Motor valve

Abstract

To provide a motor valve which is relatively inexpensive and yet can be used stably over a long time.SOLUTION: A motor valve 1 includes: a valve body 10; a valve stem 21 configured to be rotationally driven by a motor and displaced in an axial direction; a valve holder held by the valve stem 21; a first valve disc 24 fixed to the valve holder and including a through hole 24d; a second valve disc 25 disposed between the valve stem 21 and the first valve disc 24; an elastic body 26 which biases the first valve disc 24 in a direction away from the second valve disc 25; and a seal holder 29 including a holder base part disposed in the valve body 10. A space between an outer periphery of the holder base part and an inner periphery of the valve body 10 is sealed. An annular seal body OR is disposed between an inner periphery of the holder base part and an outer periphery of the valve holder. An orifice passage 11d and an internal space of the valve body 10 may communicate with each other through the through hole 24d in a state that the first valve disc 24 is seated on a valve seat 11e in a valve chamber VC, and the through hole 24d is closed when the second valve disc 25 comes in contact with the first valve disc 24.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] A motor-driven electric valve has a screw mechanism in which the male screw of a valve shaft, which is driven to rotate by a stepping motor, is screwed into a female screw hole provided in a valve body. This screw mechanism rotates the valve shaft around its axis and displaces it in the axial direction, thereby increasing or decreasing the gap between the valve body 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 flow rate when the valve is open. In such an electrically operated valve, when the valve is closed, it is necessary to suppress leakage of fluid from the valve chamber to the low-pressure piping at two points: between the valve disc seated on the valve seat and the valve seat, and between the O-ring that seals between the base member fixed to the valve body and the valve disc. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-65898 A Summary of the Invention [Problem to be solved by the invention]

[0005] Here, 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 will result in problems such as reduced sliding properties and increased motor load. Also, assuming long-term use, it is desirable to select a material for the O-ring that is less susceptible to deterioration due to heat, for example, but this also creates the problem of limiting the freedom of material selection.

[0006] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a motor-operated valve which is relatively inexpensive and can be used stably for a long period of time. [Means for solving the problem]

[0007] The motor-operated valve of the present invention comprises: a valve body including a valve seat, a valve chamber, and an orifice passage; a valve shaft that is rotationally driven by a motor and displaces in an axial direction; a valve holder held by the valve shaft; a first valve body fixed to the valve holder and having a through hole; a second valve body disposed between the valve stem and the first valve body; an elastic body that biases the second valve body in a direction away from the first valve body; a seal holder having a holder base disposed within the valve body; A gap between an outer periphery of the holder base and an inner periphery of the valve body is sealed, An annular seal is disposed between an inner periphery of the holder base and an outer periphery of the valve holder, When the first valve body is seated on the valve seat in the valve chamber, the orifice passage and an internal space of the valve body are capable of communicating with each other via the through hole, When the second valve body abuts against the first valve body, the through hole is closed. It is characterized by: Effect of the Invention

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

[0009] [Figure 1] FIG. 1 is a vertical cross-sectional view showing a motor-operated valve according to an embodiment of the present invention, in a closed state. [Diagram 2] FIG. 2 is a vertical cross-sectional view showing the motor-operated valve according to the embodiment of the present invention, in a partially open state. [Diagram 3] FIG. 3 is a vertical cross-sectional view showing the motor-operated valve according to the embodiment of the present invention, in a fully open state. [Figure 4]FIG. 4 is an enlarged view of the vicinity of the valve chamber of the motor-operated valve shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

[0011] Figures 1 to 3 are vertical 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 a 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 that is open at the 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 is formed by connecting a hollow cylindrical portion 10a and a bottom wall portion 10b. The thickness of the hollow cylindrical portion 10a and the bottom wall portion 10b are substantially equal. The inside of the hollow cylindrical portion 10a constitutes 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 constitutes a part of the valve body 10.

[0015] The valve seat member 11 is formed by connecting a hollow reduced diameter cylindrical portion 11a and a hollow expanded diameter cylindrical portion 11b in the direction of the axis L. The reduced diameter cylindrical portion 11a is fitted into the opening 10d and brazed. An end of the first pipe T1 is fitted into the inner periphery of the expanded diameter cylindrical portion 11b and connected 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 toward the bottom, and a cylindrical orifice passage 11d whose diameter is smaller than that of the upper opening 11c. The first pipe T1 is disposed 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 toward the top is formed on the inner circumference 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 an 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 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 integrated in a sealed state by being joined by welding. Also, 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 is 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 a 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 be configured to 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 circuit (not shown) via a substrate CB, a connector CN, and wiring HN. The substrate CB and the connector CN are covered with another resin cover 57. When the stator coil 53 is energized, the rotor 30 disposed in the can 45 can rotate about the axis L. The inside of the resin cover 57 is filled with a molding resin MR.

[0021] The guide stem 15 disposed inside the rotor 30 comprises a solid cylindrical body 15a and a hollow cylindrical portion 15b connected together. A female screw hole (female screw portion) 15c is formed in the body 15a so as to penetrate the center in the direction of the axis L. A flange-shaped disk 18 is fixed to the outer circumferential groove of the expanded diameter portion 15e on the lower end side of the hollow cylindrical portion 15b, and the guide stem 15 is fixed to the valve body 10 by welding the flange-shaped disk 18 to the upper end of the valve body 10 as described above. A pressure equalizing hole 15d is formed in the hollow cylindrical portion 15b so as to penetrate from the inner to the outer periphery.

[0022] 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 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 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 shaft 21 is made up of a small diameter section 21a fitted with an annular connector 32 attached to the rotor 30, a male thread section 21b that screws into the female threaded hole 15c of the guide stem 15, a valve shaft cylindrical section 21c formed below the male thread section 21b, an outer flange section 21d that extends radially outward from the lower end of the valve shaft cylindrical section 21c, and a small cylindrical section 21e that protrudes downward from the lower end of the valve shaft cylindrical section 21c. The outer diameter of the small cylindrical section 21e is smaller than that of the valve shaft cylindrical section 21c.

[0024] A valve-closing direction movable stopper 35 is screwed onto the upper end of the male thread 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] Furthermore, a valve-opening direction movable stopper 36 is screwed onto 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 FIG. 4, a valve holder 23 is attached to the lower end of the valve shaft 21. The valve holder 23 is formed by connecting an outer wall portion 23a and an inner flange portion 23b extending radially inward from the upper end of the outer wall portion 23a. The outer wall portion 23a has an inner circumference with a larger diameter than the outer flange portion 21d, and the inner flange portion 23b has an inner circumference with a smaller diameter than the outer flange portion 21d. A circular opening 23c that slidably fits into the valve shaft cylindrical portion 21c is formed in the center of the inner flange portion 23b. The outer periphery of the outer wall portion 23a slidably fits into the inner circumference of the hollow cylindrical portion 15b of the guide stem 15. In addition, a plurality of communication holes 23d that are arranged along the circumferential direction and penetrate in the radial direction are formed near the upper end of the outer wall portion 23a.

[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 is formed by connecting 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, and a tapered portion 24c, which decreases in diameter as it approaches downward, is formed at the lower end of the lower cylindrical portion 24b. In addition, a through hole 24d is formed in the first valve body 24, which penetrates vertically along the axis L. The through hole 24d communicates between a space on the valve shaft side (a middle chamber MC above the first valve body 24) and a space on the opposite valve shaft side (a space below the first valve body 24 connected to the orifice passage 11d) via a seal holder 29 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 portion 25b extending radially outward from an upper end of the valve body base 25a, and a hemispherical portion 25c formed at the lower end of the valve body base 25a and equipped with a spherical surface.

[0029] The coil spring (elastic body) 26 has its upper end abutted against the lower end of the valve body flange portion 25b, and its lower end abutted 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, enabling 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 is formed by connecting an annular holder base 29a, an annular holder flange portion 29b extending radially outward from the upper end of the holder base 29a, and a circular bottom wall portion 29c shifted from the lower end of the holder base 29a and extending radially outward (while being connected via a small cylindrical portion). An annular recess 29e is formed coaxially at the upper end of the holder base 29a (radially inside the holder flange portion 29b). An outer wall portion 23a of the valve holder 23 is slidably fitted into a holder opening 29d penetrating the bottom wall portion 29c, and the outer wall portion 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 side of the guide stem 15 is disposed facing 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 allowing 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 circumference 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 are relatively displaceable 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 partitioned 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 provide a 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 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, the valve shaft 21, the valve opening direction movable stopper 36, the valve holder 23, the washer 28, the thrust bearing 27, the second valve body 25, the coil spring 26, and the first valve body 24 are displaceable in the direction of the axis L relative to the guide stem 15 and the seal holder 29 fixed to the valve body 10. Also, the valve holder 23 and the first valve body 24 are displaceable in the direction of the axis L relative to the valve shaft 21. Furthermore, the second valve body 25 is displaceable in the direction of the axis L relative to the valve shaft 21 and the 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 with the flange-shaped disk 18 attached is joined to the seal holder 29 with the O-ring OR and sliding member SD attached to it to create a first assembly. The seal holder 29 may be welded to the flange-shaped disk 18 at this point, or may be welded simultaneously when welding the flange-shaped disk 18 to the valve body 10. This creates a seal between the seal holder 29 and the valve body 10 (i.e., the outer periphery of the holder base 29a and the inner periphery of the valve body 10).

[0039] Furthermore, after the washer 28 and the valve holder 23 are attached from the male thread portion 21b side of the valve shaft 21, the valve opening direction movable stopper 36 is screwed into 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 attached 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, the can 45, and the flange-shaped disk 18 are fixed by welding. Thereafter, the pipes T1 and T2 are brazed and the stator 50 is attached to the can 45, completing the motor-operated valve 1.

[0042] According to this embodiment, as shown in Fig. 4, a gap A (preferably a tight 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. Using this gap B, the valve holder 23 together with the seal holder 29 and the first valve body 24 can be adjusted in a direction perpendicular to the axis to center the valve shaft 21 and the valve seat member 11. Since the coaxiality of the guide stem 15 and the seal holder 29 is ensured by the accuracy of machining, if the seal holder 29 is installed 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, and fluid leakage can be suppressed.

[0043] (Operation of 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) has entered the valve chamber VC from the second pipe T2, and the motor-operated valve 1 is in the valve-closed state shown in Fig. 1. At this time, the lower end of the lowered valve stem 21 presses the upper end of the second valve body 25, so that the second valve body 25 descends 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 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 closed valve state, the tapered portion 24c is seated on the valve seat 11e, thereby preventing the fluid from flowing out from the valve chamber VC into the first pipe T1. Even if the fluid moves from the valve chamber VC to the intermediate chamber MC and the pressure in the intermediate chamber MC increases, the semispherical portion 25c closes the upper end of the through hole 24d, thereby preventing the 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 from this closed valve state, the rotor 30 and the valve shaft 21 are rotated 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 top and bottom is canceled), and the first valve body 24 is more likely to rise.

[0048] As the valve stem 21 rises, the outer flange portion 21d also rises, and the inner flange portion 23b is urged upward via the washer 28, causing the valve holder 23 to rise as if being lifted up, and the first valve body 24 moves away from the valve seat 11e, resulting in the fully open valve state shown in Fig. 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, so that wear resistance and sealing performance are ensured for a long period of time. In addition, the washer 28 slides against the outer flange portion 21d and the inner flange portion 23b when they rotate relative to each other, ensuring a low friction state.

[0049] As 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 is separated 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 side through 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. Also, the intermediate chamber MC communicates 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, from this fully open state, a pulse current with reverse characteristics is supplied to the stator 50 from an external power supply circuit, the rotor 30 and the valve shaft 21 are rotated 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 portion 21d also descends, which causes the valve holder 23 to also descend, so that the first valve body 24 seats on the valve seat 11e. This prevents fluid from passing between the first valve body 24 and the valve seat 11e from the valve chamber VC.

[0054] 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 shaft 21 and displaced against the biasing force of the coil spring 26, and 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, whereas the rotation of the valve shaft 21 continues. At this time, the thrust bearing 27 slides against the valve shaft 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 pulse 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 chamber VC to the orifice passage 11d when the valve is closed can be suppressed regardless of the tension of the O-ring OR, the influence of deterioration due to heat, etc. This makes it possible to use 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 freedom of selection of 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 moves from the communication hole 23d to the intermediate chamber MC, so that the pressure in the intermediate chamber MC becomes equal to the pressure in the valve chamber VC. Therefore, the second valve body 25 is subjected to a pressure difference between the pressure in the through hole 24d (low pressure) and the pressure in the intermediate chamber MC (high pressure). However, when the valve is opened, the second valve body 25 first opens the through hole 24d, so that the fluid in the intermediate chamber MC moves through the through hole 24d to the orifice passage 11d side 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 does not encounter any problems when it subsequently opens.

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

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

[0061] This specification includes the disclosure of the following inventions. (First aspect) a valve body including a valve seat, a valve chamber, and an orifice passage; a valve shaft that is rotationally driven by a motor and displaces in an axial direction; a valve holder held by the valve shaft; a first valve body fixed to the valve holder and having a through hole; a second valve body disposed between the valve stem and the first valve body; an elastic body that biases the second valve body in a direction away from the first valve body; a seal holder having a holder base disposed within the valve body; A gap between an outer periphery of the holder base and an inner periphery of the valve body is sealed, An annular seal is disposed between an inner periphery of the holder base and an outer periphery of the valve holder, When the first valve body is seated on the valve seat in the valve chamber, the orifice passage and an internal space of the valve body are capable of communicating with each other via the through hole, When the second valve body abuts against the first valve body, the through hole is closed. A motor-operated valve.

[0062] (Second aspect) When the valve stem is displaced toward the valve seat, 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, When the valve stem is displaced in a direction opposite 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. A first embodiment of the motor-operated valve.

[0063] (Third aspect) 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 and having a friction coefficient smaller than that of the O-ring. The motor-operated valve according to the first or second aspect,

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

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

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

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

Claims

1. a valve body including a valve seat, a valve chamber, and an orifice passage; a valve shaft that is rotationally driven by a motor and displaces in an axial direction; a valve holder held by the valve shaft; a first valve body fixed to the valve holder and having a through hole; a second valve body disposed between the valve stem and the first valve body; an elastic body that biases the second valve body in a direction away from the first valve body; a seal holder having a holder base disposed within the valve body; A gap between an outer periphery of the holder base and an inner periphery of the valve body is sealed, An annular seal is disposed between an inner periphery of the holder base and an outer periphery of the valve holder, When the first valve body is seated on the valve seat in the valve chamber, the orifice passage and an internal space of the valve body are capable of communicating with each other via the through hole, When the second valve body abuts against the first valve body, the through hole is closed. A motor-operated valve.

2. When the valve stem is displaced toward the valve seat, 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, When the valve stem is displaced in a direction opposite 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.

2. The motor-operated valve according to claim 1 .

3. 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 and having a friction coefficient smaller than that of the O-ring.

2. The motor-operated valve according to claim 1 .

4. When the first valve body is seated on the valve seat, the orifice passage can communicate with an intermediate chamber inside the valve holder through the through hole, and the annular seal body seals between the valve chamber and the intermediate chamber.

2. The motor-operated valve according to claim 1 .

5. The intermediate chamber communicates with a back pressure chamber in a can housing a rotor of the motor.

5. The motor-operated valve according to claim 4.

6. The second valve body has a spherical surface that blocks the through hole.

2. The motor-operated valve according to claim 1 .

Images