Motor-operated valve

Abstract

An electric valve 11 comprising: a main valve body 12 having a valve chamber 13 that communicates with an inflow passage 15 for introducing a refrigerant and an outflow passage 16 for discharging the refrigerant; a valve body 17 that changes the flow rate of the refrigerant by advancing and retreating with respect to a valve seat 14 formed in the valve chamber between a closed state in which the valve body is seated on the valve seat and an open state in which the valve body is apart from the valve seat; and an electric motor 45 that drives the valve body. The electric motor has: a stator 46 including a coil 49 that is supplied with a current to generate a magnetic force; and a magnet rotor 36 that is disposed on the inner side of the stator and rotates by receiving the magnetic force generated by the coil. The electric valve further comprises a magnetic sensor 62 that detects the magnetic force of the magnet rotor. In the electric valve, a magnetic shield member (made from, for example, a soft magnetic material) 61 is provided so as to be interposed between the magnetic sensor and the coil.

Description

[Technical field]

[0001] The present invention relates to an electrically operated valve, and more particularly to an electrically operated valve equipped with a magnetic sensor that detects the rotation of a magnet rotor. [Background technology]

[0002] 2. Description of the Related Art Motor-operated valves, which use an electric motor such as a stepping motor to control the valve opening, have conventionally been used in refrigeration cycle devices equipped with refrigerant circuits, such as air conditioners and refrigeration / freezing devices.

[0003] Furthermore, some such motor-operated valves are equipped with a magnetic sensor that detects the rotation angle and direction of the magnet rotor (hereinafter sometimes simply referred to as the "rotor"), enabling accurate detection of the valve opening and more precise control (see, for example, Patent Document 1 below). [Prior art documents] [Patent documents]

[0004] Patent Document 1: JP 2021-110409 A Summary of the Invention

[0005] From the standpoint of detection accuracy, it is preferable to dispose the magnetic sensor that detects the magnetism of the magnet rotor as close as possible to the rotor.

[0006] However, when a coil placed close to the rotor is excited by energizing it, the magnetic force generated in the coil may saturate from the stator and leak to the surroundings, depending on the stator material, the number of coil turns, the value of the current supplied, etc., resulting in an increase in the magnetic flux density around the coil. For this reason, if a magnetic sensor is placed close to the coil, the magnetic sensor may be affected by the leakage magnetic flux from the coil, which may result in erroneous detection.

[0007] On the other hand, the invention described in Patent Document 1 is provided with a magnetic transmission member that transmits the magnetism of the rotor, making it possible to detect the magnetism of the rotor using a magnetic sensor housed in a case located away from the rotor (and therefore away from the coil).

[0008] However, the invention described in the document requires the provision of two separate magnetic transmission members, and each magnetic transmission member passes directly above the coil and extends to a position close to the rotor, making it impossible to eliminate the possibility of being affected by leakage magnetic flux from the coil via the magnetic transmission members.

[0009] Furthermore, no mention has been made of this issue, namely the possibility that leakage magnetic flux from a coil in a motor-operated valve may affect a magnetic sensor, in any of the prior art, including in Patent Document 1.

[0010] Therefore, an object of the present invention is to newly present and solve the problem, and to prevent the magnetic sensor from being affected by leakage magnetic flux from a coil, resulting in erroneous detection.

[0011] In order to solve the above problems and achieve the object, the electric valve of the present invention comprises a valve body having a valve chamber communicating with an inlet passage for introducing a refrigerant and an outlet passage for discharging the refrigerant, a valve disc that changes the flow rate of refrigerant by moving toward and away from a valve seat formed in the valve chamber between a closed valve state in which it is seated on the valve seat and an open valve state in which it is spaced from the valve seat, and an electric motor that drives the valve disc, the electric motor having a stator including a coil that generates magnetic force when supplied with electric current, and a magnet rotor that is disposed inside the stator and rotates in response to the magnetic force generated by the coil, the electric valve further comprising a magnetic sensor that detects the magnetic force of the magnet rotor, and a magnetic shield member that is interposed between the magnetic sensor and the coil.

[0012] In the motor-operated valve of the present invention, a magnetic shield member is provided between the magnetic sensor and the coil, which can prevent or suppress leakage magnetic flux from the coil from reaching the magnetic sensor, thereby preventing erroneous detection by the magnetic sensor.

[0013] Although the type of material constituting the magnetic shield member is not particularly limited as long as it has a magnetic shielding effect, it is preferable to form the magnetic shield member from a member made of a magnetic material, in particular, a soft magnetic material with high magnetic permeability, in order to collect leakage magnetic flux in the coil (pass through the magnetic shield member) and prevent the leakage magnetic flux from reaching the magnetic sensor.

[0014] In addition, in the above-mentioned electric valve, the magnet rotor is arranged to penetrate the stator and has a protrusion protruding from at least one of the axial end faces of the stator, and the magnetic sensor is arranged at a certain distance from one end face of the stator and facing the protrusion in the radial direction of the magnet rotor.

[0015] In this embodiment, the magnetism of the rotor is detected by a magnetic sensor arranged to face the protruding part of the rotor, but because a magnetic shield member is provided between the coil and the magnetic sensor based on the present invention, even if the protruding part is shortened (if the protruding part is shortened, the magnetic sensor arranged to face that part will be closer to the coil), the magnetic sensor is less susceptible to the influence of the coil. Therefore, by shortening the rotor (reducing the height), it is possible to reduce the manufacturing cost of the motor-operated valve (rotor) and also to reduce the size (height) of the motor-operated valve.

[0016] In the above-described aspect, when the stator has a ring-shaped planar shape with a central hole through which the magnet rotor passes, and the one end face of the stator is the upper end face, the magnetic shield member may be a flat plate member having a ring-shaped planar shape that covers the upper end face.

[0017] According to such an embodiment in which the upper end surface of the stator is covered with a magnetic shielding member, leakage magnetic flux from the coil can be blocked more reliably, and the magnetic sensor can be protected from leakage magnetic flux. Note that the above-mentioned "ring-shaped planar shape" does not necessarily mean that the outer shape (outer periphery) and the shape of the center hole are circular, but is a concept that includes shapes in which either or both of the outer shape and the center hole are circular, as well as shapes such as ovals and polygons.

[0018] In the above-mentioned aspect, it is preferable to fix the magnetic shield member by a resin molded part that covers the coil, in order to minimize the number of steps and parts required in manufacturing the motor-operated valve and reduce manufacturing costs.

[0019] More specifically, if a magnetic shielding member is provided as a subassembly, a process for producing the subassembly and a process for assembling it to the motor-operated valve are required in addition to the coil molding process, increasing the number of steps during manufacturing. Also, if the magnetic shielding member is attached to the stator by a fixing method such as welding or fastening (screw fastening) or a fixing bracket, a new work process such as welding is required, and a mechanism for positioning the magnetic shielding member during the work is also required.

[0020] In contrast, according to the above-mentioned embodiment in which the magnetic shielding member is fixed by the resin molded part that covers the coil, the magnetic shielding member is insert-molded together with the coil as an insert part, so that assembly is possible by simply adding the magnetic shielding member when molding the resin layer that covers the coil, and the magnetic shielding member can be incorporated into the motor-operated valve without increasing the number of steps. Also, with this fixing structure, there is no need to add any parts to fix the magnetic shielding member, so the number of additional parts can be kept to a minimum (only the magnetic shielding member).

[0021] Furthermore, during the coil molding process, a core pin (cylindrical jig) may be inserted into the center hole of the coil (stator) to place the coil in the mold. If the diameter of the center hole of the ring-shaped magnetic shielding member is set to be the same (or approximately the same) as the diameter of the center hole of the stator, the magnetic shielding member can be positioned simply by inserting it into the core pin together with the coil, eliminating the need for a positioning mechanism for incorporating the magnetic shielding member.

[0022] Furthermore, according to the above-described embodiment in which the magnetic shield member is fixed by a flowable molding resin during molding, even if it becomes necessary to change the shape of the magnetic shield member (for example, to change the outer diameter, thickness, etc.), the resin flows and solidifies to match the changed shape, making it possible to incorporate the magnetic shield member with the changed shape without changing the process or fixing structure.

[0023] Note that the above-mentioned "covering the coil" in relation to the resin molded part does not only mean covering the outside (the outer peripheral surface, top surface, bottom surface, etc.), but also includes the concept of covering the inside (the inner peripheral surface, etc.) For example, in an embodiment described later, after an inner molding process is performed in which the inside of the coil (windings, etc.) is covered with resin, an outer molding process is performed in which the outside of the coil is covered, and in the outer molding process, the magnetic shielding member is fixed (by the mold cover formed in the outer molding process), but as described with reference to Figures 8 and 9, it is also possible to fix the magnetic shielding member by the resin molded part formed in the inner molding process.

[0024] According to the motor-operated valve of the present invention, it is possible to prevent the magnetic sensor from being affected by leakage magnetic flux from the coil, which would otherwise cause erroneous detection.

[0025] Other objects, features and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments of the present invention, taken in conjunction with the accompanying drawings. In the drawings, the same reference numerals indicate the same or corresponding parts. [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is a vertical sectional view showing a motor-operated valve according to a first embodiment of the present invention in a closed state. [Diagram 2] FIG. 2 is a vertical sectional view showing the motor-operated valve according to the first embodiment in an open state. [Diagram 3] FIG. 3 is a partially cutaway perspective view showing the main parts (the relationship between the magnetic sensor, the magnet rotor, the coil, and the magnetic shield member) of the motor-operated valve according to the first embodiment. [Figure 4] FIG. 4 is a plan view showing the main parts (the relationship between the magnetic sensor, the magnet rotor, the coil, and the magnetic shield member) of the motor-operated valve according to the first embodiment. [Diagram 5] FIG. 5 is a side view showing the main parts (the relationship between the magnetic sensor, the magnet rotor, the coil, and the magnetic shield member) of the motor-operated valve according to the first embodiment. [Figure 6] FIG. 6 is a cross-sectional view showing a manufacturing process of the motor-operated valve according to the first embodiment (a coil outer molding process / a process of fixing the magnetic shield member by insert molding when molding the mold cover). [Figure 7] FIG. 7 is a perspective view that typically illustrates an outer molding process of the coil (a process of fixing a magnetic shield member by insert molding). [Figure 8] FIG. 8 is a cross-sectional view showing a method for fixing the magnetic shield member in the coil inner molding process. [Figure 9] FIG. 9 is a perspective view that illustrates a coil to which a magnetic shield member is fixed in an inner molding process. [Figure 10] FIG. 10 is a diagram showing magnetic flux of a coil when the motor-operated valve of the first embodiment is not provided with a magnetic shield member. [Figure 11] FIG. 11 is a diagram showing magnetic flux of a coil in the motor-operated valve (provided with a magnetic shield member) according to the first embodiment. [Figure 12] FIG. 12 is a side view showing another example of the arrangement of the magnetic shield member of the motor-operated valve according to the first embodiment. [Figure 13]FIG. 13 is a plan view showing another example of the magnetic shield member of the motor-operated valve according to the first embodiment. [Figure 14] FIG. 14 is a plan view showing still another example of the magnetic shield member of the motor-operated valve according to the first embodiment. [Figure 15] FIG. 15 is a vertical sectional view showing a configuration example for obtaining the same effect as the motor-operated valve according to the first embodiment, which is provided with a magnetic shield member. [Figure 16] FIG. 16 is a vertical sectional view showing a motor-operated valve according to the second embodiment of the present invention in a closed state. [Figure 17] FIG. 17 is a vertical sectional view showing the motor-operated valve according to the second embodiment in an open state. BEST MODE FOR CARRYING OUT THEINVENTION

[0027] [First embodiment] As shown in Figs. 1 to 5, a motor-operated valve 11 according to a first embodiment of the present invention is an motor-operated valve suitable for use in adjusting the flow rate of a refrigerant in a refrigeration cycle device such as an air conditioner, and comprises a valve body 12 having a valve chamber 13 therein, an inflow passage 15 for introducing a refrigerant into the valve chamber 13, and an outflow passage 16 for discharging the refrigerant from the valve chamber 13, a valve seat 14 formed at the opening of the inflow passage 15 to the valve chamber 13, and a valve seat 14 that moves forward and backward (up and down) relative to the valve seat 14 between a closed state in which the valve seat 14 abuts against the valve seat 14 (see Fig. 1) and an open state in which the valve seat 14 is spaced apart from the valve seat 14 (see Fig. 2). the valve body 17 which changes the amount of refrigerant passing through (flow rate), an electric motor 45 which drives the valve body 17, a reduction mechanism (paradox planetary gear reduction mechanism) 43 which reduces the speed of the rotation of the electric motor 45, a transmission mechanism (screw feed mechanism) 28 which converts the reduced rotational motion into linear motion and transmits it to the valve body 17, a connecting member 19 which connects the electric motor 45 to the valve body 12, a can (sealed container) 33 which covers an upper opening 12a of the valve body 12 which communicates with the valve chamber 13 and which forms a sealed space together with the connecting member 19, a magnetic sensor 62 which detects the rotation of the electric motor 45, and a connector 53 which provides electrical connection to the outside.

[0028] In each drawing, mutually orthogonal two-dimensional or three-dimensional coordinates representing the front-rear, left-right, and up-down directions are appropriately shown, and the following description will be based on these directions.

[0029] The electric motor 45 is a stepping motor equipped with a stator 46 arranged outside the can 33 and a magnet rotor 36 arranged rotatably inside the can 33. The magnet rotor 36 protrudes upward from the upper surface of the stator 46, and a magnetic sensor 62 is arranged on the upper surface of the stator 46 so as to face the protruding part of the rotor 36 across the side wall of the can 33. This is to ensure that the magnetic sensor 62 can reliably detect the rotation of the rotor 36. The magnetic sensor 62 is made up of a Hall IC including a Hall element and an amplifier, and outputs a signal corresponding to the direction and magnitude of the magnetic flux (magnetic flux density) passing through the magnetic sensing surface.

[0030] Furthermore, the motor-operated valve 11 of this embodiment is provided with a magnetic shield member 61 on the upper surface of the stator 46 so as to be interposed between the magnetic sensor 62 and the stator 46. This magnetic shield member 61 is a plate-like member having a ring-shaped planar shape (in this embodiment, the planar shapes of the outer periphery and the center hole are both perfect circles) so as to cover the upper surface of the ring-shaped stator 46. The magnetic shield member is formed of a high magnetic permeability material, which in this embodiment is permalloy (an iron-nickel soft magnetic material), so as to be able to collect (collect and pass through) leakage magnetic flux from the coil 49 in the stator 46.

[0031] The number of magnetic sensors 62 is not limited to one, and it is possible to provide a plurality of magnetic sensors 62 in order to detect, for example, the rotation direction of the rotor 36. In such an embodiment, a magnetic shield member 61 may be provided so as to be interposed between the plurality of magnetic sensors 62 and the stator 46.

[0032] The connecting member 19 is a cylindrical member having a large diameter hole 19a and a small diameter hole 19b which are through holes communicating with each other. The large diameter hole 19a passes through the upper center of the connecting member 19 and has a large diameter so that a bearing member 27 described later can be inserted from above. The small diameter hole 19b passes through the lower center of the connecting member 19 and has a small diameter. A bottomless, lidded cylindrical can 33 (with an open bottom and a closed top) is joined to the outer circumferential surface of the upper end of the connecting member 19 via a ring-shaped base plate 29.

[0033] The stator 46 disposed outside the can 33 includes a yoke (stator yoke) 47, a bobbin 48, a coil 49, and a resin molded cover 51. The rotor 36 disposed inside the can 33 is configured by integrally connecting a cylindrical rotor member 36a made of a magnetic material (permanent magnet) and a sun gear member 37 made of a resin material. The rotor 36 has a plurality of N poles and a plurality of S poles arranged alternately in the circumferential direction on its outer circumferential surface, the N poles and the S poles extending in the direction of the rotation axis of the rotor 36 (which coincides with the central axis A of the motor-operated valve 11) (see FIG. 4).

[0034] A shaft 34 is inserted into the center of the sun gear member 37 , and the upper part of the shaft 34 is supported by a support member 35 arranged on the inside of the top of the can 33 .

[0035] The sun gear 37a of the sun gear member 37 meshes with a plurality of planetary gears 38 rotatably supported on a shaft 39 provided on a carrier 41 placed on the bottom surface of the output gear 42. The upper part of the planetary gear 38 meshes with an annular ring gear (internal tooth fixed gear) 44 attached to the upper part of the cylindrical member 32 fixed to the upper part of the connecting member 19, and the lower part of the planetary gear 38 meshes with an internal tooth gear 40 of the annular output gear 42. The number of teeth of the ring gear 44 and the number of teeth of the internal tooth gear 40 of the output gear 42 are slightly different, so that the rotation speed of the sun gear 37a is reduced at a large reduction ratio and transmitted to the output gear 42. These gear mechanisms (sun gear 37a, planetary gear 38, ring gear 44 and output gear 42) constitute a speed reduction mechanism (paradise planetary gear speed reduction mechanism) 43 that reduces the rotation speed of the stepping motor 45 described above.

[0036] A cylindrical bearing member 27 is inserted into the large diameter hole 19a at the top of the connecting member 19 and fixed by crimping. The output gear 42 is in slidable contact with the upper surface of the bearing member 27. The upper part of a stepped cylindrical output shaft 31 is press-fitted into the center of the bottom of the output gear 42, and the lower part of the output shaft 31 is rotatably inserted into a fitting hole 27a formed in the center of the upper surface of the bearing member 27. The lower end of a shaft 34 is rotatably fitted into the upper part of the output shaft 31.

[0037] A female thread portion 27b is formed at the lower center portion of the bearing member 27, and this female thread portion 27b is screwed into a male thread portion 26b formed on the outer peripheral surface of the screw drive member 26. The bearing member 27 (female thread portion 27b) and the screw drive member 26 (male thread portion 26b) constitute the above-mentioned screw feed mechanism 28, i.e., a transmission mechanism that converts the rotational motion supplied from the stepping motor 45 via the reduction mechanism 43 into linear motion in the vertical direction and transmits it to the valve body 17.

[0038] Here, the output gear 42 rotates at a fixed position in the vertical direction without moving up and down, and a flat screwdriver-shaped plate-like portion 26a provided at the upper end of the screw drive member 26 is inserted into a slit-shaped fitting groove 31a provided at the lower end of the output shaft 31 connected to the output gear 42 to transmit the rotational motion of the output gear 42 to the screw drive member 26. Although the output gear 42 does not move up and down when the output gear 42 (rotor 36) rotates due to the plate-like portion 26a provided on the screw drive member 26 sliding up and down within the fitting groove 31a of the output shaft 31, the screw drive member 26 moves linearly up and down by the screw feed mechanism 28.

[0039] The linear motion of the screw drive member 26 is transmitted to the valve body 17 via a ball joint 23 consisting of a ball 24 and a ball seat 25, and the upper spring receiving member 22. The valve body 17 is composed of a valve body main body 17a that moves toward and away from the valve seat 14, and a stepped cylindrical valve body support part 17b that rises upward from the center of the upper surface of the valve body main body part 17a, and the upper spring receiving member 22 and the valve body 17 (valve body support part 17b) are connected by inserting the upper end part of the valve body support part 17b into a fitting hole (lower surface fitting hole) 22b formed in the center of the lower surface of the upper spring receiving member 22. A fitting hole (upper surface fitting hole) 22a is also provided in the center of the upper surface of the upper spring receiving member 22, and a ball seat 25 is fitted into this upper surface fitting hole 22a. Furthermore, the upper spring receiving member 22 is inserted into the small diameter hole 19b of the connecting member 19 so as to be movable up and down.

[0040] In addition, a lower spring receiving member 18 and a connecting member 19 are screwed into the upper opening 12a of the valve body 12 in this order to fix the valve body 12 to close the upper opening 12a of the valve chamber. A stepped through hole is formed in the center of the lower spring receiving member 18 fixed to the upper part of the valve chamber 13, through which the valve body support part 17b passes so as to be vertically slidable and in which a compression coil spring 21 is installed. The compression coil spring 21 is provided between the step at the top of the through hole and the upper spring receiving member 22. The compression coil spring 21 biases the valve body 17 upward (in the valve opening direction), and by applying the biasing force of the coil spring 21 to the valve body 17 in addition to the driving force of the electric motor 45 during the valve opening operation, the valve opening operation can be performed more reliably.

[0041] The can 33 and the stator 46 are covered by a molded cover 51 made of synthetic resin. A box-shaped case 52 for accommodating a printed circuit board (hereinafter, simply referred to as a "board") 55 is formed integrally with the molded cover 51 on the side (front) of the molded cover 51, and a connector 53 having an external connection terminal 54 inside is formed integrally with the case 52 and the molded cover 51 on the upper surface of the case 52. A board 55 is accommodated inside the case 52, and the coil 49 and the magnetic sensor 62 are electrically connected to the external connection terminal 54 via the board 55. Power can be supplied from an external power source (not shown) to the coil 49, and a signal output from the magnetic sensor 62 can be output to the outside through the external connection terminal 54. The board 55 may be equipped with a motor drive circuit including a pulse generator for supplying a drive current to the coil 49, as well as a calculation device for calculating the rotation angle of the rotor 36 and the opening degree of the valve based on the output signal from the magnetic sensor 62.

[0042] The magnetic shield member 61 is fixed by being integrated with the molded cover 51 (wrapped in the molded cover 51) as an insert part when the molded cover 51 is molded (outer mold).

[0043] Specifically, to form the molded cover 51 as shown in Fig. 6 and Fig. 7, the inner-molded coil 49 (wounds and the like covered by resin molding) is placed in a mold. The mold has an upper mold 81, a lower mold 82, and a core pin (cylindrical jig) 83, and a space (resin flow space) 84 is formed between the inner surface of the mold and the coil 49, where the resin flows to form the molded cover 51. When placing the coil 49 in the mold, the coil 49 is placed so that the core pin 83 is inserted into the center hole, and the magnetic shield member 61 is placed on the top surface of the coil 49 so that the core pin 83 is inserted into the center hole as well. The portion where the core pin 83 is placed becomes the space for inserting the can 33 in a later manufacturing process.

[0044] Then, by filling the resin flow space 84 with resin and allowing it to harden, the magnetic shield member 61 can be integrated with the molded cover 51 and fixed so as to be embedded in the molded cover 51 .

[0045] Thus, according to this embodiment, the magnetic shield member 61 can be incorporated by simply arranging the magnetic shield member 61 together with the coil 49 in the mold when molding the mold cover 51, and no separate process (just for fixing) for fixing the magnetic seal member 61 or any member for fixing is required. In addition, the magnetic shield member 61 is a ring-shaped member into which the core pin 83 can be inserted, and is positioned by the core pin 83 together with the coil 49, so no positioning means is required. Furthermore, since it is ring-shaped, it can be incorporated by a simple operation of simply inserting the core pin 83 without worrying about the position (particularly the circumferential position) at which the magnetic sensor 62 is placed when placing the magnetic shield member 61 in the mold. In addition, since it is fixed by being wrapped in a molding resin having fluidity, it can be incorporated without any problem even if the shape (for example, thickness, outer diameter, etc.) of the magnetic shield member 61 is changed.

[0046] Also, it is possible to fix the magnetic shield member 61 during the inner molding process, rather than during the outer molding process as described above.

[0047] Specifically, prior to the outer molding, inner molding is performed to cover the windings of coil 49 with resin. In the inner molding process, coil 49 (unmolded coil) is placed in a metal mold for inner molding that includes upper die 91, lower die 92, and core pin 93 as shown in Fig. 8, and magnetic shield member 61 is placed together with coil 49 with core pin 93 passing through the center hole. Then, resin is filled into resin flow space 94 in the metal mold and allowed to solidify, whereby magnetic shield member 61 can be fixed by inner mold resin 95 as shown in Fig. 9.

[0048] The operation of the motor-operated valve 11 according to this embodiment will be described as follows.

[0049] When a current is supplied to the stator 46 (coil 49) so that the rotor 36 rotates in one direction from the closed valve state shown in Fig. 1, the rotation of the rotor 36 is converted into linear motion by the screw feed mechanism 28, and the screw drive member 26 is pulled upward. As a result, the upper spring receiving member 22, which is pressed against the lower surface of the screw drive member 26 via the ball joint 23 by the urging force of the compression coil spring 21, and the valve body 17 (valve body support part 17b) connected to the upper spring receiving member 22 are pulled upward, and the valve body 17 (valve body main body part 17a) is separated from the valve seat 14, and the refrigerant that has flowed in from the inflow path 15 passes through the valve chamber 13 and flows out from the outflow path 16 (see Fig. 2). The amount of refrigerant passing through in this open valve state (refrigerant flow rate) can be adjusted by the amount of rotation of the rotor 36.

[0050] On the other hand, when a current is supplied to the stator 46 (coil 49) so that the rotor 36 rotates in the opposite direction from the open valve state, the rotation of the rotor 36 is converted into linear motion by the screw feed mechanism 28, and the screw drive member 26 moves downward. With this downward movement, the ball joint 23, the upper spring receiving member 22, and the valve body 17 move downward, and when the valve body 17 (valve body main body portion 17a) abuts against the valve seat 14, the flow path between the inflow path 15 and the outflow path 16 is blocked, and the valve is closed (see FIG. 1).

[0051] The advantages and modifications of this embodiment (which also applies to the second embodiment described later) are as follows.

[0052] In a conventional structure not provided with a magnetic shield member as shown in Fig. 10, when magnetic flux leakage occurs from the coil 49, the leaked magnetic flux M is likely to reach the magnetic sensor 62 disposed on the upper surface of the coil 49. In contrast, in the motor-operated valve 11 of this embodiment as shown in Fig. 11, a magnetic shield member 61 is provided between the magnetic sensor 62 and the coil 49, so that the leakage magnetic flux M passes through the magnetic shield member 61 and is less likely to reach the magnetic sensor 62. Therefore, it is possible to prevent the magnetic sensor 62 from erroneously detecting the leakage magnetic flux M.

[0053] Furthermore, in the electric valve 11 of this embodiment, the entire upper surface of the stator 46 as viewed from the magnetic sensor 62 is covered by the magnetic shielding member 61, so that leakage magnetic flux from the coil 49 can be blocked more reliably, and the magnetic sensor 62 can be protected more reliably from leakage magnetic flux.

[0054] Furthermore, by providing the magnetic shielding member 61, the magnetic sensor 62 can be positioned closer to the stator 46 without being affected by the leakage magnetic flux of the coil 49, so that the magnet rotor 36 can be made shorter (the vertical dimension can be reduced), which has the advantage of reducing the manufacturing cost of the electric valve 11 and making the electric valve 11 thinner (reducing its size in the vertical direction).

[0055] The magnetic shield member 61 does not necessarily have to be fixed to the upper surface of the stator 46, and may be disposed away from the upper surface of the stator 46 as shown in FIG.

[0056] Furthermore, the magnetic shield member 61 may have a sectorial planar shape as shown in FIG. 13, a rectangular planar shape as shown in FIG. 14, or another shape.

[0057] Furthermore, the object of the present invention can also be achieved by increasing the thickness t of the top plate portion 46a (stator yoke or stator cover made of a magnetic material) of the stator 46, which is interposed between the magnetic sensor 62 and the coil 49, as shown in FIG. 15, without providing the magnetic shield member 61, or with the magnetic shield member 61 (in combination with the magnetic shield member 61).

[0058] Second Embodiment A motor-operated valve according to a second embodiment of the present invention will be described with reference to FIGS.

[0059] 16 and 17, the motor-operated valve 71 of this embodiment adjusts the flow rate of the refrigerant by moving the valve element 17 up and down using the motor (stepping motor) 45, similar to the motor-operated valve 11 of the first embodiment, and is provided with a magnetic sensor 62 on the upper surface of the coil 49 for detecting a change in magnetic flux caused by the rotation of the magnet rotor 36 included in the motor 45. However, unlike the motor-operated valve 11 of the first embodiment, the valve is opened and closed by the valve shaft 72 having the valve element 17 at its lower end and the magnet rotor 36 moving up and down together. Hereinafter, the same components as those of the motor-operated valve 11 of the first embodiment are denoted by the same reference numerals, and duplicated explanations will be omitted, and the differences will be mainly described.

[0060] 16 and 17, the motor-operated valve 71 according to this embodiment includes a rod-shaped valve shaft 72 that extends vertically from the inside of the magnet rotor 36 to the valve chamber 13 along the central axis A of the motor-operated valve 71. The valve shaft 72 has a cylindrical body 72a and an upper small-diameter portion 72b with a small outer diameter that is formed coaxially at the upper end of the body 72a and continues from the body 72a, and the valve element 17 is integrally provided at the lower end of the valve shaft 72. In this embodiment, the magnet rotor 36 is provided inside the can 33 so as to be rotatable and slidable in the vertical direction.

[0061] A valve stem holder 73 is provided inside the magnet rotor 36. The valve stem holder 73 has a cylindrical shape with its upper end closed, and a support ring 75 is fixed to the upper end of the valve stem holder 73 by crimping. The rotor 36 and the valve stem holder 73 are joined together via the support ring 75. A female thread portion 73a is formed on the inner circumferential surface of the valve stem holder 73.

[0062] The upper small diameter portion 72b of the valve stem 72 passes through the valve stem holder 73, and a push nut 76 is attached to the upper end of the upper small diameter portion 72b to prevent it from coming off. The valve stem 72 is urged downward by a compression coil spring 77 provided between the valve stem holder 73 and a step between the body portion 72a and the upper small diameter portion 72b of the valve stem 72. Therefore, the push nut 76 and the compression coil spring 77 restrict the valve stem 72 from moving up and down relative to the valve stem holder 73, and the valve stem 72 moves up and down together with the valve stem holder 73.

[0063] The connecting member 19 installed on the upper surface of the valve body 12 has a large diameter hole 19a and a small diameter hole 19b as in the first embodiment, but in this embodiment, a guide bush 78 is inserted into the large diameter hole 19a instead of a bearing member. The guide bush 78 has a large diameter cylindrical portion 78a with a large outer diameter and a small diameter cylindrical portion 78b with a small outer diameter formed coaxially at the upper end of the large diameter cylindrical portion 78a and continuing from the large diameter cylindrical portion 78a. A male thread portion 78c that screws into the female thread portion 73a of the valve stem holder 73 is formed on the outer circumferential surface of the small diameter cylindrical portion 78b. The guide bush 78 is connected to the connecting member 19 by press-fitting the large diameter cylindrical portion 78a into the inside of the connecting member 19. The body portion 72a of the valve stem 72 passes through the small diameter hole 19b of the connecting member 19.

[0064] Furthermore, the stem holder 73 is provided with an upper stopper body 74, while the large diameter cylindrical portion 78a of the guide bush 78 is provided with a lower stopper body 79. These stopper bodies 74, 79 determine the lower limit position of the stem holder 73. When the stem holder 73 rotates and descends to reach the lower limit position, the upper stopper body 74 comes into contact with the lower stopper body 79, thereby restricting further rotation of the stem holder 73.

[0065] The operation of the motor-operated valve 71 according to this embodiment will be described as follows.

[0066] When a current is supplied to the stator 46 (coil 49) so that the rotor 36 rotates in one direction from the closed valve state shown in Fig. 16, the stem holder 73 connected to the rotor 36 rotates together with the rotor 36. The inner peripheral surface of the stem holder 73 is formed with a female thread 73a that screws with a male thread 78c formed on the outer peripheral surface of the small diameter cylindrical portion 78b of the guide bush 78, and the interaction between the male thread 78c and the female thread 73a converts the rotation of the rotor 36 (stem holder 73) into a vertical linear motion, so that the stem holder 73 moves upward, and the rotor 36 connected to the stem holder 73 and the stem 72, whose relative movement with the stem holder 36 is restricted, also move upward together with the stem holder 73. As the valve shaft 72 moves upward, the valve element 17 provided at the lower end of the valve shaft 72 moves away from the valve seat 14, and the refrigerant that has flowed in from the inlet passage 15 passes through the valve chamber 13 and flows out from the outlet passage 16 (see FIG. 17). The amount of refrigerant passing through (refrigerant flow rate) can be adjusted by the amount of rotation of the rotor 36.

[0067] On the other hand, when a current is supplied to the stator 46 (coil 49) so that the rotor 36 rotates in the opposite direction from the open state, the rotation of the rotor 36 (valve stem holder 73) is converted into vertical linear motion due to the interaction between the female thread portion 73a and the male thread portion 78c, and the valve stem holder 73 moves downward together with the rotor 36 and the valve stem 72. This causes the valve element 17 to descend toward the valve seat 14, and when the valve element 17 abuts against the valve seat 14, the flow path between the inflow path 15 and the outflow path 16 is blocked, resulting in a closed valve state (see FIG. 16).

[0068] In the motor-operated valve 71 of this embodiment, the rotor 36 moves in the axial direction in accordance with the opening and closing operation of the valve as described above, but in any state from the fully closed state where the valve is completely closed (see FIG. 16) to the fully open state where the valve is fully open (see FIG. 17), the upper end of the rotor 36 protrudes upward (in the axial direction) from the upper surface of the stator 46, and the protruding portion of the rotor 36 and the magnetic sensor 62 face each other in the radial direction. This is to ensure that the magnetic force of the rotor 36 is detected by the magnetic sensor 62. The motor-operated valve 71 of this embodiment also has a magnetic shield member 61 similar to that of the first embodiment, and can obtain the same effects.

[0069] Although the embodiments of the present invention have been described above, the present invention is not limited to these, and it will be apparent to those skilled in the art that various modifications can be made within the scope of the claims.

[0070] For example, the transmission mechanism for transmitting the driving force from the electric motor 45 to the valve body 17 is not limited to the above-described embodiments, and may have various structures different from those of the above-described embodiments. In the above-described embodiments, the case 52 for accommodating the substrate 55 is provided on the side surface of the stator 46. However, the case 52 may be provided on the upper surface of the stator 46, for example, and the substrate 55 may be disposed on the upper surface of the stator 46. [Explanation of symbols]

[0071] A Center axis M magnetic flux 11,71 Motor-operated valve 12 Valve body 12a Top opening 13 Valve chamber 14 Valve seat 15 Inflow channel 16 Outflow channel 17 Valve body 17a Valve body 17b Valve body support part 18 Lower spring support member 19 Connecting members 19a Large diameter hole 19b Small diameter hole 21 Compression coil spring 22 Upper spring support member 22a Top fitting hole 22b Bottom fitting hole 23 Ball joint 24 Ball 25 Ball seat 26 Screw drive member 26a Plate-shaped part 26b Male thread 27 Bearing materials 27a Insertion hole 27b Female thread 28 Screw feed mechanism 29 Base Plate 31 Output shaft 31a Fitting groove 32 Cylindrical member 33 Can 34 Shaft 35 Support member 36 Magnet rotor 36a Rotor member 37 Sun gear parts 37a Sun Gear 38 Planetary Gear 39 Shaft 40 Internal gear 41 Career 42 Output gear 43 Reduction mechanism (paradoxical planetary gear reduction mechanism) 44 Ring gear (internal tooth fixed gear) 45 Stepping motor (electric motor) 46 Stator 46a Stator top plate 47 York 48 Bobbin 49 Coil 51 Molded cover 52 cases 53 Connector 54 External connection terminal 55 Substrate 61 Magnetic shielding materials 62 Magnetic Sensor 72 Valve stem 72a Torso 72b Upper small diameter section 73 Valve stem holder 73a Female thread 74 Upper stopper body 75 Support Ring 76 Push Nut 77 Compression coil spring 78 Guide bush 78a Large diameter cylindrical section 78b Small diameter cylindrical section 78c Male thread 79 Lower stopper body 81,91 Upper mold 82,92 Lower mold 83,93 Core pin 84,94 Resin flow space 95 Inner mold resin

Claims

1. a valve body having a valve chamber communicating with an inlet passage for introducing a refrigerant and an outlet passage for discharging the refrigerant; a valve element that moves toward and away from a valve seat between a valve closed state in which the valve element is seated on a valve seat formed in the valve chamber and an open state in which the valve element is spaced from the valve seat to change a flow rate of the refrigerant; an electric motor for driving the valve body; Equipped with The electric motor is a stator including a coil that generates a magnetic force when supplied with a current; a magnet rotor that is disposed inside the stator and rotates by receiving the magnetic force generated by the coil; having The magnet rotor further includes a magnetic sensor for detecting the magnetic force of the magnet rotor. A motor-operated valve, a magnetic shield member disposed between the magnetic sensor and the coil; the magnet rotor is disposed so as to penetrate the stator and includes a protruding portion protruding from at least one of both end faces of the stator in the axial direction; the magnetic sensor is disposed at a certain distance from one end face of the stator and facing the protruding portion in a radial direction of the magnet rotor, the stator has a ring-like planar shape having a center hole through which the magnet rotor passes, When the one end surface of the stator is defined as an upper end surface, The magnetic shield member is a flat plate member having a ring-like planar shape that covers the upper end surface of the stator. A motor-operated valve.

2. a valve body having a valve chamber communicating with an inlet passage for introducing a refrigerant and an outlet passage for discharging the refrigerant; a valve element that moves toward and away from a valve seat between a valve closed state in which the valve element is seated on a valve seat formed in the valve chamber and an open state in which the valve element is spaced from the valve seat to change a flow rate of the refrigerant; an electric motor for driving the valve body; Equipped with The electric motor is a stator including a coil that generates a magnetic force when supplied with a current; a magnet rotor that is disposed inside the stator and rotates by receiving the magnetic force generated by the coil; having The magnet rotor further includes a magnetic sensor for detecting the magnetic force of the magnet rotor. A motor-operated valve, a magnetic shield member disposed between the magnetic sensor and the coil; The stator includes: The magnet rotor has a ring-like planar shape having a central hole through which the magnet rotor passes, It has coils arranged in two layers, one above the other, The magnet rotor is connected at its upper portion to the valve body side, When one end surface of the stator is the upper end surface, The magnetic shield member is a flat plate member having a ring-like planar shape that covers the upper end surface of the stator. A motor-operated valve.

3. The magnetic shield member is made of a soft magnetic material. The motor-operated valve according to claim 1 or 2.

4. The stator is covered by a mold cover, The magnetic shield member is fixed between the upper surface of the inner molded coil and a mold cover formed in an outer mold. The motor-operated valve according to claim 1 or 2.

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