CN210483979U

CN210483979U - Electromagnetic pump

Info

Publication number: CN210483979U
Application number: CN201921475171.4U
Authority: CN
Inventors: 薮下聪; 田中良幸; 三瓶隆行
Original assignee: Nidec Tosok Corp
Current assignee: Nidec Powertrain Systems Corp
Priority date: 2018-09-10
Filing date: 2019-09-05
Publication date: 2020-05-08
Anticipated expiration: 2029-09-05
Also published as: JP2020041469A

Abstract

The utility model provides an electromagnetic pump (1), thereby can omit the process of being fixed in cylinder body (51) with 2 nd check valve (80) in the equipment process and simplify the equipment process. The 2 nd check valve (80) is movable in the axial direction (Z-axis direction) within the flow path (54), a 3 rd elastic body (90) that urges the 2 nd check valve (80) and the piston (60) in the axial direction in the opposite direction is disposed between the 2 nd check valve (80) and the piston (60) in the axial direction of the flow path (54), and the 2 nd check valve (80) is urged by the 3 rd elastic body (90) toward a surface of the inner wall surface of the cylinder (51) that faces a wall (81) of the 2 nd check valve (80) that has a 2 nd through-hole (81 a).

Description

Electromagnetic pump

Technical Field

The utility model relates to an electromagnetic pump for fluid such as oil carries.

Background

There is known an electromagnetic pump having: a solenoid; a piston disposed in a cylinder having a fluid flow path extending in an axial direction of the solenoid; 1 st check valve; and a 2 nd check valve. The piston and the No. 2 check valve are both hollow. The 1 st check valve is disposed in the hollow of the piston.

For example, an electromagnetic pump described in patent document 1, which is known in the art, includes a solenoid connected to one side of a cylinder in the axial direction. In addition, the electrical measuring pump has: a piston that is axially movable in an axially extending flow path in the cylinder; 1 st check valve, it sets up in the hollow of the piston; and a 2 nd check valve disposed on the other axial side of the 1 st check valve in the flow passage.

The plunger is connected to the shaft portion of the solenoid. When the solenoid moves the piston in the flow passage from one side to the other side in the axial direction, the working oil located between the 2 nd check valve and the 1 st check valve in the axial direction passes through the 1 st check valve. When the piston is returned from one side to the other side in the axial direction by the solenoid, the working oil located on the other side in the axial direction than the piston is discharged from the pump outlet of the cylinder. Meanwhile, the working oil outside the cylinder passes through the inflow port provided in the cylinder and the 2 nd check valve.

Patent document 1: japanese patent laid-open publication No. 2011-21593

SUMMERY OF THE UTILITY MODEL

The electromagnetic pump described in patent document 1 has the following problems: in the assembly process of the electromagnetic pump, a process of fixing the 2 nd check valve in the flow passage of the cylinder is required, and thus the assembly process becomes complicated.

The utility model discloses a first mode provides an electromagnetic pump, and this electromagnetic pump has: a pump section having a cylinder having a fluid passage extending in an axial direction; a solenoid connected to an end surface of the cylinder on one side in the axial direction; a hollow piston having a wall at the other axial end thereof and axially movable in the flow path by the solenoid; a 1 st check valve including a 1 st elastic body and a 1 st valve body, the 1 st elastic body being disposed in the hollow of the piston, the 1 st valve body being biased by the 1 st elastic body toward a 1 st through-hole provided in the wall in the hollow of the piston; and a 2 nd check valve which is provided with a hollow, and which includes a 2 nd elastic body, a wall, and a 2 nd valve body, the 2 nd elastic body being disposed in the hollow, the wall being disposed at the other end portion in the axial direction, the 2 nd valve body being urged by the 2 nd elastic body toward a 2 nd through-hole provided in the wall in the hollow, wherein the 2 nd check valve is movable in the axial direction in the flow path, a 3 rd elastic body is disposed between the 2 nd check valve in the flow path and the piston in the axial direction, the 3 rd elastic body urging the 2 nd check valve and the piston in opposite directions in the axial direction, and the 2 nd check valve is urged by the 3 rd elastic body toward a surface of an inner wall surface of the cylinder which faces the wall of the 2 nd check valve having the 2 nd through-hole.

The electromagnetic pump according to the second aspect of the present invention is the electromagnetic pump according to the first aspect, wherein the flow path space of the cylinder body is a cylindrical space extending in the axial direction, and the piston is cylindrical.

A third aspect of the present invention is the electromagnetic pump of the second aspect, wherein the 2 nd check valve has a cylindrical shape, and the piston and the 2 nd check valve have the same diameter.

An electromagnetic pump according to a fourth aspect of the present invention is the electromagnetic pump according to any one of the first to third aspects, wherein the 3 rd elastic body is a coil spring, the piston has an annular convex portion that protrudes toward the other side on a surface of the other axial side of a wall provided at the other axial side end portion of the piston, the annular convex portion has the 1 st through hole, the 2 nd check valve has a convex portion that protrudes toward the one side on a surface of the one axial side of a wall provided at the one axial side end portion of the 2 nd check valve, the coil spring has the annular convex portion of the piston inserted into a coil of the one axial side end portion, and the convex portion of the 2 nd check valve is inserted into a coil of the other axial side end portion.

According to the utility model discloses, following electromagnetic pump is provided: in the assembling process of the electromagnetic pump, the work of fixing the 2 nd check valve to the cylinder body can be omitted, and the assembling process can be simplified.

Drawings

Fig. 1 is a perspective view of an electromagnetic pump of an embodiment.

Fig. 2 is a longitudinal sectional view of the electromagnetic pump.

Fig. 3 is a longitudinal sectional view of the electromagnetic pump in a state where energization to a coil of a solenoid is stopped.

Fig. 4 is a longitudinal sectional view of the electromagnetic pump immediately after the energization to the coil is started.

Fig. 5 is a longitudinal sectional view of the electromagnetic pump in a state where the plunger of the solenoid is moved to one end on the front side of the axially movable region.

Fig. 6 is a longitudinal sectional view of the electromagnetic pump immediately after the energization to the coil is stopped.

Description of the reference symbols

1: an electromagnetic pump; 10: a solenoid; 11: a shaft portion; 13: a plunger; 17: an iron core; 17 a: a flange portion; 17 b: a main body portion; 21: a yoke; 25: a bobbin; 29: a coil; 30: a housing; 30 a: a bottom; 30 b: a crimping part; 50: a pump section; 51: a cylinder body; 51 a: an inflow-side inner wall (a wall having a surface facing the front wall 81 of the 2 nd check valve 80); 52: an outlet of the pump; 53: an inflow port; 54: a flow path; 60: a piston; 61: a front wall; 61 a: a 1 st inlet through hole; 61 b: an annular projection; 62: a rear wall; 62 a: a 1 st outlet through hole; 70: 1 st check valve; 71: 1 st coil spring (1 st elastic body); 72: a 1 st valve core; 80: a 2 nd check valve; 81: a front wall; 81 a: a 2 nd inlet through hole; 82: a 2 nd coil spring (2 nd elastic body); 83: a 2 nd valve core; 84: a rear wall; 84 a: a 2 nd outlet through hole; 90: a 3 rd coil spring (3 rd elastic body); 91: a padding; 92: a guiding barrel.

Detailed Description

Hereinafter, an electromagnetic pump according to an embodiment of the present invention will be described with reference to the drawings. In the present embodiment, an electromagnetic pump used for transporting oil will be described. In the following drawings, in order to easily understand each structure, an actual structure may be different from the scale, the number, and the like of each structure.

In the drawings, an XYZ coordinate system is appropriately shown as a three-dimensional orthogonal coordinate system. In the XYZ coordinate system, the Z-axis direction is a direction parallel to the axial direction of the central axis J shown in fig. 1. The X-axis direction is a direction parallel to the short side direction of the electromagnetic pump shown in fig. 1. The Y-axis direction is a direction perpendicular to both the X-axis direction and the Z-axis direction.

In the following description, the positive side (+ Z side) in the Z-axis direction is referred to as "rear side", and the negative side (-Z side) in the Z-axis direction is referred to as "front side". The rear side and the front side are names used for explanation only, and do not limit the actual positional relationship and direction. Unless otherwise specified, a direction parallel to the central axis J (Z-axis direction) is simply referred to as "axial direction", a radial direction about the central axis J is simply referred to as "radial direction", and a circumferential direction about the central axis J, that is, a direction (θ direction) around the central axis J is simply referred to as "circumferential direction".

In addition, in the present specification, the axial direction extension includes a case of extending in a direction inclined in a range of less than 45 ° with respect to the axial direction, in addition to a case of extending strictly in the axial direction (Z-axis direction). In addition, in the present specification, the radial direction extension includes a case of extending in a direction inclined in a range of less than 45 ° with respect to the radial direction, in addition to a case of extending in a strictly radial direction, that is, a direction perpendicular to the axial direction (Z-axis direction).

The axial direction (Z-axis direction) in each drawing corresponds to the axial direction of the present invention. In addition, the axial rear side in each drawing corresponds to one side of the present invention. The front side in the axial direction in each drawing corresponds to the other side in the axial direction of the present invention.

< integral Structure >

Fig. 1 is a perspective view of an electromagnetic pump of an embodiment. As shown in fig. 1, the electromagnetic pump 1 has a solenoid 10 and a pump portion 50. The solenoid 10 and the pump section 50 are arranged in the axial direction. Specifically, the solenoid 10 is connected to the rear side in the axial direction of the pump section 50. Hereinafter, each component will be described in detail.

< solenoid 10 >

Fig. 2 is a longitudinal sectional view of the solenoid pump 1. As shown in fig. 2, the solenoid 10 has a housing 30, a bobbin 25, an iron core 17, a yoke 21, and a plunger 13.

(outer cover 30)

The cylindrical housing 30 is made of a magnetic metal material. The housing 30 has: a bottom portion 30a disposed on the rear side in the axial direction; and a pressure-bonding section 30b provided at one end of the front side in the axial direction. The shape of the cylindrical housing 30 is not limited to a strict cylindrical shape. But may also be polygonal in cross-sectional shape. That is, the configuration of the housing 30 may also be a configuration having a hollow and polygonal shape in cross section. Other cylindrical members among the members of the solenoid 10 may be configured to have a polygonal cross section and be hollow, without being limited to the housing 30.

The cylindrical body and the bottom portion 30a of the cylindrical case 30 are made of the same metal material and are molded by the same molding process. The cylindrical body and the bottom portion 30a may be molded by different molding steps, and the bottom portion 30a may be assembled to the cylindrical body in a subsequent step.

(reel 25)

A coil 29 for generating a magnetic force is wound around the bobbin 25. A cylindrical bobbin 25 made of a nonmagnetic material such as resin is disposed at the center in the axial direction in the cylinder of the housing 30.

(iron core 17)

The core 17 made of a magnetic material has a flange portion 17a extending radially outward on the front side in the axial direction. The portion of the core 17 other than the flange portion 17a is a main body portion 17 b. The body 17b is located in the cylinder of the bobbin 25. On the other hand, the flange 17a of the core 17 is positioned on the axial front side of the bobbin 25.

(yoke 21)

The yoke 21 made of a magnetic material is disposed at a position axially rearward of the core 17 in the cylinder of the bobbin 25. A gap G exists between the core 17 and the yoke 21.

(plunger 13)

The plunger 13 having a cylindrical shape and made of a magnetic material is movable in the axial direction in the cylinder of the yoke 21, and is guided to move in the axial direction by the yoke 21.

(shaft part 11)

The core 17 has a through circular hole along the core center axis. The shaft portion 11 penetrates through a through circular hole of the core 17. An axial rear end surface of the shaft portion 11 is in contact with an axial front end surface of the plunger 13. The shaft portion 11 is movable in the axial direction together with the plunger 13 while being guided to move in the axial direction by the iron core 17.

(coil 29)

The coil 29 is wound around the bobbin 25. The coil 29 is wound in the circumferential direction along the outer circumferential surface of the cylindrical portion 25a of the bobbin 25 on the radially outer side. Both ends of the coil 29 are electrically connected to the terminals 38. The bobbin 25 around which the coil 29 is wound is made of the same resin material as the terminal body portion 37.

When a current is caused to flow through the coil 29 by energization, a magnetic path is generated around the coil 29. Then, the plunger 13 is attracted from the rear side to the front side in the axial direction by magnetic force. At this time, the plunger 13 presses the shaft portion 11 and a later-described piston 60 of the pump portion 50 against an urging force of a later-described 3 rd coil spring 90 of the pump portion 50, and moves to the front side in the axial direction. On the other hand, when no current flows through the coil 29 due to the stoppage of energization, the magnetic path existing around the coil 29 disappears. Then, the plunger 13 attracted to the front side in the axial direction by the magnetic force is moved to the rear side in the axial direction together with the shaft portion 11 and the piston 60 of the pump portion 50 by the biasing force of the 3 rd coil spring 90.

In fig. 2, the plunger 13, the shaft portion 11, and the piston 60 of the pump portion 50 are moved to the rear side in the axial direction by stopping the energization to the coil 29.

< Pump part 50 >

The pump section 50 includes a metal cylindrical cylinder 51, a piston 60, a 1 st check valve 70, a 2 nd check valve 80, a 3 rd coil spring 90, a spacer 91, and a guide cylinder 92.

(Cylinder body 51)

The cylinder 51 has a cylindrical space extending in the axial direction. The cylinder 51 has: an inflow port 53 that communicates with the cylindrical space of the cylinder 51 on the axial front side; and a pump outlet 52 that communicates with the cylindrical space from the-X side at the axial rear side. The diameter of the inflow port 53 is smaller than the diameter of the cylindrical space. Of the inner walls of the cylinder 51, the inner wall at the front end in the axial direction in the above-described cylindrical space is an inflow inner wall 51 a.

(guide cylinder 92)

A cylindrical guide tube 92 is press-fitted into the cylinder of the cylinder 51. The guide cylinder 92 guides the axial movement of the piston 60 described later. Inside the cylinder of the guide cylinder 92 is a flow path 54 for oil as a fluid.

(piston 60)

The cylindrical piston 60 is disposed in a rear region in the axial direction in the cylinder of the guide cylinder 92. A rear wall 62, which is a wall on the rear side in the axial direction of the piston 60, contacts the front end surface of the shaft portion 11 of the solenoid 10.

In the piston 60, a first inlet through-hole 61a is provided in a front wall 61 that is a front wall in the axial direction. The piston 60 has a double cylindrical structure.

(1 st check valve 70)

A 1 st check valve 70 is disposed in the cylinder of the piston 60. The 1 st check valve 70 has: a 1 st coil spring 71 as a 1 st elastic body disposed in the cylinder inside the double cylindrical piston 60; and a 1 st spool 72 biased from the rear side toward the front side in the axial direction by a 1 st coil spring 71.

In fig. 2, the 1 st valve body 72 is pressed against the front wall 61 of the piston 60 by the biasing force of the 1 st coil spring 71, and closes the 1 st inlet through hole 61a of the front wall 61.

(No. 2 check valve 80)

The 2 nd check valve 80 is disposed in a region on the axial front side of the 1 st check valve 70 in the flow passage 54. The 2 nd check valve 80 also has a double cylindrical shape, as in the 1 st check valve 70. The 2 nd check valve 80 has a front wall 81 as a wall on the axial front side. The 2 nd check valve 80 has: a 2 nd coil spring 82 as a 2 nd elastic body disposed in an inner cylinder of the double cylinders; and a 2 nd spool 83 biased from the rear side toward the front side in the axial direction by a 2 nd coil spring 82.

In fig. 2, the 2 nd spool 83 is pressed against the front wall 81 of the 2 nd check valve 80 by the biasing force of the 2 nd coil spring 82 to close the 2 nd inlet through-hole 81a of the front wall 81.

The diameters of the piston 60 and the 2 nd check valve 80 are identical to each other. The piston 60 moves in the axial direction with its outer peripheral surface in close contact with the inner peripheral surface of the guide cylinder 92. The 2 nd check valve 80 has its outer peripheral surface in close contact with the inner peripheral surface of the guide cylinder 92.

(3 rd coil spring 90)

A 3 rd coil spring 90 as a 3 rd elastic body is disposed in a region between the 2 nd check valve 80 and the piston 60 in the flow passage 54. The 3 rd coil spring 90 biases the 2 nd check valve 80 from the rear side toward the front side in the axial direction. The 2 nd check valve 80 thus biased has an annular spacer 91 interposed between the inflow side inner wall 51a of the cylinder 51. The center through-hole of the packing 91 communicates with the inflow port 53 of the cylinder 51. The center through-hole of the packing 91 communicates with the 2 nd inlet through-hole 81a of the 2 nd check valve 80.

The 3 rd coil spring 90 biases the piston 60 from the front side toward the rear side in the axial direction. The 3 rd coil spring 90 biases the shaft portion 11 of the solenoid 10 and the plunger 13 from the front side toward the rear side in the axial direction via the piston 60.

An annular convex portion 84b that protrudes toward the rear side in the axial direction is provided on the outer surface of the rear wall 84 of the 2 nd check valve 80. An annular convex portion 61b that protrudes toward the front side in the axial direction is provided on the outer surface of the front wall 61 of the piston 60. The annular convex portion 61b of the piston 60 is inserted into the rear end portion in the axial direction of the 3 rd coil spring 90, and the annular convex portion 84b of the 2 nd check valve 80 is inserted into the front end portion in the axial direction.

(operation of Pump section 50)

Fig. 3 is a longitudinal sectional view of the electromagnetic pump 1 in a state where the energization to the coil 29 of the solenoid 10 is stopped. In fig. 3, the housing 30 and the terminal body portion 37 of the solenoid 10 are not illustrated for ease of viewing. In fig. 4, 5, and 6, which will be described later, the housing 30 and the terminal body portion 37 of the solenoid 10 are similarly omitted.

In fig. 3, the plunger 13 and the shaft portion 11 of the solenoid 10 and the piston 60 of the pump portion 50 are in a state of moving toward the rear side in the axial direction. The 1 st spool 72 of the 1 st check valve 70 is in a state of closing the 1 st inlet through hole 61a of the front wall 61 of the piston 60. The 2 nd spool 83 of the 2 nd check valve 80 is in a state of closing the 2 nd inlet through-hole 81a of the front wall 81 of the 2 nd check valve 80.

A 1 st through-outlet port 62a is provided in a rear wall 62, which is a wall on the rear side in the axial direction of the piston 60. The hollow of the piston 60 communicates with a region of the flow path 54 on the rear side in the axial direction of the piston 60 through the 1 st outlet through-hole 62 a.

A 2 nd through-outlet port 84a is provided in a rear wall 84, which is a wall on the axial rear side of the 2 nd check valve 80. The region between the 2 nd check valve 80 and the piston 60 in the flow passage 54 communicates with the hollow of the 2 nd check valve 80 through the 2 nd outlet through port 84 a.

Fig. 4 is a longitudinal sectional view of the electromagnetic pump 1 immediately after the energization of the coil 29 of the solenoid 10 is started. In fig. 4, the plunger 13 and the shaft 11 of the solenoid 10 and the piston 60 of the pump section 50 start to move from the rear side to the front side in the axial direction by starting energization of the coil 29. When the volume of the region between the 2 nd check valve 80 and the piston 60 in the flow path 54 is reduced by this movement, the pressure of the oil in this region rises. At the same time, the pressure of the oil in the hollow of the 2 nd check valve 80 communicating with the above-described region also rises. At this time, the oil in the 2 nd check valve 80 is pressurized to press the 2 nd spool 83 against the front wall 81 of the 2 nd check valve 80 to strongly close the 2 nd inlet through hole 81a of the front wall 81. Therefore, the oil in the hollow of the 2 nd check valve 80 does not flow backward to the inflow port 53 of the cylinder 51 through the 2 nd inlet through-hole 81a of the front wall 81.

The pressure of the oil passing through the area between the 2 nd check valve 80 and the piston 60 in the flow passage 54 increases, and the 1 st spool 72 of the 1 st check valve 70 moves from the front side to the rear side in the axial direction against the urging force of the 1 st coil spring 71. By this movement, the 1 st inlet through hole 61a of the front wall 61 of the piston 60 is opened, and the oil between the 2 nd check valve 80 and the piston 60 flows into the hollow of the piston 60 through the 1 st inlet through hole 61 a. Further, the oil in the hollow of the piston 60 flows into the region on the rear side in the axial direction of the piston 60 in the flow passage 54 through the 1 st through-outlet port 62a of the rear wall 62 of the piston 60. The volume of this region increases as the piston 60 moves to the axial front side. Therefore, even if the oil in the hollow of the piston 60 flows into this region, the pressure of the oil in this region hardly increases.

Fig. 5 is a longitudinal sectional view of the electromagnetic pump 1 in a state where the plunger 13 of the solenoid 10 has moved to one end on the front side of the axial movable region. In fig. 5, the pressure of the oil in the region between the 2 nd check valve 80 and the piston 60 in the flow passage 54 is in a state lower than the urging force of the 1 st coil spring 71 of the 1 st check valve 70. Therefore, the 1 st valve body 72 of the 1 st check valve 70 is pressed against the front wall 61 of the piston 60 by the biasing force of the 1 st coil spring 71 to close the 1 st inlet through hole 61a of the front wall 61.

Fig. 6 is a longitudinal sectional view of the electromagnetic pump 1 immediately after the energization to the coil 29 of the solenoid 10 is stopped. In fig. 6, the plunger 13 and the shaft portion 11 of the solenoid 10 and the piston 60 of the pump portion 50 start to move from the front side to the rear side in the axial direction by the biasing force of the 3 rd coil spring 90. When the volume of the region between the 2 nd check valve 80 and the piston 60 in the flow passage 54 increases due to this movement, the pressure of the oil in this region decreases. At the same time, the pressure of the oil in the hollow of the 2 nd check valve 80 communicating with this area is also reduced. At this time, the pressure of the oil in the hollow of the 2 nd check valve 80 is lower than the pressure of the oil in the external pipe communicating with the inlet 53 of the cylinder 51 outside the cylinder 51. Then, the oil in the outside pipe moves the 2 nd spool 83 from the front side toward the rear side in the axial direction against the urging force of the 2 nd coil spring 82 of the 2 nd check valve 80. By this movement, the 2 nd inlet through-hole 81a of the front wall 81 of the 2 nd check valve 80 is opened. The oil in the external pipe connected to the cylinder 51 flows into the hollow of the 2 nd check valve 80 through the inflow port 53 of the cylinder 51 and the 2 nd inlet through-hole 81a of the front wall 81 of the 2 nd check valve 80. By this inflow, the oil in the hollow of the 2 nd check valve 80 flows into the area between the 2 nd check valve 80 and the piston 60 in the flow passage 54 through the 2 nd outlet through-hole 84a of the rear wall 84 of the 2 nd check valve 80.

On the other hand, in the region of the flow passage 54 on the axial rear side of the piston 60, the volume decreases as the piston 60 moves rearward, and therefore the oil pressure increases. In addition, the pressure of the oil in the hollow of the piston 60 communicating with this region through the 1 st through-outlet port 62a also rises. The oil in the hollow of the piston 60 increases in pressure and presses the 1 st spool 72 of the 1 st check valve 70 against the front wall 61 of the piston 60, so the 1 st inlet through hole 61a of the front wall 61 is strongly closed by the 1 st spool 72. Therefore, the oil in the hollow of the piston 60 does not flow backward between the piston 60 and the 2 nd check valve 8 in the flow path 54 through the 1 st inlet through-hole 61a of the front wall 61.

The oil that has passed through the region of the flow path 54 on the axial rear side of the piston 60 is discharged to the outside of the cylinder 51 through the pump outlet of the cylinder 51 due to the pressure increase.

< Effect/Effect of electromagnetic Pump 1 >

(1) As is apparent from fig. 3 to 6, the 2 nd check valve 80 disposed in the flow passage 54 of the cylinder 51 is pressed toward the inflow side inner wall 51a of the cylinder 51 by the biasing force of the 3 rd coil spring regardless of the axial movement position of the piston 60. Therefore, the 2 nd check valve 80 is axially locked at a position where the spacer 91 is interposed between the inflow side inner wall 51a of the cylinder 51, regardless of the axial movement position of the piston 60. Therefore, in the electromagnetic pump 1 of the embodiment, it is not necessary to fix the 2 nd check valve 80 at a position where a spacer is interposed between the inflow side inner wall 51a of the cylinder 51. Thus, according to the electromagnetic pump 1 of the embodiment, the step of fixing the 2 nd check valve 80 to the cylinder 51 can be omitted in the step of assembling the electromagnetic pump 1, thereby simplifying the assembling step.

The assembly worker can install the shim 91 and the 2 nd check valve 80 in the flow path 54 by simply putting the shim 91 and the 2 nd check valve 80 into the flow path 54 from an opening for passing through the solenoid shaft portion provided in the cylinder 51.

(2) In the electromagnetic pump 1 of the embodiment, the flow path 54 for housing the piston 60 and the 2 nd check valve 80 can be provided in the cylinder 51 by providing only one cylindrical space extending in the axial direction, which is obtained by cutting the cylinder 51 with a drill or the like. Therefore, productivity of the cylinder 51 can be improved as compared with a conventional structure in which a complicated-shaped flow path is provided in the cylinder.

(3) In the electromagnetic pump 1 of the embodiment, the entire circumferential region of the outer circumferential surface of the piston 60 is brought into close contact with the inner circumferential surface of the guide cylinder 92, and the entire circumferential region of the outer circumferential surface of the 2 nd check valve 80 is brought into close contact with the inner circumferential surface of the guide cylinder 92. Therefore, according to the electromagnetic pump 1 of the embodiment, the oil existing at the rear side in the axial direction of the piston 60 can be prevented from flowing backward to the front side from the gap between the outer circumferential surface of the piston 60 and the inner circumferential surface of the guide tube 92. Further, according to the electromagnetic pump 1 of the embodiment, the oil existing between the 2 nd check valve 80 and the piston 60 can be prevented from flowing backward to the front side from the gap between the outer peripheral surface of the 2 nd check valve 80 and the inner peripheral surface of the guide tube 92.

(4) The electromagnetic pump 1 according to the embodiment supports the rear side in the axial direction of the 3 rd coil spring 90 by the annular convex portion 61b of the piston 60 regardless of the axial movement position of the piston 60. In addition, the electromagnetic pump 1 according to the embodiment supports the forward side in the axial direction of the 3 rd coil spring 90 by the annular convex portion 84b of the 2 nd check valve 80 regardless of the axial movement position of the piston 60. Therefore, according to the electromagnetic pump 1 of the embodiment, the 3 rd coil spring 90 can be stably supported regardless of the movement of the piston 60 in the axial direction.

While the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications and changes can be made within the scope of the present invention. The embodiments and modifications thereof are included in the scope and gist of the invention, and are also included in the invention described in the claims and equivalent ranges thereof.

Claims

1. An electromagnetic pump, comprising:

a pump section having a cylinder having a fluid passage extending in an axial direction;

a solenoid connected to an end surface of the cylinder on one side in the axial direction;

a hollow piston having a wall at the other axial end thereof and axially movable in the flow path by the solenoid;

a 1 st check valve including a 1 st elastic body and a 1 st valve body, the 1 st elastic body being disposed in the hollow of the piston, the 1 st valve body being biased by the 1 st elastic body toward a 1 st through-hole provided in the wall in the hollow of the piston; and

a 2 nd check valve having a hollow, 2 nd elastic body, a wall, and a 2 nd valve element, the 2 nd elastic body being disposed in the hollow, the wall being disposed at the other end in the axial direction, the 2 nd valve element being urged by the 2 nd elastic body toward a 2 nd through-hole provided in the wall in the hollow,

it is characterized in that the preparation method is characterized in that,

the 2 nd check valve is axially movable within the flow path,

a 3 rd elastic body is disposed between the 2 nd check valve and the piston in the axial direction of the flow path, the 3 rd elastic body urging the 2 nd check valve and the piston in opposite directions in the axial direction,

the 2 nd check valve is biased by the 3 rd elastic body toward a surface of the inner wall surface of the cylinder, the surface facing the wall of the 2 nd check valve having the 2 nd through-hole.

2. The electromagnetic pump of claim 1,

the flow path space of the cylinder is a cylindrical space extending in the axial direction,

the piston is cylindrical in shape.

3. The electromagnetic pump of claim 2,

the 2 nd check valve is cylindrical in shape,

the diameters of the piston and the 2 nd check valve are the same as each other.

4. An electromagnetic pump according to any one of claims 1 to 3,

the 3 rd elastic body is a coil spring,

the piston has an annular convex portion protruding toward the other side in the axial direction on a surface on the other side in the axial direction of a wall provided at the other side end portion in the axial direction of the piston,

the annular projection has the 1 st through-hole,

the 2 nd check valve has a convex portion protruding toward one side on a surface on one side in the axial direction of a wall provided at one end portion in the axial direction of the 2 nd check valve,

the coil spring has an annular projection of the piston inserted into a coil of one axial end, and a projection of the 2 nd check valve inserted into a coil of the other axial end.