JP2021152381A - Flow passage switching valve - Google Patents

Abstract

To provide a flow passage switching valve that has a simple structure, is easy to assemble, and can accurately control a flow rate of fluid.SOLUTION: A flow passage switching valve comprises: a valve body comprising a valve chest, a first connecting part for connecting a first pipe and the valve chest, a second connecting part for connecting a second pipe and the valve chest, a third connecting part for connecting a third pipe and the valve chest, a first valve port provided between the first connecting part and the second connecting part, and a second valve port provided between the second connecting part and the third connecting part; and a valve stem arranged movably in the valve chest, and inserted into the first valve port and the second valve port. The valve stem comprises a first valve element part for controlling a passage flow rate of fluid flowing through the first valve port, and a second valve element part for controlling a passage flow rate of the fluid flowing through the second valve port. The first valve element part and the second valve element part each comprises a taper part and a cylindrical part. A maximum outside diameter of the second valve element part is smaller than inside diameters of the first valve port and the second valve port.SELECTED DRAWING: Figure 3

Description

The present invention relates to a flow path switching valve.

Conventionally, the fluid that has been connected to the first inflow port, the second inflow port, and the third inflow port and has flowed in from the first inflow port is distributed and supplied to the second inflow port or the third inflow port. Various flow path switching valves have been proposed.

For example, the flow path switching valve disclosed in Patent Document 1 includes a valve chamber, an upper valve seat, and a valve body having a lower valve seat that communicate with a first inlet / outlet, a second inlet / outlet, and a third inlet / outlet. It has a valve shaft that moves within the valve body. According to such a flow path switching valve, the fluid flowing in from the first inflow port can be supplied to the second inflow port or the third inflow port according to the moving position of the valve shaft.

JP-A-2017-129240

By the way, in the above-mentioned flow path switching valve, the upper valve body and the lower valve body provided on the valve shaft are selectively seated or separated from the upper valve seat and the lower valve seat of the valve body, so that the fluid is fluid. The flow direction is switched. Here, the upper valve seat and the lower valve seat are formed at both ends of the hollow valve seat member, and the upper valve body and the lower valve body are connected by a connecting shaft inserted inside the valve seat member. Therefore, when assembling the flow path switching valve, the upper valve body and the lower valve body must be assembled from both sides in the axial direction with the valve seat member sandwiched between them, which causes a problem that it takes time to assemble. Further, there is also a problem that the amount of fluid flowing to the second inflow port or the third inflow port tends to fluctuate due to an assembly error or a positioning error during operation.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a flow path switching valve capable of accurately controlling the flow rate of a fluid while having a simple structure and easy assembly.

The flow path switching valve according to the present invention is
A valve chamber, a first connecting portion connecting the first pipe and the valve chamber, a second connecting portion connecting the second pipe and the valve chamber, and a third connecting portion connecting the third pipe and the valve chamber. It has a first valve port provided between the first connection portion and the second connection portion, and a second valve port provided between the second connection portion and the third connection portion. With the valve body
A valve shaft movably arranged in the valve chamber and inserted into the first valve port and the second valve port,
Have,
The valve shaft has a first valve body portion that controls the passing flow rate of the fluid flowing through the first valve port, and a second valve body portion that controls the passing flow rate of the fluid flowing through the second valve port.
The first valve body portion and the second valve body portion are provided with a tapered portion and a cylindrical portion, respectively.
The maximum outer diameter of the second valve body portion is smaller than the inner diameters of the first valve port and the second valve port.

According to the flow path switching valve of the present invention, the flow rate of the fluid can be controlled with high accuracy while being easy to assemble with a simple structure.

FIG. 1 is a vertical cross-sectional view showing a flow path switching valve of the present embodiment. FIG. 2 is a diagram showing the flow path characteristics of the flow path switching valve of the present embodiment, in which the vertical axis represents the flow rate ratio and the horizontal axis represents the valve shaft lift amount. FIG. 3 is an enlarged cross-sectional view showing the periphery of the valve body portion of the flow path switching valve in an enlarged manner. FIG. 4 is an enlarged cross-sectional view showing the periphery of the valve body portion of the flow path switching valve in an enlarged manner. FIG. 5 is an enlarged cross-sectional view showing the periphery of the valve body portion of the flow path switching valve in an enlarged manner. FIG. 6 is an enlarged cross-sectional view showing the periphery of the valve body portion of the flow path switching valve in an enlarged manner. FIG. 7 is an enlarged cross-sectional view showing the periphery of the valve body portion of the flow path switching valve in an enlarged manner. FIG. 8 is an enlarged cross-sectional view showing the periphery of the valve body portion of the flow path switching valve in an enlarged manner. FIG. 9 is a cross-sectional view similar to FIG. 3 showing the periphery of the valve body portion in the comparative example. FIG. 10 is an enlarged view of the vicinity of the first valve body portion of the valve shaft according to the modified example of the present embodiment as a side view. FIG. 11 is a diagram showing the flow path characteristics of the flow path switching valve of this modified example.

Hereinafter, embodiments of the flow path switching valve according to the present invention will be described with reference to the drawings. In the present specification, the direction from the rotor to the valve chamber is downward, and the opposite direction is upward, but the installation direction of the flow path switching valve is not limited to this. Further, the refrigerant used for the refrigeration cycle is used as the fluid of the following embodiments.

FIG. 1 is a vertical cross-sectional view showing the flow path switching valve 10 of the present embodiment. The flow path switching valve 10 includes a valve main body 20, a can 40 having a rotor 30 attached to the valve main body 20 to drive the valve shaft 24, and a stator 50 externally fitted in the can 40 to drive the rotor 30 to rotate. I have. Let L be the axis of the flow path switching valve 10.

A pair of bobbins 52, a stator coil 53, and a yoke 51 surrounding them are arranged on the outer circumference of the cylindrical portion of the can 40, and the stator 50 is formed by covering the outer circumference with a resin mold cover 56. The rotor 30 and the stator 50 form a stepping motor (driving unit).

The can 40 is made of a non-magnetic metal such as stainless steel and has a bottomed cylindrical shape. The open lower end of the can 40 is fixed to a stainless steel annular plate 41 by welding or the like.

The substantially cylindrical valve shaft 24 is movably arranged in the valve chamber VC, is made of stainless steel, brass, or the like, and has a small diameter shaft portion 241 on the upper end side, a large diameter shaft portion 242, and a valve body structure portion on the lower end side. It is connected to 243 coaxially. The configuration of the valve body structure portion 243 will be described later with reference to FIG.

The substantially cylindrical valve shaft holder 32 is arranged in the can 40 so as to accommodate the upper end side of the valve shaft 24. The upper end of the valve shaft holder 32 is joined by a push nut 33 in which the upper end of the small diameter shaft portion 241 of the valve shaft 24 is press-fitted and fixed.

A return spring 35 composed of a compression coil spring is attached along the outer circumference of the push nut 33. When the fixing screw portion 25 of the guide bush 26 and the moving screw portion 31 of the valve shaft holder 32 are unscrewed, the return spring 35 comes into contact with the inner surface of the top of the can 40 and the fixing screw portion 25 It has a function of urging the screw with the moving screw portion 31 so as to restore the screwing.

The rotor 30 arranged with a gap with respect to the can 40 and the valve shaft holder 32 are connected via a support ring 36. More specifically, the support ring 36 is composed of a metal ring made of copper inserted at the time of molding the rotor 30, and the upper protrusion of the valve shaft holder 32 is fitted into the inner peripheral hole of the support ring 36, and the upper protrusion is formed. The outer circumference of the portion is caulked and fixed to connect the rotor 30, the support ring 36, and the valve shaft holder 32.

An upper stopper body 37 constituting one of the stopper mechanisms is fixed to the outer circumference of the valve shaft holder 32. The upper stopper body 37 is made of a tubular resin, and a plate-shaped upper stopper piece 37a is projected downward.

A cylindrical guide bush 26 is arranged between the valve shaft holder 32 and the valve shaft 24. The lower end of the guide bush 26 is press-fitted into the upper end opening 201 of the valve body 20 by press fitting. A lower stopper body 27 constituting the other side of the stopper mechanism is fixed to the outer periphery of the guide bush 26. The lower stopper body 27 is made of a ring-shaped resin, and a plate-shaped lower stopper piece 27a is projected above, and can be engaged with the upper stopper piece 37a described above.

The lower stopper body 27 is fixed to the spiral groove portion 26a formed on the outer periphery of the guide bush 26 by injection molding, and the upper stopper body 37 is fixed to the spiral groove portion 32b formed on the outer periphery of the valve shaft holder 32 by injection molding. ing.

A moving screw portion 31 is formed on the inner surface of the valve shaft holder 32, and is screwed with a fixing screw portion 25 formed on the outer periphery of the guide bush 26.

The valve shaft 24 is fitted into the valve shaft holder 32 so as to be vertically movable along the axis L, and is urged downward by a compression coil spring 34 compressed in the valve shaft holder 32. A pressure equalizing hole 32a for balancing the pressure in the valve chamber VC and the can 40 is formed on the side surface of the guide bush 26.

The upper end of a substantially hollow cylindrical valve body 20 is fixed to the central opening of the annular plate 41 of the can 40 by brazing.

The bottomed cylindrical valve body 20 has an intermediate expansion hole 202 formed between the upper expansion hole 202 connected to the upper end opening 201, the lower expansion hole 203 on the lower end side, and the upper expansion hole 202 and the lower expansion hole 203. It has 204 and. The valve chamber VC is formed by the upper expansion hole 202, the lower expansion hole 203, and the intermediate expansion hole 204.

The upper expansion hole 202 and the intermediate expansion hole 204 communicate with each other via the first valve port 205, and the intermediate expansion hole 204 and the lower expansion hole 203 communicate with each other via the second valve port 206. The inner diameter of the first valve port 205 is slightly larger than the outer diameter of the large diameter shaft portion 242, and the inner diameter of the second valve port 206 is slightly larger than the outer diameter of the end shaft portion 247 described later. It is preferable that the first valve port 205 and the second valve port 206 have the same diameter. In the present embodiment, the first valve port 205 and the second valve port 206 are both cylindrical, but may be a conical pedestal surface or a cylindrical portion having a conical pedestal surface.

The valve body 20 includes an upper communication hole (first connection portion connecting the valve chamber VC and the first pipe T1) 207 formed so as to extend from the upper expansion hole 202 in a direction orthogonal to the axis L, and an upper portion. It is provided with an upper joint hole 208 having a diameter larger than that of the communication hole 207. The first pipe T1 is joined to the upper joint hole 208 by brazing or the like. Let the axis of the first pipe T1 be O1.

Further, the valve body 20 includes an intermediate communication hole (second connection portion connecting the valve chamber VC and the second pipe T2) 209 formed so as to extend from the intermediate expansion hole 204 in a direction orthogonal to the axis L. It is provided with an intermediate joint hole 210 having a diameter larger than that of the intermediate communication hole 209. The second pipe T2 is joined to the intermediate joint hole 210 by brazing or the like. The axis of the second pipe T2 is O2.

Further, the valve body 20 includes a lower communication hole (a third connection portion connecting the valve chamber VC and the third pipe T3) 211 formed so as to extend from the lower expansion hole 203 in a direction orthogonal to the axis L. It is provided with a lower joint hole 212 having a diameter larger than that of the lower communication hole 211. A third pipe T3 is joined to the lower joint hole 212 by brazing or the like. The axis of the third pipe T3 is O3. Here, the axes O1, O2, and O3 are provided on the same plane including the axis L, but they do not necessarily have to be provided on the same plane.

FIG. 2 is a diagram showing the flow path characteristics of the flow path switching valve 10 of the present embodiment, and FIGS. 3 to 8 are enlarged cross-sectional views showing the periphery of the valve body structure portion 243 of the flow path switching valve 10. Is.

As can be seen with reference to FIG. 3, the valve body structure portion 243 of the valve shaft 24 includes a first valve body portion 244, a cylindrical connecting shaft portion 246, a second valve body portion 245, and a cylindrical end shaft. It is connected to the part 247. The first valve body portion 244 and the second valve body portion 245 have a larger diameter than the connecting shaft portion 246, and in the present embodiment, they have the same shape even if they are turned upside down.

The first valve body portion 244 that controls the passing flow rate of the refrigerant flowing through the first valve port 205 includes a first large taper portion 244a connected to the large diameter shaft portion 242 and a first cylinder connected to the first large taper portion 244a. The portion 244b is composed of a first small tapered portion 244c connected to the first cylindrical portion 244b and the connecting shaft portion 246. The large-diameter shaft portion 242 and the connecting shaft portion 246 may also be a part of the first valve body portion 244 as a cylindrical portion.

The second valve body portion 245 that controls the passing flow rate of the refrigerant flowing through the second valve port 206 includes a second large taper portion 245a on the lower end side, a second cylindrical portion 245b connected to the second large taper portion 245a, and a second cylinder portion 245b. It is composed of a second small taper portion 245c connected to the two cylindrical portions 245b and the connecting shaft portion 246. The connecting shaft portion 246 and the end shaft portion 247 may also be a part of the second valve body portion 245 as a cylindrical portion. In addition, when referring to both the 1st large taper part and the 2nd large taper part in this specification, it is referred to as a large taper part. Similarly, when referring to both the first small taper portion and the second small taper portion, it is referred to as a small taper portion.

According to this embodiment, the maximum outer diameter of the valve body structure portion 243 is smaller than that of the first valve port 205 and the second valve port 206. Therefore, the valve shaft 24 can be assembled only from the upper end opening 201 side, which is excellent in ease of manufacture.

In the present embodiment, each tapered portion (first large tapered portion 244a, first small tapered portion 244c, second large tapered portion 245a, and second small tapered portion 245c) has a conical pedestal-like surface. Although it is a part, it can have other shapes. For example, each tapered portion may have a shape in which a plurality of conical base surfaces having different slopes are continuous (multi-step tapered shape), or the cross-sectional shape including the axis L may be a curved surface shape.

(Operation of flow path switching valve)
Next, the operation of the flow path switching valve 10 will be described. In FIG. 1, when a pulse signal having a predetermined number of pulses is applied from the outside to energize and excite the stator coil 53 of the stator 50, the magnetic force generated by the energization causes the rotor 30 to generate a rotational force by a predetermined angle. The rotor 30 and the valve shaft holder 32 are rotationally driven with respect to the guide bush 26 fixed to the valve body 20.

As a result, the valve shaft holder 32 is displaced in the axis L direction by the screw feed mechanism (also referred to as a drive mechanism) between the fixing screw portion 25 of the guide bush 26 and the moving screw portion 31 of the valve shaft holder 32. For example, even if the lower end of the valve shaft 24 comes into contact with the bottom surface of the lower expansion hole 203 of the valve body 20 due to stepping-out of the stepping motor, the upper stopper body 37 has not yet come into contact with the lower stopper body 27, and the valve. The rotor 30 and the valve shaft holder 32 further rotate and descend while the shaft 24 is in contact with the rotor 30. At this time, the relative downward displacement of the valve shaft holder 32 with respect to the valve shaft 24 is absorbed by the compression of the compression coil spring 34.

Further, when the rotor 30 further rotates and the valve shaft holder 32 is lowered, the upper stopper piece 37a of the upper stopper body 37 comes into contact with the lower stopper piece 27a of the lower stopper body 27. Due to the contact between the stopper pieces 27a and 37a, the lowering of the valve shaft holder 32 is forcibly stopped even if the stator 50 is continuously energized.

When a pulse signal having a reverse characteristic is applied to the stator 50, the rotor 30 and the valve shaft holder 32 are rotationally driven with respect to the guide bush 26 in the opposite direction to the above by a predetermined angle according to the number of pulses, and the screw feed mechanism is described above. As a result, the valve shaft holder 32 and the valve shaft 24 move upward.

In the flow path switching valve 10 of the present embodiment, the refrigerant that has flowed from the second pipe T2 into the intermediate expansion hole 204 of the valve body 20 is distributed to the first pipe T1 or the third pipe T3 and discharged.

First, as shown in FIG. 3, in a state where the lower end of the valve shaft 24 is in contact with the bottom surface of the lower expansion hole 203, the large diameter shaft portion 242 of the valve shaft 24 enters the first valve port 205, and the second valve shaft 24 is inserted. The second valve body portion 245 detaches from the two valve openings 206 (that is, the connecting shaft portion 246 enters). At this time, the amount of overlap of the large-diameter shaft portion 242 with respect to the first valve port 205 is set to OV1.

Here, the refrigerant that has flowed from the second pipe T2 into the intermediate expansion hole 204 of the valve body 20 is connected to the cross-sectional area α between the first valve port 205 and the large-diameter shaft portion 242 and the second valve port 206. It is divided into the first valve port 205 and the second valve port 206 according to the area ratio with the cross-sectional area β between the shaft portion 246 and the shaft portion 246. The refrigerant that has passed through the first valve port 205 passes through the upper expansion hole 202 and flows to the first pipe T1, and the refrigerant that has passed through the second valve port 206 passes through the lower expansion hole 203 and is the third. It flows to the pipe T3. The ratio of the amount of the refrigerant flowing through the first valve port 205 and the amount of the refrigerant flowing through the second valve port 206 is called a flow rate ratio.

In FIG. 2, the amount of the refrigerant flowing through the first valve port 205 is shown by the solid line X, and the amount of the refrigerant flowing through the second valve port 206 is shown by the dotted line Y. In the state of FIG. 3, the valve shaft lift amount shown by the point A in FIG. 2 is obtained, the amount of the refrigerant flowing through the first valve port 205 is the minimum, and the amount of the refrigerant flowing through the second valve port 206 is the maximum.

When the valve shaft 24 is raised from the point A, the upper end of the second small taper portion 245c passes radially inside the lower end of the second valve port 206, and the upper end of the first large taper portion 244a is the first. The valve port 205 is located on the inner side in the radial direction of the upper end, and at this time, the movement amount of the valve shaft 24 becomes equal to the overlap amount OV1. Such a state is shown in FIG. Until the upper end of the second small taper portion 245c is located radially inside the lower end of the second valve port 206, the amount of refrigerant flowing through the first valve port 205 is the minimum, and the upper end of the first large taper portion 244a is further located. , The amount of refrigerant flowing through the second valve port 206 remains maximum until it is located radially inside the upper end of the first valve port 205.

In the example of FIG. 2, after the upper end of the second small taper portion 245c passes radially inside the lower end of the second valve port 206, the upper end of the first large taper portion 244a is the upper end of the first valve port 205. It is located on the inner side in the radial direction, and the valve shaft lift amount at that time is shown at point B in FIG. Therefore, even after the amount of the refrigerant flowing through the second valve port 206 is reduced from the maximum value, there is a section in which the amount of the refrigerant flowing through the first valve port 205 is constant. However, both may be positioned in the reverse order of this example, or both upper ends may be positioned at the same time.

When the valve shaft 24 is raised from the point B, the second small taper portion 245c passes radially inside the lower end of the second valve port 206, and the first large taper portion 244a passes through the upper end of the first valve port 205. Passes inside in the radial direction of.

At this time, depending on the position of the valve shaft 24, the cross-sectional area α between the first large taper portion 244a and the first valve port 205, and the disconnection between the second small taper portion 245c and the second valve port 206. Area β changes. Therefore, according to the solid line X and the dotted line Y in FIG. 2, the amount of the refrigerant flowing through the first valve port 205 can be gradually increased, and the amount of the refrigerant flowing through the second valve port 206 can be gradually decreased.

Further, as the valve shaft 24 is raised, the upper end of the second cylindrical portion 245b passes radially inside the lower end of the second valve port 206, and the upper end of the first cylindrical portion 244b passes through the first valve port 205. It will be located on the inner side of the upper end in the radial direction. Such a state is shown in FIG.

In the example of FIG. 2, after the upper end of the second cylindrical portion 245b passes the radial inside of the lower end of the second valve port 206, the upper end of the first cylindrical portion 244b passes in the radial direction of the upper end of the first valve port 205. It is located inside, and the valve shaft lift amount at that time is shown by point C in FIG. However, both may be positioned in the reverse order of this example, or both upper ends may be positioned at the same time.

While the second cylindrical portion 245b is located radially inside the lower end of the second valve port 206 and the first cylindrical portion 244b is located radially inside the upper end of the first valve port 205, the cross-sectional area α And the cross-sectional area β are equal to each other, so that the amount of the refrigerant flowing through the first valve port 205 and the amount of the refrigerant flowing through the second valve port 206 are equal, that is, the flow rate ratio is 1.

When the valve shaft 24 is raised from the point C, the stroke intermediate point of the valve shaft 24 is reached. The valve shaft lift amount at this time is shown at point D in FIG. When the valve shaft 24 is further raised after passing through the midpoint of the stroke, the upper end of the second large taper portion 245a passes radially inside the lower end of the second valve port 206, and the first small taper portion 244c The upper end is located radially inside the upper end of the first valve port 205.

In the example of FIG. 2, after the upper end of the second large taper portion 245a passes radially inside the lower end of the second valve port 206, the upper end of the first small taper portion 244c is the upper end of the first valve port 205. It is designed to be located inward in the radial direction. FIG. 6 shows a state in which the upper end of the second large taper portion 245a is located radially inside the lower end of the second valve port 206, and the valve shaft lift amount at that time is shown by point E in FIG. However, both may be positioned in the reverse order of this example, or both upper ends may be positioned at the same time.

Between points C and E, the first cylindrical portion 244b is located radially inside the upper end of the first valve port 205, and the second cylindrical portion 245b is located radially inside the lower end of the second valve port 206. doing. Therefore, as shown by the solid line X and the dotted line Y in FIG. 2, the amount of the refrigerant flowing through the first valve port 205 and the amount of the refrigerant flowing through the second valve port 206 are maintained at equal amounts.

When the valve shaft 24 is raised from the point E, the upper end of the end shaft portion 247 passes radially inside the lower end of the second valve port 206, and the upper end of the connecting shaft portion 246 is the upper end of the first valve port 205. Will be located inward in the radial direction of.

In the example of FIG. 2, after the upper end of the end shaft portion 247 passes radially inside the lower end of the second valve port 206, the upper end of the connecting shaft portion 246 is radially inside the upper end of the first valve port 205. I try to be located. The state in which the upper end of the end shaft portion 247 is located radially inside the lower end of the second valve port 206 is shown in FIG. 7, and the valve shaft lift amount at that time is shown by point F in FIG. However, both may be positioned in the reverse order of this example, or both upper ends may be positioned at the same time.

The cross-sectional area α between the first small taper portion 244c and the first valve port 205, and the second large taper portion 245a and the second valve port 206 reach the point F, depending on the position of the valve shaft 24. The cross-sectional area β between them changes. Therefore, according to the solid line X and the dotted line Y in FIG. 2, the amount of the refrigerant flowing through the first valve port 205 can be gradually increased, and the amount of the refrigerant flowing through the second valve port 206 can be gradually decreased.

When the valve shaft 24 is raised from the point F, the amount of the refrigerant flowing through the first valve port 205 gradually increases until the upper end of the connecting shaft portion 246 is located radially inside the upper end of the first valve port 205. , The amount of the refrigerant flowing through the second valve port 206 is constant. After that, when the valve shaft 24 was further raised and the connecting shaft portion 246 was located radially inside the upper end of the first valve port 205, the end shaft portion 247 was located radially inside the lower end of the second valve port 206. There is up to. At this time, the valve shaft 24 reaches the stroke end (moving end). This state is shown in FIG. 8, and the valve shaft lift amount at that time is shown by a point G in FIG.

The connecting shaft portion 246 is located radially inside the upper end of the first valve port 205, and the end shaft portion 247 is located radially inside the lower end of the second valve port 206 until the valve shaft 24 reaches the stroke end. Therefore, the state in which the amount of the refrigerant flowing through the first valve port 205 is maximized and the amount of the refrigerant flowing through the second valve port 206 is minimized is maintained.
In the present embodiment, when the first cylindrical portion 244b of the first valve body portion 244 is located inside the first valve port 205 in the radial direction, the second valve body portion 245 is located inside the second valve port 206 in the radial direction. It is preferable that at least a part of the second cylindrical portion 245b is located.

(Comparison example)
FIG. 9 is a cross-sectional view similar to FIG. 3 showing the periphery of the valve body structure portion 243'in the comparative example. In this comparative example, the valve body structure portion 243'of the valve shaft 24'connects the first taper portion 244', the second taper portion 245', the first taper portion 244', and the second taper portion 245'. It has a connecting shaft portion 246 and an end shaft portion 247. That is, the valve body structure portion 243'of the comparative example does not have the first cylindrical portion and the second cylindrical portion. Since the other configurations are the same as those in the above-described embodiment, the same reference numerals are given and the description thereof will be omitted.

In FIG. 2, the amount of the refrigerant flowing in the first pipe T1 when the valve body structure portion 243'of the comparative example is used is shown by the alternate long and short dash line W, and the amount of the refrigerant flowing in the third pipe T3 is indicated by the alternate long and short dash line Z. .. Here, when the flow path switching valve of the comparative example is used, the flow rate ratio is 1 only at the point D where the alternate long and short dash line W and the alternate long and short dash line Z intersect.

In the comparative example, when the valve body 20 and the valve shaft 24'are manufactured in an ideal shape and the assembly error is zero, the flow rate ratio is set to 1 by keeping the valve shaft 24'at the position of the point D. be able to. However, in reality, there is a manufacturing error between the valve body 20 and the valve shaft 24', and an assembly error also occurs. In addition, the control position of the valve shaft 24'may also shift due to stepping-out of the stepping motor or the like. In such a case, since the positions of the alternate long and short dash line W and the alternate long and short dash line Z change, it is difficult to obtain the flow rate ratio 1 at the point D.

On the other hand, according to the present embodiment, since the valve body structure portion 243 of the valve shaft 24 has the first cylindrical portion 244b and the second cylindrical portion 245b, it has a relatively wide range between points C and E. A flow rate ratio of 1 can be realized. Therefore, even if manufacturing errors or assembly errors occur in the valve body 20 and the valve shaft 24, or step-out occurs in the stepping motor, as long as those effects do not occur beyond points C to E. , The flow rate ratio 1 can be secured. Therefore, the flow path switching valve 10 is not required to have strict manufacturing error or assembly error, and manufacturing easiness can be ensured.

(Modification example)
FIG. 10 is an enlarged view of the vicinity of the first valve body portion 244A of the valve shaft 24A according to the modified example of the present embodiment as viewed from the side. The first valve body portion 244A of this modification includes a first large taper portion 244Aa connected to the large diameter shaft portion 242, a first cylindrical portion 244Ab connected to the first large taper portion 244Aa, and a first cylindrical portion 244Ab. It is composed of a first small taper portion 244Ac connected to the connecting shaft portion 246. Since the other configurations are the same as those in the above-described embodiment including the shape of the second valve body portion, the same reference numerals are given and duplicate description will be omitted.

The first large taper portion 244a, the first cylindrical portion 244b, and the first small taper portion 244c of the above embodiment are shown by overlapping with a dotted line in FIG. As is clear, the outer diameter of the first cylindrical portion 244Ab of this modification is smaller than that of the above embodiment, and the shapes of the first large taper portion 244Aa and the first small taper portion 244Ac are correspondingly smaller. Is also changing.

FIG. 11 is a diagram showing the flow path characteristics of the flow path switching valve of this modified example. The dotted line Y is the same as that shown in FIG. 2, but the solid line XA changes according to the shape of the first valve body portion 244A. More specifically, between points H and I, the first cylindrical portion 244Ab is located radially inside the upper end of the first valve port 205 (see FIG. 3), and the cross-sectional area between the two is α. Further, the second cylindrical portion 245b is located radially inside the lower end of the second valve port 206, and the cross-sectional area between the two is β.

At this time, assuming that the amount of the refrigerant flowing in from the second pipe T2 is Q, the amount of the refrigerant flowing in the first pipe T1 between the points H and I is Q · α / (α + β), and the third pipe T3 The amount of the flowing refrigerant can be set to Q · β / (α + β), and distribution can be performed in an arbitrary amount.

The present invention is not limited to the above-described embodiment. Within the scope of the present invention, any component of the above-described embodiment can be modified. In addition, any component can be added or omitted in the above-described embodiment. For example, a solenoid actuator may be used instead of the stepping motor, or a planetary gear mechanism that decelerates and transmits the rotational force of the rotor may be mounted.

10 Flow path switching valve 20 Valve body 24, 24A Valve shaft 25 Fixed thread part (male thread part)
26 Guide bush 27 Lower stopper body 30 Rotor 31 Moving thread part (female thread part)
32 Valve shaft holder 33 Push nut 34 Compression coil spring 35 Return spring 36 Support ring 37 Upper stopper body 40 Can 41 Circular plate 50 Stator VC Valve chamber

The flow path switching valve according to the present invention is
A valve chamber, a first connecting portion connecting the first pipe and the valve chamber, a second connecting portion connecting the second pipe and the valve chamber, and a third connecting portion connecting the third pipe and the valve chamber. It has a first valve port provided between the first connection portion and the second connection portion, and a second valve port provided between the second connection portion and the third connection portion. With the valve body
A valve shaft arranged in the valve chamber so as to be movable in the axial direction and inserted through the first valve port and the second valve port,
Have,
The valve shaft has a first valve body portion that controls the passing flow rate of the fluid flowing through the first valve port, and a second valve body portion that controls the passing flow rate of the fluid flowing through the second valve port.
The first valve body portion and the second valve body portion are provided with a tapered portion and a cylindrical portion, respectively.
The maximum outer diameter of the second valve body portion is smaller than the inner diameters of the first valve port and the second valve port.

Claims (6)

A valve chamber, a first connecting portion connecting the first pipe and the valve chamber, a second connecting portion connecting the second pipe and the valve chamber, and a third connecting portion connecting the third pipe and the valve chamber. It has a first valve port provided between the first connection portion and the second connection portion, and a second valve port provided between the second connection portion and the third connection portion. With the valve body
A valve shaft movably arranged in the valve chamber and inserted into the first valve port and the second valve port,
Have,
The valve shaft has a first valve body portion that controls the passing flow rate of the fluid flowing through the first valve port, and a second valve body portion that controls the passing flow rate of the fluid flowing through the second valve port.
The first valve body portion and the second valve body portion are provided with a tapered portion and a cylindrical portion, respectively.
The maximum outer diameter of the second valve body portion is smaller than the inner diameters of the first valve port and the second valve port.
A flow path switching valve characterized by this. When the cylindrical portion of the first valve body portion is located inside the first valve port in the radial direction, at least a part of the cylindrical portion of the second valve body portion is located inside the radial direction of the second valve port. Is set to
The flow path switching valve according to claim 1. Both the first valve body portion and the tapered portion of the second valve body portion have a large tapered portion connected to one end of the cylindrical portion and a small tapered portion connected to the other end of the cylindrical portion. The flow path switching valve according to claim 1 or 2, wherein the flow path switching valve is provided. At the moving end of the valve shaft, the end of the valve shaft abuts on the bottom surface of the valve body.
The flow path switching valve according to any one of claims 1 to 3. The valve shaft has a connecting shaft portion that connects the first valve body portion and the second valve body portion, and the connecting shaft portion has a smaller diameter than the first valve body portion and the second valve body portion. be,
The flow path switching valve according to any one of claims 1 to 4, wherein the flow path switching valve is characterized in that. The first valve body portion and the second valve body portion have the same shape.
The flow path switching valve according to any one of claims 1 to 5, wherein the flow path switching valve is characterized in that.

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