JP3021911B2 - Drive unit for linear solenoid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device for a linear solenoid which feedback-controls a current flowing through a linear solenoid, and more particularly to a drive for a linear solenoid which can detect a failure such as a disconnection or a short circuit in a drive device including the linear solenoid. Related to the device.

[0002]

2. Description of the Related Art Conventionally, in a driving apparatus for a linear solenoid, as disclosed in, for example, Japanese Patent Application Laid-Open No. 60-215174, a resistor having a current actually flowing through the linear solenoid is provided in series with the linear solenoid. A so-called feedback control system is adopted which detects a voltage between both ends of the linear solenoid and controls a current supplied to the linear solenoid so that the detected voltage becomes a desired voltage.

In order to detect a disconnection or a short circuit occurring in a current path of a linear solenoid, a device of this type generally includes a current detection resistor Rs connected in series with a linear solenoid L as shown in FIG. Is amplified by an amplifying circuit 82 comprising an operational amplifier OP01 and resistors R01 to R04, and further integrated by an integrating circuit 84 comprising a resistor R05 and a capacitor C01 to flow through the linear solenoid L. A failure detection circuit is provided which detects the average current as a voltage signal and compares the detected voltage with a reference voltage by a comparator comprising an operational amplifier OP02 to determine a failure.

[0004]

However, in the above-described conventional failure detection circuit, when the current flowing through the linear solenoid L is large, a failure in the control system can be detected, but the current flowing through the linear solenoid L is small. in case of,
There was a problem that a failure of the control system could not be properly detected.

That is, in this type of device, when the resistance value of the current detection resistor Rs is increased, the power consumption by the current detection resistor Rs is increased. Therefore, it is necessary to reduce the resistance value of the current detection resistor Rs to a value as small as possible. There is. For this reason, for example, when the resistance value of the current detection resistor Rs is set to 0.3Ω and the linear solenoid L is driven with a conduction current between the average current 1A and 0.2A, the current detection resistor Rs Is varied between 0.3 V and 0.06 V. In order to be able to always perform the failure determination, the reference voltage is set to the detection voltage 0.
It must be set to a value smaller than 06V. However, in order to determine a failure by setting the reference voltage to a value smaller than 0.06 V, it is necessary to make the failure detection circuit highly accurate, and it has been difficult to realize this as a practical problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to make it possible to always accurately detect a failure such as a disconnection or a short circuit of a linear solenoid driving device by a simple detection circuit which does not require accuracy. And

[0007]

In order to achieve the above object, the present invention provides a current detecting means for detecting a current flowing through a linear solenoid, and a difference between a result of detection by the current detecting means and a target current. An error signal generating means for integrating the error signal to generate an error signal; an energization control means for energizing the linear solenoid based on the error signal generated by the error signal generating means; A drive unit for a linear solenoid, comprising: a failure detection unit configured to compare a magnitude of the error signal with a preset reference signal and detect a failure of the drive device in accordance with the comparison result. I have.

[0008]

In the linear solenoid driving apparatus according to the present invention, the current detecting means detects the current flowing through the linear solenoid, and the error signal generating means determines the detection result. An error signal is generated by integrating the difference with the target current, and the energization control means controls energization of the linear solenoid based on the generated error signal. That is, the drive device of the present invention performs feedback control of the current supplied to the linear solenoid.

Next, in the driving device according to the present invention, the failure detecting means converts the error signal generated by the error signal generating means into
By comparing the magnitude with a preset reference signal, a failure of the driving device is detected. That is, when the drive device is operating normally, the current supplied to the linear solenoid is controlled according to the target current, so that the error signal does not greatly deviate from the reference value representing the error 0. ,
When a failure such as disconnection or short-circuit occurs, the error signal is integrated by the error signal generating means, and the error signal diverges to the maximum or minimum voltage that can be output by the error signal generating means. Therefore, in the present invention, the error signal generated by the error signal generation means is used instead of the signal from the current detection means representing the current actually flowing to the linear solenoid as in the conventional device, and the divergence state of the error signal is used. Failures are detected.

Therefore, according to the present invention, one or both of the maximum voltage and the minimum voltage that can be output by the error signal generating means and the error 0 are used as the reference voltage used for failure detection.
By setting a voltage between the reference value and the reference value, it is possible to always accurately detect the failure of the device, and to perform the failure detection without configuring the failure detection circuit with high accuracy unlike the conventional device. Will be able to

[0011]

Embodiments of the present invention will be described below with reference to the drawings. First, FIG. 1 is an electric circuit diagram showing a configuration of a linear solenoid driving device according to an embodiment to which the present invention is applied.

As shown in FIG. 1, the driving device of this embodiment is
A hydraulic control valve that controls a vehicle control line hydraulic pressure (for example, a brake hydraulic pressure for anti-skid control, a transmission hydraulic pressure for automatic transmission control, etc.) that is pressure-fed from a hydraulic pump driven by an internal combustion engine to a predetermined operating hydraulic pressure. This is for controlling the energizing current of the driving linear solenoid L, and operates upon receiving a control signal output from the microcomputer 4 and representing the target current of the linear solenoid L.

As shown in FIG. 2A, the microcomputer 4 outputs a High level at predetermined intervals as a control signal.
Since the duty signal whose ratio to the Low level is controlled is output, the drive device of the present embodiment applies the control signal (Duty signal) from the microcomputer 4 by integration processing or the like. A duty-voltage conversion circuit 10 for converting an analog voltage signal shown in FIG. 2B is provided.

Further, in the driving device of the present embodiment, in order to detect a current (solenoid current) flowing through the linear solenoid L, a current detecting resistor Rs as current detecting means connected in series to the linear solenoid L; By integrating the difference between the voltage across the current detection resistor Rs (shown in FIG. 2F) and the output voltage from the duty-voltage conversion circuit 10, an error signal shown in FIG. 2C is generated. And an error signal generation circuit 20 as error signal generation means.

The error signal generating circuit 20 includes an amplifying circuit 22 including an operational amplifier OP1 for amplifying a voltage detected by the current detecting resistor Rs and resistors R1 to R4;
2 and the duty-voltage conversion circuit 1
Operational amplifier OP for differentially integrating and amplifying a command voltage from 0
2, a differential integrating amplifier circuit 24 including a resistor R5 and a capacitor C1.

Next, the error signal generated by the error signal generation circuit 20 is input to a linear solenoid drive duty signal generation circuit 30. The linear solenoid drive duty signal generation circuit 30 is for generating a duty drive signal for the linear solenoid L by comparing the error signal with a triangular wave shown in FIG. Then, the difference between the error signal and the triangular wave is compared by the differential amplifier circuit 32 composed of a comparator, and the polarity of the signal is inverted by the inversion circuit 34 to drive the PNP transistor, as shown in FIG. Drive signal to be generated.

The drive signal generated by the linear solenoid drive duty signal generation circuit 30 is connected to a resistor R
6, R7, PNP transistor TR1 and diode D
1 is inputted to the driving circuit 40 comprising
By the operation described above, the current supplied to the linear solenoid L is controlled according to the drive signal. In the present embodiment, the linear solenoid drive duty signal generation circuit 30 and the drive circuit 40 function as the above-described power supply control means.

As described above, in the linear solenoid driving device of the present embodiment, the current flowing through the linear solenoid L is detected by the current detection resistor Rs, and the current is controlled so as to correspond to the command from the microcomputer 4. That is, a so-called feedback control system is configured.
For this reason, if there is no failure such as disconnection or short-circuit in the current path of the linear solenoid L, the signals of the above components are in a state before the time point t1 shown in FIG. 2 and the error signal becomes the reference level Vs indicating the error 0. Controlled.

However, if a failure such as disconnection or short-circuit occurs in the linear solenoid L or the driving device at the time t1 shown in FIG. 2, the solenoid current, and hence the voltage detected by the current detection resistor Rs, becomes As shown by the solid line or the dotted line in FIG. Therefore, the error signal generation circuit 20 continues to integrate the difference between the detected voltage and the output voltage from the duty-voltage conversion circuit 10, and the error signal is grounded to the differential integration amplifier circuit 24 as shown in FIG. Diverge to the level or power supply level.

For example, when the linear solenoid L itself breaks, the detection voltage representing the solenoid current is fixed at 0 V as shown by the solid line in FIG. 2 (f), and the error signal is shown in FIG. 2 (c).
, The power supply voltage Vd of the differential integration amplifier 24 as shown by the solid line.
Diverging until. Conversely, when the linear solenoid L is short-circuited, the detection voltage representing the solenoid current is fixed at a value near the power supply voltage Vd as shown by the dotted line in FIG. 2 (f), and the error signal is shown as the dotted line in FIG. 2 (c). It diverges to the ground level of the differential integration amplifier circuit 24.

At this time, since the error signal greatly deviates from the normal operation range centered on the reference level Vs, as shown in FIG. 2C, the reference voltage V is out of the normal operation range.
A and VB are set (for example, when the power supply voltage Vd is 9 V, the reference voltage VA is set to about 6 V and the reference voltage VB is set to about 0.7 V), and the error signal is equal to or higher than the reference voltage VA, or If it is determined whether the voltage is equal to or lower than the reference voltage VB,
Failure of the drive device including the linear solenoid L can be detected easily and reliably.

Therefore, in this embodiment, as shown in FIG. 1, the error signal output from the error signal generation circuit 20 is compared with the reference voltage VA, and only when the error signal becomes higher than the reference voltage, the low level is output. A comparator 52 for outputting a signal,
A failure detection circuit 50 including a comparator 54 that compares the error signal output from the error signal generation circuit 20 with the reference voltage VB, and outputs a low-level signal only when the error signal is equal to or higher than the reference voltage. Is input to the microcomputer 4 via an input circuit 60 including a pull-up resistor R8 and an input resistor R9, so that the microcomputer 4 determines whether the input signal is at a low level. Depending on whether it is at the high level, it is possible to detect a failure of the device (it becomes a low level at the time of failure).

As described above, in the linear solenoid driving device of the present embodiment, the detection voltage indicating the actual energizing current of the linear solenoid L and the duty-voltage conversion circuit 10 indicating the target current of the linear solenoid L Since the device failure is detected by an error signal in the feedback loop obtained by integrating the difference with the output voltage, the device failure can be easily and reliably detected. The error signal is obtained by integrating the difference between the voltages, and the operating range of the error signal does not change with a change in the target current, so that a fault can be always detected.

In the above embodiment, in the failure detection circuit 50, the reference voltage VA on the power supply voltage side and the reference voltage VB on the ground side are set, and these reference voltages are compared with the error signal to determine whether the disconnection or disconnection has occurred. Although both short-circuits are detected, if the current detection resistor Rs only detects a disconnection in the current path on the power supply side, the failure detection circuit 50 is connected to the comparator 54 for comparing the error signal with the reference voltage VB. If only a short circuit is to be detected, on the contrary, the failure detection circuit 50 is connected to the error signal and the reference voltage V.
A may be configured only by the comparator 52 that compares A with A.

In the above embodiment, the case where the current detection resistor Rs is connected to the ground side of the linear solenoid L has been described. However, the same effect as this embodiment can be obtained by connecting the current detection resistor Rs to the power supply side of the linear solenoid L. Can be

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram illustrating a configuration of an entire linear solenoid driving device according to an embodiment.

FIG. 2 is a time chart showing signal waveforms of various parts in the linear solenoid driving device of the embodiment.

FIG. 3 is an electric circuit diagram showing a failure detection circuit in a conventional linear solenoid driving device.

[Explanation of symbols]

4 ... Microcomputer 10 ... Duty-voltage conversion circuit 20 ... Error signal generation circuit 30 ... Linear solenoid drive duty signal generation circuit 40 ... Drive circuit 50 ... Fault detection circuit Rs ... Current detection resistance

Claims (1)

(57) [Claims] A current detection means for detecting a current flowing through the linear solenoid; an error signal generation means for integrating a difference between a result of detection by the current detection means and a target current to generate an error signal; Energization control means for energizing the linear solenoid based on the error signal generated by the means; and comparing the magnitude of the error signal generated by the error signal generation means with a preset reference signal. And a failure detecting means for detecting a failure of the driving device in response thereto. A driving device for a linear solenoid, comprising: