JP4668755B2 - Solenoid proportional valve - Google Patents

Description

  The present invention relates to an electromagnetic proportional valve, and more particularly to an electromagnetic proportional valve used in an analyzer or the like that needs to perform a very small flow rate control with high accuracy.

  An electromagnetic proportional valve is known as a flow control valve used in an analyzer such as chromatography. As this type of electromagnetic proportional valve, a valve housing, a valve housing having a valve port, and a linear electromagnetic actuator including a plunger movably provided in an axial direction in a plunger tube attached to the valve housing; A valve body provided in the valve chamber and connected to the plunger, the valve body changing an opening degree of the valve port according to an axial direction of the plunger, and being incorporated between the plunger and the connection body of the valve body and the valve housing; A plate spring, and an axial movement position of the valve body is determined by an equilibrium relationship between an electromagnetic force generated by the electromagnetic actuator and a spring force of the leaf spring, thereby determining an opening / closing position of the valve body, Some perform flow rate control in proportion to the current supplied to the electromagnetic actuator (for example, Patent Documents 1 and 2).

  In the electromagnetic proportional valve described above, there is no variation in flow control among individuals, and in order to perform stable and highly accurate flow control of a small amount, the spring load characteristic that the leaf spring incorporated in the electromagnetic proportional valve gives to the coupling body It is important that there is no variation, and that the spring load applied to the coupling body by the leaf spring during the flow rate control operation does not fluctuate irregularly and has continuity.

  On the other hand, in the conventional electromagnetic proportional valve, the leaf spring is fixed to the valve housing by using a fixing ring on the outer edge side and fixedly coupled to the valve body by caulking or the like on the inner edge side. There may be variations in the initial spring load characteristics due to variations in the fixed state (assembly error). As a result, with the conventional electromagnetic proportional valve, the flow rate control characteristics vary from one individual to another, and it is not possible to perform a stable and highly accurate minute amount flow rate control.

  In addition, since there is an inevitable radial clearance between the plunger tube and the plunger due to the axial movement of the plunger, the flow control characteristics are improved by the plunger moving irregularly due to external vibration. Not stable.

  On the other hand, by setting the ratio of the plunger length (axial length) H to the diameter W to 2: 1 to 3: 1, preferably 2.4: 1 to 2.9: 1. In some cases, the flow rate control characteristics are stabilized by suppressing the inclination of the plunger due to vibration during operation, the plunger operating stably, and the sliding resistance of the plunger being reduced (for example, Patent Documents) 3).

The plate spring is not fixedly connected to the connecting body of the plunger and the valve body, and the structure is such that the plate spring simply contacts and engages the flange end surface of the connecting body, thereby fixing the connecting body and the plate spring. There is one in which variations (assembly errors) are prevented from occurring in the state so that the flow rate control characteristics do not vary from individual to individual (for example, Patent Document 4).
JP 2002-71045 A JP 2002-357280 A JP 2004-60622 A JP 2005-147315 A

  However, in any of the conventional ones, the plunger comes into contact with the inner peripheral surface of the plunger tube, so that sliding resistance occurs during operation. For this reason, hysteresis occurs in the flow rate control characteristic, the output flow rate is not stable, and there is a limit to stable and highly accurate flow control of a small amount. Also, oscillation occurs due to sliding resistance during operation, and this also causes the output flow rate to be unstable.

  The problem to be solved by the present invention is that, in an electromagnetic proportional valve, a sliding resistance is avoided when the plunger comes into contact with the inner peripheral surface of the plunger tube, and there is no variation in flow rate control characteristics, and stable high accuracy It is to perform a very small amount of flow control.

An electromagnetic proportional valve according to the present invention includes a valve housing having a valve chamber and a valve port, and a linear plunger that is provided in a cylindrical plunger tube attached to the valve housing so as to be movable in the axial direction. An electromagnetic actuator, a valve body provided in the valve chamber and connected to the plunger, the opening degree of the valve port being changed by movement in an axial direction, a connection body of the plunger and the valve body, and the valve housing An electromagnetic proportional valve that controls the flow rate by determining the axial movement position of the valve body by an equilibrium relationship between the electromagnetic force generated by the electromagnetic actuator and the spring force of the leaf spring. in the plate spring, with an annular, it engages loosely circumferentially of the outer periphery of the connecting member at the inner periphery side, between the inner and outer circumferential edges of the ring portion, an outer peripheral edge A plurality of slits are formed in a form in which a predetermined radial width is left on each of the inner peripheral edge side and the slit has a predetermined circumferential width and a predetermined radial length. Jo the equally spaced, in a predetermined radial width range of the outer peripheral edge and inner peripheral edge side, has a continuous surface in the circumferential direction without including the portion of the slit, with the continuous surface of the outer peripheral edge , engaged along the end face of the annular formed in the valve housing, with the continuous surface of the inner peripheral edge side, engaged along the end face of the annular shape formed in the coupling body, the plunger tube The radial clearance A is provided between the plunger tube and the plunger due to the difference between the inner diameter of the plunger and the outer diameter of the plunger, and the outer diameter of the coupling body and the leaf spring at the portion where the leaf spring is loosely fitted Depending on the difference between the inner diameter of A radial clearance B is provided between the connecting body and the leaf spring, and a difference between an inner diameter of the circumferential valve housing and an outer diameter of the leaf spring at a portion where the leaf spring abuts and engages. A radial clearance C is provided between the valve housing and the leaf spring, and the radial clearance A, the radial clearance B, and the radial clearance C are set so as to satisfy the condition A> (B + C). Has been.

  In the electromagnetic proportional valve according to the present invention, preferably, the ratio H: Db between the axial length H of the plunger and the outer diameter Db of the plunger is 1: 1 to 3: 1.

  In the electromagnetic proportional valve according to the present invention, preferably, the leaf spring is provided as a valve closing spring that urges the connecting body in a valve closing direction, and the end surface of the connecting body and the valve housing are in a maximum valve closed state. Is preliminarily deformed in a conical shape due to a deviation in the axial position relative to the end surface, and a preload is applied by the conical elastic deformation, so that the plate surface is the end surface of the coupling body and the valve housing. Abutting and engaging with these end faces in a state inclined with respect to the end faces.

  In the electromagnetic proportional valve according to the present invention, the leaf spring is not fixedly connected to the connection body between the plunger and the valve body, but only abuts and engages with the flange end surface of the connection body. Variation (assembly error) does not occur.

  With this mounting structure, the plunger moves freely in the radial direction with respect to the plunger tube, but the radial clearance A, radial clearance B, and radial clearance C are set so as to satisfy the condition of A> (B + C). Therefore, even if the plunger moves in the radial direction to the maximum (B + C) with respect to the plunger tube, the plunger does not contact the inner peripheral surface of the plunger tube. As a result, there is no sliding resistance during operation, no hysteresis occurs in the flow rate control characteristics, and the output flow rate is stabilized.

  One embodiment of an electromagnetic proportional valve according to the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the electromagnetic proportional valve has a valve housing 11. The valve housing 11 is constituted by an assembly of a housing main body 12 and a lid member 14 fixed to the housing main body 12 by a screw portion 13. The housing body 12 and the lid member 14 define a valve chamber 16 that is hermetically sealed by an O-ring 15A. A cylindrical filter member 17 made of a porous material or the like is disposed in the valve chamber 16 via an O-ring 15B.

  A first input / output port 18 and a second input / output port 19 are formed in the housing body 12. A cylindrical valve seat member 20 is fixed to the housing body 12 concentrically with the filter member 17. The valve seat member 20 communicates with the second inlet / outlet port 19 through an internal passage (inner cylinder portion) 21, has a valve port 22 concentric with the filter member 17 at the upper portion, and the upper surface becomes the valve seat surface 23. ing. The first inlet / outlet port 18 communicates directly with the valve chamber 16.

  A linear electromagnetic actuator 31 is attached to the upper portion of the valve housing 11. The electromagnetic actuator 31 has a cylindrical plunger tube 32 fixed to the lid member 14 by brazing. The plunger tube 32 is fitted on and inserted into a central through hole 24 formed in the lid member 14 at the lower end side, and is arranged on the concentric shaft with the filter member 17. In FIG. 1, reference numeral 25 indicates a brazed portion of the plunger tube 32.

  A suction element 33 that also serves as a plug is fitted and fixed to the upper end side of the plunger tube 32. On the outside of the plunger tube 32, an electromagnetic coil member 37 including an outer rod 34, a bobbin 35, a winding 36 and the like is fixedly attached by a retaining ring 38.

  A cylindrical plunger 39 is provided in the plunger tube 32 so as to be movable in the axial direction (valve opening / closing direction). A holder receiving hole 40 is formed on the lower end of the plunger 39 on the concentric shaft with the filter member 17, and a cylindrical holder member 41 is fitted and fixed on the concentric shaft with the filter member 17 in the holder receiving hole 40. Has been.

  As shown in FIG. 2, the holder member 41 has an annular inner peripheral flange 42 and an annular outer peripheral flange 43 at the lower end, and an inner (inner cylinder portion) 41 </ b> A. The valve body 44 and the stem member 45 are accommodated.

  The valve body 44 is prevented from coming off by engagement with the inner peripheral flange 42, and is connected to the plunger 39 via the holder member 41. The valve body 44 is opposed to the valve seat surface 23 with a lower bottom surface 46, and performs opening / closing and opening adjustment of the valve port 22 by movement in the axial direction (vertical direction).

  In this embodiment, the plunger 39, the holder member 41, the valve body 44, and the stem member 45 form one connecting body.

  On the lower bottom surface side of the lid member 14, a circular large-diameter portion 26 for accommodating a leaf spring is formed on the concentric shaft with the filter member 17. An annular leaf spring 51 is disposed in the large diameter portion 26. The leaf spring 51 is loosely fitted to the circumferential outer periphery 41B of the holder member 41 with a circular center opening 51A (see FIG. 5), and the lower bottom surface of the large-diameter portion 26 is on the upper surface on the outer peripheral edge 52 side. A downward annular end surface (end surface on the valve housing 11 side) 27 formed and abuts and engages, and an upward annular end surface (end surface on the coupling body side) formed by the upper surface of the outer peripheral flange 43 on the lower surface on the inner peripheral edge 53 side. ) 47 and urges the valve body 44 in the valve closing direction. As a result, the leaf spring 51 forms a valve closing spring.

  Since the leaf spring 51 is merely abutted and engaged with the end faces 27 and 47 and is not fastened and fixed to the valve housing 11 side, the valve body 44 side, or the plunger 32 side, the leaf spring 51 is fixed. There is no variation (assembly error) in the state.

  As shown in FIG. 1, the electromagnetic actuator 31 is energized by energizing the electromagnetic coil member 37, and a magnetic attraction force (electromagnetic force) corresponding to a coil current value controlled by duty ratio control or the like. ) Is generated in the suction force 33, and the coupling body of the holder member 41 including the valve body 44 and the plunger 39 is driven upward, that is, in the valve opening direction.

  As a result, the axial position of the valve body 44 is determined by the balanced relationship between the electromagnetic force generated by the electromagnetic actuator 31 and the spring force of the leaf spring 51, and flow rate control proportional to the current supplied to the electromagnetic actuator 31 is performed.

  As shown in FIG. 2, in the above-described configuration, the leaf spring 51 merely contacts and engages the end surfaces 27 and 47, and either the valve body 44 side or the plunger 32 side is present on the valve housing 11 side. In addition, the coupling body constituted by the plunger 39, the holder member 41, the valve body 44 and the stem member 45 is freely movable in the radial direction with respect to the plunger tube 32.

  A radial clearance A is provided between the plunger tube 32 and the plunger 39 by the difference between the inner diameter Da of the plunger tube 32 and the outer diameter Db of the plunger 39, and the outer portion of the holder member 41 where the leaf spring 51 is loosely fitted. A radial clearance B is provided between the holder member 41 and the leaf spring 51 by the difference between the diameter (diameter of the inner peripheral edge of the end face 47) Dc and the inner diameter Dd of the leaf spring 51, and the leaf spring 51 is in contact with and engaged. A radial clearance C is provided between the valve housing 11 and the leaf spring 51 by the difference between the inner diameter (diameter of the outer peripheral edge of the end surface 27) Df of the circumferential cover member 14 and the outer diameter De of the leaf spring 51. It is done.

  In this embodiment, the radial clearance A, the radial clearance B, and the radial clearance C are set so as to satisfy the condition of A> (B + C).

  The maximum amount of movement of the plunger 39 in the radial direction relative to the plunger tube 32 is (B + C), and A> (B + C). The plunger 39 does not contact the inner peripheral surface of the plunger tube 32.

  As a result, there is no sliding resistance during operation, no hysteresis occurs in the flow rate control characteristics, and the output flow rate is stabilized.

  When an evaluation test on the ratio between the inner diameter Da of the plunger tube 32 and the outer diameter Db of the plunger 39 of the electromagnetic proportional valve having the above-described configuration was performed, an evaluation result was obtained as shown in FIG. In this evaluation test, feedback flow rate control with a constant primary pressure, a control flow rate of 1200 ± 0.25 ml / min, and a sampling rate of 18 seconds is performed within a test time of 440 seconds. Evaluation was carried out with the time (stable time) for maintaining within 0.25 ml / min).

  Thereby, in the electromagnetic proportional valve having the above-described configuration, the ratio Da: Db between the inner diameter Da of the plunger tube 32 and the outer diameter Db of the plunger 39 is 1.01: 1 to 1.3: 1, preferably, a stable time. It was found that 1.08: 1 to 1.22: 1, which can obtain about 180 seconds or more, is preferable.

  Further, when an equivalent evaluation test was performed on the ratio H: Db (aspect ratio) between the axial length H of the plunger 39 (see FIG. 1) and the outer diameter Db of the plunger 39, as shown in FIG. Evaluation results were obtained.

  As a result, the ratio H: Db (aspect ratio) between the axial length H of the plunger 39 and the outer diameter Db of the plunger 39 is 1: 1 to 3: 1, preferably, a stabilization time of about 180 seconds or more is obtained. It turned out that it is good to set to 5: 1-2.5: 1.

  By setting such a ratio, the moment acting on the plunger 39 due to vibration is reduced, the inclination of the plunger 39 due to vibration during operation is suppressed, and coupled with the fact that the plunger 39 does not contact the inner peripheral surface of the plunger tube 32. The plunger 39 operates stably and the flow rate control characteristic is stabilized.

  As shown in FIG. 5, the leaf spring 51 is an annular plate having a circular center opening 51A, is made of a metal material having spring properties, and is used for adjusting the spring constant. A plurality of ring-shaped portions 51B between the peripheral edge 52 and the inner peripheral edge 53 are provided with predetermined radial widths Wa and Wb on the outer peripheral edge 52 side and the inner peripheral edge 53 side. The slits 54 are radially arranged at equal intervals. Thereby, the leaf | plate spring 51 has the annular belt-like continuous surfaces 51D and 51E by radial direction width Wa and Wb which continued in the circumferential direction at each of the outer periphery 52 side and the inner periphery 53 side.

  The inside diameter of the leaf spring 51 is Dd, the outside diameter of the leaf spring 51 is De, the diameter of the inner envelope circle connecting the inner ends of the plurality of slits 54 is Di, and the outside connecting the outer ends of the plurality of slits 54 When the diameter of the envelope circle is Dj, the radial length L of the slit 54 is (Dj−Di) / 2, which is smaller than the radial dimension (De−Dd) / 2 of the annular portion 51B. The radial width Wa of the continuous surface 51D on the outer peripheral edge 52 side is (De−Dj) / 2, and the radial width Wb of the continuous surface 51E on the inner peripheral edge 53 side is (Di−Dd) / 2.

When the outer diameter of the outer peripheral flange 43 (the diameter of the outer peripheral edge of the end face 47) is Dg and the diameter of the inner peripheral edge of the end face 27 of the lid member 14 is Dh, the inner envelope circle diameter Di and the outer envelope circle diameter Dj. Is set to satisfy the following conditions.
Di> (Dg + B + C)
Dj <(Dh-B-C)

  Accordingly, the leaf spring 51 does not include the slit 54 within the predetermined radial width (Wa) range on the outer peripheral edge 52 side, and always includes the end surface 27 ( 2) and within the predetermined radial width (Wb) range on the inner peripheral edge 53 side, the outer peripheral flange 43 is always provided with an annular belt-like continuous surface 51E without including the slit 54 portion. The end face 47 (see FIG. 2) is abutted and engaged.

  As a result, the connecting body of the plunger 39, the holder member 41, and the valve body 44 is inclined with respect to the central axis of the plunger tube 32, and the leaf spring 51 is against the end surface 27 of the lid member 14 and the end surface 47 of the outer peripheral flange 43. Even if it is in a state where it comes into contact with each other, the contact state is always performed on the continuous surface 52 in the form of an annular band, and it is unpredictable whether it is a piece containing a slit 54 or a piece containing no slit 54. It is not performed in such a state.

  As a result, an unstable element of the spring force of the leaf spring 51 acting on the valve body 44 is eliminated, and the spring force of the leaf spring 51 acting on the valve body 44 does not vary even if one-side contact occurs. This is because the spring force of the leaf spring 51 acting on the valve element 44 varies depending on whether it is a single piece including the slit 54 or a single piece that does not include the slit 54. By contacting and engaging the end surfaces 27 and 47 with the continuous surfaces 51D and 51E, this means that this is not the case.

  6A shows a state in which a preload is not applied to the leaf spring 51, FIG. 6B shows a state in which a preload is applied to the leaf spring 51 in the maximum valve closed state, and FIG. 6C shows a state in which the maximum valve is opened. Each state is shown.

  As shown in FIG. 6B, in the maximum valve closed state (the state in which the valve body 44 is in contact with the valve seat surface 23), the leaf spring 51 includes the end surface 27 of the lid member 14 and the outer peripheral flange. Due to the deviation of the axial position relative to the end face 47 of 43, a preload is applied by elastic deformation in a conical shape.

  The relative axial displacement between the end surface 27 of the lid member 14 and the end surface 47 of the outer peripheral flange 43 is the amount by which the lid member 14 is screwed into the valve housing body 12 by the screw portion 13 shown in FIG. Can be adjusted to the required value.

  Due to this conical elastic deformation, the leaf spring 51 is provided with reference signs A and B on the end surfaces 27 and 47 in a state where the plate surface is inclined with respect to the end surface 27 of the lid member 14 and the end surface 47 of the outer peripheral flange 43. As shown, it abuts by line contact. In operation, as shown in FIG. 6C, the leaf spring 51 is further bent, and the line contact position with respect to the end surfaces 27 and 47 of the leaf spring 51 is changed, so that sliding resistance due to surface contact is generated. There is no.

  This also eliminates the occurrence of hysteresis in the flow rate control characteristic and stabilizes the output flow rate.

  In this case, the corners of the end surface 27 of the lid member 14 and the end surface 47 of the outer peripheral flange 43 may be chamfered or rounded.

A reference example of the leaf spring is shown in FIG. As shown in FIG. 7A, a wide slit 56 is formed, as shown in FIG. 7B, a slit 57 is formed in the circumferential direction, and FIG. As shown in FIG. 7C, there are a case where a slit 58 is formed in a crescent shape, a case where a slit is not formed as shown in FIG.

  In any case, the leaf spring 51 only needs to be in contact with the end surface 27 of the lid member 14 and the end surface 47 of the outer peripheral flange 43 with a continuous surface.

It is a longitudinal cross-sectional view which shows one Embodiment of the electromagnetic proportional valve by this invention. It is a longitudinal cross-sectional view which expands and shows the principal part of one Embodiment of the electromagnetic proportional valve by this invention. It is a graph which shows the evaluation test result regarding the ratio of the plunger tube inner diameter of the electromagnetic proportional valve by one embodiment, and a plunger outer diameter. It is a graph which shows the evaluation test result regarding the aspect ratio of the plunger of the electromagnetic proportional valve by one embodiment. It is an enlarged plan view of the leaf | plate spring used with the electromagnetic proportional valve by one Embodiment. (A)-(c) is an expanded sectional view of the leaf | plate spring attachment part of the electromagnetic proportional valve by one Embodiment. (A) ~ (d) is a plan view showing a reference example of the leaf springs used in the electrodeposition磁比example valve.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Valve housing 16 Valve chamber 22 Valve port 27 End surface 31 Electromagnetic actuator 32 Plunger tube 39 Plunger 44 Valve body 47 End surface 51 Leaf spring 51D, 51E Continuous surface 54 Slit

Claims (3)

A valve housing having a valve chamber and a valve port;
A linear electromagnetic actuator including a columnar plunger movably provided in an axial direction in a cylindrical plunger tube attached to the valve housing;
A valve body that is provided in the valve chamber and connected to the plunger, and changes an opening degree of the valve port by axial movement;
A leaf spring built in between the plunger and the connecting body of the valve body and the valve housing;
In the electromagnetic proportional valve for controlling the flow rate, the axial movement position of the valve body is determined by the equilibrium relationship between the electromagnetic force generated by the electromagnetic actuator and the spring force of the leaf spring.
The leaf spring is annular, loosely fitted to the outer periphery of the coupling body on the inner periphery side, and between the outer periphery and the inner periphery of the annular portion, on the outer periphery side and the inner periphery side. A plurality of slits are formed so as to leave a predetermined radial width in each of the slits, and the slits have a predetermined circumferential width and a predetermined radial length and are radially spaced at equal intervals. The valve housing has a continuous surface in the circumferential direction without including the slit portion within a predetermined radial width range on the outer peripheral edge side and the inner peripheral edge side, and has the continuous surface on the outer peripheral edge side in the valve housing. Abutting engagement with the formed annular end surface, with the continuous surface on the inner peripheral edge side, abutting engagement with the annular end surface formed on the coupling body,
A radial clearance A is provided between the plunger tube and the plunger due to the difference between the inner diameter of the plunger tube and the outer diameter of the plunger,
A radial clearance B is provided between the connecting body and the leaf spring due to a difference between an outer diameter of the connecting body and an inner diameter of the leaf spring at a portion where the leaf spring is loosely fitted,
A radial clearance C is provided between the valve housing and the leaf spring due to a difference between an inner diameter of the circumferential valve housing and an outer diameter of the leaf spring at a portion where the leaf spring abuts and engages.
An electromagnetic proportional valve in which the radial clearance A, the radial clearance B, and the radial clearance C are set so as to satisfy a condition of A> (B + C).   2. The proportional solenoid valve according to claim 1, wherein a ratio H: Db of an axial length H of the plunger to an outer diameter Db of the plunger is 1: 1 to 3: 1. The leaf spring is provided as a valve closing spring that biases the connecting body in a valve closing direction, and in a maximum valve closed state, a relative axial position between the end face of the connecting body and the end face of the valve housing is provided. These end surfaces are elastically deformed into a conical shape due to the bias of the pre-load, and the plate surfaces are inclined with respect to the end surface of the coupling body and the end surface of the valve housing by the conical elastic deformation. The electromagnetic proportional valve according to claim 1, which is in contact with and engaged with the electromagnetic proportional valve.

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