Electromagnetic pump anomaly detection device

Abstract

The present invention provides 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 abnormality detection device 200 for the electromagnetic drive pump 100 comprises an electromagnetic coil 120 arranged inside the housing 110, a guide 142 arranged inside the electromagnetic coil and electrically connected to the housing, a plunger 140 electrically connected to the guide and movable within the housing guided by the guide, a nozzle 190 that abuts against the discharge port side of the plunger, a spring 144 that biases the plunger toward the nozzle, and a detection circuit 202 that measures the electrical resistance between the housing and the nozzle. The detection circuit determines that the plunger is in a normal state and is not locked when a first resistance value R1 obtained after a predetermined time T1 has elapsed from the rise of the drive voltage applied to the electromagnetic coil is higher than a predetermined threshold R0, and a second resistance value R2 obtained after a predetermined time T2 has elapsed from the fall of the drive voltage is lower than the threshold.

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 disposed on the flow path for detecting the flow rate of the fluid and a pressure sensor for detecting the pressure inside the flow path are 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 said 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 surely detected by such a configuration.

Prior Art Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2017-147182 [Overview of the Initiative] [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 housing; an electromagnetic coil disposed inside the housing; a guide disposed inside the electromagnetic coil and electrically connected to the housing; a plunger electrically connected to the guide and movable within the housing guided by the guide; a suction port for drawing fluid into the plunger; a discharge port for discharging fluid from the plunger; a nozzle that abuts against the discharge port side of the plunger; a return spring that biases the plunger toward the nozzle; and a detection circuit for measuring the electrical resistance between the housing and the nozzle, wherein the detection circuit determines that the plunger is in a normal state and is not locked when a first resistance value obtained after a predetermined time has elapsed from the rise of the drive voltage applied to the electromagnetic coil becomes higher than a predetermined threshold, and a second resistance value obtained after a predetermined time has elapsed from the fall of the drive voltage becomes lower than the threshold. [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 figure illustrates an abnormality detection device for an electromagnetically driven pump in an embodiment of the present invention. [Figure 2] Figure 1 is a diagram illustrating the operation of the plunger of the electromagnetically driven pump. [Figure 3] Figure 1 illustrates the normal operating waveform of the electromagnetically driven pump. [Figure 4] Figure 1 illustrates an example of an abnormal drive waveform in an electromagnetically driven pump. [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 examples 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 and configuration are denoted by the same reference numerals to avoid redundant explanations, and elements not directly related to the present invention are omitted from the illustrations.

[0012] Figure 1 is a diagram illustrating an abnormality detection device 200 for an electromagnetically driven pump 100 in an embodiment of the present invention. 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 housing 110, guide 142, and plunger 140 are made of a conductive material.

[0014] The fixed core 130 is molded integrally with the housing 110 and is located inside the electromagnetic coil 120. The guide 142 is electrically connected to the housing 110. The plunger 140 is electrically connected to the guide 142 and is further guided by the guide 142, allowing it to move within the housing 110.

[0015] As shown in Figure 1, 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.

[0016] The electromagnetic drive pump 100 also includes a base 190 formed of a conductive material and a return spring (spring 144). The base 190 is attached at a position that abuts against the discharge valve 160 side of the plunger 140. As the base 190, for example, a metal such as electromagnetic stainless steel can be preferably used. Further, as shown in FIGS. 1 and 2, a gap 192 is formed between the base 190 and the guide 142. The spring 144 biases the plunger 140 toward the base 190.

[0017] FIG. 2 is a diagram for explaining the operation of the plunger 140 of the electromagnetic drive pump 100 in FIG. 1. In the electromagnetic drive pump 100, by alternately operating the ON / OFF of the current to the electromagnetic coil 120, the plunger 140 is reciprocally driven within the housing 110.

[0018] When a drive voltage is applied to the electromagnetic coil 120 (when the voltage is ON), the plunger 140 is driven in the direction of arrow A so as to move away from the base 190 against the biasing force of the spring 144 as shown in FIG. 2(a). When the plunger 140 moves away from the base 190, the guide 142 and the base 190 become non-conductive through the gap 192.

[0019] When the plunger 140 is driven in the direction of arrow A, the fluid (for example, water) in the pump chamber 112 shown in FIG. 1 is discharged from the discharge valve 160 into the gap 192 and accumulates. The gap 192 communicates with the discharge port 172 shown in FIG. 1 of the discharge port body 170.

[0020] The discharge port body 170 is formed of a non-magnetic material such as resin that does not conduct electricity. Such a discharge port body 170 prevents the formation of a magnetic path between the base 190 and the guide 142.

[0021] On the one hand, when no driving voltage is applied to the electromagnetic coil 120 (when the voltage is OFF), as shown in Fig. 2(b), the plunger 140 is returned by the biasing force of the spring 144 and driven in the direction of arrow B to contact the base 190. When the plunger 140 contacts the base 190, it fills the gap 192 to make the guide 142 and the base 190 in a conductive state. Also, when the plunger 140 is driven in the direction of arrow B, the discharge valve 160 is closed, and the fluid is sucked into the pump chamber 112 from the suction valve 150 shown in Fig. 1. At the same time, the fluid accumulated in the gap 192 is pushed out of the electromagnetic drive pump 100 through the discharge port 172.

[0022] 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 detection circuit 202. The detection circuit 202 is electrically connected to the housing-side electrode 204 attached to the housing 110 and the base-side electrode 206 attached to the base 190, and measures the electrical resistance between the housing 110 and the base 190.

[0023] In the electromagnetic drive pump 100, as shown in Fig. 2(a), when the voltage is ON, the plunger 140 and the base 190 are in a non-conductive state through the gap 192. Since the plunger 140 is conductive to the housing 110 through the guide 142, in the non-conductive state between the plunger 140 and the base 190, the electrical resistance between the housing 110 and the base 190 measured by the detection circuit 202 becomes extremely high and is detected as a resistance value of several megaohms to infinity (over limit).

[0024] Also, as shown in Fig. 2(b), when the voltage is OFF and the guide 142 and the base 190 are in a conductive state through the plunger 140, the electrical resistance between the housing 110 and the base 190 becomes extremely low and is about the circuit resistance value.

[0025] In other words, when the plunger 140 is moving back and forth normally within the housing 110 in response to the voltage being turned ON / OFF, the electrical resistance between the housing 110 and the base 190 will repeatedly become high and low.

[0026] In conventional methods, when using a vibration detection device to determine abnormalities in an electromagnetically driven pump, if there are external vibrations in the mounting environment of the electromagnetically driven pump, for example, the vibration detection device may detect these external vibrations and falsely detect an abnormality. Therefore, the inventor investigated whether it was possible to accurately detect abnormalities in an electromagnetically driven pump using factors other than vibration, and focused on the electrical resistance between the housing 110 and the nozzle 190 of the electromagnetically driven pump 100.

[0027] Figure 3 illustrates the normal operating waveform of the electromagnetically driven pump 100 shown in Figure 1. The input waveform of the voltage (drive voltage) of the electromagnetically driven pump 100 is a square wave. In the normal operating waveform of Figure 3, the first resistance value R1 at measurement time tb, after a predetermined time T1 has elapsed from the rise of the drive voltage when the voltage is turned ON (rise time ta), is higher than the threshold R0.

[0028] Furthermore, the second resistance value R2 at measurement time td, which is measured after a predetermined time T2 has elapsed from the falling edge of the drive voltage (falling edge tc) when the voltage is OFF, is lower than the threshold R0. In addition, the first resistance value R1 at measurement time tf, which is measured after a predetermined time T1 has elapsed from the rising edge of the drive voltage (rising edge te) when the voltage is ON, is higher than the threshold R0.

[0029] As shown in Figure 3, the normal drive waveform indicates that the electrical resistance between the housing 110 and the base 190 repeatedly rises and falls above the threshold R0 in response to the voltage ON / OFF state.

[0030] The detection circuit 202 then determines that the plunger 140 is moving back and forth normally within the housing 110 and is in a normal state, not locked, if, when the voltage is ON, the first resistance value R1 after a predetermined time T1 has elapsed from the rise of the drive voltage is higher than a predetermined threshold R0 (drive determination resistance value), and when the voltage is OFF, the second resistance value R2 after a predetermined time T2 has elapsed from the fall of the drive voltage is lower than the threshold R0 (see Figure 3).

[0031] The predetermined time intervals T1 and T2 from the rise and fall of the drive voltage are set appropriately, taking into account the time it takes for the plunger 140 to move.

[0032] On the other hand, the detection circuit 202 determines that the plunger 140 is locked and in an abnormal state if the electrical resistance between the housing 110 and the base 190 remains higher or lower than the threshold R0, regardless of whether the voltage is ON or OFF (see Figure 4).

[0033] Figure 4 illustrates an example of an abnormal drive waveform of the electromagnetically driven pump 100 shown in Figure 1. In the abnormal drive waveform of Figure 4(a), the first resistance value R1 at measurement times tb and tf, measured after a predetermined time T1 has elapsed from the rising edge of the drive voltage when the voltage is turned ON (rising edge ta, te), is higher than the threshold R0. However, the second resistance value R2 at measurement time td, measured after a predetermined time T2 has elapsed from the falling edge of the drive voltage when the voltage is turned OFF (falling edge tc), should be lower than the threshold R0, but is higher.

[0034] In other words, the abnormal drive waveform in Figure 4(a) indicates that the electrical resistance between the housing 110 and the base 190 remains higher than the threshold R0 regardless of whether the voltage is ON or OFF, and that the guide 142 and the base 190 remain in a non-conductive state.

[0035] As a result, the detection circuit 202 can determine that if the electrical resistance between the housing 110 and the base 190 remains higher than the threshold R0, the plunger 140 is locked in a state where it is not in contact with the base 190 (the plunger 140 is locked in a position other than the upper end).

[0036] In the abnormal drive waveform shown in Figure 4(b), the second resistance value R2 at measurement time td, which is measured after a predetermined time T2 has elapsed from the falling edge of the drive voltage when the voltage is OFF (falling edge tc), is lower than the threshold R0. However, the first resistance values ​​R1 at measurement times tb and tf, which are measured after a predetermined time T1 has elapsed from the rising edge of the drive voltage when the voltage is ON (rising edge ta, te), are lower than the threshold R0.

[0037] In other words, the abnormal drive waveform in Figure 4(b) indicates that the electrical resistance between the housing 110 and the base 190 remains lower than the threshold R0 regardless of whether the voltage is ON or OFF, and that the guide 142 and the base 190 remain in a conductive state.

[0038] As a result, the detection circuit 202 can determine that if the electrical resistance between the housing 110 and the base 190 remains lower than the threshold R0, the plunger 140 is locked in contact with the base 190 (the plunger 140 is locked at its upper end), which is an abnormal condition.

[0039] As described above, by using the electrical resistance between the housing 110 and the nozzle 190 to determine abnormalities in the electromagnetic drive pump 100, the influence of external disturbances when determining abnormalities by referring to vibration can be eliminated, and the presence or absence of abnormalities in the electromagnetic drive pump 100 can be determined more accurately. Furthermore, while conventionally used vibration detection devices are generally attached to the pump body, the abnormality determination device 200 of this embodiment consists of a detection circuit 202 electrically connected to the electromagnetic drive pump 100 via the housing-side electrode 204 and the nozzle-side electrode 206. Therefore, the abnormality determination device 200 is not subject to restrictions on the mounting location and can be applied regardless of the specifications of the pump body, thus achieving high versatility. Moreover, by applying the abnormality determination device 200, it is possible to reduce the size of the pump body and simplify the pump assembly.

[0040] 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 will be obvious 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]

[0041] This invention can be used as 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]

[0042] 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, 190...Fastener, 192...Gap, 200...Anomaly detection device, 202...Detection circuit, 204...Housing side electrode, 206...Fastener side electrode, R0...Threshold, R1...First resistance value, R2...Second resistance value, T1, T2...Determined time

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, Housing and An electromagnetic coil arranged within the housing, A guide is disposed inside the electromagnetic coil and is electrically connected to the housing, A plunger that is electrically connected to the guide and is guided by the guide and can move within the housing, The plunger has a suction port for drawing in fluid, The outlet for discharging the fluid inside the plunger, A nozzle that abuts against the discharge port side of the plunger, A return spring that biases the plunger toward the mouthpiece, The system includes a detection circuit for measuring the electrical resistance between the housing and the base, The aforementioned detection circuit is An electromagnetic pump abnormality detection device characterized in that, when a first resistance value elapsed a predetermined time from the rise of the drive voltage applied to the electromagnetic coil becomes higher than a predetermined threshold, and a second resistance value elapsed a predetermined time from the fall of the drive voltage becomes lower than the threshold, it is determined that the plunger is in a normal state and is not locked.

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