JP2020056333A - Electromagnetic pump and combustion device employing the same - Google Patents

Abstract

To increase a return quantity of fuel from an oil feeding pipe during an operation stop time of a combustion device and secure stability in fuel supply in a driving time of the combustion device in an electromagnetic pump.SOLUTION: An electromagnetic pump 1 comprises: a suction joint 2; a discharge joint 3; a tubular cylinder 4 disposed therebetween; an electromagnetic coil 5 which generates a magnetic force in an intermittent manner in the cylinder 4; a plunger 6 which is disposed inside of the cylinder 4 and moved reciprocally by the magnetic force of the electromagnetic coil 5; a suction check valve unit 8 which is disposed within the plunger 6; a discharge check valve unit 33 which is provided within the discharge joint 3 and discharges a fluid (fuel) sucked by the plunger 6; and a push-up member 9 which is disposed on an end portion of the plunger 6 and pushes up the discharge check valve unit 33 so as to open the same. The suction check valve unit 8 includes a suction valve 81, a suction valve seat 82, and a bypass flow passage 80 in which the fuel is communicated between the inside of the plunger 6 and the suction joint 2 when the suction valve 81 is pressed by the suction valve seat 82.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an electromagnetic pump that supplies liquid fuel to a combustion section of a combustion device used for heating, hot water supply, and the like, and a combustion device using the same.

  2. Description of the Related Art Conventionally, there has been known an electromagnetic pump configured to reciprocate a plunger contained in a tubular cylinder in an axial direction by a periodic change of a magnetic force generated by an electromagnetic coil to suck and discharge a liquid. Have been. This type of electromagnetic pump is attached to, for example, a combustion device used for heating or hot water supply, and supplies fuel such as kerosene stored in a fuel tank of the combustion device to a combustion unit.

  The fuel discharged by the electromagnetic pump is supplied to a combustion unit via an oil supply pipe, and is vaporized and burned in the combustion unit. However, when the operation of the combustion device is stopped, the oil pipe is no longer cooled by the flow of fuel and receives the residual heat of the combustion part, so that its internal temperature rises, and as a result, the fuel in the oil pipe becomes May thermally expand, causing excess fuel to drip into the combustion section. As described above, when excess fuel is dripped into the combustion section, the combustion stoppage is delayed or the fuel is wasted in order to burn them off. In addition, if excess fuel remains in the combustion part, it becomes unburned gas and produces odor.If the excess fuel is tarred and accumulated repeatedly, it may cause ignition delay and other problems in the combustion part. There is a risk of causing this.

  Therefore, there is known an electromagnetic pump in which when the operation of the combustion device is stopped, a discharge check valve is opened to return fuel remaining in an oil feed pipe to a fuel tank (for example, see Patent Document 1). In the electromagnetic pump described in Patent Literature 1, a push-up member protruding toward the discharge check valve is provided between the discharge check valve and the plunger, and after the operation of the combustion device is stopped, the plunger is moved during normal operation. The discharge check valve is moved up to the upper limit point beyond the dead center, and is opened by pushing up the discharge check valve. As a result, when the discharge check valve is opened, the fuel in the oil feed pipe returns to the fuel tank side due to a drop from the liquid level of the fuel tank. When the plunger returns from the upper limit point to the top dead center, a negative pressure is instantaneously generated in the cylinder, and a part of the fuel remaining in the oil feed pipe is sucked into the cylinder.

Japanese Patent No. 2698018

  By the way, in the electromagnetic pump described in Patent Document 1, when the discharge check valve is pushed up by the push-up member and opened, the suction check valve provided at the suction side end of the plunger is in the closed state. Therefore, the fuel returned from the oil supply pipe into the cylinder is returned to the fuel tank via the clearance between the cylinder and the plunger. However, there is usually little clearance between the cylinder and the plunger, which limits the amount of fuel returned. If the clearance between the cylinder and the plunger is increased, the amount of fuel returned can be increased, but the reciprocating motion of the plunger becomes unstable and the pump pressure also drops, resulting in unstable fuel supply during operation. May be caused. In addition, since the plunger is created by grinding the outer periphery of the magnetic body, it is not easy to maintain the clearance between the cylinder and the cylinder with high accuracy, and it is difficult to solve the above-mentioned problem by optimizing the clearance. is there.

  The present invention has been made to solve the above problems, and can stably increase the amount of fuel returned from an oil feed pipe to a fuel tank when the operation of a combustion device is stopped, and furthermore, the stability of fuel supply during operation. And a combustion device using the same.

  In order to solve the above problems, the present invention is an electromagnetic pump that supplies a fluid in a fuel tank to a combustion unit via an oil feed pipe, wherein the electromagnetic pump comprises a suction joint forming a fluid suction port and a fluid discharge port. A discharge cylinder, a tubular cylinder disposed between the suction joint and the discharge joint, an electromagnetic coil disposed outside the cylinder to generate a magnetic force intermittently, and disposed inside the cylinder. A plunger that reciprocates in an axial direction due to an intermittent magnetic force generated by the electromagnetic coil, an urging portion that balances the magnetic force generated by the electromagnetic coil and holds the plunger reciprocally, and the plunger. A suction check valve portion provided inside to suction the fluid from the suction joint; and a discharge valve provided inside the discharge joint to discharge the fluid sucked by the plunger. A check valve portion, and a push-up member disposed at an end of the plunger on the discharge check valve portion side and pushing up to enable opening of the discharge check valve, wherein the suction check valve portion is A suction valve, a suction valve seat, a suction spring for pressing the suction valve toward the suction valve seat, and the inside of the plunger when the suction valve is pressed against the suction valve seat by the suction spring. And a bypass flow path for communicating a fluid with the suction joint.

  In the above-described electromagnetic pump, it is preferable that the bypass passage is formed in the suction valve seat.

  In the above electromagnetic pump, it is preferable that the suction valve seat is made of an injection-molded resin.

  In the electromagnetic pump, the suction valve has a substantially hemispherical surface facing the suction valve seat, the suction valve seat has a substantially mortar-shaped surface facing the suction valve, and the bypass flow path Preferably, the groove is formed by a groove-shaped path formed in the substantially mortar-shaped surface.

  In the above electromagnetic pump, it is preferable that the suction valve is made of a non-flexible resin.

  The electromagnetic pump is preferably used for a combustion device.

  According to the present invention, when the discharge check valve portion is opened, the fluid connected to the discharge joint, for example, the fluid returned from the oil supply pipe to the cylinder, not only the clearance between the cylinder and the plunger, but also via the bypass path. It flows to the suction joint and can be returned to the fuel tank. Therefore, the return amount of fuel can be increased stably. Further, since there is no need to increase the clearance between the cylinder and the plunger, the stability of fuel supply during driving can be ensured.

The side view showing the schematic structure of the combustion device provided with the electromagnetic pump concerning one embodiment of the present invention. The sectional side view of the same electromagnetic pump. (A) is a side view of the electromagnetic pump, (b) is a front view, (c) a plan view. (A) is a top view of a protrusion member, (b) is a front view. (A) is a side sectional view of the suction valve and the suction valve seat, (b) is a front view of the suction valve seat, (c) is a cross-sectional view taken along line AA of (a), (d) is B of (a) -B line sectional drawing. The figure which shows the operation time chart of the oil fan heater using the said electromagnetic pump. (A) is a side cross-sectional view showing a stopped state of the electromagnetic pump, (b) is a side cross-sectional view showing a state in which the plunger in a reciprocating operation is at a bottom dead center position in a supply control mode of the electromagnetic pump, ( c) is a side view showing the state where the plunger is at the position of the top dead center, (d) is a side view showing the state where the plunger moves down toward the bottom dead center, and (e) is a supply of the electromagnetic pump. FIG. 3 is a side view showing a state in which the plunger is at an upper limit position in a control mode.

  An electromagnetic pump according to an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, the electromagnetic pump 1 of the present embodiment is incorporated in a combustion device used for heating, hot water supply, and the like, in this case, an oil fan heater 10 for heating installed indoors.

  The oil fan heater 10 includes a combustion unit 11 and a fuel tank 12 in which fuel is stored. The fuel tank 12 is disposed below the oil fan heater 10, and the electromagnetic pump 1 is mounted at an appropriate position above the fuel tank 12 so as to supply fuel from the fuel tank 12 to the combustion unit 11. The electromagnetic pump 1 and the combustion section 11 are connected by an oil feed pipe 13. The nozzle tip 13 a of the oil feed pipe 13 extends to near the center in the combustion section 11. The combustion unit 11 is a normal burner that ignites with an igniter, and the fuel guided therein is vaporized inside at a high temperature and diffuses from a number of small holes (not shown) formed on the upper peripheral surface. When it is burned.

  The oil fan heater 10 includes a control device 14 that outputs a drive pulse signal for controlling the drive state of the electromagnetic pump 1 and a cartridge 15 for supplying a fixed amount of fuel to the fuel tank 12. The control device 14 is connected to a terminal of the electromagnetic pump 1 via a cable 14a.

  As shown in FIG. 2, the electromagnetic pump 1 is attached to a fuel tank 12 and is connected to a suction joint 2 that forms a suction port 20 for a fluid (hereinafter, referred to as fuel), and is connected to an oil feed pipe 13, and a fuel discharge port 30. , A tubular cylinder 4 disposed between the suction joint 2 and the discharge joint 3, and an electromagnetic coil 5 for generating a magnetic force intermittently in accordance with a drive pulse signal received from the control device 14. And a plunger 6 disposed inside the cylinder 4 and reciprocating in the axial direction by a magnetic force generated by the electromagnetic coil 5.

  The suction joint 2 is mainly composed of a suction cylinder 21 fitted to the lower end of the cylinder 4. The suction cylinder 21 has a through-hole 22 penetrating the inside thereof in the up-down direction, and its outer shape is gradually tapered downward from the lower end of the cylinder 4. The suction cylinder 21 of this example has a four-stage configuration. A cylindrical portion 22a which is larger than the diameter of the through hole 22 and in which the cylinder 4 is inserted is formed in the upper portion of the suction cylinder 21. A ring fitting portion 22b is formed on the upper surface of the suction cylinder 21 to fit an O-ring R1 for sealing between the suction joint 2 and the cylinder 4.

  An external filter 23 is attached to a lowermost portion of the suction cylinder 21. The external filter 23 is composed of a bottomed tubular body 23a having an open upper surface, and a mesh member 23b provided in the tubular body 23a. The cylindrical body 23a only needs to be able to hold the mesh material 23b, and a plurality of liquid inflow openings (not shown) are formed on its side peripheral surface and bottom surface. The external filter 23 is externally fitted to the lowermost stage of the suction cylinder 21 of the suction joint 2. Thus, the fuel filtered by the mesh material 23b is sucked into the suction port 20 of the suction joint 2.

  The discharge joint 3 mainly includes a discharge cylinder 31 that is fitted to the upper end of the cylinder 4. The discharge cylinder 31 has a through hole 32 penetrating the inside thereof in the up-down direction, and its outer shape is gradually tapered upward from the upper end side of the cylinder 4. The discharge cylinder 31 of this example has a two-stage configuration.

  The through hole 32 of the discharge joint 3 has a lower cylindrical portion 32a in which the cylinder 4 is inserted, a middle cylindrical portion 32b in which a discharge valve and the like are arranged, and an upper cylindrical portion 32c forming the discharge port 30. A ring fitting portion 32d is formed between the lower cylindrical portion 32a and the middle cylindrical portion 32b, into which an O-ring R2 for sealing between the discharge joint 3 and the cylinder 4 is fitted. An orifice portion 32e for controlling the flow rate of fuel discharged from the discharge port 30 is provided between the middle cylindrical portion 32b and the upper cylindrical portion 32c. An external thread for connecting the oil feed pipe 13 is formed on the outer periphery of the upper portion of the discharge cylinder 31.

  The discharge joint 3 has a discharge check valve portion 33 that discharges the liquid fuel sucked by the plunger 6 to the discharge port 30. The discharge check valve portion 33 includes a substantially cylindrical discharge valve 33a housed in the middle cylindrical portion 32b, a discharge valve seat 33b fitted inside the lower cylindrical portion 32a to the middle cylindrical portion 32b to receive the discharge valve 33a, A discharge spring 33c for urging the valve 33a toward the discharge valve seat 33b.

  The electromagnetic coil 5 is formed by winding a conductive wire around a coil bobbin 51 made of a non-magnetic material. The coil bobbin 51 has an axis around which the wire is wound, and flange portions provided at upper and lower ends thereof, respectively. The inner diameter of the coil bobbin 51 is set to be slightly larger than the outer diameter of the cylinder 4 so that a gap is formed between the coil bobbin 51 and the cylinder 4.

  Ring-shaped magnetic members 52 and 53 are fitted into the gap between the coil bobbin 51 and the cylinder 4 from the upper and lower portions, respectively, so that the inside thereof together with the plunger 6 is formed as a magnetic path. The position and length dimension of each of the magnetic bodies 52 and 53 are set such that each of the distal ends is separated by a predetermined length in a state where the magnetic bodies 52 and 53 are fitted to the cylinder 4. Is set at a position separated from the upper end by a predetermined distance. Thereby, when the electromagnetic coil 5 is energized, a magnetic flux for moving the plunger 6 upward is generated.

  A yoke 54 made of a U-shaped magnetic material is externally fitted to each of the magnetic bodies 52 and 53. As shown in FIGS. 3A to 3C, the yoke 54 forms an external magnetic path and functions as a part of the structural material of the electromagnetic pump 1. On the four surfaces of the outer periphery of the electromagnetic coil 5 except for the vertical plate of the yoke 54, rotation preventing portions 55 are attached so that the electromagnetic coil 5 does not rotate around the cylinder 4 as an axis. The detent part 55 is connected to the upper part of the horizontal plate above the yoke 54 with screws. A horizontal mounting plate 56 is integrated with the lower horizontal plate of the yoke 54, and the electromagnetic pump 1 is mounted to the fuel tank 12 of the oil fan heater 10 via the mounting metal 56.

  A terminal block 57 protruding outward is provided on the flange above the coil bobbin 51. The terminal block 57 is provided with a connection terminal 57a, and a lead wire for transmitting a drive pulse signal output from the control device 14 is connected to the connection terminal 57a. An end of the lower horizontal plate portion of the yoke 54 opposite to the vertical plate portion is bent upward, and a power supply IC regulator 58 is provided at this bent portion via a screw. The drive pulse signal input from control device 14 to connection terminal 57a is output to coil bobbin 51 via power supply IC regulator 58, and electromagnetic coil 5 is intermittently excited according to the received drive pulse signal.

  In addition, the electromagnetic pump 1 has an urging portion 7 disposed inside the cylinder 4 and holding the plunger 6 in a reciprocating manner in balance with the magnetic force generated by the electromagnetic coil 5 (see FIG. 2 again). In this example, the urging portion 7 includes a lower spring 71 provided between the bottom of the plunger 6 and the lower end of the cylinder 4, and an upper portion provided between the upper portion of the plunger 6 and the lower end of the discharge valve seat 33b. And a spring 72.

  The plunger 6 is formed in a substantially cylindrical shape for flowing the liquid, and its outer diameter is set slightly smaller than the inner diameter of the cylinder 4. The plunger 6 is mainly composed of a lower cylinder portion 61 and an upper cylinder portion 62 having a smaller diameter than the lower cylinder portion 61. The upper end of the upper cylinder portion 62 has an outer peripheral edge while an opening peripheral edge projects. Are recesses 63. A suction check valve portion 8 is provided in the lower cylinder portion 61 (end portion on the suction joint 2 side) of the plunger 6. The suction check valve portion 8 opens when the plunger 6 moves downward, closes when the plunger 6 moves upward, sucks fuel from the suction joint 2 side, and causes the fuel to flow to the discharge joint 3 side.

  Further, the plunger 6 has a push-up member 9 which is disposed at an end on the discharge check valve portion 33 side and pushes up so that the discharge check valve portion 33 can be opened. As shown in FIGS. 4A and 4B, the push-up member 9 includes a push-up shaft 91, an extension piece 92 extending in a wing shape in four directions when viewed from the axial direction of the push-up shaft 91, A hook portion 93 formed at the extension end of the projection piece 92 and engaged with the plunger 6. The lower part of the extension piece 92 is fitted in the upper cylindrical part 62 of the plunger 6, and a part thereof abuts on the inner peripheral surface of the upper cylindrical part 62 (see also FIG. 2). The hook portion 93 is engaged with a concave portion 63 provided on the outer peripheral edge of the upper end of the plunger 6. In this manner, by sandwiching the upper cylindrical portion 61 of the plunger 6 between the extension piece 92 and the hook portion 93, the push-up member 9 is fixed to the plunger 6, and reciprocates with the plunger 6. In addition, the extension piece 92 also extends to the distal end side of the protrusion shaft 91 beyond the hook portion 93, and by adopting such a shape, the strength of the hook portion 93 having a fine shape can be improved. .

  The suction check valve portion 8 includes a suction valve 81 provided inside the plunger 6 at a position on the side of the suction joint 2, a suction valve seat 82 fitted inside the lower end of the plunger 6 and serving as a seat for the suction valve 81, A suction spring 83 for urging the suction valve 81 toward the suction valve seat 82 (see FIG. 2 again).

  As shown in FIGS. 5A to 5D, the suction valve 81 has a substantially hemispherical surface 81a on the surface facing the suction valve seat. In addition, since the suction valve 81 of this embodiment is spherical, the surface facing the suction valve seat 82 is substantially hemispherical. The suction valve 81 is preferably made of a non-flexible resin. If it is made of an inflexible resin, the change over time of the suction valve 81 is small, so that the operation stability can be improved. If the suction valve 81 is flexible, when it is pressed by the suction valve seat 82, there is a possibility that the suction valve 81 will fit into the suction valve seat 82 or block the bypass passage 80. These dangers can be prevented by adopting the nature. Examples of the non-flexible resin include nylon and polypropylene.

  The suction valve seat 82 is a barrel-shaped member, and the upper part 82b and the lower part 82c sandwiching the center part 82a are each formed slightly thinner and tapered than the center part 82a. The suction valve seat 82 is provided with a through hole 82d penetrating in the up-down direction, and the upper end side opening and the lower end side opening of the through hole 82d are respectively substantially mortar-shaped surfaces 82e. The generally mortar-shaped surface 82e of the upper end side opening has a concave curved surface facing the suction valve 81 and for receiving the suction valve 81 having a convex curved surface.

  The electromagnetic pump 1 has a bypass flow path 80 for communicating fuel between the inside of the plunger 6 and the suction joint 2 when the suction valve 81 is pressed against the suction valve seat 82 by the suction spring 83. In the present embodiment, the bypass passage 80 is formed in the suction valve seat 82. Specifically, as shown in FIGS. 5A, 5C, and 5D, the bypass flow path 80 is formed by a groove-shaped path 80a formed in the substantially mortar-shaped surface 92e of the suction valve seat 82. .

  When the suction valve 81 is pressed by the suction valve seat 82, the groove-shaped path 80a is located in the projection plane of the suction valve 81 with respect to the suction valve seat 82, and is disposed to be orthogonal to the projection plane. That is, in the substantially mortar-shaped surface 92e, the groove-shaped path 80a is formed in a range smaller than the radius of the spherical suction valve 81, but the upper end of the groove-shaped path 80a Even when pressed by 82, it is not covered by the suction valve 81 and forms a bypass opening 80b (particularly, see FIG. 5D). With the provision of the bypass passage 80, even when the suction valve 81 is pressed by the suction valve seat 82, the suction check valve portion 8 is not completely closed. The bypass passage 80 is designed to be shorter than the length of the plunger 6.

  The suction valve seat 82 is preferably made of injection-molded resin. The suction valve seat 82 has a simple structure, and can be manufactured at low cost by injection molding with resin. The upper end and the lower end of the groove-like path 80a are each formed in a substantially mortar-shaped surface 82e. That is, the upper portion 82b and the lower portion 82c are formed symmetrically with respect to the central portion 82a, and there is no need to distinguish between the upper and lower portions when attaching the suction valve seat 82 to the plunger 6.

  The control device 14 executes a supply control mode in which a drive pulse signal is output to the electromagnetic coil 5 to control a predetermined fuel to be supplied to the combustion unit 11, and when the supply of fuel is stopped, the plunger 6 is discharged and stopped. A fire extinguishing control mode is executed in which the discharge valve 33a is moved up to the valve section 33 side and pushed up by the push-up member 9 disposed at the upper end of the plunger 6 to open the discharge check valve section 33 for a predetermined time. As shown in FIG. 6, in the supply control mode, when the operation switch is pressed by the user, the carburetor residual heat heater is driven first, and then the combustion blower fan is started. Then, when a carburetor (not shown) of the combustion section 11 is preheated to a certain temperature, oil supply driving by the electromagnetic pump 1 and combustion of fuel by the ignition igniter are started at the same time. After the ignition by the ignition igniter, the hot air blower fan operates, and the heat generated by the combustion of the fuel in the combustion unit 11 is blown out as hot air by the hot air blower fan. Thereafter, when the temperature of the vaporizer reaches a sufficient temperature due to the combustion of the combustion unit 11, the operation of the vaporizer residual heater ends.

  When the user releases the operation switch, oil supply by the electromagnetic pump 1 is stopped, and the fire extinguishing control mode is executed. In this fire extinguishing control mode, the oil supply return drive is performed for a predetermined time, and after the fire extinguishing control mode ends, the combustion blower fan and the hot air blowing fan are sequentially stopped.

  Here, the operation of the electromagnetic pump 1 in the supply control mode and the fire extinguishing control mode will be described with reference to FIGS. In the illustrated example, the stop position, the top dead center, the bottom dead center, and the upper limit point are shown with reference to the tip of the push-up member 9, but since the push-up member 9 and the plunger 6 move together, The relationship also corresponds to the plunger 6. FIG. 7A shows a stopped state of the electromagnetic pump 1. In the supply control mode, when a drive pulse signal is output from the control device 14 to the electromagnetic pump 1, the electromagnetic coil 5 is excited at the ON timing of the drive pulse signal, and a magnetic flux is generated between the magnetic bodies 52 and 53. . As shown in FIGS. 7B and 7C, the plunger 6 receives the magnetic attraction force, rises against the urging force of the urging portion 7, exceeds the bottom dead center, and reaches the top dead center. To reach. During this ascent, the discharge valve 33a separates from the discharge valve seat 33b. At the position of the top dead center, the push-up member 9 does not contact the discharge valve 33a.

  On the other hand, at the off timing of the drive pulse signal, when the magnetic flux from the electromagnetic coil 5 disappears, the plunger 6 is pushed down from the top dead center by the urging force of the urging unit 7 (see FIG. 7D). . At this time, the pressure in the plunger 6 becomes negative due to the stress of the urging portion 7, the discharge valve 33a closes, the suction valve 81 opens, and the fuel Lf is supplied from the suction port 20 into the plunger 6 via the suction joint 2. You. When the plunger 6 reaches the bottom dead center, the stress of the urging portion 7 decreases, the negative pressure in the plunger 6 decreases, and when the pressure becomes equal to or less than the opening pressure of the suction valve 81, the suction valve 81 closes.

  The frequency of the drive pulse signal (on / off timing) and the urging force of the urging unit 7 are set at the timing when the plunger 6 moves down at the off timing to reach the bottom dead center above the stop position, and at the next on timing. And the plunger 6 is adjusted so that the plunger 6 turns upward from the bottom dead center. At the ON timing, the plunger 6 moves upward again, at this time, the discharge valve 33a opens, and the fuel Lf is discharged from the discharge port 30 to the oil feed pipe 13 through the discharge joint 3. Then, at the timing when the plunger 6 becomes the top dead center, the timing is again switched to the off timing, and thereafter, the above-described operation is repeated, so that the plunger moves between the bottom dead center and the top dead center shown in FIGS. 6 reciprocates.

  In the fire extinguishing control mode, the control device 14 outputs, for example, a fire extinguishing pulse signal having a lower excitation level (voltage) and a longer pulse width than the excitation current in the supply control mode. According to this fire-extinguishing pulse signal, the magnetic force generated by the electromagnetic coil 5 is also reduced, so that the plunger 6 moves at a low speed, and the plunger 6 and the push-up member 9 are more slowly moved to the top dead center than in the supply control mode. Move towards. Due to this low-speed movement, the discharge of fuel on the downstream side is almost suppressed, so that no red flame is generated and incomplete combustion can be prevented. Further, since the fire extinguishing pulse signal has a long pulse width and is continuously energized, the plunger 6 and the push-up member 9 continue to move toward the upper limit point beyond the top dead center after reaching the top dead center. Then, as shown in FIG. 7 (e), when the plunger 6 and the push-up member 9 reach the upper limit point, the push-up member 9 pushes up the discharge valve 33a to open the discharge check valve portion 33. State.

  Thus, when the discharge check valve portion 33 is opened, the fuel in the oil feed pipe 13 returns to the fuel tank 12 due to a drop from the liquid level of the fuel tank 12 (see also FIG. 1). However, since the clearance between the cylinder and the plunger is usually small, the return amount of fuel has been limited in the conventional electromagnetic pump. On the other hand, since the electromagnetic pump 1 of the present embodiment has the bypass flow passage 80 for communicating fuel between the inside of the plunger 6 and the suction joint 2, when the discharge valve 33a is opened, the oil supply pipe 13 to the cylinder 4 (plunger 6). Can flow to the suction joint 2 via the bypass path 80 and return to the fuel tank 12 as well as the clearance between the cylinder 4 and the plunger 6 (see also FIG. 2). Therefore, the electromagnetic pump 1 of the present embodiment can stably increase the fuel return amount as compared with the conventional electromagnetic pump. Further, since there is no need to increase the clearance between the cylinder 4 and the plunger 6, the stability of fuel supply during driving can be ensured.

  The fire extinguishing pulse signal is stopped before air enters the discharge joint 3 from the oil feed pipe 13. When the fire extinguishing pulse signal is stopped, the plunger 6 starts moving from the upper limit point toward the bottom dead center rapidly by the spring pressure of the urging portion 7. At this time, the pressure in the cylinder becomes negative instantaneously, and the fuel in the oil supply pipe 13 is further sucked. Then, when the plunger 6 returns to the stop position located further below the bottom dead center, the discharge valve 33a is closed, and thereafter, the return of the fuel is stopped.

  In the present invention, the end of the plunger 6 on the side of the discharge check valve portion 33 is provided with a push-up member 9 which is pushed up to enable the discharge check valve portion 33 to be opened. The present invention is not limited to the above-described embodiment, and various modifications can be made as long as the bypass flow path 80 that allows the fluid to communicate between the inside of the plunger 6 and the suction joint 2 at the time is provided. In the above embodiment, the bypass passage 80 is provided on the suction valve seat 82 side, but may be provided on the suction valve 81 side. However, when the spherical suction valve 81 is used, the position of contact with the suction valve seat 82 may be slightly displaced, and the bypass flow path 80 is connected to the suction valve seat 82 side in stabilizing the return amount of fuel. Is preferably provided. In the above embodiment, an oil fan heater installed indoors is exemplified as the combustion device. However, for example, an oil water heater installed outdoors or a boiler for a hot water room heater may be used. Furthermore, the electromagnetic pump 1 is not limited to a combustion device, and can be employed in various devices that supply liquid using piping. Further, the liquid supplied by the electromagnetic pump 1 may be a liquid other than the liquid fuel such as kerosene.

1 electromagnetic pump 10 oil fan heater (combustion device)
DESCRIPTION OF SYMBOLS 11 Combustion part 12 Fuel tank 13 Oil supply pipe 14 Control device 2 Suction joint 3 Discharge joint 33 Discharge check valve part 4 Cylinder 5 Electromagnetic coil 6 Plunger 7 Energizing part 8 Suction check valve part 81 Suction valve 81a Substantially hemispherical surface 82 Suction valve seat 82e Substantially mortar-shaped surface 83 Suction spring 9 Raised member Lf Fuel (fluid)

Claims (6)

An electromagnetic pump that supplies a fluid in a fuel tank to a combustion unit via an oil supply pipe,
A suction joint forming a fluid suction port, a discharge joint forming a fluid discharge port, a tubular cylinder disposed between the suction joint and the discharge joint, and disposed outside the cylinder. An electromagnetic coil that generates a magnetic force intermittently; a plunger that is disposed inside the cylinder and reciprocates in an axial direction due to an intermittent magnetic force generated by the electromagnetic coil; and balances a magnetic force generated by the electromagnetic coil. An urging portion for reciprocatingly holding the plunger, a suction check valve portion provided inside the plunger for sucking fluid from the suction joint, and a fluid provided inside the discharge joint and sucked by the plunger. And a discharge check valve portion disposed at an end of the plunger on the discharge check valve portion side so as to open the discharge check valve portion. Includes a push-up member that, the,
The suction check valve portion includes a suction valve, a suction valve seat, a suction spring that presses the suction valve toward the suction valve seat, and the suction valve pressed against the suction valve seat by the suction spring. An electromagnetic pump having a bypass passage that sometimes allows fluid to communicate between the inside of the plunger and the suction joint.   The electromagnetic pump according to claim 1, wherein the bypass passage is formed in the suction valve seat.   The electromagnetic pump according to claim 1, wherein the suction valve seat is made of an injection-molded resin. The suction valve has a substantially hemispherical surface facing the suction valve seat,
The suction valve seat has a substantially mortar-shaped surface facing the suction valve,
4. The electromagnetic pump according to claim 1, wherein the bypass flow path is formed by a groove-like path formed in the substantially mortar-shaped surface. 5.   The electromagnetic pump according to any one of claims 1 to 4, wherein the suction valve is made of an inflexible resin.   A combustion device comprising the electromagnetic pump according to any one of claims 1 to 5.