JP7645217B2 - Method for controlling rotary switching valve - Google Patents

Description

The present invention relates to a method for controlling a rotary switching valve.

Conventionally, a rotary switching valve is known that includes a valve housing, a main valve, an auxiliary valve, and a drive unit. The main valve rotates via the auxiliary valve, which is driven to rotate by the drive unit, to switch the port that is communicated by the valve passage of the main valve. The drive unit has a worm wheel rotatably arranged on a central axis, a worm gear meshed with the worm wheel, and a motor that rotates the worm gear. The worm wheel is connected to the auxiliary valve via a cam unit in a state in which its rotation is restricted. The main valve is restricted in rotation at two switching positions by abutting against a stopper pin of the valve housing, and the auxiliary valve is either driven to rotate until it abuts against the stopper portion of the main valve, or driven to rotate to a predetermined stop position with the biasing force of a spring acting on the main valve.

JP 2021-124119 A

In the above-mentioned rotary switching valve, when the rotational drive of the auxiliary valve is stopped, the auxiliary valve is either directly in contact with and pressed against the main valve, or is biased by a spring between it and the main valve, and this force (pressing force or biasing force) can cause the auxiliary valve to tilt, creating a gap between the pressure equalizing hole of the main valve and the sealing surface of the auxiliary valve, which can cause refrigerant to leak to the low-pressure side. In addition, the force acting on the auxiliary valve is also transmitted to the worm wheel and worm gear, and surface pressure is applied to these meshing parts, which can cause creep deformation over the long term and reduce operability if the worm wheel and worm gear are made of plastic.

The present invention aims to provide a method for controlling a rotary switching valve that can prevent fluid leakage into the pressure equalizing hole by suppressing tilt of the auxiliary valve, and can prevent creep deformation by suppressing the transmission of force from the auxiliary valve to the drive unit, thereby stabilizing operability.

In order to solve the above problems and achieve the object, the present invention provides a control method for a rotary switching valve comprising: a valve body constituting a valve chamber; a valve seat portion having a plurality of ports opening into the valve chamber; a main valve provided inside the valve body to be rotatable about a central axis intersecting the valve seat portion; an auxiliary valve provided to be rotatable about the central axis and for opening and closing a pressure equalizing hole of the main valve; and a drive portion for rotationally driving the auxiliary valve, wherein the main valve has an auxiliary valve stopper that abuts against the auxiliary valve to stop rotation of the auxiliary valve, The drive unit includes an electric motor having a drive shaft, and after rotating the drive shaft to a predetermined rotational position where the auxiliary valve abuts the auxiliary valve stopper, the electric motor is controlled to rotate the drive shaft in the reverse direction by a predetermined return angle , and the return angle is set to be larger than a lower limit angle which is an angle based on at least one of the backlash occurring within the drive unit and the backlash occurring between the central shaft supporting the auxiliary valve and the auxiliary valve, and smaller than an upper limit angle which is an angle based on the rotational position of the pressure equalizing hole and the auxiliary valve .

According to the present invention, even if the sub-valve is tilted by being pressed against the main valve when the drive shaft is rotated to a predetermined rotational position where the sub-valve abuts against the sub-valve stopper, the electric motor is controlled to rotate the drive shaft in the reverse direction by a predetermined return angle, thereby reducing the pressing force and eliminating the tilt of the sub-valve. This makes it possible to suppress leakage of fluid into the pressure equalizing hole due to the tilt of the sub-valve. In addition, it is possible to suppress the continuous application of unexpected forces to the drive unit due to the tilt of the sub-valve. Therefore, it is possible to obtain a control method for a rotary switching valve that can prevent fluid leakage into the pressure equalizing hole by suppressing the tilt of the sub-valve, and can prevent creep deformation by suppressing the transmission of force from the sub-valve to the drive unit, thereby stabilizing operability.

The drive unit is preferably provided with a worm that rotates with the rotation of the drive shaft and a worm wheel that can rotate by meshing with the worm, and the lower limit angle is a first angle that is an angle at which the worm rotates by an amount corresponding to the meshing play between the worm and the worm wheel, the return angle is greater than the first angle, and the upper limit angle is a second angle that is set based on the rotation position of the sub-valve at which the closed state in which the pressure equalizing hole is closed by the sub-valve is maintained. According to this configuration, by making the return angle of the drive shaft of the electric motor greater than the first angle, which is the lower limit angle, and by rotating the drive shaft in the reverse direction as described above, the surface pressure acting on the meshing portion of the worm and the worm wheel through the sub-valve in a state pressed against the main valve can be reduced. This makes it possible to prevent creep deformation of the worm and the worm wheel. In addition, when the sub-valve, which is located at a certain rotational position, is tilted due to being pressed against the main valve, the tilt of the sub-valve can often be eliminated by rotating the drive shaft in the reverse direction as described above by a value greater than the lower limit angle. This makes it easier to prevent fluid leakage into the pressure equalizing hole due to tilt of the sub-valve. In addition, by making the upper limit angle of the return angle smaller than the second angle that is set based on the rotational position of the sub-valve at which the pressure equalizing hole is maintained in a closed state, the pressure equalizing hole can be reliably maintained in a closed state even when the drive shaft is rotated in the reverse direction as described above, so that fluid leakage into the pressure equalizing hole can be reliably prevented.

The worm wheel and the sub-valve are connected to each other by a fitting structure capable of transmitting a rotational force, and the lower limit angle is an angle obtained by adding the first angle to a third angle, which is an angle at which the worm wheel rotates by an amount corresponding to a second backlash, which is a backlash in the rotational direction between the worm wheel and the sub-valve in the fitting structure, and it is preferable that the return angle is greater than the angle obtained by adding the first angle to the third angle. According to this configuration, the sum of the third angle and the first angle is set as the lower limit angle, and the return angle is set to an angle greater than this lower limit angle. In addition to the surface pressure acting on the meshing portion of the worm and the worm wheel, the force acting on the fitting structure of the worm wheel and the sub-valve through the sub-valve pressed against the main valve can be reduced by rotating the drive shaft in the reverse direction as described above. This makes it possible to prevent creep deformation of the fitting structure of the worm, worm wheel, and sub-valve.

As described above, when the sub-valve, which is located at a predetermined rotational position, is tilted due to being pressed against the main valve, the tilt of the sub-valve may be eliminated by rotating the drive shaft in the reverse direction as described above by a value greater than the lower limit angle. However, since the lower limit angle is set to the third angle plus the first angle, the possibility of eliminating the tilt of the sub-valve is increased compared to when the lower limit angle is set to the first angle as described above. Therefore, it is easier to prevent fluid leakage into the pressure equalizing hole due to tilt of the sub-valve than when the lower limit angle is set to the first angle.

The lower limit angle is preferably an angle obtained by adding the first and third angles to a fourth angle, which is a margin angle for completely eliminating the inclination of the sub-valve at the predetermined rotational position. According to this configuration, the sum of the first, third and fourth angles is set as the lower limit angle, and the return angle is set to an angle greater than this lower limit angle. Therefore, when the sub-valve at the predetermined rotational position is inclined due to being pressed against the main valve, the inclination of the sub-valve can be completely eliminated by rotating the drive shaft in the reverse direction as described above, which is greater than the lower limit angle. Therefore, leakage of fluid into the pressure equalizing hole due to inclination of the sub-valve can be more reliably prevented. In addition, creep deformation of the fitting structure of the worm, worm wheel and sub-valve can be prevented.

The main valve is provided with a sub-valve seat surface where the pressure equalizing hole opens toward the sub-valve, and the sub-valve is provided with a seal surface that closes the pressure equalizing hole in a parallel state that is in contact with the sub-valve seat surface, and the total angle of the first angle, the third angle, and the fourth angle is preferably the rotation angle of the drive shaft for the seal surface to return to the parallel state from the non-parallel state that is not parallel to the sub-valve seat surface when the electric motor is controlled to rotate the drive shaft in the reverse direction by the predetermined return angle. With this configuration, even if the pressure equalizing hole is unexpectedly opened by the sub-valve that has become non-parallel, the sub-valve can be returned to the parallel state by rotating the drive shaft as described above by a value greater than the total angle of the first angle, the third angle, and the fourth angle. Therefore, it is possible to more reliably prevent fluid leakage into the pressure equalizing hole due to the tilt of the sub-valve.

In addition, the main valve is provided with a sub-valve seat surface where the pressure equalizing hole opens toward the sub-valve, and the sub-valve is provided with a seal surface set to be equal to or larger than the area of the part surrounded by the opening edge of the pressure equalizing hole, and the seal surface is arranged to open and close the pressure equalizing hole while sliding against the sub-valve seat surface in accordance with the rotation of the sub-valve, and it is preferable that the rotation position of the sub-valve that is the basis for setting the second angle is a position where the edge of the seal surface in the state where the pressure equalizing hole is closed overlaps the opening edge of the pressure equalizing hole when the seal surface closing the pressure equalizing hole moves in the sliding contact direction. According to this configuration, the rotation position of the sub-valve that is the basis for setting the second angle, which is the upper limit angle of the return angle, is a position where the edge of the seal surface in the state where the pressure equalizing hole is closed overlaps the opening edge of the pressure equalizing hole when the seal surface closing the pressure equalizing hole moves in the sliding contact direction. Therefore, when the drive shaft is rotated in the reverse direction as described above, the rotation of the auxiliary valve can be stopped just before the edge of the seal surface moving in the sliding direction is positioned within the opening of the pressure equalizing hole (i.e., just before the pressure equalizing hole opens), preventing the auxiliary valve from rotating beyond this position and opening the pressure equalizing hole.

According to the present invention, it is possible to obtain a control method for a rotary switching valve that can prevent fluid leakage into the pressure equalizing hole by suppressing tilt of the auxiliary valve, and can prevent creep deformation by suppressing the transmission of force from the auxiliary valve to the drive unit, thereby stabilizing operability.

FIG. 2 is an assembled cross-sectional view showing a closed state in which a pressure equalizing hole of the rotary switching valve according to one embodiment of the present invention is closed. FIG. 4 is an assembled cross-sectional view showing an open state in which a pressure equalizing hole of the rotary switching valve is open. 1A is a perspective view of the main valve as viewed obliquely from above, and FIG. 1B is a perspective view of the main valve as viewed obliquely from below. 1A is a perspective view of the sub-valve seen from diagonally above, and FIG. 1B is a perspective view of the sub-valve seen from diagonally below. 1A is a bottom view showing a flow path switching position of the main valve during cooling, and FIG. 1B is a bottom view showing a flow path switching position of the main valve during heating. 6A is a schematic diagram of a main valve and an auxiliary valve showing a first operation of the rotary switching valve, and FIG. 6B is a cross-sectional view taken along line A-A in FIG. 6A. 7A is a schematic diagram of a main valve and an auxiliary valve showing a second operation of the rotary switching valve, and FIG. 7B is a cross-sectional view taken along line A-A in FIG. 7A. 8A is a schematic diagram of a main valve and an auxiliary valve showing a third operation of the rotary switching valve, and FIG. 8B is a cross-sectional view taken along line A-A in FIG. 8A . 9A is a schematic diagram of a main valve and an auxiliary valve showing a fourth operation of the rotary switching valve, and FIG. 9B is a cross-sectional view taken along line A-A in FIG. 9A. 10A is a schematic diagram of a main valve and an auxiliary valve showing a fifth operation of the rotary switching valve, and FIG. 10B is a cross-sectional view taken along line A-A in FIG. 10A. 1A is a diagram showing the position of the sub-valve when the drive shaft is rotated by a lower limit angle, and FIG. 1B is a diagram showing the position of the sub-valve when the drive shaft is rotated by an upper limit angle. 1 is a cross-sectional view showing a state in which rotation of the sub-valve and the main valve about the central axis is restricted. FIG. 13 is a cross-sectional view taken along line AA in FIG. 12, showing the inclination of the sub-valve. 14A is a plan view showing a drive unit, and FIG. 14B is a partially enlarged view of region A in FIG. 14A. 15A is a cross-sectional view showing a state in which the central shaft supports the sub-valve, and FIG. 15B is a cross-sectional view taken along line BB in FIG. 15A. FIG. 2A is a schematic diagram of the refrigeration cycle system showing a state during cooling operation, and FIG. 2B is a schematic diagram of the refrigeration cycle system showing a state during heating operation.

The following describes an embodiment of the present invention based on Figures 1 to 16. In the drawings, arrows X and Y are mutually orthogonal directions, and arrow X is the axial direction of the valve body 1 and the central axis 6, and is referred to as the "axial X direction." One side of the axial X direction is referred to as the "upper side X1," and the other side is referred to as the "lower side X2." The intersecting direction that intersects with the axial X direction is indicated by arrow Y and is referred to as the "radial direction Y." In particular, in the radial direction Y, the side where the central axis 6 is located is referred to as the "inner side," and the opposite side of the inner side is referred to as the "outer side." This is merely for the convenience of explanation, and does not necessarily match the direction in the actual use state of the rotary switching valve 100, and does not limit the direction in the actual use state of the rotary switching valve 100.

The rotary switching valve 100 comprises a valve body 1, a valve seat member 2, a main valve 3, an auxiliary valve 4, a drive unit 5, and a central shaft 6. The valve body 1 comprises a first cylindrical portion 10 extending in the direction of the axis X, and a second cylindrical portion 11 with a bottom that is continuous with the first cylindrical portion 10 and has a smaller diameter than the first cylindrical portion 10, and accommodates the main valve 3, the auxiliary valve 4, the drive unit 5, and the central shaft 6. The inside of the first cylindrical portion 10 forms a valve chamber 10a. The inside of the second cylindrical portion 11 forms a housing portion 11a that mainly houses the drive unit 5, etc.

The valve seat member 2 comprises a cylindrical valve seat portion 20 and a flange portion 21 formed on the outer periphery of the valve seat portion 20. The valve seat portion 20 is fitted into the valve body 1 so that its outer periphery contacts the inner periphery of the first cylindrical portion 10, and its upper surface forms a valve seat surface 20a extending in the radial direction Y. As shown in Figures 5 (A) and (B), the valve seat portion 20 is provided with four ports 20D, 20S, 20C, and 20E that penetrate from the lower end of the valve seat portion 20 to the valve seat surface 20a and open into the valve chamber 10a. Each of the ports 20D, 20S, 20C, and 20E opens at positions spaced 90° apart from each other.

As shown in Figures 16(A) and (B), the four ports are D port 20D, which is connected to the valve chamber 10a and the refrigerant discharge side of the compressor P, S port 20S, which is connected to the refrigerant suction side of the compressor P, C switch port 20C, which is connected to the outdoor heat exchanger 60 side, and E switch port 20E, which is connected to the indoor heat exchanger 80 side. Each of the ports 20D, 20S, 20C, and 20E is connected to a coupling tube 8 (only shown in Figure 1) to form a refrigerant flow path. The flange portion 21 is fixed to the valve body 1 by welding with its upper surface in contact with the lower end surface of the first cylindrical portion 10.

The main valve 3 is a member made of resin, and is provided inside the valve body 1 so as to be rotatable around the central axis 6 and displaceable in the direction of the axis X. As shown in Figures 3(A) and (B), the main valve 3 has a bowl-shaped bowl portion 30 that opens to the lower side X2 (the valve seat portion 20 side), and a cylindrical piston portion 31 that is continuous with the bowl portion 30 and extends to the upper side X1. The bowl portion 30 is formed with a low-pressure flow path 30L and a high-pressure flow path 30H that open toward the valve seat surface 20a, and a pressure equalizing hole 30a that communicates from the ceiling of the low-pressure flow path 30L to the storage portion 11a.

The low-pressure flow passage 30L is a valve passage that connects two adjacent ports among the above-mentioned ports 20D, 20S, 20C, and 20E, and is provided opposite the high-pressure flow passage 30H across the central axis 6. As shown in FIG. 3B, the low-pressure flow passage 30L is provided with a rib 32 that protrudes from its opening edge toward the lower side X2, and the lower end surface of the rib 32 forms a low-pressure seal surface 32a. As shown in FIG. 1, the low-pressure seal surface 32a is capable of sliding contact with the valve seat surface 20a, and two of the above-mentioned four ports 20D, 20S, 20C, and 20E are connected by a space surrounded by the low-pressure seal surface 32a and the valve seat surface 20a and separated from the valve chamber 10a.

As shown in FIG. 3B, the low-pressure flow passage 30L has a reinforcing member 7 installed from its inner wall in the radial direction Y to its outer wall in the radial direction Y. The reinforcing member 7 is a member for preventing deformation of the low-pressure flow passage 30L due to stress caused by the pressure difference between the inside and outside of the main valve 3, and is formed into a rod shape from a material such as metal or resin, and is fixed into the low-pressure flow passage 30L by press-fitting or the like.

The high-pressure flow passage 30H is a valve passage that connects two adjacent ports among the ports 20D, 20S, 20C, and 20E. As shown in Figs. 1 and 2, a notch 30H1 is formed in the radially outer wall of the high-pressure flow passage 30H toward the inside in the radial direction Y when viewed in cross section in the figure. This makes the high-pressure flow passage 30H a constantly open space that is not separated from the valve chamber 10a.

A pair of sliding ribs 30b protruding toward the lower side X2 are formed on the bottom surface of the bowl portion 30. As shown in FIG. 3(B), the sliding ribs 30b are formed at intervals in the circumferential direction on the semicircular portion on the side where the high-pressure flow path 30H is formed on the bottom surface of the bowl portion 30.

The piston portion 31 is formed so that a piston ring R is fitted around it, and as shown in FIG. 1, the piston ring R is adapted to slide against the inner peripheral surface of the second cylindrical portion 11 when the main valve 3 is displaced in the axial direction X. A cylindrical recess that opens to the upper side X1 is formed in the center of the piston portion 31, and this recess constitutes the sub-valve storage chamber 31a that houses the sub-valve 4.

As shown in FIG. 3(A), two columnar auxiliary valve stoppers 31a1 are formed on the inner peripheral surface of the auxiliary valve chamber 31a, protruding inward in the radial direction Y and extending in the axial direction X, spaced apart from each other in the circumferential direction around the central axis 6 (around the axial line X). The auxiliary valve stoppers 31a1 come into contact with the enlarged diameter portion 40a of the auxiliary valve 4, which will be described later, to stop the rotation of the auxiliary valve 4.

The main valve side clutch part 33 is formed on the bottom surface of the auxiliary valve storage chamber 31a. The main valve side clutch part 33 is composed of three main valve protrusions 33a that are convex toward the upper side X1 and are formed at equal intervals in the circumferential direction on the circumference around the central axis 6. Each main valve protrusion 33a has a trapezoidal cross-sectional shape around the central axis 6, and both left and right ends around the central axis 6 are tapered surfaces that incline in a direction that approaches each other as they approach the upper side X1. One of these main valve protrusions 33a has an opening at the end of the upper side X1 of the above-mentioned pressure equalizing hole 30a. The upper surface of the main valve protrusion 33a where this pressure equalizing hole 30a opens constitutes the auxiliary valve seat seat surface 33a1 that contacts the seal surface 42a1, which is the lower end surface of the auxiliary valve protrusion 42a described later. In other words, the main valve 3 is provided with the auxiliary valve seat seat surface 33a1 where the pressure equalizing hole 30a opens toward the auxiliary valve 4.

The center of the bottom surface of the auxiliary valve storage chamber 31a constitutes a bearing portion for the central shaft 6, and a shaft insertion hole 3a is formed in the center of this bearing portion, penetrating along the axis X to the lower end of the bowl portion 30. A lower portion 6b of the central shaft 6, which will be described later, is inserted into the shaft insertion hole 3a, and the main valve 3 is supported so as to be rotatable around the central shaft 6 and displaceable in the axis X between a first switching position (switching position, position shown in FIG. 5(A)) in which the central shaft 6 abuts against a main valve stopper 9, which will be described later, and a second switching position (switching position, position shown in FIG. 5(B)).

The auxiliary valve 4 is a member made of metal, and like the main valve 3, is provided so as to be rotatable around the central axis 6 and displaceable in the axial direction X. As shown in Figs. 4(A) and (B), the auxiliary valve 4 has a substantially disk-shaped flange portion 40 accommodated in the auxiliary valve accommodation chamber 31a, and a boss portion 41 formed in the center of the flange portion 40 and extending in the axial direction X. Approximately half of the circumferential portion of the flange portion 40 is formed with an enlarged diameter portion 40a that protrudes radially Y outward from the other portions, and one circumferential end of the enlarged diameter portion 40a is configured to abut against one of the auxiliary valve stoppers 31a1 described above, and the other circumferential end of the enlarged diameter portion 40a is configured to abut against the other of the auxiliary valve stoppers 31a1.

Specifically, when the auxiliary valve 4 rotates around the central axis 6 while the main valve 3 is in contact with the main valve stopper 9 at the first or second switching position and its rotation is restricted, the circumferential one end or the circumferential other end of the enlarged diameter portion 40a abuts against the auxiliary valve stopper 31a1. This abutment restricts the rotation of the auxiliary valve 4 around the central axis 6. As shown in FIG. 12, the angle of the portion around the central axis 6 from the circumferential one end to the circumferential other end of the enlarged diameter portion 40a where there is no enlarged diameter portion 40a is approximately 210°. Depending on the positional relationship (how many degrees apart in the circumferential direction) of each auxiliary valve stopper 31a1 of the main valve 3, the maximum amount of rotation of the auxiliary valve 4 around the central axis 6 relative to the valve body 1 is set to approximately 210°.

The sub-valve clutch part 42 is formed on the underside of the flange part 40. The sub-valve clutch part 42 is formed by three sub-valve protrusions 42a that are convex toward the lower side X2 on the same circumference as the main valve protrusion 33a and are formed at equal intervals in the circumferential direction on the circumference around the central axis 6. One of the main valve protrusions 33a can be positioned between one sub-valve protrusion 42a and the other sub-valve protrusion 42a, so that the main valve clutch part 33 and the sub-valve clutch part 42 mesh with each other. The sub-valve protrusion 42a has a trapezoidal cross-sectional shape around the central axis 6, and the left and right ends around the central axis 6 are tapered surfaces that are inclined in a direction that approaches each other as they approach the lower side X2.

The lower end surface of the auxiliary valve protrusion 42a constitutes the seal surface 42a1 that contacts the auxiliary valve seat seat surface 33a1 as described above. The seal surface 42a1 is configured to open and close the pressure equalizing hole 30a while sliding against the auxiliary valve seat seat surface 33a1 in accordance with the rotation of the auxiliary valve 4, and is configured to close the pressure equalizing hole 30a in a parallel state in contact with the auxiliary valve seat seat surface 33a1, thereby closing the pressure equalizing hole 30a. The area of the seal surface 42a1 is set to be equal to or greater than the area of the part surrounded by the opening edge of the pressure equalizing hole 30a. Therefore, even if the auxiliary valve 4 with the pressure equalizing hole 30a in a closed state rotates around the central axis 6 and the seal surface 42a1 moves accordingly, the pressure equalizing hole 30a does not open immediately. That is, after the edge of the moving seal surface 42a1 overlaps with the opening edge of the pressure equalizing hole 30a, when the seal surface 42a1 moves further and its edge is positioned within the opening edge of the pressure equalizing hole 30a, the pressure equalizing hole 30a begins to open and enters an open state. In this embodiment, when the auxiliary valve 4 that closes the pressure equalizing hole 30a moves in the sliding contact direction, the position of the auxiliary valve 4 where the edge of the seal surface 42a1 in the state where the pressure equalizing hole 30a is closed overlaps with the opening edge of the pressure equalizing hole 30a is defined as the closed maintenance limit position (the rotational position of the auxiliary valve 4 where the edge of the seal surface 42a1 in the state where the pressure equalizing hole 30a is closed overlaps with the opening edge of the pressure equalizing hole 30a, see FIG. 11(B)). This definition will be used in the explanation of the fifth operation e described below.

On the underside of the flange portion 40, between one sub-valve protrusion 42a and the other sub-valve protrusion 42a, a pressure equalizing passage 43 that can communicate with the pressure equalizing hole 30a is formed. Therefore, when the seal surface 42a1 of the sub-valve protrusion 42a closes the pressure equalizing hole 30a, the high-pressure valve chamber 10a and the low-pressure passage 30L are separated, but when the pressure equalizing passage 43 and the pressure equalizing hole 30a are in communication, the pressure of the fluid on the upper side X1 outside the main valve 3 escapes into the low-pressure passage 30L (low-pressure side), so that the pressures on the upper side X1 of the main valve 3 and the low-pressure passage 30L are equalized.

A square hole 41a (fitting structure) that opens to the upper side X1 is formed in the center of the boss portion 41. The square hole 41a is a portion that allows the auxiliary valve 4 and the worm wheel 50 described later to transmit rotational force around the central axis 6 to each other, and is formed so that the cam portion 50a of the worm wheel 50 can be fitted into it, as shown in Figures 15 (A) and (B). A shaft insertion hole 4a that penetrates along the axis X direction to the lower end of the flange portion 40 is formed in the center of the bottom of the square hole 41a. An upper portion 6a of the central shaft 6 described later is inserted into the shaft insertion hole 4a, thereby supporting the auxiliary valve 4 so that it can rotate around the central axis 6 and be displaced in the axis X direction.

The drive unit 5 is a part that drives the sub-valve 4 to rotate, and as shown in Figs. 1 and 2, has a resin worm wheel 50 rotatably arranged on the central shaft 6, a metal worm 51 arranged to mesh with the worm wheel 50, a stepping motor (electric motor) (not shown) having a drive shaft that drives the worm 51 to rotate, and a coil spring 52 arranged between the worm wheel 50 and the sub-valve 4 to bias the sub-valve 4 to the lower side X2. The worm wheel 50 is a part that can rotate by meshing with the worm 51, has a cam portion 50a that protrudes to the lower side X2, and is rotatably arranged on the central shaft 6 by the cam portion 50a. The cam portion 50a is a part that constitutes a fitting structure together with the above-mentioned square hole 41a, and is fitted into the square hole 41a of the sub-valve 4.

That is, the worm wheel 50 and the sub-valve 4 are connected by the square hole 41a and the cam portion 50a, which are fitted together. As a result, the sub-valve 4 and the worm wheel 50 become one unit and rotate together around the central axis 6 in cooperation with each other. When the square hole 41a and the cam portion 50a are fitted together, a predetermined gap (backlash) is created, which is a fitting backlash S1, to avoid interference between them. For example, as shown in FIG. 15(A), the fitting backlash S1 includes a first backlash S10, which is a gap (backlash) between the square hole 41a and the cam portion 50a in the axis X direction, and a second backlash S11, which is a gap (backlash) between the square hole 41a and the cam portion 50a around the central axis 6 (the rotation direction of the worm wheel 50 and the sub-valve 4 in the fitting structure).

The worm 51 is fixed to the drive shaft of the stepping motor described above. The worm 51 meshes with the worm wheel 50, rotates with the rotation of the drive shaft, and transmits the rotational force to the worm wheel 50. As shown in FIG. 14(B), the meshing portion between the worm wheel 50 and the worm 51 is set to have a predetermined gap (backlash), that is, backlash S2 (meshing backlash), to avoid interference between them.

The central shaft 6 is a main shaft extending in the direction of the axis X. As shown in Figs. 1 and 2, the central shaft 6 has an upper part 6a that is inserted into the center of the worm wheel 50 and the shaft insertion hole 4a of the sub-valve 4, and a lower part 6b that is formed with a smaller diameter than the upper part 6a and is inserted into the shaft insertion hole 3a of the main valve 3. A ball 6c is fixed to the upper end of the upper part 6a by crimping an annular rim, and the upper part 6a is supported via the ball 6c in a bearing groove provided in the center of the ceiling wall of the second cylindrical part 11 of the valve body 1. The lower end of the lower part 6b is supported by a bearing groove provided in the center of the valve seat part 20 of the valve seat member 2. A washer 61 is fitted into the continuous part between the upper part 6a and the lower part 6b, and the force when the main valve 3 rises to the upper side X1 is transmitted to the central shaft 6 via the washer 61.

In FIG. 15(A), the outer peripheral surface of the central shaft 6 is in contact with the inner peripheral surfaces of the shaft insertion hole 4a and the shaft insertion hole 3a, but between the outer peripheral surface and the inner peripheral surface, there is a gap (backlash) between the main shafts S3 (backlash between the central shaft 6 and the sub-valve 4) to prevent interference between them.

The stepping motor of the drive unit 5 can adjust the direction and amount of rotation of the drive shaft by a control unit (not shown). For example, in this embodiment, by sending a specific pulse from the control unit, the drive shaft is rotated in a first direction, which rotates the sub-valve 4 counterclockwise around the central axis 6, and in a second direction, which is the opposite direction to the first direction. The relationship between the specific pulse and the rotation angle of the sub-valve 4, assuming that there is no backlash (S1, S2, S3), is, for example, as follows:

6° at 40 pulses, 20° at 132 pulses, 210° at 1400 pulses, etc. Note that 210° at 1400 pulses means that by sending 1400 pulses to the stepping motor and rotating the drive shaft in the first or second direction, the sub-valve 4 can be rotated the maximum amount of rotation around the central axis 6 of the sub-valve 4 in this embodiment, but this is merely a theoretical value, and taking into consideration the above-mentioned fitting play S1, backlash S2, and backlash between the main shafts S3, etc., and other factors, the sub-valve 4 is rotated reliably the maximum amount of rotation to abut the main valve 3 against the main valve stopper 9, and the sub-valve 4 is abutted against the sub-valve stopper 31a1 of the main valve 3, so that the rotation signal is sent with a margin of 1400 pulses + α (for example, 1500 pulses) to reliably rotate the sub-valve 4 the maximum amount of rotation.

Next, the flow path switching operation by the main valve 3 and the sub-valve 4 will be described. First, as shown in FIG. 5(A), the first switching position in which the low pressure flow path 30L of the main valve 3 connects the E switching port 20E and the S port 20S, and the high pressure flow path 30H connects the D port 20D and the C switching port 20C is set as the initial state, and the setting of this state is set as the first operation a shown in FIG. 6(A) and (B). Then, the operation during the switching of the flow path is set as the second operation b shown in FIG. 7(A) and (B), and the third operation c shown in FIG. 8(A) and (B). Then, the operation to complete the switching of the flow path is set as the fourth operation d shown in FIG. 9(A) and (B). Then, the operation of rotating the drive shaft in the reverse direction by a predetermined return angle after the fourth operation d is set as the fifth operation e shown in FIG. 10(A) and (B).

Note that the names of these actions (first action a, second action b, third action c, fourth action d, fifth action e) are merely a convenient description of the order of the actions in this embodiment, and the numbers first through fifth are not used in an absolute sense. In other words, it does not exclude the addition of other actions between each action, such as the addition of another action between the first action a and the second action b.

When the first action a is performed, the initial state is reached, and as shown in FIG. 6(B), the sealing surface 42a1 of the sub-valve 4 abuts against the sub-valve seat surface 33a1 of the main valve 3, and the pressure equalizing hole 30a is closed, as shown in FIG. 6(A). In this state, the main valve 3 is pressed against the valve seat portion 20 due to the pressure difference between inside and outside.

In the second operation b, the control unit sends a pulse to the stepping motor to rotate the drive shaft in the first direction, which drives the worm 51 and the worm wheel 50, and transmits the power to the sub-valve 4 via the cam portion 50a. As a result, as shown in FIG. 7(A), the sub-valve 4 rotates in the counterclockwise direction D1, which is the left direction around the central axis 6. At this time, as described above, in the state of FIG. 6(A) and (B), the main valve 3 is pressed against the valve seat portion 20, so even if the sub-valve 4 rotates, the main valve 3 cannot rotate due to the frictional force with the valve seat portion 20, and only the sub-valve 4 rotates.

6(A) and (B), when the sub-valve 4 rotates, the sub-valve protrusion 42a slides on the main valve protrusion 33a, and the main valve protrusion 33a moves to a position between one sub-valve protrusion 42a and the other sub-valve protrusion 42a, and as shown in FIG. 7(B), the main valve protrusion 33a and the sub-valve protrusion 42a alternately mesh. At this time, the pressure equalizing hole 30a is in an open state and gradually opens. Then, the pressure equalizing hole 30a and the pressure equalizing flow path 43 overlap in the axial X direction, so that the outside of the main valve 3 communicates with the low-pressure flow path 30L through the pressure equalizing hole 30a. As a result, the pressure of the fluid on the upper side X1 outside the main valve 3 escapes into the low-pressure flow path 30L (low-pressure side). In this state, the pressure is equalized on the upper side X1 of the main valve 3 and in the low-pressure flow path 30L, so the force pressing the main valve 3 against the valve seat 20 is small, as described above, and the frictional force between the main valve 3 and the valve seat 20 is smaller than the force at which the main valve protrusion 33a and the sub-valve protrusion 42a mesh together.

As a result, as shown in FIG. 2, the main valve 3 is raised from the valve seat surface 20a to the upper side X1. In the embodiment, the main valve 3 is raised from the valve seat surface 20a to the upper side X1, but the main valve 3 does not necessarily have to be raised and may be in contact with the valve seat surface 20a. In other words, as long as the frictional force between the main valve 3 and the valve seat portion 20 is smaller than the force with which the main valve protrusion 33a and the sub-valve protrusion 42a mesh, it does not matter whether the main valve 3 is in contact with the valve seat surface 20a.

In the third operation c, the control unit further sends a pulse to the stepping motor to rotate the drive shaft in the first direction, and as shown in Figures 8 (A) and (B), the sub-valve 4 is controlled to further rotate in the counterclockwise direction D1. As described above, the second operation b causes the main valve 3 to rise above the valve seat surface 20a toward the upper X1 side, so in the third operation c, the tapered surface of the main valve protrusion 33a and the tapered surface of the sub-valve protrusion 42a come into contact with each other and become one, that is, the main valve 3 and the sub-valve 4 become one and rotate in the counterclockwise direction D1. This third operation c is performed until the main valve 3 moves to the second switching position where the low pressure flow path 30L communicates the C switching port 20C and the S port 20S, and the high pressure flow path 30H communicates the D port 20D and the E switching port 20E, as shown in Figure 5 (B), and the rotation is restricted by the main valve stopper 9.

In the fourth operation d, the control unit further sends a pulse to the stepping motor to rotate the drive shaft in the first direction, and the sub-valve 4 is further controlled to rotate in the counterclockwise direction D1. As described above, in the third operation c, the rotation of the main valve 3 around the central axis 6 is restricted, so in the fourth operation d, only the sub-valve 4 rotates in the counterclockwise direction D1. This fourth operation d is performed until the sub-valve 4 moves to a predetermined rotation position where the enlarged diameter portion 40a abuts the sub-valve stopper 31a1. It is also possible to stop the sub-valve 4 at a position where the enlarged diameter portion 40a of the sub-valve 4 does not abut the sub-valve stopper 31a1. In this case, for example, when used in an air conditioner, initialization (starting point determination) is required when the air conditioner starts operating. Therefore, it is preferable to perform the fourth operation d until the sub-valve 4 abuts the sub-valve stopper 31a1 as in this embodiment, since initialization is not required.

When only the sub-valve 4 rotates, the sub-valve protrusion 42a slides against the tapered surface of the main valve protrusion 33a, and rides up onto the main valve protrusion 33a as shown in FIG. 9(B). At this time, the seal surface 42a1 slides against the sub-valve seat surface 33a1 in accordance with the rotation of the sub-valve 4, closing the pressure equalizing hole 30a, and in a parallel state where it is in parallel contact with the sub-valve seat surface 33a1, closes the pressure equalizing hole 30a as shown in FIG. 9(A), and sets it to a closed state.

As described above, in consideration of the fit backlash S1, backlash S2, and backlash between the main shafts S3, and other factors, in order to ensure that the sub-valve 4 and the main valve 3 are in contact with each stopper (main valve stopper 9, sub-valve stopper 31a1), the control unit sends 1400 pulses + α (for example, 1500 pulses) to the stepping motor in order to rotate the sub-valve 4 by the maximum rotation amount. As a result, a rotational force of more than the maximum rotation amount is applied to the sub-valve 4, and the rotation ends with the rotation load (rotational torque) from the drive unit 5 being applied to the worm wheel 50, the sub-valve 4, and the main valve 3 in the counterclockwise direction D1. For example, a rotational torque, i.e., a residual torque, remains in the meshing portion between the worm wheel 50 and the worm 51 in the counterclockwise direction D1, and both the worm wheel 50 and the worm 51 are in a state of being subjected to surface pressure. If the rotary switching valve 100 is used in this state for a long period of time, and the worm wheel 50 is made of resin as in this embodiment, the gear portion may creep and deform, and the rotation of the worm 51 may not be transmitted. In addition, since the rotational torque also acts on the fitting structure of the auxiliary valve 4 and the worm wheel 50 (i.e., the square hole 4a and the cam portion 50a), the creep of the cam portion 50a may increase the second backlash S11, which may affect the operation of the rotary switching valve 100.

Also, as shown in FIG. 13, the rotational force of the worm 51 (a clockwise force in the figure) is applied to the sub-valve 4 and the worm wheel 50, whose rotation is restricted by the sub-valve stopper 31a1, and this causes the sub-valve 4 to be pressed in the counterclockwise direction D1 against the main valve 3. This may cause the sub-valve 4 to tilt in the axial direction X with respect to the radial direction Y. This will result in the sealing surface 42a1 being non-parallel, and the pressure equalizing hole 30a being unintentionally opened. Therefore, the fifth operation e is performed.

In the fifth operation e, as shown in Figs. 10(A) and (B), the control unit sends a pulse to the stepping motor to rotate the drive shaft in the second direction, and the drive shaft is controlled to rotate in the opposite direction to the previous operations a to d by a predetermined return angle. By this fifth operation e, as shown in Fig. 10(A), the sub-valve 4 tries to rotate in the clockwise direction D2 opposite to the counterclockwise direction D1. This reduces the rotational force applied to the sub-valve 4 and the worm wheel 50 during the fourth operation d. In addition, the fitting play S1, backlash S2, and shaft play S3 that disappeared by the fourth operation d are generated again. As a result, even if the pressure equalizing hole 30a is no longer maintained in a closed state due to the seal surface 42a1 becoming non-parallel, the seal surface 42a1 becomes parallel, and the pressure equalizing hole 30a can be closed again.

In this embodiment, as shown in FIG. 5(A), the main valve 3 is in the first switching position as the initial state. However, conversely, as shown in FIG. 5(B), when the flow path switching operation is performed from the main valve 3 in the second switching position, the low pressure flow path 30L of the main valve 3 connects the C switching port 20C to the S port 20S, and the high pressure flow path 30H connects the D port 20D to the E switching port 20E, the second switching position is the initial state. It goes without saying that the first operation a, the second operation b, the third operation c, the fourth operation d, and the fifth operation e are performed by reversing the rotation direction of the drive shaft from the above description.

Next, the specified return angle in the operation completion control of the fifth operation e will be explained in more detail. This specified return angle refers to the angle around the drive shaft of the stepping motor when rotating in the opposite direction to the first operations a to e.

The predetermined return angle is preferably set larger than the lower limit angle θ1, which is an angle based on at least one of the backlash occurring in the drive unit 5 and the backlash occurring between the central shaft 6 supporting the sub-valve 4 and the sub-valve 4. Specifically, the backlash occurring in the drive unit 5 is, for example, the above-mentioned fitting backlash S1 (first backlash S10, second backlash S11) and backlash S2. The backlash occurring between the central shaft 6 and the sub-valve 4 is, for example, the above-mentioned main shaft backlash S3. Note that the lower limit angle θ1 may be set based on, for example, the inclination of the sub-valve 4 in the axial direction X with respect to the radial direction Y when the sub-valve 4 is located at the above-mentioned predetermined rotation position (the position where the enlarged diameter portion 40a abuts against the sub-valve stopper 31a1).

Considering these, for example, if the rotation angle of the drive shaft for rotating the worm 51 by the dimension of the backlash S2 is set to the first angle A, the predetermined return angle may be set to be greater than the first angle A, which is the lower limit angle θ1. In this embodiment, the pulse for rotating the drive shaft by this first angle A is a maximum of 3 pulses, the rotation angle of the worm 51 rotating at this time is about 27°, and the rotation angle of the worm wheel 50 and the rotation angle of the auxiliary valve 4 are 0°. If the drive shaft is rotated beyond this first angle A, the drive shaft, the worm 51, and the worm wheel 50 can be rotated in the reverse direction, and the rotation torque transmitted from the worm 51 to the worm wheel 50 and the auxiliary valve 4 disappears. And, although the auxiliary valve 4 cannot be rotated in the reverse direction, because play occurs in each part including the fitting play S1, the inclination of the auxiliary valve 4 in the axial direction X with respect to the radial direction Y is often eliminated. In contrast, if the lower limit angle θ1 is set to be equal to or less than the first angle A, the worm wheel 50 cannot be rotated in reverse, and the rotational torque transmitted from the worm 51 to the worm wheel 50 and the sub-valve 4 does not disappear, so the above-mentioned tilt often cannot be eliminated.

For example, when the angle for rotating the worm wheel 50 by the dimension of the second backlash S11 is set as the third angle B, it is more preferable to set the predetermined return angle larger than the angle (A+B) obtained by adding the above-mentioned first angle A to the third angle B as the lower limit angle θ1. In this embodiment, the pulse for rotating the drive shaft by the angle (A+B) obtained by adding the first angle A to the third angle B is 25 pulses, and the rotation angle of the worm 51 rotating at this time is about 230°, the rotation angle of the worm wheel 50 is about 3.6°, and the rotation angle of the sub-valve 4 is 0°. When this angle (A+B) is set as the lower limit angle θ1 and the drive shaft is rotated beyond this angle (A+B), the sub-valve 4 can be rotated in the reverse direction in addition to the drive shaft, worm 51, and worm wheel 50, so that in combination with the effect of setting the lower limit angle θ1 to the first angle A, the inclination of the sub-valve 4 can be more easily eliminated.

When the sum of the first angle A and the third angle B (A+B) is set as the lower limit angle θ1, the tilt of the auxiliary valve 4 is often eliminated as described above. However, when there is variation in the dimensions of the backlash S2 and the second backlash S11, or when the backlash S3 between the main shafts and the first backlash S10 are also taken into consideration, the angle (A+B) alone may not be enough to eliminate the tilt of the auxiliary valve 4. For this reason, it is more preferable to set the margin angle, which is the rotation angle of the drive shaft to completely eliminate the tilt of the auxiliary valve 4 located at a predetermined rotation position, as the fourth angle C, and set the angle (A+B+C) obtained by adding the first angle A and the third angle B to the fourth angle C as the lower limit angle θ1, and set the predetermined return angle to a value greater than this.

In this case, the fourth angle C may be set to an angle greater than 1/2 of the third angle B to allow for some leeway. In this case, in this embodiment, the pulses for rotating the drive shaft by the angle (A+B+C) obtained by adding the first angle A and the third angle B to the fourth angle C are, for example, 40 pulses, and the rotation angle of the worm 51 rotating at this time is approximately 360°, the rotation angle of the worm wheel 50 is approximately 5.8°, and the rotation angle of the sub-valve 4 is approximately 2.2°.

In either case, it is more preferable to set the total angle (A+B+C) of the first angle A, third angle B, and fourth angle C to an angle that can return the sealing surface 42a1, which is in a non-parallel state as described above, to a parallel state. In other words, it is preferable that the total angle (A+B+C) of the first angle A, third angle B, and fourth angle C is set to the lower limit angle θ1, and when the drive shaft is rotated in the reverse direction as described above to a value greater than this lower limit angle θ1, the sealing surface 42a1 returns from a non-parallel state to a parallel state relative to the auxiliary valve seat surface 33a1.

In this way, by rotating the drive shaft greater than the lower limit angle θ1 in the fifth operation e, the sub-valve 4 rotates in the opposite direction to the first operation a to the fourth operation d, as shown in FIG. 11 (A).

On the other hand, it is preferable that the predetermined return angle is not simply set to be greater than the lower limit angle θ1, but also set to be smaller than the upper limit angle θ2, which is an angle based on the rotational positions of the pressure equalizing hole 30a and the sub-valve 4. Specifically, the rotational position of the pressure equalizing hole 30a and the sub-valve 4 is the closed maintenance limit position (the rotational position of the sub-valve 4 at which the closed state in which the pressure equalizing hole 30a is closed is maintained), which is defined in the above explanation as "the position of the sub-valve 4 at which the edge of the seal surface 42a1 in the state in which the pressure equalizing hole 30a is closed overlaps with the opening edge of the pressure equalizing hole 30a when the sub-valve 4, which closes the pressure equalizing hole 30a, moves in the sliding contact direction."

For example, if the rotation angle of the drive shaft for moving the sub-valve 4 to the closed maintenance limit position is set to the second angle D (the angle set based on the rotation position of the sub-valve 4 at which the closed state in which the pressure equalizing hole 30a is closed by the sub-valve 4 is maintained), the predetermined return angle may be set smaller than the second angle D as the upper limit angle θ2. In this embodiment, the pulses for rotating the drive shaft by this second angle D are 130 pulses, the rotation angle of the worm 51 rotating at this time is about 1200°, the rotation angle of the worm wheel 50 is about 20°, and the rotation angle of the sub-valve 4 is about 16°. In this way, the rotational position of the sub-valve 4, which is the basis for setting the second angle D, may be the closed maintenance limit position, and by rotating the drive shaft by the upper limit angle θ2 in the fifth operation e, as shown in FIG. 11(B), the rotation of the sub-valve 4 stops at a position where the right edge of one sub-valve protrusion 42a in the figure overlaps with the right edge of the pressure equalizing hole 30a in the figure.

Here, as described above, the upper limit angle θ2 of the second angle D is an angle based on the closed limit position, and it is described that it is preferable to set this angle smaller than the upper limit angle θ2. However, it is more preferable to set this angle to a smaller angle with a margin than the angle based on the closed limit position. The reason for this is that at the angle based on the closed limit position, there are places where the sealing surface 42a1 of the pressure equalizing hole 30a is very small, and there is a risk that the pressure equalizing hole 30a will open unintentionally due to various dimensional variations in the components that make up the rotary switching valve 100, vibrations, and other conditions, resulting in fluid leakage.

Next, a refrigeration cycle system using the rotary switching valve 100 as a flow path switching valve will be described. Figure 16 is a diagram showing an embodiment of a refrigeration cycle system, and is an example of a refrigeration cycle system for an air conditioner. The air conditioner has a compressor P, an outdoor heat exchanger 60 (condenser or evaporator), an expansion valve 70, an indoor heat exchanger 80 (condenser or evaporator), and a rotary switching valve 100 as a flow path switching valve, and each of these elements is connected by conduits as shown in the figure to form a heat pump type refrigeration cycle system.

The flow path of the refrigeration cycle system can be switched between two flow paths for cooling operation and heating operation by rotating the main valve 3 of the rotary switching valve 100 as described above. During cooling operation in FIG. 16(A), the S port 20S is connected to the E switching port 20E by the low pressure flow path 30L of the main valve 3 in the rotary switching valve 100, and the D port 20D is connected to the C switching port 20C by the high pressure flow path 30H. Then, as shown by the arrows in the figure, the refrigerant as a fluid compressed by the compressor P flows into the D port 20D of the rotary switching valve 100 and flows into the outdoor heat exchanger 60 from the C switching port 20C, and the refrigerant flowing out of the outdoor heat exchanger 60 flows into the expansion valve 70. Then, the refrigerant is expanded by this expansion valve 70 and supplied to the indoor heat exchanger 80. The refrigerant flowing out of the indoor heat exchanger 80 flows from the E switching port 20E to the S port 20S in the rotary switching valve 100, and is circulated from the S port 20S to the compressor P.

During heating operation in FIG. 16(B), in the rotary switching valve 100, the S port 20S is connected to the C switching port 20C by the low pressure flow path 30L of the main valve 3, and the D port 20D is connected to the E switching port 20E by the high pressure flow path 30H. Then, as shown by the arrows in the figure, the refrigerant compressed by the compressor P flows into the D port 20D of the rotary switching valve 100 and flows into the indoor heat exchanger 80 from the E switching port 20E, and the refrigerant flowing out of the indoor heat exchanger 80 flows into the expansion valve 70. Then, the refrigerant is expanded by this expansion valve 70 and supplied to the outdoor heat exchanger 60. The refrigerant flowing out of the outdoor heat exchanger 60 flows from the C switching port 20C to the S port 20S in the rotary switching valve 100, and is circulated from the S port 20S to the compressor P.

As described above, according to this embodiment, even if the sub-valve 4 is tilted by being pressed against the main valve 3 when the drive shaft is rotated to a predetermined rotational position where the sub-valve 4 abuts against the sub-valve stopper 31a1, the pressing force can be reduced by controlling the stepping motor (electric motor) to rotate the drive shaft in the reverse direction by a predetermined return angle, and the tilt of the sub-valve 4 can be eliminated. Therefore, leakage of fluid into the pressure equalizing hole 30a due to the tilt of the sub-valve 4 can be suppressed. In addition, the tilt of the sub-valve 4 can be suppressed from continuously applying an unexpected force to the drive unit 5. Therefore, it is possible to obtain a control method for the rotary switching valve 100 that can prevent leakage of fluid into the pressure equalizing hole 30a by suppressing the tilt of the sub-valve 4, and can prevent creep deformation by suppressing the transmission of force from the sub-valve 4 to the drive unit 5, thereby stabilizing operability.

In addition, by making the return angle of the drive shaft of the stepping motor larger than the first angle A, which is the lower limit angle θ1, and rotating the drive shaft in the reverse direction as described above by a larger angle than the lower limit angle θ1, the surface pressure acting on the meshing portion of the worm 51 and the worm wheel 50 through the auxiliary valve 4 pressed against the main valve 3 can be reduced. This makes it possible to prevent creep deformation of the worm 51 and the worm wheel 50. In addition, when the auxiliary valve 4 located at a predetermined rotation position is tilted by being pressed against the main valve 3, the tilt of the auxiliary valve 4 can often be eliminated by rotating the drive shaft in the reverse direction as described above by a larger angle than the lower limit angle θ1. Therefore, it is possible to easily prevent fluid leakage into the pressure equalizing hole 30a due to the tilt of the auxiliary valve 4. In addition, by making the upper limit angle θ2 of the return angle smaller than the second angle D, which is set based on the rotational position of the sub-valve 4 at which the pressure equalizing hole 30a is maintained in a closed state, the pressure equalizing hole 30a can be reliably maintained in a closed state even when the drive shaft is rotated in the reverse direction as described above, thereby reliably preventing fluid leakage into the pressure equalizing hole 30a.

The sum of the third angle B and the first angle A (A+B) is set to the lower limit angle θ1, and the return angle is set to an angle greater than this lower limit angle θ1. This allows the force acting on the engagement portion of the worm 51 and the worm wheel 50, as well as the force acting on the fitting structure of the worm wheel 50 and the sub-valve 4 (the square hole 41a and the cam portion 50a) via the sub-valve 4 pressed against the main valve 3, to be reduced by a greater amount than the lower limit angle θ1 by rotating the drive shaft as described above. This makes it possible to prevent creep deformation of the fitting structure of the worm 51, the worm wheel 50, and the sub-valve 4.

As described above, when the sub-valve 4 located at a predetermined rotational position is tilted due to being pressed against the main valve 3, the tilt of the sub-valve 4 may be eliminated by rotating the drive shaft in the reverse direction by a value greater than the lower limit angle θ1. However, since the lower limit angle θ1 is the third angle B plus the first angle A, the possibility of eliminating the tilt of the sub-valve 4 is increased compared to when the lower limit angle θ1 is set to the first angle A as described above. Therefore, it is easier to prevent fluid leakage into the pressure equalizing hole 30a due to the tilt of the sub-valve 4 than when the lower limit angle θ1 is set to the first angle A.

In addition, since the sum (A+B+C) of the first angle A, the third angle B, and the fourth angle C is set as the lower limit angle θ1, when the sub-valve 4 located at a predetermined rotational position is tilted by being pressed against the main valve 3, the tilt of the sub-valve 4 can be completely eliminated by rotating the drive shaft in the reverse direction as described above by a greater amount than the lower limit angle θ1. This makes it possible to more reliably prevent leakage of fluid into the pressure equalizing hole 30a due to tilt of the sub-valve 4. In addition, creep deformation of the fitting structure of the worm 51, the worm wheel 50, and the sub-valve 4 can be prevented.

In addition, even if the pressure equalizing hole 30a is unexpectedly opened by the sub-valve 4 being in a non-parallel state, the sub-valve 4 can be returned to a parallel state by rotating the drive shaft as described above by an angle greater than the total angle (A+B+C) of the first angle A, the third angle B, and the fourth angle C. Therefore, leakage of fluid into the pressure equalizing hole 30a due to tilting of the sub-valve 4 can be more reliably prevented.

In addition, according to the above embodiment, the rotational position of the auxiliary valve 4, which is the basis for setting the second angle D, which is the upper limit angle θ2 of the predetermined return angle, is the position where the edge of the seal surface 42a1 in the state where the pressure equalizing hole 30a is closed overlaps with the opening edge of the pressure equalizing hole 30a when the seal surface 42a1 that closes the pressure equalizing hole 30a moves in the sliding direction. Therefore, when the drive shaft is rotated in the reverse direction as described above, the rotation of the auxiliary valve 4 can be stopped at a position just before the edge of the seal surface 42a1 moving in the sliding direction is positioned within the opening of the pressure equalizing hole 30a (i.e., the position just before the pressure equalizing hole 30a opens), and it is possible to prevent the auxiliary valve 4 from rotating beyond this position and opening the pressure equalizing hole 30a.

Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention includes design changes within the scope of the present invention. For example, in this embodiment, three main valve protrusions 33a constituting the main valve side clutch part 33 and three sub-valve protrusions 42a constituting the sub-valve side clutch part 42 are provided, but four main valve protrusions 33a and four sub-valve protrusions 42a may be provided. In this case, the maximum rotation amount of the sub-valve 4 may be, for example, 180°, which is different from the case where three main valve protrusions 33a and three sub-valve protrusions 42a are provided. In addition, the number of main valve protrusions 33a and sub-valve protrusions 42a is not limited to four or three, and at least two of each may be provided.

Note that the return angle values in each state shown in the above embodiment vary depending on the design of the motor and gears, and the shape and backlash of each connection, and are not absolute values, but rather angle values in one embodiment and are for reference only.

Reference Signs List 1 Valve body 3 Main valve 4 Sub-valve 5 Drive section 6 Central shaft 10a Valve chamber 20 Valve seat section 20D D port (multiple ports)
20S S port (multiple ports)
20E E switching port (multiple ports)
20C C switching port (multiple ports)
30a: pressure equalizing hole 31a1: auxiliary valve stopper 100: rotary type switching valve

Claims (6)

A control method for a rotary switching valve comprising: a valve body defining a valve chamber; a valve seat portion having a plurality of ports opening into the valve chamber; a main valve provided inside the valve body to be rotatable about a central axis intersecting the valve seat portion; an auxiliary valve provided to be rotatable about the central axis and for opening and closing a pressure equalizing hole of the main valve; and a drive portion that rotationally drives the auxiliary valve,
The main valve has a sub-valve stopper that abuts against the sub-valve to stop rotation of the sub-valve,
the drive unit includes an electric motor having a drive shaft, and controls the electric motor to rotate the drive shaft to a predetermined rotation position where the sub-valve abuts against the sub-valve stopper, and then to rotate the drive shaft in the reverse direction by a predetermined return angle;
a control method for a rotary switching valve, characterized in that the return angle is set to be larger than a lower limit angle which is an angle based on at least one of the play occurring within the drive unit and the play occurring between the central shaft supporting the auxiliary valve and the auxiliary valve, and smaller than an upper limit angle which is an angle based on the rotational positions of the pressure equalizing hole and the auxiliary valve. The drive unit includes a worm that rotates with the rotation of the drive shaft, and a worm wheel that is rotatable in mesh with the worm,
the lower limit angle is a first angle that is an angle at which the worm rotates by an amount corresponding to a meshing backlash that occurs in an engagement portion between the worm and the worm wheel,
the return angle is greater than the first angle;
2. The control method for a rotary switching valve according to claim 1 , wherein the upper limit angle is a second angle that is set based on a rotational position of the sub-valve at which a closed state in which the pressure equalizing hole is closed by the sub-valve is maintained. The worm wheel and the sub-valve are connected to each other by a fitting structure capable of transmitting a rotational force therebetween,
the lower limit angle is an angle obtained by adding the first angle to a third angle, which is an angle at which the worm wheel rotates by an amount corresponding to a dimension of a second backlash, which is a backlash in a rotational direction between the worm wheel and the sub-valve in the fitting structure;
3. The method for controlling a rotary switching valve according to claim 2 , wherein the return angle is greater than an angle obtained by adding the first angle to the third angle. the lower limit angle is an angle obtained by adding the first angle and the third angle to a fourth angle, which is a margin angle for completely eliminating the inclination of the sub-valve when positioned at the predetermined rotation position,
4. The method for controlling a rotary switching valve according to claim 3 , wherein the return angle is greater than an angle obtained by adding the first angle and the third angle to the fourth angle. The main valve is provided with an auxiliary valve seat surface through which the pressure equalizing hole opens toward the auxiliary valve,
The sub-valve is provided with a seal surface that closes the pressure equalizing hole in a parallel state in contact with the sub-valve valve seat surface,
5. The control method for a rotary switching valve according to claim 4, wherein a total angle of the first angle, the third angle, and the fourth angle is a rotation angle of the drive shaft at which the seal surface returns to the parallel state from the non-parallel state relative to the auxiliary valve seat surface when the electric motor is controlled to reversely rotate the drive shaft by the predetermined return angle. The main valve is provided with an auxiliary valve seat surface through which the pressure equalizing hole opens toward the auxiliary valve,
the sub-valve is provided with a sealing surface set to be equal to or larger than the area of a portion surrounded by an opening edge of the pressure equalizing hole,
the seal surface is provided to open and close the pressure equalizing hole while being in sliding contact with the auxiliary valve seat surface in accordance with rotation of the auxiliary valve,
A control method for a rotary switching valve as described in any one of claims 2 to 5, characterized in that the rotational position of the sub-valve, which is the basis for setting the second angle, is a position where, when the sealing surface closing the pressure equalizing hole moves in a sliding contact direction, the edge of the sealing surface in a state where the pressure equalizing hole is closed overlaps with the opening edge of the pressure equalizing hole.

Images