JP2000266194A - Two-stage type electric expansion valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To carry out a highly accurate flow rate control by the two-stage operation, unnecessarily to assemble a sealing means such as a packing to a movable part, without generating a leaking flow rate, and by making the structure simple. SOLUTION: In a main valve chamber 5 positioning at the upstream side from a main valve port 7, a main valve body 12 seating selectively to a valve seat 6, and to open and close the main valve port 7 is provided. At the back surface side of the main valve body 12, an auxiliary valve chamber 16 communicating constantly with the main valve chamber 5 is partitioned, an auxiliary valve port 19 to communicate the auxiliary valve chamber 16 to an outlet port 8 is provided, the auxiliary valve port 19 is made to open and close by a valve rod from of auxiliary valve body 20 connected movable only a specific amount in the valve lifting direction to the main valve body 12, the rotation of the rotor 29 of a stepping motor 25 is converted to the movement in the valve lifting direction of the main valve body 12 by spring type of rotation-linear movement converting means 31 and 32, and the auxiliary valve body 20 is moved in the valve lifting direction of the main valve body 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a two-stage electric expansion valve, and more particularly to a two-stage electric expansion valve capable of controlling a flow rate in a refrigerant circuit of a refrigerator.

[0002]

2. Description of the Related Art As a prior art of a two-stage electric expansion valve, there is one disclosed in Japanese Patent Publication No. 6-65515.

This electric expansion valve has an inlet port, a main valve chamber,
A valve housing having a valve seat portion, a main valve port, and an outlet port, and disposed in the main valve chamber located upstream of the main valve port, and selectively seating on the valve seat portion to form the main valve port. A piston-shaped main valve body that opens and closes, defines a back pressure chamber on the back side, and has a sub-valve port (passage) communicating the inlet port and the outlet port; and a valve lift relative to the main valve body A valve rod-shaped sub-valve that opens and closes the sub-valve port by moving in the valve lift direction with respect to the main valve body, and a motor attached to the valve housing; A rotation mechanism provided between the rotor and the sub-valve to convert the rotation of the rotor into movement of the main valve in the valve lift direction and move the sub-valve in the valve lift direction of the main valve; Linear movement conversion means, As it performed low flow rate control from the opening and closing of the auxiliary valve port by the sub-valve body is adapted to control the flow rate of the high flow rate from the opening and closing of the main valve port by the main valve body as the second stage.

In the above-described electric expansion valve, a pressure equalizing passage is formed in the main valve body so that the back pressure chamber communicates with the outlet port downstream of the main valve port to guide the pressure on the outlet port side to the back pressure chamber. The opening and closing of the main valve body can be performed with a low torque even in a large-capacity high-pressure circuit by uniformly applying the pressure on the outlet port side to the end surface of the back pressure chamber of the main valve body and the end surface of the main valve port side. In this way, the size of the motor is reduced.

[0005]

The conventional two-stage electric expansion valve as described above is satisfactory in that the main valve can be opened and closed with low torque even in a large-capacity high-pressure circuit. However, since the downstream pressure is always introduced into the back pressure chamber by the normally open pressure equalizing path, the upstream pressure leaks downstream through the back pressure chamber and the pressure equalizing path. In other words, in order to maintain the airtightness of the back pressure chamber with respect to the upstream side and to eliminate valve leakage when fully closed, sealing means such as packing is incorporated in the movable part of the main valve body and the sub-valve body. Need arises.

For this reason, the structure becomes complicated, and the number of parts,
The number of assembling steps increases, and maintenance work such as packing replacement is also required.

[0007] By the way, assuming that the main valve body is opened only for defrosting and dehumidification when the differential pressure between the upstream side and the downstream side is small, the above-mentioned two-stage electric expansion valve is used. There is no need to provide such a pressure equalizing path, and accordingly, it is not necessary to provide packing or the like in the movable parts of the main valve body and the sub valve body.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and the main valve is opened only when the differential pressure between the upstream side and the downstream side is small. As a suitable two-stage electric expansion valve used in, there is no need to incorporate sealing means such as packing in the movable part, no leakage flow rate is generated, the structure is simplified, and high precision by two-stage operation It is an object of the present invention to provide a two-stage electric expansion valve for controlling a flow rate.

[0009]

In order to achieve the above object, a two-stage electric expansion valve according to the present invention has an inlet port and an outlet port, and a main valve connected to the inlet port. A valve housing having a chamber and a main valve port communicating the main valve chamber and the outlet port formed therein; and a valve housing disposed in the main valve chamber and slidably fitted in a cylinder hole of the valve housing. A piston-shaped main valve body that selectively seats on a valve seat of the main valve port by sliding with respect to the cylinder hole to open and close the main valve port; and the main valve body inside the cylinder hole. A sub-valve chamber defined at a portion opposite to the main valve port with respect to the main valve port and constantly communicating with the main valve chamber via a communication passage formed inside the cylinder hole; and And the main valve body is connected to the main valve port. In a closed state, a sub-valve port that communicates the sub-valve chamber with the outlet port without passing through the communication passage is connected to the main valve body so as to be movable by a predetermined amount in a valve lift direction, A valve stem-shaped sub-valve that opens and closes the sub-valve port by movement in the valve lift direction with respect to the valve body, a motor attached to the valve housing, and a motor provided between the rotor of the motor and the sub-valve, Rotation-linear movement conversion means for converting the rotation of the rotor into movement of the main valve body in the valve lift direction and moving the sub-valve in the valve lift direction of the main valve body. .

[0010] In the two-stage electric expansion valve according to the second aspect of the present invention, the main valve body has a columnar shape, a chamfered portion is formed on an outer peripheral surface, and the communication path is formed by the chamfered portion. Things.

According to a third aspect of the present invention, there is provided a two-stage electric expansion valve, wherein a communication hole is formed in the main valve body, and the communication passage is formed by the communication hole.

In the two-stage electric expansion valve according to the first aspect of the invention, when the two-stage electric expansion valve is fully closed, the main valve body is seated on the valve seat to close the main valve port, The sub-valve closes the sub-valve port. Under this condition, the upstream pressure enters the sub-valve through the communication passage, and the sub-valve interior pressure is equal to the main valve chamber pressure. Not caused by closing the port.

When the two-stage electric expansion valve is opened from the fully closed state, the rotation of the rotor of the motor is converted into the movement of the main valve body in the valve lift direction by the rotation-linear movement conversion means. Moves in the valve lift direction (valve opening direction) of the main valve body. First, the sub-valve port is opened, and proportional flow control of a relatively small flow rate is performed according to the opening degree of the sub-valve port. When the sub-valve moves further in the valve lift direction (valve opening direction) of the main valve body, the main valve body moves in the valve lift direction (valve opening direction) by the sub-valve.
And the main valve body is separated from the valve seat to open the main valve port. At this time, a relatively large flow rate is controlled in accordance with the opening degree of the main valve port.

[0014] In the two-stage electric expansion valve according to the second aspect of the present invention, the main valve chamber and the sub-valve chamber are always in contact with each other through a communication passage formed by a chamfer formed on the outer peripheral surface of the main valve body. The fluid (fluid pressure) on the inlet port side is constantly supplied to the sub valve chamber.

In the two-stage electric expansion valve according to the third aspect of the present invention, the main valve chamber and the sub-valve chamber are always in communication with each other through a communication passage formed by a communication hole formed in the main valve body. Fluid (fluid pressure) on the inlet port side is constantly supplied to the sub-valve chamber.

[0016]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

(First Embodiment) FIGS. 1 and 2 show a first embodiment of a two-stage electric expansion valve according to the present invention.

The two-stage electric expansion valve comprises a valve housing body 1
And a cap housing 2 caulked to the valve housing body 1. In the valve housing body 1, an inlet port 4, a main valve chamber 5, a valve seat 6, a main valve port 7, and an outlet port 8 are formed.

An inlet joint pipe 10 containing a strainer 9 is connected to the inlet port 4, and an outlet joint pipe 11 is connected to the outlet port 8.

The main valve chamber 5 is located upstream of the main valve port 7 (on the inlet port 4 side), and a piston-shaped main valve body 12 is disposed in the main valve chamber 5. The main valve body 12 selectively seats on the valve seat 6 to open and close the main valve port 7;
And a cylindrical piston portion 14.

The cap member 2 has a cylinder hole 15 defined therein, and the piston portion 14 of the main valve body 12 is slidably fitted in the cylinder hole 15. The main valve body 12 defines a sub-valve chamber 16 on the back side (upper side) in cooperation with the cap member 2.

A chamfered portion 17 is formed on the outer peripheral surface of the piston portion 14 of the main valve body 12 in a two-chamfered shape, and a gap 1 between the chamfered portion 17 and the inner peripheral surface of the cylinder hole 15 is formed.
The sub valve chamber 16 communicates with the main valve chamber 5 by 8. Thus, the pressure relationship between the main valve chamber 5 and the sub valve chamber 16 is always the same.

The main valve body 12 has an auxiliary valve port 19 formed therein. The sub-valve port 19 communicates on the one hand with the sub-valve chamber 16 via the main valve body chamber 12a, and on the other hand, with the outlet port 8 opening at the tip end face of the main valve body 12 and downstream from the main valve port 7. Communicating.

A valve-shaped auxiliary valve element 20 is engaged with the main valve element 12. The sub-valve element 20 has a stopper 22 formed by a thrust washer locked by a C-ring 21 near the distal end, and only the gap ΔL between the stopper 22 and the C-ring 23 locked by the main valve element 12 is different from the main valve element 12. The sub-valve port 19 is opened and closed by the distal end 24 of the sub-valve 20 by the movement of the main valve 12 in the valve lift direction.

A gap L exists between the end face of the main valve body 12 and the inner bottom surface of the cylinder hole 15, and this gap L is the maximum lift of the main valve body 12. The maximum lift amount of the sub-valve element 20 as a valve rod is the gap ΔL + L.

The valve housing 3 has a stepping motor 2
5 is attached. The stepping motor 25 is
Mount member 26 fixed to valve housing body 1, dome-shaped rotor case 2 fixed to mount member 26
7, a stator coil 28 fixed to the outside of the rotor case 27, and a cylindrical rotor 29 rotatably provided in the rotor case 27. The rotor 29 is rotated by an excitation method such as a 1-2 phase excitation method. Drive.

A permanent magnet 30 is attached to the rotor 29, and a cylindrical female screw member 31 is fixed inside the rotor 29. A hollow shaft-like male screw member 32 screw-engaged with the female screw member 31 is mounted on the cap member 2. Has been fixed. The female screw member 31 and the male screw member 32 form a rotation-linear movement conversion means, and the rotation of the rotor 29 is converted into the movement of the main valve body 12 in the valve lift direction by the screw engagement of the two, and together with the rotor 29, The female screw member 31 moves in the valve lift direction.

The sub-valve element 20 extends through the hollow portion of the cap member 2 and the externally threaded member 32 into the interior of the rotor 29. The extended end of the sub-valve element 20 is connected to the rotor 29 and the internal thread by a nut 33 and a connection fitting 34. It is connected to the member 31.

A compression coil spring 35 is provided between the sub-valve 20 and the connection fitting 34. Compression coil spring 3
5 urges the sub-valve 20 in the valve closing direction.
After the abutment with the main valve body 12, the valve body is bent by being driven to close, so that the auxiliary valve body 20 is elastically pressed against the main valve body 12 and the main valve body 12 is elastically pressed against the valve seat portion 6.

A pin 36 is integrally formed on the upper end of the rotor 29, and a fixed rod 37 is fixed in the rotor case 27 in a manner that it is suspended from the ceiling. Fixed rod 3
A spiral guide member 38 is attached to the outer periphery of 7, and a movable stopper member 39 is engaged with the spiral guide member 38. The movable stopper member 39 is kicked by the pin 36 by the rotation of the rotor 29, and the spiral guide member 38
The upper limit position (maximum valve opening position) is defined by spirally moving and being brought into contact with the stopper portion 40.

Next, the operation of the two-stage electric expansion valve having the above configuration will be described.

When fully closed as shown, the main valve body 12 is seated on the valve seat 6 with the valve portion 13 to close the main valve port 7, and the sub-valve body 20 comes into contact with the main valve body 12. The sub-valve 20 closes the sub-valve port 19. In this state, the pressure on the upstream side enters the sub-valve chamber 16 through the gap 18 formed by the chamfered portion 17 between the sub-valve chamber 16 and the inner peripheral surface of the cylinder hole 15, and the internal pressure of the sub-valve chamber 16 The pressure is equal to the internal pressure of the valve chamber 5, and a sufficient fully closed state is obtained by the valve shutoff characteristics of the main valve body 12 and the sub-valve element 20. It is not necessary to provide such as.

When the valve is opened from the fully closed state as described above, the rotor 29 of the stepping motor 25 is rotated in the direction opposite to the direction when the valve is closed. Rotation of the rotor 29 is performed by the screw engagement between the female screw member 31 and the male screw member 32, and
Is converted into a linear movement in the valve lift direction of the female screw member 31.
Is transmitted to As a result, the sub-valve 20 moves in the valve-opening direction with respect to the main valve 12 in a state of being lifted, and the sub-valve port 19 is opened. The opening degree of the sub-valve port 19 is determined by the rotation angle of the rotor 29, and the small-diameter sub-valve port 19 performs proportional flow control with a relatively small flow rate.

In this state, the main valve 1
2 keeps the valve closed, so that there is no other leakage flow rate, and the proportional flow rate control with a small flow rate is performed stably with high accuracy. If necessary, a spring for urging the main valve body 12 to close the valve can be provided between the main valve body 12 and the cap member 2.

Further, when the rotor 29 of the stepping motor 25 rotates in the direction opposite to the direction when the valve is closed and the sub-valve element 20 moves in the valve opening direction, the gap ΔL between the stopper 22 and the C ring 23 disappears. When the stopper 22 comes into contact with the C-ring 23, the main valve body 12 is moved in the valve opening direction by the auxiliary valve body 20. Thereby, the valve portion 13 of the main valve body 12 is separated from the valve seat portion 6, the large-diameter main valve port 7 is opened, and a large flow rate can be obtained.

The expansion valve action is obtained by controlling the opening of the sub-valve port 19 as described above. Open the main valve body 12 (fully open)
For example, it can be set so as to be a time for defrosting and dehumidifying at a low differential pressure when the operation of the compressor of the refrigeration cycle is stopped. This eliminates the need for a large motor torque to open the main valve body 12 in combination with the fact that the movable portion does not have sliding resistance due to packing or the like, and generates a large fluid flow noise when the main valve body 12 is opened. This is also avoided.

(Embodiment 2) FIG. 3 shows Embodiment 2 of a two-stage electric expansion valve according to the present invention. In FIG. 3, portions corresponding to those in FIG. 1 are denoted by the same reference numerals as those in FIG. 1, and description thereof will be omitted.

In this embodiment, a communication hole 41 is formed in the abdomen of the main valve body 12, and the auxiliary valve chamber 16 and the main valve body chamber 12 a communicate with the main valve chamber 5 through the communication hole 41. . Thus, the pressure relationship between the main valve chamber 5, the sub-valve chamber 16, and the main valve chamber 12a is always the same.

The structure of the second embodiment is substantially the same as that of the first embodiment except for the structure of the pressure passage (communication hole 41). Therefore, the second embodiment has the same structure as that of the first embodiment. Functions and effects can be obtained.

[0040]

As can be understood from the above description, according to the two-stage electric expansion valve according to the first aspect of the present invention, the main valve chamber having the inlet port and the outlet port and communicating with the inlet port is provided. A valve housing in which a main valve port communicating the main valve chamber and the outlet port is formed; and a valve housing disposed in the main valve chamber and slidably fitted in a cylinder hole of the valve housing; A piston-shaped main valve element that selectively seats on the valve seat of the main valve port to open and close the main valve port by sliding with respect to the cylinder hole, and sandwiches the main valve element inside the cylinder hole. A sub-valve chamber which is defined at a portion opposite to the main valve port and is always in communication with the main valve chamber via a communication passage formed inside the cylinder hole; And the main valve body closes the main valve port. State, and the sub-valve port communicating the auxiliary valve chamber without passing through the communication passage to said outlet port,
A valve rod-shaped sub-valve that is movably connected to the main valve in the valve lift direction by a predetermined amount, and opens and closes the sub-valve port by movement in the valve lift direction with respect to the main valve; An attached motor, provided between a rotor of the motor and the sub-valve, converting rotation of the rotor into movement of the main valve in a valve lift direction, and converting the sub-valve into the main valve; And a rotation-linear movement conversion means for moving in the valve lift direction.

Therefore, in the fully closed state of the two-stage electric expansion valve, the main valve body is seated on the valve seat to close the main valve port, and the sub-valve body closes the sub-valve port. Under this condition, a completely closed valve with no leakage is obtained. When the two-stage electric expansion valve is opened from the fully closed state, the rotation of the motor rotor is converted into the movement of the main valve body in the valve lift direction by the rotation-linear movement conversion means, and the sub-valve element is opened. The sub-valve port is opened first, and the proportional flow rate control with a relatively small flow rate according to the opening degree of the sub-valve port is performed with high accuracy without causing a leak flow rate elsewhere.

Further, when the sub-valve moves in the valve opening direction, the main valve moves in the valve opening direction by the sub-valve, and the main valve separates from the valve seat to open the main valve port. Flow control of a target flow rate is performed. The main valve body can be set to open, for example, at the time of low differential pressure such that the operation of the compressor of the refrigeration cycle is stopped, for defrost or dehumidification. In addition, since there is no sliding resistance due to packing or the like in the movable part, a large motor torque is not required to open the main valve body, and a large fluid flow noise is generated when the main valve body is opened. Be avoided.

According to the two-stage electric expansion valve according to the second aspect of the present invention, the main valve body has a cylindrical shape, a chamfered portion is formed on the outer peripheral surface, and the communication passage is constituted by the chamfered portion. It was assumed.

For this reason, the main valve chamber and the sub-valve chamber communicate with each other through a communication passage formed by a chamfered portion formed on the outer peripheral surface of the main valve body. , The fluid (fluid pressure) on the inlet port side is always supplied.

In the two-stage electric expansion valve according to the third aspect of the present invention, a communication hole is formed in the main valve body, and the communication passage is formed by the communication hole.

For this reason, the main valve chamber and the sub-valve chamber communicate with each other through a communication passage formed by a communication hole formed in the main valve body, and the inlet port is connected to the sub-valve chamber without complicating the structure. Side fluid (fluid pressure) is always supplied.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a two-stage electric expansion valve according to the present invention.

FIG. 2 is a perspective view showing a main valve body of the two-stage electric expansion valve according to the first embodiment of the present invention.

FIG. 3 is a sectional view showing Embodiment 2 of a two-stage electric expansion valve according to the present invention.

[Explanation of symbols]

 Reference Signs List 3 valve housing 4 inlet port 5 main valve chamber 6 valve seat 7 main valve port 8 outlet port 12 main valve body 16 sub valve chamber 17 chamfered section 19 sub valve port 20 sub valve body 21 C ring 22 stopper 23 C ring 25 stepping Motor 28 Stator coil 29 Rotor 31 Female screw member 32 Male screw member 41 Communication hole

Claims (3)

[Claims] A valve housing having an inlet port and an outlet port, and a main valve chamber communicating with the inlet port, and a main valve port communicating the main valve chamber with the outlet port formed therein; The main valve port is disposed in the main valve chamber and slidably fitted in a cylinder hole of the valve housing, and is selectively seated on a valve seat of the main valve port by sliding with respect to the cylinder hole to open and close the main valve port. A main valve body having a piston shape, and a communication passage defined inside the cylinder hole and opposite to the main valve port with the main valve body interposed therebetween, and formed inside the cylinder hole. A sub-valve chamber that is always in communication with the main valve chamber through the main valve port, wherein the main valve body closes the main valve port without passing through the communication passage. A sub-valve port communicating the sub-valve to the outlet port; A valve rod-shaped sub-valve that is movably connected to the main valve body in a valve lift direction by a predetermined amount, and that opens and closes the sub-valve port by movement in the valve lift direction with respect to the main valve body; An attached motor, which is provided between a rotor of the motor and the sub-valve, converts rotation of the rotor into movement of the main valve in a valve lift direction, and converts the sub-valve into the main valve. A two-stage electric expansion valve, comprising: a rotation-linear movement conversion means for moving in a valve lift direction. 2. The two-stage type according to claim 1, wherein the main valve body has a cylindrical shape, a chamfered portion is formed on an outer peripheral surface, and the chamfered portion forms the communication passage. Electric expansion valve. 3. The two-stage electric expansion valve according to claim 1, wherein a communication hole is formed in the main valve element, and the communication path is formed by the communication hole.