JPH0684636A - Solenoid controller - Google Patents

Abstract

PURPOSE:To enhance reliability in the decision of failure of solenoid by comparing a control signal and a detection signal at the timing of sampling signal having period sufficiently shorter than the pulse period of driving signal and making a decision that a solenoid has falied if a state where comparison results do not match each other sustains longer than a predetermined interval. CONSTITUTION:A CPU 11 outputs an ON/OFF control signal C depending on the operating conditions and subjects a solenoid 6 to duty driving according to a driving signal A through a drive circuit 13. On the other hand, the driving signal A is fed back through a detecting circuit 14 and the voltage at one end of the solenoid 6 is inputted as a detection signal D. A timer in the CPU 11 generates a sampling signal and ON/OFF states of the control signal C and the detection signal D are compared for every period of the sampling signal. A decision is then made whether the mismatch interval sustains longer than a set interval. The set interval corresponds to the minimum pulse width of the control signal C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solenoid control device for driving a transmission of an automatic transmission engine with a duty solenoid and for determining a failure of a solenoid, and more particularly, it can reliably determine a failure of a solenoid. The present invention relates to a solenoid control device.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram showing a general solenoid control device together with an engine. In the figure, 1 is an engine with an automatic transmission, 2 is a transmission including a transmission provided on the output side of the engine 1, 3 is a throttle sensor for detecting a throttle opening B of the engine 1, and 4 is a throttle sensor.
Is a vehicle speed sensor for detecting a vehicle speed V according to the number of revolutions of the engine 1, 5 is an oil temperature sensor for detecting an oil temperature K of a hydraulic system for driving the transmission 2, and 6 is a duty control for driving the hydraulic system of the transmission 2. A solenoid 10 is a control unit that outputs a drive signal A to the solenoid 6 based on operating conditions such as the throttle opening B, the vehicle speed V, and the oil temperature K.

FIG. 4 is a block diagram concretely showing the control unit 10, which is composed of the following 11 to 15. Reference numeral 11 denotes a CPU including an input interface and an output interface, which inputs various operating states, that is, a throttle opening B, a vehicle speed V and an oil temperature K, and a control signal C corresponding to the drive signal A.
And the detection signal D indicating the driving state of the solenoid 6 is input, and the failure flag F is output when the failure of the solenoid 6 is determined.

Reference numeral 12 is a power supply for driving the control unit 10. 13 is a drive circuit composed of PNP transistors,
The power supply 12 is connected to the emitter, the control signal C is applied to the base, and the drive signal A is output from the collector. 14
Is a detection circuit for outputting the fed back drive signal A as the detection signal D, and 15 is an output terminal for applying the drive signal A to one end of the solenoid 6.

Next, the operation of the conventional solenoid control device will be described with reference to FIGS. 3 and 4. The CPU 11 in the control unit 10 generates a control signal C based on the operating states B, V and K from various sensors, and the drive circuit 12 drives the solenoid 6 on and off based on the control signal C. Generate A.

In response to the drive signal A, the solenoid 6 controls the switching of the hydraulic path in the transmission 2, operates the clutch by the hydraulic pressure corresponding to the required torque, and automatically controls the shift. However, if a failure occurs in the solenoid 6, for example, the state that should be "4th speed" control is changed to "1st speed" control, and the gear shifts to a gear other than the intended gear, which is extremely dangerous. .

Therefore, the control unit 10 has a solenoid 6
4, the control signal C is fed back from one end of the solenoid 6 as a detection signal D as shown in FIG. That is, the CPU 11 compares the control signal C for the drive circuit 13 with the detection signal D from the detection circuit 14, and determines whether the drive state of the solenoid is good or not depending on whether they match. If it is determined that the solenoid 6 is out of order, the failure flag F is output and the transmission 2 is arbitrarily switched to the safe side control.

At this time, the control signal C and the detection signal D are compared at the timing of the sampling signal having a cycle corresponding to the timer capability of the CPU 11. However, when noise is superimposed on the control signal C or the detection signal D in synchronization with the sampling timing, the CPU 11 detects the discrepancy between the two signals and determines the malfunction of the solenoid 6.

Particularly, in the hydraulic control of the transmission 2 in recent years, the control by the duty solenoid is performed, and the pulse period of the control signal C is several tens of milliseconds, so the pulse width is short to about several milliseconds. Can be. Therefore, the period of the sampling signal is set to about 1 msec, which is shorter than the pulse width of the control signal C, but the number of sampling increases, so that it is more susceptible to noise.

[0010]

As described above, since the conventional solenoid control device immediately determines the failure of the solenoid 6 when it detects the mismatch between the control signal C and the detection signal D, it may cause a noise. There is a problem that the failure state may be erroneously determined due to the influence.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain a solenoid control device capable of reliably determining the failure of a solenoid.

[0012]

In the solenoid control device according to the present invention, the control signal and the detection signal are compared at the timing of the sampling signal having a period sufficiently shorter than the pulse period of the drive signal, and the comparison results are inconsistent. When the state continues for a predetermined period or more, the failure of the solenoid is determined.

[0013]

According to the present invention, even if the discrepancy between the control signal and the detection signal is detected, the failure of the solenoid is not judged unless it continues for a predetermined period.

[0014]

【Example】

Example 1. Embodiment 1 of the present invention will be described below with reference to the drawings. 1 and 2 are a flow chart and a timing chart showing a failure determination operation according to the first embodiment of the present invention. The configuration of the solenoid control device according to the present invention is as shown in FIGS. 3 and 4, and only the function of the CPU 11 in FIG. 4 is different.

Next, the operation of the first embodiment of the present invention will be described with reference to FIGS. As before,
The CPU 11 outputs a control signal C which is turned on and off as shown in FIG. 2 based on the operating state, and duty-drives the solenoid 6 by the drive signal A via the drive circuit 13. The control amount of the solenoid 6 at this time is determined by the pulse width of the control signal C, and the pulse width is controlled to several milliseconds or more as described above.

On the other hand, the drive signal A is fed back to the detection circuit 14, and the voltage at one end of the solenoid 6 is input as the detection signal D. At this time, the pulse waveform of the detection signal D has a delay time as compared with the pulse of the control signal C, but this delay time is 1 msec or less and can be ignored. Not shown. Therefore,
If the solenoid 6 is healthy, the detection signal D is as shown in FIG.
As described above, the pulse is a pulse that coincides with the control signal C and is repeatedly turned on and off.

The timer in the CPU 11 generates the sampling signal P and compares the ON / OFF states of the control signal C and the detection signal D for each cycle Tp of the sampling signal P. Now, assuming that the solenoid 6 is broken at time te in FIG. 2 and the detection signal D cannot be obtained, the CPU 11 detects a mismatch between the control signal C and the detection signal D, and executes the failure determination routine in FIG.

First, the disagreement time between the control signal C and the detection signal D is compared with the judgment reference time (setting time) to judge whether the disagreement time is longer than the setting time (step S1). This set time is set to, for example, several milliseconds corresponding to the minimum pulse width of the control signal C. Therefore, in step S1, 1
It is determined whether or not the disagreement state continues for a time corresponding to the pulse width of one time, and if not, the process ends.

In the case of FIG. 2, it is determined in step S1 that the non-coincidence state has continued for the first pulse width T1 (several milliseconds) of the control signal C after the time te. Then, the number of continuous controls in the disagreement state is compared with the determination reference number (set number) n to determine whether the number of continuous controls is equal to or more than the set number n (step S2). The set number of times n can be set to an arbitrary value of 2 or more, for example. If the continuous control count has not reached the set count n, the process ends.

In the case of FIG. 2, when the non-coincidence state continues for the pulse width Tn of the n-th control signal C, it is determined in step S2 that the control has been continued for the set number of times n. At this point, the CPU 11 determines the failure of the solenoid 6 (step S3), sets the failure flag F, and ends the failure determination routine. Thereby, the pulse widths T1 to T
The influence of noise superimposed during n is suppressed, and the failure determination result of the solenoid 6 becomes highly reliable.

Example 2. In the above embodiment, the step S1 of determining the duration of the non-coincidence state of the control signal C and the detection signal D and the step S2 of determining the number of continuous control in the non-coincidence state.
However, if the frequency of noise superposition is low, the failure determination of the solenoid 6 can be performed based on only one of the determination steps S1 and S2.

Example 3. Further, the case where the solenoid 6 drives the transmission 2 of the automatic transmission engine 1 is shown, but it goes without saying that the same can be applied to other devices driven by the duty control of the solenoid 6.

[0023]

As described above, according to the present invention, the control signal and the detection signal are compared at the timing of the sampling signal having a period sufficiently shorter than the pulse period of the drive signal,
Since the failure of the solenoid is determined when the state where the comparison results do not match continues for a predetermined period or more, there is an effect that a solenoid control device that can reliably determine the failure of the solenoid can be obtained.

[Brief description of drawings]

FIG. 1 is a flowchart showing a failure determination operation according to a first embodiment of the present invention.

FIG. 2 is a timing chart showing a failure determination operation according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram showing a general solenoid control device.

FIG. 4 is a configuration diagram specifically showing a control unit of a general solenoid control device.

[Explanation of symbols]

 6 Solenoid 10 Control Unit 11 CPU 13 Drive Circuit 14 Detection Circuit A Drive Signal C Control Signal D Detection Signal P Sampling Signal Tp Sampling Cycle n Number of Settings

Claims (1)

[Claims] 1. A drive circuit for driving a solenoid by duty control, a detection circuit for detecting a voltage at one end of the solenoid as a detection signal, a control signal for the drive circuit, and a control signal for the control signal and the detection signal. In a solenoid control device including a CPU that determines a drive state of the solenoid by comparison, the CPU controls the control signal and the detection signal at a timing of a sampling signal having a cycle sufficiently shorter than a pulse cycle of the drive signal. And a solenoid control device that determines a failure of the solenoid when a state in which the comparison results do not match continues for a predetermined period or more.