JP2000114039A - Device for detecting failure in linear solenoid - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the state in the wiring system of linear solenoid or at the time of ground short circuit for a short period, and to prevent the deterioration and breakage of a transistor or a resistance element, etc., as a driving means. SOLUTION: An output voltage VB detected by a current detection circuit 10 corresponding to a driving current (i) in a linear solenoid LS is stablized by an integration circuit 700 consisting of a resistance element RA and a capacitor C, and its output voltage VC is obtained. In this case, when the linear solenoid LS comes into ground short circuit, the output voltage VB from the current detection circuit 10 shows a sharp rise, however, the state is reflected immediately to the output voltage VC of the integration circuit 700 through a diode D3 connected in parallel to the resistance element RA. Namely, since a period to detect the failure of ground short circuit where the output voltage VC from the integration circuit 700 becomes higher than a fail judgment voltage is extremely short, the deterioration and breakage of a transistor Tr or a resistance element as a driving means for the linear solenoid can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear solenoid failure detecting device for detecting a drive current for controlling a linear solenoid to determine a failure.

[0002]

2. Description of the Related Art Conventionally, in order to cope with an excessive load impedance due to a ground short of a linear solenoid or the like, and to protect a transistor or a resistance element as a driving stage thereof, a linear configuration mainly having a hardware configuration as shown in FIG. Solenoid failure detection devices are known. In FIG.
The voltage (i.times.R1) between the terminals of the resistance element R1 corresponding to the drive current i of the coil CL of the linear solenoid LS is detected by the current detection circuit 10 via the resistance elements R2 and R3, and the output signal is fed back to the feedback circuit 90. Has been entered. In addition, the PWM (Puls
e Width Modulation (Pulse width modulation) PW from port
A command value based on the M signal is input to the feedback circuit 90. This feedback circuit 90 outputs an output signal from the current detection circuit 10 and the microcomputer 100
An output signal based on the difference from the command value from the
P-channel MOSFET (Metal Oxide Se
micon Field Effect Transistor (MOS field effect transistor; hereinafter simply referred to as "transistor Tr"). As a result, the transistor Tr is controlled to be ON (ON) / OFF (OFF),
The drive current i is supplied from the power supply + B to the coil CL of the linear solenoid LS.

On the other hand, the coil CL of the linear solenoid LS
Between the terminals of the resistance element R4 corresponding to the drive current i (i
× R4) is detected by the failure detection current detection circuit 40 via the resistance elements R5 and R6, and the output signal is input to the comparison determination circuit 50. The output signal from the comparison / determination circuit 50 is input to the AND circuit 30 via the latch circuit 60. Thus, the drive current i flowing through the coil CL of the linear solenoid LS is constantly monitored by the failure detection current detection circuit 40.

Here, when the wiring of the linear solenoid LS bites into the ground of the wiring or the short circuit of the coil CL occurs, the drive current i increases abnormally, and the output signal from the fault detecting current detecting circuit 40 increases accordingly. You. When the output signal from the failure detection current detection circuit 40 exceeds a predetermined failure determination value of the comparison determination circuit 50, it is determined that an overcurrent abnormality has occurred and the output signal from the latch circuit 60 to the AND circuit 30 is set to "0". And the transistor Tr, which is the driving stage, is turned off. Note that an ICR (Input Capture) port of the microcomputer 100 has an edge detection function for an input signal and an output A
Each port has a latch release function for the latch circuit 60.

Further, in order to cope with ground short-circuit of the linear solenoid and to protect a transistor, a resistance element and the like as a driving stage thereof, a linear solenoid failure detection mainly using a software configuration using a microcomputer as shown in FIG. Devices are known. Here, a description will be given with reference to a time chart of FIG. 8 showing a specific transition state of a voltage waveform and the like when the linear solenoid LS changes from a normal state to a ground short circuit in the configuration of FIG.

In FIG. 7, a drive voltage Vα (see FIG. 8) corresponding to a drive current i supplied from a power source + B is applied to a coil CL of the linear solenoid LS in a normal state. Then, the voltage between the terminals of the resistance element R1 (i × R1)
Is detected by the current detection circuit 10 through the resistance elements R2 and R3, and the output voltage Vβ (see FIG. 8) is
Has been entered. The output voltage V from the integrating circuit 70
γ (see FIG. 8) is the A / D of microcomputer 100
(Analog-digital conversion) port. Then, a command value based on a PWM signal from a PWM port of the microcomputer 100 is input to the drive circuit 20.

Here, the coil C of the linear solenoid LS
The output voltage Vβ from the current detection circuit 10 corresponding to the driving current i of L is superimposed on the induction noise from the output system, to prevent erroneous diagnosis by the microcomputer 100, and When the command value to the drive circuit 20 is feedback corrected and controlled by the detected current, an integrating circuit 70 composed of a well-known CR circuit including a capacitor and a resistance element is used in order to prevent occurrence of abnormality in the correction control.
Stable voltage V after being smoothed (smoothed) at
γ (see FIG. 8) and A of the microcomputer 100
/ D port. Then, based on the internal calculation by the microcomputer 100, the PWM output from the PWM port is output to the drive circuit 20, and the output signal turns on / off the transistor Tr, so that the desired drive current i is supplied to the coil CL of the linear solenoid LS. Will be supplied.

Voltage V smoothed by integrating circuit 70
When the coil CL of the linear solenoid LS changes from a normal state to a ground short circuit, γ is gradually increased as shown in FIG. The time from when the voltage Vγ exceeds the predetermined fail determination voltage until the time when the voltage Vγ exceeds the preset fail determination voltage is the ground short failure detection time, and the microcomputer 100 executes the fail processing from that time. That is, the PW from the microcomputer 100
M output is stopped and output signal from drive circuit 20 is OFF
As a result, the transistor Tr is turned off, and the supply of the drive current i flowing through the coil CL of the linear solenoid LS is stopped.

[0009]

When the linear solenoid is short-circuited to the ground, it is necessary to protect the drive stage such as a transistor and a resistance element by detecting the linear solenoid failure mainly by the hardware configuration shown in FIG. A large-scale circuit configuration having a function of detecting an overcurrent in a short time and shutting off the output, such as a device, is required, which hinders downsizing and cost reduction of the linear solenoid failure detection device. Further, in the linear solenoid failure detection device mainly including the software configuration shown in FIG.
As shown in the figure, when the ground of the coil CL of the linear solenoid LS is ground short, an excessive current is a long time obtained by adding the ground short fault detection time and the fail processing time,
It flows to the transistor Tr, the resistance element R1 and the like. As described above, when the ground of the coil CL of the linear solenoid LS is short-circuited, the longer the time from the failure detection to the fail processing, the more the deterioration and destruction of the drive stage element of the linear solenoid LS increase. In order to cope with this, it is necessary to use a large power element having a ground short-circuit tolerance for a transistor or a resistance element of a driving stage, which has hindered a cost reduction of a linear solenoid failure detection device.

Accordingly, the present invention has been made to solve such a problem, and has a simple circuit configuration without having to increase the ground short-circuit tolerance of a transistor or a resistor as a drive stage of a linear solenoid. It is an object of the present invention to provide a linear solenoid failure detection device capable of preventing deterioration and destruction of a drive stage element when a ground of a coil of a linear solenoid is short-circuited.

[0011]

According to the linear solenoid failure detecting device of the present invention, the output value detected by the current detecting circuit corresponding to the driving current of the linear solenoid is formed by the integrating circuit comprising the resistance element and the capacitor. And the output value is obtained. Here, when the linear solenoid is short-circuited to ground, the output value from the current detection circuit rises steeply, and is immediately reflected on the output value of the integration circuit by an electric element connected in parallel with the resistance element. As a result, when the linear solenoid is short-circuited to the ground, the failure detection time until a failure is determined based on the output value from the integration circuit can be extremely short, so that the drive stage element of the linear solenoid is prevented from being deteriorated or destroyed. Is done.

The linear solenoid failure detecting device according to the second aspect has a simple circuit configuration in which a diode as an electric element is connected in parallel with the capacitor in the forward direction to the resistance element of the integration circuit. Here, when the linear solenoid is short-circuited to the ground, the output value from the current detection circuit rises steeply, but is immediately reflected in the output value of the integration circuit via the diode connected in parallel with the resistance element, and a failure determination is made. Since the time required to detect a failure before the failure can be extremely short, deterioration and destruction of the drive stage element of the linear solenoid can be prevented.

According to a third aspect of the present invention, there is provided a linear solenoid failure detecting device, wherein a P as an electric element is connected in parallel with the resistance element of the integration circuit.
It has a simple circuit configuration in which an NP transistor and an NPN transistor are additionally connected. Here, when the linear solenoid is short-circuited to ground, the output value from the current detection circuit rises steeply, but is immediately reflected in the output value of the integration circuit via the PNP transistor and NPN transistor connected in parallel to the resistance element. Since the failure detection time until the failure determination is made can be extremely short, deterioration and destruction of the drive stage element of the linear solenoid can be prevented.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples.

Embodiment 1 FIG. 1 is a schematic diagram showing a linear solenoid failure detecting device according to a first embodiment of the present invention. Note that components having the same configuration or corresponding portions as those of the above-described conventional device are denoted by the same reference numerals and symbols.

In FIG. 1, a microcomputer 10
A command value based on a PWM signal from a PWM port of 0 and a detection value as an output voltage of a current detection circuit 10 described later are input to the drive circuit 20. The output signal of the drive circuit 20 is input to the gate G of the transistor Tr (P-channel MOSFET). The source S of the transistor Tr is connected to the power supply + B, and the drain D is connected to the coil C of the linear solenoid LS via the resistor R1.
Connected to one end of L. The other end of the coil CL of the linear solenoid LS is connected to the ground.
The coil CL of the linear solenoid LS has a reactance (resistance) RL.

The high voltage side of the resistor R1 is connected to the resistor R
2 connected to the current detection circuit 10 through the resistor R1
Is connected to the current detection circuit 10 via the resistance element R3. That is, the voltage between the terminals of the resistance element R1 is input to the current detection circuit 10 via the resistance elements R2 and R3. A diode D1 is connected between the high voltage side of the resistor R1 and the ground so as to be in a forward direction with respect to the high voltage side of the resistor R1. This diode D1
Is for adding the flyback current by the coil CL of the linear solenoid LS.

The output voltage VB from the current detection circuit 10 is
It is input to the integration circuit 700. The integration circuit 700
There is a CR circuit in which a resistance element RA and a capacitor C are connected in series between the output side of the current detection circuit 10 and the ground. Further, the resistance element RA and the capacitor C are connected to the reference power supply Vcc via a diode D2 in the opposite direction to the resistance element RA. Further, a diode D3 is connected in parallel with both ends of the resistance element RA in the integrating circuit 700 of this embodiment so as to be in a forward direction with respect to the capacitor C. The voltage VC between the resistance element RA and the capacitor C, that is, the output voltage V
C is input to the A / D port of the microcomputer 100.

The microcomputer 100 includes a CPU as a well-known central processing unit, a ROM storing a control program, a RAM storing various data, and a B / U.
It is configured as a logical operation circuit including a (backup) RAM, input / output circuits, and bus lines connecting them.

With the above configuration, the command value based on the PWM signal from the microcomputer 100 is input to the drive circuit 20, and the transistor Tr is turned on / off by the output signal from the drive circuit 20, and the linear solenoid L
The drive current i is supplied from the power supply + B to the S coil CL. The voltage between the terminals of the resistance element R1 corresponding to the drive current i of the coil CL of the linear solenoid LS is constantly detected by the current detection circuit 10 via the resistance elements R2 and R3, and the output voltage from the current detection circuit 10 VB is input to the integration circuit 700. In the integration circuit 700, the output voltage VB from the current detection circuit 10 is accumulated as the quantity of electricity of the capacitor C via the resistance element RA and the diode D3, and is calculated by the microcomputer 100 as the voltage VC between the resistance element RA and the capacitor C. Will be detected. That is, the fluctuating output voltage V from the current detection circuit 10
In order to stabilize B, the integration circuit 700 performs a smoothing process by integration using the capacitor C. Then, the voltage VC between the resistance element RA and the capacitor C is read from the A / D port of the microcomputer 100.

Next, FIG. 4 will be described with reference to a flowchart of FIG. 2 showing a processing procedure of failure detection in the microcomputer 100 used in the linear solenoid failure detection device according to the first embodiment of the present invention. It will be described with reference to FIG. Here, FIG. 4 is a time chart showing a transition state of a voltage waveform and the like when the linear solenoid LS changes from a normal state to a ground short circuit in the configuration of FIG.
This failure detection routine is repeatedly executed by the microcomputer 100 at predetermined time intervals.

In FIG. 2, in step S101, A
It is determined whether the A / D converted A / D input voltage from the / D port is equal to or higher than a predetermined fail determination voltage. The determination condition of step S101 is satisfied, that is, A / D
When the input voltage becomes higher than the fail determination voltage, it is determined that a failure has occurred due to an overcurrent abnormality caused by the wiring system of the linear solenoid LS or the coil CL, and step S102 is performed.
Then, the PWM output from the PWM port is stopped. Next, the process proceeds to step S103, and the diagnosis (Diagno
After the failure of the linear solenoid LS is stored in the internal memory as a process (sis: failure diagnosis), a warning lamp (not shown) for notifying the failure is turned on, and then this routine ends.
On the other hand, the determination condition of step S101 is not satisfied, that is,
When the A / D input voltage is within the normal range, this routine ends without executing the fail process.

As described above, in this embodiment, as shown in FIG. 4, the drive current i of the coil CL of the linear solenoid LS is
[A] is a voltage between terminals of the resistance element R1 (i × R1).
The output voltage VB [V] is detected as [V] by the current detection circuit 10, and the output voltage VB [V] is accumulated by the integration circuit 700 as the amount of electricity of the capacitor C via the resistance element RA, and the voltage between the resistance element RA and the capacitor C This is detected by the microcomputer 100 as VC [V]. When the wiring system of the linear solenoid LS or the coil CL is in an overcurrent state due to ground shorting or the like from a normal state, the output voltage VB [V] from the current detecting circuit 10 is rapidly increased by the diode D3 of the integrating circuit 700.
Via the A / D port of the microcomputer 100 as an output voltage VC. That is, as shown in FIG. 4, when the coil CL of the linear solenoid LS changes from a normal state to a ground short circuit, a ground short circuit failure occurs until the output voltage VC [V] from the integrating circuit 700 becomes equal to or higher than the fail determination voltage. The detection time can be extremely short.

As described above, the linear solenoid failure detecting device according to the present embodiment includes the linear solenoid LS for obtaining a predetermined displacement amount according to the magnitude of the drive current i, and the drive circuit 20 for controlling the drive current i. Current detection circuit 10 for detecting an output value VB corresponding to drive current i, and current detection circuit 1
A resistance element RA and a capacitor C that integrate the output value VB of 0
And a predetermined value corresponding to the output value VB of the current detection circuit 10 which is connected in parallel with the resistance element RA of the integration circuit 700, follows the rising of the output value VB of the current detection circuit 10, and Is added to the output value VC from the integrating circuit. Further, the linear solenoid failure detecting device of the present embodiment has a diode D3 whose electric element is connected to the capacitor C of the integrating circuit 700 in the forward direction.

Therefore, the output value VB detected by the current detection circuit 10 corresponding to the drive current i of the linear solenoid LS is stabilized by the integration circuit 700 including the resistance element RA and the capacitor C, and the output value VC is obtained. can get. Here, when the linear solenoid LS is short-circuited to ground, the output value VB from the current detection circuit 10 rises steeply, but the diode D connected in parallel with the resistance element RA.
3 is immediately reflected in the output value VC of the integrating circuit 700. Thus, when the linear solenoid LS is short-circuited to ground, the output voltage V
Since the ground short-circuit failure detection time until C becomes equal to or higher than the fail determination voltage is extremely short, deterioration and destruction of the transistor Tr and the resistance element R1 as the drive stage of the linear solenoid LS can be prevented.

FIG. 3 is a schematic configuration diagram showing a modified example of the linear solenoid failure detecting device according to the first embodiment of the present invention. In the drawing, the same reference numerals and symbols are given to components having the same configuration or corresponding portions as those in FIG. 1, and overlapping description will be omitted.

In FIG. 3, the output voltage VC from the integrating circuit 700 is the same as that of FIG.
A / D port of the comparator COM and the inverting (-) input side of the comparator COM constituting the comparison circuit 800. On the non-inverting (+) input side of the comparator COM, the reference power supply Vcc is divided by the resistance elements RB and RC, and the voltage value ｛RC / (RB
+ RC)｝ × Vcc is input. Also, the comparator CO
A pull-up resistor RD is connected between the output terminal of M and the reference power supply Vcc, and the output voltage VD from the comparison circuit 800 is input to the ICR port of the microcomputer 100.

By setting the voltage value of the non-inverting (+) input of the comparator COM to the fail judgment voltage, the output voltage VD becomes Hi (High: high) when the wiring system of the linear solenoid LS or the coil CL has an overcurrent abnormality. → Fall to Lo (Low). By detecting the falling edge at the ICR port of the microcomputer 100, the A / D port input voltage shown in the first embodiment is read and the fail process is performed, that is, the A / D value is periodically changed. The fail process can be executed at a timing earlier than the read determination method.

<Embodiment 2> FIG. 5 is a schematic diagram showing a linear solenoid failure detecting apparatus according to a second embodiment of the present invention. In the figure, the same reference numerals and symbols are given to components having the same configuration or corresponding portions as those in FIG. 1 in the above-described embodiment, and redundant description thereof will be omitted. Also in the configuration of the present embodiment, the transition state of the voltage waveform and the like when the linear solenoid LS changes from the normal state to the ground short circuit is the same as the above-described embodiment, and will be described with reference to the time chart of FIG. I do.

In FIG. 5, like the integration circuit 700, the integration circuit 700 'has a CR circuit in which a resistance element RA and a capacitor C are connected in series between the output side of the current detection circuit 10 and the ground. ing. Also, instead of the diodes D2 and D3 in the integrating circuit 700 of the above-described embodiment, in the integrating circuit 700 ', the collector side of the PNP transistor Tr1 whose emitter is connected to the reference power supply Vcc via the resistor RE is connected to the resistor RA and the capacitor C. Connected between The collector of the NPN transistor Tr2 is connected to the base of the PNP transistor Tr1 via the resistance element RF. The emitter side of the NPN transistor Tr2 is connected to the ground, and the base side is connected to the output side of the current detection circuit 10.

The voltage between the terminals of the resistor R1 corresponding to the drive current i of the coil CL of the linear solenoid LS is constantly detected by the current detection circuit 10 via the resistors R2 and R3. The output voltage VB from the current detection circuit 10 is input to the integration circuit 700 '. In the integration circuit 700 ', the output voltage VB from the current detection circuit 10 is applied to the resistance element RA.
Is stored as an electric quantity of the capacitor C through the microcomputer 100, and is detected by the microcomputer 100 as a voltage value VC between the resistance element RA and the capacitor C. That is, in the integration circuit 700 ', a smoothing process is performed by integration using the capacitor C in order to stabilize the fluctuating output voltage VB detected by the current detection circuit 10. Then, the voltage value VC between the resistance element RA and the capacitor C
Is read from the A / D port of the microcomputer 100.

That is, as shown in FIG. 4, the drive current i [A] of the coil CL of the linear solenoid LS is detected by the current detection circuit 10 as a voltage (i × R1) [V] between the terminals of the resistance element R1. The output voltage VB [V] is accumulated as an electric quantity of the capacitor C via the resistor RA by the integrating circuit 700 ', and the microcomputer 100 generates a voltage VC [V] between the resistor RA and the capacitor C by the microcomputer 100. Will be detected.

Here, the coil C of the linear solenoid LS
When L changes from normal to ground short,
An integrating circuit 700 'which is OFF in a normal current state due to an excessive rise of the output voltage VB [V] from the current detecting circuit 10.
NPN transistor Tr2 is turned ON. This allows
The PNP transistor Tr1 also changes from OFF to ON, the reference power source Vcc is added, and the output voltage VC is input from the A / D port of the microcomputer 100. That is, also in this embodiment, as shown in FIG. 4, when the coil CL of the linear solenoid LS changes from a normal state to a ground short-circuit, the output voltage V
The ground short failure detection time until C [V] becomes equal to or higher than the fail determination voltage can be extremely short.

As described above, in the linear solenoid failure detecting device according to the present embodiment, the electric elements are composed of the PNP transistor Tr1 and the NPN transistor Tr2, and the collector of the PNP transistor Tr1 connected to the reference power source Vcc is connected to the integrating circuit 700. ′ Is connected between the resistance element RA and the capacitor C, and the base side of the PNP transistor Tr1 is connected to the collector of the NPN transistor Tr2.
The emitter of the transistor Tr2 is connected to the ground, and the base of the NPN transistor Tr2 is connected to the output of the current detection circuit 10.

Therefore, when the linear solenoid LS is short-circuited to the ground, the output value V
B rises steeply, but is immediately reflected on the output value VC of the integrating circuit 700 via the PNP transistor Tr1 and the NPN transistor Tr2 connected in parallel with the resistance element RA. Accordingly, when the linear solenoid LS is ground short-circuited, the ground short-circuit failure detection time until the output voltage VC from the integration circuit 700 becomes equal to or higher than the fail determination voltage can be extremely short, and the drive stage of the linear solenoid LS Transistor Tr as
And the resistance element R1 can be prevented from being deteriorated or destroyed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a linear solenoid failure detection device according to a first example of an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a processing procedure of failure detection in a microcomputer used in the linear solenoid failure detection device according to the first example of the embodiment of the present invention.

FIG. 3 is a schematic configuration diagram showing a modification of the linear solenoid failure detection device according to the first example of the embodiment of the present invention.

FIG. 4 is a time chart showing a transition state of a voltage waveform and the like when the linear solenoid changes from a normal state to a ground short circuit in the configuration of FIG. 1 or FIG. 3;

FIG. 5 is a schematic configuration diagram showing a linear solenoid failure detection device according to a second example of the embodiment of the present invention.

FIG. 6 is a block diagram showing a conventional linear solenoid failure detection device mainly composed of hardware.

FIG. 7 is a block diagram showing a conventional linear solenoid failure detection device mainly composed of software.

8 is a time chart showing a transition state of a voltage waveform and the like when the linear solenoid changes from a normal state to a ground short circuit in the configuration of FIG. 7;

[Explanation of symbols]

 LS Linear solenoid Tr Transistor (MOSFET) RA Resistance element C Capacitor D3 Diode 10 Current detection circuit 20 Drive circuit 100 Microcomputer 700 Integration circuit

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[Procedure amendment]

[Submission date] October 5, 1998 (1998.10.
5)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction contents]

[0009]

When the linear solenoid is short-circuited to the ground, it is necessary to protect the drive stage such as a transistor and a resistance element by detecting the linear solenoid failure mainly by the hardware configuration shown in FIG. A large-scale circuit configuration having a function of detecting an overcurrent in a short time and shutting off the output, such as a device, is required, which hinders downsizing and cost reduction of the linear solenoid failure detection device. Further, in the linear solenoid failure detection device mainly including the software configuration shown in FIG.
As shown in the figure, when the ground of the coil CL of the linear solenoid LS is ground short, an excessive current is a long time obtained by adding the ground short fault detection time and the fail processing time,
It flows to the transistor Tr, the resistance element R1 and the like. Thus, when ground short coil CL of the linear solenoid LS, the fault detection the longer the time to failure process, the deterioration of the driving stage elements of the linear solenoid LS, concerns fracture increases. In order to cope with this, it is necessary to use a large power element having a ground short-circuit tolerance for a transistor or a resistance element of a driving stage, which has hindered a cost reduction of a linear solenoid failure detection device.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

In FIG . 1, a microcomputer 10
Command value is driven by PWM signal from PWM port 0
It is input to the circuit 20. The output signal of the drive circuit 20 is input to the gate G of the transistor Tr (P-channel MOSFET). The source S of the transistor Tr is connected to the power supply + B, and the drain D is connected to the coil C of the linear solenoid LS via the resistor R1.
Connected to one end of L. The other end of the coil CL of the linear solenoid LS is connected to the ground.
The coil CL of the linear solenoid LS has a reactance (resistance) RL.

Claims (3)

[Claims] 1. A linear solenoid for obtaining a predetermined amount of displacement according to the magnitude of a drive current, a drive circuit for controlling the drive current, and a current detection circuit for detecting an output value corresponding to the drive current An integration circuit including a resistance element and a capacitor for integrating the output value of the current detection circuit, and an integration circuit connected in parallel to the resistance element in the integration circuit;
At least one of following a rise of the output value from the current detection circuit and adding a predetermined value corresponding to the output value from the current detection circuit to an output value from the integration circuit.
A linear solenoid failure detecting device, comprising: two electric elements. 2. The linear solenoid failure detecting device according to claim 1, wherein the electric element is formed of a diode connected in a forward direction to the capacitor of the integration circuit. 3. The electric element includes a PNP transistor and an NPN transistor, and a collector side of the PNP transistor connected to a power supply by an emitter is connected between the resistance element and the capacitor of the integration circuit. The NPN transistor is collector-connected to the base side of the PNP transistor,
The linear solenoid failure detection device according to claim 1, wherein an emitter side of the NPN transistor is connected to a ground side, and a base side of the NPN transistor is connected to an output side of the current detection circuit.