JP2012026430A - Drive control circuit for displacement pump and the displacement pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a displacement pump low in power consumption.SOLUTION: In the displacement pump 1, a diaphragm 12 that varies the volume of a pump chamber 8 is mounted to the moving body 33 of an electromagnetic direct-operated actuator 3. A drive control circuit 70 includes an H bridge circuit 73, a constant current control circuit 76 and a power saving circuit 77. When reciprocating the moving body 33, the H bridge circuit 73 changes directions of an excitation current supplied to a drive coil 38 between the time of outward moving and the time of returning. In each time of outward moving and returning, the constant current control circuit 76 gradually decreases the excitation current from a time when starting the excitation of the drive coil 38, to a first excitation current I1, and to a second excitation current I2 which is lower than the first excitation current I1. The power saving circuit 77 reduces the excitation current from the second excitation current I2 to zero. Thus, power consumption is reduced compared to the case of continuously supplying a constant current to the drive coil 38 while the moving body 33 is reciprocated.

Description

  The present invention relates to a drive control circuit for a positive displacement pump that feeds power to a drive coil of an electromagnetic linear actuator, and a positive displacement pump that drives a movable body for changing the capacity of a pump chamber by an electromagnetic linear actuator. .

  2. Description of the Related Art A positive displacement pump including a movable body such as a diaphragm for changing the volume of a pump chamber and an electromagnetic linear actuator for reciprocating the movable body is known. In the positive displacement pump described in Patent Document 1, the electromagnetic linear actuator is arranged on a cylindrical drive coil, a moving body made of a magnetic material inserted inside the drive coil, and both sides in the axial direction of the drive coil. When power is supplied to the drive coil, the drive coil and the moving body function as an electromagnetic coil, and electromagnetic force generated between the electromagnetic coil and the magnet (axial attractive force or magnetic repulsive force) ) Moves the moving body in the axial direction. The movable body is attached to the movable body, and is displaced by the movement of the movable body to change the volume of the pump chamber.

JP 2005-163547 A

  In order to reduce the power consumption of the positive displacement pump, it is necessary to suppress the power consumption of the drive coil. However, at present, no drive control circuit capable of suppressing the power consumption of the drive coil has been proposed.

  In view of the above problems, an object of the present invention is to provide a drive control circuit for a positive displacement pump and a positive displacement pump capable of reducing power consumption.

In order to solve the above problems, the present invention provides:
The volume of the pump chamber is reduced by the electromagnetic force generated by exciting the moving body of the electromagnetic linear actuator connected to the movable body that changes the volume of the pump chamber by exciting the drive coil of the electromagnetic linear actuator. A drive control circuit for a positive displacement pump that linearly reciprocates between a first position that is a first volume and a second position that is a second volume in which the volume of the pump chamber is larger than the first volume,
A high-level or low-level first pulse signal having a first pulse width equal to or less than ½ of the reciprocating driving cycle in a reciprocating driving cycle in which the movable body is linearly reciprocated between the first position and the second position. A first pulse signal generation circuit that outputs
A second pulse signal generation circuit that outputs a second pulse signal having a high or low level with a second pulse width shorter than the first pulse width when the signal level of the first pulse signal changes;
While the first pulse signal is at one of high level and low level, the direction of the excitation current supplied to the drive coil is maintained in the first direction, and the first pulse signal is at high level and A current direction switching circuit for the exciting current that maintains the direction of the exciting current in a second direction opposite to the first direction while the other is at the low level;
While the second pulse signal is at the signal level output at the change time, the magnitude of the excitation current is maintained at the first current value, and the signal level of the second pulse signal is changed at the change time. A constant current control circuit that maintains the magnitude of the excitation current at the second current value smaller than the first current value while the signal level is different from the output signal level;
It is characterized by having.

  According to the present invention, while the signal level of the first pulse signal output from the first pulse signal generation circuit is one of the high level and the low level, the current direction switching circuit causes the drive coil to Directional excitation current is supplied. Therefore, the moving body can be moved from the first position to the second position or from the second position to the first position by the electromagnetic force generated by the excitation of the drive coil. Further, while the signal level of the first pulse signal is switched to either the high level or the low level, and the signal level is maintained, the excitation current in the second direction is supplied to the drive coil by the current direction switching circuit. Therefore, an electromagnetic force in the opposite direction to that generated while the signal level of the first pulse signal is either the high level or the low level is generated. Therefore, the moving body can be moved from the second position to the first position or from the first position to the second position.

  Here, the second pulse signal generation circuit has a second pulse width high that is shorter than the first pulse width at the time of change when the signal level of the first pulse signal changes (rising time and falling time of the first pulse signal). In addition to outputting the second pulse signal at the level or low level, the constant current control circuit sets the magnitude of the excitation current to the first current value while the second pulse signal is at the signal level output at the time of change. And the magnitude of the excitation current is set to a second current value smaller than the first current value while the signal level of the second pulse signal is different from the signal level outputted at the time of change. maintain. As a result, while moving the moving body from the first position to the second position, or while moving the moving body from the second position to the first position, the current value of the excitation current supplied to the drive coil decreases stepwise. To do. Therefore, the power consumption of the positive displacement pump can be suppressed as compared with a case where an excitation current having a constant magnitude is continuously supplied to the drive coil.

  In the present invention, a third pulse signal having a high level or a low level having a third pulse width that is longer than the second pulse width and shorter than the first pulse width at the time of change when the signal level of the first pulse signal changes. And a third pulse signal generation circuit that outputs a signal level of the excitation current while the third pulse signal has a signal level different from the signal level output at the time of the change. It is desirable to have a power save circuit that makes zero prior to setting. In this way, the third pulse signal output from the third pulse signal generation circuit has a third pulse width longer than the second pulse width and shorter than the first pulse width. While the signal level is different from the signal level output at the time of change, the signal level of the third pulse signal is different from the signal level output at the time of change. Further, when the signal level of the third pulse signal becomes a signal level different from the signal level output at the time of change, the power saving circuit sets the excitation current supplied to the drive coil to zero. As a result, the constant current control circuit decreases the first current value to the second current value while moving the moving body from the first position to the second position or while moving the moving body from the second position to the first position. The magnitude of the excited excitation current can be further reduced to zero by the power saving circuit. Therefore, the effect of suppressing power consumption is high.

  In the present invention, in order to reduce the manufacturing cost of the drive control circuit, it is desirable to use the current direction switching circuit, the constant current control circuit, and the power save circuit that are configured in one IC.

In the present invention, a reference pulse signal generation circuit that outputs a high-level reference pulse signal having a reference pulse width that is ½ of the reference period in a reference period that is ½ of the reciprocating drive period, The first pulse signal generation circuit is a frequency dividing circuit that generates a first pulse signal having a first pulse width that is ½ of the reciprocating drive period based on the reference pulse signal, and the current direction switching circuit includes: The first pulse signal generation circuit and the second pulse signal generation circuit are each composed of a monostable multivibrator circuit, and the rising edge of the reference pulse signal is the change time point. It is desirable. In this way, the manufacturing cost of the drive control circuit can be suppressed.

Next, the positive displacement pump of the present invention is
A movable body that changes the volume of the pump chamber;
An electromagnetic linear motion actuator comprising a moving body connected to the movable body and a drive coil for generating an electromagnetic force for driving the moving body;
Having the above drive control circuit,
The drive control circuit excites the drive coil of the electromagnetic linear actuator, and the movable body has a first position where the volume of the pump chamber becomes the first volume, and the volume of the pump chamber is greater than the first volume. It is characterized by linearly reciprocating between the second position having a larger second volume.

  According to the present invention, during the change of the volume of the pump chamber from the first volume to the second volume or during the change of the volume of the pump chamber from the second volume to the first volume, The current value of the excitation current supplied to the drive coil decreases stepwise. Therefore, the power consumption of the positive displacement pump can be suppressed as compared with the case where a constant excitation current is continuously supplied to the drive coil.

  In the present invention, it is desirable to have a magnet for selectively holding the moving body at the first position or the second position by a magnetic force when the drive coil is not excited. With such a magnet, when the volume of the pump chamber is changed from the first volume to the second volume, the moving body is moved from the first position to the second position against the magnetic attractive force. Therefore, a large electromagnetic force is required to move the moving body away from the first position, and the excitation current at the start of excitation becomes large. However, after the moving body leaves the first position, the magnetic attractive force weakens in inverse proportion to the square of the distance. On the other hand, as the moving body approaches the second position, the magnetic attractive force that holds the moving body at the second position increases in inverse proportion to the square of the distance. Therefore, it becomes easy to move the moving body from the first position to the second position while gradually decreasing the current value of the excitation current supplied to the drive coil. Similarly, when the volume of the pump chamber is changed from the second volume to the first volume, the current value of the excitation current supplied to the drive coil is gradually decreased and moved from the second position to the first position. It becomes easy.

In the present invention, the electromagnetic linear actuator includes an actuator case, a moving body supported by the actuator case so as to be linearly movable, and the moving body so that a magnetic pole surface is parallel to a moving direction of the moving body. A direction orthogonal to the moving direction of the moving body so that the magnet attached to the actuator case, the yoke attached to the actuator case, and the facing surface facing the magnetic pole surface of the magnet with a certain gap are formed. And the drive coil wound around the yoke, wherein the yoke has a first protrusion that minimizes a gap with the magnet in a state where the movable body is located at the first position; A second protrusion that minimizes a gap with the magnet in a state where the movable body is located at the second position. Desirable. In this way, the magnet has a magnetic pole surface parallel to the moving direction of the moving body, and the drive coil faces the magnetic pole surface of the magnet while being wound in a direction perpendicular to the moving direction of the moving body. . Accordingly, when the drive coil is excited, the direction of the excitation current flowing through the drive coil and the direction of the magnetic field of the magnet are orthogonal to generate a Lorentz force. Here, if the Lorentz force is used, a desired thrust can be obtained with a small excitation current compared to the case where the driving coil and the yoke function as electromagnetic coils (electromagnets) to obtain the thrust of the moving body and the movable body. . Further, since the drive coil is wound around the yoke, when the drive coil is excited, the drive coil and the yoke function as an electromagnetic coil (electromagnet), and an electromagnetic attractive force and electromagnetic force are generated between the electromagnetic coil and the magnet. Repulsive force is generated. As a result, the Lorentz force and the electromagnetic attractive force or the electromagnetic repulsive force can be used as the thrust of the movable body, so that the excitation current supplied to the drive coil can be reduced.

  In the present invention, it is preferable that the movable body is a diaphragm, and the volume of the pump chamber is minimum at the first position, and the volume of the pump chamber is maximum at the second position. In this way, the positive displacement pump can be efficiently driven by the electromagnetic linear actuator.

  According to the present invention, the drive control circuit moves the moving body of the electromagnetic linear motion actuator from the first position to the second position to enlarge the pump chamber, or moves the moving body of the electromagnetic linear motion actuator. While moving the pump chamber from the second position to the first position and reducing the pump chamber, the current value of the excitation current supplied to the drive coil of the electromagnetic linear actuator is decreased stepwise. Therefore, the power consumption of the positive displacement pump can be suppressed as compared with a case where an excitation current having a constant magnitude is continuously supplied to the drive coil.

1 is an external perspective view of a positive displacement pump to which the present invention is applied. It is a longitudinal cross-sectional view of the positive displacement pump of FIG. It is a disassembled perspective view of the positive displacement pump of FIG. It is a fragmentary sectional view of the periphery of the electromagnetic linear motion actuator in a state where the moving body is in the raised position. FIG. 5 is a cross-sectional view of the electromagnetic linear motion actuator taken along line AA ′ in FIG. 4. It is a block diagram of a drive control circuit. It is a time chart of each signal and exciting current in a drive control circuit. It is a table | surface which shows the relationship between the setting of a constant current control circuit and a power save circuit, and the signal level input into each circuit. It is explanatory drawing for demonstrating drive control and operation | movement of an electromagnetic linear motion actuator. It is a fragmentary sectional view of the periphery of the electromagnetic linear motion actuator in a state where the moving body is in the lowered position. It is the graph which verified the relationship between the position of a moving body and thrust. It is the graph which verified the relationship between the position of a moving body in the state which considered the reaction force of the diaphragm, and thrust. It is a fragmentary sectional view around a valve chamber. It is a fragmentary sectional view around an active valve in a state where an inflow side channel is closed. It is explanatory drawing for demonstrating the force which acts on the valve body of an active valve. It is a fragmentary sectional view around an active valve in a state where an inflow side channel is opened. It is a time chart which shows the electric current value of the exciting current applied to an electromagnetic linear actuator in a modification. It is explanatory drawing for demonstrating the electromagnetic type linear motion actuator of a modification. It is explanatory drawing for demonstrating the electromagnetic type linear actuator of another modification. It is a longitudinal cross-sectional view of the positive displacement pump of the modification.

  A positive displacement pump to which the present invention is applied will be described with reference to the drawings.

(overall structure)
FIG. 1 is an external perspective view of a positive displacement pump to which the present invention is applied. FIG. 2 is a longitudinal sectional view of the positive displacement pump of FIG. The positive displacement pump 1 includes a pump unit 2 and an electromagnetic direct acting actuator 3 and an active valve 4 arranged in parallel below the pump unit 2. In the following description, a direction in which the electromagnetic linear actuator 3 and the active valve 4 are arranged is referred to as a device width direction, and a direction orthogonal to the device width direction and the vertical direction is referred to as a device front-rear direction. The electromagnetic linear actuator 3 is disposed on the left side in the apparatus width direction, and the active valve 4 is disposed on the right side in the apparatus width direction. An outlet pipe 5 protruding upward is provided on the left side portion of the pump unit 2, and the upper end opening of the outlet pipe 5 is a fluid outlet 5a. An inflow pipe 6 is provided below the active valve 4, and a lower end opening of the inflow pipe 6 serves as a fluid inlet 6a. The electromagnetic linear actuator 3 and the active valve 4 are driven and controlled by a pump drive control circuit 7. The pump drive control circuit 7 includes a drive control circuit 70 for an electromagnetic linear actuator.

  As shown in FIG. 2, a pump chamber 8 is formed inside the pump unit 2. An inflow side channel 9 is formed between the fluid inlet 6 a and the pump chamber 8, and an active valve 4 that opens and closes the inflow side channel 9 is disposed in the inflow side channel 9. An outflow channel 10 is formed between the pump chamber 8 and the fluid outlet 5a. A check valve 11 for preventing a back flow of fluid is disposed in the outflow side channel 10.

  The bottom surface of the pump chamber 8 is defined by a diaphragm (movable body) 12, and the volume of the pump chamber 8 is changed by reciprocating the diaphragm 12 by the electromagnetic linear actuator 3. That is, the positive displacement pump 1 opens the active valve 4 to expand the volume of the pump chamber 8 to suck fluid from the fluid inlet 6a into the pump chamber 8, and closes the active valve 4 to reduce the volume of the pump chamber 8. By doing so, the fluid sucked into the pump chamber 8 is discharged from the fluid outlet 5a.

(Pumping unit)
FIG. 3 is an exploded perspective view of the positive displacement pump 1. The pump unit 2 will be described with reference to FIGS. The pump unit 2 includes an upper housing 21 and a lower housing 22 disposed below the upper housing 21.

  The upper housing 21 is made of PPS (polyphenylene sulfide) resin. The outflow pipe 5 protrudes upward from the left side portion of the upper end surface of the upper housing 21. As shown in FIG. 2, a circular first recess 211 that is recessed upward is provided on the left side of the lower end surface of the upper housing 21. A lower end opening 212 a of the first flow path 212 communicating with the outflow pipe 5 is exposed at the central portion of the ceiling surface of the first recess 211.

  The lower housing 22 is made of PPS (polyphenylene sulfide) resin. A circular upper protrusion 221 that fits into the first recess 211 of the upper housing 21 is formed on the left side of the upper end surface. A circular second recess 222 that is recessed downward is formed in the central portion of the upper protrusion 221. The upper protrusion 221 is fitted in the first recess 211, and the valve chamber 13 is formed coaxially with the outflow pipe 5 by the first recess 211 of the upper housing 21 and the second recess 222 of the lower housing 22. An O-ring 14 is disposed between the outer peripheral surface of the upper protrusion 221 and the inner peripheral surface of the first recess 211. A check valve 11 is configured in the valve chamber 13.

A circular lower protrusion 223 is formed on the lower surface of the left portion of the lower housing 22. A circular third recess 224 that is recessed upward is provided at the center of the lower protrusion 223. The ceiling surface 224a of the third recess 224 is a tapered surface inclined upward toward the central portion, and the lower end opening 225a of the second flow path 225 communicating with the valve chamber 13 is exposed at the central portion. ing. The upper end opening 225 b of the second flow path 225 is exposed at the central portion of the circular bottom surface 13 a of the valve chamber 13. The ceiling surface 224 a and the inner peripheral surface of the third recess 224 define the ceiling surface and the inner peripheral surface of the pump chamber 8. The pump chamber 8, the second flow path 225, the valve chamber 13, the first flow path 212, and the outflow pipe 5 are formed on the same axis, and the second flow path 225, the valve chamber 13, the first flow path 212, the outflow The pipe 5 constitutes the outflow side channel 10.

  A diaphragm 12 that defines the bottom surface of the pump chamber 8 is disposed below the lower protrusion 223. The diaphragm 12 is a rubber elastic body made of EPDM (ethylene propylene diene rubber) or the like, and has a circular planar shape when viewed from above. The diaphragm 12 has a central portion and an outer peripheral edge portion formed thick, and a connecting film portion having a constant thickness that curves so as to bulge upward is provided between the central portion and the outer peripheral edge portion. A connection portion 12 a for connecting the electromagnetic linear actuator 3 is provided at a lower portion of the central portion of the diaphragm 12.

  The electromagnetic linear actuator 3 is attached to the lower housing 22 using the outer peripheral side of the lower protrusion 223. When the electromagnetic linear actuator 3 is attached, the outer peripheral edge portion of the diaphragm 12 is sandwiched between the annular lower end surface of the lower protrusion 223 and the electromagnetic linear actuator 3 and is fixed. Is done.

  A circular fourth recess 226 that is recessed upward is formed on the lower surface of the right side portion of the lower housing 22. The fourth recess 226 includes, from below, a flat large-diameter portion 226a and a small-diameter portion 226b having a smaller diameter than the large-diameter portion. The upper end portion of the active valve 4 is inserted into the fourth recess 226 via the O-ring 15.

  In a state where the active valve 4 is inserted into the fourth recess 226, a space is formed in the upper end portion 226c of the small diameter portion 226b, and there is a space between the upper end portion 226c and the pump chamber 8. A third flow path 227 for communication is formed. The right end opening of the third channel 227 is exposed on the inner peripheral side surface of the upper end portion 226c of the small diameter portion 226b, and the left end opening of the third channel 227 is the ceiling surface of the pump chamber 8 and the lower end of the second channel 225. The part is exposed.

(Electromagnetic linear actuator)
The electromagnetic linear actuator 3 will be described with reference to FIGS. FIG. 4 is a partial cross-sectional view of the periphery of the electromagnetic linear actuator 3 in a state where the moving body is in the raised position. FIG. 5 is a sectional view of the electromagnetic linear actuator 3 taken along the line AA ′ of FIG.

  The electromagnetic linear actuator 3 has a box-shaped upper case 31 having an opening at the lower end and a lower case 32 attached so as to close the opening at the lower end of the upper case 31. Inside the upper case 31 and the lower case 32, a movable body 33 that can move in the vertical direction and a fixed body 34 for moving the movable body 33 are arranged. The upper end portion of the moving body 33 is fixed to the connecting portion 12a of the diaphragm 12. When the moving body 33 reciprocates in the vertical direction, the diaphragm 12 reciprocates in the vertical direction to change the volume of the pump chamber 8. The fixed body 34 includes a first fixed body 35 disposed on the left side of the moving body 33 in the apparatus width direction and a second fixed body 36 disposed on the right side.

As shown in FIG. 3, the moving body 33 includes a rectangular parallelepiped magnet 331 that has a side surface that is parallel to the moving direction of the moving body. The magnet 331 is two-pole magnetized, and magnetic pole surfaces 331a and 331b magnetized to different poles on the left and right sides facing the device width direction. The moving body also includes a magnet holder 332 that holds the outer peripheral surface portion excluding the magnetic pole surfaces 331a and 331b of the magnet 331.

  The magnet holder 332 includes front and rear vertical frame portions 332a that hold the front and rear side surfaces of the magnet 331 from the front and rear direction of the apparatus, an upper frame portion 332b that connects upper end portions of the front and rear vertical frame portions 332a, The lower frame part 332c which has connected the lower end part of the vertical frame part 332a is provided. The front and rear vertical frame portions 332a are provided with guide protrusions 333 that protrude in parallel with the magnetic pole surfaces 331a and 331b, respectively. Each guide protrusion 333 has a rectangular parallelepiped shape and has a predetermined length in the vertical direction. A connection part 334 with the diaphragm 12 is provided on the upper frame part 332b so as to protrude upward. The lower frame portion 332c is provided with a guide shaft 335 protruding downward.

  The first fixed body 35 and the second fixed body 36 include a yoke 37 and a drive coil 38 wound around the yoke 37, respectively. As shown in FIG. 5, the first fixed body 35 is arranged such that the drive coil 38 faces the magnetic pole surface 331a of the moving body 33 with a certain gap therebetween, and the second fixed body 36 is The drive coil 38 is arranged to face the magnetic pole surface 331b with a certain gap.

  Each yoke 37 includes a shaft portion 371 extending in the vertical direction, a first protrusion 372 projecting inward from the upper end portion of the shaft portion 371, and a second projecting inward from the lower end portion of the shaft portion 371. A protrusion 373 is provided.

  Each drive coil 38 is wound around a portion of the yoke 37 between the first protrusion 372 and the second protrusion 373 in a direction orthogonal to the moving direction (vertical direction) of the moving body. As shown in FIG. 5, each drive coil 38 has a rectangular cross-sectional shape by a plane orthogonal to the moving direction of the moving body, and an outer peripheral surface portion 38 a that is one long side of the cross-sectional shape is a magnet. It faces the magnetic pole surfaces 331a and 331b.

  Here, the width dimension of the moving body 33 in the front-rear direction of the magnet 331 is set to be shorter than the width dimension of the outer peripheral surface portion 38 a in the front-rear direction of the apparatus. Further, the length dimension “a” of the moving body 33 in the vertical direction of the magnet 331 is shorter than the length dimension “b” between the first protrusion 372 and the second protrusion 373 in each yoke 37. (See FIG. 4). The length dimension a of the magnet 331 is such that a magnetic attraction force acts between the magnet 331 and the first and second protrusions 372 and 373 when the moving body 33 moves within a predetermined movement range in the vertical direction. There is a region where there is no or a small influence of magnetic attraction force. Specifically, this region is a substantially linear range passing through a displacement of 0 mm and a thrust of 0 mN in the graph shown in FIG.

  Furthermore, as shown in FIG. 3, the lower end portion of each yoke 37 is held by the lower case 32, and the upper end portion of each yoke 37 is supported by a frame-shaped spacer 39. Accordingly, the drive coil 38 of the first fixed body 35 and the drive coil 38 of the second fixed body 36 are maintained at a constant interval along the moving direction of the moving body 33. Further, in the yoke 37, the ends of the first protrusion 372 and the second protrusion 373 on the moving body 33 side are located closer to the moving body 33 than the outer peripheral surface portion 38 a of the drive coil 38, and the shaft portion 371. The protrusion amount of the first protrusion 372 and the protrusion amount of the second protrusion 373 that protrude from the movable body 33 to the side of the moving body 33 are the same.

  The lower case 32 has a flat rectangular parallelepiped shape, and as shown in FIG. 4, a pair of recesses 322 serving as a holding portion of the yoke 37 is formed on the upper end surface. A groove 323 extending in the front-rear direction of the apparatus is formed between the pair of recesses 322 in the apparatus width direction, and a circular through hole 324 is formed in the central portion of the groove 323. The guide shaft 335 of the magnet holder 332 is inserted into the through hole 324. A pair of engaging projections 325 projecting upward are formed outside the pair of recesses 322 in the apparatus width direction.

  As shown in FIG. 3, the upper case 31 includes a rectangular upper plate 311 and four side plates 312 to 315 that extend downward from four edges of the upper plate 311. The upper plate 311 is provided with a rectangular connecting portion 316 that protrudes upward from its upper end surface. A through hole 316a is formed in the central portion of the connecting portion 316, and a stepped portion 316b extending outward is provided at the upper end portion of the through hole 316a. In a state where the electromagnetic linear actuator 3 is attached to the lower housing 22, the lower protruding portion 223 of the lower housing 22 is inserted inside the step portion 316 b, and the annular lower end surface of the lower protruding portion 223 and the step The peripheral edge portion of the diaphragm 12 is sandwiched between the annular end surface of the portion 316b.

  Engaging recesses 317 extending in the vertical direction are formed in the two side plates 312 and 314 extending in parallel in the apparatus width direction. When the upper case 31 is put on the lower case 32, the pair of engaging protrusions 325 engage with the engaging recesses 317 of the side plates 312 and 314 to fix the upper case 31 to the lower case 32.

  A guide groove 318 is formed on the two side plates 313 and 315 that extend in parallel in the front-rear direction of the apparatus, and extends upward at a constant width from the lower end edge of the central portion in the apparatus width direction. The guide groove 318 is located at the center of the first fixed body 35 and the second fixed body 36 in the apparatus width direction. When the upper case 31 is put on the lower case 32, the front and rear guide protrusions 333 of the moving body 33 are inserted into the front and rear guide grooves 318 of the upper case 31, as shown in FIG. 1. Here, the guide protrusion 333 and the guide groove 318 constitute a guide mechanism 40 that guides the moving body 33 in the vertical direction while maintaining a constant gap between each magnetic pole surface 331a, 331b and each drive coil 38. The moving body 33 is guided on the axes of the pump chamber 8, the second flow path 225, the valve chamber 13, the first flow path 212, and the outflow pipe 5 by the guide mechanism 40.

  The upper edge 318 a of each guide groove 318 defines the upper limit of the moving range of the moving body 33. That is, when the moving body 33 attempts to move upward from the ascending position (first position) 33A shown in FIG. 4, each guide protrusion 333 comes into contact with the upper end edge 318a of each guide groove 318 to prevent the movement. To do. At the raised position 33 </ b> A, the upper end surface 331 c of the magnet 331 of the moving body 33 is located below the upper end surface of the first protrusion 372 of each yoke 37. In the state where the moving body 33 is located at the ascending position 33A, the diaphragm 12 sets the volume of the pump chamber 8 to the minimum volume (first volume). It is also possible to configure the movable body 33 so that the movable body 33 is positioned at the raised position 33 </ b> A by the guide protrusions 333 of the movable body 33 coming into contact with the upper edge 318 a of the guide groove 318 of the upper case 31.

  Further, the upper end surface 32 a of the lower case 32 defines a lower limit of the moving range of the moving body 33. That is, when the moving body 33 tries to move downward from the lowered position (second position) 33B (see FIG. 10), each guide protrusion 333 comes into contact with the upper end surface 32a of the lower case 32, and the movement is performed. Stop. In the lowered position 33 </ b> B, the lower end surface 331 d of the magnet 331 of the moving body 33 is positioned above the lower end surface of the second protrusion 373 of each yoke 37. Further, in a state where the moving body 33 is positioned at the lowered position 33B, the diaphragm 12 expands the pump chamber 8 to the maximum volume (second volume). Note that the movable body 33 may be positioned at the lowered position 33 </ b> B by the guide protrusions 333 of the movable body 33 coming into contact with the upper end surface 32 a of the lower case 32.

  Further, while the moving body 33 moves between the raised position 33A and the lowered position 33B, the state where the guide shaft 335 extending downward from the magnet holder 332 is inserted into the through hole 324 is maintained. Thereby, the moving body 33 moves linearly in a state in which the posture is maintained without being inclined with respect to the moving direction.

(Electromagnetic linear actuator drive control circuit)
FIG. 6 is a block diagram of the drive control circuit 70. FIG. 7 is a time chart of each signal and excitation current in the drive control circuit 70. FIG. 8A is a table showing the relationship between the input signal level and the setting of the constant current control circuit, and FIG. 8B is a table showing the relationship between the input signal level and the setting of the power saving circuit. It is.

  The drive control circuit 70 controls the excitation current for exciting the drive coil 38 to move the moving body 33 back and forth linearly between the raised position 33A and the lowered position 33B. The drive control circuit 70 includes a reference pulse signal generation circuit 71, a frequency dividing circuit (first pulse signal generation circuit) 72, an H bridge circuit (current direction switching circuit) 73, a first monostable multivibrator circuit (second pulse signal generation). Circuit) 74, a second monostable multivibrator circuit (third pulse signal generation circuit) 75, a constant current control circuit 76, and a power save circuit 77. The H bridge circuit 73, the constant current control circuit 76, and the power save circuit 77 are configured in one drive IC 78.

  The reference pulse signal generation circuit 71 includes a timer circuit 711 and a waveform shaping circuit 712 that shapes the pulse signal output from the timer circuit 711. As shown in FIG. 7A, the reference pulse signal generation circuit 71 sets the reciprocating driving cycle for moving the moving body 33 linearly between the ascending position 33A and the descending position 33B to 2H. A reference pulse signal S0 having a reference pulse width t0 that is ½ of the reference period H is output at a reference period H of / 2. In this example, the forward excitation start time T0 for starting the excitation for moving the moving body 33 from the raised position 33A to the lowered position 33B, and the excitation for moving the movable body 33 from the lowered position 33B to the raised position 33A. The high-level reference pulse signal S0 with the reference pulse width t0 is output at the backward excitation start time T1 when starting the operation. Therefore, at the forward excitation start time T0 and the backward excitation start time T1, rising edges appear at which the signal level of the reference pulse signal S0 changes from the low level to the high level.

  The frequency dividing circuit 72 generates a first pulse signal S1 having a first pulse width t1 corresponding to the reference period H based on the reference pulse signal S0. As shown in FIG. 7B, the signal level of the first pulse signal S1 alternately changes between a high level and a low level at the rising edge where the reference pulse signal S0 rises. In this example, the signal level of the first pulse signal S1 changes from the low level to the high level at the forward excitation start time T0, and the signal level of the first pulse signal S1 changes from the high level to the low level at the backward excitation start time T1. .

  Inverters 714, 715, and 716 are inserted between the frequency divider circuit 72 and the drive IC 78. The inverters 714, 715, and 716 are for inputting logic signals to the driving IC 78. As shown in FIG. 7C, the logic signal L1 that is the same as the first pulse signal S1 is applied to the IN1 terminal of the driving IC 78. As shown in FIG. 7D, the logic signal L2 obtained by inverting the level of the first pulse signal S1 is input to the IN2 terminal of the driving IC 78.

The H bridge circuit 73 operates based on the logic signals L1 and L2 input to the IN1 terminal and the IN2 terminal, and OUT1 and OUT2 on the output side are connected to the drive coil 38. The H bridge circuit 73 is connected to the drive coil 38 while the logic signal L1 is at high level and the logic signal L2 is at low level (while the signal level of the first pulse signal S1 is at high level). The direction of the excitation current to be supplied is maintained in the first direction D1. Further, while the logic signal L1 is at a low level and the logic signal L2 is at a high level (while the signal level of the first pulse signal S1 is at a low level), excitation supplied to the drive coil 38 is performed. The direction of the current is maintained in the second direction D2 opposite to the first direction D1.
Therefore, in this example, during the period from the forward excitation start time T0 to the backward excitation start time T1, the direction of the excitation current supplied to the drive coil 38 is maintained in the first direction D1, and the backward excitation start time T1. And the next forward excitation start time T0, the direction of the excitation current supplied to the drive coil 38 is maintained in the second direction D2.

  The first monostable multivibrator circuit 74 has an input side connected to the reference pulse signal generation circuit 71 and an output side connected to the ATT2 terminal of the drive IC 78. The ATT2 terminal is an input terminal to the constant current control circuit 76. The first monostable multivibrator circuit 74 has a second pulse width t2 shorter than the first pulse width t1 at the rising edge of the reference pulse signal S0 that appears in the reference period H (when the signal level of the first pulse signal S1 changes). The second pulse signal S2 is output. In this example, as shown in FIG. 7 (e), at the rising edge of the reference pulse signal S0 at the forward excitation start time T0, the second low-level second pulse width t2 is output from the first monostable multivibrator circuit 74. The pulse signal S2 is output, and then the signal level is maintained at a high level. At the rising edge of the reference pulse signal S0 at the backward excitation start time T1, the low-level second pulse signal S2 having the second pulse width t2 is output, and then the signal level is maintained at the high level. The first monostable multivibrator circuit 74 is connected to an RC integration circuit (not shown) including a resistor and a capacitor, and the second pulse width t2 is set by the resistance value of the RC integration circuit.

  The second monostable multivibrator circuit 75 has an input side connected to the reference pulse signal generation circuit 71 and an output side connected to the PS terminal of the drive IC 78. The PS terminal is an input terminal to the power save circuit 77. The second monostable multivibrator circuit 75 has a first pulse width t1 longer than the second pulse width t2 at the rising edge of the reference pulse signal S0 that appears in the reference period H (when the signal level of the first pulse signal S1 changes). A third pulse signal S3 having a shorter third pulse width t3 is output. In this example, as shown in FIG. 7 (f), a high-level third pulse signal S3 having a third pulse width t3 is output at the rising edge of the reference pulse signal S0 at the forward excitation start time T0, and thereafter The signal level is maintained at a low level. Further, at the rising edge of the reference pulse signal S0 at the backward excitation start time T1, the high-level third pulse signal S3 having the third pulse width t3 is output, and then the signal level is maintained at the low level. The second monostable multivibrator circuit 75 is connected to an RC integration circuit (not shown) including a resistor and a capacitor, and the third pulse width t3 is set by the resistance value of the RC integration circuit.

  The constant current control circuit 76 is a current of excitation current supplied to the drive coil 38 via the H bridge circuit 73 based on the signal level input from the ATT1 terminal of the drive IC 78 and the signal level input from the ATT2 terminal. Set the value. As shown in FIG. 8A, in the constant current control circuit 76 of the present example, the current value of the excitation current is set to 100, which is a predetermined current value determined in advance, by a combination of signal levels input from the ATT1 terminal and the ATT2 terminal. %, 80% of the predetermined current value, 50% of the predetermined current value, and 20% of the predetermined current value.

  In this example, as shown in FIG. 6, the signal level input to the ATT1 terminal is set to a high level. Therefore, while the signal level of the second pulse signal S2 input to the ATT2 terminal from the first monostable multivibrator circuit 74 is low, the current value of the excitation current supplied to the drive coil 38 is set in advance. The first current value is maintained at 80% of the predetermined current value. On the other hand, while the signal level of the second pulse signal S2 input to the ATT2 terminal from the first monostable multivibrator circuit 74 is high, the current value of the excitation current supplied to the drive coil 38 is a predetermined current. The second current value is maintained at 20% of the value.

As shown in FIG. 8B, the power save circuit 77 sets the drive IC 78 to the operation mode and inputs it to the PS terminal while the signal level input to the PS terminal of the drive IC 78 is maintained at the high level. The drive IC 78 is set to the standby mode while the signal level to be maintained is kept at the low level. In the operation mode, power can be supplied to the drive coil 38 via the H bridge circuit 73, and in the standby mode, power supply to the drive coil 38 via the H bridge circuit 73 is stopped. In this example, while the signal level of the third pulse signal S3 input from the second monostable multivibrator circuit 75 to the PS terminal is high, the drive IC is set to the operation mode and the drive coil 38 is turned on. Is fed. While the signal level of the third pulse signal S3 input from the second monostable multivibrator circuit 75 to the PS terminal is low, the drive IC is set to the standby mode and power supply to the drive coil 38 is stopped. Is done. That is, the excitation current supplied to the drive coil 38 is set to zero in preference to the setting by the constant current control circuit 76.

  According to the drive control circuit 70, the excitation current supplied to the drive coil 38 is as shown in FIG.

  First, when the high-level reference pulse signal S0 having the reference pulse width t0 corresponding to 1/2 of the reference period H is output from the reference pulse signal generation circuit 71 at the forward excitation start time T0, the frequency divider circuit 72 outputs the reference pulse signal S0. Outputs a high-level first pulse signal S1 having a first pulse width t1 corresponding to the reference period H. Here, while the signal level of the first pulse signal S1 is at a high level, the first logic signal L1 is at a high level, and the excitation current in the first direction D1 is supplied to the drive coil 38 by the H bridge circuit 73. Become so. Since the forward excitation start time T0 is the rising edge of the reference pulse signal S0, the first monostable multivibrator circuit 74 outputs the second pulse signal S2 having a low level with the second pulse width t2. At the same time, the second monostable multivibrator circuit 75 outputs a high-level third pulse signal S3 having a third pulse width t3. As a result, the drive IC 78 is set to the operation mode by the power save circuit 77, and the constant current control circuit 76 causes the drive coil 38 to have a predetermined time corresponding to the second pulse width t2 from the forward excitation start time T0. A first excitation current I1 having a first current value that is 80% of the current value is supplied.

  Next, as shown in FIG. 7E, since the second pulse width t2 of the second pulse signal S2 is shorter than the first pulse width t1 of the first pulse signal S1, the first pulse signal S1 is at a high level. Meanwhile, the signal level of the second pulse signal S2 changes from the low level to the high level. When the signal level of the second pulse signal S2 becomes high level, the constant current control circuit 76 supplies the drive coil 38 with the second excitation current I2 having a second current value smaller than the first current value.

  Thereafter, the signal level of the third pulse signal S3 from the second monostable multivibrator circuit 75 changes from the high level to the low level. That is, as shown in FIG. 7F, the third pulse width t3 is longer than the second pulse width t2 and shorter than the first pulse width t1, so that the signal level of the second pulse signal S2 is changed from low level to high level. The signal level of the third pulse signal S3 changes from the high level to the low level while the first pulse signal S1 is at the high level at the time after the change to the level. When the signal level of the third pulse signal S3 becomes low level, the drive IC 78 is set to the standby mode by the power save circuit 77, and the third excitation current I3 supplied to the drive coil 38 becomes zero.

Next, at the backward excitation start time T1, the signal level of the first pulse signal S1 output from the frequency divider circuit 72 changes from the high level to the low level. The state in which the signal level of the first pulse signal S1 is low continues for a time corresponding to the first pulse width t1. Here, while the signal level of the first pulse signal S1 is at a low level, the second logic signal L2 is at a high level, and an excitation current in the second direction D2 is supplied to the drive coil 38 by the H bridge circuit 73. Become so. Further, since the backward excitation start time T1 is a rising edge of the reference pulse signal S0, the first monostable multivibrator circuit 74 outputs the second pulse signal S2 having a low level with the second pulse width t2. At the same time, the second monostable multivibrator circuit 75 outputs a high-level third pulse signal S3 having a third pulse width t3. As a result, the drive IC 78 is set to the operation mode by the power save circuit 77, and at the same time, the constant current control circuit 76 causes the drive coil 38 to have the return pulse excitation start time T1 after the time corresponding to the second pulse width t2. A first excitation current I1 having a first current value that is 80% of the predetermined current value is supplied.

  After that, as shown in FIG. 7E, the second pulse width t2 of the second pulse signal S2 is shorter than the first pulse width t1 of the first pulse signal S1, so the first pulse signal S1 becomes low level. Meanwhile, the signal level of the second pulse signal S2 changes from the low level to the high level. When the signal level of the second pulse signal S2 becomes high level, the constant current control circuit 76 supplies the drive coil 38 with the second excitation current I2 having a second current value smaller than the first current value.

  Thereafter, the signal level of the third pulse signal S3 from the second monostable multivibrator circuit 75 changes from the high level to the low level. That is, as shown in FIG. 7F, the third pulse width t3 is longer than the second pulse width t2 and shorter than the first pulse width t1, so that the signal level of the second pulse signal S2 is changed from low level to high level. At the time after the change to the level, while the first pulse signal S1 is at the low level, the signal level of the third pulse signal S3 changes from the high level to the low level. When the signal level of the third pulse signal S3 becomes low level, the drive IC 78 is set to the standby mode by the power save circuit 77, and the third excitation current I3 supplied to the drive coil 38 becomes zero.

(Operation of electromagnetic linear actuator)
The drive control and operation of the electromagnetic linear actuator 3 will be described with reference to FIGS. 2, 7, and 9 to 12. FIG. 9 is an explanatory diagram for explaining drive control and operation of the electromagnetic linear actuator, and shows a state in which the moving body 33 is in the raised position 33A. FIG. 10 is a partial cross-sectional view of the periphery of the electromagnetic linear actuator with the moving body 33 in the lowered position 33B. FIG. 11 is a graph in which the relationship between the position of the moving body 33 and the thrust is verified by changing the current value of the excitation current supplied to the drive coil 38. FIG. 11 also shows a graph showing the relationship between the position of the moving body 33 and the reaction force acting on the moving body 33 from the diaphragm 12. FIG. 12 is a graph in which the relationship between the position of the moving body 33 and the thrust is verified by changing the current value of the excitation current supplied to the drive coil 38 in the state where the reaction force of the diaphragm 12 is taken into consideration.

11 and 12, the moving body 33 and the diaphragm 12 are in the positions shown in FIG. 2, and the center of the magnet 331 and the driving coil 38 are moved in the moving direction (vertical direction) of the moving body 33. The center matches. The moving body 33 is located at the raised position 33A shown in FIG. 9 at the position where the displacement amount is 0.6 mm, and the moving body 33 is located at the lowered position 33B shown in FIG. 10 at the position where the displacement is −0.6 mm. In FIG. 11, a graph rising to the right passing through a thrust of 0 gf and a displacement amount of 0 mm is obtained by measuring the thrust at each position (displacement) of the moving body 33 without supplying power to the drive coil 38. is there. In FIG. 11, a downward-sloping graph that passes through a thrust of 0 gf and a displacement of 0 mm is a reaction that acts on the moving body 33 from the diaphragm at each position (displacement) of the moving body 33 when power is not supplied to the drive coil 38. It is a measure of force. The sign of-given to the current value indicates the direction in which the excitation current flows, and corresponds to the first direction D1 in FIG. 7 (g), meaning that the excitation current flows in the direction shown in FIG. Yes. The sign “+” corresponds to the second direction D2 in FIG. 7G, and means that the exciting current flows in the direction opposite to the direction shown in FIG. Further, the sign given to the thrust indicates the direction in which the thrust works, the + sign indicates the upper side, and the-sign indicates the lower side.

  First, when the positive displacement pump is not operating, power is not supplied to the drive coil 38. In this state, the moving body 33 is held at the raised position 33A by the action of the magnetic attractive force F1 between the magnet 331 and the first protrusion 372 of each yoke 37 and the reaction force R1 of the diaphragm 12. The state shown in FIG.

  In this example, when the moving body 33 is in the raised position 33A, as shown in the graph of the current value of 0 mA in FIG. 11, the magnetic attraction force F1 between the magnet 331 and the first protrusion 372 of each yoke 37 is approximately A thrust of 200 mN is generated upward. On the other hand, when the movable body 33 is in the raised position 33A, the diaphragm 12 reduces the volume of the pump chamber 8 to the minimum minimum volume, as shown in FIG. The state is displaced upward. Therefore, the diaphragm 12 generates a reaction force R1 of about 100 mN downward. As a result, as shown in FIG. 12, the moving body 33 has an upward force (about approximately) obtained by subtracting the reaction force R1 of the diaphragm 12 from the magnetic attraction force F1 between the magnet 331 and the first protrusion 372 of each yoke 37. 100mN) and stops at the ascending position 33A.

  Here, when the moving body 33 is moved from the raised position 33 </ b> A to the lowered position 33 </ b> B, the drive control circuit 70 supplies power to the drive coil 38. More specifically, as shown in FIG. 7, the reference pulse signal generation circuit 71 outputs a high-level reference pulse signal S0 having a reference pulse width t0 at the forward excitation start time T0. 72 outputs a high-level first pulse signal S1 having a first pulse width t1. As a result, when the moving body 33 is moved from the raised position 33A to the lowered position 33B, the excitation current in the first direction D1 is supplied to the drive coil 38 by the H bridge circuit 73.

  In addition, since the high-level reference pulse signal S0 is output from the reference pulse signal generation circuit 71 at the forward excitation start time T0, the first monostable multivibrator circuit 74 outputs the second low-level second pulse width t2. The pulse signal S2 is output, and the high-level third pulse signal S3 having the third pulse width t3 is output from the second monostable multivibrator circuit 75. As a result, the drive IC 78 is set in the operation mode by the power save circuit 77, and the constant current control circuit 76 causes the drive coil 38 to have the first current for the time corresponding to the second pulse width t2 from the forward excitation start time T0. A first excitation current I1 of the value is supplied.

  In this example, as shown in FIG. 9, in the magnet 331 of the moving body 33, the left magnetic pole surface 331a is magnetized to the S pole, and the right magnetic pole surface 331b is magnetized to the N pole. Accordingly, in the first direction D1, the excitation current flowing through the winding portion constituting the outer peripheral surface portion 38a facing the magnetic pole surface 331a is applied to the left driving coil 38 facing the magnetic pole surface 331a from the front of the apparatus. An exciting current flows in the direction toward the rear of the apparatus. The excitation current flowing through the winding portion facing the magnetic pole surface 331b is passed through the right drive coil 38 facing the right magnetic pole surface 331b in the direction from the front of the apparatus toward the rear of the apparatus.

Here, since the magnet 331 of the moving body 33 is located on the outer peripheral side of the drive coil 38, the direction of the excitation current flowing through the drive coil 38 by feeding is orthogonal to the direction of the magnetic field by the magnet 331. As a result, when power is supplied to the drive coil 38, the Lorentz force acting between the drive coil 38 and the magnetic field of the magnet 331 acts as a force F2 that moves the moving body 33 downward according to Fleming's left-hand rule. . Further, the drive coil 38 and the yoke 37 function as electromagnetic coils (electromagnets) by supplying power to the drive coil 38 according to Ampere's right-handed screw law. That is, the first fixed body 35 disposed on the left side of the moving body 33 functions as an electromagnetic coil having the S pole on the upper side and the N pole on the lower side. The second fixed body 36 disposed on the right side of the moving body 33 functions as an electromagnetic coil having an N pole on the upper side and an S pole on the lower side. As a result, an electromagnetic repulsive force is generated on the upper side and an electromagnetic attractive force is generated on the lower side between the magnet 331 of the moving body 33 and the first fixed body 35 and the second fixed body 36. . The resultant force F3 of the electromagnetic repulsive force and the attraction force is a thrust for moving the moving body 33 downward together with the force F2 that moves the moving body 33 downward.

  The force F2 for moving the moving body 33 downward and the thrust by the resultant force F3 of the electromagnetic repulsive force and the attractive force appear in FIG. 11 as the difference in thrust between the graph of the current value 0 mA and the graph of each current value. In this example, when an excitation current of −10 mA is supplied to the drive coil 38, a downward thrust of a little less than 100 mN is obtained as shown as the difference between the graph of the current value of 0 mA and the graph of the current value of −10 mA. . Similarly, when an excitation current of −30 mA is supplied to the drive coil 38, a downward thrust exceeding 200 mN is obtained. When an excitation current of −50 mA is supplied to the drive coil 38, a downward thrust exceeding 300 mN is obtained. Note that the sign “−” given to the current value indicates the direction in which the excitation current flows.

  Here, in this example, the moving body 33 is held at the raised position 33A by an upward force of about 100 mN at the raised position 33A. Accordingly, as shown in FIG. 12, while the moving body 33 moves in the first section P1 that is away from the ascending position 33A, as shown in FIG. 11, the drive control circuit 70 has a first current value of −30 mA as the first current value. An exciting current I1 is supplied to the drive coil 38 to generate a downward thrust exceeding 100 mN. Thereby, the moving body 33 moves away from the ascending position 33A and moves downward.

  Next, when the moving body 33 moves away from the ascending position 33A, the magnet 331 moves away from the first protrusion 372 of each yoke 37. Therefore, as shown in the graph of the current value 0 mA in FIG. The magnetic attractive force F1 decreases in inverse proportion to the square of the distance. When the moving body 33 is in the range of displacement 0.2 mm to −0.2 mm, it is hardly affected by the magnetic attraction force F1 between the magnet 331 and the first protrusion 372 of each yoke 37, that is, magnetic. The effective suction force F1 becomes substantially zero.

  Further, when the moving body 33 is at the position of 0 mm displacement, the diaphragm 12 is not displaced in the vertical direction as shown in FIG. Accordingly, as shown in the graph of the reaction force R1 from the diaphragm 12 in FIG. 11, the reaction force R1 does not act from the diaphragm 12 to the moving body 33. Therefore, in the second section P2 in which the moving body 33 passes near the position where the displacement is 0 mm, the moving body 33 can be lowered only by applying a slight thrust to the moving body 33.

  In this example, as shown in FIG. 12, the second excitation current I2 having a second current value smaller than the first excitation current I1 is driven in the second section P2 in which the moving body 33 passes near the position where the displacement is 0 mm. By supplying to the coil 38, a downward thrust is generated, and thereby the moving body 33 is lowered. More specifically, the pulse width t2 of the second pulse signal S2 output from the first monostable multivibrator circuit 74 of the drive control circuit 70 is the time until the moving body 33 reaches the second section P2 from the ascending position 33A. The signal level of the second pulse signal S2 from the first monostable multivibrator circuit 74 is changed from the low level to the high level when the moving body 33 reaches the second section P2. Change. As a result, in the second section P2, the constant current control circuit 76 supplies the second exciting current I2 having the second current value to the drive coil 38. The second current value is -7.5 mA.

Thereafter, when the moving body 33 approaches the lowered position 33B, the magnet 331 approaches the second projecting portion 373, so that the magnetic attractive force F4 between the magnet 331 and the third projecting portion 373 starts working and the attraction thereof. The magnitude of the force F4 increases in inverse proportion to the square of the distance. Moreover, since the suction force F4 is a force that works downward, the suction force F4 is a thrust that moves the moving body 33 downward. Here, when the moving body 33 approaches the lowered position 33B, the diaphragm 12 is displaced downward with respect to the outer peripheral edge as shown in FIG. As shown in the graph of the force R1, the reaction force R1 from the diaphragm 12 to the moving body 33 works upward. However, as shown in FIG. 11, the reaction force R1 acting on the moving body 33 from the diaphragm 12 is smaller than the magnetic attraction force F4 between the magnet 331 and the third protrusion 373, so that the moving body 33 is lowered to the lowered position 33B by the suction force F4.

  In this example, as shown in FIG. 12, in the third section P3 in which the moving body 33 approaches the lowered position 33B, the third exciting current I3 supplied to the drive coil 38 is set to zero, and the moving body is only generated by the attractive force F4. 33 is lowered. More specifically, the pulse width t3 of the third pulse signal S3 output from the second monostable multivibrator circuit 75 of the drive control circuit 70 is the time until the moving body 33 reaches the third section P3 from the ascending position 33A. The signal level of the third pulse signal S3 from the second monostable multivibrator circuit 75 is changed from the high level to the low level when the moving body 33 reaches the third section P3. Change. As a result, in the third section P3, the drive IC 78 is set to the standby mode by the power save circuit 77, and the supply of the excitation current to the drive coil 38 is stopped. That is, the third excitation current I3 in the first direction D1 supplied to the drive coil 38 becomes zero.

  Thereafter, when the movable body 33 reaches the lowered position 33B shown in FIG. 10, the movable body 33 is displaced downward by the magnetic attractive force F4 between the magnet 331 and the second protrusion 373 of each yoke 37 and the movable body 33. The moving body 33 stops because the reaction force R1 from the diaphragm 12 is balanced.

  In the lowered position 33B, the diaphragm 12 expands the volume of the pump chamber 8 to the maximum maximum volume. That is, at the lowered position 33B, when the positive displacement pump is operating and the electromagnetic actuator is operating, power is not supplied to the drive coil 38, so the magnet 331 of the moving body 33 and the first of each yoke 37 The magnetic attractive force F4 and the reaction force R1 from the diaphragm 12 act between the two protrusions 373, and the moving body 33 stops. Further, in this example, when the positive displacement pump is not operating, power is not supplied to the drive coil 38, so the moving body 33 has a magnetic force between the magnet 331 and the second protrusion 373 of each yoke 37. The moving body 33 is held at the lowered position 33B by the action of the attractive suction force F1 and the reaction force R1 of the diaphragm 12.

  Next, when the moving body 33 is moved from the lowered position 33B to the raised position 33A, the same force acts in the opposite direction as the moving body 33 is moved from the raised position 33A to the lowered position 33B. Accordingly, as shown in FIG. 7, the drive control circuit 70 has a first direction D2 in the second direction D2 opposite to the first direction D1 in which the excitation current flows when moving the moving body 33 from the raised position 33A to the lowered position 33B. The third excitation currents I1 to I3 are supplied to the drive coil 38 in this order. Thereby, the moving body 33 generates a magnetic attraction force F1 between the magnet 331 and the first protrusion 372, and a resultant force of the Lorentz force, electromagnetic attraction force and electromagnetic attraction force generated by power feeding. It rises as thrust and reaches the ascending position 33A.

More specifically, as shown in FIG. 7, the first pulse width t1 of the first pulse signal S1 output from the frequency dividing circuit 72 of the drive control circuit 70 is such that the moving body 33 moves from the rising position 33A to the lowering position 33B. The first pulse signal S1 output from the frequency divider circuit 72 is set at the time when the moving body 33 reaches the lowered position 33B, that is, at the time of starting the backward excitation T1. The signal level changes from a high level to a low level. The state in which the signal level of the first pulse signal S1 is low continues for a time corresponding to the first pulse width t1. As a result, when the moving body 33 is moved from the lowered position 33B to the raised position 33A, the excitation current in the second direction D2 opposite to the first direction D1 is supplied to the drive coil 38 by the H bridge circuit 73. Will come to be.

  In addition, since the high level reference pulse signal S0 is output from the reference pulse signal generation circuit 71 at the backward excitation start time T1, the first monostable multivibrator circuit 74 outputs a low level second signal having the second pulse width t2. The pulse signal S2 is output, and the high-level third pulse signal S3 having the third pulse width t3 is output from the second monostable multivibrator circuit 75. As a result, the drive IC 78 is put into an operation mode by the power save circuit 77, and the constant current control circuit 76 causes the drive coil 38 to have the first current value for the time corresponding to the second pulse width t2 from the backward excitation start time T1. A first excitation current I1 is supplied.

  Thereafter, when the signal level of the second pulse signal S2 from the first monostable multivibrator circuit 74 changes from the low level to the high level, the constant current control circuit 76 causes the drive coil 38 to receive the second current value of the second current value. An exciting current I2 is supplied. Thereafter, when the signal level of the third pulse signal S3 from the second monostable multivibrator circuit 75 changes from the high level to the low level, the drive IC 78 is set to the standby mode by the power save circuit 77, and the drive coil 38 is supplied to the drive coil 38. The excitation current supply stops. That is, the third excitation current I3 in the second direction D2 supplied to the drive coil 38 is zero.

  When the moving body 33 is located at the raised position 33A, the magnetic attractive force F1 between the magnet 331 and the first protrusion 372 of each yoke 37, and the reaction force R1 from the diaphragm 12 displaced upward by the moving body 33. And the moving body 33 stops. Further, in this example, when the positive displacement pump is not operating, power is not supplied to the drive coil 38, and the magnet 331 of the moving body 33 and the first protrusions of the yokes 37 are at the raised position 33A. Since the magnetic attractive force F1 is acting between the part 372, the moving body 33 is held at the raised position 33A.

  Here, in this example, as shown in FIG. 12, when the moving body 33 moves from the raised position 33A to the lowered position 33B, the movable body 33 moves from the raised position 33A to a position with a displacement of 0.2 mm. The first exciting current I1 of −30 mA is supplied as the first section P1. The second exciting current I2 of −7.5 mA is supplied as the second section P2 until the moving body 33 moves from the position of the displacement amount of 0.2 mm to the position of the displacement amount −0.4 mm. Power supply is stopped as the third section P3 until the moving body 33 passes the displacement amount −0.4 mm and reaches the lowered position 33B. On the other hand, although description in FIG. 12 is omitted, when the moving body 33 is moved backward from the lowered position 33B to the raised position 33A, the moving body 33 moves from the lowered position 33B to the position where the displacement is −0.2 mm. The first excitation current I1 of 30 mA is supplied as the first section P1, and the second section P2 is 7.5 mA until the moving body 33 moves from the position of the displacement amount −0.2 mm to the position of the displacement amount 0.4 mm. The second excitation current I2 is supplied, and the power supply is stopped as the third section P3 until the moving body 33 passes the displacement amount of 0.4 mm and reaches the rising position 33A.

  Note that the first excitation current I1 of −30 mA is supplied as the first section P1 until the moving body 33 moves from the ascending position 33A or the descending position 33B to the position where the displacement amount is 0.4 mm. The second excitation current I2 of −7.5 mA is supplied from the position of 4 mm to the position of displacement 0 mm as the second section P2, and the power supply is stopped after the moving body 33 passes the displacement 0 mm. Also good. More specifically, by changing the resistance value of the RC integrating circuit externally connected to the first monostable multivibrator circuit 74 and the second monostable multivibrator circuit 75, the second pulse signal second The section in which the first excitation current I1 and the second excitation current I2 are applied may be set as described above by changing the setting of the pulse width t2 and the third pulse width t3 of the third pulse signal. Even in this case, since a thrust force for moving the moving body 33 downward can be obtained, the moving body 33 can be moved from the raised position 33A to the lowered position 33B.

(Check valve)
FIG. 13 is a partial cross-sectional view around the valve chamber 13. As shown in FIG. 13, the check valve 11 includes a valve seat 111 in which an upper end opening 225 b of the second flow path 225 is formed, and the upper end opening by contacting the valve seat 111 from the downstream side in the fluid flow direction. The valve body 112 blocking the 225b, and a biasing member that is inserted between the valve body 112 and the circular ceiling surface 13b of the valve chamber 13 and biases the valve body 112 to the valve seat 111 with a predetermined biasing force. It has. The biasing member is a compression coil spring 113, and the valve seat 111 is a circular bottom surface 13 a of the valve chamber 13.

  The valve body 112 is made of a rubber elastic material such as EPDM (ethylene propylene diene rubber), and has a circular flat plate-shaped closing portion 112a facing the valve seat 111, and downward from the lower surface of the closing portion 112a. And an annular protrusion 112b that protrudes. The annular protrusion 112 b is formed coaxially with the closing portion 112 a and abuts around the upper end opening 225 b of the second flow path 225 in the valve seat 111. The annular protrusion 112b is formed so as to be inclined downward from the outer peripheral edge of the lower surface of the closing portion 112a toward the outside, and is tapered so that the thickness dimension decreases as the distance from the closing portion 112a increases. Yes.

  Further, the valve body 112 includes a positioning portion 112c for positioning the contact position of the compression coil spring 113 on the upper surface of the closing portion 112a located on the side opposite to the valve seat 111. The positioning portion 112c is a cylindrical protrusion having an outer diameter corresponding to the inner diameter of the lower end opening 113a of the compression coil spring 113, and is formed coaxially with the annular protrusion 112b.

  The compression coil spring 113 has an inner diameter that increases upward. The inner diameter of the lower end opening 113a is larger than the opening diameter of the upper end opening 225b of the second flow path 225, and is set to be the same as the outer diameter of the positioning portion 112c. When the check valve 11 is disposed in the valve chamber 13 with the lower end opening 113a of the compression coil spring 113 inserted into the positioning portion 112c, the upper end of the compression coil spring 113 has the second end of the circular ceiling surface 13b of the valve chamber 13. Abutting around the lower end opening 212a of one channel 212, the circular end of the lower end abuts on the upper surface of the closing portion 112a at a position corresponding to the annular projection 112b, and is in a compressed state. As a result, the compression coil spring 113 biases the valve body 112 toward the valve seat 111.

  The check valve 11 has a predetermined pressure equal to or higher than a predetermined urging force by the compression coil spring 113 in the outflow side passage 10 when the volume of the pump chamber 8 is reduced by the diaphragm 12 and the pump chamber 8 becomes high pressure. Is applied in the outflow direction, the upper end opening 225b of the second flow path 225 is opened, and the outflow side flow path 10 is opened. When pressure is applied to the outflow side channel 10 in the direction opposite to the outflow direction, the upper end opening 225b of the second channel 225 is closed and the outflow side channel 10 is closed.

(Active valve)
Next, the active valve 4 will be described in detail with reference to FIGS. FIG. 14 is a partial cross-sectional view of the periphery of the active valve 4 in a state where the inflow side passage 9 is closed. As shown in FIG. 3, the active valve 4 includes a cylindrical body 41, an orifice component 42 extending coaxially upward from the body 41, and an inflow pipe extending coaxially downward from the body 41. 6 is provided.

  The orifice constituting part 42 has a smaller diameter than the body part 41, and the inflow pipe 6 has a smaller diameter than the orifice constituting part 42. The inflow pipe 6 also serves as the inflow pipe 6 of the positive displacement pump 1, and the downstream end is a fluid inlet 6a. As shown in FIG. 4, in the active valve 4, the orifice component 42 is inserted into the small diameter portion 226b of the fourth recess 226 of the lower housing 22, and the upper end portion of the body portion 41 is inserted into the large diameter portion 226a. And attached to the lower housing 22.

The orifice component 42 includes a cylindrical portion 421 and an annular flange portion 422 formed on the outer peripheral side of the lower end of the cylindrical portion 421. The cylindrical portion 421 is formed with an orifice 423 penetrating in the vertical direction along the central axis. A lower end opening 423 a of the orifice 423 is exposed at the lower end surface of the cylindrical portion 421. In addition, an annular recess 424 is formed around the lower end opening 423a of the orifice 423 on the lower end surface of the columnar portion 421, whereby the peripheral edge of the lower end opening 423a of the orifice 423 is an annular protrusion. . The annular protrusion serves as a valve seat 44 of the valve body 43 that opens and closes the lower end opening 423a of the orifice 423.

  The body portion 41 includes a fluid flow path 45 that allows the inflow pipe 6 and the orifice 423 to communicate with each other. The fluid channel 45 is provided coaxially with the orifice 423 and the inflow pipe 6. When the active valve 4 is fixed to the lower housing 22, the inflow side flow path 9 from the pump chamber 8 to the fluid inlet 6a is constituted by the third flow path 227, the upper end portion 226c of the fourth recess 226 and the active valve 4. Is done. A valve element 43 is inserted into the fluid flow path 45 so as to be reciprocally movable in the axial direction. The valve body 43 opens and closes the inflow channel 9 by opening and closing a lower end opening 423a on the fluid channel 45 side of the orifice 423.

  The valve body 43 has a cylindrical shape. The valve element 43 includes a stainless steel pipe 431, three circular magnets 432 arranged in the vertical direction inside the pipe 431, and three disc-shaped magnets arranged between adjacent magnets 432, respectively. The plate 433, two disk-shaped magnetic plates 434 arranged at the upper end and the lower end, a stainless steel lid plate 435 arranged on the upper magnetic plate 434, and the lower magnetic plate 434, respectively. A stainless steel bottom plate 436 is provided. In addition, the thing made from resin can also be used as the pipe 431, the cover board 435, and the baseplate 436. FIG. A circular rubber sheet 437 is attached to the upper surface of the cover plate 435 by a method such as adhesion. Here, the adjacent magnets 432 have the same poles facing the other magnet. More specifically, the upper end magnet 432 is arranged so that the upper side is the S pole and the lower side is the N pole, and the magnet 432 adjacently arranged below the upper side is the N pole and the lower side is the S pole. Further, the magnet 432 arranged below is arranged so that the upper part is an S pole and the lower part is an N pole, and the lower end magnet 432 is an N pole on the upper side and an S pole on the lower side. It is arranged to become. As a result, in the valve body 43, the magnetic lines of force are concentrated at the location where the magnetic plate 433 is located.

  The fluid channel 45 is formed inside a coil bobbin 47 around which a drive coil 46 for driving the valve body 43 is wound. A cylindrical yoke 48 is disposed on the outer peripheral side of the coil bobbin 47.

  The coil bobbin 47 is made of resin, and an annular engagement recess 471 for attaching the orifice component 42 is formed at the upper end portion of the coil bobbin 47. The flange portion 422 of the orifice constituting portion 42 is inserted into and fixed to the engaging recess 471 through the rubber packing 49. An annular holding plate 50 is fitted from above on the outer peripheral side of the columnar portion 421 of the orifice component 42, and the holding plate 50 is fixed to the upper end surface of the coil bobbin 47 and the upper end surface of the yoke 48. The orifice component 42 is fixed to the coil bobbin 47 and the yoke 48. The holding plate 50 is made of a magnetic material.

  In addition, the coil bobbin 47 includes a cylindrical body part 472 extending in the vertical direction and six flange parts 473 that increase in diameter on the outer peripheral surface of the cylindrical body part 472. The five spaces surrounded by the cylindrical body portion 472 and the six flange portions 473 of the coil bobbin 47 are five winding portions around which the drive coil 46 is wound.

The five drive coils 46 wound around the coil bobbin 47 have the winding directions of adjacent drive coils 46 reversed in order to reverse the direction of the excitation current. Also, the five drive coils 46
Are electrically connected in series, for example. Alternatively, a configuration is adopted in which three drive coils 46 located on the inner side in the axial direction are electrically connected in parallel, and the drive coils 46 on both sides in the axial direction are electrically connected in series to those connecting portions. You can also In this example, the vertical dimension of the upper and lower drive coils 46 is ½ of the vertical dimension of the three drive coils 46 positioned therebetween. In the valve body 43, the vertical dimension of the upper and lower magnets 432 is ½ of the vertical dimension of the two magnets 432 therebetween. As a result, when the valve body 43 is in contact with the valve seat 44 and the lower end opening 423a of the orifice 423 is closed, the magnetic plate 433 and the magnetic plate 434 are both positioned at the center of the drive coil 46 in the vertical direction. positioned.

  Here, the outer diameter dimension of the valve body 43 is slightly smaller than the inner diameter dimension of the cylindrical body portion 472 of the coil bobbin 47, and the valve body 43 is inserted into the space inside the cylindrical body portion 472 of the coil bobbin 47. In the state, the fluid flows between the outer peripheral side surface of the valve body 43 and the inner peripheral surface of the cylindrical body portion 472 of the coil bobbin 47.

(Active valve operation)
The operation of the active valve 4 will be described with reference to FIGS. FIG. 15 is an explanatory diagram for explaining the force acting on the valve body 43 of the active valve 4. FIG. 16 is a partial cross-sectional view of the periphery of the active valve 4 in a state where the inflow channel 9 is open. The active valve 4 is driven and controlled by controlling power feeding to the drive coil 46 by a drive control circuit (not shown).

  As shown in FIG. 15, the valve body 43 is held at the closed position 43 </ b> A by the magnetic attractive force F <b> 5 between the magnet 432 of the valve body 43 and the pressing plate 50 in a state where power is not supplied to the drive coil 46. Has been. In the closed position 43A, the valve body 43 has moved to the upper end of the fluid flow path 45 inside the coil bobbin 47, the rubber sheet 437 on the upper end surface of the valve body 43 abuts the valve seat 44, and the lower end opening of the orifice 423 is opened. 423a is blocked. Thereby, the inflow side flow path 9 will be in a closed state. Further, the magnetic plate 433 and the magnetic plate 434 of the valve body 43 are both positioned at the center position of the drive coil 46 in the vertical direction.

  Here, the valve body 43 is located upstream of the valve seat 44 in which the lower end opening 423 a of the orifice 423 is provided in the fluid flow direction, and is a fluid flow path 45 formed coaxially with the orifice 423. It is comprised so that it may move in the distribution direction of the fluid in the inside. For this reason, the fluid pressure (back pressure) of the fluid flowing into the active valve 4 from the fluid inlet 6a exerts the force F6 in the direction of moving the valve body 43 toward the closed position 43A.

  Next, when the inflow channel 9 is opened, power is supplied to the drive coil 46. In the active valve 4, the drive coil 46 wound in a cylindrical shape is disposed on the outer peripheral side of the magnet 432, so that the direction of the excitation current flowing through the drive coil 46 by feeding is orthogonal to the direction of the magnetic field by the magnet 432. As a result, as shown in FIG. 16, when power is supplied to the drive coil 46, the Lorentz force that acts between the magnetic flux of the magnet 432 and the drive coil 46 causes the valve body 43 to move downward from the closed position 43A. Work as F7. Here, at the start of power feeding to the drive coil 46, the magnetic plate 433 and the magnetic plate 434 of the valve element 43 are both positioned at the center position of the drive coil 46 in the vertical direction, and are linked to the drive coil 38. Therefore, a large thrust is generated as the force F7. Accordingly, the valve body 43 resists the magnetic attractive force F5 between the pressure plate 50 and the force F6 caused by the fluid pressure of the fluid flowing into the active valve 4 from the fluid inlet 6a. To the lower open position 43B.

When the valve body 43 moves to the open position 43B, the valve body 43 is separated from the valve seat 44 to the upstream side in the fluid flow direction, and the rubber sheet 437 is separated from the lower end opening 423a of the orifice 423. Thereby, the inflow side flow path 9 will be in an open state. In the open position 43 </ b> B, the valve body 43 reaches the open position where the lower end of the valve body 43 abuts against the protruding portion 474 formed inside the coil bobbin 47 or balances and stops without abutting. In the open position 43B, the fluid that has flowed in from the fluid inlet 6a via the inflow pipe 6 (fluid flow path 45) flows between the outer peripheral surface of the valve body 43 and the cylindrical body 472 of the coil bobbin 47, and the lower end opening 423a. Through the orifice 423 and toward the pump chamber 8.

  Further, when the inflow side channel 9 is closed, the power supply to the drive coil 46 is stopped. When the power supply to the drive coil 46 is stopped, the force F6 caused by the magnetic attraction force F5 between the pressing plate 50 and the fluid pressure of the fluid flowing into the active valve 4 from the fluid inlet 6a shown in FIG. Thus, the valve body 43 moves to the closed position 43A, the valve body 43 comes into contact with the valve seat 44, and returns to the state where the upper end rubber sheet 437 closes the lower end opening 423a of the orifice 423. Accordingly, the inflow channel 9 is closed.

  When the inflow channel 9 is closed, an excitation current in the opposite direction to the case where the valve body 43 is moved from the closed position to the open position may be supplied to the drive coil 46. In this way, the valve body 43 has a Lorentz force generated between the magnet 432 of the valve body 43 and the drive coil 46, a magnetic attractive force F5 between the valve body 43 and the holding plate 50, and a fluid inlet. It moves upward by a force F6 caused by the fluid pressure of the fluid flowing into the active valve 4 from 6a. After the valve body 43 reaches the closed position, if the power supply to the drive coil 46 is stopped, the valve body 43 is held at the closed position 43A.

(Operation of positive displacement pump)
Next, the operation of the positive displacement pump 1 will be described. The electromagnetic linear actuator 3 and the active valve 4 of the positive displacement pump 1 are driven and controlled in synchronization by a pump drive control circuit 7.

  In a state where power is not supplied to the drive coil 38 of the electromagnetic linear actuator 3 and the drive coil 46 of the active valve 4, the valve body 43 of the active valve 4 is held in the closed position 43A as shown in FIG. The active valve 4 closes the inflow side flow path 9. Further, as shown in FIG. 4, the moving body 33 of the electromagnetic linear actuator 3 is held at the raised position 33 </ b> A, and the diaphragm 12 sets the volume of the pump chamber 8 to the minimum minimum volume. The check valve 11 closes the outflow side flow path 10 by closing the upper end opening 225b of the second flow path 225 by the urging force of the compression coil spring 113.

  When the fluid is sucked into the pump chamber 8, the valve element 43 is driven from the closed position 43 </ b> A to the open position 43 </ b> B by supplying power to the drive coil 46 of the active valve 4, and the inflow side flow path 9 is opened. It is said. That is, the active valve 4 is in the state shown in FIG. In parallel with this, power is supplied to the drive coil 46 of the electromagnetic linear actuator 3, whereby the moving body 33 is driven from the raised position 33 </ b> A to the lowered position 33 </ b> B. As a result, as shown in FIG. 10, the volume of the pump chamber 8 expands to the maximum maximum volume.

  When the moving body 33 is lowered and the diaphragm 12 is displaced downward, a negative pressure is generated in the pump chamber 8, so that the fluid is sucked into the pump chamber 8. In a state where negative pressure is generated in the pump chamber 8, the check valve 11 closes the upper end opening 225 b of the second flow path 225 and closes the outflow side flow path 10.

Next, when the fluid is discharged from the pump chamber 8, the power supply to the drive coil 46 of the active valve 4 is stopped. As a result, as shown in FIG. 15, the valve body 43 rises from the open position 43B to the closed position 43A, and the inflow side flow path 9 is closed. In parallel with this,
Power is supplied to the drive coil 46 of the electromagnetic linear actuator 3. That is, an excitation current in the direction opposite to that during fluid suction is supplied to the drive coil 46, and the moving body 33 is driven from the lowered position 33B to the raised position 33A. As a result, as shown in FIGS. 4 and 9, the volume of the pump chamber 8 is reduced to the minimum minimum volume.

  Here, since the pump chamber 8 becomes high pressure when the volume of the pump chamber 8 is reduced, in the outflow side passage 10, a force equal to or greater than a predetermined pressure corresponding to the urging force of the valve body 43 by the compression coil spring 113 is in the outflow direction. It takes. As a result, the fluid moves the valve body 43 in the outflow direction, flows out from the upper end opening 225b of the second flow path 225, and is discharged from the fluid outlet 5a.

  Thereafter, when the positive displacement pump 1 enters a standby state, the valve body 43 of the active valve 4 is held at the closed position 43A, and the active valve 4 closes the inflow side flow path 9. The moving body 33 of the electromagnetic linear actuator 3 is held at the raised position 33A, and the diaphragm 12 sets the volume of the pump chamber 8 to the minimum volume. The check valve 11 closes the outflow side flow path 10 by closing the upper end opening 225 b of the second flow path 225 by the urging force of the compression coil spring 113.

(Function and effect)
According to this example, the drive control circuit 70 that drives and controls the electromagnetic linear actuator 3 in the pump drive control circuit 7 that drives and controls the positive displacement pump 1 moves the moving body 33 of the electromagnetic linear actuator 3 to the raised position 33A. When the pump chamber 8 is expanded by moving from the position to the lowered position 33B, the current value of the excitation current supplied to the drive coil 38 is decreased in three stages. The drive control circuit 70 also sets the current value of the excitation current supplied to the drive coil 38 in three stages when the movable body 33 is moved from the lowered position 33B to the raised position 33A and the pump chamber 8 is reduced. It is decreasing. Accordingly, the power consumption of the positive displacement pump 1 is reduced as compared with the case where a constant current is continuously supplied to the drive coil 38 while the movable body 33 is moved between the raised position 33A and the lowered position 33B. be able to. Further, in this example, since the third excitation current I3 is set to zero, further power saving can be achieved.

  Furthermore, according to this example, the excitation current supplied to the drive coil 38 decreases as the moving body 33 approaches the descending position 33B from the ascending position 33A. The acceleration of the moving body 33 in the vicinity of the lowered position 33B can be suppressed as compared with the case where an excitation current having a constant magnitude is continuously supplied when moving from the lowered position 33B to the lowered position 33B. Accordingly, when the movable body 33 is configured to be positioned at the ascending position 33A by abutting the upper ends 318a of the guide grooves 318 of the upper case 31, the guide protrusions 333 of the movable body 33 are moved. The impact of collision between the body 33 and the upper edge 318a of the guide groove 318 can be suppressed. Similarly, the excitation current supplied to the drive coil 38 becomes smaller as the moving body 33 approaches the raised position 33A from the lowered position 33B, so that the movable body 33 is moved from the lowered position 33B to the raised position 33A. When moving the vehicle 33 toward the front, the acceleration of the moving body 33 in the vicinity of the ascending position 33A can be suppressed. Therefore, in the case where the movable body 33 is positioned at the lowered position 33B by the guide protrusions 333 of the movable body 33 coming into contact with the upper end surface 32a of the lower case 32, the movable body 33 and The impact of the collision of the upper end surface 32a of the lower case 32 can be suppressed. As a result, collision noise can be suppressed and the life of the apparatus can be extended.

Further, according to this example, the fixed body 34 of the electromagnetic linear actuator 3 faces the magnetic pole surfaces 331 a and 331 b of the magnet 331 parallel to the moving direction of the moving body 33 and is orthogonal to the moving direction of the moving body 33. A drive coil 38 wound in the direction is provided. Therefore, when the electromagnetic direct acting actuator 3 is excited by supplying power to the drive coil 38, the direction of the excitation current flowing through the drive coil 38 and the direction of the magnetic field of the magnet 331 are orthogonal to generate a Lorentz force. Further, since the drive coil 38 is wound around the yoke 37, the drive coil 38
When power is supplied to, the drive coil 38 and the yoke 37 function as electromagnetic coils (electromagnets), and an electromagnetic attractive force and an electromagnetic repulsive force are generated between the electromagnetic coil and the magnet 331. In addition, since the first protrusion 372 and the second protrusion 373 are provided at both ends of the yoke 37 extending in the moving direction of the moving body 33, the moving body 33 that moves linearly has any of the protrusions 372 and 373. When approaching, a magnetic attractive force is generated between the magnet 331 and the protrusions 372 and 373. That is, in the positive displacement pump 1, the Lorentz force, the electromagnetic attractive force, the electromagnetic repulsive force, and the magnetic attractive force can be used as the thrust of the diaphragm 12. As a result, a thrust can be obtained by using these three forces. Therefore, according to the positive displacement pump 1, the movable body for changing the volume of the pump chamber 8 can be driven efficiently. Therefore, the excitation current supplied to the drive coil 38 can be suppressed.

  Furthermore, when power supply to the drive coil 38 is stopped and the electromagnetic linear actuator 3 is demagnetized, the moving body 33 is caused by the magnetic attractive force between the magnet 331 and the first protrusion 372 or the second protrusion 373. Is selectively held at the raised position 33A or the lowered position 33B. Accordingly, it is possible to prevent the moving body 33 from moving due to vibrations applied from the outside without supplying power to the drive coil 38. As a result, since the power consumption of the electromagnetic linear actuator 3 in the standby state can be suppressed, the power consumption of the positive displacement pump 1 can be suppressed.

  In this example, the H bridge circuit 73, the constant current control circuit 76, and the power save circuit 77 are configured in one drive IC 78. Therefore, the manufacturing cost of the drive control circuit 70 can be suppressed.

(Modification)
In the above embodiment, the current value of the excitation current applied to the electromagnetic linear actuator is controlled in three stages, but the control of the current value of the excitation current is not limited to this. FIG. 17 is a time chart showing the current value of the exciting current applied to the electromagnetic linear actuator in the modified example.

  As shown in FIG. 17A, in the forward movement or backward movement of the moving body 33, the first excitation current I1 and the second excitation current I2 smaller than the first excitation current from the excitation point of the drive coil 38 in this order. Even if it supplies to, power consumption can be suppressed. Such control can be realized by omitting the second monostable multivibrator circuit 75 and the power save circuit 77 from the drive control circuit 70, for example.

  Further, in the drive IC 78 of this example, the constant current control circuit 76 can set the excitation current in 4 stages, so that the excitation current may be controlled in 3 stages and 4 stages by utilizing this function. . Such control can be realized, for example, by newly providing a monostable multivibrator circuit and inputting a pulse signal having a predetermined pulse width from the monostable multivibrator circuit to the ATT1 terminal. Furthermore, when performing such control, if the power save circuit 77 is used, it is possible to control the excitation current to be reduced in a maximum of five stages as shown in FIG.

  Further, since the electromagnetic direct acting actuator 3 and the active valve 4 of the positive displacement pump 1 are driven and controlled in synchronization by the pump drive control circuit 7, the electromagnetic direct acting actuator 3 and the active valve 4 are synchronized. The reference pulse signal S0 output from the reference pulse signal generation circuit 71 of the drive control circuit 70 or the first pulse signal S1 output from the frequency divider circuit 72 can be used as a signal for obtaining the signal.

Note that the current direction switching circuit is not limited to the H-bridge circuit 73, and may be a circuit that can switch the direction of the excitation current supplied to the drive coil 38 based on the signal level of the first pulse signal S1. Can be adopted.

  In the above example, the first pulse signal S1 is generated from the frequency dividing circuit 72 based on the reference pulse signal S0 output from the reference pulse signal generating circuit 71. Instead of the circuit 72, a pulse generation circuit that generates the first pulse signal S1 may be employed. Further, if the pulse signal generation circuit can generate the second pulse signal S2 having the second pulse width t2 at the time of change when the signal level of the first pulse signal S1 changes between the high level and the low level, The monostable multivibrator circuit 74 can be used instead. Similarly, any pulse signal generation circuit capable of generating the third pulse signal S3 having the third pulse width t3 at the time of change when the signal level of the first pulse signal S1 changes between the high level and the low level. The second monostable multivibrator circuit 75 can be used instead. For example, instead of the frequency divider circuit 72, the first monostable multivibrator circuit 74, and the second monostable multivibrator circuit 75, three independent pulse generators are employed, and the first pulse generator The first pulse signal S1 having the 1 pulse width t1 is output, the second pulse signal S2 having the second pulse width t2 is output from the second pulse generator, and the third pulse width t3 is output from the third pulse generator. The three-pulse signal S3 can be configured to be output, and a synchronization unit that synchronizes the first pulse signal S1, the second pulse signal S2, and the third pulse signal S3 can be configured.

  Further, in the above example, the low-level first pulse signal having the first pulse width t1 is output from the frequency dividing circuit 72 at the forward excitation start time T0. The backward movement may be reversed from the above example.

  Furthermore, in the above example, the first pulse width t1 of the first pulse signal S1 corresponds to the reference period H that is ½ of the reciprocating drive period 2H, but can be shorter. For example, in the above example, if the first pulse width t1 is made shorter than the pulse width corresponding to the reference period H, the time for moving the moving body 33 from the rising position 33A to the lowering position 33B is reduced. It becomes possible to make it shorter than the time to move from 33B to the raising position 33A. In addition, at the time of forward excitation start time T0, a low-level first pulse signal having the first pulse width t1 is output so that the forward movement and the backward movement of the moving body 33 are opposite to the above example. If the first pulse width t1 of the first pulse signal S1 is shortened, the time for moving the moving body 33 from the lowered position 33B to the raised position 33A is reduced, and the moving body 33 is moved from the raised position 33A to the lowered position 33B. It can be made shorter than the time to move to.

(Other embodiments)
Next, even with a positive displacement pump equipped with an electromagnetic linear actuator as shown in FIGS. 18 and 19, the drive control circuit 70 can be used to drive and control the electromagnetic linear actuator. FIG. 18 is an explanatory diagram for explaining a modified electromagnetic linear actuator. In FIG. 18, the arrangement of the moving body 33 and the fixed body 34 is shown by the arrangement of the magnet 331, the yoke 37, and the drive coil 38. In FIG. 19, the magnet 331, the yoke 37, and the drive coil 38 are shown cut along a plane orthogonal to the moving direction of the moving body 33.

  In the above embodiment, the first fixed body 35 and the second fixed body 36 are arranged so as to sandwich the moving body 33 from both sides in the apparatus width direction. However, as shown in FIG. Either one of the body 35 and the second fixed body 36 can be omitted. In other words, the moving body 33 may be linearly driven by one fixed body 34 facing the moving body 33.

In addition, the magnet of the moving body 33 may have a polygonal column shape extending in the vertical direction, and each side surface thereof may be used as a magnetic pole surface, and as many fixed bodies as the number corresponding to the magnetic pole surface may be provided. In this case, as shown in FIG. 18B, for example, the moving body 33 includes a quadrangular prism-shaped magnet 331A. In the magnet 331A, four side surfaces parallel to the moving direction of the moving body 33 are referred to as magnetic pole surfaces 331a, 331a ′, 331b, and 331b ′, respectively. Then, the four fixed bodies 34 are arranged so that each of the magnetic pole surfaces 331a, 331a ′, 331b, 331b ′ and the drive coil 38 face each other. Since a large thrust can be obtained by increasing the number of the fixed bodies 34, the efficiency of the positive displacement pump can be improved.

  Furthermore, as shown in FIG. 18 (c), the magnet 331B of the moving body 33 may be a cylindrical one extending in the vertical direction and polarized and magnetized in the circumferential direction. In this case, as many fixed bodies 34 as the number corresponding to the magnetic pole surfaces 331a, 331a ′, 331b, and 331b ′ formed by the polarization magnetization are provided, and the drive coil 38 is provided at each position of the magnet facing the magnetic pole surface. What is necessary is just to arrange | position each fixing body 34 so that a surface may be opposed.

  FIG. 19 is an explanatory view for explaining an electromagnetic linear actuator of still another modification. In FIG. 19, the arrangement of the moving body 33 and the fixed body 34 is shown by the arrangement of the magnet 331, the yoke 37, and the drive coil 38. In FIG. 19, the magnet 331, the yoke 37, and the drive coil 38 are shown cut along a plane parallel to the moving direction of the moving body 33.

  As shown in FIG. 19A, in this example, a yoke 37 and a drive coil 38 are provided on the moving body 33 side to which the diaphragm 12 is attached, and a magnet 331 is provided on the fixed body 34 side. Also in this example, the magnet 331 is arranged so that the magnetic pole surface 331a is parallel to the moving direction of the moving body 33. Further, a first protrusion 372 and a second protrusion 373 projecting toward the magnet 331 are provided at both ends of the yoke 37, and the drive coil 38 is wound in a direction orthogonal to the moving direction of the moving body 33. In this state, the magnet 331 is disposed so as to face the magnetic pole surface 331a. Further, the length dimension of the magnet 331 in the moving direction of the moving body 33 is set to be shorter than the length dimension of the yoke 37 in the moving direction of the moving body 33. In this example, the moving body 33 is held at the raised position 33A by the magnetic attractive force F4 between the magnet 331 and the second protrusion 373. The moving body 33 is held at the lowered position 33 </ b> B by the magnetic attractive force F <b> 4 between the magnet 331 and the first protrusion 372.

  In the example shown in FIG. 19B, a plurality of fixed bodies 34 including magnets 331 are arranged around a moving body 33 including a yoke 37 and a drive coil 38. In this case, each magnet 331 of each fixed body 34 is disposed so that the same pole faces the outer peripheral surface of the drive coil 38. Further, in this case, the first protrusion 372 and the second protrusion 373 are formed in a disk shape so that the first protrusion 372 and the second protrusion 373 protrude toward the magnets. Since a large thrust can be obtained by increasing the number of the fixed bodies 34, the efficiency of the positive displacement pump can be improved.

Also in the example shown in FIG. 19, when power is supplied to the drive coil 38, the direction of the excitation current flowing through the drive coil 38 and the direction of the magnetic field of the magnet 331 are orthogonal to each other according to Fleming's left-hand rule. Occurs. Further, since the drive coil 38 is wound around the yoke 37 according to Ampere's right-handed screw rule, when power is supplied to the drive coil 38, the drive coil 38 and the yoke 37 function as electromagnetic coils (electromagnets). An electromagnetic attractive force and an electromagnetic repulsive force are generated between the electromagnetic coil and the magnet 331. Further, since the first protrusion 372 and the second protrusion 373 are provided at both ends of the yoke 37 extending in the moving direction of the moving body 33, the moving body 33 that moves linearly has the first and second protrusions. When approaching either 372 or 373, a magnetic attractive force is generated between the magnet 331 and the first and second protrusions 372 and 373. That is, in the positive displacement pump 1, the Lorentz force, the electromagnetic attractive force, the electromagnetic repulsive force, and the magnetic attractive force can be used as the thrust of the diaphragm 12.

(Modification of positive displacement pump)
Next, a modification of the positive displacement pump will be described with reference to FIG. In the above-described embodiment, the active valve 4 that is driven by power feeding is disposed in the inflow side flow path 9, but a passive valve can be disposed. FIG. 20 is a longitudinal sectional view of a positive displacement pump in which a passive valve is arranged in place of the active valve 4. In addition, since the positive displacement pump 1A of this example has the same configuration as the positive displacement pump 1 of the above-described embodiment, the corresponding components are denoted by the same reference numerals and description thereof is omitted.

  In the positive displacement pump 1 </ b> A, the inflow pipe 6 protrudes from the right side portion of the upper end surface of the upper housing 21. The upper end of the inflow pipe 6 is a fluid inlet 6a. A circular fifth concave portion 81 that is recessed upward is provided on the right side portion of the lower end surface of the upper housing 21. A lower end opening 82 a of the fourth flow path 82 communicating with the inflow pipe 6 is exposed at the central portion of the ceiling surface of the fifth recess 81.

  A circular second upper protrusion 83 that fits into the fifth recess 81 of the upper housing 21 is formed on the right side portion of the upper end surface 32 a of the lower housing 22. A circular sixth recess 84 that is recessed downward is formed at the center of the second upper protrusion 83. The second upper protrusion 83 is fitted in the fifth recess 81, and the inflow side valve chamber 85 is formed coaxially with the inflow pipe 6 by the fifth recess 81 of the upper housing 21 and the sixth recess 84 of the lower housing 22. ing. An O-ring 86 is disposed between the outer peripheral surface of the second upper protrusion 83 and the inner peripheral surface of the fifth recess 81. A passive valve 87 is configured in the inflow side valve chamber 85.

  Between the inflow side valve chamber 85 and the valve chamber 13 of the lower housing 22, an in-housing channel 88 is formed. The in-housing flow path 88 includes a first flow path portion 89 extending downward from the inflow side valve chamber 85 and a second flow path extending from the lower end of the first flow path portion 89 in the apparatus width direction toward the valve chamber 13. A portion 90 and a third flow path portion 91 extending upward from the left end of the second flow path portion 90 are provided. The upper end opening 89a of the first flow path portion 89 is exposed at the central portion of the circular bottom surface 85a of the inflow side valve chamber 85, and the upper end opening 91a of the third flow path portion 91 is the central portion of the circular bottom surface 13a of the valve chamber 13. Is exposed. The pump chamber 8 is formed at the central portion of the lower housing 22 in the device width direction, and the central portion of the second flow path portion 90 in the device width direction communicates with the upper end portion of the pump chamber 8. An electromagnetic linear actuator 3 is disposed below the pump chamber 8.

  The passive valve 87 includes a valve seat 92 in which a lower end opening 82a of the fourth flow path 82 is formed, and a valve body 93 that contacts the valve seat 92 from the downstream side in the fluid flow direction and closes the lower end opening 82a. And a biasing member which is inserted between the valve body 93 and the circular bottom surface 85a of the inflow side valve chamber 85 and biases the valve body 93 against the valve seat 92 with a predetermined biasing force. Here, the valve seat 92 is a circular ceiling surface 85 b of the inflow side valve chamber 85, and the urging member is a compression coil spring 94. The valve body 93 has the same configuration as the valve body 112 of the check valve 11, and the compression coil spring 94 has the same configuration as the compression coil spring 113 of the check valve 11. .

  Here, the passive valve 87 has a predetermined pressure equal to or higher than a predetermined urging force by the compression coil spring 94 in the inflow side passage 9 when a negative pressure is generated in the pump chamber 8 due to the expansion of the volume of the pump chamber 8. Is applied in the outflow direction, the lower end opening 82a of the fourth channel 82 is opened. Further, the upper end opening 89a is closed when pressure is applied to the inflow side channel 9 in the direction opposite to the outflow direction.

In addition, as a movable body for changing the volume of the pump chamber 8, a thing other than the diaphragm 12 can be used. For example, like the cylinder, the bottom surface of the pump chamber 8 is moved to the moving body 33.
You may comprise so that it may raise / lower with this movement.

1.1A positive displacement pump 2. Pump unit 3. Electromagnetic linear actuator 4. Active valve 5. Outflow pipe 5a Fluid outlet 6. Inflow pipe 6a Fluid inlet 7. Pump drive Control circuit, 8 ・ Pump chamber, 9 ・ Inlet side channel, 10 ・ Outlet side channel, 11 ・ Check valve, 12 ・ Diaphragm, 12a ・ Connection, 13 ・ Valve chamber, 13a ・ Circular bottom, 13b ・ Circular Ceiling surface, 14/15 / O-ring, 21 / upper housing, 22 / lower housing, 31 / upper case, 32 / lower case, 32a / upper surface, 33 / moving body, 33A / moving body, 33 / moving Body, 33A / rising position, 33B / lowering position, 34 / fixed body, 35 / first fixed body, 36 / second fixed body, 37 / yoke, 38 / drive coil, 38a / outer peripheral surface part, 39 / spacer, 40 · Guide mechanism, 41 · Body , 42-Orifice component, 43-Valve body, 43 A-Closed position, 43 B-Open position, 44-Valve seat, 45-Fluid flow path, 46-Drive coil, 47-Coil bobbin, 48-York, 49-Rubber packing , 50 · holding plate, 70 · drive control circuit, 71 · reference pulse signal generation circuit, 72 · frequency dividing circuit (first pulse signal generation circuit), 73 · H bridge circuit (current direction switching circuit), 74 · first Monostable multivibrator circuit (second pulse signal generation circuit), 75. Second monostable multivibrator circuit (third pulse signal generation circuit), 76. Constant current control circuit, 77. Power save circuit, 78. Drive IC. 81, recessed portion, 82, fourth flow path, 83, second upper protruding portion, 84, recessed portion, 85, inflow side valve chamber, 85a, circular bottom surface, 85b, circular ceiling surface, 86, ring, 87, passive Lub, 88-Housing flow path, 89-First flow path part, 89 a-Upper end opening, 90-Second flow path part, 91-Third flow path part, 92-Valve body, 93-Valve seat, 94- Compression coil spring, 111 / valve seat, 112 / valve element, 112a / closed part, 112b / annular protrusion, 112c / positioning part, 113 / compression coil spring, 113a / lower end opening, 211 / first recess, 212 / first Flow path, 212a, lower end opening, 221, upper protrusion, 222, second recess, 223, lower protrusion, 224, third recess, 224a, ceiling surface, 225, second flow path, 225a, lower end opening, 225b, upper end opening, 226, fourth recess, 226a, large diameter portion, 226b, small diameter portion, 226c, upper end portion, 227, third flow path, 311, upper plate, 312 to 315, side plate, 316, connection portion, 316a, through hole, 316b・ Step, 317 ・ engagement recess, 318 ・ guide groove, 318a ・ upper edge, 322 ・ recess, 323 ・ groove, 324 ・ through hole, 325 ・ engagement projection, 331 ・ 331A ・ 331B, magnet, 331a ・ 331b Magnetic pole surface, 331c, upper end surface, 332, magnet holder, 332, lower frame portion, 332a, vertical frame portion, 332b, upper frame portion, 332c, lower frame portion, 333, guide protrusion, 334, connection portion 335, guide shaft, 371, shaft portion, 372, first protrusion, 373, second protrusion, 421, cylindrical portion, 422, flange portion, 423, orifice, 423a, lower end opening, 424, annular recess 431, pipe, 432, magnet, 433, magnetic plate, 434, magnetic plate, 435, lid plate, 436, bottom plate, 437, rubber sheet, 471, engaging recess, 472, cylindrical barrel 473, flange portion, 474, projecting portion, 711, timer circuit, 712, waveform shaping circuit, 713, frequency divider, 714-716, inverter, D1, first direction, D2, second direction, I1-I3 Excitation current, L1, L2, logic signal, P1 to P3, section, S0, reference pulse signal, S1, first pulse signal, S2, second pulse signal, S3, third pulse signal, T0, forward excitation for excitation Time point, T1, back excitation time, t0, reference pulse width, t1, first pulse width, t2, second pulse width, t3, third pulse width

Claims (8)

The volume of the pump chamber is reduced by the electromagnetic force generated by exciting the moving body of the electromagnetic linear actuator connected to the movable body that changes the volume of the pump chamber by exciting the drive coil of the electromagnetic linear actuator. A drive control circuit for a positive displacement pump that linearly reciprocates between a first position that is a first volume and a second position that is a second volume in which the volume of the pump chamber is larger than the first volume,
A high-level or low-level first pulse signal having a first pulse width equal to or less than ½ of the reciprocating driving cycle in a reciprocating driving cycle in which the movable body is linearly reciprocated between the first position and the second position. A first pulse signal generation circuit that outputs
A second pulse signal generation circuit that outputs a second pulse signal having a high or low level with a second pulse width shorter than the first pulse width when the signal level of the first pulse signal changes;
While the first pulse signal is at one of high level and low level, the direction of the excitation current supplied to the drive coil is maintained in the first direction, and the first pulse signal is at high level and A current direction switching circuit for the exciting current that maintains the direction of the exciting current in a second direction opposite to the first direction while the other is at the low level;
While the second pulse signal is at the signal level output at the change time, the magnitude of the excitation current is maintained at the first current value, and the signal level of the second pulse signal is changed at the change time. A constant current control circuit that maintains the magnitude of the excitation current at the second current value smaller than the first current value while the signal level is different from the output signal level;
A drive control circuit for a positive displacement pump. In claim 1,
A third pulse signal having a third pulse width that is longer than the second pulse width and shorter than the first pulse width is output at the time when the signal level of the first pulse signal changes. A 3-pulse signal generation circuit;
While the third pulse signal has a signal level different from the signal level output at the time of the change, the power saving circuit sets the magnitude of the exciting current to zero in preference to the setting by the constant current control circuit. When,
A drive control circuit for a positive displacement pump. In claim 2,
The drive control circuit for a positive displacement pump, wherein the current direction switching circuit, the constant current control circuit, and the power save circuit are configured in one IC. In claim 3,
A reference pulse signal generation circuit that outputs a high-level reference pulse signal having a reference pulse width that is ½ of the reference period at a reference period that is ½ of the reciprocating drive period;
The first pulse signal generation circuit is a frequency dividing circuit that generates a first pulse signal having a first pulse width that is ½ of the reciprocating drive period based on the reference pulse signal.
The current direction switching circuit is composed of an H-bridge circuit,
Each of the first pulse signal generation circuit and the second pulse signal generation circuit is composed of a monostable multivibrator circuit, and the rising edge of the reference pulse signal is the change time point. Drive control circuit. A movable body that changes the volume of the pump chamber;
An electromagnetic linear motion actuator comprising a moving body connected to the movable body and a drive coil for generating an electromagnetic force for driving the moving body;
A drive control circuit according to any one of claims 1 to 4,
The drive control circuit excites the drive coil of the electromagnetic linear actuator, and the movable body has a first position where the volume of the pump chamber becomes the first volume, and the volume of the pump chamber is greater than the first volume. A positive displacement pump characterized in that it is linearly reciprocated between a second position having a larger second volume. In claim 5,
A positive displacement pump having a magnet for selectively holding the moving body at the first position or the second position by a magnetic force when the drive coil is not excited. In claim 6,
The electromagnetic linear actuator is
An actuator case,
A movable body supported by the actuator case so as to be linearly movable;
The magnet attached to the moving body such that the magnetic pole surface is parallel to the moving direction of the moving body;
A yoke attached to the actuator case;
The drive coil wound around the yoke in a direction perpendicular to the moving direction of the moving body so that a facing surface facing the magnetic pole surface of the magnet with a certain gap is formed;
The yoke includes a first protrusion that minimizes a gap with the magnet when the movable body is located at the first position, and a gap between the yoke and the magnet when the movable body is located at the second position. A second protrusion that minimizes
A positive displacement pump comprising: In claim 7,
The movable body is a diaphragm,
In the first position, the volume of the pump chamber is minimized,
The positive displacement pump, wherein the pump chamber has a maximum volume at the second position.

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