Abnormality detection device for electromagnetically driven pump

Abstract

To provide an abnormality determination device of an electromagnetic drive pump which can exactly determine the presence or absence of an abnormality of the pump without being affected by a disturbance.SOLUTION: In a constitution of an abnormality determination device of an electromagnetic drive pump according to the present invention, the abnormality determination device 200 of the electromagnetic drive pump 100 for pressure-sending fluid by reciprocating a plunger 140 by an electromagnetic coil 120 comprises: an ammeter 210 arranged on a drive circuit 202 for supplying power to the electromagnetic coil 120; and a determination part 220 for determining an abnormality from a current value which is acquired by the ammeter 210. The determination part 220 acquires a minimum value I1 of the current value within a prescribed time T after a rise of a drive voltage, and when it is determined that the minimum value I1 goes down below a threshold I0, the determination part determines that the plunger 140 is locked.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an abnormality determination device for an electromagnetically driven pump that pumps fluid by reciprocating a plunger using an electromagnetic coil. [Background technology]

[0002] Electromagnetically driven pumps, which use an electromagnetic coil as a power source, have been known as pumps for transporting fluids. In an electromagnetically driven pump, a plunger reciprocates inside a housing by switching the voltage applied to the electromagnetic coil on and off. The electromagnetically driven pump pumps (transports) the fluid by drawing it in through an inlet and discharging it through an outlet. Methods commonly used to detect abnormalities in the pump's discharge flow rate include a flow sensor that is placed in the flow path to detect the fluid flow rate, and a pressure sensor that detects the pressure within the flow path.

[0003] However, when the target flow rate is very small, the detection accuracy of the flow rate and pressure decreases. Therefore, a vibration detection device is sometimes used instead of a flow rate sensor or pressure sensor (for example, Patent Document 1). The fuel cell system in Patent Document 1 includes "a plunger-type reforming water pump that is housed in a cylinder so as to be able to move back and forth, moves when a coil is energized, and has a plunger that collides with a collision target, and supplies reforming water to an evaporation section, a vibration detection device that detects vibrations of the reforming water pump that occur when the plunger moves back and forth, and a control device that controls at least the reforming water pump."

[0004] Furthermore, the control device of Patent Document 1 includes "an abnormality determination unit that determines that an abnormality in the reforming water supply has occurred, in which reforming water is not supplied to the reforming water pump, if the amplitude of vibration detected by the vibration detection device is equal to or greater than a first determination value within a first time period during which the plunger is moving, from the time when current begins to be applied to the coil until the time when the plunger collides with the collision target." Patent Document 1 claims that this configuration makes it possible to reliably detect the occurrence of an abnormality in the reforming water supply, in which reforming water is not supplied to the pump that supplies the reforming water. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2017-147182 Summary of the Invention [Problem to be solved by the invention]

[0006] When a vibration detection device is used to determine whether a pump is abnormal, as in Patent Document 1, if there is a disturbance vibration in the installation environment of the pump, the vibration detection device may detect the disturbance vibration and determine that a pump abnormality has occurred (for example, a pump that should be stopped is operating). For this reason, although the method of using a vibration detection device as in Patent Document 1 is useful as one method for determining whether a pump is abnormal, there is room for further improvement in order to more accurately determine whether a pump is abnormal.

[0007] In view of the above problems, an object of the present invention is to provide an abnormality determination device for an electromagnetically driven pump that can accurately determine whether or not there is an abnormality in the pump without being affected by external disturbances. [Means for solving the problem]

[0008] In order to solve the above problems, a typical configuration of an abnormality determination device for an electromagnetically driven pump according to the present invention is an abnormality determination device for an electromagnetically driven pump that pumps fluid by reciprocating a plunger with an electromagnetic coil, the device comprising: an ammeter arranged on a drive circuit that supplies power to the electromagnetic coil; and a determination unit that determines an abnormality based on the current value acquired by the ammeter, the determination unit acquiring the minimum current value within a predetermined time from the fall of the drive voltage, and determining that the plunger is locked if the minimum value falls below a threshold. The abnormality determination device for an electromagnetically driven pump may also comprise a flywheel diode arranged on the drive circuit. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide an abnormality determination device for an electromagnetically driven pump that can accurately determine whether or not there is an abnormality in the pump without being affected by external disturbances. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating an abnormality determination device for an electromagnetically driven pump according to an embodiment of the present invention; [Figure 2] 5A and 5B are diagrams illustrating the operation of a plunger of an electromagnetically driven pump. [Figure 3] 4A and 4B are diagrams illustrating waveforms of current and voltage values ​​of an electromagnetically driven pump in normal and abnormal states; DETAILED DESCRIPTION OF THE INVENTION

[0011] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Dimensions, materials, and other specific values ​​shown in the embodiments are merely examples for facilitating understanding of the invention and, unless otherwise specified, do not limit the present invention. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present invention are not shown or described.

[0012] 1 is a diagram illustrating an abnormality determination device 200 for an electromagnetically driven pump 100 according to this embodiment. The electromagnetically driven pump 100 shown in FIG. 1 is a device that pumps a fluid (not shown) by causing a plunger 140 to reciprocate using an electromagnetic coil 120.

[0013] In the electromagnetically driven pump 100, an electromagnetic coil 120 is disposed inside a housing 110. Disposed inside the electromagnetic coil 120 are a fixed core 130, a cylindrical guide 142, and a plunger 140 guided by the guide 142. The fixed core 130 is molded integrally with the housing 110 and disposed inside the electromagnetic coil 120. The plunger 140 is guided by the guide 142 and is movable within the housing 110.

[0014] 2 is a diagram illustrating the operation of plunger 140 of electromagnetically driven pump 100. As shown in FIGS. 1 and 2, suction valve 150 is disposed inside fixed core 130, and discharge valve 160 is disposed inside plunger 140. Suction valve 150 draws fluid into plunger 140, and discharge valve 160 discharges the fluid inside plunger 140.

[0015] By alternately turning on and off the current to the electromagnetic coil 120, the plunger 140 reciprocates within the housing 110. As a result, when the plunger 140 is driven (moves in the direction of arrow A) as shown in FIG. 2(a), the fluid (e.g., water) in the pump chamber 112 is discharged from the discharge valve 160.

[0016] 2(b), when the plunger 140 is returned (moved in the direction of arrow B) by the spring 144, fluid is sucked into the pump chamber 112 through the suction valve 150. The discharge valve 160 communicates with a discharge port 172 of the discharge port main body 170, and seals one end of the cylindrical guide 142 (the end on the discharge valve 160 side). As a result, the fluid discharged from the discharge valve 160 is transferred to the outside of the electromagnetically driven pump 100 through the discharge port 172.

[0017] 1, an abnormality determination device 200 is connected to the electromagnetically driven pump 100. The abnormality determination device 200 includes an ammeter 210 and a determination unit 220. A power supply 204, a switch 206, a flywheel diode 208 (also referred to as a freewheel diode), and an ammeter 210 are arranged on a drive circuit 202 that supplies power to the electromagnetic coil 120 of the electromagnetically driven pump 100.

[0018] When switch 206 on drive circuit 202 is turned on, power is supplied from power supply 204 to electromagnetic coil 120. On the other hand, when switch 206 on drive circuit 202 is turned off, the supply of power from power supply 204 to electromagnetic coil 120 is stopped. At this time, a flywheel diode 208 is provided on drive circuit 202, making it possible to prevent damage to switch 206 due to flyback voltage (also called surge voltage).

[0019] The ammeter 210 acquires the current in the drive circuit 202. The ammeter 210 is connected to a determination unit 220 that determines an abnormality in the electromagnetically driven pump 100 by referring to the current value acquired by the ammeter 210. In detail, the determination unit 220 acquires the minimum value of the current value within a predetermined time from the falling edge of the drive voltage (pulse wave), and determines that the plunger 140 is locked when the minimum value falls below a threshold value. Specifically, the determination unit 220 can be implemented by a program that runs on a computer or an embedded CPU.

[0020] Here, when a vibration detection device is used to determine an abnormality in an electromagnetically driven pump as in the past, if there is a disturbance vibration in the installation environment of the electromagnetically driven pump, the vibration detection device may detect the disturbance vibration and erroneously detect an abnormality. For this reason, the inventors investigated whether it would be possible to accurately detect an abnormality in an electromagnetically driven pump using factors other than vibration, and focused on the current value at a predetermined time T after the electromagnetically driven pump 100 has stopped.

[0021] 3A and 3B are diagrams illustrating waveforms of current and voltage values ​​of the electromagnetically driven pump 100 in normal and abnormal conditions. Fig. 3A is a diagram illustrating waveforms of current and voltage values ​​of the electromagnetically driven pump 100 in normal conditions. Fig. 3B and Fig. 3C are diagrams illustrating waveforms of current and voltage values ​​of the electromagnetically driven pump 100 in abnormal conditions.

[0022] 3(a)-(c), when the electromagnetically driven pump 100 is driven (at driving time t1), the voltage value rises (increases) from 0 V to 24 V, and when the electromagnetically driven pump 100 is stopped (at stopping time t2), the voltage value falls (drops) from 24 V to 0 V. In contrast, as shown in Figures 3(a)-(c), when the electromagnetically driven pump 100 is driven (at driving time t1), the current value of the electromagnetically driven pump 100 rises in a curve and then becomes a substantially constant value, and when the electromagnetically driven pump 100 is stopped (at stopping time t2), the current value drops sharply and then gradually drops again.

[0023] In the electromagnetically driven pump 100 in which no abnormality has occurred, the minimum value I1 of the current value in the predetermined time T is equal to or greater than the threshold value I0, as shown in FIG. 3(a). In contrast, an example of an abnormality occurring in the electromagnetically driven pump 100 is when the plunger 140 is locked at the upper end, as shown in FIG. 2(b). In such a case, the minimum value I1 of the current value in the predetermined time T is less than the threshold value I0, as shown in FIG. 3(b). Another example of an abnormality occurring in the electromagnetically driven pump 100 is when the plunger 140 is locked at the lower end, as shown in FIG. 2(a). In such a case, the minimum value I1 of the current value in the predetermined time T is less than the threshold value I0, as shown in FIG. 3(c).

[0024] As described above, the abnormality determination device 200 of this embodiment determines whether an abnormality exists in the electromagnetically driven pump 100 by referring to the minimum current value I1 during the predetermined time T from the time t2 when the pump is stopped. Specifically, the abnormality determination device 200 determines whether the minimum current value I1 during the predetermined time T is below a preset threshold current value I0. If the minimum current value I1 during the predetermined time T is equal to or greater than the threshold current value I0, the abnormality determination device 200 determines that the plunger 140 is not locked, i.e., the electromagnetically driven pump 100 is normal. On the other hand, if the minimum current value I1 during the predetermined time T is less than the threshold current value I0, the abnormality determination device 200 determines that the plunger 140 is locked, i.e., that an abnormality exists in the electromagnetically driven pump 100.

[0025] By using a current value to determine an abnormality in the electromagnetically driven pump 100 as configured above, it is possible to eliminate the influence of disturbances when determining an abnormality by referring to vibrations, and more accurately determine whether or not there is an abnormality in the electromagnetically driven pump 100. Furthermore, while conventionally used vibration detection devices are generally configured to be attached to the pump body, the abnormality determination device 200 of this embodiment is disposed on the drive circuit 202 rather than on the electromagnetically driven pump 100. Therefore, there are no restrictions on the attachment location, and the device can be applied regardless of the specifications of the pump body, making it highly versatile.

[0026] 3(a), when the electromagnetically driven pump 100 is not experiencing any abnormality, the current value of the electromagnetic pump 100 drops sharply after stopping the electromagnetically driven pump 100, then starts to rise once (temporary rise), and then gradually drops again. This temporary rise in current value observed during the process of the current value dropping is a characteristic that appears only when the electromagnetically driven pump 100 is not experiencing any abnormality (when normal) in the drive circuit 202 provided with the flywheel diode 208, and does not appear when an abnormality has occurred in the electromagnetically driven pump 100 and the plunger 140 is locked. Therefore, by providing the flywheel diode 208 in the drive circuit 202 as in this embodiment, it is possible to more accurately and reliably determine whether or not there is an abnormality in the electromagnetically driven pump 100.

[0027] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to these examples. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the claims, and it is understood that these modifications and alterations also fall within the technical scope of the present invention. [Industrial Applicability]

[0028] The present invention can be used in an abnormality determination device for an electromagnetically driven pump that pumps fluid by reciprocating a plunger with an electromagnetic coil. [Explanation of symbols]

[0029] 100...electromagnetically driven pump, 110...housing, 112...pump chamber, 120...electromagnetic coil, 130...stationary core, 140...plunger, 142...guide, 144...spring, 150...suction valve, 160...discharge valve, 170...discharge port body, 172...discharge port, 200...abnormality determination device, 202...drive circuit, 204...power supply, 206...switch, 208...flywheel diode, 210...ammeter, 220...determination unit

Claims

[Claim 1] An abnormality determination device for an electromagnetically driven pump that pumps fluid by reciprocating a plunger using an electromagnetic coil, an ammeter disposed on a drive circuit that supplies power to the electromagnetic coil; a determination unit that determines an abnormality based on the current value acquired by the ammeter; a flywheel diode disposed on the drive circuit; The determination unit obtains the minimum current value within a predetermined time from the falling edge of the drive voltage, and determines that the plunger is locked if the minimum current value falls below a threshold value, and determines that the plunger is not locked if the drive voltage suddenly decreases from the falling edge and then begins to increase.

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