Electric valve

Abstract

An electric valve 11 includes: a valve body 12 having a valve chamber 13; a first flow passage 14 communicating with the valve chamber; a second flow passage 15 communicating with the valve chamber; an orifice 16 provided between the first flow passage and the second flow passage; a valve body 18 for changing the opening of the orifice by moving forward / backward relative to the orifice; a rotor 24 constituting an electric motor 51 for driving the valve body; a gear device 22 for decelerating rotation of the rotor; an output shaft 36 for outputting rotation decelerated by the gear device; a transmission mechanism 43 for converting rotation of the output shaft into linear motion for transmission to the valve body; a cylindrical gear case 23 storing the gear device; and a guide part 37 rotatably supporting the output shaft. The output shaft, the guide part, and the gear device are supported by the gear case.

Description

Motor-operated valve

[0001] The present invention relates to an electric valve, and more particularly to the structure of a gear portion that reduces the rotation speed of an electric motor.

[0002] Electric valves that use an electric motor such as a stepping motor to control the valve opening have traditionally been used in refrigeration cycle devices that have refrigerant circuits, such as air conditioners, refrigerators, and freezers.One such electric valve is a gear-type electric valve that has a gear device that slows down the rotation of the electric motor.

[0003] Such an electric valve comprises an electric motor that drives the valve element, a gear device that reduces the rotation of the electric motor, an output shaft that outputs the rotation reduced by the gear device, and a transmission mechanism that converts the rotation of the output shaft into linear motion and transmits it to the valve element, and controls the flow rate of the fluid by moving the valve element back and forth relative to an orifice formed in the flow path.

[0004] Furthermore, the following Patent Document 1 discloses an invention relating to such a gear-type motor-operated valve.

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2009-228889

[0006] Although the invention described in Patent Document 1 improves the assembly of the motor-operated valve and enables rotational testing and evaluation, thereby increasing the reliability of the motor-operated valve, there is still room for further improvement in these respects.

[0007] Specifically, in the invention described in Patent Document 1, a gear assembly (gear module) in which the gears that make up the gear device are unitized is prepared in advance, and this is then assembled into the electric valve, thereby improving assembly during manufacturing.

[0008] However, this gear assembly does not incorporate all of the gears that make up the gear device, and an additional gear (sun gear) must be incorporated during manufacturing.

[0009] Furthermore, in terms of improving reliability, the electric valve described in Patent Document 1 does not have all the gears of the gear device as described above, and although it has an output shaft that outputs rotation reduced by the gear device, this output shaft is not supported by a guide portion. Therefore, in the gear assembly state, it is not possible to perform tests such as checking the operation of the gear device as a whole or measuring and confirming the reduction ratio.

[0010] Therefore, an object of the present invention is to further improve the assembly ease of a gear-type electric valve and to enable testing of the gear device as a whole, thereby further increasing the reliability of the electric valve.

[0011] In order to solve the above problems and achieve the object, the motor-operated valve of the present invention comprises a valve body having a valve chamber therein, a first flow path communicating with the valve chamber, a second flow path communicating with the valve chamber, an orifice formed between the first flow path and the second flow path, a valve element that moves toward and away from the orifice to change the opening of the orifice, a rotor that constitutes an electric motor that drives the valve element, a gear device that reduces the rotation of the rotor, an output shaft that outputs the rotation reduced by the gear device, a transmission mechanism that converts the rotation of the output shaft into linear motion and transmits it to the valve element, a cylindrical gear case that houses the gear device, and a guide part that rotatably supports the output shaft, and the output shaft, the guide part, and the gear device are supported by the gear case.

[0012] In conventional gear-type motor-operated valves, including the motor-operated valve disclosed in the aforementioned Patent Document 1, the gear assembly includes an output shaft that outputs rotation reduced by a gear device, but a guide portion supporting the output shaft is provided on the transmission mechanism. Specifically, the transmission mechanism includes a feed screw (screw mechanism) that includes a male-threaded member (screw shaft; referred to herein as a "screw drive member") connected to the output shaft so as to be axially movable, and a bearing (referred to herein as a "bearing member") having a female-threaded portion that threadably engages with the male-threaded member. The output shaft is supported by being rotatably fitted over the bearing. For this reason, in conventional motor-operated valves, it is not possible to perform inspections such as checking the operation or measuring the reduction ratio of the gear device alone (without combining it with the transmission mechanism; the same applies hereinafter).

[0013] In contrast, in the motor-operated valve of the present invention, the guide portion of the output shaft is not provided on a bearing as in the conventional case, but is supported on the gear case separately from the transmission mechanism (bearing). This makes it possible to perform various tests and inspections, such as operation tests, on the gear device alone, further improving the reliability of the motor-operated valve. In addition, by providing the gear device (all necessary gears) within the gear case, the motor-operated valve can be assembled more easily than in the conventional case.

[0014] Furthermore, in the past, bearings in transmission mechanisms were generally made of metal to ensure durability, and the guide portion of the output shaft integrated with the bearing was also forced to be made of metal. In contrast, according to the present invention, the guide portion of the output shaft is provided separately from the transmission mechanism (bearing member). Therefore, while the bearing member is made of metal to ensure durability, the guide portion can be formed from, for example, a slidable resin (a resin with high slidability), which also reduces the sliding resistance of the guide portion. Furthermore, the use of a slidable resin allows the support portion of the output shaft to have a greaseless structure. The guide portion can be provided inside the gear case, for example, by insert molding.

[0015] In a typical embodiment of the present invention, the gear device, gear case, output shaft, guide, and rotor are unitized as a gear device assembly. "Unitization" refers to the construction of a single, cohesive unit (assembly of parts) that is made up of multiple parts and can be incorporated into an electric valve. Furthermore, the gear device assembly may include a central shaft that rotatably supports the rotor and a support member that supports the central shaft within the can, as in the embodiment described below.

[0016] The gear device can be configured with a paradox planetary gear mechanism as in the embodiment described later. However, the gear device referred to in the present invention is not limited to a paradox planetary gear mechanism, and can also be configured with other planetary gear mechanisms or gear mechanisms other than planetary gear mechanisms.

[0017] In the motor-operated valve according to the present invention, it is preferable that one of the inner circumferential surface of the gear case and the outer circumferential surface of the guide portion is provided with an engagement recess, and the other of the inner circumferential surface of the gear case and the outer circumferential surface of the guide portion is provided with an engagement protrusion that fits into the engagement recess to prevent rotation of the guide portion. This is to prevent the guide portion from falling off the gear case and from rotating together with the output shaft. In other words, the engagement recess and the engagement protrusion work together to prevent the guide portion from moving (misaligning) in the axial direction of the gear case and from rotating.

[0018] The "engagement recess" is a portion recessed relative to (in other words, as seen from) the other side (the guide portion when provided on the gear case side, or the gear case when provided on the guide portion side). On the other hand, the "engagement protrusion" is a portion protruding relative to (in other words, as seen from) the other side (the guide portion when provided on the gear case side, or the gear case when provided on the guide portion side).

[0019] Furthermore, according to the present invention, a guide portion is provided separately from the transmission mechanism (bearing member), and therefore a space can be provided between the gear device (gear case and output shaft) and the transmission mechanism. Therefore, in a preferred embodiment of the motor-operated valve of the present invention, the space is utilized to provide a rotation detection means for detecting the rotation of the screw drive member.

[0020] Specifically, in the electric valve of this embodiment, the transmission mechanism includes a screw drive member that rotates in response to the rotation of the output shaft and is movable back and forth relative to the output shaft, and has a male threaded portion on its outer surface, and a bearing member that has a female threaded portion that screws into the male threaded portion of the screw drive member, and the electric valve further includes a drive permanent magnet that is housed in the lower part of the gear case and fixed to the screw drive member to rotate together with the screw drive member, a driven permanent magnet that is connected to the drive permanent magnet by a magnetic coupling and is arranged outside the outer peripheral surface of the lower part of the gear case so that rotational force is transmitted from the drive permanent magnet, and a magnetic sensor that detects the rotation of the driven permanent magnet.

[0021] The screw drive member constituting the transmission mechanism is connected to the output shaft so as to be slidable in the axial direction in order to function as a feed screw (the function of converting rotation received from the output shaft into linear motion). Therefore, a certain gap (a clearance to allow relative movement) is required between the output shaft and the screw drive member. Therefore, to detect the position (axial displacement) of the valve disc more accurately, it is preferable to detect the rotation of the screw drive member rather than the rotation of the rotor or output shaft. However, in conventional valve structures, as described above, the guide portion supporting the output shaft is provided on the transmission mechanism (bearing), making it difficult to detect the rotation of the screw drive member located inside the bearing due to space constraints. In contrast, according to the above-described aspect of the present invention, detecting the rotation of the screw drive member makes it possible to more accurately detect the displacement of the valve disc (valve opening).

[0022] According to the present invention, it is possible to further improve the ease of assembly and reliability of the gear type motor-operated valve.

[0023] Other objects, features, and advantages of the present invention will become apparent from the following description of the preferred embodiments of the present invention, which is given with reference to the accompanying drawings. It will be apparent to those skilled in the art that the present invention is not limited to the following embodiments, and that various modifications can be made within the scope of the claims. In addition, the same reference numerals in the various drawings indicate the same or equivalent parts.

[0024] FIG. 1 is a longitudinal sectional view showing a motor-operated valve (closed state) according to a first embodiment of the present invention. FIG. 2 is a longitudinal sectional view showing an enlarged gear device assembly of the motor-operated valve according to the first embodiment. FIG. 3 is a partial cross-sectional view of the lower part of the gear device assembly (a cross-section taken along arrows B-B in FIG. 2). FIG. 4 is a longitudinal sectional view showing a motor-operated valve (open state) according to the first embodiment. FIG. 5 is a longitudinal sectional view showing a motor-operated valve (closed state) according to a second embodiment of the present invention. FIG. 6 is an enlarged view of a rotation detection unit (portion C in FIG. 5) of the motor-operated valve according to the second embodiment. FIG. 7 is a plan view (view from above) showing the rotation detection unit (drive permanent magnet, driven permanent magnet, and magnetic sensor) of the motor-operated valve according to the second embodiment. FIG. 8 is a longitudinal sectional view showing a motor-operated valve (open state) according to the second embodiment.

[0025] [First embodiment] A motor-operated valve according to a first embodiment of the present invention will be described with reference to Figures 1 to 4. Note that in each figure, mutually orthogonal two-dimensional coordinate axes representing up, down, left, and right are appropriately displayed, and the following description will be based on these directions. However, the motor-operated valve of this invention and this embodiment (as well as the second embodiment described below) can be used in various orientations, and the directions are used for the convenience of explanation, and the configuration of each part of the present invention is not limited in any way by these directions.

[0026] As shown in FIGS. 1 to 4 , the motor-operated valve 11 according to this embodiment is an motor-operated valve suitable for use in adjusting the flow rate of a refrigerant in a refrigeration cycle device such as a heat pump type heating and cooling system, and includes a valve body 12 having an internal valve chamber 13 and an inlet passage (first passage) 14 for introducing a refrigerant into the valve chamber 13 and an outlet passage (second passage) 15 for discharging the refrigerant from the valve chamber 13; an orifice (valve port) 16 formed between the inlet passage 14 and the valve chamber 13 (the opening of the inlet passage 14 relative to the valve chamber 13); a valve element 18 that moves back and forth (up and down) relative to the orifice 16 to change the opening degree of the orifice 16; and a valve element 18 that is provided to close the upper surface of the valve chamber 13 and supports the valve element 18 so that it can slide up and down. The valve body 12 includes a support member 19, an electric motor 51 that drives the valve body 18, a gear device 22 that reduces the speed of the rotation generated by the electric motor 51, an output shaft 36 that outputs the rotation reduced by the gear device 22, an output shaft guide member (hereinafter simply referred to as the "guide member") 37 that supports the output shaft 36 so that it can rotate and slide, a transmission mechanism 43 that converts the rotation of the output shaft 37 into linear motion using a feed screw mechanism and transmits it to the valve body 18, a cylindrical gear case 23 that houses the gear device 22, a connecting member 40 that connects the electric motor 51 and the valve body 12, and a can (sealed container) 42 that has a cylindrical shape with no bottom and a lid (the bottom is open and the top is closed) and that, together with the connecting member 40, forms a sealed space on the upper surface of the valve body 12.

[0027] A valve seat 17 is formed at the valve chest side end of the orifice 16, against which a valve element 18 comes into contact and separates. The inflow passage 14 is provided with a mesh strainer 20 that allows the refrigerant to pass through but can capture foreign matter.

[0028] The electric motor 51 is a stepping motor that includes a stator 52 disposed outside the can 42 and a rotor (magnet rotor) 24 disposed rotatably inside the can 42 .

[0029] The stator 52 disposed outside the can 42 includes a yoke (stator yoke) 53, a coil 55 wound around a bobbin 54, and a resin molded cover 56. The rotor 24 disposed inside the can 42 is configured by integrally connecting a cylindrical rotor member 25 made of a magnetic material (permanent magnet) and a sun gear member 26 made of a resin material.

[0030] A central shaft 27 is inserted into the center of the sun gear member 26 , and the upper part of the central shaft 27 is supported by a support member 28 arranged inside the top of the can 42 .

[0031] The sun gear 29 of the sun gear member 26 meshes with a plurality of planet gears 33 rotatably supported on a shaft 32 provided on a carrier 31 mounted on the bottom surface of the output gear 30. The upper parts of the planet gears 33 mesh with an annular ring gear (internal fixed gear) 34 attached to the upper part of the gear case 23 fixed to the upper part of the connecting member 40, and the lower parts of the planet gears 33 mesh with an internal gear 35 of the annular output gear 30. The number of teeth of the ring gear 34 and the number of teeth of the internal gear 35 of the output gear 30 are slightly different, so that the rotation speed of the sun gear 29 is reduced at a large reduction ratio and transmitted to the output gear 30. Note that these gear mechanisms (sun gear 29, planet gears 33, ring gear 34, and output gear 30) form a paradox planetary gear reduction mechanism and constitute the gear device 22 that reduces the rotation of the electric motor 51 described above.

[0032] The upper part of a stepped cylindrical output shaft 36 is press-fitted into the center of the bottom of the output gear 30, connecting the output gear 30 and the output shaft 36.

[0033] Meanwhile, a guide member (referred to as a guide portion in the present invention) 37 that supports the output shaft 36 is provided at the inner bottom of the gear case 23. This guide member 37 has a through-hole 37a in the center, and the lower part of the output shaft 36 is slidably and rotatably held within this through-hole 37a. The output gear 30 is in slidable contact with the upper surface of the guide member 37. Note that, in order to reduce the sliding resistance of the output gear 30 and the output shaft 36, the guide member 37 is formed from a slidable resin (e.g., PTFE / Polytetrafluoroethylene). The lower end of the center shaft 27 is fitted into the upper part of the output shaft 36 so as not to impede the rotation of the output shaft 36.

[0034] Furthermore, to prevent the guide member 37 from falling off the gear case 23 and to prevent the guide member 37 from rotating in conjunction with the rotation of the output shaft 36, a fitting structure is formed between the gear case 23 and the guide member 37. Specifically, the fitting structure is formed by recessing the peripheral wall of the gear case 23 inward to form a convex portion (engagement convex portion) 38 on the gear case 23 that protrudes toward the center of the gear case 23, and by forming a concave portion (engagement concave portion) 39 on the outer peripheral surface of the guide member 37 into which the convex portion 38 fits (see FIGS. 2 and 3 ). In this embodiment, two fitting structures (pairs of convex portion 38 and concave portion 39) are provided, one pair on each side at diametrically opposed positions, but the number of fitting structures may be one, three or more.

[0035] The guide member 37 may also be fixed to the gear case 23 by insert molding. In insert molding, a resin material that will form the guide member 37 is introduced into a mold in which the metal gear case 23 is placed, and then molded. For this purpose, a convex portion may be formed on one of the gear case 23 and the guide member 37, and a concave portion may be formed on the other of the gear case 23 and the guide member 37. Alternatively, a concave portion or a through-hole may be provided in the gear case 23, and the guide member 37 may be insert molded therein. In this case, a part of the guide member 37 fits into the concave portion or the through-hole and is fixed.

[0036] Furthermore, when manufacturing the motor-operated valve 11 according to this embodiment (as well as the second embodiment described later), the gear device 22, gear case 23, output shaft 36, guide member 37, rotor 24, center shaft 27, and support member 28 are unitized as a gear device assembly 21. FIG. 2 shows an enlarged view of this unitized gear device assembly (also referred to as an "assembly" in the present application) 21. By fabricating such unitized assemblies 21, the productivity of the motor-operated valve 11 can be improved. For example, if multiple types of assemblies 21 with different gear ratios are prepared, selecting from these assemblies allows immediate response to specification changes corresponding to the load on the valve disc. Furthermore, the assembly 21 can be assembled into various types of valve bodies 12 having different thread pitches of the feed screw mechanism 43 (described later) and different valve orifice diameters.

[0037] Furthermore, since the assembly 21 includes all gears and also has a guide member 37 that supports the output shaft 36, it is possible to perform test inspections such as operation tests and performance inspections of the gear section that slows down the rotation of the electric motor 51, thereby further improving the reliability of the electric valve 11.

[0038] The connecting member 40, which connects the electric motor 51 and the valve body 12, is a cylindrical member having a large-diameter hole 40a and a small-diameter hole 40b that are through-holes that communicate with each other. The large-diameter hole 40a passes through the upper center of the connecting member 40 and has a large diameter so that a bearing member 44 (described later) can be inserted from above. The small-diameter hole 40b passes through the lower center of the connecting member 40 and has a small diameter. A can 42 is joined to the outer peripheral surface of the upper end of the connecting member 40 via a ring-shaped base plate 41.

[0039] A bearing member 44 is inserted and fixed into the large-diameter hole 40a at the top of the connecting member 40. The bearing member 44 is a cylindrical member having a central hole that passes through in the vertical direction, and a female thread (female thread portion) 44a is formed on the inner peripheral surface of the central hole. A screw drive member 45 is provided within the central hole of the bearing member 44. A male thread (male thread portion) 45a is formed on the outer peripheral surface of the screw drive member 45, which screws into the female thread portion 44a of the bearing member 44. The male thread portion 45a (screw drive member 45) and the female thread portion 44a (bearing member 44) constitute the aforementioned feed screw mechanism, i.e., the transmission mechanism 43 that converts the rotational motion supplied from the stepping motor 51 via the gear device 22 into linear motion in the vertical direction and transmits it to the valve disc 18.

[0040] Here, the output gear 30 rotates at a fixed position in the vertical direction without moving up and down, and a flat screwdriver-shaped plate-like portion 45b provided at the upper end of a screw drive member 45 is inserted into a slit-shaped fitting groove 36a provided at the lower end of an output shaft 36 connected to the output gear 30, thereby transmitting the rotational motion of the output gear 30 to the screw drive member 45. The plate-like portion 45b provided on the screw drive member 45 slides up and down within the fitting groove 36a of the output shaft 36, and as the output gear 30 (rotor 24) rotates, the screw drive member 45 moves linearly up and down by the transmission mechanism (feed screw mechanism) 43, even though the output gear 30 does not move up and down.

[0041] The linear motion of this screw drive member 45 is transmitted to the valve element 18 via a ball joint 46 consisting of a ball 47 and a ball seat 48, and a spring receiving member 49. The valve element 18 comprises a valve element main body 18a that moves toward and away from the valve seat 17, and a stepped, cylindrical valve stem 18b that rises upward from the center of the upper surface of the valve element main body 18a. The upper end of the valve stem 18b is fitted into a fitting hole (lower surface fitting hole) 49a formed in the center of the lower surface of the spring receiving member 49, connecting the spring receiving member 49 and the valve element 18 (valve stem 18b). A fitting hole (upper surface fitting hole) 49b is also formed in the center of the upper surface of the spring receiving member 49, and the ball seat 48 is fitted into this upper surface fitting hole 49b. Furthermore, the spring receiving member 49 is fitted into the small diameter hole 40b of the connecting member 40 so as to be movable up and down.

[0042] The valve disc support member 19 and the connecting member 40 are screwed into the top opening of the valve body 12 in that order to close the top opening at the top of the valve chamber. The valve disc support member 19, which is fixed to the top of the valve chamber 13, has a stepped through-hole in its center, through which the valve stem 18b passes so as to be able to slide up and down, and in which a compression coil spring 50 is installed. The compression coil spring 50 is provided between the stepped portion at the top of the through-hole and the spring receiver 49. The compression coil spring 50 constantly urges the valve disc 18 upward (in the valve-opening direction) via the spring receiver 49. As a result, even when the screw drive member 45 moves upward, the screw drive member 45 and the valve disc 18, which are in contact via the ball joint 46, do not separate, and the screw drive member 45 and the valve disc 18 are integrated in the vertical direction. Furthermore, when the valve is opened, the biasing force of the compression coil spring 50 is applied to the valve element 18 in addition to the driving force of the electric motor 51, so that the valve can be opened more reliably.

[0043] The screw drive member 45 on the drive unit side rotates and slides about the central axis A relative to the valve element 18 via the ball 47, and the rotation of the screw drive member 45 is not transmitted to the valve element 18. In this embodiment, the valve element 18, spring bearing member 49, ball joint 46 (ball 47 and ball seat 48), screw drive member 45, bearing member 44, output shaft 36, central shaft 27, guide member 37, orifice 16 (valve seat 17), valve element support member 19, connecting member 40, rotor 24, and other components are arranged coaxially, and the central axis A of these components coincides with the rotation axis (central axis) A of the rotor 24.

[0044] The operation of the motor-operated valve according to this embodiment will be described as follows.

[0045] When current is supplied to the stator 52 (coil 55) so that the rotor 24 rotates in one direction from the closed valve state shown in Figure 1, the rotation of the rotor 24 is converted into linear motion by the transmission mechanism 43, and the screw drive member 45 is pulled upward. Accordingly, the spring seat 49, which is pressed against the underside of the screw drive member 45 via the ball joint 46 by the biasing force of the compression coil spring 50, and the valve stem 18b, which is connected to the spring seat 49, are pulled upward, and the valve body 18a moves away from the valve seat 17, opening the orifice 16. Refrigerant flowing in from the inlet passage 14 passes through the valve chamber 13 and flows out of the outlet passage 15 (see arrow F in Figure 4). The amount of refrigerant passing through (flow rate) in this open valve state can be adjusted by the amount of rotation of the rotor 24.

[0046] On the other hand, when current is supplied to the stator 52 (coil 55) so that the rotor 24 rotates in the opposite direction from the open valve state, the rotation of the rotor 24 is converted into linear motion by the transmission mechanism 43, and the screw drive member 45 moves downward. As this downward movement occurs, the ball joint 46, spring bearing member 49, and valve body 18 move downward, and when the valve body main body 18a abuts against the valve seat 17, the orifice 16 is closed, blocking the flow path between the inlet channel 14 and the outlet channel 15, and the valve is closed (see FIG. 1).

[0047] [Second embodiment] A motor-operated valve according to a second embodiment of the present invention will be described with reference to Figures 5 to 8. In the description of this embodiment, the same or corresponding components as those in the first embodiment are designated by the same reference numerals, and redundant description will be omitted, with the focus being on the differences.

[0048] 5 to 8, the motor-operated valve 61 according to this embodiment includes an assembly (gear device assembly) 21 including a gear device 22, as in the first embodiment, but is provided with a rotation detection means that detects the rotation of the screw drive member 45, utilizing the space between the gear device 22 and the transmission mechanism 43. In addition, since the rotation detection means is provided, in this embodiment, the gear case 23 has a longer vertical dimension than in the first embodiment, and the gear case 23 has a shape in which the peripheral wall extends downward.

[0049] Specifically, the rotation detection means comprises a disk-shaped driving permanent magnet 62 fixed to the screw drive member 45 so as to be positioned at the lower end inside the gear case 23, a ring-shaped driven permanent magnet 63 positioned outside the lower outer periphery of the gear case 23, and a magnetic sensor 64 that detects the rotation of the driven permanent magnet 63.

[0050] The drive permanent magnet 62 extends horizontally outward from the outer peripheral surface of the screw drive member 45 in a flange-like shape and rotates together with the screw drive member 45. The drive permanent magnet 62 also has semicircular arc portions 62a and 62b defined by a diameter (see FIG. 7 ). One north pole and one south pole are sequentially arranged from the inside to the outside in the radial direction in one semicircular arc portion 62a, and one south pole and one north pole are sequentially arranged from the inside to the outside in the other semicircular arc portion 62b. In this embodiment, the screw drive member 45 includes a shaft portion 45c between the male thread portion 45a and the plate-shaped portion 45b for fixing the drive permanent magnet 62. As a result, the screw drive member 45 of this embodiment has a longer overall length in the vertical direction than that of the first embodiment.

[0051] The driven permanent magnet 63 is coupled to the driving permanent magnet 62 by a magnetic coupling that transmits torque using the attractive force of the permanent magnets, and receives rotational force from the driving permanent magnet 62 to rotate together with the driving permanent magnet 62. For this reason, the driven permanent magnet 63 has the following structure.

[0052] The driven permanent magnet 63 has a ring shape and semicircular arc portions 63a and 63b defined by a diameter. One north pole and one south pole are arranged in order from the inside to the outside in the radial direction in one semicircular arc portion 63a, and one south pole and one north pole are arranged in order from the inside to the outside in the radial direction in the other semicircular arc portion 63b. The north pole of the drive permanent magnet 62 and the south pole of the driven permanent magnet 63 face each other with the circumferential wall of the gear case 23 in between, and the south pole of the drive permanent magnet 62 and the north pole of the driven permanent magnet 63 face each other with the circumferential wall of the gear case 23 in between, thereby forming a magnetic coupling between the drive permanent magnet 62 and the driven permanent magnet 63.

[0053] Furthermore, in order to support the driven permanent magnet 63 rotatably and slidably on the outer peripheral surface of the gear case 23, the following support structure is provided.

[0054] A ring-shaped protrusion 65 (extending around the entire circumference of the gear case 23) is formed at the lower end of the peripheral wall of the gear case 23 by protruding the peripheral wall outward. In addition, a recessed groove 66 (extending around the entire circumference of the inner peripheral surface of the driven permanent magnet 63) into which the protrusion 65 can be fitted is formed on the inner peripheral surface of the driven permanent magnet 63. These protrusions 65 and recessed grooves 66 enable the driven permanent magnet 63 to be slidably and rotatably supported on the outer peripheral surface of the gear case 23 without falling off (for example, falling downward) from the gear case 23.

[0055] The driving permanent magnet 62 fixed to the screw driving member 45 moves up and down while rotating together with the screw driving member 45 in accordance with the up and down movement of the screw driving member 45 (opening and closing of the valve). However, by making the up and down dimension of the driven permanent magnet 63 larger than that of the driving permanent magnet 62, even if the driving permanent magnet 62 moves up and down, the driving permanent magnet 62 does not move out of the up and down range of the driven permanent magnet 63 (a state facing the driven permanent magnet 63), and the magnetic coupling between the driving permanent magnet 62 and the driven permanent magnet 63 is not released.

[0056] The magnetic sensor 64 is a rotation angle sensor that outputs a signal corresponding to the rotation angle of the magnetic field, and is disposed outside the can 42 so as to face radially the outer circumferential surface of the driven permanent magnet 63 across the peripheral wall of the can 42. The magnetic sensor 64 detects the magnetism of the driven permanent magnet 63 and outputs a signal corresponding to the rotation angle of the driven permanent magnet 63. This makes it possible to detect the rotational displacement of the screw drive member 45, and according to this embodiment, it is possible to more accurately detect the valve opening (the distance between the valve disc 18 and the valve seat 17).

[0057] Other configurations and operations of the motor-operated valve 61 according to this embodiment are similar to those of the motor-operated valve 11 according to the first embodiment.

[0058] DESCRIPTION OF SYMBOLS 11, 61 Motor-operated valve 12 Valve body 13 Valve chamber 14 Inlet pipe (first flow path) 15 Outlet pipe (second flow path) 16 Orifice 17 Valve seat 18 Valve body 18a Valve body body portion 18b Valve shaft portion 19 Valve body support member 20 Strainer 21 Gear device assembly (assembly) 22 Gear device (paradox planetary gear reduction mechanism) 23 Gear case 24 Rotor 25 Rotor member 26 Sun gear member 27 Central shaft 28 Support member 29 Sun gear 30 Output gear 31 Carrier 32 Shaft 33 Planetary gear 34 Ring gear (internal tooth fixed gear) 35 Internal tooth gear 36 Output shaft 36a Fitting groove 37 Output shaft guide member (guide portion) 37a Through hole of output shaft guide member 38 Convex portion (engaging convex portion) 39 Concave portion (engaging concave portion) 40 Connecting member 40a Large diameter hole 40b Small diameter hole 41 Base plate 42 Can 43 Transmission mechanism (feed screw mechanism) 44 Bearing member 44a Female thread portion 45 Screw drive member 45a Male thread portion 45b Plate-shaped portion 45c Shaft portion (shaft portion for fixing drive permanent magnet) 46 Ball-shaped joint 47 Ball 48 Ball seat 49 Spring receiving member 49a Fitting hole (lower surface fitting hole) 49b Fitting hole (upper surface fitting hole) 50 Compression coil spring 51 Electric motor 52 Stator 53 Yoke 54 Bobbin 55 Coil 56 Mold cover 62 Drive permanent magnet 62a, 62b, 63a, 63b Semicircular arc portion 63 Driven permanent magnet 64 Magnetic sensor 65 Protrusion 66 Groove

Claims

1. An electric valve comprising: a valve body having a valve chamber therein; a first flow path communicating with the valve chamber; a second flow path communicating with the valve chamber; an orifice formed between the first flow path and the second flow path; a valve disc that moves toward and away from the orifice to change the opening of the orifice; a rotor constituting an electric motor that drives the valve disc; a gear device that reduces the rotation of the rotor; an output shaft that outputs the rotation reduced by the gear device; a transmission mechanism that converts the rotation of the output shaft into linear motion and transmits it to the valve disc; a cylindrical gear case that houses the gear device; and a guide section that rotatably supports the output shaft, wherein the output shaft, the guide section and the gear device are supported by the gear case.

2. The motor-operated valve according to claim 1, wherein the gear device, the gear case, the output shaft, the guide portion and the rotor are unitized as a gear device assembly.

3. An electric valve as claimed in claim 1 or 2, comprising an engagement recess on one of the inner peripheral surface of the gear case and the outer peripheral surface of the guide section, and an engagement protrusion on the other of the inner peripheral surface of the gear case and the outer peripheral surface of the guide section that fits into the engagement recess to prevent rotation of the guide section.

4. The motor-operated valve according to claim 1 or 2, wherein the guide portion is provided in the gear case by insert molding.

5. The electric valve according to claim 1 or 2, wherein the transmission mechanism includes a screw drive member which rotates in response to rotation of the output shaft and is movable back and forth relative to the output shaft and has a male threaded portion on its outer peripheral surface, and a bearing member which has a female threaded portion which screws into the male threaded portion of the screw drive member; and the electric valve further includes a driving permanent magnet which is housed in the lower part of the gear case and fixed to the screw drive member so as to rotate together with the screw drive member, a driven permanent magnet which is coupled to the driving permanent magnet by a magnetic coupling and is arranged on the outside of the outer peripheral surface of the lower part of the gear case so that a rotational force is transmitted from the driving permanent magnet, and a magnetic sensor which detects the rotation of the driven permanent magnet.

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