JP7550465B2 - Motor-operated valve - Google Patents

Description

The present invention relates to a motor-operated valve.

Conventionally, motorized valves are installed, for example, in the middle of a fluid piping system and are used to open and close the fluid flow path and control the flow rate (see Patent Document 1). In such motorized valves, the valve body is opened and closed by a stepping motor attached to the valve body, achieving precise flow rate control and sealing when the valve is closed.

JP 2019-143704 A

The fluid (refrigerant) flowing through the refrigeration cycle contains relatively hard foreign matter (metal powder, shavings, abrasives, sludge, etc.). Most of the foreign matter is captured by strainers installed in the path, but some of the fine foreign matter enters the motor-operated valve along with the fluid and passes between the valve body and the valve seat when the valve is opened.

If such a foreign object passes between the valve disc and the valve seat while the valve is closing, the foreign object may become trapped between the valve disc and the valve seat (this is called foreign object entrapment), causing deformation of the valve seat or valve disc, which may result in fluid leakage even when the valve disc is in a completely closed position.

In particular, in motor-operated valves equipped with a gear-type reduction mechanism with a high reduction ratio, the rotational speed of the stepping motor is reduced and converted into axial movement of the valve disc, which causes excessive surface pressure between the valve disc and the valve seat when the valve is closed. Therefore, if a foreign object becomes caught between the valve disc and the valve seat, it is pressed strongly against the valve disc or the valve seat, which causes scratches, dents, or other depressions on the contact surfaces of the valve seat or valve disc, making fluid leakage even more likely to occur.

The present invention was made in consideration of these problems, and aims to provide an electrically operated valve that is less likely to cause foreign matter to become caught between the valve body and the valve seat.

The motor-operated valve of the present invention comprises:
A valve body;
a valve body that moves in an axial direction by a driving force of a motor;
a valve seat unit;
the valve seat unit includes a valve seat on which the valve disc is seated, a valve seat member held so as to be movable relative to the valve body at least in the axial direction, and an elastic body disposed between the valve seat member and the valve body and capable of elastic deformation ;
the elastic body and the valve seat member are accommodated in an annular recess that opens in the axial direction of the valve body, and a stopper ring having an inner diameter smaller than an outer diameter of the valve seat member is fixed to an opening periphery of the annular recess,
During a valve closing operation, the valve body is seated on the valve seat and then comes into contact with the stopper ring .

The present invention provides an electrically operated valve that is less likely to become clogged between the valve body and the valve seat.

FIG. 1 is a vertical sectional view of a motor-operated valve according to a first embodiment. FIG. 2 is an enlarged vertical cross-sectional view showing the periphery of the valve seat unit. FIG. 3 is an enlarged vertical cross-sectional view showing the periphery of a valve seat unit according to the second embodiment.

Below, an embodiment of the motor-operated valve according to the present invention will be described with reference to the drawings. In this specification, the rotor side will be described as the upper side, and the valve body side will be described as the lower side.

First Embodiment
1 is a vertical cross-sectional view of a motor-operated valve 1 according to a first embodiment. The motor-operated valve 1 of the present embodiment is used, for example, to adjust the flow rate of a refrigerant in a refrigeration cycle. The axis of the motor-operated valve 1 is designated by L.

The motor-operated valve 1 of this embodiment is composed of a valve body 10 formed inside the valve chamber VC, a can 3 of a cylindrical shape with a top fixed to the valve body 10 via a base plate 11, a stepping motor 5 consisting of a stator 55 fitted onto the can 3 and a rotor 57 mounted inside the can 3, a cover 9 covering the periphery of the stator 55, a gear-type reduction mechanism 6 that reduces the speed of the rotational torque of the rotor 57 and transmits it, a valve body 4 that controls the amount of fluid passing through by moving it away from the valve seat 31a of the valve seat member 31, and a screw drive member (output shaft) 22 that converts the rotational movement of the output gear of the reduction mechanism 6 into linear movement via a screw feed mechanism 27 to drive the valve body 4. The can is a member having a cylindrical portion attached to the valve body side of the motor-operated valve so that the inside is sealed (the can 3 has a cylindrical portion with a bottom).

The stepping motor 5 has a stator 55 consisting of a yoke 51, a bobbin 52, a coil 53, etc., and a rotor 57 that is arranged inside the can 3 and can rotate freely with respect to the can 3, with a rotor support member 56 fixed to its upper inside. The stator 55 is fitted and fixed to the outside of the can 3, and is covered by a resin cover 9.

The bottomed cylindrical valve body 10 has an opening at its bottom that communicates with the internal valve chamber VC, and the first pipe T1 is connected to the opening side by brazing or the like, and the second pipe T2 is also connected by brazing or the like so as to communicate with an opening 12 formed on the side of the valve chamber VC. The axis of the second pipe T2 is O. The axis O is perpendicular to the axis L. Here, the pressure in the second pipe T2 is higher than the pressure in the first pipe T1.

A threaded bearing member 13 having a female thread portion 13a formed at the central lower end side is inserted into the upper part of the valve chamber VC of the valve body 10 and is fixed to the valve body 10 by press fitting or the like.

The reduction mechanism 6 has a sun gear 61 formed integrally with the rotor support member 56 on the inner periphery side of the rotor 57, a fixed ring gear 62 fixed via a thin-walled cylindrical body 66 fixed to the upper part of the valve body 10, a planetary gear 63 arranged between the sun gear 61 and the fixed ring gear 62 and meshing with them, a carrier 64 that rotatably supports the planetary gear 63, and a cylindrical output gear member 65 with a bottom that has teeth on its inner periphery that mesh with the planetary gear 63, which constitute a paradox planetary gear reduction mechanism. The number of teeth of the fixed ring gear 62 is set to be different from the number of teeth of the output gear member 65.

The shaft member 8 passes through the rotor support member 56 and the sun gear 61 and holds them rotatably, and the upper end of the shaft member 8 is supported by a support member 81 located inside the top of the can 3.

The upper part of the stepped cylindrical output shaft part 29 formed on the upper part of the screw drive member 22 is press-fitted into the center of the bottom of the output gear member 65, and the lower end of the shaft member 8 is press-fitted into the upper opening of this output shaft part 29.

The male threaded portion 22a formed on the lower part of the screw drive member 22 is screwed into the female threaded portion 13a of the screw bearing member 13. The rotational movement of the output gear member 65 (i.e., the rotor 57) is converted into linear movement along the axis L by the screw feed mechanism (conversion mechanism) 27 consisting of the male threaded portion 22a and the female threaded portion 13a.

The output shaft portion 29 is connected to the screw drive member 22 so that it can rotate together with it. When the output gear member 65 (rotor 57) rotates, the output shaft portion 29 and the screw drive member 22 rotate together and move linearly relative to the valve body 10 along the axis L.

The linear movement of the screw drive member 22 is transmitted to the intermediate shaft 7 via a ball joint 25 consisting of a ball 23 and a ball seat 24.

The cylindrical intermediate shaft 7 consists of an intermediate base 7a and an intermediate flange 7b connected to the upper end of the intermediate base 7a. An intermediate hole 7c is formed in the center of the intermediate flange 7b, and an expanded diameter opening 7d, which is larger in diameter than the intermediate hole 7c, is formed so as to connect to the intermediate hole 7c and open to the lower end of the intermediate base 7a. The lower end of the ball seat 24 is press-fitted into the intermediate hole 7c.

The cylindrical valve body 4 is composed of a valve body base 4a, the outer diameter of which is approximately equal to that of the intermediate base 7a, a valve body small diameter portion 4b connected to the upper end of the valve body base 4a, and a valve body large diameter portion 4c connected to the lower end of the valve body base 4a. The valve body small diameter portion 4b is press-fitted into the enlarged diameter opening 7d. A valve body conical surface 4d is formed at the lower part of the valve body large diameter portion 4c.

The cylindrical spring case 19 arranged around the intermediate shaft 7 and the valve body 4 is made up of a case enlarged diameter portion 19a, a case reduced diameter portion 19b, and an upper end flange portion 19c extending radially outward from the upper end of the case enlarged diameter portion 19a. The upper end flange portion 19c engages with the inner peripheral step of the valve body 10 and is fixed and held by the threaded bearing member 13. The case reduced diameter portion 19b slidably holds the outer periphery of the valve body base 4a.

The compression coil spring 26 is arranged in a compressed state with its lower end abutting against the step between the case enlarged diameter portion 19a and the case reduced diameter portion 19b, and its upper end engaging with the intermediate flange portion 7b of the intermediate shaft 7, thereby biasing the valve body 4 in the constantly open valve direction.

2 is an enlarged longitudinal cross-sectional view of the valve seat unit 30 and its periphery. The valve body 10 has a circular first opening 10a, a second opening 10b larger in diameter than the first opening 10a, and a third opening 10c larger in diameter than the second opening 10b, which are formed in the bottom surface of the valve chamber VC in this order and are coaxial with the axis L. The upper end of the first opening 10a constitutes an annular stopper portion 10d. The first opening 10a, the second opening 10b, and the third opening 10c form an annular recess that opens downward in the axial direction of the valve body 10. In addition, when the annular recess is a through hole, if the opening area on one side (here, the cross-sectional area of the third opening 10c) is larger than the opening area on the other side (here, the cross-sectional area of the first opening 10a), the through hole is considered to be "open" toward one side.

The third opening 10c is formed by the inner circumference of the downwardly protruding crimped cylindrical portion 10e (shown by a dotted line). A mounting opening 10f for mounting the first pipe T1 is formed radially outward of the crimped cylindrical portion 10e.

A ring-shaped valve seat member 31 and a resin or rubber O-ring (elastic body) 32 are arranged in the second opening 10b. The outer diameter of the valve seat member 31 is a specified amount smaller than the inner diameter of the second opening 10b. The upper end of the inner circumference of the valve seat member 31 forms the valve seat 31a. The O-ring 32 is made of, for example, NBR, H-NBR, EPDM, silicone rubber, fluororubber, urethane rubber, etc., and its Young's modulus is preferably in the range of 0.1 to 10 MPa.

An annular member 33 is placed in the third opening 10c. The upper surface of the annular member 33 near the inner circumference protrudes to form an annular protrusion 33a. The valve seat member 31, O-ring 32, and annular member 33 constitute the valve seat unit 30.

When assembling the valve seat unit 30, the valve seat member 31, O-ring 32, and annular member 33 are inserted in this order into the inside of the crimped cylindrical portion 10e from the lower side of the valve body 10, and the lower end of the crimped cylindrical portion 10e (the opening periphery of the annular recess) is crimped (plastically deformed) inward as shown in FIG. 2, reducing the diameter below the outer diameter of the annular member 33. As a result, the upper surface of the annular member 33 abuts against the step between the first opening 10a and the second opening 10b, and the annular member 33 is fixed to the valve body 10 and integrated, and the valve seat member 31 and the O-ring 32 are prevented from coming off. The fixed annular member 33 biases the valve seat member 31 upward via the O-ring 32, and it is held in abutment against the step between the first opening 10a and the second opening 10b. In this state, the O-ring 32 is compressed in the direction of the axis L by the valve seat member 31 and the O-ring 32. The annular protrusion 33a of the annular member 33 abuts against the inner periphery of the O-ring 32, preventing the O-ring 32 from falling off. All of the components of the valve seat unit 30 can be assembled from the lower side of the valve body 10.

(Operation of motor-operated valve)
When a control device (not shown) supplies a valve-closing control signal with a predetermined number of pulses to the stator 55 to rotate the rotor 57 of the stepping motor 5 in one direction, the rotational speed is input from the sun gear 61 to the reduction mechanism 6, and the rotational speed reduced by the reduction mechanism 6 is transmitted to the screw drive member 22 via the output shaft 29. When the screw drive member 22 rotates in one direction, the female threaded portion 13a and the male threaded portion 22a screw relative to each other, and the screw drive member 22 moves downward in the direction of the axis L according to the rotational speed. The thrust of the screw drive member 22 urges the intermediate shaft 7 downward via the ball joint 25, and the intermediate shaft 7 descends against the urging force of the compression coil spring 26.

As the intermediate shaft 7 descends, the valve body 4 descends, and the valve body cone surface 4d seats on the valve seat 31a of the valve seat member 31, closing the second opening 10b (see Figure 2). This interrupts the flow of fluid between the pipes T2 and T1 across the valve chamber VC.

The valve-closing control signal input from a control device (not shown) to the stepping motor 5 includes a number of pulses that allow the rotor 57 to further rotate by a certain angle after the valve body conical surface 4d seats on the valve seat 31a, taking into account play in the drive path. Therefore, the valve body 4 continues to descend even after the valve body conical surface 4d seats on the valve seat 31a.

If the valve seat 31a were integral with the valve body 10, the valve body conical surface 4d would be biased toward the valve seat 31a even after contact, creating a high surface pressure between them. In particular, if the motor-operated valve 1 has a gear-type reduction mechanism 6, the surface pressure between the valve body conical surface 4d and the valve seat 31a would be excessive. In such a situation, if a hard foreign object is present between the valve body conical surface 4d and the valve seat 31a, indentations or scratches will be created on at least one of the valve body conical surface 4d and the valve seat 31a, which may result in fluid leakage when the valve is closed.

According to this embodiment, after the valve body conical surface 4d seats on the valve seat 31a, the O-ring 32 elastically deforms in response to the descent of the valve body 4, so that the valve seat 31a descends while remaining in contact with the valve body conical surface 4d. The elastic force generated by the elastic deformation of the O-ring 32 presses the valve seat 31a and the valve body conical surface 4d together, but this elastic force is considerably smaller than the driving force that the valve body 4 receives. For this reason, the surface pressure between the valve body conical surface 4d and the valve seat 31a is relatively small, and even if a hard foreign object is present between the valve body conical surface 4d and the valve seat 31a, the occurrence of indentations or scratches is suppressed, thereby suppressing fluid leakage when the valve is closed.

In addition, because the outer diameter of the valve seat member 31 is smaller than the inner diameter of the second opening 10b, the valve seat member 31 can move in the direction perpendicular to the axis within the second opening 10b. Therefore, even if the axes of the valve body 4 and the valve seat member 31 are misaligned, the valve seat member 31 is automatically centered in accordance with the descending valve body cone surface 4d, thereby ensuring an appropriate seating position without increasing the assembly tolerance of the parts, and suppressing fluid leakage.

As the valve body 4 descends, the valve body cone surface 4d seats on the valve seat 31a, and then the valve body cone surface 4d comes into contact with the stopper portion 10d, thereby preventing damage to the valve seat unit 30 due to over-rotation of the rotor 57.

On the other hand, when a valve opening control signal is supplied to the stator 55 from a control device (not shown) to rotate the rotor 57 of the stepping motor 5 in the other direction, the screw drive member 22 moves upward in the direction of the axis L via the reduction mechanism 6 and the screw feed mechanism 27. As a result, the intermediate shaft 7 rises in accordance with the biasing force of the compression coil spring 26.

When the valve body 4 rises together with the intermediate shaft 7, the valve seat member 31 rises following the valve body 4 because it is urged upward by the elastic force of the compressed O-ring 32, but stops rising when it comes into contact with the step between the first opening 10a and the second opening 10b. As the valve body 4 rises further, the valve body conical surface 4d separates from the valve seat 31a, opening the second opening 10b. This allows fluid to flow from the second pipe T2 through the valve chamber VC to the first pipe T1.

Second Embodiment
3 is an enlarged longitudinal sectional view of the valve seat unit 30A according to the second embodiment. The valve body 10A and the valve seat unit 30A of this embodiment are different from those of the first embodiment. The rest of the configuration is the same as that of the above-mentioned embodiment, so a duplicated description will be omitted. The valve body 10A and the valve seat unit 30A can also be attached to the motor-operated valve 1 shown in FIG.

The valve body 10A has a circular first opening 10Aa and a second opening 10Ab, which is smaller in diameter than the first opening 10Aa, formed in that order on the bottom surface of the valve chamber VC and are coaxial with the axis L. The first opening 10Aa and the second opening 10Ab form an annular recess that opens upward in the axial direction of the valve body 10A. A stopper ring 33A made of brass or the like is fixed inside the first opening 10Aa. The inner periphery of the upper end of the stopper ring 33A forms the annular stopper portion 33Aa.

An inner cylindrical portion 10Ac is formed extending upward from the inner circumference of the lower end of the second opening 10Ab, and therefore an annular groove 10Ad is formed between the outer circumference of the inner cylindrical portion 10Ac and the inner circumference of the second opening 10Ab.

The valve seat member 31A is composed of a thick cylindrical portion 31Aa and a thin cylindrical portion 31Ab connected together. The thick cylindrical portion 31Aa and the thin cylindrical portion 31Ab have the same outer diameter, which is a predetermined amount smaller than the inner diameter of the second opening 10Ab. The inner diameter of the thin cylindrical portion 31Ab is a predetermined amount larger than the outer diameter of the inner cylindrical portion 10Ac. Therefore, when the thin cylindrical portion 31Ab is placed in the annular groove 10Ad together with the O-ring 32A, it can move in the direction perpendicular to the axis.

The inner diameter of the thick cylindrical portion 31Aa is smaller than the inner diameter of the stopper ring 33A and smaller than the inner diameter of the thin cylindrical portion 31Ab. It is preferable that the inner diameter of the thick cylindrical portion 31Aa and the inner diameter of the second opening 10Ab are approximately equal. The upper inner circumference of the thick cylindrical portion 31Aa forms the valve seat 31Ac. The valve seat member 31A, O-ring 32A, and stopper ring 33A form the valve seat unit 30A.

When assembling the valve seat unit 30A, the O-ring 32A is inserted into the annular groove 10Ad from above the valve body 10A, and then the thin-walled cylindrical portion 31Ab of the valve seat member 31A is inserted from above. The stopper ring 33A is then fixed to the first opening 10Aa (the opening periphery of the annular recess) by press-fitting, welding, or other means, and integrated with the valve body 10A. This prevents the valve seat member 31A from coming loose. All of the components of the valve seat unit 30 can be assembled from above the valve body 10A.

When the valve seat unit 30A is attached to the valve body 10A, there is a gap between the bottom surface of the thick cylindrical portion 31Aa of the valve seat member 31A and the top end of the inner cylindrical portion 10Ac. When the valve is open, the valve seat member 31A is urged upward by the elastic force of the O-ring 32A and is held in contact with the bottom surface of the stopper ring 33A.

(Operation of motor-operated valve)
1, when the rotor 57 of the stepping motor 5 is driven to rotate in one direction, the intermediate shaft 7 descends and the valve body 4 descends, so that the valve body conical surface 4d seats on the valve seat 31Ac of the valve seat member 31A, closing the second opening 10Ab (see FIG. 3). This interrupts the flow of fluid between the pipes T2 and T1 across the valve chamber VC.

According to this embodiment, after the valve body conical surface 4d is seated on the valve seat 31Ac, the valve seat member 31A is pushed downward in response to the descent of the valve body 4, and the O-ring 32A is elastically deformed, so that the valve seat 31Ac descends while remaining in contact with the valve body conical surface 4d. The elastic force generated by the elastic deformation of the O-ring 32A presses the valve seat 31Ac and the valve body conical surface 4d, but this elastic force is considerably smaller than the driving force received by the valve body 4. Therefore, the surface pressure between the valve body conical surface 4d and the valve seat 31Ac is relatively small, and even if a hard foreign object is interposed between the valve body conical surface 4d and the valve seat 31Ac, the occurrence of indentations or scratches is suppressed, thereby suppressing fluid leakage when the valve is closed.

In addition, since the valve seat member 31A can move in a direction perpendicular to the axis within the second opening 10Ab, even if the axes of the valve body 4 and the valve seat member 31A are misaligned, the valve seat member 31A is automatically centered in accordance with the descending valve body conical surface 4d, thereby ensuring an appropriate seating position without increasing the assembly tolerance of the parts, and suppressing fluid leakage. However, the valve seat member 31A may also be held so that it can slide only in the axial direction within the second opening 10Ab.

The descending valve body 4 is stopped by the valve body cone surface 4d abutting against the stopper portion 33Aa, which prevents damage to the valve seat unit 30 due to over-rotation of the rotor 57.

Meanwhile, when the valve body 4 rises together with the intermediate shaft 7 by supplying a valve-opening control signal to the stator 55 from a control device (not shown), the valve seat member 31A rises following the valve body 4 because it is urged upward by the elastic force of the compressed O-ring 32A, but stops rising when it comes into contact with the underside of the stopper ring 33A. As the valve body 4 rises further, the valve body conical surface 4d separates from the valve seat 31Ac, opening the second opening 10Ab. This allows fluid to flow from the second pipe T2 through the valve chamber VC to the first pipe T1.

1 Electric valve 10, 10A Valve body 3 Can 4 Valve body 5 Stepping motor 53 Coil 55 Stator 57 Rotor 6 Speed reduction mechanism 8 Shaft member 9 Cover 30, 30A Valve seat unit 31, 31A Valve seat member 32, 32A O-ring (elastic body)
33 Annular member 33A Stopper ring VC Valve chamber T1 First pipe T2 Second pipe L Axis

Claims (3)

A valve body;
a valve body that moves in an axial direction by a driving force of a motor;
a valve seat unit;
the valve seat unit includes a valve seat on which the valve disc is seated, a valve seat member held so as to be movable relative to the valve body at least in the axial direction, and an elastic body disposed between the valve seat member and the valve body and capable of elastic deformation ;
the elastic body and the valve seat member are accommodated in an annular recess that opens in the axial direction of the valve body, and a stopper ring having an inner diameter smaller than an outer diameter of the valve seat member is fixed to an opening periphery of the annular recess,
During a valve closing operation, the valve body is seated on the valve seat and then comes into contact with the stopper ring.
A motor-operated valve. The valve seat member is held movably in a direction perpendicular to the axial direction relative to the valve body.
2. The motor-operated valve according to claim 1 . The driving force of the motor is transmitted to the valve body via a gear-type reduction mechanism.
3. The motor-operated valve according to claim 1 or 2 .

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