Motorized valve

Abstract

Provided is a motorized valve which is relatively inexpensive and is stably usable for a long time.　The motorized valve comprises a valve main body which is provided with a valve seat, a valve chamber, and an orifice passage, a valve shaft which is rotationally driven by a motor and is displaced in the axial direction, a valve holder which is held by the valve shaft, a first valve body which is fixed to the valve holder and is provided with a through hole, a second valve body which is disposed between the valve shaft and the first valve body, an elastic body which biases the second valve body in a direction away from the first valve body, and a seal holder which is provided with a holder base that is disposed inside the valve main body, wherein sealing is performed between the outer periphery of the holder base and the inner periphery of the valve main body, an annular sealing body is disposed between the inner periphery of the holder base and the outer periphery of the valve holder, the orifice passage and the inner space of the valve main body can communicate with each other via the through hole in a state where the first valve body is seated on the valve seat inside the valve chamber, and the through hole is closed when the second valve body abuts on the first valve body.

Description

Motor-operated valve

[0001] The present invention relates to a motor-operated valve.

[0002] A motor-driven electric valve has a screw mechanism in which the male thread of a valve stem, driven by a stepping motor, is threaded into a female threaded hole in the valve body. This screw mechanism rotates the valve stem around its axis and displaces it axially, increasing or decreasing the gap between the valve disc and the valve seat, thereby controlling the flow rate.

[0003] For example, Patent Document 1 discloses an electrically operated valve having a valve seat with a relatively large inner diameter to ensure a sufficient flow rate when the valve is open. In such an electrically operated valve, when the valve is closed, it is necessary to prevent fluid leakage from the valve chamber to the low-pressure piping at two locations: between the valve disc seated on the valve seat and the valve seat, and between the O-ring that seals between the valve disc and a base member fixed to the valve body.

[0004] Japanese Patent Application Laid-Open No. 2019-65898

[0005] To improve the sealing performance between the base member and the valve body, it is necessary to increase the tension of the O-ring, but this poses problems such as reduced sliding properties and increased motor load. Also, assuming long-term use, it is desirable to select an O-ring made of a material that is less susceptible to deterioration due to heat, but this also presents the problem of limiting the freedom of material selection.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a motor-operated valve that is relatively inexpensive and can be used stably for a long period of time.

[0007] the valve body is provided with a seal holder having a holder base disposed within the valve body, wherein the outer periphery of the holder base and the inner periphery of the valve body are sealed, and an annular seal body is disposed between the inner periphery of the holder base and the outer periphery of the valve holder, and when the first valve body is seated on the valve seat within the valve chamber, the orifice path and the internal space of the valve body can communicate via the through hole, and when the second valve body abuts against the first valve body, the through hole is closed.

[0008] According to the present invention, it is possible to provide a motor-operated valve that is relatively inexpensive and can be used stably for a long period of time.

[0009] Fig. 1 is a longitudinal cross-sectional view of a motor-operated valve according to an embodiment of the present invention, showing the valve in a closed state. Fig. 2 is a longitudinal cross-sectional view of a motor-operated valve according to an embodiment of the present invention, showing the valve in a partially open state. Fig. 3 is a longitudinal cross-sectional view of a motor-operated valve according to an embodiment of the present invention, showing the valve in a fully open state. Fig. 4 is an enlarged view of the vicinity of the valve chamber of the motor-operated valve shown in Fig. 3.

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] Figures 1 to 3 are longitudinal cross-sectional views showing a motor-operated valve 1 according to an embodiment of the present invention. Figure 4 is an enlarged view showing the vicinity of the valve chamber of the motor-operated valve 1 shown in Figure 3. Here, "upper" refers to the rotor side relative to the valve seat, and "lower" refers to the valve seat side relative to the rotor.

[0012] (Configuration of Motor-Operated Valve) The motor-operated valve 1 comprises a cylindrical valve body 10 with a bottom and an open top, a cylindrical can 45 with a top whose lower end is hermetically joined by welding or the like to the upper end surface of the valve body 10, a guide stem 15 fixed to the inside of the valve body 10, a valve shaft 21 disposed inside the guide stem 15, a rotor 30 connected and fixed to the valve shaft 21 so as to be integrally rotatable, and a stator 50 fitted onto the outer periphery of the can 45. The axis of the motor-operated valve 1 is designated as L.

[0013] The valve body 10 comprises a hollow cylindrical portion 10a and a bottom wall portion 10b, which are connected together. The thicknesses of the hollow cylindrical portion 10a and the bottom wall portion 10b are substantially equal. The interior of the hollow cylindrical portion 10a defines a valve chamber VC.

[0014] A circular opening 10d is formed in the center of the bottom wall portion 10b, and a valve seat member 11 is fixed to the opening 10d by brazing or the like. Here, the valve seat member 11 is considered to constitute a part of the valve body 10.

[0015] The valve seat member 11 comprises a hollow reduced-diameter cylindrical portion 11a and a hollow expanded-diameter cylindrical portion 11b, which are connected together in the direction of the axis L. The reduced-diameter cylindrical portion 11a is fitted into the opening 10d and brazed. The end of the first pipe T1 is fitted into the inner periphery of the expanded-diameter cylindrical portion 11b and connected thereto by brazing or the like.

[0016] 4, the valve seat member 11 has a cylindrical upper opening 11c from the upper end side, a tapered middle opening 11f whose diameter decreases as it extends downward, and a cylindrical orifice passage 11d whose diameter is smaller than that of the upper opening 11c. The first pipe T1 is positioned so as to abut against a step immediately below the orifice passage 11d, and its inner diameter is larger than that of the orifice passage 11d. A tapered valve seat 11e whose diameter increases as it extends upward is formed on the inner periphery of the upper end of the upper opening 11c.

[0017] 1 to 3, an inlet opening 10e is formed in the hollow cylindrical portion 10a of the valve body 10, and the end of the second pipe T2 is inserted into the inlet opening 10e and connected by brazing or the like. The axis of the inlet opening 10e is designated as O. The axis O is perpendicular to the axis L.

[0018] The lower end of the can 45 abuts against the upper end of the valve body 10, and the valve body 10 and the can 45 are joined by welding to form a sealed integrated body. A flange-shaped disk 18 is disposed inside the lower end of the can 45 at the upper end of the valve body 10. It is preferable that the flange-shaped disk 18 be welded over its entire circumference at the same time that the valve body 10 and the can 45 are welded together.

[0019] A yoke 51, a bobbin 52, and a stator coil 53 are arranged outside the can 45 to form the stator 50, the outer periphery of which is covered by a resin molded cover 58. In this embodiment, the resin molded cover 58 covers the entire stator 50, including the upper part of the can 45, but it may also cover only the periphery of the yoke 51. The rotor 30 and the stator 50 constitute a stepping motor.

[0020] The stator coil 53 is connected to an external power supply circuit (not shown) via a substrate CB, a connector CN, and wiring HN. The substrate CB and the connector CN are covered by another resin cover 57. When the stator coil 53 is energized and excited, the rotor 30 disposed within the can 45 can rotate about the axis L. The interior of the resin cover 57 is filled with a mold resin MR.

[0021] The guide stem 15, disposed inside the rotor 30, comprises a solid cylindrical main body 15a and a hollow cylindrical portion 15b connected together. A female threaded hole (female threaded portion) 15c is formed in the main body 15a, penetrating its center in the direction of the axis L. A flanged disk 18 is fixed to the outer circumferential groove of the expanded diameter portion 15e on the lower end of the hollow cylindrical portion 15b. As described above, the flanged disk 18 is welded to the upper end of the valve body 10, thereby fixing the guide stem 15 to the valve body 10. A pressure equalizing hole 15d is formed in the hollow cylindrical portion 15b, penetrating from the inner to the outer periphery.

[0022] Furthermore, in order to set the control origin position of the rotor 30 and the valve shaft 21, a valve closing direction fixed stopper 55 having a rectangular cross section is provided to protrude upward from the upper surface of the main body 15a of the guide stem 15, and a valve opening direction fixed stopper 56 having a rectangular cross section is provided to protrude downward from the lower surface of the main body 15a of the guide stem 15. Here, the control origin position of the rotor 30 and the valve shaft 21 refers to the position when the valve closing direction movable stopper 35 abuts against and is locked against the valve closing direction fixed stopper 55, and the rotor 30 and the valve shaft 21 reach their lowest positions.

[0023] The valve stem 21 comprises a small-diameter portion 21a fitted with an annular connector 32 attached to the rotor 30, a male threaded portion 21b that screws into the female threaded hole 15c of the guide stem 15, a valve stem cylindrical portion 21c formed below the male threaded portion 21b, an outer flange portion 21d that extends radially outward from the lower end of the valve stem cylindrical portion 21c, and a small cylindrical portion 21e that protrudes downward from the lower end of the valve stem cylindrical portion 21c. The outer diameter of the small cylindrical portion 21e is smaller than that of the valve stem cylindrical portion 21c.

[0024] A valve closing direction movable stopper 35 is threadedly engaged with the upper end of the male threaded portion 21b of the valve shaft 21 and is engaged with the lower surface of the upper wall of the rotor 30. A stopper portion 35a having a rectangular cross section is formed on the lower surface of the valve closing direction movable stopper 35.

[0025] A valve opening direction movable stopper 36 is threadedly engaged with the lower end of the male threaded portion 21b of the valve shaft 21 and is engaged with the upper surface of the valve holder 23. A stopper portion 36a having a rectangular cross section is formed on the upper surface of the valve opening direction movable stopper 36.

[0026] In Figure 4, a valve holder 23 is attached to the lower end of the valve stem 21. The valve holder 23 is composed of an outer wall portion 23a and an inner flange portion 23b that extends radially inward from the upper end of the outer wall portion 23a. The outer wall portion 23a has an inner periphery with a larger diameter than the outer flange portion 21d, while the inner flange portion 23b has an inner periphery with a smaller diameter than the outer flange portion 21d. A circular opening 23c is formed in the center of the inner flange portion 23b, and this circular opening 23c slidably fits onto the valve stem cylindrical portion 21c. The outer periphery of the outer wall portion 23a slidably fits onto the inner periphery of the hollow cylindrical portion 15b of the guide stem 15. Furthermore, a plurality of communication holes 23d are formed near the upper end of the outer wall portion 23a, arranged circumferentially and penetrating radially.

[0027] The lower end of the outer wall portion 23a is connected to a first valve body (also simply referred to as a valve body) 24. The first valve body 24 comprises an upper cylindrical portion 24a, which is fitted to the outer wall portion 23a and fixed by press-fitting or welding, and a lower cylindrical portion 24b, which are connected together. A tapered portion 24c, which decreases in diameter as it extends downward, is formed at the lower end of the lower cylindrical portion 24b. The first valve body 24 also has a through-hole 24d that penetrates vertically along the axis L. The through-hole 24d connects a space on the valve stem side (an intermediate chamber MC above the first valve body 24) with a space on the opposite side (a space below the first valve body 24 that connects to the orifice passage 11d) via a seal holder 29, which will be described later.

[0028] A second valve body 25 is disposed inside the valve holder 23. The second valve body 25 is made of metal (e.g., SUS) and has a substantially cylindrical valve body base 25a, a valve body flange 25b extending radially outward from the upper end of the valve body base 25a, and a hemispherical portion 25c with a spherical surface formed at the lower end of the valve body base 25a.

[0029] The coil spring (elastic body) 26 has its upper end abutting against the lower end of the valve body flange portion 25b and its lower end abutting against the upper surface of the first valve body 24, and urges the second valve body 25 in a direction away from the first valve body 24.

[0030] An annular thrust bearing 27 is disposed between the second valve body 25 and the valve shaft 21. The thrust bearing 27 is disposed around the small cylindrical portion 21e of the valve shaft 21 and abuts against the upper surface of the second valve body 25 and the lower surface of the outer flange portion 21d, allowing the second valve body 25 and the valve shaft 21 to rotate relative to each other with low friction.

[0031] In addition, a washer 28, which is an annular plate, is disposed between the outer flange portion 21d of the valve shaft 21 and the inner flange portion 23b of the valve holder 23. The washer 28 also enables the outer flange portion 21d and the inner flange portion 23b to rotate relative to each other with low friction.

[0032] A seal holder 29 is disposed between the valve holder 23 and the hollow cylindrical portion 10a of the valve body 10. The seal holder 29 comprises an annular holder base 29a, an annular holder flange 29b extending radially outward from the upper end of the holder base 29a, and a circular bottom wall 29c extending radially outward from the lower end of the holder base 29a (connected via a small cylindrical portion). An annular recess 29e is coaxially formed at the upper end of the holder base 29a (radially inward of the holder flange 29b). An outer wall 23a of the valve holder 23 slidably fits into a holder opening 29d penetrating the bottom wall 29c, and the outer wall 23a protrudes downward from the valve holder 23.

[0033] The holder flange portion 29b is sandwiched and placed between the upper end of the hollow cylindrical portion 10a and the lower surface of the flange-shaped disk 18, with a gap radially inward from the inner periphery of the end of the can 45, and is welded as described below. The outer periphery of the expanded diameter portion 15e on the lower end of the guide stem 15 is disposed opposite the inner periphery of the holder flange portion 29b. The tip of the second pipe T2 is disposed in contact with the outer periphery of the bottom wall portion 29c, thereby enabling the insertion position of the second pipe T2 to be determined.

[0034] An O-ring OR and a sliding member SD are disposed on the inner periphery of the holder base 29a, which is sandwiched between the lower end of the guide stem 15 and the bottom wall 29c. The O-ring OR and the sliding member SD form an annular seal. The sliding member SD is a flexible cylindrical body made of a low-friction material such as PTFE, which has a lower friction coefficient than the O-ring OR, and is disposed between the O-ring OR and the outer wall 23a. Therefore, while the holder base 29a and the outer wall 23a can be displaced relative to each other in the direction of the axis L, the O-ring OR and the sliding member SD can seal the fluid. It is also possible to dispose only the O-ring OR without providing the sliding member SD.

[0035] The internal space of the motor-operated valve 1 (the space surrounded by the can 45 and the valve body 10) is divided into a high-pressure valve chamber VC, an intermediate chamber MC in the valve holder 23, and a back pressure chamber BC in the can 45. An O-ring OR and a sliding member SD seal between the valve chamber VC and the intermediate chamber MC.

[0036] Here, when the gap between the outer periphery of the lower end expanded diameter portion (cylindrical fitting portion) 15e and the inner periphery of the annular recess (cylindrical fitted portion) 29e is defined as A, and the gap between the outer periphery of the holder base 29a and the inner periphery of the hollow cylindrical portion 10a of the valve body 10 is defined as B, then B > A holds.

[0037] 1 to 3 , in this embodiment, the rotor 30, valve stem 21, valve opening direction movable stopper 36, valve holder 23, washer 28, thrust bearing 27, second valve body 25, coil spring 26, and first valve body 24 are displaceable in the direction of axis L relative to the guide stem 15 and seal holder 29 fixed to the valve body 10. Furthermore, the valve holder 23 and first valve body 24 are displaceable in the direction of axis L relative to the valve stem 21. Furthermore, the second valve body 25 is displaceable in the direction of axis L relative to the valve stem 21 and first valve body 24.

[0038] (Assembly Process of Motor-Operated Valve) The assembly process of the motor-operated valve 1 will be described. First, the guide stem 15, to which the flanged disk 18 is attached, is joined to the seal holder 29, to which the O-ring OR and sliding member SD are attached, to create a first assembly. The seal holder 29 may be welded to the flanged disk 18 at this point, or may be welded simultaneously when the flanged disk 18 is welded to the valve body 10. This creates a seal between the seal holder 29 and the valve body 10 (i.e., between the outer periphery of the holder base 29a and the inner periphery of the valve body 10).

[0039] Furthermore, after assembling the washer 28 and the valve holder 23 from the male thread portion 21b side of the valve shaft 21, the valve opening direction movable stopper 36 is screwed onto the male thread portion 21b and assembled. After that, the thrust bearing 27, the second valve body 25, and the coil spring 26 are placed inside the valve holder 23, and the first valve body 24 is welded to the lower end of the valve holder 23 to produce a second assembly.

[0040] The male threaded portion 21b of the second assembly formed in this manner is screwed into the female threaded hole 15c of the first assembly, and the movable stopper 35 for the valve closing direction is screwed into the male threaded portion 21b protruding from the guide stem 15, and then the rotor 30 is assembled to produce the third assembly.

[0041] Furthermore, the valve seat member 11 is brazed to the valve body 10, and the valve stem 21 of the third assembly and the valve seat member 11 are coaxially positioned using a jig or the like, while the third assembly is housed in the can 45, and the valve body 10, can 45, and flanged disk 18 are fixed by welding. Thereafter, the pipes T1 and T2 are brazed, and the stator 50 is attached to the can 45, thereby completing the motor-operated valve 1.

[0042] 4, according to this embodiment, a gap A (preferably an interference fit) between the outer periphery of the lower-end expanded diameter portion 15e and the inner periphery of the annular recess 29e is smaller than a gap B between the outer periphery of the valve holder 23 and the inner periphery of the hollow cylindrical portion 10a of the valve body 10. This gap B can be used to adjust the valve holder 23 and the first valve body 24 together with the seal holder 29 in a direction perpendicular to the axis, thereby centering the valve stem 21 and the valve seat member 11. Since the coaxiality of the guide stem 15 and the seal holder 29 is ensured by the precision of machining, by installing the seal holder 29 coaxially with the axis L of the valve body 10 (valve seat member 11), the coaxiality of the valve seat 11e and the first valve body 24 can be easily ensured, thereby suppressing fluid leakage.

[0043] (Operation of the Motor-Operated Valve) Next, the operation of the motor-operated valve 1 will be described in detail. First, it is assumed that a fluid (refrigerant) is flowing into the valve chamber VC from the second pipe T2, and the motor-operated valve 1 is in the closed state shown in FIG. 1 . At this time, the lower end of the lowered valve stem 21 presses against the upper end of the second valve body 25, causing the second valve body 25 to descend against the biasing force of the coil spring 26, and the hemispherical portion 25c maintains a state in which it closes the upper end of the through-hole 24d. Even if the second valve body 25 is tilted, the hemispherical portion 25c can still properly close the upper end of the through-hole 24d.

[0044] Furthermore, the upper end of the first valve body 24 is pressed by the second valve body 25, so that the semispherical portion 25c is seated on the valve seat 11e.

[0045] In the valve closed state, the tapered portion 24c is seated on the valve seat 11e, thereby preventing fluid from flowing out from the valve chamber VC into the first pipe T1. Even if fluid moves from the valve chamber VC to the intermediate chamber MC and the pressure in the intermediate chamber MC increases, the hemispherical portion 25c closes the upper end of the through hole 24d, thereby preventing fluid from flowing out from the intermediate chamber MC into the first pipe T1. In this state, the pressure of the valve chamber VC acts above the first valve body 24, and the pressure of the first pipe T1 acts below the first valve body 24, so that the first valve body 24 is stably seated on the valve seat 11e.

[0046] When pulsed power is supplied to the stator 50 from an external power supply circuit in this closed valve state, the rotor 30 and the valve shaft 21 are driven to rotate in one direction, and accordingly, the valve shaft 21 and the valve holder 23 are raised while rotating via the screw feed mechanism consisting of the female threaded hole 15c and the male threaded portion 21b.

[0047] As the valve stem 21 rises, the pressing force urging the second valve body 25 downward disappears, and as shown in Fig. 2, the second valve body 25 moves away from the first valve body 24 due to the urging force of the coil spring 26. Then, the fluid in the intermediate chamber MC flows through the through hole 24d and the orifice passage 11d to the first pipe T1 side, and the pressure in the intermediate chamber MC decreases to approach the pressure in the first pipe T1. As a result, the pressures above and below the valve seat 11e are balanced (the pressure difference between the above and below is canceled), making it easier for the first valve body 24 to rise.

[0048] As the valve stem 21 rises, the outer flange 21d also rises, urging the inner flange 23b upward via the washer 28. This causes the valve holder 23 to rise in a lifted manner, separating the first valve body 24 from the valve seat 11e and achieving the fully open valve state shown in Figure 3. At this time, the valve holder 23 rises while sliding against the sliding member SD, which is urged radially inward by the elastic force of the O-ring OR, ensuring wear resistance and sealing performance over a long period of time. Furthermore, the washer 28 slides against the outer flange 21d and the inner flange 23b as they rotate relative to each other, ensuring a low-friction state.

[0049] When the valve shaft 21 rises to a predetermined position, the movable stopper 36 for the valve opening direction abuts and engages with the fixed stopper 56 for the valve opening direction, thereby forcibly stopping the rotation and rise of the rotor 30, valve shaft 21, and valve holder 23.

[0050] When the first valve body 24 moves away from the valve seat 11e, the fluid that has flowed into the valve chamber VC from the second pipe T2 flows out to the first pipe T1 via the valve seat 11e and the orifice passage 11d. The flow rate of the outflowing fluid is determined by the gap between the tapered portion 24c and the valve seat 11e.

[0051] At this time, the intermediate chamber MC communicates with the valve chamber VC via the through-hole 24d, so the pressure in the intermediate chamber MC is approximately equal to the pressure in the valve chamber VC. In addition, the intermediate chamber MC is also communicated with the back pressure chamber BC via the communication hole 23d of the valve holder 23 and the pressure equalizing hole 15d of the guide stem 15, so the pressure in the intermediate chamber MC and the pressure in the back pressure chamber BC are approximately equal.

[0052] On the other hand, when a pulse of reverse characteristics is supplied to the stator 50 from an external power supply circuit in this fully open state, the rotor 30 and the valve shaft 21 are driven to rotate in the other direction, and the valve shaft 21 and the valve holder 23 are lowered while rotating via the screw feed mechanism consisting of the female threaded hole 15c and the male threaded portion 21b.

[0053] As the valve stem 21 descends, the outer flange 21d also descends, causing the valve holder 23 to descend, and the first valve body 24 seats on the valve seat 11e, thereby preventing fluid from passing between the first valve body 24 and the valve seat 11e from the valve chamber VC.

[0054] Furthermore, after the first valve body 24 is seated on the valve seat 11e, the second valve body 25 is pressed downward by the lower end of the valve stem 21 and displaced against the biasing force of the coil spring 26, so that the lower end of the second valve body 25 abuts against the upper end of the first valve body 24. When the lower end of the second valve body 25 abuts against the upper end of the first valve body 24, a frictional force is generated between them, so that the rotation of the second valve body 25 is forcibly stopped, while the rotation of the valve stem 21 continues. At this time, the thrust bearing 27 slides against the valve stem 21 and the second valve body 25 as they rotate relative to each other, ensuring a low-friction state.

[0055] The second valve body 25 closes the upper end of the through hole 24d, thereby preventing the fluid from flowing out from the intermediate chamber MC toward the first pipe T1.

[0056] When the valve shaft 21 descends to a predetermined position, the movable stopper 35 for the closing direction abuts and engages with the fixed stopper 55 for the closing direction, the rotor 30 and the valve shaft 21 reach their lowest positions, and the descent of the rotor 30 and the valve shaft 21 is forcibly stopped even if pulsed power supply to the stator 50 continues.

[0057] According to this embodiment, when the valve is closed, the first valve body 24 is seated on the valve seat 11e and the second valve body 25 closes the through hole 24d of the first valve body 24, so that leakage of fluid from the valve chest VC to the orifice passage 11d can be suppressed when the valve is closed, regardless of the tension of the O-ring OR, the effects of thermal deterioration, etc. This allows the use of an O-ring OR with a relatively low tension, thereby reducing the sliding resistance of the O-ring OR, thereby reducing the motor load when the valve stem 21 is displaced and increasing the degree of freedom in selecting the O-ring OR.

[0058] If fluid leakage occurs from the O-ring OR or the sliding member SD when the valve is closed, the fluid in the valve chamber VC will move from the communication hole 23d to the intermediate chamber MC, causing the pressure in the intermediate chamber MC to become equal to the pressure in the valve chamber VC. Therefore, a differential pressure between the pressure in the through hole 24d (low pressure) and the pressure in the intermediate chamber MC (high pressure) will act on the second valve body 25. However, when the valve is opened, the second valve body 25 first opens the through hole 24d, causing the fluid in the intermediate chamber MC to move through the through hole 24d toward the orifice passage 11d in the valve seat member 11. Therefore, the fluid pressures above and below the first valve body 24 are balanced, so that the first valve body 24 subsequently opens without any problems.

[0059] In this embodiment, the O-ring OR and the sliding member SD are disposed radially outward of the valve holder 23 via the seal holder 29 fixed to the valve body 10, allowing their diameters to be relatively large. This makes it possible to suppress variations in the tension force of the O-ring OR, and also makes it less likely that damage will occur to the O-ring OR and the sliding member SD even if an excessive differential pressure is applied to them.

[0060] The present invention is not limited to the above embodiment. For example, the second valve body is configured from a cylindrical member with a hemispherical portion formed at the end, but the second valve body may also be configured by fastening a spherical body to the end of a cylindrical member. Also, the seal holder 29, O-ring OR, and sliding member SD do not necessarily have to be provided.

[0061] This specification includes the following disclosures of the invention: (First Aspect) A motor-operated valve comprising: a valve body having a valve seat, a valve chamber, and an orifice passage; a valve stem that is rotationally driven by a motor and displaces axially; a valve holder held by the valve stem; a first valve element fixed to the valve holder and having a through hole; a second valve element disposed between the valve stem and the first valve element; an elastic element that biases the second valve element in a direction separating it from the first valve element; and a seal holder having a holder base disposed within the valve body, wherein a seal is formed between an outer periphery of the holder base and an inner periphery of the valve body, and an annular seal element is disposed between the inner periphery of the holder base and the outer periphery of the valve holder, wherein when the first valve element is seated on the valve seat within the valve chamber, the orifice passage and an internal space of the valve body can communicate via the through hole, and the through hole is closed when the second valve element abuts against the first valve element.

[0062] (Second aspect) The motor-operated valve of the first aspect, characterized in that when the valve stem is displaced toward the valve seat side, the first valve body is seated on the valve seat, and then the second valve body closes the through-hole of the first valve body, and when the valve stem is displaced in the opposite direction to the valve seat side, the second valve body moves away from the first valve body, and then the first valve body moves away from the valve seat.

[0063] (Third Aspect) The motor-operated valve of the first or second aspect, characterized in that the annular seal body is composed of an O-ring arranged on the seal holder side and a sliding member arranged on the valve holder side, the sliding member having a smaller coefficient of friction than the O-ring.

[0064] (Fourth Aspect) The motor-operated valve of any one of the first to third aspects, characterized in that, when the first valve body is seated on the valve seat, the orifice passage can communicate with an intermediate chamber inside the valve holder via the through hole, and the annular seal body seals between the valve chamber and the intermediate chamber.

[0065] (Fifth Aspect) The motor-operated valve according to the fourth aspect, wherein the intermediate chamber communicates with a back pressure chamber in a can housing a rotor of the motor.

[0066] (Sixth Aspect) The motor-operated valve according to any one of the first to fifth aspects, wherein the second valve body has a spherical surface that blocks the through hole.

[0067] REFERENCE SIGNS LIST 1 Motor-operated valve 10 Valve body 11 Valve seat member 11e Valve seat 15 Guide stem 21 Valve shaft 23 Valve holder 24 First valve body 25 Second valve body 26 Coil spring 27 Thrust bearing 28 Washer 29 Seal holder 30 Rotor 35 Movable stopper for valve closing direction 36 Movable stopper for valve opening direction 50 Stator 53 Stator coil 55 Fixed stopper for valve closing direction 56 Fixed stopper for valve opening direction BC Back pressure chamber MC Intermediate chamber VC Valve chest OR O-ring SD Sliding member

Claims

1. A motor-operated valve comprising: a valve body having a valve seat, a valve chamber, and an orifice passage; a valve stem that is rotated and driven by a motor and displaced in an axial direction; a valve holder held on the valve stem; a first valve body fixed to the valve holder and having a through hole; a second valve body arranged between the valve stem and the first valve body; an elastic body that biases the second valve body in a direction separating it from the first valve body; and a seal holder having a holder base arranged within the valve body, wherein the space between the outer periphery of the holder base and the inner periphery of the valve body is sealed, and an annular seal body is arranged between the inner periphery of the holder base and the outer periphery of the valve holder, and when the first valve body is seated on the valve seat within the valve chamber, the orifice passage and an internal space of the valve body can communicate via the through hole, and when the second valve body abuts against the first valve body, the through hole is closed.

2. The motor-operated valve according to claim 1, characterized in that, when the valve stem is displaced towards the valve seat, the first valve body seats on the valve seat, and then the second valve body closes the through hole of the first valve body, and, when the valve stem is displaced in the opposite direction to the valve seat, the second valve body moves away from the first valve body, and then the first valve body moves away from the valve seat.

3. The motor-operated valve according to claim 1, characterized in that the annular seal body comprises an O-ring arranged on the seal holder side and a sliding member arranged on the valve holder side and having a smaller friction coefficient than the O-ring.

4. The motor-operated valve as described in claim 1, characterized in that, when the first valve body is seated on the valve seat, the orifice passage can communicate with an intermediate chamber inside the valve holder via the through hole, and the annular seal body seals between the valve chamber and the intermediate chamber.

5. The motor-operated valve according to claim 4, wherein the intermediate chamber communicates with a back pressure chamber in a can housing a rotor of the motor.

6. The motor-operated valve according to claim 1, characterized in that the second valve body has a spherical surface that blocks the through hole.

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