JP2002122258A - Electric control valve and assembly method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric control valve capable of preventing biting into a valve seat while enabling minute flow regulation by forming an angle of a tapered part of a needle into an acute angle and establishing a valve closing position precisely. SOLUTION: A female screw member 11 in contact with the valve seat 19 when the valve is completely closed holds a needle valve 13 slidably to reduce a load of the needle valve 13 when the valve is completely closed so that biting into the valve seat is prevented while enabling minute flow regulation by forming the angle of the tapered part into the acute angle and matching of a stepping motor is done when the valve is completely closed to establish the valve closing position precisely.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric control valve which is incorporated in refrigeration, refrigeration and air-conditioning equipment such as a heat pump type air conditioner and a refrigerator, and is used for controlling a flow rate of a refrigerant, and particularly includes a stepping motor as a driving source. Also, the present invention relates to an electric control valve having a needle valve as a flow control valve and a method for assembling the same.

[0002]

2. Description of the Related Art Conventionally, as an electric control valve as described above, the one shown in FIG. 5 has been proposed. In FIG. 5, reference numeral 14 denotes a valve body of an electric control valve. The valve body 14 is provided with a first opening 22 connected to a flow path of a first joint 21a immediately below an axial direction thereof. A second opening 23 connected to the flow path of the second joint 21b is provided on a side portion in the vicinity, and the valve chamber 15 is formed so as to connect the first opening 22 and the second opening 23 from above the valve body 14. Have been. The upper part of the valve body 14 is covered with a can 1 provided with a lid 9 at the lower part, and a rotor 10 of a stepping motor 20 is provided inside the can 1. The rotor 10 is made of synthetic resin and has a pin 24 provided at the center thereof.
5 is inserted. Needle valve 13 at the lower end of pin 24
The needle valve 13 is provided with a first valve as a valve seat.
A control valve is constituted in cooperation with the opening 22. Reference numeral 33 denotes a rotation preventing step.

[0003] A male screw 25 is formed on the outer periphery of the protruding portion 10 s extending below the rotor 10, and a female screw 26 screwed to the male screw 25 is formed on the inner wall of the valve body 14. Therefore, when the rotor 10 rotates, the female screw 26 is fixed, so that the rotor 10, that is, the needle valve 13 moves up and down in the first opening 22 to control the flow rate of the refrigerant.

A support recess 2 is provided at the center of the upper lid 27 of the can 1.
8 is provided, the upper projection 30 of the guide member 29 is fitted into the support recess 28, and the center hole 2 of the guide member 29 is provided.
9a and the upper end of the pin 24 are fitted so as to be vertically movable and rotatable.

The spring receiver 3 is provided on the outer periphery of the guide member 29.
1 is formed, and a spring 32 is contracted between the spring receiver 31 and the lower surface of the concave fitting portion of the rotor 10. Further, the stator coil 17 of the stepping motor 20 is fixed to the cylindrical outer periphery of the can 1, and the connector 34
Is connected to the outside. The stator coil 17 is formed by an upper coil 17a and a lower coil 17b.

In the needle valve type electric expansion valve having the above-described structure, the rerotor 10 is rotated by energizing the stator coil 17. By screwing a male screw 25 formed on the protrusion 10s of the rotor 10 with a female screw 26 formed on the inner wall of the valve body, the pin 24 integrally formed with the rotor 10 also moves up and down while rotating together. Thereby, the needle valve 13 formed on the pin 24 moves up and down, moves up and down in the first opening 22, and controls the flow rate of the refrigerant.

[0007]

In the above-mentioned conventional electric control valve, an electric needle valve is used for controlling the flow rate of the refrigerant.

In the case of a needle valve type electric control valve having a fully open function, the tapered portion of the needle valve must be brought into contact with the valve seat, and the needle valve bites into the valve seat by a vertical force. In order to prevent this, the tapered portion needs to be sufficiently large, for example, 60 degrees. Further, the needle root diameter D1 is the diameter D of the valve hole.
Must be smaller than 0 (D0> D1).

As a result, in the needle valve type,
The valve characteristic at the start of valve opening will be a sudden rise. Further, if a slight clearance is provided between the needle and the valve seat in order to prevent the bite, there is a possibility that the clearance alone may exceed the control range of the minute refrigerant flow rate. For this reason, there is a problem that the needle valve type cannot be applied to a refrigeration cycle requiring minute refrigerant flow rate control. The present invention is to solve such a problem of the conventional example.

[0010]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a can as a case, a valve body having a valve chamber and a valve seat disposed inside the can, A rotor of a stepping motor attached to the main body, and an electric control valve including a needle that functions as a needle valve when driven by the rotor of the stepping motor in the direction of coming into contact with and separating from the valve seat; A male screw member is integrally formed, a cylindrical female screw member having a female screw is provided in the valve chamber so as to be vertically slidable, and a guide for preventing the female screw member from rotating is fixed to the valve chamber. After contacting the valve seat, the lower end flat portion of the female screw member abuts the valve seat to stop the rotation of the rotor of the stepping motor by frictional force,
After completely closing the needle valve in contact with the valve seat,
The female screw member is configured to abut on the valve seat to be in a valve closed state as a valve.

In the method for assembling an electric control valve according to the present invention, a female screw member, a guide and a needle valve are previously mounted in a valve chamber of a valve body, and the needle valve and the female screw member are set to a completely closed state. In order to solve the problem, the stator of the stepping motor is fixed at a position where the rotor of the stepping motor stops rotating so as to cover the valve body.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows the entirety of an electric control valve according to an embodiment of the present invention. This electric control valve also has a can 1, a stator coil 17, a first joint 21a, 2 joint 21b, valve body 14, needle valve 1
3, a valve seat 19, a male screw 12a, a female screw 11a, a connector 34, and the like.

The electric control valve of this embodiment differs from the conventional control valve in the following configuration. Male thread 12
“a” is provided on the outer periphery of a shaft-like male screw member 12 that is integrated with the rotor 10 of the stepping motor by insert molding. The female screw 11a is formed on the inner surface of a cylindrical female screw member 11 provided at the center of the rotor 10 of the stepping motor. At the lower end of the female screw 11a of the female screw member 11 shown in FIG. 2, a space 11b for accommodating the needle valve 13 and the valve spring 7 having a smaller diameter than the female screw 11a is provided.

A guide 6 that allows the female screw member 11 to slide up and down without rotating with the rotor 10 of the stepping motor is slidably provided in a concave portion 11c formed at two places on the outer surface of the head of the female screw member 11. The other end 6 a of the guide 6 is fixed to the valve body 14. Female screw member 11
A mounting spring 8 that pushes up the female screw member 11 toward the rotor 10 of the stepping motor is inserted between the valve body 14 and the valve body 14. The needle valve 13 is inserted into the center hole 11 d of the female screw member 11, and a valve spring 7 is provided between the tip of the male screw and the upper part of the needle valve 13, and a step provided on the upper part of the reneedle valve 13 by the force of the valve spring 7. Part 13a and female screw member 11
The needle valve 13 is pressed against the stepped portion of the center hole 11d. A plurality of grooves 11f are provided at a distal end portion 11e of the female screw member 11 which comes into contact with the valve body 14 so that the refrigerant can easily pass therethrough.

In FIG. 1, a rotor shaft 12b is provided on the opposite side of the male screw portion of the male screw member 12, and a bearing 2 is provided between the upper convex portion 1a of the can and the rotor shaft 12b. A rotor shaft 12b is inserted into the center hole of the bearing 2 so as to be vertically slidable, and a corrugated leaf spring 3 is provided between the bearing 2 and the rotor 10 of the stepping motor.

The groove 1 on the needle valve 13 side of the female screw member 11
1 f acts as a stopper of the female screw member 11 by a frictional force between the female screw member 11 and the valve body 14 by the rotational force of the rotor 10.

The stator 17 of the stepping motor includes a pair of upper and lower coils 17a and 17b and a plurality of magnetic poles 17c and 17d magnetized by each coil. The coils 17a and 17b and the magnetic poles 17c and 17d are integrally formed with the outer box 4 in advance when assembling the stepping motor.

In the above configuration, when the rotor 10 of the stepping motor rotates, the male screw member 12 integrally formed with the rotor 10 rotates, and the force of the mounting spring 8 is reduced by the screw action with the female screw member 11 that is not rotated by the guide 6. The female screw member 11 and the needle valve 13 move downward to control the distance between the needle valve 13 and the valve seat 19, and the valve opening area changes.

When the rotor 10 of the stepping motor is rotated in the valve closing direction from this state, the female screw member 11 and the needle valve 13 are lowered and come into contact with the valve seat 19 to be in a "valve closed" state. At this time, the weak load of the valve spring 7 is applied to the needle valve 13.
In this embodiment, the load is designed so that the valve seat 19 does not bite even if the needle angle is acute. This load acts so as to keep the valve closed after the needle valve 13 contacts the valve seat 19 and until the rotation of the rotor 10 of the stepping motor is stopped. Contact portion 13h of female screw member 11 with needle valve 13
A slight gap Lc is formed between the needle valve 13 and the valve spring receiving step 13a of the needle valve 13.

When the rotor 10 of the stepping motor is further rotated in the valve closing direction after the needle valve 13 is in the "valve closed" state, the lower end surface of the female screw member 11 is closed by the lower valve chamber 16a of the valve body 14. It comes into contact with the seat surface, and the state is "complete valve closed". Next, the corrugated leaf spring 3 is deformed to apply a strong load to the rotor 10 and the bearing 2 of the stepping motor, and the rotor 10 stops rotating.

Next, a method of assembling the electric control valve will be described. The valve body 14 has a fluid first joint 2.
1a, second joint 21b, needle valve 13 and female screw member 1
1, a guide 6, a mounting spring 8, and a valve chamber 15 for housing the valve spring 7 are provided on a central axis of a valve seat 19. Further, a mounting hole 5 for fixing the stator coil 17 of the stepping motor at a fixed position is provided on the outer peripheral surface in advance.

In FIG. 2, the center hole 1 of the female screw member 11 is shown.
The needle valve 13 is inserted into 1b, and then the valve spring 7 is inserted. Next, the guide 6 is attached to the female screw member 11 by inserting the rotation stopper 6b of the guide 6 into the two rotation stopper recesses 11c of the large diameter portion 11g of the female screw member 11. Thereafter, the mounting spring 8 is inserted into the small-diameter portion 11h of the female screw member 11 from below with the guide 6. And caulking part 6 of guide 6
and the caulking portion 20a of the valve chamber 15 is caulked. The male screw member 12 is placed so as to cover the valve chamber 15, and the male screw member 12 is rotated by hand. Next, the corrugated leaf spring 3 and the bearing 2 are inserted into the shaft portion 12b of the male screw member 12. Finally, the can 1 is covered, and the lower end is hermetically welded to the lid 9 of the valve body 14.

The rotor 10 of the stepping motor is integrally formed with a male screw member 12 by insert molding. The screw portion 12a of the male screw member 12 is connected to the screw portion 11a of the female screw member 11 from the center of the guide 6 by the stepping motor. The rotor 10 is inserted while rotating by hand. Next, the corrugated leaf spring 3 and the bearing 2 are inserted into the shaft portion 12b of the male screw member 12, and the can 1 is combined with the valve body 14.

Rotor 1 of stepping motor by jig
0 is rotated from the outside of the can 1 to set the closing base point of the electric control valve, and the swaging portion 20a with the guide 6 of the main body 14 is swaged and fixed. Thereafter, the can 1 is hermetically welded to the lid 9 attached to the valve body 14.

By assembling the electric control valve by such assembling means, the valve closing base point can be set while the female screw member 11 is in contact with the valve seat 19. It is possible to eliminate an error due to a large backlash or a base point error caused by backlash of the screw mechanism.

In the case of this embodiment, when the needle valve is in the "fully closed" state, the flat surface of the distal end (lower end) of the female screw member 11 is in contact with the valve seat 19 of the valve body 14. Therefore, the angle θs of the tip valve portion 13e of the needle valve 13
Even if the flow rate can be controlled by setting a small value (see FIG. 3) to, for example, 6 degrees, it is possible to prevent biting into the valve seat.

In this embodiment, when the needle valve 13 is in the "fully closed" state, the female screw member 11 contacts the valve seat 19 and applies a load acting on the needle valve 13 and the valve seat to the female screw member 11.
, The needle valve load when the needle valve 13 is in the “complete valve closed” state is reduced to a small load (“refrigerant introduction pressure” − “refrigerant discharge pressure”) / “spring force of the valve spring 7”. As a result, the valve seat 1 of the needle valve 13
9 can be prevented.

The curve shown in FIG. 4 shows the load characteristics of the needle valve when θn = 6 °, and the line indicates “needle valve contact load” Wi = “valve withdrawal load” W0.
The line indicates the thrust generated by the stepping motor, and the line indicates the contact (load) load on the needle valve.
Here, the contact (square load) load on the needle valve is “introduction pressure of refrigerant” − “discharge pressure of refrigerant” + “spring force of valve spring”. Points indicate inflection points.

In this embodiment, as described above, when the needle valve 13 is in the "complete valve closed" state, the female screw member 11 bears the load acting on the needle valve 13 due to the female screw member 11 contacting the valve seat 19. With this configuration, the load on the needle valve 13 when the needle valve 13 is in the “complete valve closed” state can be set to the point indicated by the reference symbol S. As a result, the "valve withdrawal load" W0 can be suppressed to a small load ("refrigerant introduction pressure"-"refrigerant discharge pressure" + "valve spring force"), and the tip valve portion of the needle valve 13 is made obtuse. The valve seat 1 of the needle valve 13 can be set to
9 can be prevented from biting.

[0030]

As described in detail above, according to the present invention,
The following effects can be obtained. (1) Even if the tip valve portion of the needle is set at an acute angle so that the minute flow rate control can be performed, it is possible to prevent the needle from biting into the valve seat. (2) The collision noise in the rotation stop mechanism can be reduced, and the noise of the electric control valve can be further reduced by the corrugated leaf spring. (3) Since the flat surface of the female screw member is used as a reference when setting the base point of the stepping motor, the durability is high and the deterioration is extremely small. (4) Since the stopping position of the rotation stopping mechanism can be adjusted at the same time, the assembling step can be omitted. (5) When the valve is completely closed, the pressing force generated on the needle valve and the valve seat is very small, so that the deformation of the valve seat is small.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view of an electric control valve according to an embodiment of the present invention, and FIG. 1B is a partially enlarged view of a needle valve.

FIG. 2 is an enlarged sectional view of a main part of the female screw member of FIG.

FIG. 3 is an enlarged sectional view of a part of a needle valve and a valve seat of FIG. 1;

4 is a graph showing a relationship between a contact load (horizontal axis) of a needle valve of the electric control valve of FIG. 1 and a valve pull-out load (vertical axis).

FIG. 5 is a sectional view of a conventional electric control valve.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Can 2 Bearing 3 Corrugated leaf spring 4 Outer box 5 Stator coil mounting hole 6 Guide 7 Valve spring 8 Mounting spring 9 Lid 10 Stepper motor rotor 11 Female screw member 11a Female screw 12 Male screw member 12a Male screw 13 Needle valve 14 Valve body 15 Valve Chamber 16a Lower valve chamber 17 Stator coil 17a Upper coil 17b Lower coil 17c Downward magnetic pole 17d Upward magnetic pole 19 Valve seat 20 Tube section 21a First joint 21b Second joint

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Nobuo Tsubaki, Inventor 535 Sasai, Sayama-shi, Saitama Prefecture Sagimiya Manufacturing Co., Ltd. 72) Inventor Toru Sekiya 535 Sasai, Sayama City, Saitama Prefecture Inside the Sayama Works, Sayama Works (72) Inventor Morio Kaneko 535 Sasai, Sayama City, Saitama Prefecture Inside the Sayama Works, Sayama Works F Term 3H062 AA02 AA15 BB24 BB28 BB31 CC02 DD01 EE06 GG04 GG06 HH04

Claims (5)

[Claims] 1. A can as a case, a valve body having a valve chamber and a valve seat disposed inside the can, a stepping motor rotor attached to the valve body, and a rotor of the stepping motor. An electric control valve provided with a needle that functions as a needle valve by being driven in the direction of coming into contact with and separating from the valve seat by providing a male screw member molded integrally with the rotor of the stepping motor and having an external thread formed on the outer peripheral surface. A cylindrical female screw member formed on the inner peripheral surface with a female screw to be screwed with the male screw is provided together with a mounting spring in the valve chamber, and inside the female screw member,
A needle valve is provided, and at the time of the valve closing stroke, the flat lower end surface of the female screw member abuts on a valve seat and the needle valve abuts on the valve seat before the needle valve is completely closed. An electric control valve, wherein the needle valve is configured to be closed. 2. The motor-operated control valve according to claim 1, wherein a guide that prevents rotation of the female screw member in the valve chamber and enables vertical sliding is fixed to the valve body. 3. The electric control valve according to claim 1, wherein a valve spring having a weak spring force for urging the needle valve in the valve seat direction is provided inside the female screw member. 4. A corrugated leaf spring is interposed between an upper end of a male screw member integrally formed with the rotor of the stepping motor and a bearing, and the corrugated leaf spring is elastically deformed when the needle valve is completely closed. The electric control valve according to any one of claims 1 to 3, wherein the electric control valve is configured to absorb a rotor rotation torque of the stepping motor. 5. A position where the rotor assembly of the stepping motor is previously mounted on the valve body, the needle valve, the guide, and the female screw member are set to the completely closed state, and the rotation stopping mechanism is in the rotation stopped state. Is fixed with respect to the valve body with a jig, and the stator coil of the stepping motor, whose magnetization base point is aligned and fixed with respect to the fixed position of the valve body, is fixed from above the can of the rotor assembly to the fixed position of the valve body. A method for assembling an electric control valve, characterized in that it is covered so as to match.