JP7175035B2 - flow control valve - Google Patents

Description

The present invention relates to flow control valves.

A motor-driven valve used as a flow control valve in a refrigeration cycle has a screw mechanism in which a male threaded portion of a valve shaft rotated by a motor is screwed into a female threaded hole provided in a valve body, The screw mechanism converts rotary motion into axial motion, thereby displacing the valve stem in the axial direction and controlling the flow rate.

For example, in a flow control valve as disclosed in Patent Document 1, a valve body defining a valve chamber therein is joined to a bottomed cylindrical can that accommodates a rotor of a motor and a screw mechanism. In such a flow control valve, the male threaded portion of the rotor shaft connected to the rotor rotates with respect to the female threaded hole, thereby axially moving the rotor shaft and axially moving the valve holder holding the needle valve. can be done. In addition, the sealed valve body and can are filled with refrigerant.

JP 2018-119595 A

By the way, the refrigerant circulating in the refrigerating cycle may be contaminated with foreign matter during operation of the compressor or the like. Therefore, it is expected that the refrigerant mixed with foreign matter may enter the valve body and the can of the flow control valve through the pipe and reach the vicinity of the screw mechanism. In such a case, in the flow control valve of Patent Document 1, since the end of the male threaded portion is exposed to the outside from the female threaded hole, foreign matter adhering to the male threaded portion may enter the female threaded hole as the rotor shaft moves in the axial direction. The foreign matter may enter the screw mechanism, causing jamming or the like between the screws, thereby hindering the smooth operation of the screw mechanism.

On the other hand, it is also an idea to arrange a fine-mesh filter or the like at the inlet of the refrigerant of the flow control valve to catch the foreign matter mixed in the refrigerant. However, if a filter or the like is installed in the flow control valve, the cost of the flow control valve will increase, and the filter will need to be cleaned regularly, increasing the maintenance effort.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a flow control valve capable of ensuring smooth operation while suppressing costs and labor for maintenance.

In order to solve the above problems, the flow control valve of the present invention is
Can and
a valve body joined to the can;
Having a valve shaft arranged in a space surrounded by the can and the valve body and rotatable with respect to the valve body, and a guide stem fixed with respect to the valve body,
The valve stem is composed of an integral member and has a male threaded portion, an upper cylindrical portion arranged above the male threaded portion, and a lower cylindrical portion arranged below the male threaded portion ,
The guide stem includes a female threaded hole that is screwed into the male threaded portion, an upper end guide portion that is arranged above the female threaded hole and faces the upper cylindrical portion, and a lower cylindrical portion that is arranged below the female threaded hole. has a lower end guide portion facing the
Both the radial clearance between the upper end guide portion and the upper cylindrical portion and the radial clearance between the lower end guide portion and the lower cylindrical portion are larger than the radial clearance between the female threaded hole and the male threaded portion. Characterized by being small.

ADVANTAGE OF THE INVENTION According to this invention, the flow control valve which can ensure smooth operation|movement can be provided, suppressing the effort of cost and maintenance.

FIG. 1 is a longitudinal sectional view showing a flow control valve according to an embodiment of the invention. FIG. 2 is a cross-sectional view showing an enlarged part of the female threaded hole and the male threaded portion of the flow control valve. FIG. 3 is a vertical cross-sectional view showing a flow control valve according to a comparative example.

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

FIG. 1 is a longitudinal sectional view showing a flow control valve 1 according to an embodiment of the invention. Here, the rotor side of the flow control valve 1 is referred to as the upper side, and the needle valve side is referred to as the lower side.

(Configuration of flow control valve)
The flow control valve 1 includes a bottomed cylindrical valve body 10 whose upper end is open, a capped cylindrical can 45 whose lower end is hermetically joined to the upper end surface of the valve body 10 by welding or the like, and the valve body 10. A guide stem 15 fixed inside, a valve shaft 21 arranged inside the guide stem 15, a rotor 30 integrally rotatably connected and fixed to the valve shaft 21, and the rotor 30 is driven to rotate. A stator 50 fitted on the outer circumference of the can 45 is provided. Here, the rotor 30 and the stator 50 constitute a stepping motor. Let L be the axis of the flow control valve 1 .

The valve body 10 is formed by connecting a hollow cylindrical portion 10a and a bottom wall portion 10b. The valve body 10 can be formed by press-molding a plate material made of SUS, but may be formed by forging a SUS material.

A circular opening 10d is formed in the center of the bottom wall portion 10b, and a valve seat member 11 is fixed to the opening 10d by brazing or the like. The valve seat member 11 comprises a small-diameter cylindrical portion 11a fitted in the opening 10d and a large-diameter cylindrical portion 11b having a larger diameter than the small-diameter cylindrical portion 11a. The end of the first pipe T1 is inserted into the inner periphery of the large-diameter cylindrical portion 11b and connected by brazing or the like.

The valve seat member 11 has an orifice 11d passing through its center, and a valve seat 11e is formed at the upper end of the orifice 11d. The orifice 11d expands in diameter toward the lower end side.

An inlet opening 10e is formed in the hollow cylindrical portion 10a of the valve body 10, and the end of the second pipe T2 is inserted into the inlet opening 10e and connected by brazing or the like. Let O be the axis of the entrance opening 10e.

With the lower end of the can 45 abutting against the upper end of the valve body 10, the collar-shaped disk 18 is fitted to the inner circumference of the lower end of the can 45, and these are joined by welding. As a result, the valve body 10 and the can 45 are integrated in a hermetically sealed state.

The brim-shaped disc 18 has a plurality of through holes 18a through which the refrigerant can move between the valve main body 10 side and the can 45 side.

In FIG. 1, a stator 50 including a yoke 51, a bobbin 52, a stator coil 53, and a resin mold cover (not shown) is arranged outside the can 45. As shown in FIG. The stator coil 53 is connected to an external control device via a lead wire (not shown), and the rotor 30 arranged in the can 45 can be rotated around the axis L by energization and excitation of the stator coil 53 . .

The resin-made guide stem 15 disposed inside the rotor 30 comprises a solid cylindrical main body 15a and a hollow cylindrical portion 15b. The main body 15a has a through opening 15e passing through its center. The through opening 15e includes a cylindrical upper end guide portion 15f on the upper end side, a cylindrical lower end guide portion 15g on the lower end side, and a female screw hole 15c formed between the upper end guide portion 15f and the lower end guide portion 15g. and Since the inner diameter of the lower end guide portion 15g is larger than the outer diameter of the screw thread of the male thread portion 21b of the valve shaft 21, the valve shaft 21 can be inserted into the guide stem 15 from below. In addition, since the inner diameter of the upper end guide portion 15f is smaller than the outer diameter of the screw thread of the male screw portion 21b, the valve closing direction movable stopper 35 can be installed using the stepped portion.

A collar-shaped disk 18 welded to the upper end of the valve body 10 is fixed to the outer periphery of the intermediate portion of the hollow cylindrical portion 15b. It is A pressure equalizing hole 15d is formed in the hollow cylindrical portion 15b.

In order to set the origin position for control of the rotor 30 and the valve shaft 21, a fixed stopper 55 for the valve closing direction having a rectangular cross section is provided on the upper surface of the main body 15a of the guide stem 15, and protrudes upward. A valve-opening direction fixed stopper 56 having a rectangular cross section projects downward from the lower surface of the main body 15 a of the guide stem 15 . Here, the origin position for control of the rotor 30 and the valve shaft 21 means that the movable stopper 35 for the valve-closing direction is in contact with the fixed stopper 55 for the valve-closing direction, and the rotor 30 and the valve shaft 21 are at the lowest position. is the position when it reaches

The metal valve shaft 21 has an end portion 21a fitted with an annular connecting body 32 attached to the rotor 30, an upper cylindrical portion 21f fitted to the upper end guide portion 15f of the guide stem 15, and an internal screw hole 15c. A male threaded portion 21b to be screwed together, a lower cylindrical portion 21g to be fitted to the lower end guide portion 15g, and a lower end connecting portion 21d are coaxially connected.

Here, the radial gap between the upper end guide portion 15f and the upper cylindrical portion 21f and the radial gap between the lower end guide portion 15g and the lower cylindrical portion 21g are the radial gaps between the female threaded hole 15c and the male threaded portion 21b. is getting smaller.

Here, the radial gap between the upper end guide portion 15f and the upper cylindrical portion 21f refers to the difference between the inner diameter of the upper end guide portion 15f and the outer diameter of the upper cylindrical portion 21f, and the gap between the lower end guide portion 15g and the lower cylindrical portion. 21g refers to the difference between the inner diameter of the lower end guide portion 15g and the outer diameter of the lower cylindrical portion 21g. The radial gap between the female threaded hole 15c and the male threaded portion 21b will be described below.

FIG. 2 is a cross-sectional view showing an enlarged part of the female screw hole 15c and the male screw portion 21b. A predetermined backlash exists in the axial direction between the female threaded hole 15c and the male threaded portion 21b. Due to this backlash, the female threaded hole 15c and the male threaded portion 21b can also move relative to each other in the radial direction.

In FIG. 2, the male threaded portion 21b radially closest to the female threaded hole 15c is indicated by a solid line, and the male threaded portion 21b radially most distant from the female threaded hole 15c is indicated by a dotted line. As is apparent, the proximity or separation between the female threaded hole 15c and the male threaded portion 21b is reversed on the opposite side with the axis L interposed therebetween.

In FIG. 2, the radial distance Δ (ΔMax in FIG. 2) between the female threaded hole 15c and the male threaded portion 21b farthest from the female threaded hole 15c is defined as the radial gap between the female threaded hole 15c and the male threaded portion 21b. defined as A radial gap between the upper end guide portion 15f and the upper cylindrical portion 21f and a radial gap between the lower end guide portion 15g and the lower cylindrical portion 21g are both less than the distance ΔMax.

A space S between the female threaded hole 15c and the male threaded portion 21b having a distance ΔMax extends helically around the male threaded portion 21b to form a gap between the upper end guide portion 15f and the upper cylindrical portion 21f and the lower end It is connected to the gap between the guide portion 15g and the lower cylindrical portion 21g.

In FIG. 1, a valve closing direction movable stopper 35 fixed by press fitting to the end portion 21a of the valve shaft 21 is disposed so as to abut against a step portion between the end portion 21a and the upper cylindrical portion 21f, It is engaged with the lower surface of the upper wall of the rotor 30 . A stopper portion 35a having a rectangular cross section is formed on the lower surface of the movable stopper 35 for the valve closing direction.

A valve-opening direction movable stopper 36 is press-fitted to the lower end of the lower cylindrical portion 21g of the valve shaft 21 so as to abut against the upper surface of the brim portion 21c. A stopper portion 36a having a rectangular cross section is formed on the upper surface of the movable stopper 36 for the valve opening direction. A female thread may be formed on the inner periphery of the valve-opening direction movable stopper 36, and a male thread may be formed on the outer periphery of the lower cylindrical portion 21g.

Below the valve shaft 21 , a valve holder 23 is slidably fitted inside the valve holder 23 . The valve holder 23 has a truncated cylindrical shape in which a hollow cylindrical portion 23a and an upper wall 23b are connected. A stepped opening 23c is formed in the center of the upper wall 23b, and the hollow cylindrical portion 23a has a communicating hole 23d. The open lower end of the hollow cylindrical portion 23a of the valve holder 23 is disposed below the second pipe T2 and closed by an annular member 27 which is crimped and fixed.

The lower end connecting portion 21d passes through the stepped opening 23c in a state where the flange portion 21c of the valve shaft 21 is in contact with the stepped portion of the stepped opening 23c. By processing, the valve shaft 21 and the valve holder 23 are fixedly connected. A valve chamber 29 is defined between the valve body 10 and the valve holder 23 .

A needle valve 25 is arranged such that its tip protrudes from the valve holder 23 through the annular member 27 . The needle valve 25 comprises a valve collar portion 25a, a cylindrical portion 25b, and a conical portion 25c whose diameter decreases downward.

Since the outer diameter of the valve collar portion 25 a is larger than the inner diameter of the annular member 27 , the needle valve 25 is prevented from falling off from the valve holder 23 . A washer 28 is arranged between the valve collar portion 25 a and the annular member 27 .

Between the upper wall 23b of the valve holder 23 and the needle valve 25, a cylindrical spring receiving member 26 having a lower flange 26a is arranged. A coil spring 24 is arranged between the upper wall 23b and the lower flange 26a to urge the spring receiving member 26 downward against the valve holder 23. As shown in FIG.

When the conical portion 25c is seated on the valve seat 11e of the valve seat member 11 and receives an upward pressing force, the spring receiving member 26 urged upward by the needle valve 25 is pushed upward by the upper wall 23b of the valve holder 23. The needle valve 25 is axially locked to the valve shaft 21 by contacting the lower surface (or the lower end connecting portion 21d).

The valve shaft 21, the valve holder 23, the needle valve 25, and the coil spring 24 are substantially integrated with the guide stem 15 when the needle valve 25 is separated from the valve seat 11e (valve open state). ascends and descends while rotating.

(Operation of flow control valve)
The operation of the flow control valve 1 will be specifically described.
Here, it is assumed that refrigerant (fluid) is entering the valve chamber 29 from the second pipe T2.

By supplying pulse power to the stator 50 from an external control device, the rotor 30 and the valve shaft 21 are rotationally driven in one direction, and the valve shaft 21 and the valve are closed by a screw feed mechanism consisting of a female screw hole 15c and a male screw portion 21b. The directional movable stopper 35 descends while rotating, and the needle valve 25 is seated on the valve seat 11e to close the orifice 11d. This blocks the flow of refrigerant from the valve chamber 29 toward the first pipe T1.

At this time, the movable stopper 35 is not yet in contact with the fixed stopper 55, the rotor 30 and the valve shaft 21 do not stop rotating, and pulse power supply continues until the coil spring 24 is compressed by a predetermined amount. As a result, the rotation of the needle valve 25 is restrained while being seated on the valve seat 11e, while the rotor 30, the valve shaft 21, the valve holder 23, and the like further rotate and descend.

At this time, since the valve shaft 21 and the valve holder 23 are lowered with respect to the seated needle valve 25 , the coil spring 24 is contracted and compressed, thereby absorbing the downward force of the valve shaft 21 and the valve holder 23 . After that, when the amount of compression of the coil spring 24 reaches a predetermined amount, the movable stopper 35 abuts against the fixed stopper 55 and is locked. Even if it continues, the descent of the rotor 30 and the valve shaft 21 is forcibly stopped.

In this manner, even after the needle valve 25 is seated on the valve seat 11e and the orifice 11d is closed, the rotor 10 is still maintained until the movable stopper 35 reaches the control origin position where the movable stopper 35 abuts against the fixed stopper 55 and is locked. 30, the valve stem 21, and the valve holder 23 continue to rotate downward, and the coil spring 24 is compressed. Therefore, the needle valve 25 is strongly pressed against the valve seat 11e by the urging force of the coil spring 24, thereby reliably preventing refrigerant leakage and the like.

On the other hand, when a reverse polarity pulse power supply is applied to the stator 50 from the control origin position, the rotor 30 and the valve shaft 21 are driven to rotate in the direction opposite to that when the valve is closed, and the screw formed by the female screw hole 15c and the male screw portion 21b is rotated. The feed mechanism raises the rotor 30, the valve shaft 21, the valve holder 23, and the valve opening direction movable stopper 36 while rotating. As a result, the pressing force applied to the needle valve 25 is weakened, the coil spring 24 expands, and when the needle valve 25 is separated from the valve seat 11e, the orifice 11d is opened. As a result, the refrigerant that has entered the valve chamber 29 from the second pipe T2 passes through the gap between the conical portion 25c and the valve seat 11e, etc., and passes through the orifice 11d to the first pipe T1. flow.

In this case, since the lift amount of the needle valve 25 is determined according to the pulse power supply to the stator 50, the refrigerant flow rate can be controlled. By continuing the pulse power supply, the needle valve 25 is finally fully opened. When the pulse power supply continues, the movable stopper 36 abuts against the valve-opening direction fixed stopper 56 and is locked, thereby forcibly rotating and lifting the rotor 30, the valve shaft 21, and the valve holder 23. be stopped.

Next, the effects of the flow control valve 1 of this embodiment will be described with reference to a valve main body as a comparative example. FIG. 3 is a longitudinal sectional view showing a flow control valve 1A according to a comparative example, but the stator is omitted.
In the comparative example, the shapes of the valve shaft 21A, the guide stem 15A, the valve closing direction movable stopper 35A, and the valve opening direction movable stopper 36A are different from those of the above embodiment. Other common configurations are denoted by the same reference numerals, and overlapping descriptions are omitted.

In FIG. 3, the valve shaft 21A does not have an upper end cylindrical portion and a lower end cylindrical portion on both sides of the male thread portion 21Ab, and the guide stem 15A does not have an upper end guide portion and a lower end guide portion. A female screw hole 15Ac is formed through 15Aa. The male threaded portion 21Ab protrudes from both ends of the female threaded hole 15Ac and is exposed in the space inside the can 45. The valve closing direction movable stopper 35A and the valve opening direction movable stopper 36A are screwed into the exposed male threaded portion 21Ab. is doing.

In the flow control valve 1A, the refrigerant entering the valve chamber 29 from the second pipe T2 flows through the through hole 18a of the brim-shaped disk 18 from the valve main body 10 side to the can 45 side. Part of the refrigerant flows through the pressure equalizing hole 15Ad into the hollow cylindrical portion 15Ab of the guide stem 15A, and the rest of the refrigerant passes between the rotor 30 and the main body 15Aa and reaches the top of the valve shaft 21A. Here, foreign matter such as metal powder mixed in the coolant moves into the can 45 together with the coolant.

In the flow control valve 1A shown in FIG. 3, the male threaded portion 21Ab protrudes so as to be exposed from both ends of the female threaded hole 15Ac. In such a case, foreign matter may be drawn into the female threaded hole 15Ac as the valve stem 21A moves, and may be caught between the male threaded portion 21Ab and the female threaded hole 15Ac. It is feared that smooth relative movement between the valve shaft 21A and the guide stem 15A may be hindered by this foreign matter being caught.

On the other hand, according to the flow control valve 1 of this embodiment shown in FIG. More specifically, an upper cylindrical portion 21f is formed on the upper side of the male thread portion 21b of the valve shaft 21 so as to face the upper end guide portion 15f, and a lower cylindrical portion 21g is formed on the lower side thereof and faces the lower end guide portion 15g. It is formed by Furthermore, the radial gap between the upper end guide portion 15f and the upper cylindrical portion 21f and the radial gap between the lower end guide portion 15g and the lower cylindrical portion 21g are the radial gap ( distance ΔMax).

For this reason, relatively large foreign matter cannot pass through the gap between the upper end guide portion 15f and the upper cylindrical portion 21f or the gap between the lower end guide portion 15g and the lower cylindrical portion 21g. can not enter, foreign matter will not be caught.

On the other hand, relatively small foreign matter passes through the gap between the upper end guide portion 15f and the upper cylindrical portion 21f or the gap between the lower end guide portion 15g and the lower cylindrical portion 21g, and passes between the female threaded hole 15c and the male threaded portion 21b. may enter. However, since such a foreign matter has a dimension smaller than the distance Δ (ΔMax), it remains in the spiral space S shown in FIG. it is less.

Here, the distance Δ and the size of the foreign matter will be further explained. As shown in FIG. 2, the distance Δ varies because the male threaded portion 21b can move radially with respect to the female threaded hole 15c. The distance Δ of the solid line position where the male threaded portion 21b is radially closest to the female threaded hole 15c is ΔMin, the distance Δ of the dotted line position where the male threaded portion 21b is radially most distant from the female threaded hole 15c is ΔMax, Let ΔMid (=(ΔMin+ΔMax)/2) be the intermediate distance between ΔMin and ΔMax. In this case, if the foreign matter is of a size that fits in the space S formed when the gap ΔMid is formed, even if the foreign matter stays in the space S, the male threaded portion 21b can rotate coaxially with the central axis of the female threaded hole 15c. does not adversely affect That is, foreign matter is prevented from getting caught between the female threaded hole 15c and the male threaded portion 21b. That is, the radial gap between the guide portion and the cylindrical portion (upper cylindrical portion, lower cylindrical portion) is preferably smaller than the radial gap ΔMid between the female threaded hole 15c and the male threaded portion 21b.

Note that even if the size of the foreign matter does not fit in the space S formed at ΔMid, if the foreign matter has a size that fits in the space S formed at ΔMax, the foreign matter stays in the space S. It is possible to reduce the risk of locking the rotation of the screw due to foreign matter getting caught between the male screw portions 21b. That is, if the radial gap between the guide portion and the cylindrical portion (upper cylindrical portion, lower cylindrical portion) is smaller than the radial gap (distance ΔMax) between the female threaded hole 15c and the male threaded portion 21b, the effect of the present invention is exhibited. can.

Refrigerant in the can 45 is circulated to the valve chamber 29 by the operation of the flow control valve 1 and discharged to the outside of the flow control valve 1 through the first pipe T1. It does not remain in the can 45, and there is no need to periodically clean the inside of the can 45 to remove foreign matter. That is, according to the present embodiment, it is possible to provide the flow control valve 1 capable of ensuring smooth operation while reducing cost and maintenance effort.

1 flow control valve 10 valve main body 11 valve seat member 11e valve seat 15 guide stem 21 valve shaft 23 valve holder 24 coil spring 25 needle valve 26 spring bearing member 27 annular member 29 valve chamber 30 rotor 35 movable stopper 36 for valve closing direction valve opening directional movable stopper 50 stator 53 stator coil 55 valve closing direction fixed stopper 56 valve opening direction fixed stopper

Claims (6)

Can and
a valve body joined to the can;
Having a valve shaft arranged in a space surrounded by the can and the valve body and rotatable with respect to the valve body, and a guide stem fixed with respect to the valve body,
The valve stem is composed of an integral member and has a male threaded portion, an upper cylindrical portion arranged above the male threaded portion, and a lower cylindrical portion arranged below the male threaded portion ,
The guide stem includes a female threaded hole that is screwed into the male threaded portion, an upper end guide portion that is arranged above the female threaded hole and faces the upper cylindrical portion, and a lower cylindrical portion that is arranged below the female threaded hole. has a lower end guide portion facing the
Both the radial clearance between the upper end guide portion and the upper cylindrical portion and the radial clearance between the lower end guide portion and the lower cylindrical portion are larger than the radial clearance between the female threaded hole and the male threaded portion. small,
A flow control valve characterized by: The inner diameter of at least one of the guide portions is larger than the thread outer diameter of the male threaded portion,
The flow control valve according to claim 1, characterized in that: The inner diameter of the upper end guide portion is smaller than the inner diameter of the lower end guide portion,
3. The flow control valve according to claim 2, characterized in that: A movable stopper is fixed to the valve shaft by press fitting or screwing adjacent to the upper cylindrical portion ,
The guide stem has a fixed stopper that contacts the movable stopper when the valve shaft rotates by a predetermined amount.
The flow control valve according to any one of claims 1 to 3, characterized in that: The valve stem is made of metal, and the guide stem is made of resin.
The flow control valve according to any one of claims 1 to 4, characterized in that: further comprising: a rotor integrally rotatably connected and fixed to the valve shaft; and a stator fitted around the outer circumference of the can,
The flow control valve according to any one of claims 1 to 5, wherein the rotor and the stator constitute a stepping motor.

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