Electric valve

Abstract

In the present invention, an electric valve comprises: a reduction mechanism 46 that reduces the rotation of an electric motor 31 that drives a valve body 17, and a transmission mechanism 53 that converts rotary motion into linear motion and transmits the linear motion to the valve body. The transmission mechanism has a rotary lifting shaft 48 that connects a first feed screw mechanism 54 and a second feed screw mechanism 55 that have mutually different screw directions. The first feed screw mechanism transmits the rotary motion outputted from the reduction mechanism to the second feed screw mechanism via the rotary lifting shaft, and also converts the rotary motion outputted from the reduction mechanism into linear motion and transmits the linear motion to the second feed screw mechanism via the rotary lifting shaft. The second feed screw mechanism converts the rotary motion transmitted from the first feed screw mechanism via the rotary lifting shaft into linear motion and transmits the linear motion to the valve body, and also transmits the linear motion transmitted from the first feed screw mechanism to the valve body via the rotary lifting shaft.

Description

Electric valve

[0001] The present invention relates to an electric valve, and more particularly to a valve structure that improves the valve element lift amount of a gear-type electric valve.

[0002] BACKGROUND ART Electric valves that use an electric motor such as a stepping motor to control the valve opening have conventionally been used in refrigeration cycle devices equipped with a refrigerant circuit, such as air conditioners and refrigerators / freezers.

[0003] One such motor-operated valve is a gear-type motor-operated valve. A gear-type motor-operated valve generally includes a valve body having an internal valve chamber and flow paths (inflow and outflow paths) for allowing refrigerant to flow in and out of the valve chamber, a valve element that moves up and down within the valve chamber to open and close the flow paths or adjust the degree of opening, an electric motor that drives the valve element, a speed reduction mechanism that reduces the speed of the motor, and a transmission mechanism that converts the reduced rotational motion into linear motion and transmits it to the valve element.

[0004] Further, the following Patent Document 1 discloses such an electrically operated valve.

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-130271

[0006] However, conventional motor-operated valves have difficulty in increasing the valve lift (amount of elevation change) and increasing the valve capacity. Increasing the capacity of a motor-operated valve requires structural changes and enlargement of the motor and reduction mechanism that drive the valve, which increases manufacturing costs and makes it difficult to meet the recent demand for miniaturization of motor-operated valves.

[0007] Furthermore, the above-mentioned problems cannot be solved by the invention described in Patent Document 1.

[0008] Therefore, an object of the present invention is to make it possible to increase the capacity of an electric valve (increase the valve element lift) without requiring structural changes or increases in the size of the electric motor or reduction mechanism.

[0009] To solve the above problems and achieve the object, a first aspect of the present invention provides a motor-operated valve including a valve body having an internal valve chamber communicating with an inlet passage for introducing a fluid and an outlet passage for discharging the fluid, a valve element that moves toward and away from a valve seat formed within the valve chamber, an electric motor that drives the valve element, a speed reduction mechanism that reduces the rotational speed of the electric motor, and a transmission mechanism that includes a first feed screw mechanism and a second feed screw mechanism with opposite thread orientations (i.e., one is a right-hand thread and the other is a reverse-hand thread) and converts the rotational motion reduced by the speed reduction mechanism into linear motion and transmits it to the valve element. The transmission mechanism also includes a rotary elevating shaft that extends to connect the first feed screw mechanism and the second feed screw mechanism, and includes a first threaded portion that constitutes the first feed screw mechanism at one end and a second threaded portion that constitutes the second feed screw mechanism at the other end.

[0010] Furthermore, the first feed screw mechanism transmits the rotational motion output from the reduction mechanism to the second feed screw mechanism via the rotary elevating shaft, and converts the rotational motion output from the reduction mechanism into linear motion and transmits the linear motion to the second feed screw mechanism via the rotary elevating shaft. Furthermore, the second feed screw mechanism converts the rotational motion transmitted from the first feed screw mechanism via the rotary elevating shaft into linear motion and transmits it to the valve disc, and transmits the linear motion transmitted from the first feed screw mechanism to the valve disc via the rotary elevating shaft.

[0011] In conventional motor-operated valves, the rotational motion output from the reduction mechanism is generally converted into linear motion by a feed screw mechanism (corresponding to the first feed screw mechanism of the first invention) provided at the output section of the reduction mechanism, and transmitted to the valve body.

[0012] In contrast, the motor-operated valve according to the first aspect of the invention (the second aspect described below also provides the same effects as the first aspect, and therefore these two aspects are collectively referred to as "the present invention") has two feed screw mechanisms between the speed reduction mechanism and the valve disc, i.e., a first feed screw mechanism located on the speed reduction mechanism side, and a second feed screw mechanism located on the valve disc side. Therefore, with the motor-operated valve according to the present invention, in addition to the linear motion that has conventionally been transmitted to the valve disc, linear motion generated (converted) by the second feed screw mechanism is applied to the valve disc, making it possible to obtain a larger valve disc lift amount than conventionally.

[0013] In addition, in the motor-operated valve according to the present invention, the screw directions of the first and second feed screw mechanisms are configured to be opposite to each other so that the two feed screw mechanisms (first and second feed screw mechanisms) can convert rotational motion into linear motion in one direction additively rather than canceling each other out. In other words, the first threaded portion formed at one end of the rotary-elevating shaft and the second threaded portion formed at the other end have thread directions opposite to each other (one is a right-hand thread and the other is a reverse-hand thread). More specifically, if the first feed screw mechanism (first threaded portion) has a right-hand thread (positive-hand thread), the second feed screw mechanism (second threaded portion) has a left-hand thread (reverse-hand thread), and if the first feed screw mechanism (first threaded portion) has a left-hand thread (reverse-hand thread), the second feed screw mechanism (second threaded portion) has a right-hand thread (positive-hand thread).

[0014] Therefore, if the axial direction of the electric valve is defined as the direction from the valve body to the electric motor (reduction mechanism) as "up" and the direction from the electric motor (reduction mechanism) to the valve body as "down," then, for example, when the rotor of the electric motor rotates and rotational motion in a first rotational direction is output from the reduction mechanism, an upward linear motion is generated by the first feed screw mechanism, and an upward linear motion is also generated by the second feed screw mechanism, and these two upward linear motions are added together to obtain a larger lift amount than in the conventional case (when only the first feed screw mechanism is provided).

[0015] Furthermore, when the rotor of the electric motor rotates in the opposite direction to the above and a rotational motion in a second rotational direction opposite to the first rotational direction is output from the reduction mechanism, a downward linear motion is generated by the first feed screw mechanism and a downward linear motion is also generated by the second feed screw mechanism, and the valve body descends by the sum of these two downward linear motions (the lift amount during the above-mentioned rise).

[0016] In one aspect of the first invention, the screw pitch of the second feed screw mechanism is set to be larger than the screw pitch of the first feed screw mechanism. According to this aspect, the second feed screw mechanism can generate a larger linear motion (larger than the linear motion generated by the first feed screw mechanism), thereby making it possible to increase the valve element lift.

[0017] On the other hand, the first feed screw mechanism may have a structure similar to that of a conventional feed screw mechanism, thereby avoiding the need to modify or increase the size of the electric motor and reduction mechanism, including the first feed screw mechanism. Therefore, according to the present invention, an electric valve with a large valve element lift amount can be constructed using an existing (conventional) electric motor and reduction mechanism. Furthermore, according to the present invention, as exemplified in the following embodiments, a gate valve (sluice valve), which requires a relatively large valve element lift amount, and a flow control valve, which requires precise lift amount control, can be manufactured using a common drive unit (electric motor and reduction mechanism) by appropriately adjusting (changing) the thread pitch and number of threads of the second feed screw mechanism. This enables the overall manufacturing cost of various electric valves to be reduced. Furthermore, the above-mentioned effects can also be obtained by the second invention described below.

[0018] A motor-operated valve according to a second aspect of the present invention includes a valve body having an internal valve chamber communicating with an inlet passage for inflow of a fluid and an outlet passage for outflow of the fluid, a valve element that moves toward and away from a valve seat formed within the valve chamber, an electric motor that drives the valve element, a speed reduction mechanism that reduces the rotational speed of the electric motor, and a transmission mechanism that has a first feed screw mechanism and a second feed screw mechanism with threads that are opposite in orientation (one being a right-handed thread and the other being a reverse-handed thread) and converts the rotational motion reduced by the speed reduction mechanism into linear motion and transmits it to the valve element. The transmission mechanism also includes a rotary elevating shaft that extends to connect the first feed screw mechanism and the second feed screw mechanism, and includes a first threaded portion that constitutes the first feed screw mechanism at one end and a second threaded portion that constitutes the second feed screw mechanism at the other end.

[0019] Furthermore, the first feed screw mechanism transmits the rotational motion output from the reduction mechanism to the second feed screw mechanism via the rotary elevating shaft, and converts the rotational motion output from the reduction mechanism into linear motion and transmits the linear motion to the second feed screw mechanism via the rotary elevating shaft. Furthermore, the second feed screw mechanism converts the rotational motion transmitted from the first feed screw mechanism via the rotary elevating shaft into linear motion and transmits it to the valve disc, and transmits the linear motion transmitted from the first feed screw mechanism to the valve disc via the rotary elevating shaft.

[0020] In one aspect of the second invention, the number of threads of the second feed screw mechanism is made greater than the number of threads of the first feed screw mechanism. That is, in the motor-operated valve according to one aspect of the second invention, instead of the configuration in one aspect of the first invention in which "the screw pitch of the second feed screw mechanism is made greater than the screw pitch of the first feed screw mechanism," the number of threads of the second feed screw mechanism is made greater than the number of threads of the first feed screw mechanism. By increasing the number of threads in this way, it is possible to increase the linear motion (i.e., the lift amount of the valve disc) generated by the second feed screw mechanism.

[0021] Furthermore, it is possible to have both the features of one aspect of the first invention (configuration related to thread pitch) and the features of one aspect of the second invention (configuration related to the number of threads) (i.e., in an electric valve of one aspect of the second invention, the thread pitch of the second feed screw mechanism is made larger than the thread pitch of the first feed screw mechanism), and such an electric valve can further increase the valve body lift amount.

[0022] According to the present invention, the valve element lift amount can be increased without requiring structural changes or increases in size of the electric motor or reduction mechanism, thereby enabling the capacity of the motor-operated valve to be increased.

[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 vertical cross-sectional view showing a motor-operated valve according to a first embodiment of the present invention in a closed state. FIG. 2 is a vertical cross-sectional view showing a motor-operated valve according to the first embodiment in an open (fully open) state. FIG. 3 is a perspective view showing a valve body of the motor-operated valve according to the first embodiment. FIG. 4 is a vertical cross-sectional view showing a motor-operated valve according to a second embodiment of the present invention in a closed state. FIG. 5 is a vertical cross-sectional view showing a motor-operated valve according to the second embodiment in an open (fully open) state. FIG. 6 is a vertical cross-sectional view showing a motor-operated valve according to a third embodiment of the present invention in a closed state. FIG. 7 is a vertical cross-sectional view showing a motor-operated valve according to the third embodiment in an open (fully open) state. FIG. 8 is a vertical cross-sectional view showing a motor-operated valve according to a fourth embodiment of the present invention in a closed state. FIG. 9 is a vertical cross-sectional view showing a motor-operated valve according to the fourth embodiment in an open (fully open) state.

[0025] A motor-operated valve according to an embodiment of the present invention will be described with reference to Figures 1 to 9. Each figure appropriately displays two-dimensional or three-dimensional coordinates that are orthogonal to each other, representing the up-down, left-right, and front-to-back directions, and the following description will be based on these directions. However, the motor-operated valve of the present invention and each embodiment can be used in various orientations, and the directions are used for the sake of convenience of explanation, and the configuration of each part of the present invention is not limited by these directions. Furthermore, although the terms "vertical" and "horizontal" are used, the vertical direction coincides with the up-down direction, and the direction perpendicular to the vertical direction is the horizontal direction, which includes the left-right and front-to-back directions.

[0026] First Embodiment A motor-operated valve 11 according to a first embodiment of the present invention is a gate valve suitable for use in opening and closing a refrigerant flow path in a refrigeration cycle device such as an air conditioner.

[0027] As shown in Figures 1 to 3, the gate valve 11 comprises a valve body 12 having a valve chamber 13 therein and an inlet passage 15 for allowing a refrigerant to flow into the valve chamber 13 and an outlet passage 16 for allowing the refrigerant to flow out of the valve chamber 13; a valve seat 14 formed within the valve chamber 13; a valve element 17 that moves back and forth (up and down) relative to the valve seat 14 to open and close the refrigerant flow path; an electric motor 31 that drives the valve element 17; a speed reduction mechanism (paradox planetary gear speed reduction mechanism) 46 that reduces the rotation of the electric motor 31; a transmission mechanism 53 that includes a rotary elevating shaft 48 and converts the rotational motion reduced by the speed reduction mechanism 46 into linear motion and transmits it to the valve element 17; a can (sealed container) 25 that has a cylindrical shape with no bottom and a lid (an open bottom and a closed top) and forms a sealed space on the upper surface of the valve body 12; and a connecting member 19 that connects the valve body 12 and the can 25. As will be described in detail later, the transmission mechanism 53 has two feed screw mechanisms, namely, a first feed screw mechanism 54 provided on the reduction mechanism 53 side and a second feed screw mechanism 55 provided on the valve body 17 side.

[0028] The valve chamber 13 is formed in the lower center of the valve body 12, and an inlet channel 15 and an outlet channel 16 extend horizontally on either side of the valve chamber 13. That is, the inlet channel 15 extends horizontally from the right side surface of the valve body 12 to the valve chamber 13 and opens onto the right inner side surface of the valve chamber 13 (the opening 15a of this inlet channel 15 into the valve chamber 13 is referred to as the "inlet port").

[0029] On the other hand, the outflow passage 16 extends horizontally from the left side surface of the valve body 12 to the valve chamber 13 and opens into the left inside surface of the valve chamber 13 (the opening 16a of this outflow passage 16 into the valve chamber 13 is referred to as the "outflow port"). The right inside surface of the valve chamber 13 to which the inflow passage 15 opens (particularly the wall surface around the inflow port 15a) and the left inside surface of the valve chamber 13 to which the outflow passage 16 opens (particularly the wall surface around the outflow port 16a) form the valve seat 14 with which the valve disc 17 comes into contact and separates (abuts and separates). Furthermore, both inside surfaces (the left and right inside surfaces) of the valve chamber 13 are tapered, with the distance between them (the left and right inside surfaces) narrowing as they extend downward.

[0030] The valve disc 17 has a block-shaped valve disc main body 17a having a substantially rectangular parallelepiped shape and a cylindrical columnar portion 17b rising vertically upward from the upper surface of the valve disc main body 17a. Both side surfaces (left and right sides) of the valve disc main body 17a are tapered inclined surfaces that correspond to the inner surfaces of the valve chamber 13, with the distance between the left and right sides narrowing as they extend downward. When the valve is closed, the valve disc 17 is wedged into the valve chamber 13, with the left side surface of the valve disc main body 17a coming into close contact with the left inner surface of the valve chamber 13 and the right side surface of the valve disc main body 17a coming into close contact with the right inner surface of the valve chamber 13, thereby blocking the inlet 15a and the outlet 16a.

[0031] Even in the fully opened state (see FIG. 2 ) at its highest position, the lower end of the valve disc 17 is located between the inner surfaces of the valve chamber 13 (in other words, the lower end of the valve disc 17 is located vertically lower than the upper ends of the inner surfaces of the valve chamber 13). Therefore, the valve disc 17 is always restricted by the inner surfaces of the valve chamber 13 during its lifting and lowering (even if it rotates somewhat together with the rotary lift shaft 48 when the rotary lift shaft 48 rotates, its rotation is restricted by its contact with the inner surfaces of the valve chamber 13). This prevents the valve disc 17 from rotating together with the rotary lift shaft 48 when the valve is opened, preventing the valve disc 17 from fitting between the inner surfaces of the valve chamber 13 when the valve is closed again, thereby preventing the valve from closing.

[0032] The columnar portion 17b supports the valve element 17 on the rotary / elevating shaft 48 and constitutes a second feed screw mechanism 55, which will be described later together with the transmission mechanism 53. Furthermore, an opening 12a (this opening will be referred to as the "connecting opening") that communicates with the valve chamber 13 is formed in the upper surface of the valve body 12, and a connecting member 19 is fixed to this connecting opening 12a so as to close the ceiling (upper surface) of the valve chamber 13.

[0033] The connecting member 19 has a cylindrical fitting portion 20 that fits into the connecting opening 12a formed on the upper surface of the valve body 12, and a cylindrical protrusion 21 that communicates with the fitting portion 20, rises upward from the upper surface of the fitting portion 20, and extends upward from the upper surface of the valve body 12. The connecting member 19 is fixed to the valve body 12 by fitting the fitting portion 20 into the connecting opening 12a, and then screwing a ring-shaped pressing member 23, which has a male thread on its outer surface that screws into a female thread formed on the inner surface of the connecting opening 12a, into the connecting opening 12a.

[0034] The fitting portion 20 has a central hole 20a that passes through its center in the vertical direction, and this central hole 20a has two steps 20b so that the diameter of the hole gradually decreases (in two steps) as it goes upward. When the valve is open (fully open), the upper surface of the columnar portion 17b abuts against the upper step 20b, stopping the valve body 17.

[0035] On the other hand, the protrusion 21 has a step on its outer circumferential surface, and the lower end of the can 25 is joined to this step by, for example, welding via the ring-shaped base member 22. This forms a sealed space including the internal spaces of the valve chamber 13, the connecting member 19 (the fitting portion 20 and the protrusion 21), and the can 25, which are all in communication with each other.

[0036] To prevent the refrigerant from leaking from the sealed space to the outside through the connection opening 12a of the valve body 12, a seal member (O-ring) 24 is provided on the outer peripheral surface of the fitting portion 20 so as to be interposed between the fitting portion 20 and the inner peripheral surface of the connection opening 12a. Also, a seal member (O-ring) 24a is provided on the outer peripheral surface of the protrusion 21 so as to be interposed between the fitting portion 20 and the inner peripheral surface of the leg portion 47a (described later) of the resin molded cover. This seal member 24a prevents moisture and the like from entering the electric motor 31 (resin molded cover 47) from the outside.

[0037] The electric motor 31 is configured as a stepping motor including a stator 32 arranged outside the can 25, a rotor 33 arranged rotatably inside the can 25, and a resin molded cover 47 that covers the can 25 and the stator 32. The resin molded cover 47 has cylindrical legs 47a at its lower end that surround the protrusion 21 of the connecting member 19 at a fixed interval.

[0038] The stator 32 disposed outside the can 25 includes a yoke 36 and a coil 38 wound around a bobbin 37. On the other hand, the rotor 33 disposed inside the can 25 is configured by integrally connecting a cylindrical rotor member 33a made of a magnetic material (permanent magnet) and a sun gear member 39 made of a resin material.

[0039] A rotor support shaft 34 is inserted into the center of the sun gear member 39 , and the upper part of the rotor support shaft 34 is supported by a support member 35 disposed inside the top of the can 25 .

[0040] The sun gear 39a of the sun gear member 39 meshes with a plurality of planetary gears 40 rotatably supported on a shaft 43 provided on a carrier 44 mounted on the bottom surface of the output gear 45. The upper portions of the planetary gears 40 mesh with an annular ring gear (internal fixed gear) 41 attached to the upper portion of a cylindrical gear case 56 fixed to the upper portion of the protruding portion 21 of the connecting member 19. The lower portions of the planetary gears 40 mesh with an internal gear 42 of the annular output gear 45. The number of teeth of the ring gear 41 and the number of teeth of the internal gear 42 of the output gear 45 are slightly different, so that the rotation speed of the sun gear 39a is reduced at a large reduction ratio and transmitted to the output gear 45. Note that these gear mechanisms (sun gear 39a, planetary gears 40, ring gear 41, and output gear 45) constitute a reduction mechanism (paradox planetary gear reduction mechanism) 46 that reduces the rotation speed of the stepping motor 31 described above.

[0041] It should be noted that this embodiment (as well as the embodiments described below) employs a paradox planetary gear reduction mechanism which provides a high reduction ratio and is advantageous for size reduction, but the reduction mechanism 46 in the present invention is not limited to a paradox planetary gear reduction mechanism, and may be another planetary gear reduction mechanism, or may be a gear mechanism other than a planetary gear reduction mechanism.

[0042] A cylindrical threaded bearing 26 is press-fitted into the protruding portion 21 of the connecting member 19. An output gear 45 is in slidable contact with the upper surface of the threaded bearing 26. The upper part of a stepped cylindrical output shaft 29 is press-fitted into the center of the bottom of the output gear 45, and the lower part of the output shaft 29 is rotatably inserted into a fitting hole 27 formed in the center of the upper surface of the threaded bearing 26. The lower end of a rotor support shaft 34 is fitted into the upper part of the output shaft 29 so as to be rotatable relative to the output shaft 29.

[0043] A female threaded portion (referred to as the "first female threaded portion") 28 is formed in the lower center of the screw bearing 26, and a male threaded portion (referred to as the "first male threaded portion" / corresponding to the "first threaded portion" in the present invention) 49 formed on the upper part of the rotary elevating shaft 48 is threadedly engaged with this first female threaded portion 28. The screw bearing 26 (first female threaded portion 28) and the rotary elevating shaft 48 (first male threaded portion 49) constitute a transmission mechanism 53 (first feed screw mechanism 54) that converts the rotational motion supplied from the electric motor 31 via the reduction mechanism 46 into linear motion in the vertical direction and transmits it to the valve element 17.

[0044] The rotating and lifting shaft 48 is a rod-shaped member that extends vertically in the up and down direction along the central axis A of the check valve 11 from the center of the screw bearing 26 to the valve body 17, and has a cylindrical portion (referred to as the "first cylindrical portion") located at the upper part of the rod-shaped member and having the first male threaded portion 49 formed on its outer surface, a cylindrical portion (referred to as the "second cylindrical portion") located at the lower end of the rod-shaped member and having a male threaded portion (referred to as the "second male threaded portion" / corresponding to the "second threaded portion" in this invention) 50 formed on its outer surface, a connecting portion 51 that connects the first cylindrical portion and the second cylindrical portion, and a flat screwdriver-shaped plate-shaped portion 52 that stands vertically upward from the top surface of the first cylindrical portion.

[0045] Here, the output gear 45 rotates at a fixed position in the vertical direction without moving up and down, and a flat screwdriver-shaped plate-like portion 52 provided at the upper end of the rotary lift shaft 48 is inserted into a slit-shaped fitting groove 30 provided at the lower end of the output shaft 29 connected to the output gear 45, thereby transmitting the rotational motion of the output gear 45 to the rotary lift shaft 48. The rotary lift shaft 48 receives this rotational motion and rotates together with the output shaft 29, and at the same time, the plate-like portion 52 slides up and down within the fitting groove 30 of the output shaft 29, causing linear vertical motion by the first feed screw mechanism 54. In other words, when the output gear 45 (rotor 33) rotates, the rotary lift shaft 48 moves linearly up and down while rotating, even though the output gear 45 does not move up and down.

[0046] The linear motion of the rotary lift shaft 48 is transmitted to the valve element 17. The valve element 17 is provided at the lower end of the rotary lift shaft 48. Specifically, the columnar portion 17b of the valve element 17 has a threaded hole that passes through the center in the vertical direction. This threaded hole has a female thread (referred to as the "second female thread portion") 18 on its inner circumferential surface, which screws into the second male thread portion 50 formed at the lower end of the rotary lift shaft 48.

[0047] Furthermore, a through-hole 17c is formed in the valve body main body 17a, which passes through the valve body main body 17a in the vertical direction, following (so as to communicate with) the screw hole (second female thread portion) 18 and has a larger diameter than the screw hole 18. Therefore, in this embodiment, the valve body 17 has a hole formed by the screw hole 18 and the through-hole 17c, which are connected to each other, that passes through the entire valve body in the vertical direction. Therefore, a valve body structure having such a hole makes it easier to form the screw hole (second female thread portion) 18 during manufacturing, and also makes it possible to discharge and remove all cutting chips generated during the thread cutting process through the through-hole 17c.

[0048] To install the valve element 17 on the rotary lift shaft 48, the lower end of the rotary lift shaft 48 is screwed into the columnar portion 17b while being threaded into the second female thread portion 18. This allows the valve element 17 to be supported on the lower end of the rotary lift shaft 48. Therefore, the valve element 17 and the rotary lift shaft 48 are capable of rotating relative to each other.

[0049] However, as described above, the valve disc 17 is always restricted in its rotational direction (movement limited) by both inner surfaces of the valve chamber 13, so that even if the rotary lift shaft 48 rotates, the rotation of the valve disc 17 is restricted and its attitude (position in the rotational direction) is maintained. Therefore, when the rotary lift shaft 48 rotates in response to the rotation of the output shaft 29, the valve disc 17 rotates relative to the rotary lift shaft 48, and the feed screw action of the second male thread portion 50 of the rotary lift shaft 48 and the second female thread portion 18 of the valve disc 17, which are threadedly engaged with each other, makes it possible to move the valve disc 17 up and down relative to the rotary lift shaft 48.

[0050] The second female threaded portion 18 of the valve body 17 and the second male threaded portion 50 at the lower end of the rotary lift shaft 48 constitute a transmission mechanism 53 (second feed screw mechanism 55) that converts the rotational motion supplied from the electric motor 31 via the reduction mechanism 46 and the rotary lift shaft 48 into linear motion in the vertical direction and transmits it to the valve body 17.

[0051] In addition, in this embodiment, the central axes A of the columnar portion 17b of the valve body 17, the rotary lift shaft 48, the screw bearing 26, the output shaft 29 and the rotor support shaft 34 coincide with the rotation axis of the rotor 33 and the axis A of the electric valve 11, which extends vertically in the up-down direction.

[0052] Furthermore, the check valve 11 of this embodiment has the following characteristic configurations (1) to (3) for the above-mentioned feed screw mechanism (first feed screw mechanism 54 and second feed screw mechanism 55), which makes it possible to increase the lift amount of the valve body 17 compared to conventional methods.

[0053] (1) The thread direction of the second feed screw mechanism 55 (second male threaded portion 50 and second female threaded portion 18; the same applies below) is opposite to the thread direction of the first feed screw mechanism 54 (first male threaded portion 49 and first female threaded portion 28; the same applies below). This is so that the two feed screw mechanisms (first feed screw mechanism 54 and second feed screw mechanism 55) can additively convert rotational motion into linear motion in one direction rather than canceling each other out. For example, if the first feed screw mechanism 54 is a right-hand thread, the second feed screw mechanism 55 is a left-hand thread. Also, if the first feed screw mechanism 54 is a left-hand thread, the second feed screw mechanism 55 is a right-hand thread.

[0054] (2) The screw pitch of the second feed screw mechanism 55 is larger than the screw pitch of the first feed screw mechanism 54 .

[0055] (3) The number of threads of the second feed screw mechanism 55 is greater than the number of threads of the first feed screw mechanism 54 .

[0056] The operation of the gate valve 11 according to this embodiment will be described as follows.

[0057] When current is supplied to the stator 32 (coil 38) so that the rotor 33 rotates in one direction from the valve-closed state shown in FIG. 1 , the rotation of the rotor 33 is converted into linear motion by the first feed screw mechanism 54, and the rotary lift shaft 48 is lifted upward together with the valve disc 17. At the same time, the rotation of the rotor 33 is transmitted to the second feed screw mechanism 55 via the rotary lift shaft 48, and this rotation is also converted into linear motion in the second feed screw mechanism 55, so that the valve disc 17 is lifted upward relative to the rotary lift shaft 48. In particular, the second feed screw mechanism 55 has a large lift amount for the valve disc 17 due to the characteristic configurations (2) and (3) related to the screw pitch and number of threads, and the valve disc 17 is lifted upward significantly with the addition of the upward linear motion generated by the first feed screw mechanism 54. As a result, the valve disc main body 17a separates from the valve seat 14, and the refrigerant flowing in from the inlet passage 15 passes through the valve chamber 13 and flows out from the outlet passage 16 (see arrow F in FIG. 2 ).

[0058] On the other hand, when current is supplied to the stator 32 (coil 38) so that the rotor 33 rotates in the opposite direction from the open (fully open) state, the rotation of the rotor 33 is converted into linear motion by the first feed screw mechanism 54 and the second feed screw mechanism 55, and the rotary lift shaft 48 moves downward together with the valve element 17, and the valve element 17 moves downward relative to the rotary lift shaft 48. When the valve element main body 17a abuts against the valve seat 14, the flow path between the inlet channel 15 and the outlet channel 16 is blocked, resulting in a closed valve state (see FIG. 1).

[0059] Second Embodiment A motor-operated valve 61 according to a second embodiment of the present invention will be described with reference to Figures 4 and 5. Note that components identical to or corresponding to those of the motor-operated valve 11 of the first embodiment are designated by the same reference numerals, and redundant description will be omitted, with differences being mainly described (the same applies to the third and fourth embodiments described below).

[0060] As shown in Figures 4 and 5, a motor-operated valve 61 according to the second embodiment of the present invention is a gate valve, similar to the motor-operated valve 11 of the first embodiment, comprising: a valve body 12 having a valve chamber 13, a valve seat 14, an inlet passage 15 and an outlet passage 16; a valve element 17 that moves toward and away from the valve seat 14 to open and close the refrigerant flow path; an electric motor 31 that drives the valve element 17; a speed reduction mechanism (paradox planetary gear speed reduction mechanism) 46 that reduces the rotation of the electric motor 31; a transmission mechanism 53 (first feed screw mechanism 54 and second feed screw mechanism 55) that converts the rotational motion reduced by the speed reduction mechanism 46 into linear motion and transmits it to the valve element 17; a can (sealed container) 25 that forms a sealed space on the upper surface of the valve body 12; and a connecting member 19 that connects the valve body 12 and the can 25. However, the structure of the valve element 17 is different from that of the first embodiment.

[0061] Specifically, the valve body 17 has a block-shaped valve body main body portion 17a and a columnar portion 17b, as in the first embodiment, but while in the first embodiment holes 18, 17c were formed that penetrated the entire valve body from top to bottom, in this embodiment the valve body main body portion 17a does not have a through hole 17c, and the screw hole 18 that forms the second female screw portion is formed so as to extend from the upper surface of the columnar portion 17b to near the lower surface of the valve body main body portion 17a (so as not to reach the lower surface of the valve body main body portion 17a and penetrate the valve body 17).

[0062] As in the first embodiment, when the valve is open (fully open), the upper surface of the columnar portion 17b abuts against the upper step portion 20b of the connecting member 19, stopping the valve element 17. In this abutting state when the valve is open, the central hole 20a of the connecting member 19 (fitting portion 20) is closed by the columnar portion 17b of the valve element 17, blocking communication between the valve chamber 13 and the inside of the can 25. This valve element structure of the present embodiment has the following advantages.

[0063] Foreign matter such as dust or metal fragments may be mixed into the refrigerant, and such foreign matter may interfere with the normal operation of the electric motor 31, the reduction mechanism 46, and the transmission mechanism 53 (first feed screw mechanism 54). In contrast, according to this embodiment, communication between the valve chamber 13 and the interior of the can 25 can be blocked when the valve is open, preventing malfunctions caused by foreign matter in the refrigerant.

[0064] The operation of the gate valve 61 according to this embodiment is similar to that of the gate valve 11 according to the first embodiment.

[0065] Third Embodiment A motor-operated valve according to a third embodiment of the present invention will be described with reference to FIGS. 6 and 7. FIG.

[0066] The motor-operated valve 71 of this embodiment is a flow control valve suitable for use in controlling the flow rate of a refrigerant in a refrigeration cycle device such as an air conditioner.

[0067] As shown in Figures 6 and 7, the flow control valve 71 comprises a valve body 12 having a valve chest 13, an inlet passage 15, and an outlet passage 16, a valve port (orifice) 72 formed between the inlet passage 15 and the valve chest 13, a valve seat 14 formed at the valve chest side end of the valve port 72, a valve element 17 that moves toward and away from the valve seat 14 to control the flow rate of refrigerant passing through, an electric motor 31 that drives the valve element 17, a speed reduction mechanism (paradox planetary gear speed reduction mechanism) 46 that slows down the rotation of the electric motor 31, a transmission mechanism 53 that converts the rotational motion slowed down by the speed reduction mechanism 46 into linear motion and transmits it to the valve element, a can (sealed container) 25 that forms a sealed space on the upper surface of the valve body 12, and a connecting member 73 that connects the valve body 12 and the can 25.

[0068] The transmission mechanism 46 includes a rotary lift shaft 48 as in the second embodiment, and is similar to the first and second embodiments in that it is made up of a first feed screw mechanism 54 (comprising a first male threaded portion 49 formed on the upper part of the rotary lift shaft 48 and a first female threaded portion 28 formed on the screw bearing 26) and a second feed screw mechanism 55 (comprising a second male threaded portion 50 formed on the lower end of the rotary lift shaft 48 and a second female threaded portion 18 formed on the valve body 17), whose threads have opposite directions.

[0069] As in the second embodiment, the valve element 17 has a valve element main body portion 17a that moves toward and away from the valve seat 14, and a cylindrical columnar portion 17b that rises vertically upward from the upper surface of the valve element main body portion 17a. However, in this embodiment, since the valve port 72 has a circular horizontal cross-sectional shape and the valve seat 14 has a ring-shaped planar shape, the valve element main body portion 17a has a disk-like shape (circular horizontal cross-sectional shape) corresponding to these (so that it can seat on the valve seat 14 and close the valve port 72). Furthermore, as in the second embodiment, the screw hole that forms the second female thread portion 18 is formed so as to extend from the upper surface of the columnar portion 17b to near the lower surface of the valve element main body portion 17a (so as not to reach the lower surface of the valve element main body portion 17a and penetrate the valve element 17).

[0070] Furthermore, in this embodiment, the connecting member 73 has the function of guiding the valve element 17. Specifically, unlike the previous embodiments, in this embodiment, the center hole 20a of the fitting portion 20 is straight (without a step portion 20b), and the columnar portion 17b of the valve element 17 is fitted into this center hole 20a so as to be slidable up and down. The valve element 17 moves up and down while being guided by the center hole 20a into which the columnar portion 17b is fitted.

[0071] In this embodiment, the connecting member 73 has a male thread on its outer surface that screws into a female thread formed in the connecting opening 12a of the valve body 12, and is fixed to the valve body 12 by screwing it into the connecting opening 12a without using the retaining member 23 used in the first and second embodiments (the same applies to the connecting member 82 of the fourth embodiment described later).

[0072] The outer periphery of the columnar portion 17b of the valve element 17 is cylindrical and D-shaped (or may be rectangular or other) in horizontal cross section, and the central hole 20a of the fitting portion 20 is also D-shaped (or may be rectangular or other) in horizontal cross section, with the flat portions acting as sliding surfaces to prevent rotation of the valve element 17 around the axis A. Note that a motor-operated valve 81 of a fourth embodiment, which will be described later, also has a similar structure to prevent rotation of the valve element 17 around the axis A.

[0073] The operation of the flow control valve 71 according to this embodiment will be described as follows.

[0074] When current is supplied to the stator 32 (coil 38) so that the rotor 33 rotates in one direction from the closed valve state shown in Figure 6, the rotation of the rotor 33 is converted into linear motion by the first feed screw mechanism 54, and the rotary lift shaft 48 is pulled upward together with the valve element 17. At the same time, the rotation of the rotor 33 is transmitted to the second feed screw mechanism 55 via the rotary lift shaft 48, and this rotation is also converted into linear motion in the second feed screw mechanism 55, so that the valve element 17 is pulled upward relative to the rotary lift shaft 48. The lift amount (amount of upward movement) of the valve element 17 is the sum of the lift amounts generated by the first feed screw mechanism 54 and the second feed screw mechanism 55, and as a result, the valve element main body 17a separates from the valve seat 14, and the valve is opened so that refrigerant flowing in from the inlet passage 15 passes through the valve port 72 and the valve chamber 13 and flows out from the outlet passage 16 (see arrow F in Figure 7). The amount of refrigerant passing through (refrigerant flow rate) in this open state can be adjusted by the amount of rotation of the rotor 33 .

[0075] On the other hand, when current is supplied to the stator 32 (coil 38) so that the rotor 33 rotates in the opposite direction from the open valve state, the rotation of the rotor 33 is converted into linear motion by the first feed screw mechanism 54 and the second feed screw mechanism 55, causing the rotary lift shaft 48 to move downward together with the valve element 17, and the valve element 17 to move downward relative to the rotary lift shaft 48. When the valve element main body 17a abuts against the valve seat 14, the flow path between the inlet channel 15 and the outlet channel 16 is blocked, resulting in a closed valve state (see FIG. 6).

[0076] Fourth Embodiment A motor-operated valve according to a fourth embodiment of the present invention will be described with reference to FIGS. 8 and 9. FIG.

[0077] As shown in Figures 8 and 9, the motor-operated valve 81 of this embodiment is a flow control valve that controls the flow rate of refrigerant by including the electric motor 31, the speed reduction mechanism 46, and the transmission mechanism 53 (first feed screw mechanism 54 and second feed screw mechanism 55) as in the third embodiment, but has improved valve opening performance by including a structure that cancels the pressure difference between above and below the valve body.

[0078] Specifically, in this embodiment, a cylindrical valve element guide portion 83 is formed in the fitting portion 20 of the connecting member 82, and the valve element 17 is slidably housed in this valve element guide portion 83. The valve element 17 has a valve element main body portion 17a that moves toward and away from the valve seat 14 and a columnar portion 17b that rises upward from the upper surface of the valve element main body portion 17a. When the valve element main body portion 17a descends, it protrudes from the lower internal space of the valve element guide portion 83 through an opening on the lower surface of the valve element guide portion 83 toward the valve seat 14, and when it ascends, it retracts into the lower internal space of the valve element guide portion 83 through the opening on the lower surface. Note that even when the amount of protrusion of the valve element main body portion 17a from the valve element guide portion 83 is maximized (i.e., when the valve is closed), the upper end of the valve element main body portion 17a, on which a seal member 86 (described later) is located, is positioned within the lower internal space of the valve element guide portion 83.

[0079] A back pressure chamber 84 is formed above the valve body main body 17a, more specifically, within the internal space of the valve body guide portion 83 and on the upper surface side of the valve body main body 17a (around the lower part of the columnar portion 17b). A pressure equalization path 85 is formed in the valve body 17, connecting the center of the lower surface of the valve body main body 17a (the portion facing the valve port 72 when the valve is closed) with the back pressure chamber 84 and introducing low pressure from the inlet path 15 into the back pressure chamber 84. The pressure equalization path 85 consists of a vertical path 85a that extends from the center of the lower surface of the valve body main body 17a upward inside the valve body 17 to the lower part of the columnar portion 17b, and a horizontal path 85b that communicates with the vertical path 85a, extends horizontally at the lower part of the columnar portion 17b, and opens to the back pressure chamber 84. The second female thread portion 18 is formed in the upper part of the columnar portion 17b (above the horizontal path 85b).

[0080] Furthermore, to prevent communication between the outflow path 16 and the back pressure chamber 84 when the valve is closed, a seal member 86 is provided on the outer peripheral surface of the upper part of the valve body 17a so as to be interposed between the valve body 17a and the inner peripheral surface of the valve body guide 83. This seal member 86 consists of an O-ring 87 and a lip seal 88 with low sliding resistance that is disposed on the outside of the O-ring 87 and makes sliding contact with the inner peripheral surface of the valve body guide 83.

[0081] In this embodiment, the cross-sectional area of ​​the inside of the outer periphery of the columnar portion 17b and the valve body main portion 17a is set to be approximately the same as the cross-sectional area of ​​the valve port 72. Therefore, in the closed state (FIG. 8), the downward force (force in the valve closing direction) and the upward force (force in the valve opening direction) acting on the valve body 17 are balanced, making it possible to more reliably lift the valve body 17 in the closed state and open the valve.

[0082] The operation of the flow control valve 81 according to this embodiment is similar to that of the flow control valve 71 according to the third embodiment, but when the valve element 17 is raised from the closed state (FIG. 8) to open the valve (FIG. 9), the force pushing down on the valve element 17 and the force pushing up on the valve element 17 are balanced as described above due to the function of the differential pressure canceling structure (back pressure chamber 84 and pressure equalizing path 85), so the valve element 17 can be raised and the valve opening operation can be performed more reliably than with the flow control valve 71 according to the third embodiment. Therefore, this embodiment has an advantageous structure, particularly when the differential pressure acting on the valve element increases due to an increase in the capacity of the motor-operated valve.

[0083] A Axis (central axis) F Refrigerant flow 11, 61 Motor-operated valve (gate valve) 71, 81 Motor-operated valve (flow control valve) 12 Valve body 12a Connection opening 13 Valve chamber 14 Valve seat 15 Inflow path 15a Inlet 16 Outflow path 16a Outlet 17 Valve body 17a Valve body body portion 17b Column-shaped portion 17c Through hole 18 Second female thread portion (threaded hole) 19, 73, 82 Connection member 20 Fitting portion 20a Central hole 20b Step portion 21 Protrusion 22 Base member 23 Pressing member 24, 24a Seal member 25 Can (sealed container) 26 Threaded bearing 27 Fitting hole 28 First female thread portion 29 Output shaft 30 Fitting groove 31 Electric motor (stepping motor) 32 Stator 33 Rotor 33a Rotor member 34 Rotor support shaft 35 Support member 36 Yoke 37 Bobbin 38 Coil 39 Sun gear member 39a Sun gear 40 Planet gear 41 Ring gear (internal tooth fixed gear) 42 Internal gear 43 Shaft 44 Carrier 45 Output gear 46 Reduction mechanism (paradox planetary gear reduction mechanism) 47 Resin molded cover 47a Leg portion of resin molded cover 48 Rotation / elevation shaft 49 First male thread portion 50 Second male thread portion 51 Connecting portion 52 Plate-shaped portion 53 Transmission mechanism 54 First feed screw mechanism 55 Second feed screw mechanism 56 Gear case 72 Valve port (orifice) 83 Valve body guide portion 84 Back pressure chamber 85 Pressure equalization path 85a Vertical path 85b Horizontal path 86 Sealing member 87 O-ring 88 Lip seal

Claims

a valve body having an internal valve chamber communicating with an inlet passage for introducing a fluid and an outlet passage for allowing the fluid to flow out; a valve element moving toward and away from a valve seat formed in the valve chamber; an electric motor for driving the valve element; a speed reduction mechanism for decelerating the rotation of the electric motor; and a transmission mechanism having a first feed screw mechanism and a second feed screw mechanism having threads directed in opposite directions, the transmission mechanism converting the rotational motion decelerated by the speed reduction mechanism into linear motion and transmitting the linear motion to the valve element, the transmission mechanism having a rotating elevating shaft extending to connect the first feed screw mechanism and the second feed screw mechanism, the rotating elevating shaft having a first threaded portion constituting the first feed screw mechanism at one end and a second threaded portion constituting the second feed screw mechanism at the other end, the first feed screw mechanism transmitting the rotational motion output from the speed reduction mechanism to the second feed screw mechanism via the rotating elevating shaft, and converting the rotational motion output from the speed reduction mechanism into linear motion and transmitting the linear motion to the second feed screw mechanism via the rotating elevating shaft, the second feed screw mechanism converts the rotational motion transmitted from the first feed screw mechanism via the rotary elevating shaft into linear motion and transmits it to the valve element, and also transmits the linear motion transmitted from the first feed screw mechanism via the rotary elevating shaft to the valve element.

2. The motor-operated valve according to claim 1, wherein the screw pitch of the second feed screw mechanism is larger than the screw pitch of the first feed screw mechanism.

3. A valve body having an internal valve chamber communicating with an inlet passage for introducing a fluid and an outlet passage for discharging the fluid; a valve element moving toward and away from a valve seat formed in the valve chamber; an electric motor for driving the valve element; a speed reduction mechanism for decelerating the rotation of the electric motor; and a transmission mechanism having a first feed screw mechanism and a second feed screw mechanism having threads directed in opposite directions, the transmission mechanism converting the rotational motion decelerated by the speed reduction mechanism into linear motion and transmitting the linear motion to the valve element, the transmission mechanism having a rotating elevating shaft extending to connect the first feed screw mechanism and the second feed screw mechanism, the rotating elevating shaft having a first threaded portion constituting the first feed screw mechanism at one end and a second threaded portion constituting the second feed screw mechanism at the other end, the first feed screw mechanism transmitting the rotational motion output from the speed reduction mechanism to the second feed screw mechanism via the rotating elevating shaft, and converting the rotational motion output from the speed reduction mechanism into linear motion and transmitting the linear motion to the second feed screw mechanism via the rotating elevating shaft, the second feed screw mechanism converts the rotational motion transmitted from the first feed screw mechanism via the rotary elevating shaft into linear motion and transmits it to the valve element, and also transmits the linear motion transmitted from the first feed screw mechanism via the rotary elevating shaft to the valve element.

4. The motor-operated valve according to claim 3, wherein the number of threads of the second feed screw mechanism is greater than the number of threads of the first feed screw mechanism.

5. The motor-operated valve according to claim 4, wherein the screw pitch of the second feed screw mechanism is larger than the screw pitch of the first feed screw mechanism.

Images