JP4443280B2 - Solenoid plunger position detection device, solenoid valve, and direction switching valve - Google Patents

Description

  The present invention relates to a solenoid plunger position detection device, an electromagnetic valve, and a direction switching valve.

  As this kind of solenoid plunger position detecting device and method, there is one provided with a position sensor for monitoring the position of the plunger. This position sensor utilizes the fact that the leakage flux of the coil varies depending on the position of the plunger, and has a mechanism in which the reed switch is opened and closed by the leakage magnetic flux that changes depending on the position of the plunger. However, in order to attach the position sensor of this hand to the solenoid, the position of the position sensor must be finely adjusted due to variations in its characteristics, and the plunger position may not always be detected accurately.

  Therefore, there is a proposal of a plunger position detection apparatus and method that eliminates the position sensor that is difficult to adjust. The plunger position detecting device and method includes, for example, a coil, a plunger inserted in the coil, a drive circuit for driving the plunger, and a resonance circuit including a pulse circuit used for detecting the plunger position. It is configured as a self-holding solenoid (latch solenoid), and when detecting the plunger position, the changeover switch switches the connection between the coil and the drive circuit, and the coil and the resonance circuit are connected. A voltage of a predetermined frequency is loaded on the coil with a pulse signal generated by the circuit, a resonance current is generated in the resonance circuit, and this resonance current is converted into a voltage by a detection resistor.

  The position of the plunger is detected from the voltage value converted by the detection resistor.

  That is, in the conventional plunger position detecting device and method, when the position of the plunger with respect to the coil changes, the inductance of the coil changes. Therefore, the change in the resonance condition due to this change in inductance is used.

  The change in the resonance condition can be grasped by monitoring the voltage generated by the resonance current, and the plunger position can be detected. That is, a change in coil inductance is detected to detect an abnormality such as a solenoid.

Also, in this device, a comparator having a threshold value for determining the position of the plunger is compared with the detected voltage, and the threshold value is compared. It can be detected whether or not there is (see Patent Document 1).
Japanese Patent Laid-Open No. 11-67536 (column of embodiment of the invention, FIG. 1)

  However, the above-described plunger position detecting device and method are advantageous in that a position sensor that is difficult to adjust, such as an attachment position, is not necessary, but there is a possibility that it may be pointed out that the following problems may be caused.

  Although the above-described plunger position detection device and method are effective for a self-holding solenoid, there is a possibility that a solenoid other than the self-holding solenoid does not hold. That is, except for the self-holding solenoid, when the drive circuit is switched to the resonance circuit, the attractive force of the coil disappears, and the plunger returns to the non-energized position. An abnormality in the state where the plunger is driven cannot be detected.

  In other words, in order to detect the plunger position, a position sensor is not necessary, but in order to measure coil inductance, it is necessary to switch from the drive circuit to the resonance circuit, and only the plunger position can be detected when the solenoid is not used. Therefore, the plunger position cannot be detected while the solenoid is being used, that is, while the plunger is being driven.

  Therefore, the present invention was devised to improve the above-described problems, and has an object to make it possible to detect the position of the plunger in the solenoid even when the solenoid is in use without requiring a position sensor. To do.

In order to achieve the above-described object, the problem-solving means of the present invention includes a pair of coils arranged in series and a plunger inserted into the coils, and excites any one of the coils. In the plunger position detecting device of the solenoid that can attract the plunger and drive the plunger to the excited coil side, the centering means for centering the plunger to the neutral position between the coils, and the coil by the pulse voltage or the pulse current Current generated by the induced electromotive force or induced electromotive force generated in the non-excited coil induced by the excited coil when the plunger is driven by exciting the coil with a pulse voltage or a pulse current. The position of the plunger is detected based on the above .

In order to achieve the above object, another problem-solving means of the present invention includes a pair of coils arranged in series and a plunger inserted into these coils, and any one of the above coils. Solenoid valve having a solenoid that attracts the plunger by exciting one and drives the plunger to the excited coil side, and a valve whose opening area changes due to the movement of the valve connected to one end of the plunger And a centering means for centering the plunger at a neutral position between the coils and an excitation means for exciting the coil with a pulse voltage or a pulse current, when the valve body is driven by exciting the coil with the pulse voltage or the pulse current. , Based on the induced electromotive force generated in the non-excited coil induced by the excited coil or the current generated by the induced electromotive force. Detecting the position of the valve element Te.

Furthermore, in order to achieve the above object, still another problem solving means of the present invention comprises a pair of coils arranged in series and a plunger inserted into these coils, and any one of the above coils. By energizing one of them, the plunger is attracted and the plunger can be driven to the excited coil side, the valve case connected to the solenoid, the valve case is slidably inserted, and the plunger Excitation means for exciting a coil with a pulse voltage or a pulse current in a direction switching valve having a spool connected to one end and a centering means for centering the plunger at a neutral position between the coils. When the spool is driven by exciting the coil with a pulse voltage or pulse current, And detecting the spool position based on the current generated by the induced electromotive force or induced electromotive force generated in the non-excitation of the coil induced by the coil.

According to the present invention, since the induced electromotive force generated in the non-excitation side coil is detected when detecting the position of the plunger, the valve body, or the spool (hereinafter referred to as the plunger), the solenoid is used, that is, the plunger is driven. However, the position of the plunger or the like can be detected. That is, it is possible to detect the position of the plunger or the like at the time of driving that could not be detected conventionally. Further, no position sensor is required, and the position of the plunger or the like can be continuously grasped with high accuracy. Furthermore, since the coil is excited using a pulse voltage or a pulse current, it is possible to detect the position of the valve body or the spool by pulling the position of the plunger while keeping the plunger in a certain position. That is, while the voltage or current applied to the excitation side coil is constantly changed, the plunger can be held at a fixed position, and the induced electromotive force of the other non-excitation side coil is caused by the magnetic flux change of the excitation side coil. Since an induced electromotive force can be generated, the position of the plunger can be detected while keeping the position of the plunger at a constant position. Therefore, it is possible to grasp not only that the plunger is driven but also the driving situation. In addition, since the plunger is centered, when the plunger is maintained in the neutral position, the direction switching valve is not in the driven state, so the position of the plunger or the like can be detected alternately by both coils. By detecting the position of the plunger or the like alternately with the two coils, the reliability of position detection is improved. Furthermore, by monitoring the change in the induced electromotive force of the non-excitation coil, it is possible to detect the direction of movement of the plunger and the like. It is possible to detect whether the movement itself is abnormal.

  Hereinafter, the present invention will be described with reference to the drawings. FIG. 1 is a conceptual diagram of a direction switching valve in the first embodiment. FIG. 2 is a diagram showing the relationship between the stroke of the plunger and the inductance of the coil. FIG. 3 is a diagram showing a waveform of the induced electromotive force of the non-excitation side coil when the plunger is attracted. FIG. 4 is a diagram showing a waveform of the induced electromotive force of the non-excitation coil when the plunger is in the neutral position. FIG. 5 is a conceptual diagram of a solenoid valve according to the second embodiment. FIG. 6 is a conceptual diagram of a plunger position detection device in the third embodiment.

  The plunger position detection device in the first embodiment is embodied in a directional switching valve, and the directional switching valve has a bottomed cylindrical valve case 1 and an opening of the valve case 1 as shown in FIG. A hollow coil case 5 connected to the part, a spool 11 slidably inserted into the valve case 1, a pin 12 in contact with the spool 11, and a plunger 13 fitted to the outer periphery of the pin 12 1 and the biasing spring 14 interposed between the left end in FIG. 1 of the spool 11 and the left inner surface in FIG. 1 of the valve case 1, the right end surface in FIG. 1 of the pin 12, and the right inner surface in FIG. And a pair of coils 7, 8 fixed in series in the coil case 5 so as to face the plunger 13, and so-called push-pull type direction switching. It is configured as a valve.

  In addition, one end of each of the coils 7 and 8 is connected to the control unit 30 via PWM (Pulse Width Modulation) circuits 20 and 21 and switching elements 22 and 23, and voltage conversion means for converting an AC voltage into a DC voltage. It is connected to the control unit 30 through rectifier circuits 25 and 26 and smoothing circuits 27 and 28 as VH. On the other hand, the other ends of the coils 7 and 8 are grounded.

  In the configuration of the direction switching valve in the present embodiment, the solenoid is constituted by a plunger 13, a pair of coils 7 and 8, and biasing springs 14 and 15 as centering means.

  In the following, each part will be described in detail. The valve case 1 is provided with five ports 160, 161, 162, 163, and 164. For example, the port 160 and the port 161 have one upstream flow path ( Port 162 is connected to another upstream flow path (not shown), port 163 is connected to one downstream flow path (not shown), and port 164 is downstream. It is connected to another flow path (not shown) on the side.

  Furthermore, the spool 11 is formed in a cylindrical shape, and four large-diameter blocking portions 111, 112, 113, and 114 that are in sliding contact with the inner periphery of the valve case 1 are formed on the outer peripheral side. Further, the spool 11 is urged to the right in FIG. 1 by the urging spring 14 from the left end side, and further urged to the left in FIG. 1 by the urging spring 15 through the pin 12 from the right end side of the spool 11. Yes.

  When the spool 11 is in the neutral position, that is, when the balance of only the biasing springs 14 and 15 is maintained without applying the coils 7 and 8, the blocking portion 112 and the blocking portion 113 of the spool 11 are respectively connected to the port. The ports 163 and 164 are blocked while facing the port 163 and the port 164.

  That is, in this case, the direction switching valve takes a blocking position that blocks the communication between the flow paths (not shown). That is, in this case, the centering means for centering the plunger 13 and the spool 11 to the neutral position is the urging springs 14 and 15.

  On the other hand, in a state where a current is applied to the coil 7, the plunger 13 is attracted to the coil 7, and the energizing spring 15 is compressed by the attraction force, and at the same time, the energizing spring 14 expands to cause the spool 11 to move in FIG. Move to the right. Then, the blocking unit 113 of the spool 11 opens the port 164 and the blocking unit 112 also opens the port 163.

  Since the port 164 and the port 162 communicate with each other, and the port 163 and the port 160 communicate with each other, one upstream channel (not shown) and one downstream channel (not shown) are connected. When the coil 8 is applied to the communication position, the plunger 13 is connected to the coil 8 in a communication position where the other flow path (not shown) on the upstream side and the other flow path (not shown) on the downstream side communicate with each other. The biasing spring 14 is compressed by the suction force, and at the same time, the biasing spring 15 extends to move the spool 11 to the left in FIG.

  Then, the blocking unit 113 of the spool 11 opens the port 164 and the blocking unit 112 also opens the port 163. Therefore, the port 164 and the port 161 communicate with each other, and the port 163 and the port 162 communicate with each other, so that one upstream channel (not shown) and another downstream channel (not shown) are connected. The communication position is a communication position for communicating another upstream flow path (not shown) and one downstream flow path (not shown). That is, the direction switching valve of the present embodiment is configured as a three-position four-port direction switching valve.

  Furthermore, one end of the coil 7 is connected to the output terminal side of the control unit 30 via the switching element 22 and the PWM circuit 20 as described above, and the input of the control unit 30 via the rectifier circuit 25 and the smoothing circuit 27. It is connected to the terminal side and the other end is grounded. Similarly, one end of the coil 8 is connected to the output terminal side of the control unit 30 via the switching element 23 and the PWM circuit 21, and is connected to the input terminal side of the control unit 30 via the rectifier circuit 26 and the smoothing circuit 28. The other end is grounded. The switching elements 22 and 23 may be any element that performs a switching operation by a pulse signal generated by the PWM circuits 20 and 21. Specifically, for example, a field effect transistor such as a transistor, FET, or MOSFET may be used. it can.

  Further, the switching elements 22 and 23 are supplied with a voltage from a separately provided power source Vcc, and can perform a predetermined switching operation by the pulse signals of the PWM circuits 20 and 21 to excite the coils 7 and 8, respectively. It has become.

  Note that known circuits may be used for the PWM circuits 20 and 21. In addition, a continuous modulation system such as a PAM (Pulse Modulation) circuit, a PPM (Pulse Position Modulation) circuit, a PNM (Pulse Number Modulation) circuit, or the like. The discontinuous modulation method may be adopted. Furthermore, from the viewpoint of exciting the coil using a pulse voltage or pulse current, a pulse generation circuit such as a multivibrator may be used in addition to the pulse modulation circuit.

  In addition, as described above, the excitation means for generating a pulse voltage or a pulse current to excite the coil are the PWM circuits 20 and 21, the switching elements 22 and 23, and the power source Vcc.

  As the rectifier circuits 25 and 26 and the smoothing circuits 27 and 28, known circuits may be used.

Further, the control unit 30 only needs to be able to operate the direction switching valve by exciting the coils 7 and 8 and process the voltage signal sent from the smoothing circuits 27 and 28. Is composed of a computer system comprising a storage device such as a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM, a crystal oscillator, and a bus line connecting these, a plunger 13 of the direction switching valve, and then the plunger 13 An arithmetic processing procedure used for specifying the position of the spool 11 connected to the control signal and a control signal output procedure for supplying voltage and current to the coils 7 and 8 are stored in advance in a ROM or other storage device as a program. .

  That is, the control unit 30 includes a plurality of input terminals and output terminals (not shown), and PWM circuits 20 and 21 and a smoothing circuit 27 that drive the direction switching valve with these output terminals by signal lines (not shown). , 28, the position of the spool 11 can be detected while the control unit 3 controls the direction switching valve.

  Now, the direction switching valve is configured as described above, and the operation of this direction switching valve will be described.

  First, the valve function of the direction switching valve will be described. As described above, when one of the coils 7 and 8 is excited, the plunger 13 moves to one of the left and right in FIG. 1 is also moved to either the left or right side in FIG. 1, and the flow path can be switched. If neither of the coils 7 and 8 is excited, the spool 11 is neutralized by the biasing springs 14 and 15. Each channel is blocked while maintaining the position. For example, when applying the coil 7, the control unit 30 causes the switching element 23 to perform a switching operation via the PWM circuit 21. Therefore, in this case, a voltage is applied from the power source Vcc to the coil 7, and the coil 7 is excited. The control unit 30 can control the effective current for exciting the coils 7 and 8 by adjusting the pulse modulation of the PWM circuits 20 and 21. By using the PWM circuits 20 and 21, the plunger 13 can be controlled. In the initial stage of movement, the On duty ratio is increased to improve the responsiveness, and after the plunger 13 is attracted to the coil 7, it can be lowered to an On duty ratio capable of maintaining a suction force sufficient to hold the plunger 13. Therefore, it is possible to save power by preventing unnecessary heat generation of the coil.

  On the other hand, when the coil 8 is excited, the control unit 30 causes the PWM circuit 20 to generate a pulse signal and cause the switching element 22 to perform a switching operation.

  When the coils 7 and 8 are not excited, the control unit 30 prevents the switching elements 22 and 23 from being turned on. Accordingly, no voltage is applied from the power source Vcc to the coils 7 and 8, the coils 7 and 8 are in a non-excited state, and the spool 11 is kept in a neutral state.

  Subsequently, in order to detect the plunger position, for example, when the coil 7 is excited, the control unit 30 determines based on the induced electromotive force generated in the non-excited coil 8.

  First, the control unit 30 excites the coil 7 of the direction switching valve according to the above procedure. Then, since the excitation of the coil 7 is performed through the switching element 23 driven by the PWM circuit 21, the voltage applied to the coil 7 is constantly changing. In the plunger position detection method, this is an excitation step.

  That is, the coil 7 is excited transiently or at a certain place or with a modulating frequency, and the magnetic field produced by the coil 7 also changes. At that time, since the flux linkage changes in the non-excitation coil 8, an induced electromotive force is generated due to the change.

  The induced electromotive force generated in the coil 8 at this time is detected by connecting one end of the coil 8 to the control unit 30. The induced electromotive force is an AC voltage, and is converted into a DC voltage by the rectifier circuit 25 and the smoothing circuit 27 described above, and this DC voltage is input to the control unit 30 as a signal. In the plunger position detection method, the detection step is to detect the AC voltage described here, and the conversion to the DC voltage corresponds to the conversion step.

  Here, the change in the inductance of the coil 7 will be described. As shown in FIG. 2, the inductance of the excitation side coil 7 and the stroke amount of the plunger 13 are the same as the inductance of the excitation side coil 7. Proportional. That is, as the coil 7 attracts the plunger 13 and the plunger 13 penetrates into the coil 7 deeper, the magnetic flux density increases and the inductance increases. The induced electromotive force increases as the coil inductance increases.

  From the relationship between the inductance and the plunger position, the control unit 30 can detect the plunger position from the magnitude of the induced electromotive force.

  The induced electromotive force that is output at this time is an alternating voltage, and in the state where the plunger 13 is attracted, the plunger 13 is attracted in the direction away from the non-excitation side coil 8, so that the waveform shown in FIG. If the neutral position is maintained even if the plunger 13 excites the coil 7 for some reason, a waveform as shown in FIG. 4 is obtained. Comparing the waveforms shown in FIGS. 3 and 4, it can be seen that the induced electromotive force generated in the non-excitation side coil 8 is larger when the plunger 13 is maintained at the neutral position.

  That is, since the magnitude of the induced electromotive force generated in the non-excitation side coil 8 varies depending on the plunger position, the position of the plunger 13 can be calculated backward from the magnitude or amplitude of the induced electromotive force or the magnitude of the current caused by the induced electromotive force. You can see where it is. Note that the input impedance of the voltage conversion means VH is sufficiently larger than the coil resistance, so that no switching means with the drive circuit is necessary.

  Specifically, the position of the plunger 13 is grasped as follows. The relationship between the magnitude of the DC voltage signal output from the smoothing circuit 27 and the DC voltage obtained by converting the plunger position and the induced electromotive force is previously mapped, and this map is stored in advance in the storage device of the control unit 30. Keep it.

  Then, the CPU of the control unit 30 is caused to calculate the plunger position by performing map calculation of the plunger position from the DC voltage obtained by converting the induced electromotive force generated in the non-excitation side coil 8. Although the position of the plunger can be easily detected by calculating the map, the plunger position may be calculated each time based on the relationship between the inductance of the coils 7 and 8 and the plunger position. This map calculation corresponds to a calculation step in the plunger position detection method.

  In addition, since the voltage conversion means VH is provided in this way, the induced electromotive force can be output as an analog level value to the control unit 30, so that an active inductance measurement circuit is not required and calculation for detecting the plunger position is performed. It becomes easy. Further, the plunger position can also be detected using an analog arithmetic circuit without mounting a CPU in the control unit 30.

  When the coil 8 is excited, the induced electromotive force generated in the non-excitation side coil 7 may be detected by the above procedure.

  In the present embodiment, since the induced electromotive force generated in the non-excitation side coil is detected when detecting the plunger position, the position of the plunger 13 can be detected while driving the plunger 13. That is, it is possible to detect the plunger position at the time of driving that could not be detected in the past. Further, no position sensor is required, and the position of the plunger 13 can be continuously grasped with high accuracy.

  Furthermore, since the coil is excited using a pulse voltage or a pulse current, it is possible to detect the position of the spool 11 by pulling the position of the plunger 13 while keeping the plunger 13 in a certain position. That is, while the voltage or current applied to the excitation side coil is constantly changed, the plunger 13 can be held at a constant position, and the induced electromotive force of the other non-excitation side coil is changed to the change in magnetic flux of the excitation side coil. Therefore, the position of the plunger 13 can be detected while keeping the position of the plunger 13 at a constant position. Therefore, it is possible to grasp not only that the plunger 13 has been driven but also the driving situation.

  The neutral position can be detected by exciting the coil so as to minimize the drive of the plunger 13 centered by the centering means.

  Since the PWM circuit is used, it is possible to generate induced electromotive force in the non-excitation side coil by a pulse signal with a constant period, etc., so the magnitude, amplitude, etc. of the induced electromotive force can be accurately monitored. However, when the PWM circuit is not used, the plunger position can be detected by transiently exciting the exciting coil to detect the induced electromotive force generated in the non-excited coil. . When the PWM circuit is not used, an induced electromotive force is generated in the non-excitation side coil even when power is cut off after the current is supplied to the coil. Of course.

  In addition, in the conventional plunger position detection device, the inductance detection is performed using a resonance circuit, and switching according to the frequency is necessary, and there is a concern that noise and abnormal noise are generated due to the resonance circuit and switching. In this embodiment, if there is no problem as a PWM circuit, problems such as noise and abnormal noise do not occur.

  Therefore, as described above, since the position of the plunger can be detected with high accuracy, it is possible to determine whether or not there is an abnormality in the direction switching valve based on the position of the plunger. Since it can be grasped accurately, if the direction switching valve is controlled using the plunger position as feedback, the controllability is improved. In addition, since the centering means is provided for detecting the abnormality of the direction switching valve, the two suction positions are provided even when the excitation to the coil is not performed proportionally, that is, even in the ON-OFF type excitation method. Since the positions of the three plungers and the spool in the neutral position can be detected, it is possible to detect an abnormality even if such an excitation method is employed.

  Further, since the spool 11 and the plunger 13 are centered, when the spool 11 and the plunger 13 are maintained at the neutral position, the direction switching valve is not in the driving state, so that the coils 7 and 8 are alternately used. Plunger position detection is possible, and the position detection reliability is improved by detecting the plunger position alternately with two coils. Furthermore, by monitoring the change in the induced electromotive force of the non-excitation coil, the direction of movement of the plunger 13 can also be detected. As a result, not only the plunger 13 of the direction switching valve cannot move but also the plunger 13 It is possible to detect whether the movement itself is abnormal.

  Incidentally, although it is a judgment of abnormality, in order to drive the plunger 13 or the spool 11, in order to drive the plunger 13 to a certain position, it is judged that the position of the plunger 13 does not follow the drive command for exciting one coil. That's fine. Specifically, for example, a threshold value is provided at the plunger position with respect to the drive command, and when it deviates from the threshold value, it may be determined as abnormal, and a generally used technique may be used. If only the abnormality is to be determined, it is only necessary to compare the magnitude of the induced electromotive force with the normal value (the magnitude of the induced electromotive force with respect to the drive command under a normal state). It is also possible to omit the operation unit such as and to make a determination using an analog operation circuit, so that the apparatus itself can be made inexpensive. In addition, when an abnormality is detected, a warning device that turns on a warning light or generates a warning sound can be provided separately to alert the user.

  In particular, the direction switching valve is a valve provided in the circuit of the hydraulic / pneumatic system and plays an important role in switching the flow path. As described above, accurate abnormality detection is possible. It can also be used for fail-safe such as stopping the operation of the system itself, and the safety of the hydraulic / pneumatic system can be increased.

  Next, the second embodiment shown in FIG. 5 will be described. The plunger position detection device of the second embodiment is embodied in an electromagnetic valve capable of adjusting the flow rate.

  In addition, about the member similar to 1st Embodiment, since description overlaps, only the same code | symbol is attached | subjected and the detailed description is abbreviate | omitted.

  As shown in FIG. 5, this electromagnetic valve is provided in a bottomed cylindrical valve case 41, a hollow coil case 5 connected to the opening of the valve case 41, the valve case 1, and the coil case 5. The valve body 42 movably inserted into the pair of coils 7, 8, the plunger 13 fitted to the outer periphery of the valve body 42, the right end surface of the valve body 42 in FIG. 5 and the coil case 5 in FIG. 5. An urging spring 45 interposed between the right inner surface and the urging spring 45 is provided. Further, one end of the coils 7 and 8 is connected to the control unit 30 via the PWM circuits 20 and 21 and the switching elements 22 and 23, respectively, as in the first embodiment. Is connected to the control unit 30 via amplifiers 46 and 47 and A / D converters 48 and 49, respectively, instead of the voltage conversion means VH. The other ends of the coils 7 and 8 are grounded.

  Hereinafter, each part will be described in detail. Two ports 410 and 411 are formed in the valve case 41, and the tip of the valve body 42 is urged by the urging spring 45 to close the port 410. Yes.

  When the valve body 42 is urged by the urging force of only the urging spring 45 without applying the coils 7 and 8 without applying the coils 7 and 8, the tip of the valve body 42, the taper at the left end in FIG. A portion (not shown) takes a blocking position where the port 410 is closed. On the other hand, when a current is applied to the coil 7, the plunger 13 is attracted to the coil 7, and the biasing spring 15 is compressed by the attracting force to move the valve element 42 to the right in FIG. 1. If it does so, the front-end | tip of the valve body 42 will leave | separate from the port 410, the port 410 will be opened, and the communication position which connects the port 410 and the port 411 will be taken. That is, the valve is composed of the valve case 41 and the valve body 42.

  The PWM circuits 20 and 21 are connected to the control unit 30 so that the pulse signals can be output not only to the switching elements 22 and 23 but also to the control unit 30. Furthermore, the amplifiers 46 and 47 and the A / D converters 48 and 49 connected to one ends of the coils 7 and 8 amplify the voltage signal as the induced electromotive force output from the non-excitation side coils 7 and 8, and The analog signal is converted into a digital signal and output to the control unit 30. As the amplifiers 46 and 47, a voltage follower circuit or an operational amplifier to which negative feedback is applied may be used.

  Then, the control unit 30 takes in the digital signal output from the A / D converters 48 and 49 using the pulse signal output from the PWM circuits 20 and 21 as a trigger at a predetermined timing at which the induced electromotive force is maximized, The obtained voltage signal is subjected to a map calculation in the same manner as in the first embodiment to calculate the position of the plunger 13 and thus the position of the valve body 42. That is, the PWM circuits 20 and 21, the amplifiers 48 and 49, and the A / D converters 48 and 49 constitute detection means. In the plunger position detection method, the procedure for detecting the induced electromotive force is as follows. This is a detection step.

  That is, in the present embodiment, it is of course possible to perform highly accurate plunger position detection as in the first embodiment, but in addition to the operational effects of the first embodiment, the voltage conversion means VH is provided. It is possible to detect the position of the plunger 13 without intervention.

  Therefore, it is not necessary to provide the voltage conversion means VH. Therefore, in the case of a vehicle, a calculation program for calculating the plunger position is stored in a control device originally provided in the hydraulic / pneumatic system, for example, an ECU mounted on the vehicle. If you keep it, system integration is possible.

  Furthermore, in the electromagnetic valve according to the present embodiment, the opening area of the port 410 can be changed depending on the position of the valve body 42. Therefore, when proportionally controlling the voltage or current applied to the coil 7, the valve body 42 is used. If the position is detected and feedback control is performed, precise flow rate control without variation can be performed.

  Furthermore, in the present embodiment, the coil 8 is provided only for detecting the position of the plunger 13 and thus the position of the valve body 42. However, the coil 8 is excited to induce the non-excitation side coil 7. If the electromotive force is detected, it is possible to accurately detect whether or not the return positions of the plunger 13 and the valve body 42 are normal. That is, in the first place, when the plunger 13 and the valve body 42 are in the return position, the valve body 42 is in contact with the opening end of the port 410 by the biasing spring 45. Thus, it is possible to grasp whether the port 42 is in contact with the port 410 and closes the port 410.

  Whether or not the valve element 42 is in the return position can be determined by monitoring only the induced electromotive force on the coil 8 side or by applying a weak voltage to the coil 7 as in the first embodiment. Although it cannot be determined, the reliability of position detection is increased by monitoring the induced electromotive force on the coil 7 side.

  Further, when the valve body 42 cannot be restored to the return position for some reason, the solenoid valve is kept in the communication position, so the coil 8 is excited to attract the plunger 13 and move the valve body 42. It is also possible to return to the blocking position.

  Incidentally, in the case of this embodiment, if the coil 8 side is always the non-excitation side, the PWM circuit 20 and switching element 22 on the coil 8 side, the amplifier 47 on the coil 7 side, and the A / D converter 49 may be omitted. Good.

  Although the valve body 42 is shown as a poppet type in the drawing, it may be a spool. In that case, a port may be provided on the side of the valve case 41. Further, in the case of a spool, centering means may be provided, and in that case, the effect of providing the centering means is also achieved.

  Finally, a third embodiment will be described. In the plunger position detecting device of the third embodiment, although the detailed configuration of the solenoid is not shown, it is the same as that of the second embodiment, and is different from the second embodiment in that the coil 7, That is, the control unit 30 monitors the voltage of the power source Vcc that excites 8. Specifically, as shown in FIG. 6, the voltage of the power supply Vcc is divided by voltage dividing resistors R1 and R2, and the divided voltage is read by the control unit 30 via the A / D converter 50. It is.

  As in the second embodiment, for example, when the coil 7 is excited, the plunger position is calculated by detecting the magnitude of the induced electromotive force of the non-excitation side coil 8 and performing calculation processing. At this time, the control unit 30 performs a correction operation using the voltage of the power supply Vcc.

  When the power supply Vcc is not functioning normally, that is, when the output voltage is not stable or the predetermined voltage cannot be output, the accurate voltage of the power supply Vcc, which is the excitation voltage value for exciting the coil, is controlled. Since it can be grasped by the unit 30, the induced electromotive force generated by the non-excitation coil is corrected based on this accurate voltage. Specifically, the non-excitation side coil to be output when the power source Vcc is normal by correcting the induced electromotive force generated by the non-excitation side coil by the ratio between the normal value of the power source Vcc and the accurate voltage value. The induced electromotive force is calculated and the map calculation is performed from the calculation result in the same manner as in the first or second embodiment, or the map itself is corrected by the ratio between the normal value of the power supply Vcc and the accurate voltage value. An accurate position of the plunger 13 is calculated by performing a map calculation from the induced electromotive force output from the non-excitation coil, or by performing a calculation each time with a correction without performing a map calculation.

  Therefore, in the third embodiment, since it is possible to detect the plunger position in consideration of the influence of the voltage change of the power supply Vcc, it is possible to detect the position of the plunger 13 more accurately. . That is, in the plunger position detecting means and method in the third embodiment, not only the same effects as in the second embodiment can be obtained, but also the deterioration of the plunger position detection accuracy can be prevented. When used for control, deterioration of control accuracy can be prevented. Since there is no need to install a circuit or the like for enabling a stable voltage supply to the power supply Vcc, it is simple and inexpensive.

  In the third plunger position detecting device and method, the power source Vcc is used in an environment where the power source Vcc is an alternator or a battery such as an automobile and the voltage is not stable due to the running state of the automobile or the aging deterioration. Can withstand.

  In each of the above-described embodiments, the position of the plunger, and thus the position of the valve body and the spool is detected by detecting the magnitude of the induced electromotive force generated in the non-excitation side coil. Alternatively, the current generated by the induced electromotive force may be detected, and the position of the plunger or the like may be detected from the magnitude of the current.

  This is the end of the description of the embodiment of the present invention, but the scope of the present invention is of course not limited to the details shown or described.

It is a conceptual diagram of the direction switching valve in 1st Embodiment. It is a figure which shows the relationship between the stroke of a plunger, and the inductance of a coil. It is a figure which shows the waveform of the induced electromotive force of the non-excitation side coil in the state by which the plunger was attracted | sucked. It is a figure which shows the waveform of the induced electromotive force of the non-excitation side coil in the state which has a plunger in a neutral position. It is a conceptual diagram of the solenoid valve in 2nd Embodiment. It is a conceptual diagram of the plunger position detection apparatus in 3rd Embodiment.

Explanation of symbols

1, 41 Valve case 5 Coil case 7, 8 Coil 11 Spool 12 Pin 13 Plunger 14, 15, 45 Biasing spring 20, 21 PWM circuit 22, 23 Switching element 25, 26 Rectifier circuit 27, 28 Smoothing circuit 30 Control unit 42 Valve body 46, 47 Amplifier 48, 49, 50 A / D converter 111, 112, 113, 114 Blocking unit 160, 161, 162, 163, 164, 410, 411 Port Vcc Power supply VH Voltage conversion means

Claims (18)

A pair of coils arranged in series and a plunger inserted into these coils are provided, and by exciting one of the coils, the plunger is attracted and the plunger is driven to the excited coil side. In a possible solenoid plunger position detecting device, a centering means for centering the plunger at a neutral position between the coils and an excitation means for exciting the coil with a pulse voltage or a pulse current are provided, and the coil is excited with the pulse voltage or the pulse current. When the plunger is driven, the position of the plunger is detected based on the induced electromotive force generated in the non-excitation coil induced by the excited coil or the current generated by the induced electromotive force. Position detection device. Voltage conversion means for converting an AC voltage into a DC voltage is provided, an induced electromotive force generated in a non-excitation coil is converted into a DC voltage by the voltage conversion means, and a plunger position is detected based on the DC voltage. The solenoid plunger position detecting device according to claim 1 . Detecting means for detecting the voltage value at the maximum amplitude of the induced electromotive force generated in the non-excited coil using the pulse signal generated by the exciting means as a trigger, and detecting the position of the plunger based on the voltage value The solenoid plunger position detecting device according to claim 1 . 4. The solenoid plunger position detecting device according to claim 1, further comprising calculating means for calculating a map of the position of the plunger. The solenoid plunger position detecting device according to any one of claims 1 to 4 , further comprising correction calculation means for correcting and calculating the position of the plunger based on an excitation voltage value for exciting the coil. A pair of coils arranged in series and a plunger inserted into these coils are provided, and by exciting one of the coils, the plunger is attracted and the plunger is driven to the excited coil side. a solenoid capable, in the electromagnetic valve having a valve opening area by movement of the valve body which is connected to one end of the plunger is changed, a centering means for centering the plunger in a neutral position between the coils, a pulse voltage or pulse An exciting means for exciting the coil with an electric current, and when driving the valve body by exciting the coil with a pulse voltage or pulse current, an induced electromotive force or induction generated in the non-excited coil induced by the excited coil A solenoid valve that detects the position of the valve body based on the current generated by the electromotive force . Voltage conversion means for converting AC voltage into DC voltage is provided, and induced electromotive force generated in the non-excitation coil is converted into DC voltage by the voltage conversion means, and the position of the valve body is detected based on the DC voltage. The electromagnetic valve according to claim 6 . Detecting means for detecting the voltage value at the maximum amplitude of the induced electromotive force generated in the non-excited coil using the pulse signal generated by the exciting means as a trigger, and detecting the position of the valve body based on the voltage value The electromagnetic valve according to claim 6 . The electromagnetic valve according to any one of claims 6 to 8 , further comprising calculation means for calculating a map of the position of the valve body. 10. The electromagnetic valve according to claim 6, further comprising correction calculation means for correcting and calculating the position of the valve body based on an excitation voltage value for exciting the coil. The electromagnetic valve according to claim 6, wherein flow rate control is performed based on a detection result of the valve body position. The solenoid valve according to any one of claims 6 to 11 , wherein whether or not there is an abnormality is detected based on a detection result of the valve body position. A pair of coils arranged in series and a plunger inserted into these coils are provided, and by exciting one of the coils, the plunger is attracted and the plunger is driven to the excited coil side. Possible solenoid, a valve case connected to the solenoid, a spool slidably inserted into the valve case and connected to one end of the plunger, and a centering means for centering the plunger in a neutral position between the coils In the direction switching valve that switches the flow path according to the position of the spool, it is provided with an excitation means for exciting the coil with a pulse voltage or pulse current. When the spool is driven by exciting the coil with the pulse voltage or pulse current, excitation is performed. Induced electromotive force or induction generated in a non-excited coil induced by a selected coil Directional control valve for detecting a spool position based on the current generated by the power. Voltage conversion means for converting an AC voltage into a DC voltage is provided, an induced electromotive force generated in a non-excitation coil is converted into a DC voltage by the voltage conversion means, and a spool position is detected based on the DC voltage. The direction switching valve according to claim 13 . Detecting means for detecting the voltage value at the maximum amplitude of the induced electromotive force generated in the non-excited coil using the pulse signal generated by the exciting means as a trigger, and detecting the spool position based on the voltage value. The direction switching valve according to claim 13 . The direction switching valve according to any one of claims 13 to 15 , further comprising calculation means for calculating a map of the position of the spool. The direction switching valve according to any one of claims 13 to 16 , further comprising correction calculation means for correcting and calculating the position of the spool based on an excitation voltage value for exciting the coil. 18. The direction switching valve according to claim 13, wherein whether or not there is an abnormality is detected based on a detection result of the spool position.

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