JP2000352472A - Motor-driven expansion valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size of a motor and reduce the cost by restraining an opening of a valve port by rotation of a valve element. SOLUTION: A cap-like spring receiver 10 functions as a spring receiver of a compression coil spring 11 and is fixed to the root part of a shaft. A stopper piece 10a is formed on the outer peripheral edge part of the cap-like spring receiver 10, whereby when a valve shaft is rotated, the stopper piece 10a is made abut on a rotation constraint pin 5 to constitute a stopper mechanism. A valve body 12 is provided with a non-circular shaft hole 12a formed in the central part corresponding to the cut face 4a of an output shaft 4. A valve element 12b is formed like a cam plate on the lower surface to control the opening of a valve port 8. When the valve body 12 is fitted in the output shaft 4, the cam plate-like valve element 12b is pressed to a valve seat 9 so that the valve element 12b slides the output shaft 4 to draw a circular locus in the center.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric expansion valve used as an electronically controlled expansion valve used in a refrigerating cycle of a room air conditioner or a car air conditioner, or a proportional control valve used in combination with a microcomputer in general industrial fields. Regarding the valve, the electric resolution is improved by making the stepping motor a motor with a speed reduction mechanism, and the shape of the valve body driven by the output shaft of this speed reducer is such that the opening of the valve port is controlled. This is an electric expansion valve.

Conventionally, various types of electric expansion valves which are controlled by a microcomputer by combining a stepping motor and a valve have been devised. FIG. 5 shows a structure of a conventional electric expansion valve disclosed in Japanese Utility Model Publication No. 3-36770 (hereinafter, referred to as a direct-acting needle valve stepping motor system for convenience), and the configuration thereof will be described below. The conventional electric expansion valve of the direct-acting needle valve stepping motor type is a motor-driven expansion valve formed integrally with the valve shaft 3 by energizing a stator coil 2 fixed to an outer peripheral portion of a cylindrical case 21 made of a non-magnetic material. The rotor 24 is rotated, and the rotation is converted into a linear motion of the valve shaft 23 by a male screw 25 formed on the valve shaft 23 and a female screw 27 of a propulsion bearing 26 screwed thereto. The opening degree of the valve is controlled by a needle valve 28 formed at the tip.

A valve body 29 is provided at the lower end of the case 21. The valve body 29 has a first passage 30 and a second passage 31, and is provided between the two passages. An orifice 32 and a valve seat 33 are provided, and a chamber 34 is provided at the center of the valve body 29. The propulsion bearing 26 is provided in the chamber 34.
Is press-fitted and fixed.

A rotor sleeve 35 formed integrally with the rotor 24 has a convex portion 36 (a plate-like stopper piece) protruding radially at one location on the inner peripheral surface thereof.
Is provided.

A lid 37 is provided at the upper end of the case 21. The inner surface of the lid 37 is spaced apart from the center to a position where the stop pin 38 reaches the middle of the projection 36. Hanged and fixed.

The stop pin 38 and the side surface of the projection 36 are brought into contact with each other in a range of less than one rotation of the rotor 24 of the motor.
8 is regulated.

[0007]

By the way, the above-mentioned conventional direct-acting needle valve stepping motor has a valve shaft 23.
Since the needle valve 28 is controlled by a rotation of less than one rotation, only an electrical resolution of at most several tens of pulses can be obtained. For example, if the rotor is a permanent magnet magnetized to 12 poles, even if the energization control to the coil is performed in 1-2 phase excitation and the resolution is increased, the rotation is 1 rotation / 48 pulses. At most, a resolution of only about 40 pulses was obtained. In addition, since the needle valve system requires precision, it is necessary to form a male screw and a female screw of the propulsion unit which increase the cost.

On the other hand, in the case of a room air conditioner or the like, the use of an inverter for a compressor has been advanced, and the direction of cooling and heating with a lower input has been pursued in detail in accordance with the rotation of the compressor and fluctuations of the cooling and heating load. It is necessary to finely control the opening degree, that is, to increase the resolution. The resolution is set to several hundred pulses, for example, about 500 pulses.

As a specific means, a method of obtaining an electrical resolution of about 500 pulses by rotating the rotor 10 times when using the rotor is used. As another means to enhance the electrolysis, there is a method of increasing the resolution by duty controlling the coil energization while the rotor moves between the poles, such as "micro step drive", and increasing the focal length of the camera. Although it is practically used for adjustment and the like, it is always energized, so it is not suitable for control like a room air conditioner, contrary to energy saving.

Further, in the conventional structure, since the needle valve is directly driven to rotate by the rotation shaft of the stepping motor, a propulsive force is required, and there is a problem that the motor portion becomes large accordingly. In addition, the cost of the male screw and the propulsion bearing was high.

[0011]

SUMMARY OF THE INVENTION The present invention uses a stepping motor with a speed reducer as a drive unit of an electric expansion valve to improve the electrical resolution and reduce the size of the motor unit. A valve body controlled only by rotation is provided on the lower surface of the valve body driven by the valve body, and the opening degree of the valve port is controlled by less than one rotation of the valve body to improve the geometric resolution. By sliding on the seat, no frictional resistance is generated on the seating surface as in the related art. As an effect thereof, it is an object to provide a small and inexpensive control valve by realizing the downsizing of the motor unit while simplifying the stopper mechanism unit while keeping the electrical and geometrical resolution high.

That is, the electric expansion valve according to claim 1 is
A first passage 2 is provided on the lower side of a cylindrical sealed case 1 having an upper and lower opening, and a stator coil is arranged in the sealed case 1 on the inner periphery of a motor case. A stepping motor 3 with a speed reduction mechanism is provided, an output shaft 4 of the stepping motor 3 is provided with a cut surface 4a, a lid 6 is provided at an upper end of the closed case 1, and a lower end of the closed case 1 is provided at a lower end of the closed case 1. Is provided with a disc-shaped valve seat sheet 9 having a valve port 8 communicating with the second passage 7, and a cap-shaped spring receiver 10 is fixedly provided at the base of the output shaft 4,
A non-circular shaft hole 12a corresponding to the cut surface 4a is formed on the output shaft 4 via a compression coil spring 11, and a valve port for controlling the opening of the valve port 8 is entirely covered on the lower surface. The valve body 12 formed by changing the shape of the valve body 12b from a sufficient radius to a radius sufficient to fully open the valve port into a cam plate shape is provided by being fitted thereinto. The opening degree of the valve port 8 is controlled in less than one rotation.

Further, in the electric expansion valve according to a second aspect of the present invention, the shape of the valve body 12b for controlling the opening of the valve port is a disk shape,
An arc-shaped groove 13 whose one end communicates with the outer peripheral portion of the valve body with the radius being the distance between the center of the valve body 12b and the valve port is cut, and from a position where the groove 13 does not cover the valve port (8). 2. The method according to claim 1, wherein the position is changed to a position having a maximum width and depth larger than the valve port.

Further, in the electric expansion valve according to the third aspect, a rotation restraining pin 5 is provided at the bottom of the motor case of the stepping motor 3 so as to be spaced apart from the axis of the output shaft 4 in a drooping manner. The stopper piece (10a) is provided on the outer peripheral edge of the spring receiver (10).

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a longitudinal sectional side view of the electric expansion valve of the present invention, and FIG. 2 is a sectional view taken along line AA of FIG. The electric expansion valve according to the present invention comprises a cylindrical closed case 1, a stepping motor 3 with a deceleration, a lid 6, a disc-shaped valve seat sheet 9, a cap-shaped spring receiver 10, a compression coil spring 11, a valve body. 12.

The stepping motor 3 with the speed reduction mechanism has a non-circular output shaft at the lower end, and in this embodiment, is provided with a cut surface 4a. Further, since the stepping motor is provided with a speed reduction mechanism, the rotation of the output shaft 4 has a resolution of 500 pulse class in one rotation. Also,
At the bottom of the motor case and at a position away from the axis of the output shaft 4, a rotation restraining pin 5 is provided in a hanging manner.
The output shaft at the lower end of the stepping motor 3 with the speed reduction mechanism has a non-circular shape.

The cylindrical hermetically closed case 1 is a cylindrical body having upper and lower openings, and a first side is provided on the lower side of the case.
Is provided. The stepping motor 3 with the speed reduction mechanism is fixed in the closed case 1 by an appropriate means. Thereafter, the opening above the closed case 1 is closed by the lid 6. Reference numeral 3a denotes a hermetic terminal from which a lead wire of the motor is taken out and hermetic sealing is performed on the lead wire.

The disc-shaped valve seat 9 is fixed to an opening at the lower end of the case.
A valve port 8 communicating with the second passage 7 at a position away from the center
Is provided.

The cap-shaped spring support 10 serves as a spring support for a compression coil spring 11 described later.
The cap-shaped spring receiver 10 is fixed to the root of the shaft. If necessary, a cap-shaped spring receiver 10 may be used.
By forming the stopper piece 10a on the outer peripheral edge of the stopper member, when the valve shaft rotates, the stopper piece 10a comes into contact with the rotation restraining pin 5 to form a stopper mechanism.

The valve body 12 has the output shaft 4 at its center.
A non-circular shaft hole 12a corresponding to the cut surface 4a is formed, and a valve body 12b is formed on the lower surface in a cam plate shape to control the opening of the valve port 8. (See FIG. 2.) When the valve body 11 is fitted into the output shaft 4, the cam plate-shaped valve body 12 b is pressed against the valve seat 9, and the valve body 12 b is moved around the output shaft 4. It slides along an arc-shaped trajectory. In addition, the said valve main body can be shape | molded by resin molding, for example.

FIG. 3 is a longitudinal sectional side view of an electric expansion valve showing another embodiment of the present invention, and FIG. 4 is a sectional view taken along line BB of FIG. The motor-operated expansion valve in this embodiment includes a valve body 12.
Except for the shape of the valve body formed in FIG.
Since it is completely the same as the electrically operated expansion valve described above, detailed description of the same components will be omitted.

In the electric expansion valve shown in FIG. 3, the valve element 12b
Is shaped like a disc, and the disc-shaped valve element 12b
As shown in FIG. 4, an arc-shaped groove 13 is provided on the lower surface thereof, with the radius being the distance between the center of the valve body 12b and the valve port, and having one end communicating with the outer peripheral portion of the valve body. The flow path 14 changes from a position not covering the valve port 8 to a maximum width larger than the valve port 9.

[0023]

As described above, the motor used in the electric expansion valve of the present invention is a gear motor that improves the electrical resolution and the torque of the motor. Therefore, the motor can be reduced in size and cost can be reduced. Can be. Further, since the valve element slides on the valve seat, there is no frictional resistance at the seating surface unlike the related art, and the reverse operation after closing the valve, that is, opening of the valve can be easily performed without using the rotation stopper. . Further, by forming the valve body by resin molding and controlling the opening degree of the valve port, the need for external threads, bearing internal threads and needles is eliminated, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an electric expansion valve of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a longitudinal sectional view of an electric expansion valve showing another embodiment of the present invention.

FIG. 4 is a sectional view taken along line BB of FIG. 3;

FIG. 5 is a longitudinal sectional view of a conventional electric expansion valve.

[Explanation of symbols]

1 closed case, 2 first passage, 3
Stepping motor, 4 output shafts, 4a
Cut surface 5 rotation restraint pin, 6 lid,
7 second passage, 8 valve port, 9 valve seat, 10 cap-shaped spring receiver, 10a stopper piece, 11 compression coil spring, 12 valve body, 12a non-circular shaft hole, 12b valve body,
13 grooves.

Claims (3)

[Claims] 1. A cylindrical closed case having upper and lower openings.
A first passage (2) is provided on the lower side of (1), and a stepping motor with a speed reduction mechanism in which a stator coil is disposed in the inner periphery of the motor case is provided in the closed case (1). motor
(3), a cut surface (4a) is provided on the output shaft (4) of the stepping motor (3), and a lid (6) is provided on the upper end of the closed case (1). At the lower end of (1), a disc-shaped valve seat (9) provided with a valve port (8) communicating with the second passage (7) is provided, and at the base of the output shaft (4). Is a cap-shaped spring support (10)
A non-circular shaft hole (1) corresponding to the cut surface (4a) is provided on the output shaft (4) via a compression coil spring (11).
2a) and a valve element having a lower surface that is varied from a radius sufficient to entirely cover the valve port for controlling the opening of the valve port (8) to a radius sufficient to fully open the valve port (8). 12
A valve body (12) having a shape of b) formed in a cam plate shape is provided so as to be fitted therein, and the opening degree of the valve port (8) is controlled by less than one rotation of the output shaft (4). An electric expansion valve characterized by the following. 2. A valve body (12b) for controlling an opening of said valve port.
Is formed in a disc shape, and an arc-shaped groove (13) having a radius equal to the distance between the center of the valve element (12b) and the valve port and having one end communicating with the outer peripheral part of the valve element is cut. 3. The electric expansion valve according to claim 1, wherein the position of the valve is changed from a position not covering the valve port to a position having a maximum width and depth larger than the valve port. 3. A rotation restraining pin (5) is provided at the bottom of the motor case of the stepping motor (3) in a manner spaced apart from the axis of the output shaft (4), and a cap-shaped spring receiver (1) is provided.
The electric expansion valve according to claim 1 or 2, wherein a stopper piece (10a) is provided at an outer peripheral edge of (0).