JPH10292876A - Electronic expansion valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent continuous striking sound at the initializing control time and to prevent the reduction of the service life without increasing the external form size at a low cost. SOLUTION: At the abutting parts of a stopper 5 provided at the upper part of a valve main body and a projection 4 provided at the lower part of a rotor 3b, electrodes 5a and 4a are provided respectively, and the drive of a pulse motor is made to stop when the communication between both electrodes is detected. Consequently, when a flow passage 1c is closed fully, the rotation driving of the rotor is stopped, regardless of the position of a valve body 1e before the initializing control is carried out, and the projection 4 never strikes to the stopper repeatedly, and the continuity of the striking sound in the initializing control condition is prevented at a low cost without making the external form size larger, so as to prevent the reduction of the service life and to improve the reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic expansion valve provided in a refrigerant circuit, for example, as a decompression mechanism of an outdoor unit, and more particularly to an electronic expansion valve which detects a fully closed state and stops driving the valve.

[0002]

2. Description of the Related Art Conventionally, an electronic expansion valve provided in a refrigerant circuit as a decompression mechanism of an outdoor unit is, for example, as shown in a partially exploded perspective view of FIG. A pulse motor 3, which drives the valve and includes a coil 3a, a rotor 3b housed in a case 6, and a permanent magnet 3c, etc., is disposed above, and converts the rotational motion of the rotor 3b into a linear motion in the axial direction. The valve body in the valve body 1 is driven by this linear movement. And the rotor 3b
A protrusion 4 is provided at the lower part of the valve body 1 to protrude in the axial direction, and a stopper 5 that contacts the protrusion 4 at the upper part of the valve body 1 and restricts the rotation of the rotor at the fully closed point of the flow path of the valve body 1 is provided. Provided.

More specifically, as shown in a sectional side view of a main part of FIG. 6, the valve body 1 is formed with a first passage 1a opened on a side surface and a second passage 1b opened on a lower surface. The passages 1a and 1b communicate with each other via a flow path 1c, and a valve seat 1d is provided in the flow path 1c. The upper portion of the valve body 1 is hermetically covered by the case 6, and a coil 3 a is arranged on the outer periphery of the case 6. A rotor 3b is arranged inside the case 6, and a permanent magnet 3c is attached to an outer peripheral portion of the rotor 3b. A pulse current or the like is input to the coil 3a,
The rotor 3b is rotationally driven by attracting and repelling the permanent magnet 3c. The axial center portion of the rotor 3b is provided with a circular shaft hole 3b1 having an opening at the lower end and a female screw formed on the inner peripheral surface and extending in the axial direction, and a concave portion 3b2 opening at the upper end and extending in the axial direction. Have been.

On the other hand, a concave portion 1f is formed in the center of the upper end of the valve body 1, and a cylindrical fixed bearing 1g is attached to the concave portion 1f, and a male screw formed on the outer periphery of the fixed bearing 1g. The inner peripheral surface of the circular shaft hole 3b1 of the rotor 3b is screwed to the portion. The circular shaft hole 3 of the rotor 3b
Partition wall 3b3 between b1 and recess 3b2 and fixed bearing 1g
A valve body 1e for controlling the flow rate of the refrigerant flowing through the flow path 1c by changing the opening degree of the valve body 1d by coming into contact with and separating from the valve seat 1d through the valve body 1d. A valve portion 1e1 is formed at the lower end, and a washer 7 for preventing the valve body 1e from coming off is attached to the upper end. Also, the valve element 1e
A stepped portion 1e2 is formed at an intermediate portion between the stepped portion 1e2 and a coil spring 8 is interposed between the stepped portion 1e2 and the partition wall 3b3. The coil spring 8 presses and urges the valve element 1e downward.

In the above-mentioned electronic expansion valve, the rotary motion of the rotor 3b of the pulse motor 3 is converted into the axial linear motion of the valve body 1e, and the pulse current input to the coil 3a of the pulse motor 3 is controlled by the control unit. By doing, the valve element 1
It is intended to control the amount of movement of e to control the degree of opening between the valve body 1e and the valve seat 1d. Now, when the valve 1e is moved to control the opening to a predetermined degree, the control section controls the coil 3a to supply the necessary number of pulse currents to the coil 3a from the current position of the valve 1e to the predetermined position. There is a need. However, the current position of the valve element 1e at the beginning of operation is unknown.

Therefore, in order to clarify the current position of the valve element 1e, in the initial stage of the operation, as initializing control, the number of pulses necessary to exceed the full stroke from the fully open position to the fully closed position is input, and the valve is always fully closed. It is in a state. At this time, even when the position of the valve element 1e before the initialization control is near the fully closed position, the same number of pulses as in the case of the fully open position must be input. As a result, even after the protrusion 4 hits the stopper 5 that restricts the rotation of the rotor 3b, an excessive pulse current flows through the coil 3a, so that the repulsion and the attraction by the permanent magnet 3c occur alternately. However, since the projection 4 and the stopper 5 repeat the collision operation, not only the collision sound is repeatedly generated, but also the bite and wear due to the friction between the valve element 1e and the valve seat 1d occur, the life is shortened, and the failure frequently occurs. A problem could have occurred.

In order to solve this problem, the protrusion 4 is made of resin, or is returned to the fully open position when stopped, and the valve body 1e is moved from the fully open position to the fully closed position during the initialization control. Techniques have been devised for reducing the number of pulse currents and reducing the repetition of the collision operation. However, in the former case, the life is shortened because the resin material is deformed by heat. In the latter case, the number of collisions increases if the rotor 3b rotates for some reason, such as during transportation, and the position of the valve body 1e is shifted. There was a problem that it would.

Therefore, as shown in FIG. 4, the permanent magnet 3c is extended upward, and at the top of the case 6,
A rotation detecting means such as a magnetic head for detecting the rotation of the permanent magnet 3c is provided to detect the number and direction of the actual rotation of the rotor, and to add the number of rotations and the direction to the value previously stored in the storage unit and re-execute. A method of relatively knowing the position of the valve element 1e by storing it has been considered. But with this method,
Since the permanent magnet 3c must be extended upward or a rotation detecting means such as a magnetic head must be attached, not only the outer dimensions are increased, but also the cost is increased, and it has not been possible to meet the demand for miniaturization and cost reduction.

[0009]

SUMMARY OF THE INVENTION The present invention has solved the above-mentioned problems, and has prevented the reduction of the life by preventing the collision sound during initialization control from being continued without increasing the external dimensions and using an inexpensive method. It is intended to provide an electronic expansion valve.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a valve seat in a flow passage communicating between a first passage and a second passage provided in a valve body. A valve element that opens and closes the flow path by contacting and separating is provided, and the valve element converts the rotational motion of the rotor of the pulse motor, which is rotationally driven by flowing a pulse current from the control unit to the coil, into a linear motion in the axial direction. Converted,
The rotor is driven by this linear motion, and a projection is provided on the lower part of the rotor so as to protrude in the axial direction, while the upper part of the valve body is in contact with the projection, and the entire flow path in which the valve element contacts the valve seat In an electronic expansion valve provided with a stopper for restricting rotation of a rotor at a closing point, an electrode is provided at a contact portion between the stopper and the projection, and driving of the pulse motor is stopped by detecting conduction between the two electrodes. The electronic expansion valve is configured as described above.

Further, the stopper is formed of an insulating material, and an electrode connected to one of the external connection terminals is provided at the contact portion.

Further, the stopper is formed of a conductive material and is fixed to the valve body via an insulating material, and the insulating material is provided with one external connection terminal connected to the stopper.

The valve body, the bearing, the rotor and the projection are formed of a conductive material, and the valve body is provided with the other external connection terminal electrically connected to the electrode of the projection.

[0014] Further, the control section is provided with a stopper and a detection section for detecting conduction between the projections. When the conduction is detected, the electronic expansion valve is controlled by the control section to stop the pulse current flowing through the coil.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The electronic expansion valve of the present invention having the above-described structure is provided with electrodes at the abutment portions of the stopper provided at the upper portion of the valve body and the projection provided at the lower portion of the rotor, and the conduction between the two electrodes is provided. Is detected, the drive of the pulse motor is stopped, so regardless of the position of the valve body before the initialization control, the rotation drive of the rotor is stopped when the flow path is completely closed, so that the protrusion is formed. There is no repeated collision with the stopper.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an electronic expansion valve according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a partial exploded perspective view showing a conventional and an electronic expansion valve according to the present invention, FIG. 2 is a side sectional view showing a main part of an embodiment of an electronic expansion valve according to the present invention, and FIG. . FIG. 1 has been described in the section of the related art, and thus the description thereof is omitted. In FIGS. 2 and 3, the same functions as those in FIGS. 1 and 6 use the same reference numerals and have been described in the section of the related art, so that the description will be omitted.

In the present invention, for example, as shown in FIG. 2 and FIG. 3- (A), the stopper 5 is formed of a conductive material so that the tip is an electrode 5a, The valve body 1 is covered with an insulating material 5b such as a ceramic, and is buried.
Is provided. Further, the valve body 1, the fixed bearing 1g, the rotor 3b, and the projection 4 are formed of a conductor such as metal, and the outer periphery of the valve body 1 is formed with a recess 1f of the valve body 1 in which the case 6 is hermetically covered. The other external connection terminal 9b electrically connected to the electrode 4a of the protrusion 4 provided on the rotor 3b is fixed to the lower end with the screw 2.

FIG. 3B shows another embodiment. As shown in FIG. 3, the stopper 5 is formed of an insulating material such as a resin and communicates from the upper portion of the valve body 1 to the side surface. A metal electrode 5a is fixed to the top end, and one external connection terminal 9a is fixed to the side surface with screws 2, and the electrode 5a and the one external connection terminal 9a are connected by an electric wire 5c passing through the inside of the stopper 5. You may connect and form.

FIG. 4 is a schematic block diagram showing a control section of the electronic expansion valve according to the present invention. As shown in FIG.
Reference numeral 0 denotes a conduction detection unit 12 for detecting conduction between the electrode 4a of the protrusion 4 protruding from the rotor 3b of the pulse motor 3 and the electrode 5a of the stopper 5, and usually the operation of the indoor unit 20, the various units of the outdoor unit, and The control unit 11 controls the output of the pulse current to the pulse motor 3. At the time of initialization control, the control unit 11 controls the supply of the pulse current to the pulse motor 3 when the conduction detection unit 12 detects conduction between the electrodes 4a and 5a.

The operation of the above configuration will now be described. FIG. 5 is a schematic flowchart showing the operation of the initialization control. As shown in the figure, first, when the initialization control is started, the control unit 11
A pulse current is supplied to the coil 3a (ST1). Next, the conduction detecting unit 12 detects conduction between the electrode 4a and the electrode 5a (ST2). When the conduction is detected, the supply of the pulse current to the coil 3a is stopped (ST3), and the initialization control is completed.

[0021]

As described above, according to the electronic expansion valve of the present invention, the electrodes are provided at the contact portions of the stopper provided at the upper part of the valve body and the projection provided at the lower part of the rotor, and the conduction between the two electrodes is detected. Since the drive of the pulse motor is stopped, regardless of the position of the valve body before the initialization control, when the flow path is fully closed, the rotation drive of the rotor is stopped, and the protrusion repeatedly collides with the stopper. Therefore, it is possible to prevent the collision sound during the initialization control from being continued, prevent the life from being shortened, and improve the reliability by using an inexpensive method without increasing the external dimensions.

[Brief description of the drawings]

FIG. 1 is a partially exploded perspective view showing an electronic expansion valve according to the related art and the present invention.

FIG. 2 is a side sectional view showing a main part of an embodiment of the electronic expansion valve according to the present invention.

3A and 3B are enlarged cross-sectional views of an essential part showing an embodiment of an electronic expansion valve according to the present invention, wherein FIG. 3A shows one embodiment and FIG.

FIG. 4 is a schematic block diagram showing a control unit of the electronic expansion valve according to the present invention.

FIG. 5 is a schematic flowchart showing the operation of the initialization control of the electronic expansion valve according to the present invention.

FIG. 6 is a side sectional view showing a main part of a conventional electronic expansion valve.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 valve body 1a first passage 1b second passage 1c flow passage 1d valve seat 1e valve body 1e1 valve portion 1e2 step portion 1f concave portion 1g fixed bearing 2 screw 3 pulse motor 3a coil 3b rotor 3b1 circular shaft hole 3b2 concave portion 3b3 3c permanent magnet 4 protrusion 4a electrode 5 stopper 5a electrode 5b insulating material 5c electric wire 6 case 7 washer 8 coil spring 9a one external connection terminal 9b the other external connection terminal 10 control unit 11 control unit 12 conduction detection unit 20 indoor unit

Claims (5)

[Claims] 1. A valve seat provided in a flow passage communicating between a first passage and a second passage provided in a valve body, and a valve body for opening and closing the flow passage by coming into contact with and separating from the valve seat, The valve element converts the rotational motion of the rotor of the pulse motor, which is rotationally driven by passing a pulse current from the control unit to the coil, into a linear motion in the axial direction, and is driven by the linear motion. A protrusion is provided at the lower portion to protrude in the axial direction, while a stopper is provided at the upper portion of the valve body to limit the rotation of the rotor at the fully closed point of the flow path where the valve body contacts the valve seat. An electronic expansion valve, comprising: an electrode provided at a contact portion between the stopper and the projection; and detecting conduction between the two electrodes to stop driving the pulse motor. 2. The electronic expansion valve according to claim 1, wherein the stopper is formed of an insulating material, and an electrode connected to one of the external connection terminals is provided at the contact portion. 3. The valve according to claim 1, wherein the stopper is formed of a conductive material and fixed to the valve body via an insulating material, and the insulating material is provided with one external connection terminal connected to the stopper. The electronic expansion valve according to claim 1, wherein 4. The valve body, a bearing, a rotor and a projection are formed of a conductive material, and the valve body is provided with another external connection terminal electrically connected to an electrode of the projection. Item 7. The electronic expansion valve according to Item 1. 5. A control unit comprising a stopper and a detection unit for detecting conduction between protrusions, and upon detecting conduction, the control unit controls to stop a pulse current flowing through the coil. 2. The electronic expansion valve according to 1.