Flow control valve

Abstract

The present invention seeks to prevent the generation of an adverse situation in flow control. A valve core (27) has a needle straight portion (27C) and a second needle tapered portion (27D) on the outer side (27X) in the up and down directions, and on the other hand, a valve hole (31) has a flow control straight portion (30C) and an opposed tapered portion (30D) on the inner side (30X) in the up and down directions. The tapered angle (full angle) of the opposed tapered portion (30D) is the same as or slightly smaller than the second needle tapered portion (27D), and is inclined along the second needle tapered portion (27D).

Description

Technical Field

[0001] This invention relates to a flow control valve installed in a flow path to control the flow rate of a fluid. Background Technology

[0002] Conventionally, flow control valves are known as such flow control valves, which control the flow rate of fluid passing between the outer surface of the valve core and the inner surface of the valve orifice by moving the valve core along its axial direction (see, for example, Patent Document 1).

[0003] Prior art literature

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 8-170753 ( Figure 3 wait) Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] In the aforementioned conventional flow control valves, when the valve core vibrates radially with its outer surface facing the inner surface of the valve orifice, one or both of the outer surface of the valve core and the inner surface of the valve orifice may wear, resulting in adverse conditions in flow control.

[0008] Solution for solving the problem

[0009] The flow control valve of the present invention has a needle-shaped valve core fitted into a valve orifice in a partition wall that partially divides the flow path. The flow control valve moves the valve core axially to control the flow rate of fluid passing between the outer surface of the valve core and the inner surface of the valve orifice. The flow control valve has: a conical inner surface included in the inner surface of the valve orifice; and a conical outer surface included in the outer surface of the valve core, and facing from the inside relative to the conical inner surface, and inclined along the conical inner surface. Attached Figure Description

[0010] Figure 1 This is a cross-sectional view of the flow control valve of the present invention.

[0011] Figure 2 This is a cross-sectional view near the valve core.

[0012] Figure 3 This is a cross-sectional view near the valve core.

[0013] Figure 4 This is a cross-sectional view near the valve core.

[0014] Figure 5 It is a graph showing the relationship between PLS and the cross-sectional area of ​​the opening.

[0015] Figure 6 This is a cross-sectional view near the valve core.

[0016] Figure 7 This is a cross-sectional view near the valve core.

[0017] Figure 8 This is a cross-sectional view near the valve core. Detailed Implementation

[0018] The following is for reference Figures 1 to 8 The flow control valve 10 of the present invention will be described. Figure 1 The flow control valve 10 shown is a so-called "electric expansion valve," and it is driven by a motor 11 (stepper motor) to drive a shaft member 25 having a valve core 27. Hereinafter, for convenience, it will be referred to as... Figure 1 The vertical direction is defined as the vertical direction of the flow control valve 10 and its components, but the flow control valve 10 can be used in any orientation.

[0019] The motor 11 includes a stator 12 and a rotor 20. The stator 12 is formed by mounting an annular housing 12C, which houses a plurality of electromagnetic coils 12A, in the middle portion of a generally cylindrical valve body 13. The valve body 13 has: a cylindrical housing 13A with a bottom at one end; and an inner cylinder portion 13N, which extends through a through hole 13D formed in the bottom wall 13B of the cylindrical housing 13A. The upper opening 13C of the cylindrical housing 13A is closed by a cover 13F. The annular housing 12C is disposed at the lower end of the cylindrical housing 13A. It should be noted that the cylindrical housing 13A may also be open at both ends and closed between the cylindrical housing 13A and the inner cylinder portion 13N by other components.

[0020] An extension tube 15 is pressed into the upper part of the inner cylinder 13N. An internal thread 15N is formed on the inner surface of the lower part of the extension tube 15.

[0021] A partition wall 30 is provided at the lower end of the inner cylinder portion 13N, and a valve hole 31 is formed in the partition wall 30. A through hole 29 is formed in the inner cylinder portion 13N near the partition wall 30, penetrating the side wall, and a first connecting pipe 14A is installed in the through hole 29. In addition, a second connecting pipe 14X extending downward is installed on the lower surface of the partition wall 30. Thus, fluid can flow from the second connecting pipe 14X to the first connecting pipe 14A (or in the opposite direction) through the valve hole 31 of the partition wall 30. That is, the partition wall 30 separates the flow path 100 from the second connecting pipe 14X to the first connecting pipe 14A in the middle.

[0022] like Figure 1As shown, the rotor 20 includes a cylindrical permanent magnet 20A with a bottom at the upper end and a shaft member 25 that passes through and is fixed to the upper end wall of the permanent magnet 20A. The rotor 20 is rotatably housed inside the cylindrical housing 13A. A valve core receiving chamber 25U, which opens downward, is formed in the shaft member 25 at a position lower than the fixed portion that is fixed to the permanent magnet 20A. The valve core receiving chamber 25U houses the base end of a needle-shaped valve core member 26 that extends axially along the inner cylinder portion 13N and a compression coil spring 25D disposed at a position further inward than the base end of the valve core member 26. A cylindrical valve core anti-disengagement member 25T is fixed to the open end of the valve core receiving chamber 25U. The base end of the valve core member 26 extends laterally relative to the inner radial direction of the valve core anti-disengagement member 25T. The valve core member 26 is pushed downward by the compression coil spring 25D, thereby being pushed against the valve core anti-disengagement member 25T. The lower end (front end) of the valve core component 26 becomes the valve core 27.

[0023] An external thread 25A is formed on the lower part of the outer surface of the shaft member 25, which engages with the internal thread 15N of the extension tube 15. Thus, when the shaft member 25 rotates together with the permanent magnet 20A (i.e., the rotor 20 rotates), the shaft member 25 (i.e., the rotor 20) moves in the vertical direction, and the valve core 27 opens and closes the valve port 31 (see reference). Figure 2 as well as Figure 3 It should be noted that the valve core component 26 can either rotate together with the shaft component 25 or be configured not to rotate relative to the valve body 13. For example, a portion of the cross-section of the valve core component 26 can be made non-circular, and a non-circular through hole corresponding to the non-circular cross-section can be formed in the valve body 13.

[0024] A spiral guide 22 is fixed to the upper part of the fixing portion that is fixed to the permanent magnet 20A in the shaft member 25. The spiral guide 22 is formed by spirally winding a wire around the upper end of the shaft member 25. It should be noted that the upper end of the shaft member 25 is slit-machined, and a straight portion of the wire is inserted into it and tightened, thereby fixing the spiral guide 22 to the shaft member 25. Alternatively, the spiral guide 22 can also be fixed by having the upper end of the wire pass through the upper end of the shaft member 25 from the side.

[0025] A slider 23 engages with the helical guide 22. The slider 23 is annular, accommodating a portion of the gap between axially adjacent wires in the helical guide 22, and has a slider arm 23A extending laterally. Furthermore, the limiter 17 hangs parallel to the shaft member 25 from the cover 13F that closes the upper opening of the cylindrical housing 13A. With the slider arm 23A in contact with the slider 23, the slider 23 rotates relative to the helical guide 22 and moves up and down as the rotor 20 rotates, but cannot rotate when it reaches the upper or lower end of the helical guide 22. Thus, the amount of rotation of the rotor 20 (i.e., the linear motion of the valve core 27) is limited.

[0026] The flow control valve 10 controls the flow rate of refrigerant between the first connecting pipe 14A and the second connecting pipe 14X, for example, through the flow path 100 for refrigerant supplied to the vehicle's air conditioning system. Specifically, as... Figure 1 As shown, with the slider 23 restricted from rotating by the upper end of the helical guide 22, as... Figure 2 As shown, the valve core 27 of the valve core component 26 enters the valve hole 31 of the partition wall 30 and abuts against the valve seat 32, thereby closing the valve hole 31 and restricting the flow between the first connecting pipe 14A and the second connecting pipe 14X. Furthermore, as... Figure 3 As shown, the valve core 27 moves upward to open the valve orifice 31, thereby enabling flow between the first connecting pipe 14A and the second connecting pipe 14X.

[0027] The valve core 27 and valve orifice 31 will be described below. Figure 1 as well as Figure 2 As shown, the outer surface 27X of the valve core 27, from top to bottom, has a shaft portion 27A, a first needle tapered portion 27B (equivalent to the "abutment portion" in the technical solution), a needle straight portion 27C (equivalent to the "cylindrical outer surface" in the technical solution), a second needle tapered portion 27D (equivalent to the "conical outer surface" in the technical solution), and a third needle tapered portion 27E. The shaft portion 27A is a cylindrical surface with a constant outer diameter larger than the minimum inner diameter of the valve hole 31. The first needle tapered portion 27B extends from the lower end of the shaft portion 27A with a narrowing diameter. The needle straight portion 27C hangs down from the lower end of the first needle tapered portion 27B, and its axial length is about 1 / 3 to 1 / 5 of the axial length of the first needle tapered portion 27B. The second needle tapered portion 27D extends from the lower end of the needle straight portion 27C with a narrowing diameter, and its axial length is about 2 to 5 times the axial length of the first needle tapered portion 27B.

[0028] The cone angle of the first tapered portion 27B is different from that of the second tapered portion 27D, and the cone angle of the second tapered portion 27D is smaller than that of the first tapered portion 27B. For example, the cone angle (full angle) of the first tapered portion 27B is 40 to 60 degrees, while the cone angle (full angle) of the second tapered portion 27D is 1 to 10 degrees.

[0029] The third needle tapered portion 27E narrows in diameter from the lower end of the second needle tapered portion 27D at an angle larger than the cone angle of the first needle tapered portion 27B, and its axial length is approximately the same as the axial length of the needle straight portion 27C.

[0030] like Figures 2-4 As shown, the valve hole 31 penetrates the partition wall 30, and the upper end of the inner side of the partition wall 30 becomes the valve seat 32 (equivalent to the "abutment part" in the technical solution). The valve seat 32 is inclined at the same angle as the first needle tapered portion 27B or at a slightly larger angle (less than 10 degrees) than the first needle tapered portion 27B. The first needle tapered portion 27B of the valve core 27 approaches and separates from the valve seat 32, thereby closing and opening the valve hole 31.

[0031] The inner surface 30X of the partition wall 30 (the inner surface 30X of the valve hole 31) has an upper straight portion 30A, an upper tapered portion 30B, a flow control straight portion 30C (equivalent to the "cylindrical inner surface" in the technical solution), an opposing tapered portion 30D (equivalent to the "tapered inner surface" in the technical solution), and a lower tapered portion 30E below the valve seat 32. The upper tapered portion 30B extends from the lower end of the upper straight portion 30A with a narrowing diameter. The flow control straight portion 30C hangs downward from the lower end of the upper tapered portion 30B. The opposing tapered portion 30D narrows from the lower end of the flow control straight portion 30C and slopes along the second needle tapered portion 27D. For example, the cone angle (full angle) of the opposing tapered portion 30D is the same as or slightly smaller than that of the second needle tapered portion 27D (the difference is less than 1.0 degree, more preferably less than 0.5 degree). The axial length of the opposing tapered portion 30D is, for example, about 1.2 to 2 times the axial length of the flow control straight portion 30C.

[0032] In addition, the axial length of the flow control straight section 30C is greater than the axial length of the needle straight section 27C of the valve core 27 (about 1.2 times in this embodiment), and the axial length of the opposing tapered section 30D is smaller than the axial length of the second needle tapered section 27D of the valve core 27 (about 1 / 4 to 1 / 5 times in this embodiment).

[0033] The lower tapered portion 30E extends from the lower end of the opposing tapered portion 30D with an increased diameter. The axial length of the lower tapered portion 30E is approximately 4 to 5 times the axial length of the opposing tapered portion 30D.

[0034] like Figure 2 As shown, when the valve is closed, the first needle tapered portion 27B of the valve core 27 abuts against the valve seat 32, thereby closing the valve orifice 31. At this time, the lower part of the needle straight portion 27C of the valve core 27 has a gap and faces the upper end of the flow control straight portion 30C of the valve orifice 31, and the upper part of the second needle tapered portion 27D of the valve core 27 has a gap and faces the flow control straight portion 30C and the opposing tapered portion 30D of the valve orifice 31.

[0035] exist Figure 5 The flow control valve 10 is shown in the fully closed state (see reference). Figure 2 From ) to become fully open (refer to) Figure 4 The change in the cross-sectional area of ​​the opening up to the present. Figure 5 The horizontal axis of the graph uses the number of input pulses from motor 11 (stepper motor) to represent the linear movement position (valve opening) of valve core 27. In this graph, when the number of input pulses is "0", the front end of valve core 27 is at its most protruding position relative to valve orifice 31 (minimum valve opening). As the number of input pulses increases, the front end of valve core 27 retracts from valve orifice 31. Furthermore, the opening cross-sectional area refers to the cross-sectional area of ​​the minimum gap between valve orifice 31 and valve core 27; the fluid flow rate changes accordingly with the change in this opening cross-sectional area. In this embodiment, the distance by which valve core 27 moves relative to the operating angle of motor 11 for one step is 0.5 to 20 μm, enabling precise control of the valve core 27's position.

[0036] First, from the fully closed state (refer to...) Figure 2 As the valve opens, the opening cross-sectional area gradually increases as the gap between the valve seat 32 and the first needle cone portion 27B of the valve core 27 increases. Figure 5 *1). When the cross-sectional area of ​​the gap between the valve seat 32 and the first needle tapered portion 27B of the valve core 27 exceeds the cross-sectional area of ​​the gap between the needle straight portion 27C of the valve core 27 and the flow control straight portion 30C of the valve orifice 31, the opening cross-sectional area remains constant. Figure 5 ※2) Continue until the needle straight section 27C disengages from the flow control straight section 30C (see reference). Figure 6 ).

[0037] Furthermore, when the needle straight portion 27C disengages from the flow control straight portion 30C, the gap between the second needle tapered portion 27D of the valve core 27 and the flow control straight portion 30C gradually increases (see reference). Figure 3 The cross-sectional area of ​​the opening gradually increases again. Figure 5(※3 in the text). By changing the cross-sectional area of ​​the opening in this part, flow control in a small flow range can be achieved. When the moving distance of the valve core 27 in this range is set to L1, and the displacement of the shortest distance between the second needle cone 27D and the flow control straight part 30C is set to L2, it becomes 0 < L2 / L1 < 0.18. By making the cone angle of the second needle cone 27D smaller, the opening cross-sectional area can be precisely controlled.

[0038] When the second needle tapered section 27D disengages from the flow control straight section 30C (refer to...) Figure 7 The cross-sectional area of ​​the gap between the lower end of the second needle tapered portion 27D and the upper tapered portion 30B, the upper straight portion 30A of the valve hole 31, and the valve seat 32 becomes the opening cross-sectional area. Then, the opening cross-sectional area between the upper end of the valve seat 32 and the third needle tapered portion 27E of the valve core 27 becomes the opening cross-sectional area (see reference). Figure 8 Then, the entire valve core 27 disengages from the valve hole 31, becoming fully open (see reference). Figure 4 ).

[0039] However, in conventional flow control valves, for example, when the valve core vibrates radially due to the eccentric rotation of the rotor, wear can occur in the valve core or valve orifice. In particular, when the valve core 27 comes into contact with the edge portion of the flow control valve 10 of this embodiment, which forms an opening cross-sectional area in a small flow range, such as the boundary between the flow control straight portion 30C and the upper conical portion 30B, and the edge wears, malfunctions may occur in flow control within the small flow range.

[0040] In contrast, the flow control valve 10 according to this embodiment has an opposing tapered portion 30D on the inner surface of the valve orifice 31, which is substantially parallel to the second needle tapered portion 27D of the valve core 27. Therefore, when the valve core 27 vibrates radially, the valve core 27 (second needle tapered portion 27D) comes into surface contact with the opposing tapered portion 30D of the valve orifice 31. As a result, the valve core 27 or the valve orifice 31 is less prone to wear. In particular, line contact with the edge of the valve orifice 31 is suppressed, making the edge less prone to wear.

[0041] Furthermore, when the opposing tapered portion 30D of the valve orifice 31, which has approximately the same cone angle, abuts against the second needle tapered portion 27D of the valve core 27 to form a closed valve, there is a concern that the valve core 27 may bite into the valve orifice 31. However, since a first needle tapered portion 27B that abuts against the valve seat 32 is provided in addition to the second needle tapered portion 27D, which has an opening cross-sectional area in a small flow range, there is always a gap between the opposing tapered portion 30D and the second needle tapered portion 27D. Therefore, it is possible to prevent the valve core 27 from biting into the valve and to ensure the sealing performance when the valve is closed.

[0042] In addition, by providing a needle straight section 27C and a flow control straight section 30C in the valve core 27 and valve hole 31, the opening cross-sectional area is difficult to change even if the valve core 27 vibrates slightly in the axial and radial directions, thereby reducing the flow deviation in small flow ranges.

[0043] It is also considered that if the range of the inner surface of the valve orifice 31 being roughly parallel to the second needle tapered portion 27D of the valve core 27 is too large, the resistance during fluid flow may increase, resulting in adverse conditions in flow control. To address this, the axial length of the opposing tapered portion 30D of the valve orifice 31 is smaller than the axial length of the second needle tapered portion 27D. Therefore, although the structure is designed so that the valve core 27 (second needle tapered portion 27D) is in surface contact with the opposing tapered portion 30D of the valve orifice 31, the increase in resistance during fluid flow is suppressed.

[0044] Furthermore, when the cone angle of the second needle tapered portion 27D of the valve core 27 is equal to the cone angle of the opposing tapered portion 30D of the valve hole 31, the contact area between them increases, further suppressing wear on the valve core 27 or the valve hole 31. On the other hand, when the cone angle of the opposing tapered portion 30D is larger than the cone angle of the second needle tapered portion 27D, the valve core 27 is more likely to abut against the valve hole 31 on the smaller diameter side (lower side) compared to the larger diameter side (upper side). Therefore, the edge of the valve hole 31 (the boundary between the flow control straight portion 30C and the upper tapered portion 30B) is less prone to wear, allowing the flow control valve 10 to be used for a longer period of time.

[0045] [Other Implementation Methods]

[0046] (1) In the above embodiment, the valve core 27 and the valve hole 31 have a needle straight portion 27C and a flow control straight portion 30C, but they may not have these.

[0047] (2) In the above embodiment, the axial length of the opposing tapered portion 30D of the valve hole 31 is smaller than the axial length of the second needle tapered portion 27D, but it can also be the same or larger than the axial length of the second needle tapered portion 27D.

[0048] (3) In the above embodiment, the valve core 27 and the valve seat 32 abut against each other to close the valve. However, it can also be a structure in which there is a gap between the two and the fluid flows in a small amount when the valve core 27 enters the deepest part of the valve hole 31.

[0049] It should be noted that while specific examples of the technology included in the technical solutions are disclosed in this specification and accompanying drawings, the technology described in the technical solutions is not limited to these specific examples. It also includes solutions obtained by various modifications and alterations to the specific examples, as well as solutions obtained by extracting a portion of a specific example. Furthermore, the numerical values ​​in this specification are illustrative, and the technology described in the technical solutions is not limited to these numerical values.

Claims

1. A flow control valve having a needle-shaped valve core fitted into a valve orifice in a partition wall, the partition wall partially dividing a flow path, and the flow control valve controlling the flow rate of fluid passing between the outer surface of the valve core and the inner surface of the valve orifice by moving the valve core axially along the valve core, wherein... The flow control valve has: A tapered inner surface, which is contained within the inner surface of the valve orifice, and tapers towards the front end of the valve core; and A tapered outer surface, which is included in the outer surface of the valve core, narrows towards the front end of the valve core, and is opposed from the inside to the tapered inner surface, and is inclined along the tapered inner surface. The flow control valve includes an abutment portion, which is disposed in the valve core at a position closer to the larger diameter side than the outer conical surface and in the valve hole at a position closer to the larger diameter side than the inner conical surface. The abutment portions abut against each other to put the flow control valve in a closed state. In the closed valve state, there is a gap between the outer conical surface and the inner conical surface.

2. The flow control valve according to claim 1, wherein, The cone angle of the inner side of the cone is smaller than the cone angle of the outer side of the cone.

3. The flow control valve according to claim 1 or 2, wherein, When the movement distance of the valve core is set as L1, and the increase in the shortest distance between the outer and inner sides of the cone is set as L2, 0 < L2 / L1 < 0.18 The units for both L1 and L2 are mm.

4. The flow control valve according to claim 3, wherein, The flow control valve uses a stepper motor as its drive source. The valve core moves a distance of 0.5 to 20 μm relative to the stepper motor's one-step operating angle.

5. The flow control valve according to claim 1 or 2, wherein, The valve orifice increases in diameter as it approaches one end from the inner conical side, and further increases in diameter as it approaches the other end from the inner conical side. The axial length of the inner surface of the cone is smaller than the axial length of the outer surface of the cone.

6. The flow control valve according to claim 1 or 2, wherein, The outer diameter of the larger diameter end of the outer tapered surface is smaller than the inner diameter of the larger diameter end of the inner tapered surface. The outer surface of the valve core has a cylindrical outer surface near the large-diameter end of the tapered outer surface, and the cylindrical outer surface has the same outer diameter as the large-diameter end of the tapered outer surface or the outer diameter of the cylindrical outer surface is larger than that of the large-diameter end of the tapered outer surface.

7. The flow control valve according to claim 1, wherein, The outer diameter of the larger diameter end of the outer tapered surface is smaller than the inner diameter of the larger diameter end of the inner tapered surface. Near the large-diameter end of the conical inner surface in the inner surface of the valve hole, there is a cylindrical inner surface, the cylindrical inner surface has the same inner diameter as the large-diameter end of the conical inner surface or the inner diameter of the cylindrical inner surface is larger than that of the large-diameter end of the conical inner surface, and the cylindrical inner surface faces the outer side of the conical inner surface from the outside when the valve is closed.

Images