JP2009261140A - Electromagnetic proportional valve drive controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic proportional valve drive controller which is protected from excess current in a power short circuit. <P>SOLUTION: The electromagnetic proportional valve drive controller includes a signal generating means formed of a command value generating part 131, a duty ratio operating part 132 and a PWM signal generating part 133, an excitation current feeding switching element 113 conducting a coil of an electromagnetic proportional valve 114 in accordance with a signal and a current-voltage converter 117 converting an excitation current flowing in the electromagnetic proportional valve into a voltage and returning the voltage to the signal generating means as a detection voltage. The controller is also provided with an excess current interruption switching element 116 preventing the excess current from flowing into the controller and a latch element 119 inputting the detection voltage output from the current-voltage converter and turning off the excess current interruption switching element when a value of detection voltage becomes not less than a setting value for excess current fault detection. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electromagnetic proportional valve drive control device, and more particularly, to an electromagnetic proportional valve drive control device that can cope with a line short circuit failure and a power supply short circuit failure that occur in an electromagnetic proportional valve used in hydraulic control of a construction machine or the like.

  As a prior art of an apparatus for driving an inductive load such as an electromagnetic proportional valve provided in a hydraulic control apparatus such as a construction machine, there is a technique disclosed in Patent Document 1.

  FIG. 6 shows a configuration related to overcurrent limitation based on the inductive load driving device disclosed in Patent Document 1.

  6, reference numeral 601 denotes a block representing an arithmetic processing unit, 602 an electromagnetic proportional valve (corresponding to a solenoid) that is an inductive load, 603 a power supply that supplies a drive current to the electromagnetic proportional valve 602, and 604 an electromagnetic proportional valve. An exciting current feeding switching element that performs an on / off operation for adjusting the supply amount of the driving current, 605 is a block that represents an overcurrent limiting unit interposed between the power source 603 and the exciting current feeding switching element 604 , 606 is a load current circulating element arranged in parallel with the electromagnetic proportional valve 602.

  The arithmetic processing unit 601 includes a command value generation unit 611, a duty ratio calculation unit 612, a PWM signal generation unit 613, a failure determination unit 614, a failure protection unit 615, and an A / D conversion unit 616.

  The command value generator 611 outputs a command value that determines the operating state of the electromagnetic proportional valve 602. The duty ratio calculation unit 612 receives the command value, calculates the duty ratio, and outputs it. The PWM signal generation unit 613 generates a PWM signal having the duty ratio based on the duty ratio output from the duty ratio calculation unit 612. The A / D conversion unit 616 converts an analog signal related to the energization amount provided from the electromagnetic proportional valve 602 side into a digital value and provides the digital value to the failure determination unit 614. The failure determination unit 614 compares the signal related to the command value output from the command value generation unit 611 with the signal output from the A / D conversion unit 616 to determine whether there is a failure. A signal related to the determination output from the failure determination unit 614 is provided to the failure protection unit 615. The failure protection unit 615 outputs a signal for turning off the PWM signal to the duty ratio calculation unit 612 in order to protect the drive device when it is determined that the short circuit failure has occurred between the lines.

  The PWM signal output from the PWM signal generation unit 613 of the arithmetic processing unit 601 is input to the voltage conversion unit 621, converted to a required level voltage, and further input to the feedback circuit / PWM signal generation unit 622 in the next stage. The PWM signal output from the feedback circuit / PWM signal generator 622 is input to the exciting current feeding switching element 604 and controls its on / off operation. A current is supplied to the electromagnetic proportional valve 602 when the exciting current feeding switching element 604 is turned on. The current supplied to the electromagnetic proportional valve 602 flows to the ground 699 side, and is converted into a voltage signal by the current / voltage converter 623 on the way. The back electromotive force generated in the electromagnetic proportional valve 602 when the exciting current feeding switching element 604 is off is a load current provided between the ground side terminal of the current / voltage converter 623 and the input side terminal of the electromagnetic proportional valve 602. It is circulated to the input side of the electromagnetic proportional valve 602 via the recirculation element 606. The voltage signal output from the current / voltage converter 623 is amplified by the amplifier 624, and the voltage signal output from the amplifier 624 is input to the A / D converter 616 and the feedback circuit / PWM signal generator 622. Is done.

  The overcurrent limiting unit 605 includes a current / voltage converter 631 and an overcurrent limiting switching element 632. When the exciting current feeding switching element 604 is turned on and current flows from the power source 603 to the electromagnetic proportional valve 602, the current / voltage converter 631 converts the current value into a voltage value. The voltage value is input to the overcurrent limiting switching element 632. Based on the voltage value input from the current / voltage converter 631, the overcurrent limiting switching element 632 is supplied to the exciting current feeding switching element 604 when the voltage value exceeds a predetermined value that is an overcurrent. Block the PWM signal.

  Further, in a device for driving an inductive load, Patent Document 2 discloses a conventional power supply short-circuit protection circuit that protects a device when a cable or a terminal connecting an electromagnetic proportional valve and a current / voltage conversion means fails in a power supply short circuit. The described circuit is known.

  FIG. 7 shows a configuration equivalent to the power supply short circuit protection circuit disclosed in Patent Document 2.

  In FIG. 7, 720 is an arithmetic processing unit, 702 is an electromagnetic proportional valve (solenoid), 703 is a power source for supplying power to the electromagnetic proportional valve 702, and 704 is for adjusting the amount of drive current supplied to the electromagnetic proportional valve. Excitation current feeding switching element that performs on / off operation, 705 is an overcurrent limiting switching element, 706 is an overcurrent limiting resistor provided in parallel with the overcurrent limiting switching element, 707 is a current / voltage converter, Reference numeral 708 denotes a drive circuit that drives the exciting current feeding switching element 704 with a signal from the arithmetic processing unit, and 709 denotes an amplifier circuit that amplifies the voltage converted by the current / voltage conversion means 707.

  In the normal state, the drive circuit 708 simultaneously controls on / off of the exciting current feeding switching element 704 and the overcurrent limiting switching element 705 based on a command signal from the arithmetic processing unit 720.

  When the electromagnetic proportional valve 702 is turned on, the exciting current of the electromagnetic proportional valve 720 is supplied from the power source 703 to the exciting current feeding switching element 704, the electromagnetic proportional valve 702, the overcurrent limiting switching element 705, and the current / voltage converting means. 707.

  When a power supply short circuit to the apparatus occurs when the electromagnetic proportional valve 702 is turned on, overcurrent flows from the power supply 703 via the overcurrent limiting switching element 705 and the current / voltage conversion means 707. A detection voltage higher than normal generated by the overcurrent is detected by the arithmetic processing unit 720 from the current / voltage conversion unit 707 via the amplifier 709. The arithmetic processing unit 720 determines that the power supply is short-circuited based on the voltage detection exceeding the specified value. The arithmetic processing unit 720 turns off the exciting current feeding switching element 704 and the overcurrent limiting switching element 705 when a power supply short circuit failure occurs. When the overcurrent limiting switching element 705 is turned off, the current flows to the current / voltage conversion means 707 via the overcurrent limiting resistor 706, so that the current is limited and does not become an overcurrent. To prevent damage.

If a power supply short circuit occurs when the electromagnetic proportional valve 702 is turned off, the overcurrent limiting element 705 is turned off and is not energized. At this time, the current flows to the current / voltage conversion means 707 via the overcurrent limiting resistor 706, so that the current is limited to prevent the device from being damaged by the overcurrent.
JP 2002-176346 A JP 2007-97333 A

  In the inductive load driving device described in Patent Document 1, a power supply short-circuit such that the cable connecting the electromagnetic proportional valve 602 and the current / voltage converter 623 is short-circuited to the power supply 603 (FIGS. 2C and 2D described later). In this case, it is impossible to prevent an overcurrent from being applied to the device, and the drive device is damaged.

  In addition, when the failure protection unit 615 completely turns off the PWM signal to protect the device, there is no means for returning the operation of the device. Therefore, when the failure determination unit 614 makes an incorrect determination, the driving is resumed. Can not do it. Furthermore, there is a problem in that driving of the inductive load cannot be resumed even after recovery from the failure state.

  In the power supply short circuit protection circuit described in Patent Document 2, it is possible to protect the device when the power supply is short-circuited, which was a problem of Patent Document 1. However, in order to suppress the overcurrent, it is necessary to provide an overcurrent limiting resistor 706 in parallel with the overcurrent limiting switching element 705, which increases the number of parts and cost, and the overcurrent limiting resistor when overcurrent is limited. There is a problem of heat generation of 706.

  Further, it is necessary to control the overcurrent limiting switching element 705 in conjunction with the on / off control of the exciting current feeding switching element 704, which causes a problem that the processing in the arithmetic processing unit 720 becomes complicated.

  An object of the present invention is to provide an electromagnetic proportional valve drive control device capable of protecting the electromagnetic proportional valve drive control device when a power supply line or the like is short-circuited.

  In order to achieve the above object, an electromagnetic proportional valve drive control device according to the present invention is configured as follows.

  A first electromagnetic proportional valve drive control device (corresponding to claim 1) is provided between a power source and an electromagnetic proportional valve, and an excitation current feeding switching element for energizing a coil of the electromagnetic proportional valve according to a signal; An electromagnetic proportional valve drive control device comprising current / voltage conversion means for converting an excitation current flowing through an electromagnetic proportional valve into a voltage, and the electromagnetic proportional valve drive device by a short circuit of a power supply line or the like outside the electromagnetic proportional valve drive control device And an overcurrent cutoff switching element that cuts off the power supply from the electromagnetic proportional valve to the current / voltage conversion means when an overcurrent is applied.

  With such a configuration, when a power supply short circuit or line short circuit occurs outside the drive control device and an overcurrent is applied to the drive device, a current / voltage conversion is performed from the electromagnetic proportional valve by the overcurrent cutoff switching element. The power supply to the means can be cut off.

  A second electromagnetic proportional valve drive control device according to the present invention (corresponding to claim 2) is the first electromagnetic proportional valve drive control device, wherein the overcurrent cutoff switching element is an excitation current feeding switching element. It is characterized by being turned on in the normal state and turned off only when the overcurrent is interrupted without being related to the on / off state.

  According to the above configuration, the exciting current feeding switching element and the overcurrent cutoff switching element can be individually controlled, and the overcurrent cutoff switching element does not change except during the overcurrent cutoff. Circuits and arithmetic devices can be eliminated.

  The third electromagnetic proportional valve drive control device (corresponding to claim 3) is triggered by the detection voltage converted by the current / voltage conversion means when an overcurrent is generated in the second electromagnetic proportional valve drive control device. A latch element for controlling on / off of the overcurrent cutoff switching element is provided.

  As a result, the overcurrent cutoff switching element can be controlled without performing special arithmetic processing or the like.

  A fourth electromagnetic proportional valve drive control device (corresponding to claim 4) is the third electromagnetic proportional valve drive control device, wherein an on / off control signal to an overcurrent cutoff switching element accompanying the operation of the latch element is provided. It is characterized in that monitoring means is provided for monitoring the execution state of protection against overcurrent based on the ON / OFF control signal.

  Thereby, it is possible to easily grasp whether or not an overcurrent has occurred.

  A fifth electromagnetic proportional valve drive control device (corresponding to claim 5) receives a signal from the monitoring means in the fourth electromagnetic proportional valve drive control device, and the signal is in an execution state of protection against overcurrent. In some cases, there is provided a return processing means for generating an instruction signal for returning the latch element to the initial state in order to return the overcurrent cutoff switching element from the cutoff state to the energized state.

  Thereby, when it returns from an overcurrent state to a normal state, it can be made to return to an energized state automatically.

  The sixth electromagnetic proportional valve drive control device (corresponding to claim 6) receives the detection voltage converted by the current / voltage conversion means in the second electromagnetic proportional valve drive control device, and based on this detection voltage, The present invention is characterized in that arithmetic processing means is provided for determining whether or not current is generated and controlling on / off of the overcurrent cutoff switching element in accordance with the determination result.

  A seventh electromagnetic proportional valve drive control device (corresponding to claim 7) is the on / off control signal output from the arithmetic processing means to the overcurrent cutoff switching element in the sixth electromagnetic proportional valve drive control device. And monitoring means for monitoring the execution state of protection against overcurrent.

  An eighth electromagnetic proportional valve drive control device (corresponding to claim 8) is the seventh electromagnetic proportional valve drive control device, wherein a signal from the monitoring means is input, and the signal is in an execution state of protection against overcurrent. In this case, in order to return the overcurrent cutoff switching element from the cutoff state to the energized state, there is provided a return processing means for directly outputting a return signal to the overcurrent cutoff switching element.

  A ninth electromagnetic proportional valve drive control device (corresponding to claim 9) uses a switching element having an overheat output cutoff function as the overcurrent cutoff switching element in the first electromagnetic proportional valve drive control device. It is characterized by that.

  A tenth electromagnetic proportional valve drive control device (corresponding to claim 10) is the first to ninth electromagnetic proportional valve drive control device, wherein the electromagnetic proportional valve is provided in a hydraulic circuit of a construction machine. It is characterized by being.

  The present invention has the following effects.

  According to the first aspect of the present invention, when the overcurrent cutoff switching element provided between the electromagnetic proportional valve and the current / voltage converting means is turned off, the electromagnetic proportional is generated when a line short circuit failure or a power supply short circuit failure occurs. The overcurrent applied to the valve drive device can be prevented from flowing into the electromagnetic proportional valve drive device, and the electromagnetic proportional valve drive device can be protected.

  According to the second aspect of the present invention, since the overcurrent cutoff switching element can be controlled regardless of the on / off state of the exciting current feeding switching element, the circuit and arithmetic processing necessary for the control are facilitated. be able to.

  According to the third aspect of the present invention, since the overcurrent cutoff switching element can be controlled by using a simple latch element, for example, an arithmetic processing for protection is not required.

  According to the fourth aspect of the present invention, it is possible to detect the overcurrent protection state of the electromagnetic proportional valve drive control device by monitoring the state of the overcurrent cutoff switching element. As a result, it is possible to enhance the control of changing the electromagnetic proportional valve control and the vehicle body control based on the protection state, and to assist in identifying the failure location during maintenance.

  According to the present invention of claim 5, it is possible to automatically return from the protection state against overcurrent to the normal state. Thus, for example, when the device recovers from the failure state or when the failure is erroneously determined, the device can be quickly returned to the normal operation, and the reliability of the device can be improved.

  According to the sixth aspect of the present invention, it is possible to detect the abnormal state and control the switching element for overcurrent interruption by the arithmetic processing means, so that it is not necessary to add a special detection circuit for protection.

  According to the seventh aspect of the present invention, as in the fourth aspect, it is possible to detect the overcurrent protection state of the electromagnetic proportional valve drive control device by monitoring the state of the overcurrent cutoff switching element. It becomes. As a result, it is possible to enhance the control of changing the electromagnetic proportional valve control and the vehicle body control based on the protection state, and to assist in identifying the failure location during maintenance.

  According to the eighth aspect of the present invention, similarly to the fifth aspect, it is possible to automatically return from the protection state against the overcurrent to the normal state. Thus, for example, when the device recovers from the failure state or when the failure is erroneously determined, the device can be quickly returned to the normal operation, and the reliability of the device can be improved.

  According to the present invention of claim 9, the overcurrent cutoff switching element can be controlled by the overheat output cutoff function provided in the overcurrent cutoff switching element. No need to add.

  DESCRIPTION OF EMBODIMENTS Preferred embodiments (examples) of the present invention will be described below with reference to the accompanying drawings.

(First embodiment)
An embodiment of an electromagnetic proportional valve drive control device according to the present invention will be described with reference to FIGS. FIG. 1 shows the overall configuration of an electromagnetic proportional valve drive control device.

  In FIG. 1, 141 is a control device, 114 is an electromagnetic proportional valve that is a drive control target, and 112 is a power source that supplies a drive current to the electromagnetic proportional valve 114. 111 is an arithmetic processing unit, 113 is an exciting current feeding switching element that performs an on / off operation to adjust the amount of drive current supplied to the electromagnetic proportional valve 114, and 117 is a detection voltage for detecting the exciting current of the electromagnetic proportional valve 114. A current / voltage conversion element that converts the detected voltage into a voltage suitable for the arithmetic processing unit; and 115, a back electromotive force generated when the exciting current feeding switching element 113 is turned off. A load current recirculation element to be circulated, 116 is an overcurrent cutoff switching element for controlling the connection between the electromagnetic proportional valve 114 and the current / voltage converter 117 based on the signal, and 119 is a detection voltage of the current / voltage converter 117. Based on this, it is a latch element that generates an operation (control) signal to the overcurrent cutoff switching element 116.

  The arithmetic processing unit 111 is a microcomputer in the present embodiment, and as a functional element, a command value generation unit 131, a duty ratio calculation unit 132, a PWM signal generation unit 133, an A / D conversion unit 134, A detection voltage storage unit 135, a digital output 138, a digital input 137, a failure monitoring unit 136, and a recovery processing unit 139 are provided. These functional elements are realized by software.

  In the electromagnetic proportional valve drive control device according to the present embodiment configured as described above, for example, in the normal state shown in FIG. It is driven based on the on / off operation of the power supply switching element 113. The drive current I of the electromagnetic proportional valve 114 is converted to a voltage V by the current / voltage converter 117 and taken into the arithmetic processing unit 111 via the amplifier 118. The arithmetic processing unit 111 drives the electromagnetic proportional valve 114 based on the detected voltage V. That is, the duty ratio calculation unit 132 performs feedback calculation processing from the command value of the command value generation unit 131 and the detected voltage V, and outputs the duty ratio. The output duty ratio is supplied as a PWM signal from the PWM signal generation unit 133 to the exciting current feeding switching element 113 to drive the electromagnetic proportional valve 114.

  Next, a line short circuit failure and a power supply short circuit failure will be described with reference to FIGS. As shown by T1 in FIG. 2B, the return side line 150 (line connecting the electromagnetic proportional valve 114 and the overcurrent cutoff switching element 116) to the control device 141, the exciting current feeding switching element 113, and the electromagnetic proportionality. A phenomenon in which the line 151 connecting the valve 114 is short-circuited is called a line-to-line short-circuit failure. Further, as shown by T2 in FIGS. 2C and 2D, a phenomenon in which the power source 112 side and the return side line 150 are short-circuited is called a power source short-circuit failure.

  When a failure due to such a short circuit with the return side line 150 occurs, an overcurrent is applied to the return side line 150, and if this overcurrent continues to flow, the current / voltage converter 117 may be damaged.

  Next, an operation when an overcurrent occurs due to a line short circuit failure or a power supply short circuit failure at normal time will be described with reference to FIGS. In FIG. 3, the applied current I to the current / voltage converter 117, the detection voltage V, the operation signal S1 to the switching element 116 for interrupting overcurrent by the latch element 119, and the operation signal 111 are output to the latch element 119 The operations of the digital output signal D1 and the latch element 119 are shown in time series. The horizontal axis is the time axis, and shows the signals and behavior during normal operation, failure occurrence, protection operation, and return operation, respectively.

  In a normal (normal) operation indicated by reference numeral 401 in FIG. 3, an ON signal is output from the digital output 138 of the arithmetic processing unit 111 (FIG. 3D), and the latch element 119 is in an OFF state (FIG. 3E), That is, the state in which the digital output 138 and the overcurrent cutoff switching element 116 are connected is maintained. Therefore, an ON signal is supplied as the operation signal S1 to the overcurrent cutoff switching element 116 (FIG. 3C). The operation signal S <b> 1 supplied to the overcurrent cutoff switching element 116 is input to the failure monitoring unit 136 provided in the arithmetic processing unit 111 via the digital input 137. The overcurrent cutoff switching element 116 maintains the energized state between the electromagnetic proportional valve 114 side and the current / voltage converter 117 in a state where the ON operation signal S1 is input via the latch element 119.

  Next, when a failure (short circuit) indicated by reference numeral 402 in FIG. 3 occurs, a current flows from the power source 112 to the current / voltage converter 117 without passing through the electromagnetic proportional valve 114, so that an excessive current is passed to the current / voltage converter 117. A current is applied, and the detection voltage V becomes a high voltage (FIGS. 3A and 3B). The detection voltage V is input to the latch element 119, and the latch element 119 is switched to an ON state, that is, to connect the digital input 137 and the ground 699. Therefore, the operation signal S1 to the overcurrent cutoff switching element 116 is turned off, and the connection between the electromagnetic proportional valve 114 and the current / voltage converter 117 is cut off. As a result, the current I applied to the current / voltage converter 117 and the detection voltage V are close to zero. Even in this failure occurrence state, the output instruction signal to the digital output 138 by the arithmetic processing unit 111 is kept on (state of reference numeral 402 on the horizontal axis in FIG. 3D). Further, the operation signal S1 to the overcurrent cutoff switching element 116 is input to the failure monitoring unit 136 via the digital input 137, and the failure monitoring unit 136 detects a failure (overcurrent) by detecting that the operation signal S1 is OFF. Detect that occurred.

  In the arithmetic processing unit 111, when a failure is detected, the return operation is automatically started regardless of whether or not the failure is repaired. That is, when a signal indicating a failure is input from the failure monitoring unit 136 to the recovery processing unit 139, the recovery processing unit 139 turns off the output signal from the digital output 138 for a short time with a predetermined delay time ΔT (FIG. 3). (D) State of reference numeral 403 on the horizontal axis). When the off signal is input from the digital output 138, the latch element 119 switches to the off state, that is, the overcurrent cutoff switching element 116 and the digital output 138 are connected again (FIG. 3 (e) of the horizontal axis 404). Status). As a result, the operation signal S1 to the overcurrent cutoff switching element 116 is turned on in the same manner as the signal D1 from the digital output 138, and the overcurrent cutoff switching element 116 is switched to the energized state.

  At this time, if the overcurrent state is not repaired, the overcurrent flows again to the current / voltage converter 117, the detection voltage V detected by the current / voltage converter 117 becomes a high voltage, and the latch element 119 It is turned on again. As a result, the overcurrent cutoff switching element 116 is switched to the cutoff state, and the connection between the current / voltage converter 117 and the electromagnetic proportional valve 114 is cut off.

  On the other hand, if the overcurrent state is repaired for some reason, the detection voltage V detected by the current / voltage converter 117 becomes a normal value, the latch element 119 maintains the off state, and the overcurrent cutoff switching element 116 is turned on. The energized state is maintained (state of reference numerals 406 to 407 on the horizontal axis in FIG. 3).

  Therefore, according to the present embodiment, when an overcurrent flows through the current / voltage converter 117 due to a line short circuit failure or a power supply short circuit failure, the latch element 119 is turned on, whereby the overcurrent cutoff switching element 116 is turned on. Since the connection between the return line 150 and the current / voltage converter 117 is interrupted, overcurrent does not flow into the control device 141, and the control device 141 is protected. Overcurrent flows in the control device from the occurrence of overcurrent until protection is performed, but this time is sufficiently shorter than the time when the current / voltage converter 117 is damaged, so the control device is protected. The

  In the present embodiment, the failure monitoring unit 136 monitors whether or not a failure has occurred, that is, the execution state of overcurrent protection. For example, when a failure occurs, a control method for other devices related to the electromagnetic proportional valve 114 is used. It is possible to change or to identify the failure location during maintenance.

  In addition, it is possible to return to the normal state from the state where overcurrent protection is implemented, so it automatically returns to normal operation even if it recovers from a failure state or when an erroneous failure determination is made. be able to.

(Second Embodiment)
Next, a second embodiment of the electromagnetic proportional valve drive control device according to the present invention will be described with reference to FIGS. FIG. 4 shows the overall configuration of the electromagnetic proportional valve drive control device. In addition, the same code | symbol is attached | subjected to the same thing as 1st Embodiment mentioned above, The description is abbreviate | omitted.

  In the first embodiment described above, the operation signal S1 to the overcurrent cutoff switching element 116 is controlled by hardware by the latch element 119, but in the second embodiment, the arithmetic processing unit 111A controls the operation signal S1. It differs in that it is controlled in software by arithmetic processing.

  That is, in the present embodiment, when the detection voltage V from the current / voltage converter 117 is input via the amplifier 118 and the A / D conversion unit 134, the failure determination unit 237 determines whether there is a failure based on the value of the detection voltage V. The output signal from the digital output 138 is controlled based on the determination result. The output signal from the digital output 138 is directly input / output as the operation signal S2 to the overcurrent cutoff switching element 116.

  The failure determination process in the failure determination unit 237 will be described with reference to FIG. FIG. 5 shows a flowchart of this failure determination process.

  In the first step S1, the variable N is set to 0.

  In the next procedure S <b> 2, the detection voltage V is read from the A / D conversion unit 134.

  In the next step S3, it is determined whether or not the read detection voltage V is higher than a predetermined voltage Vjudge. If this step S3 is denied, this process is terminated. If the step S3 is affirmed, the process proceeds to the next step S4.

  In step S4, 1 is added to the variable N.

  In the next step S5, it is determined whether or not the variable N has reached a predetermined value Njudge. When this procedure S5 is denied, it returns to procedure S2 and repeats procedure S2 and subsequent steps again. If step S4 is affirmed, the process proceeds to the next step S6.

  In step S6, it is determined that an overcurrent has actually occurred by continuously detecting a predetermined voltage (Njudge) a value for determining whether or not the detected voltage V is a predetermined voltage Vjudge, that is, an overcurrent. Is output and the process ends.

  When a failure signal is input from the failure determination unit 237, the digital output 138 outputs an operation signal S2 that notifies the overcurrent cutoff switching element 116 of the failure. The overcurrent cutoff switching element 116 receives this signal S2 and returns to the return side. The connection between the line 150 and the current / voltage converter 117 is cut off.

  Further, the operation signal S2 from the digital output 138 is also output to the failure monitoring unit 136, and is output to the return processing unit 139 as in the first embodiment.

  Therefore, even with the configuration according to the second embodiment, since the operation processing unit 111A can monitor the output state of the digital output 138 with the failure monitoring unit 136, the operation state of the overcurrent cutoff switching element 116 can be monitored. The overcurrent protection execution status can be monitored. As a result, as in the first embodiment, advanced control and improved maintainability are achieved.

  Further, since the operation state of the overcurrent cutoff switching element 116 is controlled by the operation signal S2 from the digital output 138, an off signal is output from the digital output 138 to turn off the overcurrent cutoff switching element 116. In this state, a signal for turning on the overcurrent cutoff switching element 116 can be output from the digital output 138 again by a command from the return processing unit 139 to return to the normal state. As a result, as in the first embodiment, the normal operation can be restored even when the failure state is recovered or an erroneous failure determination is made, and the reliability of the apparatus can be improved.

  In addition, by using a switching element having an overheat output cutoff function as the overcurrent cutoff switching element 116, it becomes possible to control on / off of the overcurrent cutoff switching element 116 without providing the failure determination unit 237. .

  The overheat output cutoff function is a function that cuts off the output when the inside of the switching element overheats to a certain temperature or more. The overcurrent cutoff switching element 116 is instantaneously overheated by an overcurrent applied to the control device 141 when a line short-circuit fault or a power supply short-circuit fault occurs, and the output cutoff function at the time of overheat operates. The overcurrent cutoff switching element 116 is turned off, so that no overcurrent flows in the circuit, thereby protecting the circuit. As a result, it is possible to implement protection without a circuit for detecting a failure or arithmetic processing.

  The overheat output cutoff function can be initialized by turning off the signal to the overcurrent cutoff switching element. Therefore, by outputting an off signal from the digital output 138 that is always outputting an on signal, it is possible to return from the protected state to the normal state, and the reliability of the apparatus can be improved.

  The configurations, shapes, sizes, and arrangement relationships described in the above embodiments are merely schematically shown to the extent that the present invention can be understood and implemented. Therefore, the present invention is not limited to the described embodiments, and can be variously modified without departing from the scope of the technical idea shown in the claims.

  INDUSTRIAL APPLICABILITY The present invention is used as a drive control device when a line short circuit failure occurs in an electromagnetic proportional valve provided in a construction machine or the like.

1 is a block diagram illustrating an overall configuration of an electromagnetic proportional valve drive control device according to a first embodiment of the present invention. It is a block diagram which shows the failure state which concerns on a connection of a control apparatus, a power supply, and an electromagnetic proportional valve. It is a wave form diagram which shows the whole change of the operation waveform of each part in 1st Embodiment. It is a block diagram which shows the whole structure of the electromagnetic proportional valve drive control apparatus which concerns on the 2nd Embodiment of this invention. It is a flowchart which shows the flow of the failure determination process in 2nd Embodiment. It is a block diagram of the conventional inductive load drive device shown by patent document 1. FIG. It is a block diagram of the conventional solenoid valve drive device shown by patent documents 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 111 Arithmetic processing part 112 Power supply 113 Excitation current feeding switching element 114 Electromagnetic proportional valve 115 Load current recirculation element 116 Overcurrent cutoff switching element 117 Current / voltage converter 118 Amplifier 119 Latch element 131 Command value generation part 132 Duty ratio calculation part 133 PWM signal generation unit 134 A / D conversion unit 135 Detection voltage storage unit 136 Fault monitoring unit 137 Digital input 138 Digital output 139 Return processing unit

Claims (10)

An excitation current feeding switching element that is provided between a power source and an electromagnetic proportional valve and energizes the coil of the electromagnetic proportional valve in response to a signal, and a current / voltage that converts the excitation current flowing through the electromagnetic proportional valve into a voltage. In an electromagnetic proportional valve drive control device comprising conversion means,
When an overcurrent is applied to the electromagnetic proportional valve drive device due to a short circuit of a power supply line or the like outside the electromagnetic proportional valve drive control device, an excess current is cut off from the electromagnetic proportional valve to the current / voltage conversion means. An electromagnetic proportional valve drive control device comprising a current interrupting switching element.   The overcurrent cutoff switching element is turned on in a normal state without being related to the on / off state of the excitation current feeding switching element, and is turned off only when an overcurrent is cut off. The electromagnetic proportional valve drive control device according to claim 1.   3. An electromagnetic proportional valve according to claim 2, further comprising: a latch element that controls on / off of the overcurrent cutoff switching element using a detection voltage converted by the current / voltage conversion means when an overcurrent is generated as a trigger. Drive control device.   Provided is a monitoring means for inputting an on / off control signal to the overcurrent cutoff switching element in accordance with the operation of the latch element and monitoring an execution state of protection against the overcurrent based on the on / off control signal. The electromagnetic proportional valve drive control device according to claim 3.   When the signal from the monitoring means is input, and the signal is in an execution state of protection against the overcurrent, the latch element is in an initial state in order to return the overcurrent cutoff switching element from the cutoff state to the energized state. 5. The electromagnetic proportional valve drive control device according to claim 4, further comprising return processing means for generating an instruction signal to be returned to.   The detection voltage converted by the current / voltage conversion means is input, the presence / absence of the overcurrent is determined based on the detection voltage, and the overcurrent cutoff switching element is turned on / off according to the determination result. 3. The electromagnetic proportional valve drive control device according to claim 2, further comprising a processing means.   7. The electromagnetic device according to claim 6, further comprising monitoring means for monitoring an execution state of protection against the overcurrent based on an on / off control signal output from the arithmetic processing means to the overcurrent cutoff switching element. Proportional valve drive control device.   When the signal from the monitoring means is input and the signal is in an execution state of protection against the overcurrent, the overcurrent cutoff switching is performed to return the overcurrent cutoff switching element from the cutoff state to the energized state. 8. The electromagnetic proportional valve drive control device according to claim 7, further comprising return processing means for directly outputting a return signal to the element.   The electromagnetic proportional valve drive control device according to claim 1, wherein a switching element having an overheat output cutoff function is used as the overcurrent cutoff switching element.   The electromagnetic proportional valve drive control device according to claim 1, wherein the electromagnetic proportional valve is an electromagnetic proportional valve provided in a hydraulic circuit of a construction machine.

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