaft is disposed so as to penetrate the fixing screw portion, and the valve body is integrally formed at a lower end portion thereof,
The valve body has a smaller diameter than a portion penetrating the fixing screw portion of the valve shaft,
The valve body is provided with a valve body side straight portion having a constant outer diameter in the vertical direction, and the valve seat portion is provided with a valve seat side straight portion having a constant inner diameter in the vertical direction,
The valve body side straight portion is not less than the length of the backlash between the fixed screw portion and the movable screw portion in the screw feed mechanism, and is less than or equal to the length by which the valve shaft can be moved by the screw feed mechanism,
When the valve body is at the lowest position by the lower stopper mechanism, at least a part of the valve body side straight portion and at least a part of the valve seat side straight portion are arranged to overlap each other in the vertical direction. Characteristic motorized valve. The electric valve according to claim 1, wherein the valve seat portion and the valve orifice are formed in a part of the valve body. The motor-operated valve according to claim 1, wherein the valve seat portion and the valve orifice are formed in a seat member that is internally fixed in a fitting hole formed in a part of the valve body. ..

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