Electric valve

Abstract

To provide an electric valve which can prevent an unintended backflow.SOLUTION: An electric valve in one aspect includes: an operation member 42 coaxially connected to a rotor 60 while being connected to a valve body 32 so as to be relatively displaceable in an axial direction, the operation member 42 having an engagement part 45 to engage with the valve body 32 at an operation limit in a valve-closing direction; a screw feeding mechanism 54 for converting a rotational motion of the rotor 60 into a translational motion of the operation member 42; an operation connection mechanism operably connecting the valve body 32 with the operation member 42 in an integrally displaceable manner when an amount of displacement from the operation limit of the operation member 42 in a valve-opening direction has reached a predefined value or more; a guide member 46 provided integrally with the body 24; and a restriction structure for restricting rotation of the operation member 42 with respect to the rotor 60. The screw feeding mechanism 54 is achieved by: a first screw 50 of the guide member 46; and a second screw 52 of the operation member 42. In a valve-closed state with the operation member 42 at the operation limit, the screw feeding mechanism 54 is locked to maintain the valve-closed state.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a motor-operated valve, and more particularly to a backflow prevention structure for a motor-operated valve. [Background technology]

[0002] Automotive air conditioning systems generally include a refrigeration cycle that includes a compressor, an external heat exchanger, an expansion device, an evaporator, and other components. The refrigeration cycle includes various control valves, such as an expansion valve, that control the flow of refrigerant. With the recent spread of electric vehicles and the like, electrically operated valves equipped with a motor as a drive unit have been widely adopted (see, for example, Patent Document 1).

[0003] The motor-operated valve of Patent Document 1 is a composite valve having a large-diameter valve (referred to as the "large-diameter valve") and a small-diameter valve (referred to as the "small-diameter valve"), and one of the valves is driven to open or close depending on the operating state of the refrigeration cycle. In this motor-operated valve, a valve hole for the small-diameter valve is provided in the valve element (first valve element) of the large-diameter valve. A shaft is connected to the rotor of the motor, and a valve element (second valve element) for the small-diameter valve is provided at the tip of the shaft. The rotational motion of the rotor is converted into translational motion of the shaft, thereby driving the second valve element in the opening or closing direction of the small-diameter valve.

[0004] The first valve body is normally kept closed by being biased by a spring, but when the lift amount of the second valve body reaches a predetermined value or more, it is operatively connected to the shaft and pulled up in the valve opening direction. To reduce the load on the motor when pulling up the first valve body, a back pressure chamber is provided for the first valve body, and a pressure-receiving structure (also called a "back pressure cancellation structure") is adopted that cancels the refrigerant pressure acting on the first valve body.

[0005] In this type of motor-operated valve, the diameter of the small-diameter valve is negligibly smaller than that of the large-diameter valve. Therefore, if the large-diameter valve opens while controlling the small-diameter valve, the control effectively ceases to function. Therefore, this motor-operated valve employs a backpressure cancellation structure that cancels most of the refrigerant pressure acting on the first valve body while still allowing some pressure to act in the valve closing direction. This structure more stably maintains the closed state of the large-diameter valve. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 7113537 Summary of the Invention [Problem to be solved by the invention]

[0007] However, such motor-operated valves can suffer from adverse effects due to the pressure-receiving structure when back pressure acts on the valve section due to a system malfunction or switching of the refrigeration cycle flow path. Specifically, refrigerant pressure acts on the first valve element in the valve opening direction, causing the first valve element to push up the second valve element. As a result, the large-diameter valve may open unintentionally, potentially causing a refrigerant leak (backflow of refrigerant). This backflow problem due to back pressure can occur not only in the combined valve described above, but also in any motor-operated valve that has a structure in which an actuating member such as a shaft and the valve element can be operatively connected or disconnected, i.e., any motor-operated valve that is driven in the valve opening direction by operative connection between the actuating member and the valve element.

[0008] An object of the present invention is to provide a motor-operated valve that can prevent unintentional backflow. [Means for solving the problem]

[0009] A motor-operated valve according to one embodiment of the present invention comprises a body having a first port, a second port, a valve hole provided in a passage connecting the first port and the second port, and a valve seat provided at an open end of the valve hole, a valve element that is detachably attached to the valve seat to open and close a valve portion, a motor including a rotor for driving the valve element in the opening and closing directions of the valve portion, an actuating member that is coaxially connected to the rotor and axially displaceable relative to the valve element and has an engaging portion that engages with the valve element at its actuation limit in the valve closing direction, a screw feed mechanism that converts rotational motion of the rotor into translational motion of the actuating member, an actuating connection mechanism that operatively connects the valve element to the actuating member so as to be displaceable together with it when the displacement of the actuating member from its actuation limit in the valve opening direction exceeds a predetermined value, a guide member that is integral with the body, and a restriction structure that restricts rotation of the actuating member relative to the rotor. The screw feed mechanism is realized by a first screw provided in the guide member and a second screw provided in the actuating member. When the operating member reaches its operating limit and enters a closed valve state, the screw feed mechanism locks, maintaining the closed valve state.

[0010] According to this embodiment, the actuating member has a second screw. In other words, the displacement of the actuating member relative to the second screw is restricted. Therefore, when the screw feed mechanism locks at the limit point of the actuating member, the actuating member also stops moving. Therefore, even if back pressure acts on the valve disc, the valve disc can be maintained in a closed state. In other words, once the actuating member reaches its limit point, the valve disc can be prevented from displacing unless the rotor is driven in the valve opening direction, preventing unintended backflow. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a motor-operated valve capable of preventing unintended backflow. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view illustrating a motor-operated valve according to a first embodiment. [Figure 2] FIG. 2 is an enlarged view of part A in FIG. [Figure 3] FIG. 2 is a diagram illustrating the normal operation of the motor-operated valve. [Figure 4] 10A and 10B are diagrams illustrating other operations of the motor-operated valve. [Figure 5] FIG. 6 is a cross-sectional view showing a motor-operated valve according to a second embodiment. [Figure 6] FIG. 6 is an enlarged view of part A in FIG. 5. [Figure 7] FIG. 10 is a cross-sectional view showing a motor-operated valve according to a third embodiment. [Figure 8] FIG. 8 is an enlarged view of part A in FIG. 7. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. For convenience, the following description may refer to the positional relationship of each structure based on the illustrated state. In the following embodiments and their modifications, substantially identical components will be designated by the same reference numerals, and their description will be omitted where appropriate.

[0014] [First embodiment] FIG. 1 is a cross-sectional view showing the motor-operated valve according to the first embodiment. The motor-operated valve 1 is applied to the refrigeration cycle of an automotive air conditioner (not shown). The refrigeration cycle is equipped with a compressor, an external heat exchanger, an expansion valve, an evaporator, etc., and the refrigerant circulation passage is switched depending on the operating state of the air conditioner. The high-temperature, high-pressure refrigerant compressed by the compressor is cooled by passing through the external heat exchanger. The refrigerant then adiabatically expands as it passes through the expansion valve, becoming low-temperature and low-pressure, and is then guided to the evaporator where it evaporates. The latent heat of evaporation cools the air inside the vehicle cabin.

[0015] In this embodiment, a gas cooler is provided as an external heat exchanger because carbon dioxide, which has a high operating pressure, is used as the refrigerant. When a condensable refrigerant such as HFO-1234yf is used, a condenser is provided instead of the gas cooler.

[0016] The motor-operated valve 1 is a composite valve that has a large-diameter first valve 2 (large-diameter valve) and a small-diameter second valve 4 (small-diameter valve) arranged coaxially, and these valves are driven by a common motor. The first valve 2 functions as an on-off valve, and the second valve 4 functions as an expansion valve.

[0017] The motor-operated valve 1 is configured by assembling a valve unit 6 and a passage body 8. The valve unit 6 includes a rotor unit 10 and a stator unit 12. The rotor unit 10 and the stator unit 12 are each fixed to the passage body 8. The rotor unit 10 is fastened to the passage body 8 via a screw structure. The stator unit 12 is fixed to the passage body 8 via a connecting member 14. The connecting member 14 includes a metal plate fixed to the stator unit 12 and a screw for fixing the metal plate to the passage body 8.

[0018] The passage body 8 is made of a metal such as an aluminum alloy and has a generally rectangular columnar shape. An inlet port 16 opens at the bottom of one side of the passage body 8, and an outlet port 18 opens at the top of the opposite side. A refrigerant passage 20 is formed in the passage body 8, connecting the inlet port 16 and the outlet port 18. Refrigerant from the upstream side is introduced into the refrigerant passage 20 through the inlet port 16, passes through a valve, and is then discharged downstream from the outlet port 18. A stepped circular mounting hole 22 is provided in the center of the upper half of the passage body 8, and communicates with the refrigerant passage 20. A female thread 23 is provided in the mounting hole 22. In this embodiment, the inlet port 16 corresponds to the "first port," and the outlet port 18 corresponds to the "second port."

[0019] The rotor unit 10 has a valve body 24 that houses a valve portion. In this embodiment, the valve body 24 is made of stainless steel (hereinafter referred to as "SUS"). A valve seat member 26 is provided at the lower end of the valve body 24, and a seal ring 28 (O-ring) is attached to the outer peripheral surface of the valve seat member 26. A male thread 25 that can be threadedly engaged with the female thread 23 is formed on the outer peripheral surface of the valve body 24. When assembling the rotor unit 10 to the passage body 8, the valve body 24 is inserted into the mounting hole 22. The male thread 25 is threadedly engaged with the female thread 23, and the valve body 24 is fastened to the passage body 8. The valve body 24 and the passage body 8 can also be collectively interpreted as "the body of the motor-operated valve 1."

[0020] A two-stage seal ring 30 (O-ring) is fitted to the outer peripheral surface of the upper part of the valve body 24 (slightly above the male thread 25). By interposing the seal ring 30 between the mounting hole 22 and the valve body 24, leakage of refrigerant from the inside of the passage body 8 to the outside and intrusion of moisture and the like from the external atmosphere into the inside of the passage body 8 and, ultimately, into the inside of the valve unit 6 are prevented.

[0021] A first valve element 32 is housed in the lower half of the valve body 24 and is supported so as to be slidable in the axial direction. A first valve hole 34 is formed inside the valve seat member 26 and is coaxial with the mounting hole 22. A first valve seat 36 is formed at the downstream open end of the first valve hole 34. The first valve element 32 is attached to and detached from the first valve seat 36 to open and close the first valve 2.

[0022] An internal passage is formed in the first valve element 32, and a second valve hole 38 is formed in the middle of the internal passage. A second valve seat 40 is formed at the upstream open end of the second valve hole 38. An actuation rod 42 extending from the rotor 60 of the rotor unit 10 is inserted into the interior of the valve body 24. The lower part of the actuation rod 42 is inserted coaxially into the first valve element 32. The actuation rod 42 is obtained by cutting a rod made of a non-magnetic metal, and a needle-shaped second valve element 44 is integrally formed at the lower part. The second valve element 44 opens and closes the second valve 4 by being attached to and detached from the second valve seat 40 from the upstream side. That is, the second valve element 44 is provided so as to be displaceable integrally with the actuation rod 42, and moves toward or away from the second valve hole 38 from the side opposite the first valve hole 34, and opens and closes the second valve 4 by being attached to and detached from the second valve seat 40.

[0023] In this embodiment, the actuating rod 42 functions as an “actuating member.” The second valve body 44 functions as an engaging portion 45 that is engaged with the first valve body 32 by being seated on (engaged with) the second valve seat 40 when the first valve 2 is in the closed state (details will be described later).

[0024] A guide member 46 that slidably supports the operating rod 42 is erected at the center of the upper part of the valve body 24. The lower end of the guide member 46 has a large diameter, and a large-diameter portion 48 of this guide member 46 is press-fitted into the center of the upper part of the valve body 24 and fixed coaxially. An internal thread 50 is provided on the inner peripheral surface of the guide member 46 to rotatably and slidably support the operating rod 42.

[0025] The actuation rod 42 is a stepped cylindrical member, and an external thread 52 is formed on the outer peripheral surface of the upper half thereof, which meshes with an internal thread 50 of the guide member 46. In this embodiment, the internal thread 50 functions as a "first screw," and the external thread 52 functions as a "second screw." A screw feed mechanism 54 using these screws converts the rotational motion of the rotor 60 into translational motion (axial motion) of the actuation rod 42. This causes the second valve body 44 to move (raise and lower) in the axial direction, i.e., in the opening and closing direction of the valve portion.

[0026] Meanwhile, the rotor 60 of the rotor unit 10 and the stator 62 of the stator unit 12 constitute a two-phase stepping motor. The rotor unit 10 has a cylindrical can 64 with a bottom, and the rotor 60 is disposed inside the can 64. The stator 62 is disposed outside the can 64. The can 64 is a cylindrical member with a bottom that covers the space in which the second valve body 44 and its drive mechanism are disposed and that contains the rotor 60, and defines an inner pressure space (internal space) where the pressure of the refrigerant acts and an outer non-pressure space (external space) where the pressure of the refrigerant does not act.

[0027] The rotor 60 includes a stepped cylindrical rotor core 66 coaxially mounted on the upper part of the actuation rod 42, a rotor magnet 68 coaxially mounted on the outer circumferential surface of the rotor core 66, and a sensor magnet 70 provided on the upper end surface of the rotor core 66. The rotor magnet 68 is cylindrical, and its upper end is fixed so as to fit into the outer circumferential surface of the rotor core 66. With this configuration, a relatively large annular space S is formed between the inner circumferential surface of the rotor magnet 68 and the outer circumferential surface of the actuation rod 42.

[0028] The sensor magnet 70 has an annular shape and is coaxially attached to the rotor core 66. The rotor magnet 68 is magnetized (magnetized) with multiple poles in the circumferential direction. The sensor magnet 70 is also magnetized (magnetized) with multiple poles.

[0029] The stator 62 is configured by assembling a bobbin 74 around which the coil 72 is wound to a yoke 76 having a plurality of pole teeth. The stator 62 is provided integrally with a case 78 of the stator unit 12. That is, the case 78 is obtained by injection molding (also called "insert molding" or "mold molding") of a corrosion-resistant resin material. The stator 62 is covered with the molded resin obtained by the injection molding. The stator unit 12 is a molded product of the stator 62 and the case 78.

[0030] The stator unit 12 has a hollow structure and is assembled to the passage body 8 with the can 64 coaxially inserted therethrough. A seal ring 80 (O-ring) is fitted onto the outer peripheral surface of the upper part of the valve body 24. By interposing the seal ring 80 between the valve body 24 and the case 78, the external atmosphere (water, etc.) is prevented from entering the gap between the can 64 and the stator 62.

[0031] The stator unit 12 has a circuit board 82 on the outside of the can 64. The circuit board 82 is fixed inside the case 78. Various circuits that function as a control unit and a communication unit are mounted on the underside of the circuit board 82. Specifically, a drive circuit for driving the motor, a control circuit (microcomputer) that outputs control signals to the drive circuit, a communication circuit for the control circuit to communicate with an external device, a power supply circuit for supplying power to each circuit and the motor (coil 72), etc. are mounted on the circuit board 82. The upper end of the case 78 is closed by a lid 84. The circuit board 82 is disposed in the space below the lid 84 of the case 78.

[0032] A magnetic sensor 85 is provided on the surface of the circuit board 82 facing the sensor magnet 70. The magnetic sensor 85 faces the sensor magnet 70 in the axial direction via the bottom end wall of the can 64. The magnetic flux generated by the sensor magnet 70 changes as the rotor 60 rotates. The magnetic sensor 85 detects the amount of displacement of the rotor 60 (the rotation angle of the rotor 60 in this embodiment) by detecting this change in magnetic flux. The control unit calculates the axial position of the second valve body 44 and therefore the opening degree of the second valve 4 based on the amount of displacement of the rotor 60.

[0033] Terminals 86 connected to the coil 72 extend from the bobbin 74 and are connected to the circuit board 82. A power terminal, a ground terminal, and a communication terminal (collectively referred to as "connection terminals 88") extend from the circuit board 82 and are each drawn out to the outside through the side wall of the case 78. A connector portion 90 is integrally provided on the side of the case 78, and the connection terminals 88 are arranged inside the connector portion 90.

[0034] FIG. 2 is an enlarged view of part A in FIG. The valve body 24 is formed by coaxially assembling a valve housing 100, a guide member 102, and a valve seat member 26. The valve housing 100 is a stepped cylinder, and seal rings 30, 80 are fitted onto its outer circumferential surface. A male thread 25 is formed at the lower end of the valve housing 100. A guide member 46 is assembled to the center of the upper part of the valve housing 100.

[0035] The guide member 102 is obtained by applying lubrication plating to a stepped cylindrical member made of stainless steel. Known lubrication plating materials, such as nickel-phosphorus (Ni-P) containing polytetrafluoroethylene (hereinafter referred to as "PTFE"), can be used as the lubrication plating material. This type of surface treatment of the sliding surface also reduces sliding resistance.

[0036] The upper end of the guide member 102 is press-fitted into the lower end of the valve housing 100, and the upper end of the valve seat member 26 is press-fitted into the lower end of the guide member 102, thereby coaxially integrating the valve housing 100, guide member 102, and valve seat member 26. A communication hole 104 that communicates the inside and outside is provided in the side of the guide member 102. A guide hole 106 is formed by the inner circumferential surface of the upper part of the guide member 102. The guide hole 106 is provided coaxially with the first valve hole 34.

[0037] The first valve body 32 is cylindrical and has a bottom, and is slidably supported in the guide hole 106. The first valve body 32 is cylindrical and has a bottom with a sufficient thickness. A back pressure chamber 108 is formed above the first valve body 32. The back pressure chamber 108 is a space surrounded by the guide member 46, the valve housing 100, and the first valve body 32. A valve chamber 110 is formed inside the first valve body 32 (above the bottom). A stepped disc-shaped operating connecting member 112 is coaxially inserted and fixed to the top of the first valve body 32.

[0038] The actuation connecting member 112 has an insertion hole 114 in the center of its bottom. The actuation rod 42 passes coaxially through the insertion hole 114. The actuation connecting member 112 is provided with a plurality of communication holes 116 that communicate between the inside and outside of the first valve body 32. The communication holes 116 communicate between the valve chamber 110 and the back pressure chamber 108. The actuation connecting member 112 is fixed to the first valve body 32 by fitting its upper end opening into the upper end opening of the first valve body 32 and caulking the protrusion on the periphery of the upper end opening of the first valve body 32 inward.

[0039] An annular seal receiving portion 120 that opens radially inward is formed between the valve housing 100 and the guide member 102. Double seal rings 122, 124 are fitted into the seal receiving portion 120. The seal ring 122 is an O-ring with a circular cross section, and the seal ring 124 is a square ring with a rectangular cross section. The seal ring 124 is disposed so as to be inscribed within the seal ring 122. The outer peripheral surface of the seal ring 122 is in close contact with the inner peripheral surface of the valve housing 100 and the upper end surface of the guide member 102, and the inner peripheral surface of the seal ring 124 is in close contact with the outer peripheral surface of the first valve body 32.

[0040] The seal ring 124 is made of PTFE, has high lubrication performance and appropriate elasticity (flexibility), and slidably supports the first valve body 32. In this embodiment, the seal ring 124 has an inner diameter slightly smaller than that of the guide hole 106 and primarily supports the first valve body 32. The guide hole 106 has an inner diameter slightly larger than that of the first valve body 32 and suppresses axial wobble of the first valve body 32. The seal ring 124 prevents or suppresses refrigerant leakage through the clearance between the guide member 102 and the first valve body 32.

[0041] A spring 126 (functioning as a "first biasing member") that biases the first valve body 32 in the valve closing direction is interposed between the valve housing 100 and the first valve body 32. A spring 128 (functioning as a "second biasing member") that biases the second valve body 44 in the valve closing direction is interposed between the guide member 46 and the operating rod 42.

[0042] A radially protruding locking portion 129 is provided on the actuation rod 42 slightly above the second valve body 44. The locking portion 129 is formed, for example, of an E-ring. By hooking this locking portion 129 onto the first valve body 32 (the actuation connecting member 112), the first valve body 32 can be pulled up in the valve-opening direction against the biasing force of the spring 126. A mechanism that operatively connects the first valve body 32 and the actuation rod 42 (i.e., the second valve body 44) in this way so that they can be displaced together is called an "actuation connecting mechanism."

[0043] The operating connection member 112 also functions as a spring bearing that supports the spring 126. The biasing force of the spring 126 is transmitted to the first valve body 32 via the operating connection member 112. Furthermore, when the second valve body 44 is opened, the locking portion 129 is displaced relative to the first valve body 32 and comes into contact with the bottom surface of the operating connection member 112, pushing it up, thereby operating the first valve body 32 in the valve opening direction.

[0044] The can 64 is made of the same type of non-magnetic metal (SUS in this embodiment) as the valve housing 100, and is assembled coaxially with its lower part fitted onto the upper end of the valve housing 100. The valve body 24 and the can 64 are fixed and sealed together by applying a full-circumference weld (not shown) along the boundary between the lower end of the can 64 and the valve housing 100. The space surrounded by the valve body 24 and the can 64 forms the above-mentioned pressure space.

[0045] By making the guide member 102 a separate component from the valve housing 100, the welded part (valve housing 100) and the lubricant-coated part (guide member 102) can be produced separately. This simplifies the manufacturing process, as it is sufficient to simply immerse the entire guide member 102 material in a plating solution, without having to take the time to paint or vapor-deposit a plating film on the guide hole 106.

[0046] A plurality of communication holes 130 (small holes) are provided through the bottom of the first valve body 32 in a direction parallel to the axis (only one is shown in the figure). The lower end openings of these communication holes 130 serve as inlet ports 132. The communication holes 130 communicate between the upstream side of the first valve seat 36 in the first valve hole 34 and the valve chest 110. The communication holes 130, the valve chest 110, and the communication hole 116 form a "communication passage" that communicates between the upstream side of the first valve seat 36 and the back pressure chamber 108. This communication passage communicates between the valve chest 110 and the first valve hole 34 at a position different from that of the second valve hole 38.

[0047] A downstream passage 134 extending perpendicular to the axis is provided at the bottom of the first valve body 32. The downstream passage 134 has an outlet port 136 that opens toward the outlet port 18. In this embodiment, the inlet port 132 corresponds to the "third port," and the outlet port 136 corresponds to the "fourth port."

[0048] The second valve hole 38 communicates between the valve chamber 110 and the downstream passage 134. The communication hole 130 is disposed so as not to intersect with the downstream passage 134. The flow path cross section of the downstream passage 134 is sufficiently larger than the flow path cross section of the communication hole 130. The multiple communication holes 130, the valve chamber 110, the second valve hole 38, and the downstream passage 134 form an internal passage of the first valve body 32. The tip of the second valve body 44 passes through the second valve hole 38, and is attached to and detached from the second valve seat 40 by its tapered surface.

[0049] When the first valve 2 is closed or slightly opened as shown in the figure, the pressure on the upstream side of the first valve seat 36 (upstream pressure P1) is higher than the pressure on the downstream side of the first valve seat 36 (downstream pressure P2). Meanwhile, because the back pressure chamber 108 communicates with the upstream side of the first valve seat 36 via the valve chamber 110 and the communication hole 130, the pressure in the back pressure chamber 108 (also referred to as "back pressure") is approximately equal to the upstream pressure P1. As a result, the fluid pressure acting on the first valve body 32 is almost canceled out.

[0050] In this embodiment, to improve the valve closing performance of the first valve 2, the effective pressure-receiving diameter d1 of the sliding portion of the first valve element 32 is slightly larger than the seal portion diameter d2 of the detachable portion of the first valve element 32 (d1 > d2). The effective pressure-receiving diameter d1 is the outer diameter of the sliding portion of the first valve element 32 relative to the guide hole 106 or the seal ring 124. The seal portion diameter d2 is the outer diameter of the portion of the first valve element 32 where it is detachable from the first valve seat 36. However, because the difference in diameter is minimal, as described above, the fluid pressure acting on the first valve element 32 is almost canceled out. This reduces the resistance when the first valve element 32 is pulled in the valve opening direction, and reduces the rotational torque (rotational driving force) of the motor required to open the first valve 2. This pressure-receiving structure of the first valve element 32 is called a "back pressure cancellation structure."

[0051] Meanwhile, a pressure difference (P1-P2) between the upstream pressure P1 and the downstream pressure P2 occurs in the gap between the first valve body 32 and the guide hole 106. In this regard, in this embodiment, the seal rings 122 and 124 are provided to prevent refrigerant from leaking through the gap.

[0052] The upper portion of the actuation rod 42 is provided with a notch 140 (a so-called H-cut structure) having a pair of surfaces parallel to the axis. Meanwhile, an insertion hole of a shape complementary to the notch 140 is provided along the axis of the rotor core 66, and the notch 140 is inserted and fitted into the notch 140. A push nut 142 is press-fitted into the upper end of the actuation rod 42, preventing the actuation rod 42 from separating from the rotor core 66. In this manner, the actuation rod 42 and the rotor core 66 are coaxially assembled. The fitting structure between the notch 140 and the insertion hole provides a "restriction structure" that restricts rotation of the actuation rod 42 relative to the rotor 60. The actuation rod 42 functions as a rotation shaft of the rotor 60. While the embodiment employs an H-cut structure as the restriction structure, a D-cut structure or other anti-rotation structure may also be employed.

[0053] Next, the operation of the motor-operated valve 1 will be described. Figure 3 shows the normal operation of the motor-operated valve 1. Figure 3(A) shows the first valve 2 and the second valve 4 in a closed state. Figure 3(B) shows the first valve 2 in a closed state and the second valve 4 in an open state (controlled state). Figure 3(C) shows the first valve 2 and the second valve 4 in an open state.

[0054] When the system is operating normally, the upstream pressure P1 is higher than the downstream pressure P2 (P1 > P2). Therefore, when the motor is driven to rotate the rotor 60 in the normal direction and move the actuating rod 42 upward, the actuating rod 42 is displaced axially relative to the first valve body 32, and the engaging portion 45 moves away from the first valve body 32. In other words, the second valve body 44 moves away from the second valve seat 40, opening the second valve 4 (FIGS. 3A and 3B). At this time, the communication hole 130, the valve chamber 110, the second valve hole 38, and the downstream passage 134 communicate with each other. Refrigerant from the upstream side flows through the internal passage of the first valve body 32, passes through the second valve body 4, and is discharged downstream. In other words, a forward flow state is established, in which the refrigerant flows from the inlet port 16 to the outlet port 18. Adjusting the second valve body 4 to a predetermined opening allows it to function as an expansion valve.

[0055] When the actuation rod 42 is further actuated in the valve opening direction, and the displacement of the actuation rod 42 from the closed state of the second valve 4 reaches or exceeds a predetermined value, the locking portion 129 engages with the actuation connecting member 112, and the actuation rod 42 and the first valve body 32 are operatively connected (FIG. 3(C)). The actuation rod 42 then pulls up the first valve body 32 against the biasing force of the spring 126. This causes the first valve body 32 to separate from the first valve seat 36, and the first valve 2 opens. The refrigerant flows downstream via both the first valve 2 and the second valve 4. At this time, a large flow rate of refrigerant can be allowed to flow, but the flow rate can be adjusted by adjusting the opening of the first valve 2.

[0056] On the other hand, when the motor is driven to rotate the rotor 60 in the reverse direction, the actuating rod 42 moves downward. At this time, the first valve body 32 moves in the valve closing direction while maintaining the operative connection with the actuating rod 42 due to the biasing force of the spring 126. First, the first valve body 32 seats on the first valve seat 36, and the first valve 2 enters the valve closed state. When the actuating rod 42 is further actuated in the valve closing direction, the locking portion 129 disengages from the operative connection member 112, and the operative connection between the actuating rod 42 and the first valve body 32 is released. Thereafter, the second valve body 44 seats on the second valve seat 40, and the second valve 4 enters the valve closed state.

[0057] 4A to 4C are diagrams showing other operations of the motor-operated valve 1. Figures 4A to 4C show the operation process of each valve. As described above, in this embodiment, the rotor 60 is fixed integrally to the actuation rod 42. On the other hand, when the first valve 2 and the second valve 4 are both closed, the first valve body 32 is engaged with the first valve seat 36, and the second valve body 44 is engaged with the second valve seat 40 (FIG. 4(A)). At this time, the screw feed mechanism 54 is locked when the actuation rod 42 reaches its limit of movement in the valve closing direction. Because the male thread 52 of the actuation rod 42 constitutes the screw feed mechanism 54, locking the screw feed mechanism 54 also locks the displacement of the second valve body 44 (engagement portion 45), which is integral with the actuation rod 42. This locked state is maintained as long as the motor is stopped.

[0058] Therefore, even if a back pressure that induces backflow is applied to the system for some reason (P2>P1), the first valve 2 and the second valve 4 remain closed as long as the motor is stopped (FIG. 4(A)). That is, although the back pressure causes refrigerant pressure in the valve opening direction to act on the first valve body 32, the engagement portion 45 remains engaged with the first valve body 32 with its displacement restricted. That is, the second valve body 44 remains seated on the second valve seat 40, locking the first valve body 32 from above. This prevents the first valve 2 and the second valve 4 from opening, preventing unintended backflow.

[0059] Furthermore, in systems requiring bidirectional flow, the configuration of this embodiment can actively control the reverse flow of refrigerant. Specifically, the opening of the first valve 2 in response to the reverse flow can be controlled by driving the motor to control the displacement of the actuating rod 42 ( FIG. 4B ). At this time, the engaging portion 45 maintains its engagement with the first valve element 32. That is, the second valve element 44 maintains its seated position on the second valve seat 40, supporting the first valve element 32 from above and stabilizing the opening of the first valve 2. The opening of the first valve 2 can be controlled between a closed state and a fully open state. Alternatively, the first valve 2 may simply be controlled as an on-off valve that switches between an open state and a closed state. Even when the first valve 2 is fully open, if the actuating rod 42 is still driven in the valve opening direction, the engaging portion 45 and the first valve element 32 are disengaged ( FIG. 4C ).

[0060] As described above, in this embodiment, the male thread 52 of the actuating rod 42 constitutes the screw feed mechanism 54, and when the screw feed mechanism 54 is locked, the displacement of the second valve body 44, which is integral with the actuating rod 42, is also locked. This locked state is maintained as long as the motor is stopped. In other words, as long as the rotor is not driven in the valve opening direction, the displacement of the second valve 4 can be prevented, and as a result, the displacement of the first valve 2 can also be prevented. This makes it possible to prevent unintended backflow in the motor-operated valve 1.

[0061] [Second embodiment] FIG. 5 is a cross-sectional view showing the motor-operated valve according to the second embodiment. This embodiment differs from the first embodiment in that a screw feed mechanism 54 is configured between a rotating shaft 262 provided on a rotor 260 and a guide member 246, and in that a valve seat member 226 is provided on a passage body 208.

[0062] The motor-operated valve 201 is formed by assembling a valve unit 206 and a passage body 208. The valve unit 206 includes a rotor unit 210 and a stator unit 12. A valve seat member 226 is assembled to the passage body 208 midway through the refrigerant passage 20. The valve seat member 226 is an annular member made of stainless steel, and is coaxially press-fitted into the lower end of the mounting hole 22. A first valve seat 36 is formed at the open end of the valve seat member 226. A first valve body 232 is attached to and detached from the first valve seat 36 to open and close the first valve 2.

[0063] FIG. 6 is an enlarged view of part A in FIG. The rotor unit 210 includes a valve body 224 and a rotor 260. The valve body 224 includes a valve housing 200 and a guide member 202. The valve housing 200 and the guide member 202 are not directly fixed to each other. The guide member 202 has a stepped annular shape, and its lower part is press-fitted coaxially into the center of the mounting hole 22.

[0064] The valve housing 200 is inserted into the mounting hole 22 and fastened so that it is positioned directly above the guide member 202. By screwing the valve housing 200 into the passage body 208, the guide member 202 is pressed down from above by the valve housing 200, and is stably fixed in place. The inner peripheral surface of the guide member 202 forms a guide hole 106. A seal ring 80 is fitted onto the outer peripheral surface of the upper part of the valve housing 200, and a seal ring 30 is fitted onto the outer peripheral surface of the central part.

[0065] The first valve body 232 has a structure generally similar to that of the first valve body 32 of the first embodiment, but the seal structure between the guide member 202 and the first valve body 232 is different from that of the first embodiment. That is, a seal ring 222 is fitted onto the outer peripheral surface of the upper part of the first valve body 232 to ensure sealing between the first valve body 232 and the guide member 202. In this embodiment, a double seal ring structure like that of the first embodiment is not provided. Since the effective pressure-receiving diameter d1 of the first valve body 232 is slightly larger than the seal portion diameter d2, the pressure-receiving structure of the first valve body 232 is the same as that of the first embodiment.

[0066] A guide member 246 is erected at the top center of the valve housing 200. A male thread 52 is formed on the outer peripheral surface of the axial center of the guide member 246. Meanwhile, a cylindrical rotating shaft 262 with a bottom is provided inside the rotor 260. A female thread 50 is formed on the inner peripheral surface of the rotating shaft 262. The rotating shaft 262 is fitted onto the guide member 246 with its open end facing downward. The upper end of the rotating shaft 262 is press-fitted into the rotor core 266. That is, in this embodiment, the rotating shaft 262 is provided inside the rotor core 266, and the actuating rod 242 is fixed to the rotating shaft 262. In this embodiment, the rotating shaft 262 and the actuating rod 242 constitute an "actuating member."

[0067] An insertion hole having a shape complementary to the notch 140 of the actuation rod 242 is provided at the bottom of the rotation shaft 262, and the notch 140 is inserted and fitted into the insertion hole. A push nut 142 is press-fitted into the upper end of the actuation rod 242, preventing the actuation rod 242 from separating from the rotation shaft 262. In this manner, the actuation rod 242 and the rotation shaft 262 are coaxially assembled. The fitting structure (H-cut structure) between the notch 140 and the insertion hole restricts the rotation of the actuation rod 42 relative to the rotor 60, thereby realizing a "restriction structure" that restricts the rotation of the actuation member relative to the rotor 60. A second valve body 244 is integrally provided at the lower end of the actuation rod 242.

[0068] In this embodiment as well, a female thread 50 is provided on the inner peripheral surface of a rotating shaft 262, and an actuation rod 242 is fixed to the rotating shaft 262. The female thread 50 of the rotating shaft 262 constitutes a screw feed mechanism 54, and when the screw feed mechanism 54 is locked, the displacement of the second valve body 244, which is integral with the actuation rod 242, is also locked. This locked state is maintained as long as the motor is stopped. This makes it possible to prevent unintended backflow in the motor-operated valve 201. Note that the operation of the motor-operated valve 201 is substantially the same as in the first embodiment, and therefore a description thereof will be omitted.

[0069] [Third embodiment] FIG. 7 is a cross-sectional view showing a motor-operated valve according to a third embodiment. This embodiment differs from the first embodiment in that the motor-operated valve 301 is not a combined valve but has only a large-diameter valve. The motor-operated valve 301 is configured by assembling a valve unit 306 and a passage body 8. The valve unit 306 includes a rotor unit 310 and a stator unit 12. The rotor unit 310 includes a cylindrical valve element 332 with a bottom. The valve element 332 moves toward or away from the valve seat 36 to adjust the opening degree of the valve portion 302.

[0070] FIG. 8 is an enlarged view of part A in FIG. The valve element 332 is assembled to the valve body 24 with its open end facing downward, and is slidably supported by the seal ring 124 and the guide hole 106. The open end of the valve element 332 is attached to and detached from the valve seat 36 to open and close the valve section 302.

[0071] An actuation rod 342 is provided so as to pass through the upper end of the valve body 332. An insertion hole 114 is provided in the center of the upper end of the valve body 332, and communication holes 116 are provided around it. The lower part of the actuation rod 342 is reduced in diameter, and this reduced-diameter portion 340 passes through the insertion hole 114. A tapered engagement portion 345 is formed at the base end of the reduced-diameter portion 340. A locking ring 346 is inserted into the lower half of the reduced-diameter portion 340, and a push nut 350 is press-fitted from below.

[0072] The locking ring 346 is loosely fitted into the reduced diameter portion 340 without being fixed thereto, and is supported from below by a push nut 350 to prevent it from falling off the operating rod 342. By hooking the locking ring 346 onto the bottom of the valve body 332, the valve body 332 can be pulled up in the valve opening direction against the biasing force of the spring 126. In other words, the locking ring 346 functions as a "locking portion" and activates the operating linkage mechanism. The effective pressure-receiving diameter d1 of the valve body 332 is slightly larger than the seal portion diameter d2, so the pressure-receiving structure of the valve body 332 is the same as in the first embodiment.

[0073] The rotor 360 has a non-magnetic connecting member 352 inside a rotor core 366, and an actuating rod 342 is fixed coaxially with the connecting member 352. In this embodiment, the actuating rod 342 constitutes the "actuating member."

[0074] In this embodiment as well, the male thread 52 of the actuating rod 342 constitutes the screw feed mechanism 54, and when the screw feed mechanism 54 is locked, the displacement of the engaging portion 345, which is integral with the actuating rod 342, is also locked. This locked state is maintained as long as the motor is stopped. This makes it possible to prevent unintended backflow in the motor-operated valve 301. Note that the operation of the motor-operated valve 301 is substantially the same as the operation of the second valve 4 (large-diameter valve) in the first embodiment, and therefore a description thereof will be omitted.

[0075] Although the preferred embodiment of the present invention has been described above, it goes without saying that the present invention is not limited to this specific embodiment, and various modifications are possible within the scope of the technical concept of the present invention.

[0076] [Variations] In the above embodiment, the restricting structure for restricting displacement of the actuating member relative to the rotor is an example in which the actuating member and the rotor are integrated by press-fitting. In a modified example, the actuating member and the rotor may be fastened together by a screw structure or may be fixed by welding or the like.

[0077] In the above embodiment, an example was shown in which the actuating member had a second screw. In a modified example, a configuration may be adopted in which the actuating member and the second screw are relatively displaceable within a predetermined clearance range. For example, in the second embodiment shown in FIG. 6, the actuating rod 242 may be made to be relatively displaceable within a predetermined clearance range in the axial direction with respect to the rotation shaft 262 by adjusting the press-fit position (fixed position) of the push nut 142 (restriction member) relative to the actuating rod 242 (actuating member). Even with such a configuration, if there is a relative displacement of the predetermined clearance, the screw feed mechanism is locked and the valve closed state can be maintained.

[0078] In the above embodiment, a configuration in which lubricating plating is applied to the guide member 102 has been exemplified. In a modified example, the material of the guide member 102 may not be the same SUS as the first valve body 32, but may be a different material such as brass. This can prevent wear caused by the same material.

[0079] In the above embodiment, the spring 126 is exemplified as the biasing member that biases the first valve body 32 in the valve closing direction, but rubber or other elastic bodies may also be used.

[0080] In the above embodiment, the stator includes a yoke having pole teeth. In a modified example, the stator may include a laminated core.

[0081] In the above embodiment, the stator unit 12 is a two-phase stepping motor, but it may also be configured as a three-phase stepping motor.

[0082] In the above embodiment, the small-diameter second valve is configured as an expansion valve, but it may also be configured as an on-off valve without an expansion function.

[0083] In the above embodiment, the motor-operated valve is applied to the refrigeration cycle of an automotive air conditioner, but the motor-operated valve may be applied to any air conditioner equipped with an electric expansion valve, not limited to vehicles. The motor-operated valve may also be configured as a motor-operated valve for controlling the flow of fluids other than refrigerants, such as in a hot water supply system or a hydraulic control system.

[0084] The present invention is not limited to the above-described embodiments and modifications, and the components can be modified without departing from the spirit of the invention. Various inventions can be formed by appropriately combining multiple components disclosed in the above-described embodiments and modifications. Furthermore, some components can be omitted from all the components shown in the above-described embodiments and modifications. [Explanation of symbols]

[0085] 1 Motor-operated valve, 2 First valve, 4 Second valve, 6 Valve unit, 8 Passage body, 10 Rotor unit, 12 Stator unit, 16 Inlet port, 18 Outlet port, 20 Refrigerant passage, 22 Mounting hole, 24 Valve body, 26 Valve seat member, 32 First valve body, 34 First valve hole, 36 First valve seat, 38 Second valve hole, 40 Second valve seat, 42 Actuating rod, 42 Actuating member, 44 Second valve body, 45 Engagement portion, 46 Guide member, 54 Screw feed mechanism, 60 Rotor, 62 Stator, 64 Can, 100 Valve housing, 102 Guide member, 106 Guide hole, 108 Back pressure chamber, 129 Locking portion, 132 Inlet port, 136 Outlet port, 200 Valve housing, 201 Motor-operated valve, 202 Guide member, 206 Valve unit, 208 passage body, 210 rotor unit, 224 valve body, 226 valve seat member, 232 first valve body, 242 operating rod, 244 second valve body, 246 guide member, 260 rotor, 262 rotating shaft, 301 motor-operated valve, 302 valve portion, 306 valve unit, 310 rotor unit, 332 valve body, 342 operating rod, 345 engagement portion, 346 locking ring, 360 rotor.

Claims

1. a body having a first port, a second port, a valve hole provided in a passage that connects the first port and the second port, and a valve seat provided at an open end of the valve hole; a valve body that is attached to and detached from the valve seat to open and close the valve portion; a motor including a rotor for driving the valve body in the opening and closing directions of the valve portion; an actuating member that is coaxially connected to the rotor and is connected to the valve body so as to be displaceable relative to the axial direction, and that has an engaging portion that is engaged with the valve body at an actuation limit in a valve closing direction; a screw feed mechanism that converts the rotational motion of the rotor into the translational motion of the actuating member; an operational connection mechanism that operationally connects the valve body to the operating member so as to be displaceable integrally with the operating member when a displacement amount of the operating member in a valve opening direction from the operational limit reaches a predetermined value or more; a guide member integrally provided on the body; a restricting structure that restricts rotation of the operating member relative to the rotor; Equipped with the screw feed mechanism is realized by a first screw provided in the guide member and a second screw provided in the actuation member, The motor-operated valve is characterized in that the screw feed mechanism is locked when the operating member reaches the operating limit and is in a closed state, thereby maintaining the closed state.

2. the body having a first valve hole as the valve hole and a first valve seat as the valve seat; a first valve element as the valve element, the first valve element having a third port communicating with the first port, a fourth port communicating with the second port, a second valve hole provided in a passage that communicates the third port with the fourth port, and a second valve seat provided at an open end of the second valve hole, the first valve element being detachably attached to the first valve seat to open and close the first valve; a second valve body that is provided so as to be displaceable integrally with the actuating member, that approaches or moves away from the second valve hole from the side opposite to the first valve hole, and that is attached to or detached from the second valve seat to open or close the second valve; Equipped with 2. The motor-operated valve according to claim 1, wherein the screw feed mechanism is locked by stopping the motor when the first valve and the second valve are in a closed state, thereby maintaining the first valve and the second valve in a closed state.

3. a valve chamber for accommodating the second valve body is formed inside the first valve body; a back pressure chamber communicating with the valve chamber is formed on the opposite side of the first valve body from the first valve hole, 3. The motor-operated valve according to claim 2, further comprising a communication passage for communicating between the valve chamber and the first valve hole, the communication passage being provided at a position different from the second valve hole.

4. the first port is an inlet port for introducing a fluid from the upstream side, while the second port is an outlet port for discharging a fluid to the downstream side; the body has a guide hole provided coaxially with the first valve hole, the first valve body is slidably supported in the guide hole, 4. The motor-operated valve according to claim 3, wherein an effective pressure-receiving diameter at the sliding portion of the first valve body is larger than a seal portion diameter at the detachable portion of the first valve body, so that pressure in the valve closing direction acts on the first valve body when the fluid is flowing in a forward direction.

5. 2. The motor-operated valve according to claim 1, wherein when the fluid pressure at the second port becomes higher than the fluid pressure at the first port, the engaging portion controls the open / closed state or opening degree of the valve portion while supporting the valve body.

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