JP2011075497A - Position detecting method of movable element of electromagnetic actuator, and detection device therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a position detection method and device of a movable element of an electromagnetic actuator, which detects accurately a plunger position, even if two points exist, which have each equal inductance of a coil and each different air gap between the plunger and the bottom of a stator, by generating magnetic saturation. <P>SOLUTION: This method has: a first process for applying a fluctuating voltage to a coil 5; a second process for measuring a rising or falling state of a current flowing in the coil 5 generated by application of the fluctuating voltage a plurality of times during rising and falling; and a third process for determining the position of the movable element 6 by comparing respectively a plurality of measured values acquired in the second process with a measured value or a calculated value used as a reference. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for detecting the position of a mover of an electromagnetic actuator that includes a coil and a mover and is used, for example, for the operation of an on-off valve or a switching valve, and a detection apparatus therefor.

  In the conventional method of detecting the position of the mover of the electromagnetic actuator, when a solenoid having a plunger inserted in the coil is changed in accordance with the stroke amount of the plunger and a voltage having a constant frequency is applied to the coil. In addition, the fact that the amplitude of the current flowing through the coil varies depending on the inductance of the coil has been utilized. That is, the amplitude of the current flowing in the coil is measured by measuring the amplitude of the current flowing in the coil by utilizing the fact that the amplitude of the current flowing in the coil changes depending on the stroke amount of the plunger when a voltage of a constant frequency is applied to the coil. The position was detected. (For example, see Patent Document 1)

JP-A-2005-317612 (pages 7-8, FIG. 2 and FIG. 3)

  In such a method for detecting the position of the mover of the electromagnetic actuator, the coil inductance increases as the air gap between the plunger, which is the mover, and the bottom of the stator, to which the plunger is attracted by the excitation of the coil, becomes smaller. It is going to be. That is, it is assumed that there is a one-to-one relationship between the air gap between the plunger and the bottom of the stator and the inductance of the coil. However, in practice, in the range where the air gap is sufficiently large, the inductance increases as the air gap decreases. However, when the air gap becomes smaller than a certain distance, magnetic saturation occurs, and conversely, the inductance decreases. That is, the inductance takes a maximum value at the point where magnetic saturation starts to occur. Therefore, there are two points with the same inductance and different air gaps, and there is a problem that the position of the plunger cannot be accurately detected.

  The present invention has been made to solve the above-described problems, and even if there are two points where the coil inductance is equal and the air gap between the plunger and the bottom of the stator is different due to magnetic saturation. An object of the present invention is to provide a position detection method and a detection device for a mover of an electromagnetic actuator capable of accurately detecting the position of a plunger.

  According to the method for detecting the position of the mover of the electromagnetic actuator according to the present invention, the first step of applying the varying voltage to the coil and the rising or falling state of the current flowing in the coil caused by the application of the varying voltage A second step of measuring a plurality of times in between, a third step of obtaining the position of the mover by comparing the plurality of measured values obtained in the second step with the measured value or the calculated value as a reference, respectively , With.

  In addition, the position detecting device for the mover of the electromagnetic actuator according to the present invention includes a power source that applies a varying voltage to the coil, a current detector that detects a current flowing through the coil, and a current flowing through the coil that is generated by the application of the varying voltage. A mover that compares the time measurement unit that measures the time from when the rise or fall starts, the multiple measurement values obtained by the current detection unit or time measurement unit, and the reference measurement value or calculation value And a position detection unit for obtaining the position of.

  According to the method for detecting the position of the mover of the electromagnetic actuator according to the present invention, the first step of applying the fluctuating voltage to the coil, and the rising or falling state of the current flowing through the coil are set between the rising and falling states. A second step of performing the multiple times measurement, and a third step of obtaining the position of the movable element by comparing the plurality of measured values obtained in the second step with the reference measured value or calculated value, respectively. Thus, even if there are two points where magnetic saturation occurs and the coil inductance is equal and the air gap between the mover and the bottom of the stator is different, the position of the mover can be accurately detected.

  In addition, according to the position detecting device for the mover of the electromagnetic actuator according to the present invention, the power source for applying the fluctuating voltage to the coil, the current detecting unit for detecting the current flowing through the coil, and the rising or falling of the current flowing through the coil The position of the mover is obtained by comparing the time measurement unit that measures the time from the start of the measurement, the multiple measurement values obtained by the current detection unit or the time measurement unit, and the reference measurement value or calculation value. Since the magnetic saturation occurs, the position of the mover can be accurately determined even if there are two points where the coil inductance is equal and the air gap between the mover and the bottom of the stator is different. It can be detected.

It is a partial cross section figure which shows the structure of the electromagnetic actuator provided with the position detection apparatus in Embodiment 1 of this invention. It is a figure which shows the relationship between the air gap in the electromagnetic actuator in Embodiment 1 of this invention, and the inductance of a coil. It is a block diagram which shows the structure of the position detection apparatus in Embodiment 1 of this invention. It is a figure which shows the waveform of the voltage and electric current at the time of applying a rectangular wave voltage to the coil in Embodiment 1 of this invention, (a) is a figure which shows the voltage waveform applied to a coil, (b) is a coil It is a figure which shows the electric current waveform which flows. It is a figure which shows the relationship between the electric current which flows into the coil when the air gap in the electromagnetic actuator in Embodiment 1 of this invention is fixed, and the inductance of a coil. It is a figure which shows the electric current waveform which flows into a coil at the time of applying a rectangular wave voltage to the coil in Embodiment 1 of this invention. It is a figure which shows the table which shows the relationship between the measured value in the time measurement part in Embodiment 1 of this invention, and an air gap, (a) is a figure which shows a 1st table, (b) shows a 2nd table. FIG. It is a block diagram which shows the structure of the position detection apparatus in Embodiment 2 of this invention. It is a block diagram which shows the structure of the position detection apparatus in Embodiment 3 of this invention. It is a figure which shows the waveform of the voltage and electric current at the time of applying a rectangular wave voltage to the coil in Embodiment 3 of this invention, (a) is a figure which shows the voltage waveform applied to a coil, (b) is a coil The figure which shows the current waveform which flows, (c) is a figure which shows the reference current waveform obtained from a coil model. It is a figure which shows the current waveform which flows into the coil in Embodiment 3 of this invention, and the reference current waveform obtained from a coil model, (a) is a figure which shows the case where a needle | mover exists in x = Pa = 0, (b) ) Is a diagram showing a case where a mover exists at x = Pc. It is a block diagram which shows the structure of the position detection apparatus in Embodiment 4 of this invention. It is a figure which shows the waveform of the voltage and electric current at the time of applying a rectangular wave voltage to the coil in Embodiment 4 of this invention, (a) is a figure which shows the voltage waveform applied to a coil, (b) is a coil The figure which shows the current waveform which flows, (c) is a figure which shows the rising waveform of the electric current which flows into a coil, (d) is a figure which reversely shows the falling waveform of the electric current which flows through a coil. It is a figure which shows the rising waveform and falling waveform of the electric current which flow in the coil in Embodiment 4 of this invention, (a) is a figure which shows the case where a needle | mover exists in x = Pa = 0, (b) is x It is a figure which shows the case where a needle | mover exists in = Pc.

  Hereinafter, with reference to the accompanying drawings, according to the method for detecting the position of the mover of the electromagnetic actuator according to the present invention, the position detection device for the mover of the electromagnetic actuator configured to be able to detect the position of the mover of the electromagnetic actuator is suitable. Embodiments will be described.

Embodiment 1 FIG.
FIG. 1 is a partial cross-sectional view showing a configuration of an electromagnetic actuator 2 provided with a position detection device 1a according to Embodiment 1 of the present invention. First, the outline of the structure of the electromagnetic actuator 2 provided with the position detection apparatus 1a in Embodiment 1 of this invention is demonstrated.

  In FIG. 1, the electromagnetic actuator 2 includes a coil 5 and a mover 6 inserted into the coil 5, and the mover 6 is formed of a magnetic material such as iron, for example. A power source 7 is connected to the coil 5, and a DC voltage and a variable voltage such as a rectangular wave or a triangular wave can be applied to the coil 5. The position detection device 1a is connected to the power source 7 and the coil 5 so that the voltage applied from the power source 7 to the coil 5 and the current flowing through the coil 5 can be detected. Here, the power source 7 can apply both a DC voltage and a fluctuating voltage. However, the power source 7 can only apply a DC voltage, and the position detecting device 1a has a power source that can apply a fluctuating voltage. May be.

  A spring 10 is attached to the mover 6, and when no voltage is applied to the coil 5, the mover 6 is in an initial position where the air gap x between the mover 6 and the bottom of the stator 11 is widened. Exists. When a DC voltage is applied to the coil 5 by the power source 7, a current flows through the coil 5 to generate magnetic flux, and the mover 6 receives a force in a direction in which the air gap x between the mover 6 and the bottom of the stator 11 is narrowed. It stops at the air gap x where the attractive force by the magnetic flux and the elastic force of the spring 10 are balanced. By adjusting the voltage applied to the coil 5, the mover 6 can take any position from the initial position to the position where the air gap x = 0.

  Next, the relationship between the air gap x and the inductance L of the coil 5 in the electromagnetic actuator 2 will be described. FIG. 2 is a diagram showing the relationship between the air gap x and the inductance L of the coil 5 in the electromagnetic actuator 2 according to Embodiment 1 of the present invention. In FIG. 2, the horizontal axis represents the air gap x between the mover 6 and the bottom of the stator 11, and the vertical axis represents the inductance L of the coil 5.

  In FIG. 2, in the range where the air gap x is sufficiently large, the magnetic resistance decreases as the air gap x decreases, so the magnetic flux density increases and the inductance L increases monotonously. However, the magnetic flux density does not increase infinitely, and when the air gap x becomes smaller than Pb, magnetic saturation occurs. Conversely, as the air gap x becomes smaller, the inductance L also becomes smaller. That is, the inductance L takes a maximum value when x = Pb.

  When the current flowing through the coil 5 is increased, the point Pb at which magnetic saturation begins to occur, that is, the point Pb at which the inductance L takes a maximum value increases, and when the current is decreased, Pb decreases. Further, the maximum value of the inductance L also changes depending on the magnitude of the current. As described above, the relationship between the air gap x and the inductance L changes when the magnitude of the current flowing through the coil 5 is changed. However, when the magnitude of the current is made constant, the relation between the air gap x and the inductance L is uniquely determined.

  As described above, since the inductance L takes a maximum value with respect to the change of the air gap x, the inductance L becomes equal at two points, for example, x = Pa = 0 and x = Pc. For this reason, the conventional method of measuring the amplitude of the current flowing by the fluctuating voltage applied to the coil 5 cannot distinguish these two points.

  Next, the configuration of the position detection device 1a according to the first embodiment of the present invention, which can discriminate two points having the same inductance L and different air gaps x as described above, will be described. FIG. 3 is a block diagram showing the configuration of the position detection device 1a according to the first embodiment of the present invention.

  In FIG. 3, when a varying voltage is applied to the coil 5 by the power source 7, a current flowing in the coil 5 rises, and this current is detected by the current detection unit 12. A signal from the current detection unit 12 and a signal of an applied voltage from the power source 7 are input to the time measurement unit 15, and a signal from the time measurement unit 15 is input to the comparison unit 17 of the position detection unit 16a. The position detection unit 16a includes a first table 20a and a second table 21a in which the relationship between the measurement value in the time measurement unit 15 and the air gap x is related via the inductance L. In the comparison unit 17, the time measurement unit 15 is compared with the first table 20a and the second table 21a to determine the air gap x, that is, the position of the movable element 6.

  Here, the first table 20a and the second table 21a are obtained by actually measuring the relationship between the measured value in the time measuring unit 15 and the air gap x in advance.

  Next, the operation of the position detection device 1a according to Embodiment 1 of the present invention will be described. Here, as an example, a case will be described in which the position of the mover 6 is obtained when the mover 6 exists in either x = Pa = 0 or x = Pc in FIG.

  First, the mover 6 exists in either x = Pa = 0 or x = Pc, and a DC voltage is applied to the coil 5 so that a current sufficient to hold the position of the mover 6 is applied.

  Next, as a first step, a variable voltage such as a rectangular wave, a triangular wave, or a sawtooth wave is applied to the coil 5. This fluctuating voltage has a DC offset in which a current sufficient to hold the position of the mover 6 flows through the coil 5, and the amplitude thereof is such that the position of the mover 6 does not fluctuate. Here, a case where a rectangular wave voltage is applied as the variable voltage will be described.

  4 is a diagram showing voltage and current waveforms when a rectangular wave voltage is applied to the coil 5 according to Embodiment 1 of the present invention. FIG. 4A is a diagram showing a voltage waveform applied to the coil 5. FIG. (B) is a figure which shows the electric current waveform which flows into the coil 5. FIG. In (a) and (b), the horizontal axis indicates time, in (a) the vertical axis indicates voltage, and in (b), the vertical axis indicates current.

  In the first step, when the rectangular wave voltage shown in FIG. 4A is applied to the coil 5, the current flowing through the coil 5 corresponds to the time constant determined by the inductance L and the resistance, as shown in FIG. 4B. A rise occurs.

  Next, the second step will be described. The current detection unit 12 detects the current flowing through the coil 5 and outputs a signal to the time measurement unit 15 when the current value has changed by a predetermined current change amount Δil, Δih from the time of applying the rectangular wave voltage. .

  When the time measurement unit 15 receives a signal from the power supply 7 that a rectangular wave voltage has been applied, the time measurement starts. And when the signal which the electric current which flows into the coil 5 changed only (DELTA) il and (DELTA) ih is received from the electric current detection part 12, each time measurement will be stopped. That is, the time measuring unit 15 measures a time tl taken until the current changes by Δil and a time th taken by the change of Δih. Information on the time tl and the time th, which are measurement values obtained by the time measurement unit 15, is input to the comparison unit 17 of the position detection unit 16a.

  Next, the third step will be described. The comparison unit 17 compares each measured value with the first table 20a and the second table 21a to obtain the air gap x, that is, the position of the mover 6.

  Next, how to determine the position of the mover 6 in the position detection unit 16a in the third step will be described. FIG. 5 is a diagram showing the relationship between the current flowing through the coil 5 and the inductance L of the coil 5 when the air gap x in the electromagnetic actuator 2 according to Embodiment 1 of the present invention is fixed. In FIG. 5, the horizontal axis indicates the current flowing through the coil 5, and the vertical axis indicates the inductance L of the coil 5. The relationship between current and inductance L at x = Pa = 0 is indicated by a solid line, and the relationship between current and inductance L at x = Pc is indicated by a broken line.

  Since magnetic saturation occurs when x = Pa = 0, the inductance L decreases as the current increases. However, when x = Pc, magnetic saturation does not occur, and the inductance L is constant regardless of the current.

  That is, when x = Pa = 0 in which magnetic saturation occurs, the time constant at the rise of the current flowing through the coil 5 when a rectangular wave voltage is applied to the coil 5 changes with the value of the current. On the other hand, when x = Pc where magnetic saturation does not occur, the current rises with a constant time constant.

  FIG. 6 is a diagram showing a current waveform flowing in the coil 5 when a rectangular wave voltage is applied to the coil 5 in the first embodiment of the present invention. In FIG. 6, the horizontal axis indicates the time after the rectangular wave voltage is applied to the coil 5, and the vertical axis indicates the amount of change of the current flowing through the coil 5 after the rectangular wave voltage is applied. A current waveform at x = Pa = 0 is indicated by a solid line, and a current waveform at x = Pc is indicated by a broken line.

  As described above, when x = Pa = 0 where magnetic saturation occurs, the time constant at the rising edge of the current changes every time depending on the value of the current, but when x = Pc where magnetic saturation does not occur, the time constant is constant. It is. Therefore, as shown in FIG. 6, the time th1 taken until the current when x = Pc changes by Δih is equal to the time th2 taken by the current when x = Pa changes by Δih, that is, Even if the average inductance L is equal, the entire rising waveforms of both currents do not match.

  Therefore, the time tl1 taken until the current when x = Pc changes by Δil does not match the time tl2 taken by the current when x = Pa changes by Δil. On the other hand, even if tl1 = tl2, th1 and th2 do not match. Using this fact, by comparing the measured values th and tl with the first table 20a and the second table 21a, it is possible to discriminate between x = Pa = 0 and x = Pc having the same inductance L. .

  FIG. 7 is a diagram showing a table showing the relationship between the measurement value in the time measurement unit 15 and the air gap x in Embodiment 1 of the present invention, (a) is a diagram showing the first table 20a, (b) ) Is a diagram showing the second table 21a. In (a) and (b), the horizontal axis indicates the air gap x. In (a), the vertical axis indicates the time th required for the current to change by Δih, and in (b), the vertical axis indicates the time until the current changes by Δil. The time tl taken is shown.

  Here, consider a case where th = tha. The comparison unit 17 compares the measurement value tha in the time measurement unit 15 with the first table 20a shown in FIG. 7A, so that the movable element 6 exists at x = Pa = 0 or x = Pc. I understand that.

  Here, when tl = tla, the comparison unit 17 compares the measured value tla with the second table 21a shown in FIG. 7B, so that the mover 6 has x = Pa = 0 or x = Pd exists.

  Therefore, from the comparison between the measurement value tha and the first table 20a and the comparison between the measurement value tla and the second table 21a, it can be seen that the movable element 6 exists at x = Pa.

  When t1 = tlc, it is found that the movable element 6 exists at x = Pc by comparing the measured value tlc with the second table 21a shown in FIG. 7B.

  In the first embodiment of the present invention, since the above configuration is adopted, there are two points in which the magnetic gap causes the inductance L of the coil 5 to be equal and the air gap x between the mover 6 and the bottom of the stator 11 is different. Even if it exists, these two points can be discriminated, and the position of the mover 6 can be uniquely determined. In addition, since the position of the mover 6 can be detected while the mover 6 is held at a fixed position, even if the position cannot be detected due to some noise, detection can be repeated any number of times. , Detection reliability is improved. Furthermore, since it is only necessary to measure the times tl and th as measured values, the position of the mover 6 can be easily detected without requiring a complicated configuration.

  In the first embodiment of the present invention, two values are defined in advance for the amount of current change, and the time corresponding to the two values is measured by the time measuring unit 15 during the rise of the current of the coil 5. . However, the number of current changes defined in advance is not limited to two, and more values may be defined and the time corresponding to each value may be measured. Reliability is improved by obtaining more measurements. In order to obtain more measurement values, it is necessary to further provide a table corresponding to each measurement value.

  In the first embodiment of the present invention, the measurement is performed during the rise of the current of the coil 5 when the variable voltage is applied. However, the measurement may be performed during the fall of the current of the coil 5.

Embodiment 2. FIG.
FIG. 8 is a block diagram showing a configuration of a position detection device 1b according to Embodiment 2 of the present invention. 8, the same reference numerals as those in FIG. 3 denote the same or corresponding components, and the description thereof is omitted. The first embodiment of the present invention is that the current detection unit 12 measures the current flowing through the coil 5 by a signal from the time measurement unit 15 in the second step, and the position detection unit 16b is a measurement by the current detection unit 12. The configuration including the first table 20b and the second table 21b in which the relationship between the value and the air gap x is related via the inductance L is different.

  Next, the operation of the position detection device 1b having such a configuration will be described. When the rectangular wave voltage shown in FIG. 4A is applied to the coil 5 in the first step, the current flowing through the coil 5 corresponds to the time constant determined by the inductance L and resistance, as shown in FIG. 4B. A rise occurs.

  Next, the second step will be described. The time measurement unit 15 starts time measurement when receiving a signal indicating that a rectangular wave voltage has been applied from the power supply 7 and outputs a signal to the current detection unit 12 when the predetermined time tl and th have elapsed.

  The current detection unit 12 measures the current flowing through the coil 5 when receiving a signal from the time measurement unit 15. That is, the current detection unit 12 measures the current change amount Δil during the time tl and the current change amount Δih during the time th.

  Next, the third step will be described. Information on the current change amounts Δil and Δih, which are measured values obtained by the current detection unit 12, is input to the comparison unit 17 of the position detection unit 16b. In the comparison part 17, each measured value is compared with the 1st table 20b and the 2nd table 21b, and the air gap x, ie, the position of the needle | mover 6, is calculated | required.

  In the second embodiment of the present invention, because of the above-described configuration, there are two points in which the magnetic saturation causes the inductance L of the coil 5 to be equal and the air gap x between the mover 6 and the bottom of the stator 11 is different. Even if it exists, these two points can be discriminated, and the position of the mover 6 can be uniquely determined. In addition, since the position of the movable element 6 can be detected while the movable element 6 is held at a fixed position, even if the position cannot be detected due to some noise, the detection can be repeated many times. Detection reliability is improved. Furthermore, since it is only necessary to measure the current change amounts Δil and Δih as measured values, the position of the mover 6 can be easily detected without requiring a complicated configuration.

Embodiment 3 FIG.
FIG. 9 is a block diagram showing a configuration of a position detection device 1c according to Embodiment 3 of the present invention. 9, the same reference numerals as those in FIG. 3 denote the same or corresponding components, and the description thereof is omitted. This embodiment is different from the first embodiment in that the position detection unit 16c includes a coil model 25 and the second table 21a is omitted.

  Next, the operation of the position detection apparatus 1c having such a configuration will be described. Here, a case will be described in which the position of the movable element 6 is obtained when the movable element 6 exists in either x = Pa = 0 or x = Pc in FIG. FIG. 10 is a diagram showing voltage and current waveforms when a rectangular wave voltage is applied to the coil 5 according to Embodiment 3 of the present invention, and (a) is a diagram showing a voltage waveform applied to the coil 5; (B) is a figure which shows the current waveform which flows into the coil 5, (c) is a figure which shows the reference current waveform obtained from the coil model 25. FIG. In (a), (b), and (c), the horizontal axis indicates time, in (a) the vertical axis indicates voltage, in (b) the vertical axis indicates current, and in (c), the vertical axis indicates reference current.

  In the first step, when the rectangular wave voltage shown in FIG. 10A is applied to the coil 5, the current flowing through the coil 5 corresponds to the time constant determined by the inductance L and resistance as shown in FIG. 10B. A rise occurs.

  Next, the second step will be described. The current detection unit 12 detects the current flowing through the coil 5 and outputs a signal to the time measurement unit 15 when the current value has changed by a predetermined current change amount Δil, Δih from the time of applying the rectangular wave voltage. .

  The time measurement unit 15 receives a signal from the current detection unit 12 and measures a time tl taken for the current to change by Δil and a time th taken for the change by Δih, respectively. Information on the time tl and the time th, which are measurement values obtained by the time measurement unit 15, is input to the comparison unit 17 of the position detection unit 16c.

  Next, the third step will be described. In the comparison part 17, each measured value is compared with the reference current obtained from the coil model 25 shown in the 1st table 20a and FIG.10 (c), and the position of the needle | mover 6 is calculated | required.

  Next, how to determine the position of the mover 6 in the position detection unit 16c in the third step will be described.

  First, the coil model 25 will be described. The coil circuit equation can be generally expressed by the following equation 1, where E is the voltage applied to the coil, R is the resistance of the coil, i is the current flowing through the coil, and L is the inductance of the coil.

  As the coil model 25, the following equation 2 which is a transfer function from the voltage E applied by the coil obtained from equation 1 to the current i flowing through the coil is used.

  At this time, as the resistor R, a value obtained from an applied voltage when a DC voltage is applied before applying a rectangular wave voltage and a current flowing through the coil 5 at that time is used.

  Next, how to determine the value used as the inductance L in Equation 2 will be described. The comparison unit 17 compares the time th = tha, which is the measured value obtained by the time measuring unit 15, until the current changes by Δih, with the first table 20a shown in FIG. It can be seen that 6 exists at x = Pa = 0 or x = Pc.

  The comparison unit 17 provides the coil model 25 with information on the inductance L when the mover 6 is present at x = Pc where no magnetic saturation occurs, among the two obtained points, x = Pa = 0 and x = Pc. Output. This is because the magnetic field is not saturated and the inductance L has no current dependency and is constant.

  The coil model 25 receives the information on the inductance L output from the comparison unit 17 and adopts the value of the inductance L.

  A reference current waveform as shown in FIG. 10C is obtained from the coil model 25 in which the inductance L is determined in this way. Then, the coil model 25 outputs the time trl required for the reference current to change by Δil and the time trh required for the change of Δih to the comparison unit 17, respectively.

  FIG. 11 is a diagram illustrating a waveform of a current flowing through the coil 5 and a reference current waveform obtained from the coil model 25 according to the third embodiment of the present invention. FIG. 11A shows the mover 6 at x = Pa = 0. FIG. 5B is a diagram illustrating a case where the movable element 6 exists at x = Pc. In (a) and (b), the horizontal axis indicates time, and the vertical axis indicates the amount of current change. The waveform of the current flowing through the coil 5 is indicated by a solid line, and the reference current waveform obtained from the coil model 25 is indicated by a broken line.

  When x = Pa = 0 where magnetic saturation occurs, the time constant at the rising edge of the current changes every time depending on the value of the current. However, when x = Pc where magnetic saturation does not occur, the time constant is constant. Since the inductance L of the coil model 25 is set to be equal to the inductance L of the coil 5 when the movable element 6 exists at x = Pc, as shown in FIG. 11A, x = Pa = When the mover 6 exists at 0, the current waveform flowing through the coil 5 and the reference current waveform obtained from the coil model 25 do not match. That is, the time th required for the current flowing through the coil 5 to change by Δih and the time trh required for the reference current obtained from the coil model 25 to change by Δih coincide, but the current flowing through the coil 5 changes by Δil. The time tl taken until the reference current and the time trl taken until the reference current obtained from the coil model 25 changes by Δil do not match.

  On the other hand, as shown in FIG. 11B, when the mover 6 is present at x = Pc, the current waveform flowing through the coil 5 matches the reference current waveform obtained from the coil model 25. That is, th = trh and tl = trl.

  Therefore, the comparison unit 17 can determine the air gap x, that is, the position of the mover 6 by comparing th and trh and tl and trl.

  In the third embodiment of the present invention, since the configuration is as described above, a value actually measured before the operation of the position detection device 1c can be applied as the resistance R of the coil used in the coil model 25. Can respond to environmental changes and secular changes.

Embodiment 4 FIG.
FIG. 12 is a block diagram showing a configuration of a position detection apparatus 1d according to Embodiment 4 of the present invention. 12, the same reference numerals as those in FIG. 3 denote the same or corresponding components, and the description thereof is omitted. This embodiment differs from the first embodiment of the present invention in that the measurement is performed both at the rising edge and the falling edge of the current flowing through the coil 5 when the rectangular wave voltage is applied in the second step, and the second table 21a is omitted. Yes.

  Next, the operation of the position detection device 1d having such a configuration will be described. Here, a case will be described in which the position of the movable element 6 is obtained when the movable element 6 exists in either x = Pa = 0 or x = Pc in FIG.

  FIG. 13 is a diagram illustrating voltage and current waveforms when a rectangular wave voltage is applied to the coil 5 according to the fourth embodiment of the present invention, and (a) is a diagram illustrating a voltage waveform applied to the coil 5; (B) is a diagram showing a waveform of a current flowing through the coil 5, (c) is a diagram showing a rising waveform of a current flowing through the coil 5, and (d) is a diagram showing an inverted waveform of a falling waveform of the current flowing through the coil 5. is there. In (a) to (d), the horizontal axis represents time, in (a) the vertical axis represents voltage, and in (b) to (d), the vertical axis represents current.

  In the first step, when the rectangular wave voltage shown in FIG. 13 (a) is applied to the coil 5, the current flowing in the coil 5 rises according to the time constant determined by the inductance L and resistance, as shown in FIG. 13 (b). A fall occurs.

  Next, the second step will be described. The current detection unit 12 detects the current flowing through the coil 5 and outputs a signal to the time measurement unit 15 when the current value has changed by a predetermined current change amount Δil, Δih from the time of applying the rectangular wave voltage. . Further, a signal is output to the time measuring unit 15 when the current value changes by the current change amounts Δil and Δih defined in advance from the start of the fall of the current flowing through the coil 5.

  The time measurement unit 15 receives the signal from the current detection unit 12 and sets the time tul taken until the current changes Δil and the time tuh taken until the Δih change at the rise of the current flowing through the coil 5, respectively. taking measurement. Further, at the fall of the current flowing through the coil 5, the time tdl required for the current to change by Δil and the time tdh required for the change of Δih are measured. Information on time tul and time tuh, time tdl and time tdh, which are measurement values obtained by the time measurement unit 15, is input to the comparison unit 17 of the position detection unit 16d.

  In the third step, the comparison unit 17 compares the measurement values with the first table 20a and the measurement values to determine the position of the mover 6.

  Next, how to obtain the position of the mover 6 in the position detection unit 16d in the third step will be described. By comparing the time tuh = tha required for the current to change Δih at the time of rise, which is a measurement value obtained by the time measurement unit 15, by comparing with the first table 20 a shown in FIG. 7A in the comparison unit 17. It can be seen that the mover 6 exists at x = Pa = 0 or x = Pc.

  FIG. 14 is a diagram showing a rising waveform and a falling waveform of the current flowing in the coil 5 according to the fourth embodiment of the present invention, and FIG. 14 (a) is a diagram showing a case where the mover 6 exists at x = Pa = 0. (B) is a figure which shows the case where the needle | mover 6 exists in x = Pc. In (a) and (b), the horizontal axis indicates time, and the vertical axis indicates the amount of current change. The rising waveform is indicated by a solid line, and the falling waveform is indicated by a broken line.

  When x = Pa = 0 in which magnetic saturation occurs, the inductance L of the coil 5 decreases as the flowing current increases, as shown in FIG. Therefore, the inductance L at the rising edge decreases as the current increases, but the inductance L at the falling edge increases as the current decreases. That is, since the change in the inductance L is different between the rising time and the falling time, the rising waveform and the falling waveform do not match as shown in FIG. Therefore, even if tuh = tdh, tul and tdl do not match. Even if tul = tdl, tuh and tdh do not match.

  On the other hand, as shown in FIG. 14B, when the mover 6 is present at x = Pc, magnetic saturation does not occur, the inductance L is constant, and the rising waveform and the falling waveform match. That is, tuh = tdh and tul = tdl.

  As described above, the comparison unit 17 compares tuh and tdh and tul and tdl to determine whether or not magnetic saturation occurs. Therefore, the air gap x, that is, the position of the movable element 6 can be obtained from the comparison result and the comparison result between tuh and the first table 20a.

  In the fourth embodiment of the present invention, the configuration as described above does not require a plurality of tables indicating the relationship between the measured value and the air gap x, and only the first table 20a is required, and the coil model 25 is also required. do not do. Therefore, the position of the mover 6 can be uniquely determined with a simple configuration even when magnetic saturation occurs.

  In the fourth embodiment of the present invention, the time taken for the current to change Δih at the time of rising is compared with the first table 20a, so that the mover 6 becomes x = Pa = 0 or x = Pc. Sought to exist. However, the present invention is not limited to this, and other measured values such as ul, tdh, and tdl may be used. When other measurement values are used, a table corresponding to the measurement values to be used may be provided.

  The first to fourth embodiments of the present invention have been described above. These configurations described in the first to fourth embodiments of the present invention can be combined with each other.

DESCRIPTION OF SYMBOLS 1a-1d Position detection apparatus 2 Electromagnetic actuator 5 Coil 6 Movable element 7 Power supply 12 Current detection part 15 Time measurement part 16a-16d Position detection part 20a, 20b 1st table 21a, 21b 2nd table 25 Coil model

Claims (10)

A method for detecting the position of a mover of an electromagnetic actuator comprising a coil and a mover,
A first step of applying a varying voltage to the coil;
A second step of measuring a rising or falling state of the current flowing in the coil caused by application of the variable voltage, a plurality of times during the rising or falling;
A third step of determining the position of the mover by comparing a plurality of measurement values obtained in the second step with a reference measurement value or a calculated value, respectively;
The position detection method of the needle | mover of an electromagnetic actuator provided with this.   2. The second step is characterized in that the time taken for the current value to change by a predetermined amount after the rise or fall of the current flowing in the coil starts is measured for each of the plurality of predetermined amounts. For detecting the position of the mover of the electromagnetic actuator.   2. The second step is characterized in that the amount of current change from when the rising or falling of the current flowing through the coil starts until a predetermined time elapses is measured after each of the plurality of predetermined times elapses. A method for detecting the position of a mover of an electromagnetic actuator.   The measurement value used as a reference in the third step forms a plurality of tables showing the relationship between the measurement value obtained in the second step and the position of the mover. The method for detecting the position of the mover of the electromagnetic actuator according to any one of claims 3 to 4.   The calculation value used as a reference in the third step was obtained under the same conditions as those in the first step and the second step in the coil model set to the same inductance as that of the coil when the mover is present at a predetermined position. The method for detecting a position of a mover of an electromagnetic actuator according to any one of claims 1 to 3, wherein the position is a plurality of calculated values. In the second step, both the rise and fall of the current flowing in the coil are measured,
The plurality of measurement values to be compared in the third step are a plurality of measurement values obtained during the rise or a plurality of measurement values obtained during the fall. At least one table showing the relationship between the measurement value obtained during the rise or the measurement value obtained during the fall and the position of the mover, and the plurality of measurements obtained during the fall The method for detecting a position of a mover of an electromagnetic actuator according to any one of claims 1 to 3, wherein the value is a value or a plurality of measured values obtained during the rise. A position detection device for a mover of an electromagnetic actuator comprising a coil and a mover,
A power supply for applying a variable voltage to the coil;
A current detection unit for detecting a current flowing in the coil;
A time measuring unit for measuring a time from the start or fall of the current flowing in the coil caused by application of the variable voltage; and
A position detection unit for obtaining a position of the mover by comparing a plurality of measurement values obtained by the current detection unit or the time measurement unit with a measurement value or a calculation value serving as a reference;
A position detecting device for a mover of an electromagnetic actuator comprising:   The position detection unit includes a plurality of tables indicating the relationship between the measurement value obtained by the current detection unit or the time measurement unit and the position of the mover, and compares the plurality of measurement values with the plurality of tables. The position detecting device for a mover of an electromagnetic actuator according to claim 7, wherein the position of the mover is obtained.   The position detection unit includes a coil model set to the same inductance as that of the coil when the mover is present at a predetermined position, and a plurality of measured values obtained from the current detection unit or the time measurement unit and the coil model 8. The position detecting device for a mover of an electromagnetic actuator according to claim 7, wherein the position of the mover is obtained by comparing with a plurality of calculated values obtained.   The position detection unit is a current detection unit or a time measurement unit, and at least shows a measurement value obtained during the rise of the current flowing through the coil or a relationship between the measurement value obtained during the fall and the position of the mover. It has one table, and it is movable by comparing the measured value with the table and comparing a plurality of measured values obtained during the rising and a plurality of measured values obtained during the falling. 8. The position detecting device for a mover of an electromagnetic actuator according to claim 7, wherein the position of the child is obtained.

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