Solenoid pump

Abstract

The present invention provides a solenoid pump that prevents the diaphragm valve from separating from the input-side valve seat as much as possible, even when the pressure at the input port rises, and that does not pose a risk of interference when filling the fluid upstream of the input port. [Solution] The body 12 of the solenoid pump 10 includes an input valve seat 22 and an output valve seat 24, and the movable part 38 includes a diaphragm valve 40 and a movable iron core 44. The diaphragm valve is in contact with the input valve seat and the output valve seat, a pump chamber is formed between the diaphragm valve and the body, and the input valve seat is formed in a position closer to the diaphragm valve than the output valve seat.

Description

Technical Field

[0001] The present invention relates to a solenoid pump having a movable portion that is displaced by the excitation action of a solenoid, wherein the opening and closing of a fluid passage is switched by the displacement of the movable portion. Background Art

[0002] Conventionally, in the chemical field or the medical field, a liquid supply device that supplies a trace amount of liquid has been used. This liquid supply device is provided with a solenoid pump that allows a trace amount of liquid to flow in and out in a flow path, and is controlled to supply a predetermined amount of liquid.

[0003] For example, Japanese Patent Laid-Open No. 2012-92777 describes a solenoid pump comprising: a housing having a fluid passage formed therein that communicates an input port and an output port; and a movable member that opens and closes the fluid passage in accordance with the excitation state of a solenoid. The fluid passage includes an input side passage provided with a check valve, an output side passage provided with a check valve, and a pump chamber communicating with the input side passage and the output side passage, and the pump chamber is surrounded by the movable member and the housing. Prior Art Documents Patent Documents

[0004] Patent Document 1 Japanese Patent Laid-Open No. 2012-92777 Summary of the Invention Problems to be Solved by the Invention

[0005] By the way, there are cases where it is desired to fill liquid on the upstream side of the input port of the solenoid pump using a pump other than the solenoid pump. In such cases, the pressure at the input port increases, so there is a risk that the movable portion of the solenoid pump will be displaced from the valve-closed state during liquid filling.

[0006] To prevent the movable part of the solenoid pump from being displaced even when the pressure at the input port rises, one could consider increasing the spring constant of the spring that biases the movable part in the direction of closing the fluid passage when the solenoid is not energized. However, increasing the spring constant of the spring that biases the movable part would increase the excitation power of the solenoid required to displace the movable part against the biasing force of the spring, and there is also a risk that the solenoid will overheat and fail.

[0007] The present invention aims to solve the problems described above. [Means for solving the problem]

[0008] The present invention relates to a solenoid pump comprising a body, a movable part, and an excitation coil, wherein the body comprises an input port, an output port, an input valve seat, and an output valve seat, and the movable part comprises a diaphragm valve and a movable iron core. The diaphragm valve is capable of contacting the input valve seat and the output valve seat, a pump chamber is formed between the diaphragm valve and the body, and when the diaphragm valve is not in contact with the input valve seat and the output valve seat, the input valve seat is closer to the diaphragm valve than the output valve seat. [Effects of the Invention]

[0009] According to the solenoid pump of the present invention, the input valve seat is formed in a position closer to the diaphragm valve than the output valve seat. Therefore, when the valve changes from an open state to a closed state, the diaphragm valve contacts the input valve seat before the output valve seat, ensuring that the fluid in the pump chamber and its residual pressure are reliably released from the output port. As a result, even if the pressure at the input port rises, the diaphragm valve is prevented from separating from the input valve seat as much as possible, and there is no risk of problems occurring even if fluid is filled upstream of the input port. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a cross-sectional view of a solenoid pump according to an embodiment of the present invention. [Figure 2]Figure 2 is a magnified view of a portion of the solenoid pump shown in Figure 1. [Figure 3] Figure 3 is a cross-sectional view of the solenoid pump shown in Figure 1 when the excitation coil is energized. [Modes for carrying out the invention]

[0011] As shown in Figure 1, the solenoid pump 10 according to an embodiment of the present invention includes a first body 12, a second body 30, a housing 32, a movable part 38, an excitation coil 54, and an adjustment screw 50. In the following description, when terms relating to the up, down, left, and right directions are used, they refer to the directions shown in the drawings for convenience and do not limit the actual arrangement of the components.

[0012] The first body 12 includes an input port 14 opening on the right side of the first body 12, an output port 16 opening on the left side of the first body 12, an input-side passage 18 communicating with the input port 14, and an output-side passage 20 communicating with the output port 16. The input port 14 is connected to a fluid storage source, such as a tank, via piping (not shown). The output port 16 is connected to a target container, such as a fluid mixing vessel, via piping (not shown).

[0013] The first body 12 has a circular recess 12a opening on the upper surface of the first body 12 and an annular groove 12b that is excavated downward on the outer circumference of the recess 12a. The input-side passage 18 opens on the bottom surface of the recess 12a, and the first body 12 includes an input-side valve seat 22 formed around the opening. The output-side passage 20 opens on the bottom surface of the recess 12a, and the first body 12 includes an output-side valve seat 24 formed around the opening. As shown in Figure 2, the input-side valve seat 22 is located above the output-side valve seat 24 by a height H.

[0014] The second body 30 is positioned above the first body 12 and is fixed to the first body 12 by fastening means such as bolts. A hole 30a is formed in the center of the second body 30, penetrating it vertically. The lower part of the second body 30 has an annular projection 30b that protrudes downward. The housing 32 is positioned above the second body 30 and is fixed to the second body 30 by fastening means such as bolts.

[0015] A sleeve 34 and a fixed core 36 are positioned inside the housing 32. The sleeve 34 is configured as a bottomed cylindrical shape opening downwards and fits into the lower part of the housing 32. The sleeve 34 has a flange 34c that widens outward from its lower end. The flange 34c is sandwiched between the upper surface of the second body 30 and the lower surface of the housing 32. This positions and fixes the sleeve 34 relative to the second body 30 and the housing 32. A hole 34a is formed in the center of the bottom of the sleeve 34. The fixed core 36 is positioned between the outer bottom surface of the sleeve 34 and the upper inner surface of the housing 32. A vertically penetrating screw hole 36a is formed in the center of the fixed core 36.

[0016] The movable part 38 includes a diaphragm valve 40, a support 42, and a movable iron core 44. The diaphragm valve 40 is made of a rubber material and has a predetermined elasticity. As shown in Figure 2, the diaphragm valve 40 has a body portion 40a and a diaphragm portion 40c that is curved and deformable, extending from the outer circumference of the body portion 40a. The body portion 40a has a hollow portion that receives the lower part of the support 42. The bottom surface 40b of the body portion 40a is a uniform circular plane and is capable of contacting the input valve seat 22 and the output valve seat 24. The support 42 is integrally connected to the body portion 40a by the lower part of the support 42 being enclosed within the body portion 40a.

[0017] In a state where the diaphragm valve 40 is not in contact with the input-side valve seat 22 and the output-side valve seat 24, the input-side valve seat 22 is closer to the diaphragm valve 40 than the output-side valve seat 24 by said height H. That is, in FIG. 3, the distance from the input-side valve seat 22 to the bottom surface 40b of the diaphragm valve 40 is shorter by said height H than the distance from the output-side valve seat 24 to the bottom surface 40b of the diaphragm valve 40.

[0018] The outer peripheral portion of the diaphragm portion 40c has an annular convex portion 40d protruding downward. The convex portion 40d of the diaphragm portion 40c engages with the groove portion 12b of the first body 12, and the upper surface of the outer peripheral portion of the diaphragm portion 40c abuts against the convex portion 30b of the second body 30. Thereby, the diaphragm portion 40c is positioned and fixed with respect to the first body 12 and the second body 30. A pump chamber 46 is formed between the diaphragm valve 40 and the first body 12. The pump chamber 46 is a space defined by the lower surface of the diaphragm portion 40c, the surface of the recess 12a of the first body 12, and the like.

[0019] The movable iron core 44 is formed in a columnar shape. The movable iron core 44 is fitted inside the sleeve 34 and guided so as to be displaceable in the axial direction X (vertical direction) of the sleeve 34. The movable iron core 44 is connected to the support body 42 by a male screw formed on the upper part of the support body 42 being screwed into a female screw formed on the lower part of the movable iron core 44. The main body portion 40a of the diaphragm valve 40, the support body 42, and the movable iron core 44 are displaced integrally in the vertical direction. The input-side valve seat 22 and the output-side valve seat 24 are located in opposite directions across the axis X of the sleeve 34.

[0020] As the movable portion 38 is displaced in the vertical direction, the diaphragm portion 40c is curved and deformed, and the volume of the pump chamber 46 changes. When the movable portion 38 is displaced upward, the volume of the pump chamber 46 increases, and when the movable portion 38 is displaced downward, the volume of the pump chamber 46 decreases. The movable portion 38 is urged downward by the urging force of a spring 48 disposed between a step portion 44a formed on the outer periphery of the movable iron core 44 and the bottom surface (inner surface of the bottom portion) 34b of the sleeve 34.

[0021] The excitation coil 54 is disposed inside the housing 32 and surrounds the sleeve 34 and the fixed iron core 36. When the excitation coil 54 is energized, the magnetic force acting among the excitation coil 54, the fixed iron core 36 and the movable iron core 44 displaces the movable portion 38 upward against the biasing force of the spring 48. When the excitation coil 54 is not energized, the main body portion 40a of the diaphragm valve 40 is brought into contact with the input side valve seat 22 and the output side valve seat 24 by the biasing force of the spring 48. The diaphragm valve 40 is a normally closed valve.

[0022] The adjustment screw 50 is screwed into the screw hole 36a of the fixed iron core 36. The upper end of the adjustment screw 50 protrudes upward from the housing 32, and a nut 52 is attached to the protruding portion. The lower end of the adjustment screw 50 passes through the hole 34a of the sleeve 34 and protrudes downward from the bottom surface 34b of the sleeve 34. When the excitation coil 54 is not energized, the lower end of the adjustment screw 50 faces the upper end of the movable iron core 44 with a predetermined gap S therebetween. The upward displacement of the movable iron core 44 is restricted when the movable iron core 44 abuts against the lower end of the adjustment screw 50 (see FIG. 3).

[0023] By changing the screwing position of the adjustment screw 50 relative to the fixed iron core 36, the vertical displacement amount (stroke) of the movable portion 38 can be adjusted. When the lower end of the adjustment screw 50 does not protrude from the bottom surface 34b of the sleeve 34, the stroke of the movable portion 38 becomes maximum. As the length by which the lower end of the adjustment screw 50 protrudes from the bottom surface 34b of the sleeve 34 increases, the gap S decreases, and the stroke of the movable portion 38 decreases.

[0024] The state when the diaphragm valve 40 is in contact with the input side valve seat 22 and the output side valve seat 24 will be described. Since the input side valve seat 22 is formed at a position closer to the diaphragm valve 40 than the output side valve seat 24, the compression amount of the main body portion 40a of the diaphragm valve 40 is large in the vicinity of the input side valve seat 22, and is small in the vicinity of the output side valve seat 24.

[0025] An input-side check valve 26 is positioned in the middle of the input-side passage 18, and an output-side check valve 28 is positioned in the middle of the output-side passage 20. The input-side check valve 26 allows fluid flow from the input port 14 toward the pump chamber 46 and blocks fluid flow from the pump chamber 46 toward the input port 14. The output-side check valve 28 allows fluid flow from the pump chamber 46 toward the output port 16 and blocks fluid flow from the output port 16 toward the pump chamber 46.

[0026] Next, the basic operation of the solenoid pump 10 will be described. In the initial state, the excitation coil 54 is not energized, and the diaphragm valve 40 is in contact with the input valve seat 22 and the output valve seat 24 due to the biasing force of the spring 48 (see Figure 1). Also, the lower end of the adjustment screw 50 faces the upper end of the movable iron core 44, separated by a predetermined gap S.

[0027] When the excitation coil 54 is energized from the initial state, the movable part 38 is displaced upward, and the volume of the pump chamber 46 increases. As a result, fluid is drawn in through the input port 14. The drawn-in fluid flows into the pump chamber 46 through the input-side passage 18, which is interposed by the input-side check valve 26. As shown in Figure 3, when the movable core 44 comes into contact with the adjustment screw 50, the displacement of the movable part 38 stops, and the increase in the volume of the pump chamber 46 also stops. The volume of the pump chamber 46 increases by an amount corresponding to the stroke of the movable part 38, and an amount of fluid corresponding to the increase in the volume of the pump chamber 46 is stored in the pump chamber 46. Note that due to the action of the output-side check valve 28, no fluid flows from the output port 16 towards the pump chamber 46.

[0028] Subsequently, when the excitation coil 54 is de-energized, the movable part 38 is displaced downward, and the volume of the pump chamber 46 decreases. As a result, the fluid stored in the pump chamber 46 is discharged from the output port 16 through the output-side passage 20, which is interposed by the output-side check valve 28. The diaphragm valve 40 contacts the input-side valve seat 22 and the output-side valve seat 24, returning to its initial state. Due to the action of the input-side check valve 26, the fluid stored in the pump chamber 46 does not flow back toward the input port 14.

[0029] Each time the excitation coil 54 is energized and de-energized, an amount of fluid corresponding to the stroke of the movable part 38 is drawn in from the input port 14 and discharged from the output port 16. The larger the gap S and the larger the stroke of the movable part 38, the greater the amount of fluid drawn in from the input port 14 and discharged from the output port 16. The energization and de-energization of the excitation coil 54 is repeated as many times as necessary.

[0030] Next, consider the case where the pressure in the input port 14 rises due to operations such as filling the input port 14 with fluid upstream of the input port 14. When the pressure in the input port 14 rises, the pressure in the input-side passage 18 also rises. This increased pressure acts on the bottom surface 40b of the diaphragm valve 40, and the movable part 38, including the diaphragm valve 40, is biased upward. However, since the input-side valve seat 22 is formed in a position closer to the diaphragm valve 40 than the output-side valve seat 24, a gap is unlikely to form between the diaphragm valve 40 and the input-side valve seat 22.

[0031] Although it has been verified in prototypes that the diaphragm valve 40 does not easily separate from the input valve seat 22 even when the pressure in the input passage 18 increases, the reason for this will be discussed below.

[0032] When the excitation coil 54 is not energized, the forces acting on the movable part 38 include a downward force from the spring 48, an upward force from the input valve seat 22, an upward force from the fluid in the pump chamber 46, and an upward force due to the pressure in the input passage 18. Hereinafter, these forces will be referred to as the "first force," "second force," "third force," and "fourth force," respectively. Furthermore, the state in which the diaphragm valve 40 is not in contact with the input valve seat 22 and the output valve seat 24 is called the "valve open state," and the state in which the diaphragm valve 40 is in contact with the input valve seat 22 and the output valve seat 24 is called the "valve closed state."

[0033] Since the input valve seat 22 is formed closer to the diaphragm valve 40 than the output valve seat 24, when the movable part 38 is displaced downward and the valve changes from the open state to the closed state, the contact of the diaphragm valve 40 with the output valve seat 24 occurs later than the contact of the diaphragm valve 40 with the input valve seat 22. This timing difference ensures that the fluid in the pump chamber 46 and its residual pressure are reliably released from the output port 16. In other words, the third force is kept as small as possible. If the sum of the second to fourth forces opposing the first force exceeds a predetermined value, the valve may transition from the closed state to the open state, but since the third force is kept small, there is enough margin to maintain the closed state even if the fourth force increases. For this reason, it is difficult for the valve to transition from the closed state to the open state even if the fourth force increases.

[0034] According to this embodiment, since the input valve seat 22 is formed in a position closer to the diaphragm valve 40 than the output valve seat 24, when the valve changes from an open state to a closed state, the fluid in the pump chamber 46 and its residual pressure can be reliably released from the output port 16. For this reason, even if the pressure in the input port 14 rises, the diaphragm valve 40 is prevented from moving away from the input valve seat 22 as much as possible, and there is no risk of problems occurring even if fluid is filled on the upstream side of the input port 14.

[0035] The present invention is not limited to the disclosure described above, and can adopt various configurations without departing from the spirit of the invention. [Explanation of Symbols]

[0036] 10...Solenoid pump 12...First body (body) 14…Input port 16…Output port 18...Input side passage 20...Output side passage 22...Input valve seat 24...Output valve seat 26...Input side check valve 28...Output side check valve 30...Second body (body) 34...Sleeve 34a…hole 34b…bottom 36...Fixed core 38...Movable part 40...Diaphragm valve 44...Movable core 44a...Step section 46...Pump room 48...Spring 50...Adjustment screw 54…Excitation coil

Claims

1. A solenoid pump comprising a body, a movable part, and an excitation coil, The body comprises an input port, an output port, an input valve seat, and an output valve seat, the movable part includes a diaphragm valve and a movable core, the diaphragm valve is capable of contacting the input valve seat and the output valve seat, a pump chamber is formed between the diaphragm valve and the body, and when the diaphragm valve is not in contact with the input valve seat and the output valve seat, the input valve seat is closer to the diaphragm valve than the output valve seat is closer to the diaphragm valve, in a solenoid pump.

2. In the solenoid pump according to claim 1, The body is a solenoid pump comprising an input-side passage interposed with an input-side check valve and an output-side passage interposed with an output-side check valve.

3. In the solenoid pump according to claim 1, A solenoid pump in which a housing is fixed to the body, a cylindrical sleeve is placed inside the housing, a cylindrical movable core is fitted into the sleeve, and the movable core is guided to be displaceable in the axial direction of the sleeve.

4. In the solenoid pump according to claim 3, The sleeve is configured as a bottomed cylindrical shape, and a spring is positioned between the stepped portion formed on the movable iron core and the bottom surface of the sleeve in this solenoid pump.

5. In the solenoid pump according to claim 3, A solenoid pump comprising a fixed iron core disposed inside the housing and an adjustment screw screwed into the fixed iron core, wherein one end of the adjustment screw protrudes outward from the housing and the other end of the adjustment screw faces the movable iron core with a predetermined gap between them.

6. In the solenoid pump according to claim 5, The excitation coil is a solenoid pump surrounding the sleeve and the fixed iron core.

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