Electric valve

Abstract

Provided is an electrically operated valve capable of ensuring desired flow characteristics despite being easy to process and capable of reducing costs. In the electric valve, a valve core part of a valve shaft is provided with a large-diameter valve core cylinder part, a small-diameter valve core cylinder part which is smaller than the large-diameter valve core cylinder part, and a small-diameter cone part which is continuous with the small-diameter valve core cylinder part. The orifice portion of the valve body has a small-diameter orifice cylindrical portion and a large-diameter orifice cylindrical portion having a larger diameter than the small-diameter orifice cylindrical portion, and the small-diameter orifice cylindrical portion is positioned on the inside in the radial direction of the small-diameter orifice cylindrical portion when the valve shaft is in the restricting position, and the large-diameter orifice cylindrical portion is positioned on the outside in the radial direction of the small-diameter orifice cylindrical portion when the valve shaft is in the restricting position. When the valve shaft is displaced from the restricting position to the open position, the large-diameter valve body cylinder portion is separated from the inner side of the large-diameter orifice cylinder portion in the radial direction, and the large-diameter valve body cylinder portion is positioned on the inner side of the large-diameter orifice cylinder portion in the radial direction of the large-diameter orifice cylinder portion in the radial direction of the large-diameter orifice cylinder portion in the radial direction of the large-diameter orifice cylinder portion. The small-diameter valve body cylinder part is separated from the radial inner side of the small-diameter orifice cylinder part.

Description

Technical Field

[0001] The invention relates to an electric valve. Background Art

[0002] In the past, electric valves were used as devices, for example, arranged in a piping path of a fluid to open and close the flow path of the fluid and control the flow rate. In such electric valves, for example, as shown in Patent Document 1, a driving source such as a stepping motor installed in a valve body drives the valve core to ensure accurate flow control.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2017-180525

[0006] Technical problem to be solved by the invention

[0007] In an electric valve, it is sometimes desirable to perform valve opening control to maintain a small opening state immediately after the valve is opened so that a small flow rate of fluid flows. Even in such a small opening state, it is necessary to suppress the flow rate fluctuation of the fluid passing through the orifice.

[0008] In order to ensure stable flow control in a state of slight opening, an electric valve has been developed in which the inner periphery of the orifice is set to be an elongated cylindrical shape, and the outer periphery of the valve core in the orifice is set to be an elongated cylindrical shape. According to such an electric valve, when the valve core is relatively displaced along the axial direction relative to the orifice, the flow path cross-sectional area of ​​the gap formed between the orifice and the valve core is constant until the valve core is separated from the orifice, thereby stably controlling the flow rate of the fluid flowing through the gap.

[0009] However, in order to realize the above-mentioned structure, the inner periphery of the orifice and the outer periphery of the valve element facing thereto must be processed into a cylindrical shape with good accuracy within a certain distance, which requires labor for processing and increases the cost of the electric valve. Summary of the invention

[0010] An object of the present invention is to provide an electric valve that can ensure desired flow characteristics despite easy processing and reduced cost.

[0011] Technical means for solving technical problems

[0012] The electric valve according to the present invention is characterized by:

[0013] a valve body including a valve chamber and a throttle portion;

[0014] a valve shaft, the valve shaft being inserted into the throttle hole and having a valve core portion; and

[0015] a valve shaft drive unit that enables the valve shaft to be displaced relative to the valve body between a restricted position and an open position, wherein the restricted position is a position where the flow rate of the fluid passing through the throttle hole portion is the smallest, and the open position is a position where the flow rate of the fluid passing through the throttle hole portion is increased compared to the restricted position,

[0016] The valve core portion includes a large-diameter valve core cylindrical portion, a small-diameter valve core cylindrical portion having a smaller diameter than the large-diameter valve core cylindrical portion, and a small-diameter tapered portion continuous with the small-diameter valve core cylindrical portion.

[0017] The throttle hole portion includes a small-diameter throttle hole cylindrical portion and a large-diameter throttle hole cylindrical portion having a larger diameter than the small-diameter throttle hole cylindrical portion.

[0018] When the valve shaft is in the limiting position, the small-diameter valve core cylindrical portion is located radially inside the small-diameter throttle hole cylindrical portion, and the large-diameter valve core cylindrical portion is located radially inside the large-diameter throttle hole cylindrical portion.

[0019] When the valve shaft is displaced from the restricting position to the opening position, after the large-diameter valve core cylindrical portion is disengaged from the radial inner side of the large-diameter throttle hole cylindrical portion, the small-diameter valve core cylindrical portion is disengaged from the radial inner side of the small-diameter throttle hole cylindrical portion.

[0020] Effects of the Invention

[0021] According to the present invention, it is possible to provide an electric valve that can ensure desired flow rate characteristics despite easy processing and reduced cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a longitudinal sectional view showing the electric valve according to the first embodiment.

[0023] Figure 2 It is a diagram schematically showing the periphery of the orifice portion and the valve body portion of the electric valve according to the first embodiment.

[0024] Figure 3 This is a flow rate characteristic diagram of the electric valve according to the first embodiment, with the flow rate as the vertical axis and the valve opening (the axial position of the valve shaft) as the horizontal axis.

[0025] Figure 4 It means Figure 2 A cross-sectional view showing the periphery of a valve body portion and an orifice portion according to a comparative example for comparison.

[0026] Figure 5 It is a diagram schematically showing the periphery of an orifice portion and a valve body portion of an electric valve according to a second embodiment.

[0027] Figure 6This is a flow rate characteristic diagram of the electric valve according to the second embodiment, with the flow rate as the vertical axis and the valve opening (the axial position of the valve shaft) as the horizontal axis.

[0028] Explanation of symbols

[0029] 1 Electric valve

[0030] 10, 10A valve body

[0031] 13, 13A throttle hole

[0032] 20 Guide bushing

[0033] 23 External thread

[0034] 28 thread feed mechanism

[0035] 29 Lower stop mechanism

[0036] 33 Internal thread

[0037] 40, 40A valve shaft

[0038] 43, 43A valve core

[0039] 50 Stepper Motor

[0040] 51 rotor

[0041] 52 stator

[0042] VC valve chamber

[0043] T1 first catheter

[0044] T2 second catheter. DETAILED DESCRIPTION

[0045] Hereinafter, embodiments of the electric valve according to the present invention will be described with reference to the drawings.

[0046] [First embodiment]

[0047] Figure 1 It is a longitudinal sectional view showing the electric valve 1 according to the first embodiment. Figure 2 The diagram schematically shows the orifice portion and the valve core portion of the electric valve 1, and partially omits the diagram. The axis of the electric valve 1 is L. In this specification, the direction from the rotor toward the valve seat is referred to as downward, and the opposite direction is referred to as upward.

[0048] exist Figure 1In the embodiment, the electric valve 1 includes: a valve body 10, a guide bushing 20, a valve shaft holder 30, a valve shaft 40, a housing 55, a stepping motor 50 composed of a rotor 51 and a stator 52, a compression coil spring (biasing member) 60, a locking member 70, a screw feed mechanism 28, and a lower stop mechanism 29. In this embodiment, the valve shaft drive unit is composed of the stepping motor 50 and the screw feed mechanism 28.

[0049] The flange plate 18 is fixed to the upper end of the valve body 10 by brazing or the like. The lower end of the cylindrical housing 55 with a top surface abuts against a step portion provided on the outer periphery of the flange plate 18 and is sealed by welding.

[0050] The rotor 51 is rotatably arranged inside the housing 55 and outside the guide bushing 20 and the valve shaft holder 30, and the stator 52 for driving the rotor 51 to rotate is arranged outside the housing 55. The stator 52 is composed of a yoke 52a, a winding frame 52b, a stator coil 52c, and a resin molded cover 52d. A control signal including a drive pulse is input from the outside to the stator coil 52c via a substrate 52f connected to a lead wire 52g, and the rotor 51 arranged in the housing 55 rotates around the axis L at an angle corresponding to the drive pulse by excitation of the stator coil 52c.

[0051] The rotor 51 disposed in the housing 55 is fitted and supported by the valve shaft holder 30 , and the valve shaft holder 30 rotates integrally with the rotor 51 .

[0052] Specifically, the rotor 51 is a double tube structure consisting of an inner tube 51a, an outer tube 51b and a connecting portion 51c that connects the inner tube 51a and the outer tube 51b at a specified angular position around the axis L. A plurality of longitudinal grooves 51d are formed on the inner periphery of the inner tube 51a, extending in the direction of the axis L (up and down direction) at an angular interval of 120 degrees around the axis L, for example.

[0053] A plurality of ribs 30a extending vertically at 120-degree intervals about the axis L are protruded from the upper half of the outer periphery of the valve shaft holder 30. Upward locking surfaces (not shown) for supporting the rotor 51 are formed on both sides of the lower portion of the ribs 30a.

[0054] The longitudinal groove 51d of the inner tube 51a of the rotor 51 engages with the rib 30a of the valve shaft holder 30, and the lower surface of the inner tube 51a of the rotor 51 abuts against the locking surface of the valve shaft holder 30, so that the rotor 51 is supported and fixed in a state of being aligned with the valve shaft holder 30. Thus, the valve shaft holder 30 rotates together with the rotor 51 while supporting the rotor 51 in the housing 55.

[0055] A cylindrical locking member 70 is provided on the upper side of the rotor 51 and the valve shaft holder 30 to prevent relative movement of the valve shaft holder 30 and the rotor 51 in the lifting direction. The locking member 70 can press the rotor 51 downward relative to the valve shaft holder 30, and connect the valve shaft 40 and the valve shaft holder 30.

[0056] The upper portion of the locking member 70 is externally fixed to the upper end portion of the upper small diameter portion 41 of the valve shaft 40 by press-fitting, welding, etc. A flange-shaped rotor presser 72 is provided at the lower portion of the locking member 70. The rotor 51 is clamped between the valve shaft holder 30, which is urged upward by the force of the compression coil spring 60, and the rotor presser 72. In addition, the height from the upper end of the valve shaft holder 30 to the locking surface in the vertical direction is the same as the height of the inner tube 51a of the rotor 51 in the vertical direction, and the upper surface of the top 32 of the valve shaft holder 30 abuts against the lower surface of the rotor presser 72.

[0057] A return spring 75 composed of a coil spring is installed outside the outer periphery of the locking member 70. If the valve shaft holder 30 excessively displaces upward relative to the guide bushing 20 when the valve is opened, and the screwing engagement between the external threaded portion 23 of the guide bushing 20 and the internal threaded portion 33 of the valve shaft holder 30 is released, the return spring 75 applies force to the valve shaft holder 30 toward the guide bushing 20 to restore the screwing engagement between the external threaded portion 23 of the guide bushing 20 and the internal threaded portion 33 of the valve shaft holder 30.

[0058] The valve shaft 40 formed of a metal material has, from the upper side, an upper small diameter portion 41, an intermediate large diameter portion 42 having a larger diameter than the upper small diameter portion 41, and a valve core portion 43. The structure of the valve core portion 43 will be described below.

[0059] The guide bushing 20 is connected to a thin-walled cylindrical portion 22, a thick-walled cylindrical portion 21, and a base 27. The outer diameters of the thin-walled cylindrical portion 22 and the thick-walled cylindrical portion 21 are equal, and the outer diameter of the base 27 is larger than them. The intermediate large diameter portion 42 of the valve shaft 40 is inserted into the thick-walled cylindrical portion 21 in a state where it can move (slide) relatively along the axis L direction and can rotate relatively around the axis L. The inner diameter of the thin-walled cylindrical portion 22 extending upward from the upper end of the thick-walled cylindrical portion 21 is larger than that of the thick-walled cylindrical portion 21, and the upper end side of the intermediate large diameter portion 42 of the valve shaft 40 and the lower end side of the upper small diameter portion 41 are inserted into the thin-walled cylindrical portion 22.

[0060] An external threaded portion 23 is formed on the outer periphery of the thick cylindrical portion 21 of the guide bushing 20. In addition, a base portion 27, which is a portion below the external threaded portion 23 of the thick cylindrical portion 21, is fitted into the fitting hole 14 of the valve body 10 by press-fitting. A lower stopper 25 is screwed and fixed to an upper surface 27a of the base portion 27 with a predetermined gap on the lower side of the valve shaft holder 30 in the external threaded portion 23. A fixed stopper 24 is integrally provided protrudingly on the outer periphery of the lower stopper 25.

[0061] The valve shaft holder 30 includes a cylindrical portion 31 into which the guide bushing 20 is inserted and a top portion 32. An insertion hole 32a is provided through the top portion 32, through which the upper end portion of the upper small diameter portion 41 of the valve shaft 40 is inserted. An internal thread portion 33 is formed on the inner periphery of the cylindrical portion 31 of the valve shaft holder 30, which is screwed with the external thread portion 23 of the guide bushing 20 and constitutes a thread feed mechanism 28. The thread feed mechanism 28 is a mechanism that converts the rotational displacement of the rotor 51 relative to the valve body 10 into the axial displacement of the valve shaft 40.

[0062] A movable stopper 34 is integrally provided at the lower end of the outer circumference of the cylindrical portion 31 of the valve shaft holder 30. The fixed stopper 24 and the movable stopper 34 constituting the lower stopper mechanism 29 are locked with each other when the valve shaft holder 30 is lowered by a predetermined amount, thereby limiting the rotation and lowering of the valve shaft holder 30 and the valve shaft 40 connected to the valve shaft holder 30.

[0063] In addition, a compression coil spring (biasing member) 60 is installed between the inner step surface formed between the upper small diameter portion 41 and the middle large diameter portion 42 of the valve shaft 40 and the lower surface of the top portion 32 of the valve shaft holder 30. The compression coil spring 60 always urges the valve shaft 40 downward (valve closing direction) relative to the valve shaft holder 30.

[0064] The valve body 10 is formed of a metal cylinder such as brass or SUS. The valve body 10 has a valve chamber VC for introducing and discharging fluid therein, and the first conduit T1 is fixed to a first lateral opening 10a provided on the inner periphery of the valve chamber VC by brazing or the like. A partition wall 11 extending radially inward is formed in the middle position in the direction of the axis L of the valve body 10, and a through hole 11a is formed in the center of the partition wall 11 for connecting the fitting hole 14 and the valve chamber VC, and the middle large diameter portion 42 of the valve shaft 40 can be slidably inserted into the through hole 11a.

[0065] The bottom wall 12 of the valve body 10 has an orifice 13 formed inside thereof corresponding to the valve core 43 of the valve shaft 40 . The second pipe T2 is fixed to an annular recess 10 b formed on the lower surface of the bottom wall 12 by brazing or the like.

[0066] exist Figure 3The throttle hole portion 13 includes: a first throttle hole cylindrical portion (small diameter throttle hole cylindrical portion) 13a, a second throttle hole cylindrical portion (large diameter throttle hole cylindrical portion) 13b which is formed to communicate with the upper side of the first throttle hole cylindrical portion 13a and has an axial length shorter than that of the first throttle hole cylindrical portion 13a, and an annular upper step portion 13f (at the top of the second throttle hole cylindrical portion 13b) formed around the upper end of the second throttle hole cylindrical portion 13b. Figure 2 The valve seat 13d is formed at the intersection of the first throttle cylinder 13a and the upper step 13f. Preferably, the first throttle cylinder 13a is cut by a drill or the like, and the second throttle cylinder 13b having a larger diameter than the first throttle cylinder 13a is cut by a milling cutter or the like (i.e., in other processes).

[0067] On the other hand, the valve core portion 43 has: a first valve core conical portion (large diameter conical portion) 43a formed at the lower end of the middle large diameter portion 42 and decreasing in diameter as it moves downward, a first valve core cylindrical portion (large diameter valve core cylindrical portion) 43b connected to the first valve core conical portion 43a, a second valve core cylindrical portion (small diameter valve core cylindrical portion) 43d connected to the first valve core cylindrical portion 43b and having an axial length longer than that of the first valve core cylindrical portion 43b, and a third valve core conical portion (small diameter conical portion) 43e connected to the second valve core cylindrical portion 43d. The third valve core conical portion 43e may be a conical portion of two-stage shapes with different cone angles (in Figure 2 Preferably, the valve core portion 43 is formed by lathe processing.

[0068] Here, if the outer diameter of the second valve core cylindrical portion 43d is set to B1 and the inner diameter of the first throttle hole cylindrical portion 13a is set to B2, the cross-sectional area Δ1 of the gap between the second valve core cylindrical portion 43d and the first throttle hole cylindrical portion 13a can be expressed by Δ1=π((B2) 2 -(B1) 2 ) / 4.

[0069] In addition, if the outer diameter of the first valve core cylindrical portion 43b is set to B3 and the inner diameter of the second throttle hole cylindrical portion 13b is set to B4, the cross-sectional area Δ2 of the gap between the first valve core cylindrical portion 43b and the second throttle hole cylindrical portion 13b can be expressed by Δ2=π((B4) 2 -(B3) 2 Here, it is preferred that Δ1<Δ2.

[0070] Furthermore, when the valve is closed, when the distance from the contact point between the valve seat 13d and the first valve core conical portion 43a to the lower end of the first valve core cylindrical portion 43b is set to A1, and the distance from the upper end of the second throttle hole cylindrical portion 13b to the lower end of the second valve core cylindrical portion 43d is set to A2, it is preferred that A1≤A2.

[0071] (Electric valve operation)

[0072] The operation of the electric valve 1 will be described. Figure 3 The flow characteristic diagram of the electric valve 1 is represented by the flow rate as the vertical axis and the valve opening (the axial position of the valve shaft) as the horizontal axis, schematically showing the positional relationship between the valve core portion 43 and the orifice portion 13. The valve opening is proportional to the driving pulse of the control signal applied to the stator coil 52c. In addition, in this embodiment, Figure 3 The position P0 is equivalent to the limit position, exceeding Figure 3 The position P0 corresponds to the open position. In addition, before the large-diameter valve core cylinder is about to separate from the radial inner side of the large-diameter throttle hole cylinder, the lower end of the large-diameter valve core cylinder is located radially inside the large-diameter throttle hole cylinder. In addition, before the small-diameter valve core cylinder is about to separate from the small-diameter throttle hole cylinder, the lower end of the small-diameter valve core cylinder is located radially inside the small-diameter throttle hole cylinder.

[0073] Assume that the electric valve 1 is in Figure 1 In the valve closing state shown in FIG. 1 , the first valve core conical portion 43a of the valve core portion 43 is seated on the valve seat 13d ( Figure 3 At this time, the second valve core cylindrical portion 43d is located radially inside (overlapping in the axial direction) of the first throttle hole cylindrical portion 13a, and the first valve core cylindrical portion 43b is located radially inside (overlapping in the axial direction) of the second throttle hole cylindrical portion 13b. From this state, a control signal including a drive pulse is supplied to excite the stator coil 52c of the stator 52, and when the rotor 51 rotates in one direction, the valve shaft holder 30 and the valve shaft 40 rotate integrally with the rotor 51. This rotation is converted into an axial displacement of the valve shaft 40 by the screw feed mechanism 28, and the valve shaft 40 rises together with the valve core portion 43.

[0074] As the valve shaft 40 rises, the second valve core cylindrical portion 43d is displaced in the axial direction relative to the first throttle hole cylindrical portion 13a, and the first valve core cylindrical portion 43b is displaced in the axial direction relative to the second throttle hole cylindrical portion 13b. As a result, the first valve core conical portion 43a is separated from the valve seat 13d to generate a minimum gap exceeding 0, so that the refrigerant or other fluid flows from the valve chamber VC through the valve core portion 43 and the throttle hole portion 13 to the second conduit T2 through the minimum gap. When the minimum gap between the first valve core conical portion 43a and the valve seat 13d is small (from Figure 3From position P0 to position P1), the throttled area between the valve core portion 43 and the throttling hole portion 13, that is, the area with the smallest flow path area (referred to as the throttling area) becomes the area equivalent to the minimum gap between the first valve core cone portion 43a and the valve seat 13d, so as the minimum gap increases, the flow rate of the passing fluid increases linearly.

[0075] When the flow path cross-sectional area in the minimum gap between the first valve core conical portion 43a and the valve seat 13d exceeds the cross-sectional area Δ1 ( Figure 3 At position P1), the throttling area between the valve core portion 43 and the throttling hole portion 13 becomes a portion equivalent to the gap between the second valve core cylindrical portion 43d and the first throttling hole cylindrical portion 13a. Since the outer periphery of the second valve core cylindrical portion 43d and the inner periphery of the first throttling hole cylindrical portion 13a are both cylindrical in shape, the cross-sectional area Δ1 of the throttling area does not change even if the valve shaft 40 is displaced. However, the second valve core cylindrical portion 43d and the first throttling hole cylindrical portion 13a are relatively displaced in the direction of the axis L, and the first valve core cylindrical portion 43b and the second throttling hole cylindrical portion 13b are relatively displaced in the direction of the axis L, so that the overlapping range of each gradually narrows, thereby gradually reducing the pressure loss between the valve core portion 43 and the throttling hole portion 13, and thus the flow rate of the fluid passing through the throttling area gradually increases ( Figure 3 The range from position P1 to position P2).

[0076] exist Figure 3 In the position P2 shown, since the first valve core cylinder portion 43b is separated from the second throttle hole cylinder portion 13b (the first valve core cylinder portion 43b is no longer located radially inside the second throttle hole cylinder portion 13b), the gap between the first valve core cylinder portion 43b and the second throttle hole cylinder portion 13b has nothing to do with the pressure loss. However, at this time, since the second valve core cylinder portion 43d has not been separated from the first throttle hole cylinder portion 13a (the second valve core cylinder portion 43d is located radially inside the first throttle hole cylinder portion 13a), the throttling area is still a portion equivalent to the gap between the second valve core cylinder portion 43d and the first throttle hole cylinder portion 13a. Therefore, through the rise of the valve shaft 40, the second valve core cylinder portion 43d and the first throttle hole cylinder portion 13a are relatively displaced along the axis L direction, so that the overlapping range gradually narrows, thereby further reducing the pressure loss between the valve core portion 43 and the throttle hole portion 13, so that the flow rate of the fluid passing through the throttling area gradually increases ( Figure 3 From position P2 to position P3). Due to the difference in pressure loss of the orifice 13, Figure 3 The flow rate increase rate from position P2 to position P3 is Figure 3 The flow rate increase rate from position P1 to position P2 is high.

[0077] exist Figure 3At the position P3 shown, since the second valve core cylindrical portion 43d is separated from the first throttle hole cylindrical portion 13a (the second valve core cylindrical portion 43d is no longer located radially inside the first throttle hole cylindrical portion 13a), the gap between the third valve core conical portion 43e and the upper end of the first throttle hole cylindrical portion 13a becomes the throttling area, and the flow rate of the fluid between the valve core portion 43 and the throttle hole portion 13 increases linearly with the rise of the valve shaft 40, so that flow rate regulation becomes possible. Subsequently, the valve shaft 40 rises and reaches a fully open valve state (not shown).

[0078] On the other hand, from the fully open valve state, a control signal of opposite characteristics is supplied to excite the stator coil 52c of the stator 52 and rotate the rotor 51 in the opposite direction. The valve shaft holder 30 and the valve shaft 40 rotate integrally with the rotor 51, and the displacement in the axial direction of the valve shaft 40 is converted by the screw feed mechanism 28. The valve shaft 40 and the valve core 43 are lowered together, forming a Figure 1 The valve is shown in closed state.

[0079] Figure 4 4 is a cross-sectional view showing the periphery of the valve core portion 43' and the orifice portion 13' of the valve core 40' of the comparative example. Figure 4 In the embodiment, the valve core portion 43' includes a first valve core conical portion 43a', a valve core cylindrical portion 43b', and a second valve core conical portion 43c'. In addition, the orifice portion 13' includes an orifice cylindrical portion 13a' and a valve seat 13d'.

[0080] In addition, if the outer diameter of the valve core cylindrical portion 43b' is set to B5 and the inner diameter of the orifice cylindrical portion 13a' is set to B6, the cross-sectional area Δ3 of the gap between the valve core cylindrical portion 43b' and the orifice cylindrical portion 13a' can be expressed by Δ3=π((B6) 2 -(B5) 2 Here, it is preferred that Δ2>Δ1>Δ3 holds.

[0081] Furthermore, when the valve is closed, the distance from the contact point between the valve seat 13d' and the first valve body conical portion 43a' to the lower end of the valve body cylindrical portion 43b' is defined as A3. Preferably, A1≤A2<A3, and preferably, A1+A2≥A3.

[0082] Here, the valve core cylindrical portion 43b' and the orifice cylindrical portion 13a' are both formed by cutting, so there is a deviation in the cross-sectional area Δ3 due to component tolerance. Taking this deviation into consideration, when a small amount of fluid is to be stably flowed at a small opening, the distance A3 needs to be ensured to be longer, but the number of driving pulses required at a small opening increases, making flow control difficult. In addition, the length of the drill bit for cutting the orifice cylindrical portion 13a' becomes longer relative to the diameter, thereby increasing the difficulty of processing.

[0083] In contrast, according to the present embodiment, since the throttle portion 13 has the first throttle cylindrical portion 13a and the second throttle cylindrical portion 13b, the length of the drill bit for cutting the first throttle cylindrical portion 13a can be shortened, making the processing easier and improving the yield rate. In addition, the time from when the valve is closed to when the first valve core cylindrical portion 43b is separated from the second throttle cylindrical portion 13b can be reduced ( Figure 3 The number of drive pulses up to position P2) makes flow rate control easy.

[0084] [Second embodiment]

[0085] Figure 5 It is a longitudinal sectional view showing an electric valve 1A according to a second embodiment. Figure 6 It is a flow characteristic diagram of the electric valve 1A, with the flow rate as the vertical axis and the valve opening (the axial position of the valve shaft) as the horizontal axis, schematically showing the positional relationship between the valve core portion 43A and the throttling hole portion 13A. The electric valve 1A of this embodiment is called a so-called non-closed valve type that does not completely close the valve. Only the valve core portion 43A of the valve shaft 40A and the throttling hole portion 13A of the valve body 10A are different from the first embodiment. The same symbols are given to the same structures as the first embodiment, and repeated descriptions are omitted. Among them, in this embodiment, Figure 6 Positions P4 to P5 are equivalent to the limit positions. Figure 6 The position P5 corresponds to the open position.

[0086] The orifice portion 13A includes: a first orifice cylindrical portion 13Aa, a second orifice cylindrical portion 13Ab formed to communicate with the upper portion of the first orifice cylindrical portion 13Aa and having an axial length shorter than that of the first orifice cylindrical portion 13Aa, an annular upper step portion 13Af formed around the upper end of the second orifice cylindrical portion 13Ab, and an orifice tapered portion 13Ac formed to communicate with the lower portion of the first orifice cylindrical portion 13Aa and expanding in diameter as it moves downward. However, in the present embodiment, the intersection of the first orifice cylindrical portion 13Aa and the upper step portion 13Af does not constitute a valve seat.

[0087] On the other hand, the valve core portion 43A has: a first valve core cylindrical portion 43Ab connected to the lower end of the intermediate large diameter portion 42 of the valve shaft 40A, a second valve core cylindrical portion 43Ad connected to the first valve core cylindrical portion 43Ab and having an axial length longer than that of the first valve core cylindrical portion 43Ab, and a third valve core conical portion 43Ae connected to the second valve core cylindrical portion 43Ad. The third valve core conical portion 43Ae may be a conical portion of a two-stage shape with different cone angles. However, the first valve core conical portion is not formed between the intermediate large diameter portion 42 and the first valve core cylindrical portion 43Ab, and the boundary between the two becomes a step surface 43Af.

[0088] When the electric valve 1A is in Figure 5 When the valve is in the minimum open state shown (equivalent to Figure 6 At positions P4 to P5), the step surface 43Af does not contact the bottom wall 12A, and a predetermined gap is formed between the two. At this time, the second valve core cylinder 43Ad is located radially inside the first throttle hole cylinder 13Aa, and the first valve core cylinder 43Ab is located radially inside the second throttle hole cylinder 13Ab. Therefore, the throttling portion of the valve core 43A and the throttle hole 13A becomes a portion equivalent to the gap between the second valve core cylinder 43Ad and the first throttle hole cylinder 13Aa. Therefore, even if the valve shaft 40A is moved from Figure 6 The flow rate does not change even when the valve core 43A and the orifice 13A start to decrease from the position P4 (minimum valve opening state) to the position P5 where the pressure loss of the valve core 43A and the orifice 13A begins to decrease.

[0089] When the valve shaft 40A further rises, similarly to the first embodiment, Figure 6 At the position P6 shown in FIG. 1 , the first valve core cylindrical portion 43Ab is separated from the second throttle hole cylindrical portion 13Ab (the first valve core cylindrical portion 43Ab is no longer located radially inside the second throttle hole cylindrical portion 13Ab). Figure 6 In the position P7 shown, the second valve core cylinder portion 43Ad is detached from the first throttling hole cylinder portion 13Aa (the second valve core cylinder portion 43Ad is no longer located radially inside the first throttling hole cylinder portion 13Aa), so while the valve shaft 40A rises, the flow rate of the fluid through the valve core portion 43A and the throttling hole portion 13A increases, as in the first embodiment.

[0090] That is, when the valve shaft 40A moves from the restricting position to the open position (from position P5 to position P7), the gap between the second valve core cylinder portion 43Ad and the first throttling hole cylinder portion 13Aa forms a throttling area until the second valve core cylinder portion 43Ad disengages from the radial inner side of the first throttling hole cylinder portion 13Aa.

[0091] In addition, the present invention is not limited to the above-mentioned embodiment. Any constituent elements of the above-mentioned embodiment can be modified within the scope of the present invention. In addition, any constituent element can be added or omitted in the above-mentioned embodiment.

[0092] This specification contains the following invention contents.

[0093] (First method)

[0094] An electric valve is characterized by having:

[0095] a valve body including a valve chamber and a throttle portion;

[0096] a valve shaft, the valve shaft being inserted into the throttle hole and having a valve core portion; and

[0097] a valve shaft drive unit that enables the valve shaft to be displaced relative to the valve body between a restricted position and an open position, wherein the restricted position is a position where the flow rate of the fluid passing through the throttle hole portion is the smallest, and the open position is a position where the flow rate of the fluid passing through the throttle hole portion is increased compared to the restricted position,

[0098] The valve core portion includes a large-diameter valve core cylindrical portion, a small-diameter valve core cylindrical portion having a smaller diameter than the large-diameter valve core cylindrical portion, and a small-diameter tapered portion continuous with the small-diameter valve core cylindrical portion.

[0099] The throttle hole portion includes a small-diameter throttle hole cylindrical portion and a large-diameter throttle hole cylindrical portion having a larger diameter than the small-diameter throttle hole cylindrical portion.

[0100] When the valve shaft is in the limiting position, the small-diameter valve core cylindrical portion is located radially inside the small-diameter throttle hole cylindrical portion, and the large-diameter valve core cylindrical portion is located radially inside the large-diameter throttle hole cylindrical portion.

[0101] When the valve shaft is displaced from the restricting position to the opening position, after the large-diameter valve core cylindrical portion is disengaged from the radial inner side of the large-diameter throttle hole cylindrical portion, the small-diameter valve core cylindrical portion is disengaged from the radial inner side of the small-diameter throttle hole cylindrical portion.

[0102] (Second method)

[0103] The first aspect of the electric valve is characterized in that:

[0104] When the valve shaft is displaced from the limiting position to the opening position, after the small-diameter valve core cylindrical portion is separated from the radial inner side of the small-diameter throttle cylindrical portion, a gap between the end of the small-diameter throttle cylindrical portion and the small-diameter tapered portion forms a throttling area.

[0105] (Third Method)

[0106] The electric valve of the first or second aspect is characterized in that:

[0107] The valve core portion has a large-diameter cone portion, and the throttle hole portion has a valve seat. In the limiting position, the large-diameter cone portion is seated on the valve seat.

[0108] (Fourth Method)

[0109] The third aspect of the electric valve is characterized in that:

[0110] When the valve shaft displaces from the limiting position to the opening position, after the flow path cross-sectional area between the small-diameter valve core cylindrical portion and the small-diameter throttling hole cylindrical portion exceeds the flow path cross-sectional area between the large-diameter cone portion and the valve seat, the gap between the small-diameter valve core cylindrical portion and the small-diameter throttling hole cylindrical portion forms a throttling area.

[0111] (Fifth Method)

[0112] The electric valve of the first or second aspect is characterized in that:

[0113] At the restricted position, the valve core portion is not in contact with the orifice portion.

[0114] (Sixth Method)

[0115] The fifth aspect of the electric valve is characterized in that

[0116] When the valve shaft is displaced from the limiting position to the opening position, a gap between the small-diameter valve core cylindrical portion and the small-diameter throttle hole cylindrical portion forms a throttling area until the small-diameter valve core cylindrical portion is separated from the radial inner side of the small-diameter throttle hole cylindrical portion.

Claims

1. An electric valve, characterized in that: have: a valve body including a valve chamber and an orifice portion; a valve shaft, the valve shaft being inserted into the throttle hole and having a valve core portion; and a valve shaft drive unit that enables the valve shaft to be displaced relative to the valve body between a restricted position and an open position, wherein the restricted position is a position where the flow rate of the fluid passing through the throttle hole portion is the smallest, and the open position is a position where the flow rate of the fluid passing through the throttle hole portion is increased compared to the restricted position, The valve core portion includes a large-diameter valve core cylindrical portion, a small-diameter valve core cylindrical portion having a smaller diameter than the large-diameter valve core cylindrical portion, and a small-diameter tapered portion continuous with the small-diameter valve core cylindrical portion. The throttle hole portion includes a small-diameter throttle hole cylindrical portion and a large-diameter throttle hole cylindrical portion having a larger diameter than the small-diameter throttle hole cylindrical portion. When the valve shaft is in the limiting position, the small-diameter valve core cylindrical portion is located radially inside the small-diameter throttle hole cylindrical portion, and the large-diameter valve core cylindrical portion is located radially inside the large-diameter throttle hole cylindrical portion. When the valve shaft is displaced from the restricting position to the opening position, after the large-diameter valve core cylindrical portion is disengaged from the radial inner side of the large-diameter throttle hole cylindrical portion, the small-diameter valve core cylindrical portion is disengaged from the radial inner side of the small-diameter throttle hole cylindrical portion.

2. The electric valve according to claim 1, characterized in that: When the valve shaft is displaced from the limiting position to the opening position, after the small-diameter valve core cylindrical portion is separated from the radial inner side of the small-diameter throttle cylindrical portion, a gap between the end of the small-diameter throttle cylindrical portion and the small-diameter tapered portion forms a throttling area.

3. The electric valve according to claim 2, characterized in that: The valve core portion has a large-diameter cone portion, and the throttle hole portion has a valve seat. In the limiting position, the large-diameter cone portion is seated on the valve seat.

4. The electric valve according to claim 3, characterized in that: When the valve shaft displaces from the limiting position to the opening position, after the flow path cross-sectional area between the small-diameter valve core cylindrical portion and the small-diameter throttling hole cylindrical portion exceeds the flow path cross-sectional area between the large-diameter cone portion and the valve seat, the gap between the small-diameter valve core cylindrical portion and the small-diameter throttling hole cylindrical portion forms a throttling area.

5. The electric valve according to claim 2, characterized in that: At the restricted position, the valve core portion is not in contact with the orifice portion.

6. The electric valve according to claim 5, characterized in that: When the valve shaft is displaced from the limiting position to the opening position, a gap between the small-diameter valve core cylindrical portion and the small-diameter throttle hole cylindrical portion forms a throttling area until the small-diameter valve core cylindrical portion is separated from the radial inner side of the small-diameter throttle hole cylindrical portion.

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