JP7722726B2 - Electric valve and planetary gear reduction mechanism - Google Patents

Description

This disclosure relates to an electric valve and a planetary gear reduction mechanism.

As disclosed in Patent Document 1, a conventional motor-operated valve that opens and closes the valve via an electric motor is known, in which the input rotation of the rotor is slowed down by a planetary gear reduction mechanism and the slowed output rotation is transmitted to a screw mechanism that controls the opening and closing of the valve. Specifically, Patent Document 1 discloses a paradox planetary gear type differential gear mechanism. In a differential gear mechanism, the fixed gear can rotate at a relatively high reduction ratio depending on the difference in the number of teeth between the fixed gear and the output gear.

As another example of a planetary gear reduction mechanism, Patent Document 2 discloses a 3K-type planetary gear device, which, although not an electric valve, has three basic shafts, an input shaft, an output shaft, and a fixed shaft, all of which have the same rotational axis as the central axis of the device.

Patent No. 4936941 Patent No. 6782494

Here, in one planetary gear, the tooth that meshes with the fixed gear is referred to as the "first tooth," and the tooth that meshes with the output gear at a position different from the first tooth is referred to as the "second tooth." In the cases of Patent Documents 1 and 2, the module of the first tooth and the module of the second tooth are the same in one planetary gear.

For this reason, not only the design of the planetary gears, but also the design of other gear elements that mesh with the planetary gears, such as the sun gear, fixed gear, and output gear, is limited by the requirement that the modules of the first and second teeth of the planetary gears be the same. As a result, there is a problem in that the degree of freedom in the design of planetary gear reduction mechanisms, and the degree of freedom in the design of motor-operated valves that use planetary gear reduction mechanisms, is reduced overall.

In light of the above, this disclosure provides a new technology that can improve design freedom in motor-operated valves and planetary gear reduction mechanisms.

The motor-operated valve according to the first aspect comprises: an electric motor; a planetary gear type reduction mechanism having a planetary gear with first teeth to which the input rotation of the electric motor is input and second teeth corresponding to the first teeth and having a module different from that of the first teeth; and an output gear that meshes with the second teeth and outputs output rotation that is reduced from the input rotation; and a valve main body that controls the opening degree of the valve using the output rotation.

In the motor-operated valve according to the first aspect, the planetary gear reduction mechanism can be designed without being restricted by the requirement that the modules of the first and second teeth be the same, thereby improving the design freedom of the motor-operated valve.

In a second aspect, in the motor-operated valve according to the first aspect, the planetary gear reduction mechanism includes a fixed gear provided in the input region and having a number of teeth different from the number of teeth of the output gear, and a sun gear arranged concentrically with the fixed gear, to which the input rotation is input and which meshes with the first teeth of the planetary gear.

In the second aspect, it is possible to realize a paradox planetary gear reduction mechanism, particularly a planetary gear reduction mechanism equipped with a fixed gear and a sun gear.

A third aspect is the motor-operated valve according to the second aspect, in which the root diameter of the fixed gear is 15 mm or less.

The third aspect particularly improves the design freedom of small motor-operated valves in which the root diameter of the fixed gear is 15 mm or less.

The fourth aspect is a motor-operated valve according to any one of the first to third aspects, comprising a valve body having a valve chamber formed therein, a valve seat having an opening formed in a portion of the wall surface of the valve chamber, a valve disc arranged to open and close the opening of the valve seat, a valve stem moving the valve disc toward and away from the valve seat, a cylindrical can attached to the valve body and forming a space between it and the valve body, an excitation device for the electric motor attached to the outer periphery of the can, a permanent magnet rotor assembly rotatably supported inside the can and rotationally driven by the excitation device, and a screw mechanism that converts the output rotation from the planetary gear reduction mechanism into movement of the valve disc toward and away from the valve seat and transmits the rotation to the valve stem, with the rotor assembly and planetary gear reduction mechanism disposed in the space between the valve body and the can.

The fourth aspect allows for particularly improved design freedom for motor-operated valves in which a rotor assembly and a planetary gear reduction mechanism are disposed in the space between the valve body and the can.

In a fifth aspect, in the motor-operated valve according to any one of the first to fourth aspects, the output gear is a cylindrical member with a bottom having a bottom and a wall rising from the periphery of the bottom, and a storage space capable of storing fluid is formed inside the cylindrical member.

Here, for example, by configuring the number of second teeth of the planetary gear to be the same as the number of first teeth, but making the diameter of the pitch circle of the second teeth smaller than the diameter of the pitch circle of the first teeth, and thereby making the module of the second teeth smaller than the module of the first teeth, the number of teeth of the output gear that mesh with the second teeth can be reduced. As a result, the groove width between adjacent teeth on the output gear, in other words, the gap, increases compared to when the number of teeth on the output gear is the same. In the fifth aspect, the volume of fluid that can be stored in the storage space can be increased by the amount of the gap increased. For example, if the fluid to be stored is a lubricating fluid, the volume of lubricating fluid that can be held in the storage space increases, thereby improving the lubricity of the motor-operated valve.

The planetary gear reduction mechanism according to the sixth aspect includes a planetary gear having first teeth to which external input rotation is input, second teeth that correspond to the first teeth and have a module different from that of the first teeth, and an output gear that meshes with the second teeth and outputs output rotation that is reduced from the input rotation.

As with the motor-operated valve according to the first aspect, the planetary gear reduction mechanism according to the sixth aspect is not restricted to the requirement that the modules of the first and second teeth be the same, thereby improving the design freedom of the planetary gear reduction mechanism.

The motor-operated valve disclosed herein provides a new technology that improves design freedom for motor-operated valves and planetary gear reduction mechanisms, as well as a method for assembling a motor-operated valve using this technology.

1 is a cross-sectional view illustrating an embodiment of the motor-operated valve according to the present disclosure, taken along a plane including a central axis that is a rotation axis. FIG. 2 is a partially cutaway perspective view illustrating the inside of a paradox planetary gear reduction mechanism in the motor-operated valve according to the present embodiment. FIG. 4 is a plan view illustrating an input region of the paradox planetary gear reduction mechanism according to the present embodiment. FIG. 4 is a plan view illustrating an output region of the paradox planetary gear reduction mechanism according to the present embodiment. FIG. 2 is a perspective view illustrating a planet gear of the paradox planetary gear type reduction mechanism according to the embodiment. FIG. 2 is a front view illustrating a planet gear of the paradox planetary gear type reduction mechanism according to the embodiment. FIG. 4 is a bottom view illustrating the planet gear of the paradox planetary gear type reduction mechanism according to the embodiment, viewed from the second tooth side.

This embodiment is described below. In the following drawings, identical or similar parts are designated by the same or similar reference numerals. However, the drawings are schematic, and the relationship between thickness and planar dimensions, the thickness ratios of each device and each component, etc. may differ from the actual ones. Therefore, specific thicknesses and dimensions should be determined with reference to the following explanation. Furthermore, there may be parts with different dimensional relationships and ratios between the drawings. Furthermore, unless otherwise specified in the specification, the number of each component element in this disclosure is not limited to one and may be multiple.

<Configuration of the motor-operated valve>
The motor-operated valve according to this embodiment has a basic structure including a drive unit, a reduction mechanism as a gear reducer, a screw mechanism, and a valve body. The drive unit functions as an excitation motor and includes a motor consisting of a stator and a rotor.

The reduction mechanism performs gear deceleration when a rotational driving force is input from the drive unit, and outputs the decelerated rotation. In other words, the reduction mechanism decelerates the input rotation input from the drive unit to form output rotation, and outputs the output rotation to the screw mechanism. The reduction mechanism (reduction device) includes a planetary gear reduction mechanism (planetary gear reduction device).

The screw mechanism converts the reduced rotation, i.e., output rotation, from the reduction mechanism into a displacement in the screw axis direction through screw action and outputs it. The valve body controls the valve opening by moving the valve disc toward and away from the valve seat in response to the displacement output in the screw axis direction of the screw mechanism. Each component will be explained below with reference to Figure 1.

(Drive unit)
As shown in FIG. 1 , the drive section of the motor-operated valve 1 according to this embodiment includes a can 30 , a motor excitation device 2 , and a rotor assembly 50 .

(Can)
The can 30 is a closed-ended cylindrical pressure vessel fixed to the valve body 10. The can 30 is made of a non-magnetic metal material. The lower end of the can 30 in FIG. 1 abuts against the periphery of the receiving member 20 provided on the valve body 10.

The can 30 is fixed to the valve body 10 via a receiving member 20. The valve body 10 has a valve chamber 12 formed in its lower part and an orifice 14 extending downward from the bottom of the valve chamber 12. Refrigerant piping 18A, which communicates with the side of the valve chamber 12, and refrigerant piping 18B, which communicates with the lower end of the orifice 14, are fixed to the valve body 10. The rotor assembly 50, mounted inside the can 30, rotates when a drive signal is supplied to the coil 3 of the motor excitation device 2.

(Motor Exciter)
The motor excitation device 2 is attached to the outside of the can 30 by a mounting fixture 5 formed of a leaf spring in a detachable fit state relative to the can 30. In the motor excitation device 2, a coil 3 constituting the motor stator is molded integrally with resin. The motor excitation device 2 has a resin mold, a coil 3 wound around a bobbin mounted inside the resin mold, and a stator that is excited by passing current through the coil 3, and the coil 3 is connected to an external power source via an electric circuit 4 and lead wires to receive power. The reference numerals of the resin mold in FIG. 1 have been omitted for clarity.

(bearings, shafts)
The bearing 40 has a hat-shaped or disk-shaped cross section with a hole 41 in the center. The bearing 40 is inserted inside the top of the can 30 and is disposed on the inner surface of the can 30. A shaft 42 is inserted into the hole 41 of the bearing 40. A rotor assembly 50, which is a permanent magnet rotor of the stepping motor, is disposed inside the can 30 so as to be rotatable by the shaft 42.

(Rotor assembly)
The rotor assembly 50 is rotatably supported within the can 30. The rotor assembly 50 is a permanent magnet type that is rotationally driven by the motor excitation device 2. The motor excitation device 2 is an excitation device for a stepping motor, which is an example of an electric motor.

The rotor assembly 50 is formed in a cylindrical shape from a plastic material containing a magnetic material, and is molded integrally with the sun gear member 54 located in the center. The sun gear member 54 has a boss (not shown) extending vertically downward in the center. The boss has a through-hole 58 for the shaft 42. The sun gear 56, which is one component of the reduction mechanism 60, is formed on the outside of the boss.

(Gear case)
The gear case 61 is a cylindrical member. The lower part of the gear case 61 is fitted into the upper part of the holder 72. The upper part of the gear case 61 is bent toward the fixed gear 62. The gear case 61 is made of metal or the like.

The bent portion of the gear case 61 comes into contact with the outer surface of the fixed gear 62, which is made of resin or the like. In this embodiment, the fixed gear 62 is fixed to the gear case 61 by crimping. In other words, the fixed gear 62 is locked at the bent portion of the gear case 61. The gear case 61 houses the reduction mechanism 60. Note that the gear case 61 may be included in the reduction mechanism 60.

(Operation of the reduction mechanism)
In the reduction mechanism 60, the sun gear 56 of the rotor assembly 50 functions as an input gear. The planetary gears 65 supported by the carrier 64 mesh with the sun gear 56, and also mesh with the fixed gear 62 (more precisely, a ring gear (fixed-side internal gear) 62A formed on the inner circumferential surface of the fixed gear 62; see FIG. 2 ) and the output gear 66 (more precisely, an output-side internal gear 66D formed on the inner circumferential surface of the output gear 66; see FIG. 2 ). The entire carrier 64 is supported so as to be able to rotate freely on the output gear 66.

The ring gear 62A and the output side internal gear 66D have different numbers of teeth, but are both configured to mesh with the planetary gear 65. To achieve this meshing, the addendum shift coefficients of the ring gear 62A and the output side internal gear 66D are set to appropriate values. When the planetary gear 65 rotates and revolves while meshing with the ring gear 62A of the fixed gear 62, the output gear 66 rotates relative to the fixed gear 62 due to the difference in the number of teeth.

As a result, in the reduction mechanism 60, the input rotation from the sun gear 56 is reduced and output to the output gear 66, resulting in a large reduction ratio of, for example, about 50:1. As a result, the rotation speed of the rotor assembly 50 is reduced, for example, to 1/50, and transmitted to the screw shaft 71 via the output shaft 70. As a result, the screw shaft 71 can rotate at a very small rotation speed. This allows for high-resolution control of the valve opening.

(reduction ratio)
The following describes the reduction ratio when the number of teeth of the output-side internal gear 66D of the output gear 66 is greater than the number of teeth of the ring gear 62A in the reduction mechanism 60. When the sun gear 56 rotates clockwise (CW) together with the rotor assembly 50 due to operation of the motor excitation device 2, the planetary gear 65 meshing with the sun gear 56 and the ring gear 62A rotates counterclockwise (CCW), in other words, revolves around the sun gear 56 while rotating on its own axis.

As a result, the carrier 64 is decelerated and rotates clockwise (CW). The output gear 66, which meshes with the planetary gear 65, is further decelerated and rotates clockwise (CW) based on the difference in the number of teeth between the ring gear 62A (see FIG. 2) and the output-side internal gear 66D (see FIG. 2). When the numbers of teeth of the sun gear 56, planetary gear 65, ring gear 62A of the fixed gear 62, and output-side internal gear 66D of the output gear 66 in the reduction mechanism 60 are Z1, Z2, Z3, and Z4, respectively, the output gear ratio of the output gear 66, i.e., the reduction ratio, is expressed by the following equation (1):

Reduction ratio = [Z4・(Z1+Z3)]/[Z1・(Z4-Z3)] ...(1)
However, Z3 ≠ Z4

The above formula (1) can also be expressed as the following formula (2) by dividing the numerator and denominator on the right side by (Z1·Z4).

Reduction ratio = (1+Z3/Z1)/(1-Z3/Z4)...(2)

The smaller the difference between the number of teeth on the ring gear 62A of the fixed gear 62 and the number of teeth on the output-side internal gear 66D of the output gear 66, the greater the reduction ratio can be. Therefore, when a larger reduction ratio is desired, for example, if there are three planetary gears, the setting can be [Z4 - Z3] = 3. Furthermore, the larger Z3/Z1, the greater the reduction ratio that can be obtained. Therefore, the number of teeth Z1 on the sun gear 56 is reduced, and the number of teeth Z3 on the ring gear 62A, the number of teeth Z4 on the output-side internal gear 66D, and the number of teeth Z2 on the planetary gear 65 are each determined to obtain the required reduction ratio.

For example, when Z1 = 12, Z2 = 18, Z3 = 48, and Z4 = 54 are set, the output gear ratio of the output gear 66 is a large reduction ratio of 1/45. Because the rotation of the rotor assembly 50 is transmitted to the screw shaft 71 at a large reduction ratio of 1/45, it is possible to control the valve opening precisely, i.e., with high resolution.

(output shaft)
1, the output shaft 70 is a cylindrical member having a bottomed first hole 70A that receives the shaft 42 and a second hole 70B (for example, a slot or slit-like groove) formed on the opposite side of the first hole 70A. As shown in FIG. 1, the rotation of the output shaft 70 is transmitted to the shaft 42 by inserting the flat plate-like protrusion 71A of the screw shaft 71 into the second hole 70B.

(piping, holder)
Two pipes 18A, 18B are attached to the valve body 10 in an airtight or liquidtight manner. A holder 72 is provided on the upper side of the valve body 10. In the motor-operated valve 1 according to this embodiment, the valve body 10 and the holder 72 are integrally manufactured using the same material. However, the present disclosure is not limited to this, and the valve body and the holder may be manufactured separately using different materials and then integrated by welding or the like.

The holder 72 is a cylindrical member. The outer diameter of the holder 72 is smaller than the outer diameter of the valve body 10, and the outer edge of the valve body 10 is located radially outward from the outer edge of the holder 72. A shoulder of the valve body 10 is formed at the boundary height between the valve body 10 and the holder 72.

(Receiving member)
The lower surface of a ring-shaped receiving member 20 is welded to the upper surface of the shoulder portion of the valve body 10. The outer portion of the receiving member 20 is located outside the outer edge of the valve body 10.

With the bearing 73 fitted inside the holder 72, the holder 72 and bearing 73 are integrated by press-fitting, crimping, or the like. The gear case 61 is attached to the upper side of the holder 72 in a fitted state. A protrusion 71A is provided on the upper part of the screw shaft 71. The protrusion 71A is inserted into a second hole 70B in the output shaft 70 of the reduction mechanism 60. A ball 74 is fixed to a recess 71B at the bottom of the screw shaft 71. Rotation of the screw shaft 71 is converted into movement along the screw axis direction, which is parallel to the central axis X in Figure 1, and is transmitted to the valve stem 75 via the ball 74.

(Screw mechanism)
The screw mechanism of the motor-operated valve 1 uses a feed screw mechanism to convert the rotation of the output shaft 70 of the speed reduction mechanism 60 into linear motion that moves the valve element 76 toward and away from the valve seat 17, and transmits this motion to the valve stem 75. The screw mechanism of this embodiment includes a screw shaft 71. The screw shaft 71 is threadedly engaged with threads formed on the inner surface of a cylindrical bearing 73. The screw mechanism drives the screw shaft 71.

The bearing may be formed integrally with the holder using the same material. If the bearing and holder are formed integrally, the output gear 66 (output shaft 70) is supported directly by the holder 72.

(Valve body)
The valve body of this embodiment includes a screw shaft 71, a ball 74, a ball receiving member 74A, a valve stem 75, and a valve body 76. The valve body may also include a valve body 10, a valve chamber 12, and an orifice 14.

In the valve body of the motor-operated valve 1, the movement of the screw shaft 71 is transmitted to the valve stem 75 via the ball 74 and ball receiving member 74A. As a result, the valve element 76 attached to the tip of the valve stem 75 moves linearly along the vertical direction (the direction of the central axis X) in Figure 1. This controls the flow path area between the valve element 76 and the orifice 14, thereby regulating the flow rate of the refrigerant. In addition, a spring receiving member 26 is attached across the valve stem 75 and the valve body 10. As will be described later, the spring receiving member 26 functions to support the lower end of the compression coil spring 24 that urges the valve element 76 upward, and also functions as a sliding guide for the valve element 76 as it moves up and down.

(Valve body)
A valve chamber 12 is formed inside the valve body 10, and a valve seat 17 is formed as part of the wall surface that forms the valve chamber 12. An orifice 14 that communicates with the valve chamber 12 is formed in the valve body 10. In addition, a pipe 18A that communicates with the valve chamber 12 and a pipe 18B that communicates with the orifice 14 are attached to the valve body 10 in an airtight or liquidtight manner.

(Valve stem)
A valve element 76 is disposed inside the valve chamber 12. The valve element 76 moves toward and away from the valve seat 17 to open and close an opening formed in the valve seat 17. In other words, the valve element 76 is capable of opening and closing the opening of the valve seat 17. In order to move the valve element 76, a valve rod 75 linked to a screw shaft 71 of the screw mechanism is connected to the valve element 76.

(Spring receiving member)
1, the spring bearing member 26 has a small diameter portion 26A, a large diameter portion 26B located above the small diameter portion 26A and having a larger diameter than the small diameter portion 26A, and a flange-shaped portion 26C extending horizontally from the upper edge of the large diameter portion 26B. A step portion 26D is formed at the boundary between the small diameter portion 26A and the large diameter portion 26B.

The small diameter portion 26A is positioned inside the valve chamber 12. The outer surface of the large diameter portion 26B contacts the inner surface of the valve body 10. The lower surface of the flange portion 26C in FIG. 1 contacts the step at the boundary between the valve body 10 and the holder 72 inside the valve body 10. The upper surface of the flange portion 26C in FIG. 1 contacts the lower surface of the bearing 73. The flange portion 26C is sandwiched between the bearing 73 and the valve body 10, thereby fixing its position inside the valve body 10. The valve stem 75 is slidably inserted inside the spring receiving member 26.

As shown in FIG. 1, the lower part of the side of the valve stem 75 contacts the inner surface of the small diameter portion 26A. A compression coil spring 24 is disposed between the upper part of the side of the valve stem 75 in FIG. 1 and the inner surface of the large diameter portion 26B. The lower winding end of the compression coil spring 24 in FIG. 1 contacts the upper surface of the step portion 26D at the boundary between the small diameter portion 26A and the large diameter portion 26B. The upper winding end of the compression coil spring 24 in FIG. 1 contacts the flange-shaped spring seat 75A provided at the top of the valve stem 75.

The ball receiving member 74A of the ball 74 is inserted and fixed to the upper end of the valve stem 75. As shown in Figure 1, the screw shaft 71 abuts against the top of the ball 74. The ball 74 transmits axial thrust to the valve stem 75 via the screw mechanism.

Figure 1 illustrates a state in which the motor-operated valve 1 is closed, as the output rotation from the reduction mechanism 60 causes the valve stem 75 to descend and the valve element 76 to reach its lowest point. On the other hand, when the output rotation reverses from the state illustrated in Figure 1, the valve stem 75 rises due to the biasing force of the compression coil spring 24, resulting in the motor-operated valve 1 being opened.

(Planetary paradox gear reduction mechanism)
Next, the reduction mechanism 60 according to this embodiment will be described in more detail with reference to Figures 2 to 7. The reduction mechanism 60 according to this embodiment is a paradox planetary gear reduction mechanism. Note that in the present disclosure, the reduction mechanism is not limited to a paradox planetary gear reduction mechanism, and may be another planetary gear reduction mechanism (planetary gear reduction device).

As shown in FIG. 2, in this embodiment, the reduction mechanism 60 can be divided axially into an upper input region R1 and a lower output region R2. The sun gear 56, the first tooth T1 of the planetary gear 65, and the fixed gear 62 are arranged in the input region R1. The second tooth T2 of the planetary gear 65 and the output gear 66 are arranged in the output region R2.

In the input region R1, input rotation from the motor excitation device 2 (as an electric motor) is input to the sun gear 56, which meshes with the first tooth T1 of the planetary gear 65. In the output region R2, output rotation is output to the output shaft 70 from the output gear 66, which meshes with the second tooth T2 of the planetary gear 65.

(fixed gear)
The fixed gear 62 is in a ring shape, for example, made by molding resin. For example, a flange (not shown) may be formed on the outer periphery of the fixed gear 62, and recesses (not shown) and protrusions (not shown) for fixing the fixed gear 62 to the upper part of the gear case 61 may be formed alternately in the circumferential direction. As shown in FIG. 2 , a ring gear 62A is formed on the inner periphery of the fixed gear 62.

The fixed gear 62 has a different number of teeth than the output gear 66. In this embodiment, the root diameter of the fixed gear 62 is, for example, 15 mm or less. However, in this disclosure, the root diameter of the fixed gear 62 is not limited to this and can be set arbitrarily.

(Sun Gear)
As shown in Fig. 2, the sun gear 56 is disposed concentrically with the fixed gear 62. Input rotation is input to the sun gear 56. The sun gear 56 meshes only with the first tooth T1 of the planetary gear 65. For ease of viewing, the carrier 64 illustrated in Fig. 1 is omitted from Fig. 2.

(Career)
The carrier 64 is formed, for example, by molding plastic, and includes a pair of disks, each having a hole in the center through which the shaft 42 passes. Three masts and three partitions extending upward are arranged alternately in the circumferential direction around the periphery of the upper surface of the disks. The carrier 64 constitutes the reduction mechanism 60. Three planetary gears 65 are rotatably supported by the carrier 64. The holes, masts, and partitions of the carrier 64 are omitted from the illustration for clarity.

(output gear)
As shown in Fig. 2, the output gear 66 is a cylindrical member with a bottom, having a bottom 66A and a wall 66B rising from the periphery of the bottom 66A. A hole 66C is formed in the center of the bottom 66A, into which the cylindrical portion 70C of the output shaft 70 is press-fitted. An output-side internal gear 66D is formed on the inner periphery of the output gear 66, thereby forming a ring gear. The output gear 66 is provided in the output region R2 and meshes with the second teeth T2.

(storage space)
4, a storage space S capable of storing a fluid is formed inside the output gear 66, which is a cylindrical member with a bottom. The fluid may be, for example, a refrigerant that moves from the valve body 76 to the output gear 66 as the motor-operated valve 1 is used, or grease, lubricating oil, or refrigeration oil used in the reduction mechanism 60. In particular, the space inside the second tooth T2, where the sun gear 56 is not present, is a space where no other gears are present even when the planetary gear reduction mechanism is driven, and is therefore suitable for storing grease or lubricating oil.

In this embodiment, the bottom 66A and wall 66B do not have any openings such as holes, which prevents fluid from leaking out of the storage space S. By positioning the bottomed output gear 66 at the lowest stage in the reduction mechanism 60, fluid such as a lubricating fluid can be accumulated in the inner storage space S.

(planetary gear)
The planetary gear 65 has a plurality of first teeth T1 arranged to be located in the input region R1, and a plurality of second teeth T2 arranged to be located in the output region R2 corresponding to each of the plurality of first teeth T1.

As shown in FIG. 3, each of the multiple first teeth T1 is bilaterally symmetrical about a first center line A1 in a plan view. The first center line A1 is an imaginary line that extends radially through the central axis V of rotation of the planetary gear 65 and the circumferential center of the first pitch circle C1 of the first tooth T1.

As shown in FIG. 4, each of the multiple second teeth T2 is symmetrical about the second center line A2 in a plan view. The second center line A2 is an imaginary line that extends radially through the central axis V of rotation of the planetary gear 65 and the circumferential center of the second tooth T2 on the second pitch circle C2. Also shown in FIG. 4 is an example of the groove width GT between adjacent teeth in the circumferential direction on the pitch circle CT of the output-side internal gear 66D of the output gear 66.

As shown in Figure 5, the planetary gear 65 is a cylindrical member. A hole 65H is formed in the center of the planetary gear 65, which rotatably fits onto the mast of the carrier 64. A first tooth T1 and a second tooth T2 are provided on the outer periphery of the planetary gear 65 as a gear portion. Although not shown, a washer-like plate having a hole in the plate, similar to the plate on the lower surface, is placed on the upper surface of the carrier 64, onto which the planetary gear 65 is fitted onto each mast. Furthermore, the protrusions on the tops of the mast and bulkhead are press-fitted into the hole in the plate, thereby rotatably fixing the planetary gear 65 to the carrier 64.

In this embodiment, the first tooth T1 and the second tooth T2 are integrally formed within the single planetary gear 65 using the same material, for example, metal. Note that in the present disclosure, the first tooth T1 and the second tooth T2 may also be fabricated separately and then integrated with each other to form a single planetary gear.

As shown in Figures 5 and 6, the second tooth T2 has a module that is different from the module of the first tooth T1. In other words, one planetary gear 65 has a portion where teeth with different modules are arranged in two rows in the vertical direction in Figure 6.

As shown in FIG. 7, in the planetary gear 65 of this embodiment, the corresponding first center line A1 and second center line A2 overlap in a plan view. That is, the corresponding first center line A1 and second center line A2 are arranged parallel to each other in the same plane that includes the central axis V of the planetary gear 65, which is aligned in the vertical direction in FIG. 6. Furthermore, the number of teeth of the second teeth T2 is the same as the number of teeth of the first teeth T1.

However, as shown in Figure 7, the diameter of the second pitch circle C2 of the second tooth T2 is smaller than the diameter of the first pitch circle C1 of the first tooth T1. Therefore, the module of the second tooth T2 is smaller than the module of the first tooth T1. Furthermore, the total tooth height H2 of the second tooth T2 is lower than the total tooth height H1 of the first tooth T1. Furthermore, the second groove width G2 of the second tooth T2 is narrower than the first groove width G1 of the first tooth T1. The groove width is the length measured circumferentially of the groove formed between adjacent teeth in the circumferential direction.

In this embodiment, the example is given of making the modules of the first tooth T1 and the second tooth T2 different from each other by changing only the diameter of the pitch circle, but this disclosure is not limited to this. In this disclosure, the modules of the first tooth T1 and the second tooth T2 may be made different from each other by changing only the number of teeth, or by changing both the number of teeth and the diameter of the pitch circle.

(Method of assembling the motor-operated valve)
Next, a method for assembling the motor-operated valve according to this embodiment will be described. First, the fixed gear 62, the output gear 66, and the planetary gear 65 are assembled to form the planetary gear type reduction mechanism 60.

Specifically, the assembler places the valve body 10 in a fixed state on, for example, an assembly workbench. Inside the valve body 10, the components located below the reduction gear mechanism 60, such as the output shaft 70, threaded shaft 71, holder 72, bearing 73, ball 74, ball receiving member 74A, valve stem 75, and valve body 76, are assembled. Furthermore, the protrusion 71A of the threaded shaft 71 is engaged with the second hole 70B of the output shaft 70, and the end of the shaft 42 on the output shaft 70 side is not inserted into the first hole 70A of the output shaft 70.

Next, the assembler positions the output gear 66 so that the bottom 66A is facing downwards. The assembler also positions the hole 66C of the output gear 66 concentrically with the first hole 70A of the output shaft 70. Next, the assembler places the fixed gear 62 concentrically on top of the output gear 66.

Next, the assembler inserts the planetary gear 65 supported by the carrier 64 from the top of the fixed gear 62, with the second teeth T2 (lower side in Figure 5) at the leading edge. As shown in Figure 5, the planetary gear 65 has first teeth T1 on the upper side and second teeth T2 on the lower side corresponding to the first teeth T1. The second teeth T2 have the same number of teeth as the first teeth T1, and the diameter of the second pitch circle C2 of the second teeth T2 is smaller than the diameter of the first pitch circle C1 of the first teeth T1.

The assembler then meshes the first tooth T1 with the ring gear 62A of the fixed gear 62 and the second tooth T2 with the output-side internal gear 66D of the output gear 66. In other words, by inserting the planetary gear 65 into the space inside the integrally arranged fixed gear 62 and output gear 66, the planetary gear 65, fixed gear 62, and output gear 66 are meshed continuously over time.

In this embodiment, the process of inserting the planetary gear 65 into the space inside the fixed gear 62 and the output gear 66 is performed after the process of integrating the output gear 66 and the fixed gear 62. However, in this disclosure, the order of the assembly processes is not limited to this. In this disclosure, the order of the assembly processes can be changed as appropriate, for example, so that after the process of inserting the second tooth of the planetary gear 65 into the output gear 66, the process of inserting the fixed gear 62 into the first tooth of the planetary gear 65 protruding from the output gear 66 is performed.

The assembler then inserts the sun gear member 54 from above the fixed gear 62 so that the sun gear 56 meshes with the three planetary gears 65 inside the carrier 64. Through the above series of steps, the planetary gear reduction mechanism 60 of this embodiment can be fabricated. The assembler then attaches other components, such as the shaft 42 and can 30, from above to the fabricated planetary gear reduction mechanism 60, thereby assembling the motor-operated valve 1 of this embodiment.

(Action and effect)
In the motor-operated valve 1 according to this embodiment, the module of the first tooth T1 is different from the module of the second tooth T2. This allows the planetary gear reduction mechanism to be designed without being restricted by the requirement that the module of the first tooth and the module of the second tooth be the same, thereby improving the design freedom of the planetary gear reduction mechanism. Similarly, this also improves the design freedom of the motor-operated valve 1 according to this embodiment.

Furthermore, this embodiment realizes a paradox planetary gear reduction mechanism, particularly a planetary gear reduction mechanism equipped with a fixed gear 62 and a sun gear 56, among other planetary gear reduction mechanisms.

Furthermore, this embodiment particularly improves the design freedom of a small motor-operated valve 1 in which the root diameter of the fixed gear 62 is 15 mm or less.

Furthermore, this embodiment particularly improves the design freedom of motor-operated valves 1 in which a rotor assembly and a planetary gear reduction mechanism are disposed in the space between the valve body and the can.

In addition, in this embodiment, a storage space S capable of accumulating fluid is formed inside the cylindrical member. Here, for example, by configuring the number of teeth of the second teeth T2 of the planetary gear 65 to be the same as the number of teeth of the first teeth, and making the diameter of the second pitch circle C2 of the second teeth T2 smaller than the diameter of the first pitch circle C1 of the first teeth T1, the module of the second teeth T2 can be made smaller than the module of the first teeth T1, thereby reducing the number of teeth of the output gear 66 that mesh with the second teeth T2.

The volume of the storage space S increases as the diameter of the second tooth T2 decreases. For example, if the fluid stored in the storage space S is a lubricating fluid, the volume of lubricating fluid that can be held in the storage space S increases, improving the lubrication of the motor-operated valve 1.

Furthermore, when assembling a relatively small planetary gear reduction mechanism, for example, multiple planetary gears are often integrated by rotatably supporting them on a single carrier. Because the planetary gears are rotatable, when inserting the planetary gears into the output gear or fixed gear, it is difficult for the tooth closest to the internal tooth of the output gear or fixed gear to mesh with the internal tooth of the output gear or fixed gear. In other words, the teeth of the multiple planetary gears and the internal tooth of the output gear or fixed gear do not mesh with each other if the teeth and grooves are in their current positional relationship.

For this reason, when inserting the gears, it is necessary to slightly rotate some or all of the planetary gears while they are supported by the carrier, thereby changing the relative positions of the planetary gear teeth so that they mesh with the internal teeth of the output gear or fixed gear.

In particular, when the numbers of first and second teeth provided in two rows, upper and lower, on a planetary gear are different, the first teeth and second teeth do not correspond one-to-one. In other words, there will be many teeth with different relative positional relationships between the first and second teeth, such that the directions of the first center lines of the first teeth and the second center lines of the second teeth are randomly arranged. In particular, when the numbers of meshing teeth are prime, the relative positional relationships of all teeth will be different between the first and second teeth.

For this reason, if the number of teeth differs between the first and second teeth of the planetary gear, the labor required to change the relative positions of the planetary gear teeth when inserting the planetary gear into the output gear or fixed gear while the planetary gear is supported by the carrier is significant.

In contrast, in this embodiment, even if the modules of the first tooth T1 and the second tooth T2 are different, the number of teeth of the first tooth T1 and the number of teeth of the second tooth T2 are the same. Therefore, when the planetary gear 65 is supported by the carrier 64 and inserted into the output gear 66 or the fixed gear 62, the burden of changing the positional relationship of the teeth of the planetary gear 65 can be reduced compared to when the number of teeth of the first tooth T1 and the second tooth T2 are different.

In addition, in this embodiment, the number of teeth of the output gear 66 that mesh with the second tooth T2 can be reduced, so the gap between adjacent teeth on the output gear 66 is wider than when the number of teeth on the output gear 66 is the same. This makes it easier to insert the planetary gear 65 into the output gear 66 and the fixed gear 62.

In particular, the smaller the motor-operated valve, the smaller the gaps between adjacent teeth on the output gear 66 tend to be, making it more difficult to insert the planetary gear 65 into the output gear 66 and the fixed gear 62 during assembly. One possible way to improve ease of insertion of the planetary gear 65 is to narrow the lower ends of the teeth so that the overall tooth height decreases as the shape of the lower part of the planetary gear 65 decreases downward, but this reduces the volume of the teeth, which is likely to result in a decrease in strength, and therefore a decrease in the durability of the motor-operated valve. The present embodiment is advantageous in that it improves ease of insertion of the planetary gear 65 without the need to reduce the volume of the teeth.
<Other embodiments>

The present disclosure has been described using the disclosed embodiments above, but the descriptions and drawings that form part of this disclosure should not be understood to limit the present disclosure. The present disclosure includes various embodiments not described above, and the technical scope of the present disclosure is defined only by the inventive features of the claims that are appropriate from the above description.

1 Electric valve 2 Motor excitation device (electric motor)
3 Coil 4 Electric circuit 5 Mounting fixture 10 Valve body 12 Valve chamber 14 Orifice 17 Valve seats 18A, 18B Piping 20 Receiving member 24 Compression coil spring 26 Spring receiving member 26A Small diameter portion 26B Large diameter portion 26C Flange-shaped portion 26D Step portion 30 Can 40 Bearing 41 Hole 42 Shaft 50 Rotor assembly 54 Sun gear member 56 Sun gear 58 Through hole 60 Planetary gear type reduction mechanism 61 Gear case 62 Fixed gear 62A Ring gear 64 Carrier 65 Planetary gear 65H Hole 66 Output gear 66A Bottom portion 66B Wall portion 66C Hole 66D Output side internal gear 70 Output shaft 70A First hole 70B Second hole 70C Cylindrical portion 71 Screw shaft 71A Protrusion portion 71B Recessed portion 72 Holder 73 Bearing 74 Ball 74A Ball receiving member 75 Valve stem 75A Spring receiving portion 76 Valve body A1 First center line A2 Second center line C1 First pitch circle C2 Second pitch circle CT Pitch circle G1 of output side internal gear First groove width G2 Second groove width GT Groove width H1 of output side internal gear First tooth depth H2 Second tooth depth R1 Input area R2 Output area S Storage space T1 First tooth T2 Second tooth V Central axis X of planetary gear Central axis

Claims (6)

An electric motor;
a planetary gear type reduction mechanism including: a planetary gear including first teeth to which an input rotation of the electric motor is input; and second teeth provided corresponding to the first teeth and having a module different from that of the first teeth and the same number of teeth as that of the first teeth; an output gear that meshes with the second teeth and outputs an output rotation that is reduced from the input rotation ; and a fixed gear that meshes with the first teeth and has a number of teeth different from that of the output gear .
a valve body that controls the opening degree of the valve by the output rotation;
An electric valve comprising: The planetary gear reduction mechanism includes:
a sun gear that is concentrically disposed with the fixed gear and receives the input rotation and meshes with the first tooth of the planetary gear ;
Equipped with
The motor-operated valve according to claim 1 . The tooth root diameter of the fixed gear is 15 mm or less.
The motor-operated valve according to claim 2. a valve body having a valve chamber formed therein;
a valve seat having an opening formed in a part of a wall surface of the valve chamber;
a valve body arranged to be able to open and close the opening of the valve seat;
a valve stem that moves the valve element toward and away from the valve seat;
a cylindrical can attached to the valve body and forming a space between the can and the valve body;
an excitation device for the electric motor attached to the outer periphery of the can;
a permanent magnet rotor assembly rotatably supported inside the can and rotated by the excitation device;
a screw mechanism that converts the output rotation from the planetary gear reduction mechanism into a movement of the valve disc toward or away from the valve seat and transmits the movement to the valve stem;
the rotor assembly and the planetary gear type reduction mechanism are disposed in the space between the valve body and the can.
The motor-operated valve according to any one of claims 1 to 3. the output gear is a cylindrical member having a bottom and a wall rising from a peripheral edge of the bottom,
A storage space capable of storing a fluid is formed inside the cylindrical member.
The motor-operated valve according to claim 4. a planetary gear including a first tooth to which an input rotation from an external source is input, and a second tooth provided corresponding to the first tooth and having a module different from that of the first tooth and the same number of teeth as that of the first tooth; an output gear that meshes with the second tooth and outputs an output rotation that is a reduced version of the input rotation; and a fixed gear that meshes with the first tooth and has a number of teeth different from that of the output gear.
A planetary gear type reduction mechanism having the above structure.