Electromagnetic pump anomaly detection device

Abstract

The objective is to provide an electromagnetic pump malfunction detection device that can accurately determine whether or not there is a malfunction in the pump without being affected by external vibrations. [Solution] The configuration of the electromagnetic drive pump abnormality detection device according to the present invention is an electromagnetic drive pump abnormality detection device that pumps fluid by causing a plunger to reciprocate using an electromagnetic coil, and comprises a varistor inserted in parallel with the electromagnetic coil, a voltmeter arranged on a drive circuit that supplies power to the electromagnetic coil, and a determination unit that determines an abnormality from the value acquired by the voltmeter, wherein the determination unit acquires the minimum value V1 of the voltage after a first predetermined time Ta has elapsed from the falling edge of the drive voltage and before a second predetermined time Tb has elapsed, and if the minimum value V1 falls below the threshold V0, it determines that the plunger is operating normally and that it is functioning normally, and if the minimum value V1 does not fall below the threshold V0, it determines that the plunger is locked and that it is functioning abnormally.

Description

Technical Field

[0001] The present invention relates to an abnormality determination device for an electromagnetic drive pump that reciprocates a plunger by an electromagnetic coil to pump a fluid.

Background Art

[0002] Conventionally, as a pump for transferring a fluid, an electromagnetic drive pump that uses an electromagnetic coil as power is known. The electromagnetic drive pump reciprocates a plunger inside a housing by switching ON / OFF of a voltage applied to the electromagnetic coil. At this time, the electromagnetic drive pump sucks the fluid from the suction port and discharges it from the discharge port, thereby pumping (transferring) the fluid. As a method for detecting an abnormality in the discharge flow rate of the pump, a flow rate sensor arranged on the flow path to detect the flow rate of the fluid or a pressure sensor that detects the pressure in the flow path is generally used.

[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 may be used instead of the flow rate sensor or the pressure sensor (for example, Patent Document 1). The fuel cell system of Patent Document 1 includes "a plunger-type reformed water pump that is reciprocally housed in a cylinder, moves when a coil is energized, and has a plunger that collides with a collision portion, and supplies reformed water to an evaporation portion, a vibration detection device that detects the vibration of the reformed water pump generated during the reciprocating movement of the plunger, and a control device that controls at least the reformed water pump".

[0004] Further, the control device of Patent Document 1 includes "an abnormality determination unit that determines that a reformed water supply abnormality has occurred in which reformed water is not supplied to the reformed water pump when the amplitude of the vibration detected by the vibration detection device is greater than or equal to a first determination value within a first time period during which the plunger is moving from the start time of energization of the coil to the collision time when the plunger collides with the collision portion". According to Patent Document 1, it is stated that the occurrence of a reformed water supply abnormality in which reformed water is not supplied to the pump that supplies reformed water can be reliably detected by such a configuration.

Prior Art Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2017-147182 [Overview of the project] [Problems that the invention aims to solve]

[0006] When a vibration detection device is used to determine a pump malfunction, as described in Patent Document 1, if there is external vibration in the pump's mounting environment, for example, the vibration detection device may detect this external vibration and mistakenly determine that a pump malfunction has occurred (for example, the pump is running when it should be stopped). Therefore, while the method using a vibration detection device as described in Patent Document 1 is useful as one method for determining a pump malfunction, there is room for further improvement in order to more accurately determine whether or not a pump malfunction has occurred.

[0007] In view of these problems, the present invention aims to provide an electromagnetic pump abnormality detection device that can accurately determine whether or not there is an abnormality in the pump without being affected by external vibrations. [Means for solving the problem]

[0008] To solve the above problems, a typical configuration of the electromagnetic drive pump abnormality detection device according to the present invention is an electromagnetic drive pump abnormality detection device that pumps fluid by causing a plunger to reciprocate using an electromagnetic coil, comprising a varistor inserted in parallel with the electromagnetic coil, a voltmeter placed on a drive circuit that supplies power to the electromagnetic coil, and a determination unit that determines an abnormality from the value acquired by the voltmeter, wherein the determination unit acquires the minimum value V1 of the voltage after a first predetermined time Ta has elapsed from the falling edge of the drive voltage and before a second predetermined time Tb has elapsed, and determines that the plunger is operating normally if the minimum value V1 is below the threshold V0, and determines that the plunger is locked if the minimum value V1 is not below the threshold V0. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide an electromagnetic pump abnormality detection device that can accurately determine whether or not there is an abnormality in the pump without being affected by external vibrations. [Brief explanation of the drawing]

[0010] [Figure 1] This diagram illustrates the abnormality detection device for an electromagnetically driven pump according to this embodiment. [Figure 2] This is a diagram illustrating the operation of the plunger in an electromagnetically driven pump. [Figure 3] This diagram illustrates the voltage and current waveforms of an electromagnetically driven pump under normal and abnormal conditions. [Figure 4] This diagram illustrates the voltage and current waveforms of an electromagnetically driven pump under normal and abnormal conditions. [Modes for carrying out the invention]

[0011] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. The dimensions, materials, and other specific numerical values ​​shown in these embodiments are merely illustrative to facilitate understanding of the invention and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same function or configuration are denoted by the same reference numerals to avoid redundant explanations, and elements not directly related to the present invention are not shown or described.

[0012] Figure 1 is a diagram illustrating an abnormality detection device 200 for an electromagnetically driven pump 100 according to this embodiment. The electromagnetically driven pump 100 shown in Figure 1 is a device that pumps 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 located inside the housing 110. Inside the electromagnetic coil 120 are a fixed iron core 130, a cylindrical guide 142, and a plunger 140 guided by the guide 142. The fixed iron core 130 is molded integrally with the housing 110 and is located inside the electromagnetic coil 120. The plunger 140 is movable within the housing 110, guided by the guide 142.

[0014] Figure 2 illustrates the operation of the plunger 140 of the electromagnetically driven pump 100. As shown in Figures 1 and 2, a suction valve 150 is located inside the fixed iron core 130, and a discharge valve 160 is located inside the plunger 140. The suction valve 150 draws fluid into the plunger 140, and the discharge valve 160 discharges the fluid from inside the plunger 140.

[0015] By alternating the ON / OFF operation of 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 Figure 2(a), the fluid (e.g., water) in the pump chamber 112 is discharged from the discharge valve 160.

[0016] On the other hand, as shown in Figure 2(b), when the plunger 140 returns due to the spring 144 (when it moves in the direction of arrow B), fluid is drawn into the pump chamber 112 from the suction valve 150. The discharge valve 160 communicates with the discharge port 172 of the discharge port 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] As a feature of this embodiment, as shown in FIG. 1, an abnormality determination device 200 is connected to the electromagnetic drive pump 100. The abnormality determination device 200 includes a voltmeter 210 that measures the voltage applied to the electromagnetic coil 120 and a determination unit 220. On the drive circuit 202 that supplies power to the electromagnetic coil 120 of the electromagnetic drive pump 100, a power supply 204, a switch 206, a varistor 208 inserted in parallel with the electromagnetic coil 120, and a voltmeter 210 are arranged.

[0018] When the switch 206 on the drive circuit 202 is in the ON state, power from the power supply 204 is supplied to the electromagnetic coil 120. On the other hand, when the switch 206 on the drive circuit 202 is in the OFF state, the supply of power from the power supply 204 to the electromagnetic coil 120 stops. At this time, due to the arrangement of the varistor 208 on the drive circuit 202, it is possible to prevent damage to the switch 206 caused by the flyback voltage (also referred to as the surge voltage), similar to the case where a flywheel diode (freewheeling diode) is arranged.

[0019] The voltmeter 210 acquires the voltage in the drive circuit 202. A determination unit 220 that determines the abnormality of the electromagnetic drive pump 100 by referring to the voltage acquired by the voltmeter 210 is connected to the voltmeter 210. Specifically, the determination unit 220 can be implemented by a program operating on a computer or an embedded CPU.

[0020] Specifically, the determination unit 220 acquires the minimum value V1 of the voltage after the elapse of the first predetermined time Ta from the fall of the drive voltage and before the elapse of the second predetermined time Tb. Then, when the minimum value V1 is lower than the threshold value V0, the determination unit 220 makes a normal determination that the plunger is operating normally, and when the minimum value V1 is not lower than the threshold value V0, the determination unit 220 makes an abnormality determination that the plunger is locked.

[0021] The first predetermined time Ta is a time for excluding the time during which the voltage vibrates both in normal and abnormal conditions. The first predetermined time Ta can be appropriately determined as the time until the vibration converges to a certain extent according to the time constant of the attenuation of the voltage vibration determined by the inductance of the electromagnetic coil and the varistor voltage. The start and end of the second predetermined time Tb are appropriately determined so as to include the timing when the plunger 140 returns by the spring 144.

[0022] Here, when determining the abnormality of the electromagnetic drive pump using a vibration detection device as in the prior art, for example, if there is external disturbance vibration in the installation environment of the electromagnetic drive pump, the vibration detection device may detect the external disturbance vibration and misdetect the abnormality. Therefore, the inventor considered whether the abnormality of the electromagnetic drive pump can be accurately detected by factors other than vibration, and focused on the voltage fluctuation during the period from the first predetermined time Ta to the second predetermined time Tb after the electromagnetic drive pump 100 stops.

[0023] FIG. 3 and FIG. 4 are diagrams illustrating the voltage and current waveforms of the electromagnetic drive pump 100 in normal and abnormal conditions. FIG. 3(a) is a diagram illustrating the waveform in normal condition. FIG. 3(b), FIG. 4(a) and (b) are diagrams illustrating the waveforms in abnormal conditions.

[0024] Specifically, FIG. 3(b) is the waveform when the plunger 140 abnormally stops at the upper end position. FIG. 4(a) is the waveform when the plunger 140 abnormally stops at the intermediate position. FIG. 4(b) is the waveform when the plunger 140 abnormally stops at the lower end position. Note that the abnormal stop means the state where the plunger is locked at each position.

[0025] The input waveform of the electromagnetic drive pump 100 (drive voltage) is a square wave, but the voltage fluctuates due to the influence of the electromagnetic coil 120 and other elements. As illustrated in Figures 3 and 4, when the electromagnetic drive pump 100 is driven (during drive t1), the voltage rises from 0V to 24V, and when the electromagnetic drive pump 100 is stopped (during stop t2), the voltage falls from 24V to 0V. The current of the electromagnetic drive pump 100, as illustrated in Figures 3 and 4, rises in a curve when the electromagnetic drive pump 100 is driven (during drive t1) and then becomes almost constant, and when the electromagnetic drive pump 100 is stopped (during stop t2), it drops sharply and then gradually decreases.

[0026] In the electromagnetically driven pump 100 under normal operation, as illustrated in Figure 3(a), during the first predetermined time Ta, the voltage, which dropped significantly when the electromagnetically driven pump stopped at t2, rises to near 0V, after which vibration damping (fine fluctuations) occurs. After the first predetermined time Ta has elapsed, and before the second predetermined time Tb has elapsed, a waveform that swings to the negative side is observed. This is the electromotive force when the plunger 140 returns due to the spring 144. A threshold V0 is set between the minimum value V1, which is the peak of this waveform, and 0V. After the second predetermined time Tb has elapsed, the voltage is almost 0V.

[0027] In the electromagnetically driven pump 100 during an abnormal state, as illustrated in Figures 3(b), 4(a), and 4(b), the voltage drops sharply at t2 when the electromagnetically driven pump stops, rises to around 0V during the first predetermined time Ta as in the normal state, and fine fluctuations (vibration damping) occur. Here, in the electromagnetically driven pump 100 during an abnormal state, after the first predetermined time Ta has elapsed and before the second predetermined time Tb has elapsed, no peak below the threshold V0 occurs, and the voltage is almost 0V. This is because the plunger 140 does not move and no electromotive force is generated. Furthermore, the voltage remains almost 0V even after the second predetermined time Tb has elapsed.

[0028] Therefore, the abnormality detection device 200 of this embodiment determines an abnormality in the electromagnetic drive pump 100 by referring to the minimum voltage V1 between the time of stopping t2 and the second predetermined time Tb, which is the voltage waveform shown in Figures 3 and 4. Specifically, the abnormality detection device 200 determines whether the minimum voltage V1 at the second predetermined time Tb is below a preset voltage threshold V0.

[0029] The abnormality detection device 200 determines that the plunger 140 is not locked, i.e., the electromagnetically driven pump 100 is functioning normally, if the minimum voltage V1 between Ta and Tb over a predetermined period of time falls below the threshold V0. On the other hand, the abnormality detection device 200 determines that the plunger 140 is locked, i.e., an abnormality has occurred in the electromagnetically driven pump 100, if the minimum voltage V1 between Ta and Tb over a predetermined period of time does not fall below the threshold V0.

[0030] As described above, by using voltage to determine abnormalities in the electromagnetically driven pump 100, the influence of external vibrations, which are often used when determining abnormalities by referring to vibrations, can be eliminated, allowing for a more accurate determination of whether or not there is an abnormality in the electromagnetically driven pump 100. Furthermore, while conventionally used vibration detection devices are generally mounted on the pump body, the abnormality determination device 200 in this embodiment is located on the drive circuit 202 rather than on the electromagnetically driven pump 100. Therefore, it is not subject to mounting location constraints and can be applied regardless of the specifications of the pump body, thus achieving high versatility.

[0031] In Figure 1, a flywheel diode (recirculating diode) is typically placed where the varistor 208 is located. However, if a diode is placed, the voltmeter 210 will measure the forward voltage drop of the diode (typically 0.6V). In this case, even if an electromotive force is generated in the plunger 140, the voltage can only be measured down to -0.6V, and the threshold V0 will be set to half of that, around -0.3V, which may lead to increased false detections due to the pickup of voltage fluctuations. In contrast, the varistor 208 has a high resistance value at voltages below the varistor voltage, and almost no current flows from the electromotive force of the plunger 140. Therefore, the voltage of the electromotive force can be picked up to the maximum extent (the voltage rises in accordance with the electromotive force), making it possible to realize abnormality detection by voltage as in the present invention.

[0032] Preferred embodiments of the present invention have been described above with reference to the attached drawings, but it goes without saying that the present invention is not limited to these examples. It is clear to those skilled in the art that various modifications or alterations can be conceived within the scope of the claims, and these will naturally also fall within the technical scope of the present invention. [Industrial applicability]

[0033] This invention can be used in an abnormality detection device for an electromagnetically driven pump that pumps fluid by causing a plunger to reciprocate using an electromagnetic coil. [Explanation of Symbols]

[0034] V0...Threshold, Ta...Determined time, V1...Minimum value, Tb...Determined time, 100...Electromagnetic driven pump, 110...Housing, 112...Pump chamber, 120...Electromagnetic coil, 130...Fixed iron core, 140...Plunger, 142...Guide, 144...Spring, 150...Suction valve, 160...Discharge valve, 170...Discharge port body, 172...Discharge port, 200...Anomaly detection device, 202...Drive circuit, 204...Power supply, 206...Switch, 208...Varistor, 210...Voltmeter

Claims

[Claim 1] An abnormality detection device for an electromagnetically driven pump that pumps fluid by causing a plunger to reciprocate using an electromagnetic coil, A varistor inserted in parallel with the aforementioned electromagnetic coil, A voltmeter placed on the drive circuit that supplies power to the electromagnetic coil, The system includes a determination unit that determines an abnormality from the value acquired by the voltmeter, The determination unit, After a first predetermined time has elapsed since the fall of the drive voltage, and before a second predetermined time has elapsed, the minimum value of the voltage is obtained. If the minimum value falls below the threshold, the plunger is determined to be operating normally. An abnormality detection device for an electromagnetically driven pump, characterized in that it determines that the plunger is locked if the minimum value does not fall below a threshold.

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