JP5288285B2 - Constant displacement electromagnetic pump - Google Patents

Description

  This invention relates to a supply pump for injecting urea water used for the purpose of SCR (Selective Catalistic Reduction) for reducing nitrogen oxide (Nox) for purifying exhaust gas of an internal combustion engine, etc., and black smoke of a diesel engine. Constant displacement type used for supply pumps that feed fuel to DPF (Diesel Particular Filter) automatic cleaning equipment to collect, reformed water pumps for fuel cells, etc. that are relatively discharged and have high back pressure It relates to an electromagnetic pump.

  The constant displacement electromagnetic pump used for such a purpose is provided with a check valve (backflow prevention valve) at the last flow part in the discharge passage so as not to be affected by the pressure (back pressure) of the external device. For example, it is like patent document 1.

JP 2007-278148 A

  This constant displacement electromagnetic pump is characterized in that the amount of discharge is small in variation with respect to the fluctuation of the discharge back pressure. The back pressure check valve used is opened by the inertial force of the flow of pressurized fluid when the plunger moves forward (pressurization), and closes as the fluid discharge pressure decreases during return.

  When this constant displacement electromagnetic pump is used for an air atomizer, liquid urea or the like and atomizing air are present with pressure in a gas-water mixed state on the downstream side of the back pressure prevention valve. On the other hand, when the electromagnetic plunger moves backward from the top dead center to the bottom dead center, the upstream (upstream) side of the back pressure check valve and the downstream (downstream) side of the discharge valve (mainly in the electromagnetic plunger drive space) The fluid pressure decreases with the time lag of opening the back pressure prevention valve and the discharge valve. At that time, a back pressure exists on the downstream (downstream) side of the back pressure prevention valve. For this reason, the so-called closing from the time when the electromagnetic plunger passes the top dead center until the back pressure valve and the intake valve are closed. During the valve time, the air-water mixed fluid flows back and stays in the pump, and the discharge amount of the pump becomes unstable. In the prior art document 1, since the backflow prevention valve is provided, the performance is improved as compared with the case without the backflow prevention valve, but the inconvenience as described above still remains.

  Also, when the reforming material is relatively LPG, even when it is not an air atomizer, such as a reforming water pump of a fuel cell, the pressure of the reformer is relatively high and the back pressure is high when viewed from the pump. In this case, the quantitativeness of the discharge amount is further deteriorated.

  However, in the constant displacement type electromagnetic pump, the requirement for the accuracy of the constant capacity is severe, and increasing the closing speed of the backflow prevention valve or discharge valve in the last flow part suppresses the backflow of the fluid. When the relationship of upstream hydraulic pressure ≦ downstream hydraulic pressure of the backflow prevention valve is satisfied, the backflow prevention valve may be closed by the spring force of the return spring. It is sufficient to increase the spring constant.

  However, in the actual return spring design, if the spring constant is set high, the spring load inevitably increases and the crack pressure of the backflow prevention valve also increases, and the inertial force (pressure) of the flow of the pressurized fluid is increased. ) Alone cannot be opened.

  Therefore, the present invention aims to increase the return spring constant for the backflow prevention valve and open the backflow prevention valve mechanically (forcedly), aiming at the certainty of closing and opening the valve.

A constant displacement electromagnetic pump according to the present invention includes a suction valve, a discharge valve, a piston, an electromagnetic plunger connected thereto, and an electromagnetic coil that reciprocates the electromagnetic plunger, and gives a constant stroke amount to the plunger. the electromagnetic plunger pump to obtain an stroke per constant output volume, and distribution of the check valve of the spring-loaded back into the discharge passage downstream leading to the discharge hole than the discharge valve, the rod received in the upstream side is provided And a push rod facing the receiving rod is attached, and the backflow prevention valve is mechanically opened against the return spring by the movement of the electromagnetic plunger through the push rod. Claim 1).

  The constant displacement type electromagnetic pump applies a pulse voltage to the lower stator while compressing the return spring while compressing the electromagnetic plunger with the periodic and intermittent magnetomotive force generated from the electromagnetic coil, and the next pulse voltage. When the voltage up to zero is zero, the forward path step in which the electromagnetic plunger is returned by the return spring is repeated.

A piston is integrally fixed to the electromagnetic plunger. The piston has a through hole formed in the central axis direction, a discharge valve provided at the lower end thereof, and a suction valve provided upstream of the discharge valve. ing.
As described above, the reciprocating motion of the electromagnetic plunger causes the piston to reciprocate, and the pump operation is performed by the cooperative operation of the discharge valve and the suction valve.

A push rod for opening the backflow prevention valve is provided at the upper end of the electromagnetic plunger, and the backflow prevention valve is pushed up by the push rod at the top dead center position side of the reciprocating motion of the electromagnetic plunger,・ Forcibly opened.
The backflow prevention valve has a high spring constant and high load, and it is difficult to open it only with the inertia force (pressure) of the discharged fluid. For this reason, it is mechanically and forcibly opened with a push rod. The

  The backflow prevention valve is opened when the electromagnetic plunger is at the top dead center position, and is closed when the electromagnetic plunger is at the bottom dead center position (Claim 2). Then, the ratio between the opening and closing of the backflow prevention valve is controlled by the separation distance at the bottom dead center of the electromagnetic plunger between the tip of the push rod and the backflow prevention valve. 3). That is, the opening and closing of the backflow prevention valve are controlled by a push rod that is driven in accordance with the reciprocation of the electromagnetic plunger, and the ratio of the opening or closing is the ratio between the tip of the push rod and the backflow prevention valve. The valve closing range is increased as the distance increases, and the valve opening range is decreased accordingly.

  Since a pair of upper and lower stoppers are provided in the reciprocating direction of the electromagnetic plunger (Claim 4), the electromagnetic plunger strokes a certain distance between the stoppers, and the constant output amount is can get.

In addition, the backflow prevention valve is characterized in that a cleaning rod is provided on the side of the receiving rod, and this cleaning rod is loosely inserted into the discharge hole (Claim 5 ). As a result, the cleaning rod is also reciprocated repeatedly by opening and closing the backflow prevention valve, cleaning the inside of the discharge hole and preventing clogging, and the difference between the diameters of the cleaning rod and the discharge hole, that is, due to a minute gap It also has a viscous damper effect, and also plays a role of preventing the backflow prevention valve jumping and backflow.

The constant displacement type electromagnetic pump having the above-described configuration according to claim 1, wherein the upper stopper constituting the electromagnetic plunger working chamber of the electromagnetic plunger has a predetermined pressure in the plunger working chamber with respect to an upper stator to which the upper stopper is attached. When the pressure is exceeded, it is moved against the return spring (claim 6 ). While the operation of the electromagnetic pump is stopped, the fluid inside the pump is confined by closing the suction valve, the discharge valve, and the stop valve. From such a structure, when the ambient temperature rises, the pressure inside the pump rises due to the thermal expansion of the fluid inside, and at that time, the pressure interferes with the operation, or in some cases, the liquid leaks. Sometimes. On the other hand, at low temperatures, in the case of an aqueous fluid, icing may occur and damage that cannot be repaired may occur.

  As described above, since this constant displacement electromagnetic pump incorporates a shut-off valve that closes in the direction of fluid flow when operation is stopped, the electromagnetic plunger and the operating chamber are hermetically sealed, and fluid pressure is increased by freezing and thermal expansion of the fluid. Overheats. In order to release this over-pressurizing force, the upper stopper that also serves as the valve seat of the closing valve is moved against the spring to create a gap between the upper stopper that also serves as the closing valve and the valve seat, thereby over-pressurizing force. Is discharged downstream.

As described above, according to the first aspect of the present invention, when the electromagnetic plunger moves backward from the top dead center to the bottom dead center, the backflow prevention valve is closed by the return spring, and the fluid existing after the discharge hole. Backflow due to pressure (back pressure) is prevented. Then, when it further advances to near the top dead center again , the push rod comes into contact with the check valve, and the check valve is pushed up and opened. At this time, the discharge valve is already seated on the valve seat, and no back flow occurs. Then, since the closing time lag of the backflow prevention valve is shortened by being pressed by the return spring at the time of the backward movement process of the electromagnetic plunger and the piston in the next process, a constant discharge amount is ensured.

In the initial stage of the forward movement of the electromagnetic plunger from the bottom dead center to the top dead center, the backflow prevention valve is still closed. Then, when it reaches the top dead center, the push rod moves with the electromagnetic plunger to the upper stator side, so that the push rod pushes up the backflow prevention valve, and the backflow prevention valve moves away from the valve seat and moves to Is discharged from the discharge hole to an external device. At the same time, the discharge valve is closed, the suction valve is opened, and the fluid is sucked into the pump. Next, when the electromagnetic plunger moves backward from the top dead center to the bottom dead center, the check valve is closed, the discharge valve is opened, and the suction valve is closed. ) Is transferred to an electromagnetic plunger working chamber which is a downstream portion of the discharge valve. Since the contact structure between the push rod and the backflow prevention valve is provided on the backflow prevention valve side and abuts the push rod through the support rod, the receiving rod passes through the through hole of the valve seat. As a guide, the backflow prevention valve is prevented from being displaced and the fluid can be discharged smoothly.

  According to the invention of claim 2 and the invention of claim 3, the ratio between the opening and closing of the backflow prevention valve is controlled by the separation distance at the top dead center between the tip of the push rod and the backflow prevention valve. If the separation distance is small, the valve opening rate of the backflow prevention valve is large. Conversely, if the separation distance is large, the valve closing rate is large.

  According to the invention of claim 4, the reciprocating motion of the electromagnetic plunger is restricted by the pair of upper and lower stoppers, and a constant distance is obtained by stroking a certain distance.

According to the fifth aspect of the invention, the cleaning rod provided on the side of the receiving rod of the backflow prevention valve is moved by the movement (opening / closing) of the backflow prevention valve and is deposited on the discharge hole (for example, urea in the case of SCR). Clogging can be prevented by removing the crystal. Further, it has a viscous damper effect due to the difference in the circular diameter between the cleaning rod and the discharge hole, that is, a minute gap, has a backflow prevention effect, and prevents the backflow prevention valve from jumping.

According to the sixth aspect of the present invention, when the electromagnetic pump is stopped, the electromagnetic plunger working chamber is closed not only by the suction valve and the discharge valve but also by the closing valve, so that the inside is sealed and the fluid accumulated in the inside is sealed. If the internal pressure rises abnormally due to an increase in volume due to thermal expansion due to an increase in ambient temperature, the upper stopper moves against the return spring, opens between the closing valve, and escapes from the through hole to the discharge passage. Therefore, damage to the internal equipment can be prevented.

These are the longitudinal cross sections of the Example of this invention. These are enlarged views of the vicinity of the discharge valve. These are the enlarged views of the backflow prevention valve vicinity which shows the relationship between a backflow prevention valve and a push rod, and pushes up the backflow prevention valve by the push rod when it exists in a top dead center position. Indicates the relationship between the backflow prevention valve and the push rod, and the push rod moves backward from the backflow prevention valve when it is at the bottom dead center position, and the backflow prevention valve is closed by the force of the return spring. It is an enlarged view of the vicinity. It is a characteristic diagram which shows the movement of a piston (electromagnetic plunger) and the relationship between opening and closing of a backflow prevention valve.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 to 4 show a constant volume electromagnetic pump 1 used for an air atomizer for urea water injection of SCR that reduces nitrogen oxide (Nox) in exhaust gas of an internal combustion engine, and is made of a magnetic material such as iron. The case 3 is provided with a coil 3 to which a pulse current is applied. The coil 3 is formed by winding an electric wire around a resin bobbin 4 and has a through hole formed through the center of the bobbin 4. Is fitted with a guide pipe 6 made of a non-magnetic material.

An upper stator 8 made of a magnetic material is connected to the upper side of the guide pipe 6 in FIG. 1, and a lower stator 9 made of a magnetic material is connected to the lower side of the guide pipe 6 to constitute an electromagnetic plunger working chamber 10 described below.
The lower stator 9 has a cylinder hole 12 in its axial direction and has a smaller diameter as it goes downward, and a suction hole 13 at its lower end. A portion constituting the suction hole 13 is a suction joint 14.

  The cylinder hole 12 is provided with a suction valve block 15, a non-magnetic cylinder 16, a spacer 17, and finally a rubber or resin lower stopper 18 from the lower end in the axial direction (on the suction passage side). The suction valve block 15 is provided with a suction valve 20 as a check valve, a valve seat 21 on which the suction valve 20 is seated, and a return spring 22 on which the suction valve 20 and the valve seat 21 are seated. In addition, a strainer 23 is provided on the valve seat 21.

  The cylinder 16 is a cylindrical member made of polyetherketone (PEEK) or metal with little ion elution, and a piston 25 described below is slidably inserted therein. The piston 25 is made of a metal material and is a cylindrical body having a through hole 26 in the axial direction at the center. The piston 25 is slidably inserted into the cylinder 16 and is driven by a reciprocating motion of an electromagnetic plunger 35 described below. A discharge valve 27, which is a check valve, is fixed to the lowermost end of the piston 25.

As shown in an enlarged view in FIG. 2, the discharge valve 27 includes a valve seat 28 on which the discharge valve 27 is seated and a return spring 29 on which the discharge valve 27 is seated on the valve seat 28.
Specifically, the return spring 29 and the discharge valve 27 are inserted into the through hole 26, and then the valve seat 28 is press-fitted and attached.

  The pump chamber 31 is composed of a cylinder 16, a suction valve 20 on the lower end side, a piston 25, and a discharge valve 27 mounted at the lowermost end. Is called.

  As described above, the spacer 17 and the lower stopper 18 are arranged on the upper end of the cylinder 16 in FIG. 1, and the lower stopper 18 is fixed to the lower stator 9 to fix the cylinder and to move the electromagnetic plunger 35 below as shown in FIG. And preventing noise and vibration. The lower stopper 18 is made of elastic fluoro rubber or the like.

  The electromagnetic plunger 35 is made of a magnetic material, is disposed in the electromagnetic plunger working chamber 10, and is pressed toward the non-cylinder side by a return spring 36 provided between the cylinders 16 via the spacer 17, and the upper described below It is in contact with the stopper 42. Therefore, the electromagnetic plunger 35 is regulated by the lower stopper 18 and the upper stopper 42 described above and has a predetermined constant stroke A.

A bottomed hole 37 having an opening is formed at the lower end of the electromagnetic plunger 35. The piston 25 is fitted into the bottomed hole 37, and the piston 25 extends downward. Further, at the upper end of the electromagnetic plunger 35, a closing valve 39 and a push rod 40 are projected in the longitudinal direction . The shut-off valve 39 has a ring shape, is fitted around the push rod 40, and abuts an upper stopper 42 that is fitted to the upper stator 8 when no power is supplied.

  The upper stopper 42 is made of nonmagnetic metal, synthetic resin, or the like. A through hole 43 is formed in the central axis direction of the upper stopper 42 and is slidably disposed on the upper stator 8 described above. The upper stator 8 is urged by a return spring 45 and is pressed against a flange portion 46 formed on the upper stator 8 to constitute one surface of the electromagnetic plunger working chamber 10.

  The through-hole 43 formed in the upper stopper 42 functions to release the fluid in the electromagnetic plunger working chamber 10 downstream, and the push rod 40 is loosely inserted into the through-hole 43, and the tip thereof is It protrudes from this through hole 43. The through-hole 43 is closed at the top dead center position of the electromagnetic plunger 35 with the stop valve 39 fitted on the outer periphery of the push rod 40 seated on the upper stopper 42.

As described above, the upper stopper 42 not only obtains a stopper action on the upper side of the electromagnetic plunger 35 but also constitutes one surface of the electromagnetic plunger working chamber 10, so that the internal pressure becomes abnormal when the pump is stopped. When raised, the upper stopper 42 is moved against the return spring 45 to release the pressure downstream. Then, the gap with the shut-off valve 39 is opened, and abnormal pressure flows out from the through hole 43 and is discharged to the discharge side. In this embodiment, the upper stopper 42 is opened when the internal pressure becomes 0.5 Mpa / cm ² .

The electromagnetic plunger working chamber 10 not only reciprocates the electromagnetic plunger 35 as described above, but also the reverse flow described below through the through hole 26 after the discharge valve 27 and the through hole 43 formed in the upper stopper 42. It has a second pump chamber by a discharge passage 59 on the upstream side of the valve 49. That is, the reciprocation of the electromagnetic plunger 35, a second chamber Ri by elongation and contraction of the cylinder 16 of the piston 25 has caused volume change.

Incidentally the second chamber is reduced in volume during forward movement of the solenoid plunger 35, the volume is expanded at the time of backward movement. This volume change action is opposite to the volume change of the pump chamber 31. For this reason, when the electromagnetic plunger returns, the pump chamber 31 is in the compression process, and the fluid in the pump chamber 31 opens the discharge valve 27 and flows out into the electromagnetic plunger working chamber 10 in the suction process. Then, a so-called transfer action of switching from the pump chamber 31 into the electromagnetic plunger working chamber 10 is performed. When the electromagnetic plunger 35 is moved forward, the fluid is discharged from the discharge hole 60 due to the decrease in the volume in the electromagnetic plunger working chamber 10. At this time, the pump chamber 31 is in the suction process.

  The backflow prevention valve 49 is disposed in the discharge passage 59 extending from the through hole 43 to the discharge hole 60, and the backflow prevention valve block 51, the valve seat 52 having the through hole 54, and the backflow prevention valve 49 are connected to the valve seat 52. This is a so-called check valve including a return spring 53 to be seated.

  The backflow prevention valve 49 is provided with a receiving rod 55 protruding on the valve seat side and a cleaning rod 56 protruding on the discharge hole side with the valve interposed therebetween. The receiving rod 55 is loosely inserted into the through hole 54 of the valve seat 52, protrudes from the through hole 54, and faces the tip of the push rod 40. Further, the cleaning rod 56 is loosely inserted into the discharge hole 60 and reciprocated to prevent clogging due to the deposited substance, and the difference in the circular diameter between the cleaning rod and the discharge hole 60, that is, a minute amount. It has a viscous damper effect due to the gap, and also has a backflow prevention action and a backflow prevention valve 49 jumping prevention action.

  The backflow prevention valve 49 is arranged so as to oppose the flow direction of the discharge fluid, and the spring constant of the return spring 53 is set to be large, so that it cannot be opened depending on the inertia force (pressure) of the discharge fluid. Therefore, the check valve 49 is opened by the push rod 40 described above.

  The contact relationship between the receiving rod 55 of the backflow prevention valve 49 and the push rod 40 provided on the electromagnetic plunger 35 will be described from the enlarged drawings of FIGS. 3 and 4. When the electromagnetic plunger 35 is at the top dead center position. When in the state of FIG. 3 at the bottom dead center position, it is in the state of FIG. When the top dead center is reached, the push rod 40 moves upward, contacts the receiving rod 55, pushes the receiving rod 55, and the backflow prevention valve 49 is moved against the return spring 53 via the receiving rod 55. As a result, the backflow prevention valve 49 is pushed up, forcibly separated from the valve seat 52, and the through hole 54 opens. At the bottom dead center, the push rod 40 is lowered, separated from the receiving rod 55, and a gap distance B is generated between the push rod 40 and the push rod 40. Therefore, at this bottom dead center, the backflow prevention valve 49 is seated on the valve seat 52 by the return spring 53, and the backflow of fluid due to the external back pressure is prevented from the discharge hole 60.

  In FIG. 5, a characteristic diagram showing the relationship between the stroke of the electromagnetic plunger 35 and the opening and closing of the check valve 49 is shown. The valve opening range is near the top dead center, and conversely near the bottom dead center, The valve is closed. The valve opening range and the valve closing range are changed by a separation distance B (shown in FIG. 4) at the bottom dead center of the push rod 40 and the receiving rod 55. As the separation distance B increases, the valve closing range is closed. The range is large, and the valve opening range is reduced accordingly. Therefore, the opening / closing characteristics of the check valve can be selected by changing the separation distance B at the bottom dead center.

  When the constant volume electromagnetic pump 1 having the above-described configuration is used for an air atomizer for urea water injection, the pressure pump joint 62 to which pressurized air is supplied at the tip of the discharge hole 60 and the nozzle for urea injection are used. The connected urea injection joint 63 is connected to each other, but the other devices are not shown and will not be described.

  In the constant displacement electromagnetic pump 1, when a pulse current is passed through the coil 3, the coil 3 is excited when it is turned on, the upper stator 8, the lower stator 9 and the electromagnetic plunger 35 are magnetized, and the electromagnetic plunger 35 resists the return spring 36. It moves downward, its lower end abuts on the lower stopper 18, and the downward movement is stopped. The movement of the electromagnetic plunger 35 is transmitted to the piston 25, the piston 25 is driven downward, and the volume of the pump chamber 31 is reduced from the state shown in FIG. 1 (top dead center position) to the bottom dead center position. . As a result, the fluid in the pump chamber 31 is transferred to the downstream side of the discharge valve 27, that is, to the through hole 26. At the same time, the volume of the second pump chamber from the through hole 26 to the backflow prevention valve 49 such as the electromagnetic plunger working chamber 10 is increased because the piston 25 enters the cylinder 16.

  When the pulse current is turned off, the upper stator 8, the lower stator 9, and the electromagnetic plunger 35 are demagnetized, the electromagnetic plunger 35 is moved upward by the return spring 36, the upper end abuts on the upper stopper 42, and the upward movement is stopped. At that time, the piston 25 is also driven upward, and the volume of the second pump chamber of the electromagnetic plunger working chamber 10 is reduced by the volume of the piston 25 that has come out of the cylinder 16, and the push rod 40 comes into contact with the backflow. The prevention valve 49 is opened and the fluid is discharged from the discharge hole 60. At the same time, the discharge valve 27 of the through hole 26 of the piston 25 is closed and the suction valve 20 is opened, so that fluid is sucked into the pump chamber 31 from the suction hole 13.

  When the pulse current is turned on again, the electromagnetic plunger 35 and the piston 25 move downward, and the transfer action is started. Such an action is repeated and a pump action is performed. However, since it is reciprocated with a predetermined stroke A, a constant volume is continuously discharged.

  By adopting such a configuration, constant volume is discharged continuously in response to the applied pulse, but the accuracy of the constant volume is strict, and in order to prevent the capacity from becoming unstable due to backflow, In order to achieve the purpose of closing and opening the backflow prevention valve provided with a passage quickly and reliably, a return spring having a large spring constant is used for the backflow prevention valve 49 as described above. The valve was quickly closed and the valve was opened mechanically through the push rod 40 using the reciprocating motion of the electromagnetic plunger 35. Such a configuration and operation are as described above.

1 Constant Volume Type Electromagnetic Pump 3 Coil 8 Upper Stator 9 Lower Stator 10 Electromagnetic Plunger Operating Chamber 16 Cylinder 18 Lower Stopper 20 Suction Valve 22 Return Spring 25 Piston 26 Through Hole 27 Discharge Valve 31 Pump Chamber 35 Electromagnetic Plunger 36 Return Spring 39 Close Valve 40 Push Rod 42 Upper stopper 43 Through hole 49 Backflow prevention valve 53 Return spring 54 Through hole 55 Receiving rod 56 Cleaning rod 59 Discharge passage 60 Discharge hole

Claims (6)

An electromagnetic plunger having a suction valve, a discharge valve, a piston, an electromagnetic plunger connected thereto, and an electromagnetic coil for reciprocating the electromagnetic plunger, and giving a constant stroke amount to the plunger to obtain a constant output amount per stroke amount in the pump, push the coordinated anti-reflux valve urged by a discharge valve spring back into the discharge passage leading to the discharge hole than, Rutotomoni receive rod provided on the upstream side, facing the receiving rod to said electromagnetic plunger A fixed displacement electromagnetic pump, wherein a rod is attached, and the backflow prevention valve is mechanically opened against a return spring by movement of the electromagnetic plunger through the push rod.   2. The constant displacement electromagnetic pump according to claim 1, wherein the backflow prevention valve is opened when the electromagnetic plunger is at a top dead center position, and is closed when the electromagnetic plunger is at a bottom dead center position.   The ratio of the opening and closing of the backflow prevention valve is controlled by the separation distance at the bottom dead center of the electromagnetic plunger between the tip of the push rod and the backflow prevention valve. Described constant displacement electromagnetic pump.   2. The constant displacement electromagnetic pump according to claim 1, wherein a pair of upper and lower stoppers are provided at the end of the electromagnetic plunger in the reciprocating direction.   2. The constant displacement electromagnetic pump according to claim 1, wherein a cleaning rod is provided on a side of the counter-flow rod of the backflow prevention valve, and the cleaning rod is loosely inserted into the discharge hole. The upper stopper constituting the electromagnetic plunger working chamber of the electromagnetic plunger is moved against the return spring when the pressure in the electromagnetic plunger working chamber exceeds a predetermined pressure with respect to the upper stator to which the electromagnetic plunger is mounted. The constant displacement electromagnetic pump according to claim 4 .

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