JP2020020679A - Volumetric flow rate detector - Google Patents

Abstract

To compensate the pressure drop of a piston-type volumetric flow rate detector.SOLUTION: A permanent magnet 101 is fixed to an end on the upper dead center side of pistons 12_1-12_4 for transporting fluid from an inflow port to an outflow port of a volumetric flow rate detector. Furthermore, an electromagnet 102 corresponding to each of the pistons 12_1-12_4 is disposed at the position facing the permanent magnet 101 at the end on the upper dead center side of the corresponding piston 12_1-12_4. In accordance with the differential pressure between the fluid through the inflow port and the fluid through the outflow port, the electromagnet 102 is driven to apply a force in the moving direction of the piston 12_1-12_4 to the piston 12_1-12_4, thereby compensating the pressure drop of the volumetric flow rate detector.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a positive displacement type flow detector.

As a positive displacement type flow detector, a positive displacement type flow detector using a piston type fluid transfer device 10 shown in FIG. 5 is known (for example, Patent Document 1).
The fluid transfer device 10 shown in FIG. 5 includes four cylinders 11_1-11_4 sequentially oriented in different directions by 90 ° and four pistons 12_1-12_4 reciprocating in the cylinders 11_1-11_4. These four pistons 12_1-12_4 perform reciprocating motions whose phases are sequentially shifted by 90 ° in each cylinder 11_1-11_4, as shown in FIGS.

  A crankshaft 13 is provided at the center of the four cylinders 11_1-11_4. Each piston 12_1-12_4 is connected to a position eccentric from the rotation axis of the crankshaft 13 by each connecting rod 14_1-14_4. . The movement of the pistons 12_1-12_4 is transmitted to the crankshaft 13 via the connecting rods 14_1-14_4, and the crankshaft 13 rotates in the direction of the arrow X due to the movement of the pistons 12_1-12_4.

  The space on the crankshaft 13 side of each of the cylinders 11_1-11_4 communicates with the inlet of the positive displacement type flow detector. Ports P1-P4 of the respective flow paths 15_1-15_4 are connected to positions of the respective cylinders 11_1-11_4 on the outer peripheral side of the fluid transfer device 10. In addition, the flow paths 15_1-15_4 are connected to positions on the inner peripheral side of the adjacent cylinders 11_1-11_4, and are positioned adjacent to the outlets of the flow paths 15_1-15_4 of the adjacent cylinders 11_1-11_4. And ports E1-E4, which are connected to the outlet of the positive displacement type flow detector.

  Fluid flowing into the space on the crankshaft 13 side of each of the cylinders 11_1-11_4 of the fluid transfer device from the inflow port of the positive displacement type flow detector flows into the first cylinder 11 where the piston 12 is located near the top dead center on the outer peripheral side. The flow path between the first cylinder 11 connected to the inner circumference of the first cylinder 11 and the adjacent second cylinder flows into the space closer to the lower dead center (the inner circumference) than the piston 12. Through the passage 15, the gas flows from the port P of the second cylinder of the flow passage 15 into a space closer to the top dead center than the piston 12 of the second cylinder 11.

  Then, when the piston 12 of the second cylinder 11 moves toward the top dead center, the fluid flowing into the second cylinder 11 passes through the port P of the second cylinder 11 and the first cylinder 11 And the second cylinder is pushed back to the flow path 15. At this time, the piston 12 of the first cylinder 11 connects the port E of the first cylinder 11 with the opening on the inner peripheral side of the first cylinder 11 of the flow path 15 between the second cylinder 11 and the second cylinder 11. The closed space to be closed is located at a position formed by the constriction provided at the center of the piston and the first cylinder 11, and the fluid pushed back to the flow path 15 by the piston 12 of the second cylinder 11 causes the closed space. Through the space, it is pushed out from the opening on the inner peripheral side of the first cylinder 11 to the port E of the first cylinder 11 and flows out to the outlet of the positive displacement type flow detector.

As a result, the fluid flowing from the inlet of the positive displacement type flow detector flows in the direction of each arrow (except arrow X) shown in FIGS. 5A to 5D with the movement of each piston 12_1-12_4, A certain amount of fluid flows out to the outlet side per rotation.
Therefore, the flow rate that has passed through the fluid transfer device can be measured from the rotation speed of the crankshaft 13.

  Here, in the positive displacement type flow detector using such a fluid transfer device 10, the positive displacement flow rate detection is performed due to the energy consumed by the movement and friction of the movable mechanical element of the fluid transfer device 10. A pressure loss occurs in which the pressure of the fluid flowing out of the positive displacement flow detector is smaller than the pressure of the fluid flowing into the vessel.

  As a technique for compensating for such a pressure loss, the crankshaft 13 of the fluid transfer device 10 shown in FIG. 5 is used to reduce the pressure of the fluid flowing into the positive displacement flow detector and the pressure of the fluid flowing out of the positive displacement flow detector. A technique of driving with an electric motor so that the differential pressure becomes zero is known (Patent Document 2).

FIG. 6 shows a configuration of a positive displacement type flow detector according to this technique.
As shown in the drawing, the positive displacement type flow detector includes a fluid transfer device 10 shown in FIG. 5, an external shaft 21 connected to a crankshaft 13 of the fluid transfer device 10, and a rotation detecting the rotation speed of the external shaft 21. A sensor 22, an electric motor 23 that rotationally drives the external shaft 21, a differential pressure detecting unit 24, a flow path forming unit 25, and a control device 26 are provided.

  The differential pressure detection unit 24 is provided with an inflow port IN into which a fluid flows, an outflow port OUT through which a fluid flows, a flow path connected to the inflow port IN, and a flow path connected to the outflow port OUT. .

  The differential pressure detecting unit 24 is provided between a flow path connected to the inlet IN and a flow path connected to the outlet OUT, and is configured to control the pressure of the fluid flowing from the inlet IN and the fluid flowing out of the outlet OUT. And a differential pressure sensor 27 that detects a differential pressure that is a difference between the two.

  In addition, the flow path connected to the inlet IN of the differential pressure detection unit 24 passes through the flow path in the flow path forming unit 25 and the space (fluid) on the crankshaft 13 side of each of the cylinders 11_1-11_4 of the fluid transfer device 10. The flow path which is connected to the inflow port of the transfer device 10 and is connected to the outflow port OUT of the differential pressure detecting unit 24 is connected to the ports E1-E4 of the fluid transfer device 10 through the flow path in the flow path forming unit 25. (The outlet of the fluid transfer device 10).

Then, the control device 26 measures the flow rate passing through the positive displacement type flow rate detector based on the rotation speed of the crankshaft 13 detected by the rotation sensor 22.
Further, the control device 26 controls the electric motor 23 according to the differential pressure detected by the differential pressure sensor 27, and controls the electric motor 23 so that the differential pressure detected by the differential pressure sensor becomes zero. A rotation torque is applied to the crankshaft 13 of the fluid transfer device 10 via 21.

JP-A-6-50785 JP 2012-181083 A

The displacement type flow detector which drives the crankshaft 13 of the fluid transfer device 10 by the electric motor 23 shown in FIG. 6 requires a relatively expensive and bulky electric motor.
Further, since it is necessary to extend the crankshaft 13 of the fluid transfer device 10 to the outside of the fluid transfer device 10, it is necessary to provide a seal mechanism so that the fluid does not leak from the fluid transfer device 10. In such cases, leakage of the fluid cannot be completely prevented.

  Instead of directly driving the crankshaft 13 by the electric motor 23, it is also conceivable to transmit rotational torque from the electric motor to the crankshaft 13 housed in the fluid transfer device 10 via a magnetic coupling. In this case, although leakage of the fluid can be prevented, the detection accuracy of the positive displacement type flow rate detector may decrease due to rotational resonance.

An object of the present invention is to compensate for a differential pressure generated in a positive displacement type flow sensor without using an electric motor in a structure in which fluid does not leak without lowering detection accuracy.

  In order to solve the above-described problems, the present invention provides one or more of a reciprocating motion that reciprocates by the force of a fluid flowing from an inflow port and a fluid that flows from the inflow port to the outflow port along with the reciprocating motion. A positive displacement type flow detector having a piston, a magnet fixed to at least one end of the piston, an electromagnet disposed at a position facing the magnet, and controlling the driving of the electromagnet, A magnet-attached piston having a magnet fixed at an end is subjected to a force in a moving direction of the magnet-attached piston due to a magnetic force between the electromagnet and the magnet, by a fluid flowing from an inlet and flowing out of an outlet. And a pressure loss compensation control means for applying a pressure loss compensation so as to eliminate the difference between the pressures of the fluids.

  In such a positive displacement type flow detector, the positive displacement type flow detector is provided with a pressure difference detecting means for detecting a pressure difference between a fluid flowing in from the inlet and a fluid flowing out of the outlet, and the pressure loss compensating means is provided. In the control means, as a force in the moving direction of the magnet-equipped piston, a pressure difference detected by the pressure difference detection means is brought close to 0, and a force corresponding to the pressure difference detected by the pressure difference detection means is a force applied to the magnet. You may comprise so that the drive of the said electromagnet may be controlled so that it may apply to a piston.

  Further, such a positive displacement type flow detector is characterized in that, in the pressure loss compensation control means, when the magnet-equipped piston moves toward top dead center and when the magnet-equipped piston moves toward bottom dead center. When the piston with the magnet is moving toward the top dead center and the piston with the magnet is moving toward the bottom dead center by reversing the direction of the current flowing through the electromagnet. In both cases, a force may be applied to the magnet-equipped piston in a direction of movement of the magnet-equipped piston due to a magnetic force between the electromagnet and the magnet.

  In this case, the positive displacement type flow detector includes a crankshaft, a connecting rod connecting the crankshaft and the magnet-equipped piston, and rotation angle detecting means for detecting a rotation angle of the crankshaft. In the pressure loss compensation control means, the phase of the piston with the magnet is identified from the rotation angle of the crankshaft detected by the rotation angle detection means, and according to the identified phase of the piston with the magnet, the direction of the current flowing through the electromagnet is determined. When the magnet-equipped piston is moving toward top dead center and when the magnet-equipped piston is moving toward bottom dead center, the magnet-equipped piston includes the electromagnet and the magnet. The switching may be performed so that a force directed to the moving direction of the magnet-equipped piston by the magnetic force therebetween is applied.

  In this case, in the pressure loss compensation control means, during the period when the piston with magnet is moving toward top dead center, and during the period when the piston with magnet is moving toward bottom dead center. During at least one of the periods, according to the phase of the identified piston with a magnet, so that the magnitude of the force applied to the piston with the magnet in the direction of movement of the piston with the magnet changes during the period. The magnitude of the current flowing through the electromagnet may be changed.

  The above positive displacement type flow detector is provided with distance calculating means for calculating the distance between the electromagnet and the magnet accompanying the reciprocating motion of the piston with the magnet in the positive displacement flow detector, and the pressure loss compensation control means In the above, the magnitude of the current flowing through the electromagnet is corrected according to the distance calculated by the distance calculation means so that the force applied to the piston with magnet in the moving direction of the piston with magnet becomes a predetermined magnitude. It may be configured as follows.

  The above-described positive displacement type flow detector is characterized in that in the pressure loss compensation control means, the reciprocating motion of the magnet-equipped piston is such that the force applied to the magnet-equipped piston in the moving direction of the magnet-equipped piston has a predetermined magnitude. Accordingly, the magnitude of the current flowing through the electromagnet may be corrected according to the induced electromotive force generated in the electromagnet.

  When the above-mentioned positive displacement type flow detector is provided with a cylinder whose top dead center side is closed by a partition, the magnet-equipped piston reciprocates in the internal space, and the magnet is attached to the magnet-equipped piston. The electromagnet may be fixed to an end on the side of the top dead center, and the electromagnet may be fixed to a position facing the magnet outside the partition wall.

  According to the positive displacement type flow detector as described above, the pressure loss of the positive displacement type flow detector can be compensated without using a relatively expensive and bulky electric motor. In addition, since a seal mechanism with the risk of fluid leakage and a magnetic coupling for transmitting rotational torque are not required, a displacement type flow detector due to fluid leakage or rotational resonance is used to compensate for pressure loss. This does not cause a decrease in the detection accuracy.

  ADVANTAGE OF THE INVENTION According to this invention, without using an electric motor, the pressure loss which generate | occur | produces in a positive displacement type flow detector can be compensated without lowering detection accuracy with the structure which does not generate a fluid leak.

It is a figure showing composition of a fluid transfer device concerning an embodiment of the present invention. It is a figure showing composition of a positive displacement type flow detector concerning an embodiment of the present invention. FIG. 3 is a block diagram illustrating a configuration of a differential pressure compensation control unit of the control device according to the embodiment of the present invention. FIG. 4 is a diagram illustrating a gain table and an F table according to the embodiment of the present invention. FIG. 3 is a diagram illustrating a configuration of a known fluid transfer device. It is a figure showing composition of a publicly known positive displacement type flow detector.

Hereinafter, embodiments of the present invention will be described.
FIG. 1a shows a configuration of a fluid transfer device used in the positive displacement type flow detector according to the present embodiment.
1, the same parts as those of the fluid transfer device 10 shown in FIG. 5 are denoted by the same reference numerals. The fluid transfer device 100 according to the present embodiment has substantially the same configuration as the fluid transfer device 10 shown in FIG. 5, and transfers fluid from the space on the crankshaft 13 side of the cylinders 11_1-11_4 to the ports E1-E4. The mechanism, operation, and fluid path for transferring are basically the same as the mechanism, operation, and fluid path of the fluid transfer device 10 of FIG. 5 described above.

The fluid transfer device 100 according to the present embodiment differs from the fluid transfer device 10 shown in FIG. 5 in the following points.
That is, in the fluid transfer device 100 according to the present embodiment, as shown in FIGS. 1B1 and 1B2, each of the pistons 12_1-12_4 is a permanent magnet fixed to the end on the top dead center side of the piston 12_1-12_4. 101 is provided. 1b1 is a diagram of the end of the piston 12_1-12_4 on the top dead center side viewed in the axial direction of the piston, and FIG. Represents.

  Further, the fluid transfer device 100 according to the present embodiment includes an electromagnet unit 103 in which the electromagnets 102 corresponding to the respective pistons 12_1 to 12_4 are accommodated. Each electromagnet 102 is disposed outside the outer wall of the corresponding piston 12_1-12_4 on the side of the top dead center of the cylinder 11_1-11_4 at a position facing the permanent magnet 101 of the corresponding piston 12_1-12_4.

  Then, the electromagnet 102 of each electromagnet unit 103 can generate a magnetic force in which the direction of the line of magnetic force in the cylinder 11_1-11_4 of the corresponding piston 12_1-12_4 is approximately the direction of the axis of the corresponding piston 12_1-12_4. .

  Hereinafter, for convenience, the front-rear and left-right directions of the fluid transfer device 100 are defined as shown in FIG. 1A, the upper side of the fluid transfer device 100 is defined as a direction from the back of the paper of FIG. The description will be made assuming a direction from the near side to the far side of the paper surface of FIG.

  FIG. 1a schematically shows the configuration of the fluid transfer device 100. FIG. 1c1 shows the appearance of the fluid transfer device 100 as viewed obliquely from above, and FIG. 1c2 shows the appearance of the fluid transfer device 100 as viewed from obliquely below. Is shown. The upper surface of the fluid transfer device 100 is sealed except for the openings of the ports E1 to E4, and the entire lower surface of the fluid transfer device 100 is sealed.

  The cylinder 11_1-11_4 is a cylindrical hole, and the piston 12_1-12_4 has a shape obtained by constricting a central portion of the cylindrical shape. Each of the flow paths 15_1-15_4 is provided at a position approximately at the center in the vertical direction of the cylinder 11_1-11_4, and the port E1-E4 has a hole extending from the opening on the upper surface of the fluid transfer device 100 to the inside of the cylinder 11_1-11_4. It is.

  Next, as shown in FIG. 1d, which schematically shows the configuration of the fluid transfer device 100 as viewed in the front-rear direction, the crankshaft 13 is rotatable about a vertical axis as a rotation axis by a bearing 111 inside the fluid transfer device 100. It is pivoted on.

  At the lower end of the crankshaft 13, a rotation detecting magnet 112 whose permanent magnet changes along the circumferential direction with a permanent magnet is fixed so as to rotate together with the crankshaft 13, as shown in FIG. 1e.

Further, a rotation detecting unit 200 is connected to a lower part of the fluid transfer device 100 as shown in FIG.
The rotation detection unit 200 houses an electronic circuit 202 mounted with a magnetic field detection element 201 such as an MR element or a Hall element, which is arranged at a position facing the rotation detection magnet 112. The rotation angle, angular velocity, rotation speed, and the like of the crankshaft 13 are detected from a change in a magnetic field accompanying rotation of the rotation detection magnet 112 detected by the element 201.

The non-movable part of the fluid transfer device 100 is formed of a non-magnetic material that transmits magnetic force.
Next, FIG. 2 shows a configuration of a positive displacement type flow detector using the fluid transfer device 100 and the rotation detection unit 200.
As shown in the drawing, the positive displacement type flow detector includes a fluid transfer device 100, a rotation detection unit 200, a differential pressure detection unit 300, a flow path forming unit 400, and a control device 500.
The differential pressure detecting unit 300 is provided with an inflow port IN into which a fluid flows, and an outflow port OUT through which a fluid flows out. Further, the differential pressure detecting unit 300 is provided with a flow path connected to the inflow port IN and a flow path connected to the outflow port OUT.

  The differential pressure detection unit 300 is provided between a flow path connected to the inlet IN and a flow path connected to the outlet OUT, and detects a pressure difference between a fluid flowing from the inlet IN and a fluid flowing out of the outlet OUT. Is provided with a differential pressure sensor 301 for detecting the differential pressure.

  The flow path connected to the inflow port IN of the differential pressure detecting unit 300 passes through the flow path in the flow path forming unit 400, and the space (the fluid transfer device) of each of the cylinders 11_1-11_4 of the fluid transfer device 100 on the crankshaft 13 side. 100, and connected to the outflow port OUT of the differential pressure detection unit 300, through the flow path in the flow path forming unit 400, the ports E1-E4 (fluid (The outlet of the transfer device 100).

However, the flow path forming unit 400 may be provided as a unit integrated with the differential pressure detecting unit 300.
Next, the configuration of the control device 500 is shown in FIG.
As illustrated, the control device 500 includes a flow rate measuring unit 501 and a differential pressure compensation control unit 510.
The flow rate measuring unit 501 measures the flow rate that has passed through the positive displacement type flow rate detector based on the rotation speed RS of the crankshaft 13 detected by the electronic circuit 202 of the rotation detection unit 200 and the like.

  The differential pressure compensation control unit 510 controls the differential pressure sensor 301 according to the differential pressure ΔP detected by the differential pressure sensor 301 and the rotation angle θ and the angular velocity AV of the crankshaft 13 detected by the electronic circuit 202 of the rotation detection unit 200. The magnitude and direction of the magnetic force generated by the electromagnet 102 of each electromagnet unit 103 are controlled so that the detected differential pressure ΔP becomes zero.

  Now, the differential pressure compensation controller 510 of the control device 500 includes a gain table 511, a gain calculator 512, a piston phase calculator 513, an F calculator 514, an F table 515, a movement vector calculator 516, and a distance correction gain calculator 517. , An electromotive force correction gain calculator 518, a multiplier 519, and an electromagnet driver 520.

  Here, the gain table 511 is a table that prescribes a relationship between the magnitude of the differential pressure ΔP and the gain G. The gain table 511 defines the relationship between the magnitude of the differential pressure ΔP and the gain G so that the magnitude of the gain G increases as the differential pressure ΔP increases. As the gain table 511, for example, as shown in FIG. An element that defines the relationship between the magnitude of the differential pressure ΔP and the gain G can be used.

The F table 515 is a table that defines a relationship between a preset phase φ of the piston 12_1-12_4 and a force F applied to the piston 12_1-12_4.
The F-table 515 applies a force to move the piston 12_1-12_4 toward the top dead center when the piston 12_1-12_4 is approaching the top dead center, and when the piston 12_1-12_4 is toward the bottom dead center. , The relationship between the phase φ and the force F, which applies a force to move the piston 12_1-12_4 toward the bottom dead center.

That is, as the F table 515, for example, a table that defines the relationship between the phase φ and the force F of the pistons 12_1-12_4 can be used as shown in FIG. 4B.
In the F table 515 of FIG. 4B, the phase φ when the piston 12_1-12_4 is at the bottom dead center is 0, 2π, and the phase φ when the piston 12_1-12_4 is at the top dead center is π. The force in the direction of attraction (the force to move the piston toward the top dead center) is positive, and the force in the direction to move the piston away from the electromagnet 102 (the force to move the piston toward the bottom dead center) is negative. For the phase φ (the phase during which the piston moves from bottom dead center to top dead center), the absolute value of the magnitude is defined as the force in the direction from bottom dead center to top dead center of F1. For a phase φ between π and 2π (a phase during which the piston moves from top dead center to bottom dead center), the absolute value of the magnitude changes from top dead center to bottom dead center of F1. The heading force is defined.

  In addition, as the F table 515, in addition to the F table 515 shown in FIG. 4B, the phase φ is set so as not to apply a force to the piston 12_1-12_4 near the top dead center and the bottom dead center as shown in FIG. 4C. The one that defines the relationship with the force F, the one that defines the relationship with the force F applied to the pistons 12_1-12_4 in a sine wave shape as shown in FIG.

Next, the gain calculation unit 512 obtains a gain G defined for the differential pressure ΔP detected by the differential pressure sensor 301 in the gain table 511.
The piston phase calculation unit 513 calculates the phase φ of each piston 12_1-12_4 from the rotation angle θ of the crankshaft 13 detected by the electronic circuit 202 of the rotation detection unit 200. The phase φ of each piston 12_1-12_4 is shifted by π / 2, and the phase φ of each piston 12_1-12_4 is uniquely determined from the rotation angle θ of the crankshaft 13.

The F calculation unit 514 refers to the F table 515 for each piston 12_1-12_4, and calculates the phase φ of the piston 12_i (the piston 12_i is an arbitrary piston among the pistons 12_1-12_4) calculated by the piston phase calculation unit 513. Is determined with respect to the force F.
Then, the multiplication unit 519 calculates, for each piston 12_1-12_4, a force obtained by multiplying the force F calculated for the piston 12_i by the F calculation unit 514 by the gain G calculated by the gain calculation unit 512.

  Next, the distance correction gain calculator 517 corrects the deviation of the distance between the permanent magnet 101 and the electromagnet 102 of the piston 12_i determined from the phase φ of the piston 12_i from the predetermined reference distance for each piston 12_1-12_4. The gain Gd is calculated.

  That is, the distance between the permanent magnet 101 of the piston 12_i and the electromagnet 102 corresponding to the piston 12_i changes according to the change in the phase φ of the piston 12_i, and the magnitude of the force applied to the piston 12_i depends on the magnitude of the current flowing through the electromagnet 102. Even if the directions are the same, the direction changes with a change in the distance between the permanent magnet 101 of the piston 12_i and the electromagnet 102 corresponding to the piston 12_i.

  Therefore, the distance correction gain calculating unit 517 can cancel the change in force of the pistons 12_1-12_4 due to the change in the distance between the permanent magnet 101 and the electromagnet 102 from the reference distance, and can set the gain Gd of the current of the electromagnet 102. Is calculated.

  Next, the movement vector calculation unit 516 calculates the movement vector of the piston 12_i for each piston 12_1-12_4 from the angular velocity AV of the crankshaft 13 detected by the electronic circuit 202 of the rotation detection unit 200 and the phase φ of the piston 12_i. .

  Then, the electromotive force correction gain calculation unit 518 calculates a gain Gv for each piston 12_1-12_4, which is obtained from the phase φ of the piston 12_i and the movement vector of the piston, for correcting a change in the induced electromotive force generated in the corresponding electromagnet 102. calculate.

  That is, the movement of the permanent magnet 101 of the piston 12_i generates an induced electromotive force in the corresponding electromagnet 102, and the induced electromotive force indicates the position between the permanent magnet 101 of the piston 12_i and the corresponding electromagnet 102 indicated by the phase φ of the piston 12_i. It is determined according to the change of the magnetic force passing through the electromagnet 102 obtained from the relationship and the movement vector of the piston 12_i. Then, even if the magnitude and the direction of the current flowing through the electromagnet 102 are the same, the magnitude of the force applied to the piston 12_i changes with the change in the induced electromotive force.

  Therefore, the electromotive force correction gain calculation unit 518 calculates, for each of the pistons 12_1-12_4, a gain Gv of the current of the electromagnet 102 that can cancel the change in the force caused by the induced electromotive force.

  The electromagnet driving unit 520 calculates the force calculated by the multiplier 519 for the piston 12_i for each piston 12_1-12_4 due to the magnetic interaction between the permanent magnet 101 of the piston 12_i and the magnetic force generated by the electromagnet 102 corresponding to the piston 12_i. The magnitude and direction of the magnetic force generated by the electromagnet 102 corresponding to the piston 12_i, that is, the magnitude and direction of the current flowing through the electromagnet 102, with reference to the gain Gd and the gain Gv obtained for the piston 12_i so as to be added to the piston 12_i. Control.

  When the current flowing through the electromagnet 102 increases, the force applied to the piston 12_i increases, and the direction of the current matches the polarity of the magnetic pole on the piston side of the electromagnet 102 with the polarity of the magnetic pole on the top dead center side of the permanent magnet 101 of the piston. When the electromagnet 102 and the permanent magnet 101 repel each other, a force is applied to the piston 12_i in the direction of the bottom dead center, and the direction of the current is changed to the permanent magnet position of the piston on the piston side of the electromagnet 102. If the direction of the magnet 101 is opposite to the polarity of the magnetic pole on the top dead center side, the electromagnet 102 and the permanent magnet 101 are attracted, and a force is applied to the piston 12_i in the direction of the top dead center.

  More specifically, in the electromagnet driving unit 520, in advance, for each piston 12_1-12_4, the distance between the permanent magnet 101 and the electromagnet 102 of the piston 12_i is at the reference distance and no induced electromotive force is generated in the electromagnet 102. The correspondence between the magnitude and direction of the current flowing through the electromagnet 102 and the magnitude of the force applied to the piston 12_i is registered. Then, in the electromagnet driving unit 520, for each piston 12_1-12_4, the magnitude and direction of the current corresponding to the force calculated for the piston 12_i by the multiplication unit 519 are determined by the registered magnitude and direction of the current and the force applied to the piston 12_i. Calculate according to the size of Then, the calculated current magnitude is corrected to a magnitude obtained by multiplying the calculated current magnitude by the gain Gd and the gain Gv obtained for the piston 12_i, and the current flowing to the electromagnet 102 corresponding to the piston 12_i is corrected. By using the current having the magnitude and the calculated direction, the multiplication unit 519 controls the piston 12_i so that the force calculated for the piston 12_i is applied to the piston 12_i.

  Note that the above differential pressure compensation control unit 510 actually corresponds to the differential pressure ΔP, the phase φ of the piston 12_i, the movement vector of the piston 12_i, and the piston 12_i instead of the gain table 511 and the F table 515. A current table may be provided that defines the relationship between the magnitude and direction of the current flowing through the electromagnet 102, and the magnitude and direction of the current flowing through the electromagnet 102 corresponding to the piston 12_i may be controlled according to the current table. However, the current table defines a relationship in which the differential pressure compensation control unit 510 applies a force to the piston 12_i in the same manner as the differential pressure compensation control unit 510 illustrated in FIG.

The embodiment of the invention has been described.
According to the present embodiment, the pressure loss due to the positive displacement type flow detector can be compensated without using a relatively expensive and bulky electric motor. Further, since it is not necessary to extend the crankshaft 13 of the fluid transfer device 100 to the outside of the fluid transfer device 100, the fluid does not leak from the fluid transfer device 100 due to the extending structure. Further, according to the present embodiment, the magnet coupling for transmitting the rotational torque of the electric motor to the crankshaft 13 is not used, so that the detection accuracy of the positive displacement type flow sensor due to the rotational resonance does not decrease. .

  In the above embodiment, by controlling the magnetic force generated by the electromagnet 102, when the piston 12_1-12_4 is moving toward the top dead center, a force is applied to the piston 12_1-12_4 in the direction of the top dead center, and the piston 12_1-12_4 is applied. When 12_4 is heading toward the bottom dead center, a force is applied to the piston 12_1-12_4 in a direction toward the bottom dead center. This is because when the piston 12_1-12_4 is headed toward the top dead center, By controlling the magnetic force generated by the electromagnet 102 so as to apply a force to the piston 12_1-12_4 toward the top dead center and not to apply the force when the piston 12_1-12_4 is toward the bottom dead center, When 12_1-12_4 is approaching the bottom dead center, a force is applied to the piston 12_1-12_4 in the direction of the bottom dead center, and the piston 12_1-12_4 is moved to the top dead center. It may be performed to control the magnetic force generated by the electromagnet 102 so as not to apply force when the heading.

Further, in the above embodiment, the set of the permanent magnet 101 and the electromagnet 102 is provided for all the pistons 12_1-12_4. However, the permanent magnets 101 and the electromagnets 102 are provided only for some of the four pistons 12_1-12_4. A set of the magnet 101 and the electromagnet 102 may be provided.
The technique of compensating for pressure loss using the permanent magnet 101 and the electromagnet 102 fixed to the piston 12_1-12_4 described in the embodiment is based on any positive displacement flow rate using a piston to transfer fluid from the inlet to the outlet. The same applies to detectors.

  DESCRIPTION OF SYMBOLS 10 ... Fluid transfer apparatus, 11_1-11_4 ... Cylinder, 12_1-12_4 ... Piston, 13 ... Crankshaft, 14_1-14_4 ... Connecting rod, 15_1-15_4 ... Flow path, P1-P4 ... Port, E1-E4 ... Port, 21 ... External shaft, 22 ... Rotation sensor, 23 ... Electric motor, 24 ... Differential pressure detection unit, 25 ... Flow path forming unit, 26 ... Control device, 27 ... Differential pressure sensor, 100 ... Fluid transfer device, 101 ... Permanent magnet, 102: electromagnet, 103: electromagnet unit, 111: bearing, 112: rotation detecting magnet, 200: rotation detecting unit, 201: magnetic field detecting element, 202: electronic circuit, 300: differential pressure detecting unit, 301: differential pressure sensor, 400: flow path forming unit, 500: control device, 501: flow rate measurement unit, 510: differential pressure compensation control unit, 511 Gain table, 512: Gain calculator, 513: Piston phase calculator, 514: F calculator, 515: F table, 516: Movement vector calculator, 517: Distance correction gain calculator, 518: Electromotive force correction gain calculator 519: Multiplying unit, 520: Electromagnet driving unit.

Claims (8)

With a positive displacement type flow detector equipped with one or more pistons that reciprocate by the force of the fluid flowing from the inlet and transfer the fluid flowing from the inlet to the outlet with the reciprocating movement and flow out. So,
A magnet fixed to the end of at least one said piston;
An electromagnet arranged at a position facing the magnet,
By controlling the driving of the electromagnet, a force directed to the moving direction of the magnet-equipped piston due to the magnetic force between the electromagnet and the magnet is applied to the magnet-equipped piston, which is a piston having the magnet fixed to the end portion, A positive displacement type flow detector comprising: a pressure loss compensation control means for applying a pressure difference between a fluid flowing in from an inlet and a fluid flowing out of an outlet so as to eliminate the pressure difference. The positive displacement flow detector according to claim 1,
Having a pressure difference detection means for detecting a pressure difference between the fluid flowing from the inlet and the fluid flowing out of the outlet,
The pressure loss compensation control means is configured to cause the pressure difference detected by the pressure difference detection means to approach zero as a force in the moving direction of the magnet-equipped piston, and a force corresponding to the pressure difference detected by the pressure difference detection means. And controlling the driving of the electromagnet so as to be applied to the magnet-equipped piston. It is a positive displacement type flow detector of Claim 1 or 2, Comprising:
The pressure loss compensation control means, when the piston with the magnet is moving toward the top dead center and when the piston with the magnet is moving toward the bottom dead center, the current flowing through the electromagnet By reversing the orientation, the piston with magnet both when the piston with magnet is moving toward top dead center and when the piston with magnet is moving toward bottom dead center, A positive displacement type flow detector which applies a force in a moving direction of the piston with a magnet by a magnetic force between the electromagnet and the magnet. It is a positive displacement type flow detector of Claim 3, Comprising:
A crankshaft,
A connecting rod that connects the crankshaft and the magnet-equipped piston,
Having a rotation angle detecting means for detecting a rotation angle of the crankshaft,
The pressure loss compensation control means identifies the phase of the magnet-equipped piston from the rotation angle of the crankshaft detected by the rotation angle detection means, according to the identified phase of the magnet-equipped piston, the direction of the current flowing through the electromagnet, Both when the piston with the magnet is moving toward the top dead center and when the piston with the magnet is moving toward the bottom dead center, the piston with the magnet is provided between the electromagnet and the magnet. A positive displacement type flow detector characterized in that switching is performed so that a force directed to a moving direction of the magnet-equipped piston by a magnetic force is applied. It is a positive displacement type flow detector of Claim 4, Comprising:
The pressure loss compensation control means may include at least one of a period during which the piston with magnet is moving toward top dead center and a period during which the piston with magnet is moving toward bottom dead center. During the period, the current flowing through the electromagnet in accordance with the identified phase of the magnet-equipped piston so that the magnitude of the force applied to the magnet-equipped piston in the direction of movement of the magnet-equipped piston changes. A positive displacement type flow detector characterized by changing the size of the flow rate. The positive displacement flow detector according to claim 1, 2, 3, 4, or 5,
Having a distance calculating means for calculating the distance between the electromagnet and the magnet with the reciprocating motion of the piston with the magnet,
The pressure loss compensation control means is configured to control a current flowing through the electromagnet in accordance with the distance calculated by the distance calculation means so that a force applied to the magnet-equipped piston in a movement direction of the magnet-equipped piston becomes a predetermined magnitude. A positive displacement type flow detector characterized by correcting the size of the flow rate. The positive displacement flow detector according to claim 1, 2, 3, 4, 5, or 6,
The pressure loss compensation control means is configured to reduce an induced electromotive force generated in the electromagnet with the reciprocating motion of the magnet-equipped piston so that a force applied to the magnet-equipped piston in the movement direction of the magnet-equipped piston becomes a predetermined magnitude. A positive displacement type flow detector, wherein the magnitude of a current flowing through the electromagnet is corrected accordingly. The positive displacement flow detector according to claim 1, 2, 3, 4, 5, 6, or 7,
The piston with the magnet reciprocates in the internal space, the cylinder having a top dead center side closed by a partition wall,
The magnet is fixed to the top dead center end of the magnet-equipped piston,
The positive electromagnet is fixed at a position facing the magnet outside the partition wall.