Motor-operated valve

Abstract

To improve the stability of a rotor by reducing the influence, on a rotor magnet, of the magnetic field of a sensor magnet in a motor-operated valve.SOLUTION: A motor-operated valve 1 comprises: an operation rod 32 axially supporting a valve element 34; a rotor 60 operating the operation rod 32; a rotor magnet 104 having a plurality of magnetic poles disposed along the outer periphery of the rotor 60; a screw feeding mechanism 109 converting the rotary motion of the rotor 60 into the axial motion of the operation rod 32; a sensor magnet 106 provided coaxially with the rotor 60 and rotatable integrally with the rotor 60; and a magnetic sensor 119 which is provided axially opposed to the sensor magnet 106 and detects the magnetic flux of the sensor magnet 106 to thereby detect the displacement amount of the rotor 60. The axial both surfaces of the sensor magnet 106 are magnetized, each of the surfaces has a plurality of magnetic poles in the rotary direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electrically operated valve equipped with a magnetic sensor for detecting a valve opening degree. [Background technology]

[0002] Automotive air conditioners are generally configured with a compressor, a condenser, an expansion device, an evaporator, and other components arranged in a refrigeration cycle. The refrigeration cycle is provided with various control valves, such as an expansion valve as an expansion device, to control the flow of the refrigerant. With the recent spread of electric vehicles, motor-operated valves equipped with a motor as a drive unit are becoming more widely used.

[0003] Known motorized valves of this type include one equipped with a magnetic sensor for detecting the valve opening degree (see, for example, Patent Document 1). A valve disc is provided at one end of an actuating rod that rotates together with the rotor, and a magnet (sensor magnet) is provided at the other end. A magnetic sensor is provided so as to face the sensor magnet in the axial direction. The rotational motion of the rotor is converted into axial motion of the valve disc by a screw feed mechanism. By detecting changes in magnetic flux accompanying the rotation of the rotor with the magnetic sensor, the rotational angle of the sensor magnet and therefore the axial position of the valve disc can be detected, and the valve opening degree can be calculated. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-135908 A Summary of the Invention [Problem to be solved by the invention]

[0005] In such motor-operated valves, the rotor magnet (rotor magnet) and the sensor magnet are disposed relatively close to each other, so the magnetic field of the sensor magnet may interfere with the magnetic field of the rotor magnet. As a result, the balance of the attractive forces between the rotor and the stator may be lost, and stable rotation of the rotor may be hindered. Note that such problems may occur in motor-operated valves used for various purposes, not limited to refrigeration cycles.

[0006] An object of the present invention is to reduce the effect of the magnetic field of a sensor magnet on a rotor magnet in an electrically operated valve equipped with a magnetic sensor, thereby ensuring the stability of the rotor. [Means for solving the problem]

[0007] One aspect of the present invention is an electrically-operated valve. This electrically-operated valve includes an actuating rod that supports a valve body in the axial direction, a rotor that actuates the actuating rod, a rotor magnet with multiple magnetic poles along the outer circumferential surface of the rotor, a screw feed mechanism that converts the rotational motion of the rotor into the axial motion of the actuating rod, a sensor magnet that is coaxial with the rotor and can rotate integrally with the rotor, and a magnetic sensor that faces the sensor magnet in the axial direction and detects the amount of displacement of the rotor by detecting the magnetic flux of the sensor magnet. The sensor magnet is magnetized on both sides in the axial direction so that the polarities are opposite to each other, and each side has multiple magnetic poles in the rotational direction.

[0008] According to this aspect, the sensor magnet is magnetized with opposite polarities on both sides, thereby ensuring sufficient magnetic flux density in the axial direction. By magnetizing the sensor magnet with opposite polarities on both sides and having multiple magnetic poles on each side, it is possible to prevent the magnetic field of the sensor magnet from affecting the rotor magnet, as described below, and ensure rotational stability of the rotor. Effect of the Invention

[0009] According to the present invention, in an electrically operated valve equipped with a magnetic sensor, the effect of the magnetic field of the sensor magnet on the rotor magnet can be reduced, thereby ensuring rotational stability of the rotor. [Brief description of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view illustrating a motor-operated valve according to an embodiment. [Diagram 2] FIG. 2 is a diagram illustrating a configuration of a stator and its surroundings. [Diagram 3] FIG. 2 is a diagram illustrating a configuration of a rotor. [Figure 4] This is a diagram showing the effect of using a sensor magnet with four poles on both sides in two upper and lower layers. [Diagram 5] 13 is a diagram showing the results of an analysis verifying the effect of the inner diameter of a sensor magnet on the magnetic flux density detected by a magnetic sensor. [Figure 6] 13 is a diagram illustrating a configuration of a rotor according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following description, for convenience, the positional relationship of each structure may be expressed based on the illustrated state. In addition, in the following embodiment and its modified examples, substantially the same components are given the same reference numerals, and the description thereof will be omitted as appropriate.

[0012] FIG. 1 is a cross-sectional view illustrating a motor-operated valve according to an embodiment. The motor-operated valve 1 is applied to a refrigeration cycle of an automobile air conditioner (not shown). This refrigeration cycle includes a compressor that compresses the circulating refrigerant, a condenser that condenses the compressed refrigerant, an expansion valve that throttles and expands the condensed refrigerant and sends it out in the form of mist, and an evaporator that evaporates the mist of refrigerant and cools the air inside the vehicle cabin with the latent heat of evaporation. The motor-operated valve 1 functions as an expansion valve for the refrigeration cycle.

[0013] The motor-operated valve 1 is constructed by assembling a valve body 2 and a motor unit 3. The valve body 2 has a body 5 that houses a valve portion. The body 5 functions as a "valve body." The body 5 is constructed by assembling a first body 6 and a second body 8 coaxially. Both the first body 6 and the second body 8 are made of stainless steel (hereinafter referred to as "SUS"). Since the second body 8 is provided with a valve seat 24, a material with excellent wear resistance is selected. The first body 6 has better weldability than the second body 8, and the second body 8 has better workability than the first body 6.

[0014] The first body 6 is a stepped cylinder whose outer diameter tapers stepwise downward. The outer diameter of the upper end of the first body 6 is slightly tapered, forming a locking portion 52 with a step. A male thread 10 is formed on the outer peripheral surface of the lower part of the first body 6 for assembling the motor-operated valve 1 to a piping body (not shown). The piping body is connected to piping extending from the condenser side and piping connected to the evaporator, but the details thereof will not be described. A seal receiving portion 12 consisting of an annular groove is formed on the outer peripheral surface of the first body 6 slightly above the male thread 10, and a seal ring 14 (O-ring) is fitted into it.

[0015] The first body 6 has a circular hole-shaped recessed fitting portion 16 at its lower portion. The second body 8 has a bottomed cylindrical shape, and its upper portion is press-fitted into the recessed fitting portion 16. A seal accommodating portion 18 consisting of an annular groove is formed on the outer peripheral surface of the lower portion of the second body 8, and a seal ring 20 is fitted into the seal accommodating portion 18. A valve hole 22 is provided so as to penetrate the bottom portion of the second body 8 in the axial direction, and a valve seat 24 is formed at the upper end opening of the valve hole 22. An inlet port 26 is provided at the side of the second body 8, and an outlet port 28 is provided at the lower portion. A valve chamber 30 is formed inside the first body 6 and the second body 8. The inlet port 26 and the outlet port 28 are in communication with each other via the valve chamber 30.

[0016] An actuating rod 32 extending from the rotor 60 of the motor unit 3 is inserted into the inside of the body 5. The actuating rod 32 passes through the valve chamber 30. The actuating rod 32 is obtained by cutting a bar made of a non-magnetic metal, and a needle-shaped valve element 34 is provided integrally at its lower part. The valve element 34 is attached to and detached from the valve seat 24 from the valve chamber 30 side to open and close the valve portion.

[0017] A guide member 36 is erected at the center of the upper part of the first body 6. The guide member 36 is obtained by cutting a tube material made of a non-magnetic metal into a stepped cylindrical shape, and a male thread 38 is formed on the outer circumferential surface of the axial center part. The lower end part of the guide member 36 has a large diameter, and the large diameter part 40 is press-fitted into the upper center of the first body 6 and fixed coaxially. The guide member 36 supports the operating rod 32 axially slidably with its inner circumferential surface, and supports the rotating shaft 62 of the rotor 60 rotatably and slidably with its outer circumferential surface. The rotating shaft 62 is made of a non-magnetic metal.

[0018] A spring receiver 42 is provided on the operating rod 32 slightly above the valve body 34, and a spring receiver 44 is also provided on the bottom of the guide member 36. A spring 46 (functioning as a "biasing member") is interposed between the spring receivers 42, 44 to bias the valve body 34 in the valve closing direction.

[0019] On the other hand, the motor unit 3 is configured as a three-phase stepping motor including a rotor 60 and a stator 64. The motor unit 3 has a cylindrical can 66 with a bottom, with the rotor 60 disposed inside the can 66 and the stator 64 disposed outside the can 66. The can 66 is a cylindrical member with a bottom that covers the space in which the valve body 34 and its drive mechanism are disposed and contains the rotor 60, and defines an inner pressure space (internal space) where the pressure of the refrigerant acts and an outer non-pressurized space (external space) where the pressure of the refrigerant does not act.

[0020] The can 66 is made of a non-magnetic metal (SUS in this embodiment), and is assembled coaxially with its lower portion being fitted onto the upper end of the first body 6. The amount of insertion of the can 66 is regulated by engaging the lower end with the engaging portion 52. The body 5 and the can 66 are fixed and sealed by applying a full circumference weld (not shown) along the boundary between the lower end of the can 66 and the first body 6. The space surrounded by the body 5 and the can 66 forms the above-mentioned pressure space.

[0021] The stator 64 is configured by arranging a plurality of salient poles at equal intervals on the inner periphery of the laminated core 70. The laminated core 70 is configured by laminating annular cores in the axial direction. A bobbin 74 with a coil 73 (electromagnetic coil) attached thereto is attached to each salient pole. The coil 73 and the bobbin 74 form a "coil unit 75." In this embodiment, three coil units 75 for supplying three-phase current are provided at intervals of 120 degrees with respect to the central axis of the laminated core 70 (described in detail later).

[0022] The stator 64 is provided integrally with a case 76 of the motor unit 3. That is, the case 76 is obtained by injection molding (also called "insert molding" or "mold molding") of a corrosion-resistant resin material. The stator 64 is covered with the molded resin obtained by the injection molding. The case 76 is made of the molded resin. Hereinafter, the molded product of the stator 64 and the case 76 is also called a "stator unit 78."

[0023] The stator unit 78 has a hollow structure, and is assembled to the body 5 while the can 66 is coaxially inserted therethrough. A seal receiving portion 80 consisting of an annular groove is formed on the outer peripheral surface of the first body 6 slightly below the locking portion 52, and a seal ring 82 (O-ring) is fitted into the seal receiving portion 80. The seal ring 82 is interposed between the upper outer peripheral surface of the first body 6 and the lower inner peripheral surface of the case 76, thereby preventing the outside atmosphere (water, etc.) from entering the gap between the can 66 and the stator 64.

[0024] The rotor 60 includes a cylindrical rotor core 102 attached to the rotating shaft 62, a rotor magnet 104 provided on the outer peripheral surface of the rotor core 102, and a sensor magnet 106 provided on the upper end surface of the rotor core 102. The rotor core 102 is attached to the rotating shaft 62. The sensor magnet 106 is attached coaxially to the upper end of the rotor core 102 so as to be fitted onto the upper end of the rotor core 102. The rotor magnet 104 is magnetized (magnetized) with multiple poles in its circumferential direction. The sensor magnet 106 is also magnetized (magnetized) with multiple poles.

[0025] The rotating shaft 62 is a cylindrical shaft with a bottom, and is fitted onto the guide member 36 with its open end facing downward. A female thread 108 is formed on the inner peripheral surface of the lower part of the rotating shaft 62, and meshes with the male thread 38 of the guide member 36. A screw feed mechanism 109 formed by these threads converts the rotational motion of the rotor 60 into axial motion of the operating rod 32. This causes the valve element 34 to move (rise and fall) in the axial direction, that is, in the opening and closing direction of the valve portion.

[0026] The upper part of the actuation rod 32 is reduced in diameter, and the reduced diameter part 110 penetrates the bottom part 112 of the rotary shaft 62. An annular stopper 114 is fixed to the tip part of the reduced diameter part 110. Meanwhile, a spring 116 that urges the actuation rod 32 downward (i.e., in the valve closing direction) is interposed between the base end of the reduced diameter part 110 and the bottom part 112. With this configuration, when the valve is opened, the actuation rod 32 is displaced integrally with the rotor 60 in such a manner that the stopper 114 is engaged with the bottom part 112. Meanwhile, when the valve is closed, the spring 116 is compressed by the reaction force that the valve body 34 receives from the valve seat 24. The elastic reaction force of the spring 116 at this time can press the valve body 34 against the valve seat 24, improving the seating performance (valve closing performance) of the valve body 34.

[0027] The motor unit 3 has a circuit board 118 on the outside of the can 66. The circuit board 118 is fixed inside the case 76. In this embodiment, various circuits functioning as a control unit and a communication unit are mounted on the lower surface of the circuit board 118. Specifically, a drive circuit for driving the motor, a control circuit (microcomputer) for outputting a control signal 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), etc. are mounted. The upper end of the case 76 is closed by a lid 77. The circuit board 118 is disposed in the space below the lid 77 of the case 76.

[0028] A magnetic sensor 119 is provided on the surface of the circuit board 118 facing the sensor magnet 106. The magnetic sensor 119 faces the sensor magnet 106 in the axial direction via the bottom end wall of the can 66. The magnetic flux generated by the sensor magnet 106 changes as the rotor 60 rotates. The magnetic sensor 119 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 valve body 34 and therefore the valve opening degree based on the amount of displacement of the rotor 60.

[0029] A pair of terminals 117 connected to the coil 73 extend from each bobbin 74 and are connected to a circuit board 118. A power supply terminal, a ground terminal, and a communication terminal (collectively referred to as "connection terminals 81") extend from the circuit board 118 and are each drawn out to the outside through a side wall of the case 76. A connector portion 79 is integrally provided on the side of the case 76, and the connection terminals 81 are arranged inside the connector portion 79.

[0030] Fig. 2 is a diagram showing the configuration of the stator 64 and its surroundings. (A) corresponds to the cross section seen from the arrow AA in Fig. 1, and is a cross section of the stator unit 78. (B) shows only the stator 64 (before resin molding). For reference, the can 66 and the rotor 60 are shown in Fig. 2(A) (see the two-dot chain line).

[0031] Since the motor unit 3 is a three-phase motor, as shown in FIG. 2A, coil units 75 are provided at equal intervals around the axis L of the rotor 60. As also shown in FIG. 2B, slots 120a to 120c (collectively referred to as "slots 120" when no particular distinction is made) are provided at intervals of 120 degrees around the axis L on the inner periphery of the laminated core 70. In each slot 120, salient poles 122a to 122c (collectively referred to as "salient poles 122") protruding radially inward from the center are formed, and a U-phase coil 73a, a V-phase coil 73b, and a W-phase coil 73c (collectively referred to as "coils 73") are respectively assembled therein. Slits 124 having a U-shaped cross section are also formed between adjacent slots 120 to optimize the magnetic path.

[0032] The rotor magnet 104 faces the salient poles 122a to 122c via the can 66. In this embodiment, the rotor magnet 104 is magnetized with 10 poles as shown in Fig. 2(A). The number of poles can be set appropriately.

[0033] Next, the configuration of the magnets in the rotor 60 will be described in detail. 3 is a diagram showing the configuration of the rotor 60. (A) is a perspective view, (B) is a front view, (C) is a plan view, and (D) is a cross-sectional view taken along the line BB in (C). In the diagram, "N" indicates the north pole and "S" indicates the south pole. For ease of explanation, the rotating shaft 62 is omitted from Figs. 3(A) to (C).

[0034] The rotor 60 has a rotor magnet 104 along the outer circumferential surface of the rotor core 102, and a sensor magnet 106 is disposed at the axial end of the rotor core 102 (Figs. 3(A) and (D)). The rotor magnet 104 is cylindrical, and its outer circumferential surface is magnetized with 10 poles (Figs. 3(B) and (C)). On the other hand, the sensor magnet 106 is annular, and is magnetized with four poles on both sides in two upper and lower layers (double-sided magnetization with two poles on one side). That is, the sensor magnet 106 is magnetized so that its upper layer 106a and lower layer 106b each have two poles, and the polarity of the magnetic poles is reversed on both the upper and lower surfaces. This configuration strengthens the magnetic flux.

[0035] The rotor core 102 is made of a cylindrical magnetic metal (magnetic body). An annular groove 140 is formed along the outer circumferential surface of the rotor core 102 at the axial center (FIG. 3(D)). The inner circumferential surface of the rotor magnet 104 fits into the annular groove 140. That is, the annular groove 140 functions as a fall-out prevention structure that prevents the rotor magnet 104 from falling off the rotor core 102.

[0036] The rotating shaft 62 has a reduced diameter portion 63 at its upper portion, the outer diameter of which is slightly reduced. The shaft end portion 142 (upper end opening) of the rotor core 102 has an inner diameter that is slightly reduced so as to have a complementary shape to the reduced diameter portion 63, and serves as an axial stopper when the rotor core 102 is assembled to the rotating shaft 62.

[0037] The sensor magnet 106 is fitted onto the upper surface of the rotor core 102 while being extrapolated onto the reduced diameter portion 63 of the rotating shaft 62. By disposing the sensor magnet 106 on a magnetic body (the rotor core 102 in this embodiment) in this manner, the magnetic force of the sensor magnet 106 can be increased. The washer 65 is inserted coaxially onto the upper end of the rotating shaft 62 and the upper end is swaged, whereby the sensor magnet 106 is held between the shaft end 142 of the rotor core 102 and the washer 65.

[0038] Returning to FIG. 1, the motor-operated valve 1 configured as above functions as an electric expansion valve whose valve opening can be adjusted by controlling the drive of the motor unit 3. That is, based on a command from an external device (not shown), the control unit sets a control amount (the number of drive steps of the motor) for realizing a target opening, and outputs a drive signal for realizing this to the drive circuit. The drive circuit supplies a three-phase drive current (drive pulse) to each coil 73 at a set timing. This causes the rotor 60 to rotate with high resolution. At this time, if the valve body 34 is in an open state separated from the valve seat 24, the stopper 114 abuts against the rotating shaft 62 due to the biasing force of the spring 116, and the operating rod 32 and therefore the valve body 34 move integrally with the rotor 60.

[0039] The rotor 60 moves in the vertical direction by a screw feed mechanism 109 between it and the guide member 36. In other words, the valve element 34 translates in the opening and closing direction of the valve section, and the opening of the valve section is adjusted to a set opening. This screw feed mechanism 109 converts the rotational motion of the rotor 60 about the axis into axial motion (linear motion) of the operating rod 32, and drives the valve element 34 in the opening and closing direction of the valve section. When the motor-operated valve 1 is attached to a piping body and functions as an expansion valve, the valve section is controlled to a small opening.

[0040] The control unit detects the rotation angle of the sensor magnet 106 (the rotation angle of the rotor 60) based on the detection signal of the magnetic sensor 119, and can calculate the valve opening degree.

[0041] Next, the effects of this embodiment will be described. 4 is a diagram showing the operation of the sensor magnet 106 having two layers, upper and lower, and four poles on both sides. (A) shows the operation of the embodiment, and (B) shows the operation of a comparative example. The comparative example shows a case where the sensor magnet 126 has a two-pole structure with one layer, upper and lower. The dashed double-dashed arrows in the figure show the direction of magnetic flux in the sensor magnet.

[0042] In this embodiment, the sensor magnet 106 is magnetized on both sides (the magnetic poles are two layers, one above and one below), and the polarity of the magnetic poles is reversed on both sides, so that the magnetic flux coming out from one side is basically drawn into the other side. In contrast, in the comparative example, the magnetic poles are one layer, so that a part of the magnetic flux coming out from the magnetic poles of the sensor magnet 126 is drawn into the magnetic poles of the rotor magnet 104. That is, the magnetic field of the sensor magnet 126 interferes with the magnetic field of the rotor magnet 104, and there is a possibility that the balance of the magnetic flux between the rotor 60 and the stator 64 is lost. In other words, according to this embodiment, the balance of the magnetic flux between the rotor 60 and the stator 64 can be maintained better than in the comparative example, and the rotation of the rotor 60 can be maintained more stably.

[0043] 5 is a diagram showing the results of an analysis verifying the effect that the size of the inner diameter of sensor magnet 106 has on the magnetic flux density sensed by magnetic sensor 119. The horizontal axis of the figure indicates the distance between magnetic sensor 119 and sensor magnet 106, and the vertical axis indicates the magnitude of the magnetic flux density. This analysis shows the results when the inner diameter of sensor magnet 106 is changed from d1 to d5 (d1>d2>d3>d4>d5).

[0044] In this embodiment, as shown in Fig. 1, the sensor magnet 106 has a hole 107, inside which the upper end of the rotating shaft 62, the stopper 114, and the upper end of the actuation rod 32 are located. The rotating shaft 62 and the actuation rod 32 are provided coaxially, and the upper end of the rotating shaft 62 and the stopper 114 do not abut in the radial direction. In other words, a radial gap exists between the sensor magnet 106 and the actuation rod 32. In this analysis, in such a configuration, the effect of providing the hole 107 in the sensor magnet 106, more specifically, the size of the inner diameter of the hole 107, on the detection of magnetic flux by the magnetic sensor 119 was verified.

[0045] As shown in Fig. 5, it can be seen that, as a general trend, the greater the distance between the sensor magnet 106 and the magnetic sensor 119, i.e., the more the valve body 34 is displaced in the valve closing direction, the smaller the magnetic flux density detected by the magnetic sensor 119 becomes. In other words, the closer the sensor magnet 106 is to the magnetic sensor 119, the greater the magnetic flux, and the farther away the magnetic flux is, the smaller the magnetic flux. This in itself can be said to be a natural result. On the other hand, the larger the inner diameter of the sensor magnet 106 is, the smaller the change in magnetic flux density becomes, which is a new finding.

[0046] In this embodiment, the inner diameter of the sensor magnet 106 is set in the range of d1 to d3, thereby minimizing the change in magnetic flux density due to the stroke of the operating rod 32, i.e., the valve body 34. That is, a magnetic sensor generally has a recommended range of magnetic flux density to sense, and it is difficult to sense when the magnetic flux density is too large as well as when it is too small. In this regard, according to this embodiment, the inner diameter of the sensor magnet 106 is appropriately set, thereby making it possible to maintain good sensor sensitivity.

[0047] This analysis has revealed that, when the size of the hole 107 provided in the sensor magnet 106 is changed, the difference in magnetic flux density detected when the sensor magnet 106 and the magnetic sensor 119 are close to each other increases, but the difference in magnetic flux density detected when the two are separated can be kept small. This means that by ensuring a sufficient size of the hole 107, the magnetic flux density is prevented from becoming excessive when the two are close to each other, and a necessary and sufficient magnetic flux density can be ensured when the two are separated. In other words, the results of this analysis have confirmed the effectiveness of providing the hole 107 in the sensor magnet 106 in this embodiment and of making the size of the hole 107 larger to a certain extent.

[0048] As described above, according to this embodiment, the sensor magnet 106 is magnetized with four poles on both sides (two poles on each side), and the magnetic flux can be strengthened by reversing the polarity of the magnetic poles on both sides. Therefore, even if the rotor 60 is displaced in the valve closing direction and the distance between the sensor magnet 106 and the magnetic sensor 119 increases, the sensitivity of the magnetic sensor 119 can be maintained at a good level.

[0049] On the other hand, by providing a hole 107 in the center of the sensor magnet 106 and ensuring a sufficient inner diameter, the magnetic flux density acting on the magnetic sensor 119 is prevented from becoming excessive even if the rotor 60 is displaced in the valve opening direction and the sensor magnet 106 approaches the magnetic sensor 119. In other words, as described in relation to Fig. 5, the magnetic flux density acting on the magnetic sensor 119 can be kept within the recommended range regardless of the stroke of the valve disc 34, and the sensitivity of the magnetic sensor 119 can be maintained at a good level.

[0050] Furthermore, by magnetizing the sensor magnet 106 with four poles on both sides (two poles on each side) and reversing the polarity of the magnetic poles on both sides, as described in relation to Fig. 4, it is possible to prevent or suppress the magnetic field of the sensor magnet 126 from interfering with the magnetic field of the rotor magnet 104. As a result, it is possible to maintain the rotation of the rotor 60 more stably.

[0051] Furthermore, by providing the sensor magnet 106 at the axial end of the rotor core 102 and providing the hole 107 in the sensor magnet 106, a configuration is realized in which the sensor magnet 106 rotates coupled with the rotor core 102 instead of the actuation rod. This makes it possible to adjust the diameter of the hole 107 regardless of the diameter of the actuation rod 32. In other words, according to this embodiment, the degree of freedom in designing the sensor magnet 106 can be increased.

[0052] Although a preferred embodiment of the present invention has been described above, it goes without saying that the present invention is not limited to that specific embodiment, and various modifications are possible within the scope of the technical concept of the present invention.

[0053] 6 is a diagram showing the configuration of a rotor according to a modified example, in which (A) is a perspective view of a sensor magnet alone, (B) is a perspective view of the rotor, (C) is a plan view, and (D) is a front view. In this modification, the sensor magnet 206 is magnetized with eight poles on both sides (four poles on each side). That is, the sensor magnet 206 is magnetized so that its upper layer 206a and lower layer 206b each have four poles, and the polarity of the magnetic poles is reversed on both the upper and lower sides.

[0054] Even when such a configuration is adopted, since the sensor magnet 206 is magnetized on both sides and each side has multiple magnetic poles, it is possible to suppress the magnetic field of the sensor magnet 206 from affecting the rotor magnet 104. As a result, similar to the above embodiment, it is possible to improve the stability of the rotor 260.

[0055] In the above embodiment, an example has been shown in which the rotor core 102 and the rotating shaft 62 in the rotor 60 are configured as separate members. In a modified example, the rotor core and the rotating shaft may be integrally molded, and a threaded portion (female thread 108) may be provided on the inner peripheral surface. In this case, the rotor core also functions as a screw feed mechanism.

[0056] Although not mentioned in the above embodiment, the rotor magnet 104 may be obtained by magnetizing a magnet portion integrally molded with the rotor core 102 in a later process. Also, in the above embodiment, the rotor core 102 and the sensor magnet 106 are configured as separate members and are assembled together. In a modified example, the sensor magnet 106 may also be obtained by magnetizing a magnet portion integrally molded with the rotor core 102 in a later process. Both the rotor magnet portion and the sensor magnet portion may be integrally molded using the rotor core 102 as a base material and magnetized in a later process. The magnet portion may be molded by injection molding a magnetic material. Alternatively, the magnet portion may be molded by forging, extrusion molding, or other die molding.

[0057] In the above embodiment, a configuration has been exemplified in which one double-sided magnetized sensor magnet 106 is provided. In a modified example, a plurality of double-sided magnetized sensor magnets may be disposed in series in the axial direction of the rotating shaft.

[0058] In the above embodiment, the sensor magnet 106 is provided at the axial end of the rotor core 102. In a modified example, the sensor magnet may be provided at the axial end of the actuation rod. Alternatively, the sensor magnet may be separated from the rotor core and fixed to the rotating shaft of the rotor.

[0059] In the above embodiment, a configuration in which the actuating rod 32 rotates coaxially with the rotor 60 has been exemplified. In a modified example, a configuration in which the actuating rod does not rotate may be adopted. For example, in the configuration shown in FIG. 1, a slide bearing may be provided between the stopper 114 and the rotor 60 to prevent the actuating rod 32 from rotating. In addition, the rotational motion of the rotor may be transmitted to the actuating rod by a gear so that the axis of the actuating rod does not coincide with the axis of the rotor.

[0060] In the above embodiment, a configuration has been exemplified in which the upper ends of the rotating shaft 62 and the actuating rod 32 are inserted into the hole 107 of the sensor magnet 106. In a modified example, a configuration may be adopted in which either or both of the rotating shaft and the actuating rod of the rotor are not inserted into the hole 107 of the sensor magnet. In that case, the sensor magnet and the rotor core may be fixed by fitting, press-fitting, or other means.

[0061] In the above embodiment, the rotor 60 and the actuation rod 32 are displaced together in the axial direction in the open state. That is, the rotor 60 supports the actuation rod 32 coaxially, and the rotor 60 itself is displaced in the axial direction. In a modified example, as described in Patent Document 1, the rotor may be fixed in position in the axial direction. That is, the actuation rod may be configured by connecting a shaft that rotates together with the rotor and a driver having an integral valve body in the axial direction. The driver rotates together with the shaft, but is relatively displaceable in the axial direction. The rotational motion of the rotor is converted into the axial motion of the driver by a screw feed mechanism.

[0062] In the above embodiment, an example has been shown in which the magnetic sensor detects the amount of rotation (rotation angle) of the rotor, and the control unit calculates the axial displacement of the actuating rod (stroke of the valve body, i.e., the opening of the valve section) based on the amount of rotation. In a modified example, the magnetic sensor may directly detect the axial displacement of the rotor (i.e., the axial displacement of the actuating rod), and the control unit may calculate the stroke of the valve body (i.e., the opening of the valve section) based on that displacement. In other words, the magnetic sensor may be one that detects the amount of displacement of the rotor (i.e., the amount of displacement of the sensor magnet).

[0063] In the above embodiment, the rotor magnet 104 and the sensor magnet 106 are axially separated from each other. In a modified example, the rotor magnet and the sensor magnet may be integrally formed. The rotor magnet portion and the sensor magnet portion may be integrally molded. In that case, the area (outer diameter) of the sensor magnet may be increased so that the magnetic sensor can reliably detect the magnetic flux.

[0064] Although not mentioned in the above embodiment, the valve body and the piping body may be collectively referred to as the "body of the motor-operated valve."

[0065] In each embodiment, a laminated core (laminated magnetic core) is exemplified as the core of the stator. In a modified example, a dust core or other core may be adopted. A dust core is also called a "powder core" and is obtained by powdering a soft magnetic material, coating the powder with a non-conductive resin or the like, kneading the powder with a resin binder, and compression molding and heating it.

[0066] In each embodiment, a configuration in which the drive circuit, control circuit, communication circuit, and power supply circuit are mounted on the underside of the circuit board has been illustrated, but the circuits to be mounted can be changed as appropriate. For example, the drive circuit and power supply circuit may be mounted, while the control circuit may be installed outside the motor-operated valve. In addition, each circuit may be mounted on the upper surface of the circuit board.

[0067] In each embodiment, a PM type stepping motor is used as the motor unit, but a hybrid type stepping motor may also be used. In the above embodiments, the motor unit is a three-phase motor, but it may be another type of motor such as a two-phase, four-phase, or five-phase motor. The number of electromagnetic coils in the stator is not limited to three or six, and may be set appropriately according to the number of phases of the motor.

[0068] The motor-operated valve of each embodiment is preferably applied to a refrigeration cycle that uses a refrigerant such as an alternative fluorocarbon (HFC-134a) as a refrigerant, but can also be applied to a refrigeration cycle that uses a refrigerant with a high operating pressure such as carbon dioxide. In that case, an external heat exchanger such as a gas cooler is disposed in the refrigeration cycle instead of a condenser.

[0069] In each embodiment, the motor-operated valve is configured as an expansion valve, but it may be configured as an opening / closing valve or a flow control valve that does not have an expansion function.

[0070] In each embodiment, the motor-operated valve is applied to the refrigeration cycle of an automotive air conditioner, but the motor-operated valve can be applied to any air conditioner equipped with an electric expansion valve, not limited to vehicles. Also, the motor-operated valve can be configured to control the flow of a fluid other than a refrigerant.

[0071] In the above embodiment, the sensor magnet 106 is magnetized on both the top and bottom surfaces, and the polarity of the magnetic poles is reversed at corresponding positions on both surfaces. That is, in the sensor magnet 106, the boundary lines of the magnetic poles coincide on the top and bottom surfaces. In a modified example, a sensor magnet in which the magnetic poles on both the top and bottom surfaces are not reversed at some positions may be used. That is, the boundary lines of the magnetic poles may not completely coincide on the top and bottom surfaces, but may be slightly shifted. In that case, the top and bottom surfaces will have the same polarity at some positions, so the effect may be inferior to that of the above embodiment, but it may be possible to obtain an effect that does not cause any problems in practical use.

[0072] The present invention is not limited to the above-mentioned embodiment and modified examples, and the components can be modified without departing from the gist of the present invention. Various inventions can be formed by appropriately combining multiple components disclosed in the above-mentioned embodiment and modified examples. In addition, some components can be deleted from all the components shown in the above-mentioned embodiment and modified examples. [Explanation of symbols]

[0073] 1 motor-operated valve, 2 valve body, 3 motor unit, 5 body, 22 valve hole, 24 valve seat, 26 inlet port, 28 outlet port, 30 valve chamber, 32 operating rod, 34 valve body, 36 guide member, 38 male screw, 46 spring, 60 rotor, 62 rotating shaft, 63 reduced diameter portion, 64 stator, 65 washer, 66 can, 70 laminated core, 73 coil, 76 case, 78 stator unit, 102 rotor core, 104 rotor magnet, 106 sensor magnet, 106a upper layer, 106b lower layer, 107 hole portion, 108 female screw, 109 screw feed mechanism, 114 stopper, 116 spring, 118 circuit board, 119 magnetic sensor, 126 sensor magnet, 142 shaft end, 206 Sensor magnet, 206a upper layer, 206b lower layer.

Claims

1. an actuation rod that supports the valve body in the axial direction; a rotor for actuating the actuation rod; a rotor magnet having a plurality of magnetic poles provided along an outer circumferential surface of the rotor; a screw feed mechanism for converting the rotational motion of the rotor into the axial motion of the actuation rod; a sensor magnet provided coaxially with the rotor and rotatable integrally with the rotor; a magnetic sensor that faces the sensor magnet in the axial direction and detects the amount of displacement of the rotor by detecting a magnetic flux of the sensor magnet; Equipped with The sensor magnet is magnetized such that the polarities are inverse on both sides in the axial direction, and each side has a plurality of magnetic poles in the rotational direction. The rotor has a rotor core made of a magnetic material, The rotor magnet is provided on an outer peripheral surface of the rotor core, the sensor magnet is configured as a separate member from the rotor core and is attached to a shaft end of the rotor core; a magnetic portion of the rotor core between the rotor magnet and the sensor magnet, the magnetic portion being not magnetized.

2. a can that is a cylindrical member that contains the rotor and that defines an internal space in which a fluid pressure acts and an external space in which the fluid pressure does not act; The magnetic sensor is disposed in the external space, 2. The motor-operated valve according to claim 1, wherein the sensor magnet and the magnetic sensor face each other across an end wall of the can.

3. The screw feed mechanism displaces the rotor together with the actuation rod in the axial direction, 3. The motor-operated valve according to claim 1, wherein the sensor magnet moves toward or away from the magnetic sensor by operation of the screw feed mechanism.

4. 4. The motor-operated valve according to claim 1, wherein the sensor magnet is provided with a hole along an axis thereof.

5. 5. The motor-operated valve according to claim 1, wherein the sensor magnet has four or more magnetic poles on each surface.

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