JPH04143146A - Diagnosis circuit for crew protection device for vehicle - Google Patents

Abstract

PURPOSE:To prevent the occurrence of accidental explosion as well as to check out operations similar to actual ones by detecting possible failures on an operation judging circuit based on pseudo collision signals in place of acceleration signals, and carrying out a check program at the time of diagnosis with power supply turned on after an acceleration switch 'ON' has been affirmed. CONSTITUTION:When an ignition switch 33 is turned on, an ignition signal (a) is supplied to a diagnosis circuit 36. And when it is detected by a threshold limit circuit 49 that an acceleration circuit 46 is turned off, a detecting signal (b) is forwarded to the diagnosis circuit 36. This thereby allows the diagnosis circuit 36 to output a signal (c) operating a change-over switch 39, so that a pseudo program signal is outputted to a D/A converter 37. Furthermore the D/A converter circuit 37 supplies a pseudo collision signal (d) to the change-over switch 39. After signals from the change-over switch 39 passed through a high bypass filter 40, have been integrated by an integrator 41, the signals are allowed to pass through the threshold limit circuit 42 and an amplifier 43, so that an ignition diagnosis signal (c) is thereby diagnosed by the diagnosis circuit 36.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention allows a diagnostic circuit to proceed with a check program containing a trigger signal when the power supply voltage is turned on, and while the check program is in progress, an ignition device is activated. The present invention relates to a diagnostic circuit for a vehicle occupant protection device provided with means for preventing the triggering of the vehicle.

[Conventional technology]

An example of a conventional diagnostic circuit for an air bag system is shown in FIG. 2, for example.

In the figure, 1 is a trigger device, and this trigger device 1 has an acceleration sensor 2 that outputs an electrical signal when an acceleration of a predetermined value or more is input, and an output signal from the acceleration sensor 2 that is caused by hitting an obstacle. an identification means 3 for discriminating whether the cause is an accident, sudden braking, or hitting a stone, and emitting an output signal when it is determined that the cause is an accident; and an output stage to which the output from the identification means 3 is supplied. It is composed of a transistor 4. 5 is a resistor connected in parallel to the output stage transistor 4, and 6 is this resistor 5.
The ignition device 6 is connected in series with the ignition device 6, and the ignition device 6 is grounded through a parallel circuit of a resistor 7 and a transistor 8. 9.10 is a threshold value switch connected between the ignition device 6 and the resistor 7; the output side of this threshold value switch 9 is connected on the one hand to the monitoring light 12 via an OR gate 11; On the other hand, it is connected to the input side of the first current source 14 via the AND gate 13. The output side of the threshold switch 10 is connected on the one hand via an AND gate 15 to the input side of a second current source 16 and on the other hand via an inverter 17 to the other input side of the AND gate 13 and to the input side of the AND gate 18. It is also connected to the input side of the AND gate 19. The output side of the AND gate 18 is connected to the input side of the third current source 20. The output side of the AND gate 19 is connected to the base of the transistor 8. The terminal 21 is connected on the one hand via a threshold switch 22 to a further input of the AND gate 19 and on the other hand via an inverter 23 to a further input of the OR gate 11 and to the control input of a discharge current source 24. There is. The output sides of the current sources 14 and 16° 2o and the input side of the discharge current source 24 are grounded via a capacitor 25. Current source 1
4.16, 20, 24 together with the capacitor 25 form an integrator 26 with three integration constants.

This integrator 26 is further connected to a threshold switch 27.28°29
Together with this, they form a timed element system. Threshold switch 27
The output of is connected on the one hand to another input of an AND gate 15 and on the other hand via an AND gate 30 to the input of the identification means 3 of the trigger device 1. Threshold switch 2
The output side of 8 is connected on the one hand to another input side of AND gate 18 and on the other hand to AND gate 3 via an inverter 31.
connected to another input of 0. The output of the threshold switch 29 is connected on the one hand to a further input of the AND gate 19 and on the other hand via an inverter 32 to a further input of the OR gate 11 .

Next, the operation will be explained.

As soon as the supply voltage is switched on, its value is tested by the threshold switch 22. If the supply voltage is below the minimum permissible value, the threshold switch 22 will not react and the AND gate 19 will remain cut off, while the inverter 2
A discharge current is injected via 3, which prevents the capacitor 25 from charging. This threshold switch 22 also serves to shut off the transistor 8 in the event of a subsequent drop in the supply voltage, thereby avoiding false triggering due to a drop in the supply voltage.

The second program phase begins by activating the threshold switch 27 and supplying the identification device 3 with a trigger signal for a simulated trigger via the AND gate 30 . When the identification circuit 3 and the output stage transistor 4 function normally, the output stage transistor 4 becomes conductive after a predetermined time delay. As a result, threshold switches 9 and 10
The voltage value on the input side jumps to almost the value of the full supply voltage.

By exceeding the threshold value of the threshold value switch 10, a high level signal is generated at the output side of the double open value switches 9, 10.

The current source 14 is switched off and the current source 16 is switched on. Capacitor 25 is further charged in accordance with the current supplied by current source 16 until the threshold value of threshold switch 28 is reached.

The second program phase ends and the simulated trigger signal is interrupted by the inverter 31. Current source 16, like current source 14, includes a limiting device that limits the charging of capacitor 25 to a value just above the threshold of threshold switch 28. In normal functioning, the output stage transistor 4 should therefore switch off again after a predetermined time delay, so that the voltage drops to half of the supply voltage. For this purpose, a low level signal is again generated at the output of the threshold switch 10, which cuts off the current source 16 and also switches on the current source 20 via the inverter 17 and the AND gate 18. Depending on the current supplied from the current source 20, the capacitor 25 is further connected to the threshold switch 2.
It is charged until the threshold of 9 is reached. The output signal of the threshold switch 29 causes the transistor 8 to remain in this state from this point until the supply voltage is cut off or falls below the threshold of the threshold switch 22, and then is switched into conduction via the AND gate 19. The test program is now finished and the trigger device is ready for operation.

[Problem to be solved by the invention]

However, in such a conventional air pack system diagnostic circuit, the circuit configuration is such that the transistors 4 and 8, which serve as acceleration switches upstream or downstream across the ignition device 6, are not electrically turned on at the same time. Therefore, there were problems in that sufficient circuit diagnosis could not be carried out, or that if a transistor upstream or downstream of the ignition device failed, the air pack system would malfunction and an accidental explosion could not be prevented.

This invention has been made to solve the above-mentioned problems, and it is possible to prevent an accident by executing a check program after confirming that the acceleration switch is on at the time of diagnosis when the power is turned on.

An object of the present invention is to provide a diagnostic circuit for a vehicle occupant protection device such as an air pack system, which performs a check similar to actual operation.

[Means to solve the problem]

The first claim includes an acceleration switch in which a dummy resistor is connected in parallel between the terminals of a power source, an ignition device for activating a vehicle occupant protection device, and a collision waveform determined based on a detection output from an acceleration sensor. A vehicle occupant protection device comprising an operation determination circuit for activating the ignition device, wherein the vehicle includes pseudo signal generating means for supplying a pseudo collision signal to the operation determination circuit in place of the detection signal from the acceleration sensor. This system is equipped with a diagnostic circuit for the passenger protection system.

The second claim includes an acceleration switch in which a dummy resistor is connected in parallel between the terminals of a power source, an ignition device for activating a vehicle occupant protection device, and a collision waveform determined based on a detection output from an acceleration sensor. In a vehicle occupant protection device comprising an operation determination circuit for activating the ignition device, a threshold value for determining whether a potential at a connection point between the acceleration switch and the ignition device is below a predetermined value when the power is turned on. A vehicle occupant protection device comprising: a circuit; and pseudo-signal generating means for supplying a pseudo-collision signal to the operation determination circuit in place of the detection signal from the acceleration sensor when the potential at the connection point is below a predetermined value. It is equipped with a diagnostic circuit.

[Effect]

The diagnostic circuit for an air pack system according to the first aspect is configured to detect a failure in the operation determining circuit 45 by supplying a pseudo collision signal from the pseudo signal generating means to the operation determining circuit instead of the detection signal from the acceleration sensor. This is what I did.

The diagnostic circuit for an air pack system in the second claim determines whether or not the potential at the connection point between the acceleration switch and the ignition device is below a predetermined value when the power is turned on, and when the potential is below the predetermined value, A pseudo collision signal from the pseudo signal generating means is supplied to the operation judgment circuit instead of the detection signal of By determining whether the value is below the value, it is possible to confirm that no explosion has occurred due to the ignition device.

〔Example〕

Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention.

First, to explain the configuration, in Fig. 1, 32 is a power battery, 33 is an ignition switch, 34 is an ignition power supply circuit having a step-up/high voltage converter, 35 is an ignition switch interface, 36 is a diagnostic circuit consisting of a CPU, etc., and 37 is a diagnostic circuit including a CPU. A D/A converter converts the output from the diagnostic circuit 36 into digital/analog, 38 is an acceleration sensor that operates based on an acceleration signal, and 39 is the diagnostic circuit 3
6 is a changeover switch to which the pseudo collision signal d from the D/A converter 37 is supplied based on the changeover signal C from 6; 40 is a bypass filter that cuts acceleration signals caused by normal operation;
41 is an integrator, 42 is a threshold circuit that turns on when the output signal of the integrator 41 exceeds a threshold, 43 is an amplifier to which the output signal of the threshold circuit 42 is supplied, 44 is a diagnostic dividing resistor, a changeover switch 39, a bypass Filter 40, integrator 41, threshold circuit 42, amplifier (switching transistor) 43
The operation determination circuit 45 is configured.

46 is an acceleration switch in which a dummy resistor 47 is connected in parallel between the terminals of the ignition power source 34; 48 is an ignition device for inflating an air pack (not shown); 49 is an acceleration switch 46
This threshold circuit 49 detects the potential at the connection point between the acceleration switch 46 and the ignition device 48. The threshold circuit 49 executes failure diagnosis after confirming that the acceleration switch 46 is turned off.

Next, the operation will be explained.

When the ignition switch 33 is turned on, the ignition signal a is supplied to the diagnostic circuit 36.

Further, since a small check current flows from the ignition power supply circuit 34, a voltage is generated at the connection point between the acceleration switch 46 and the ignition device 48. When the threshold circuit 49 determines that the acceleration switch 46 is off, the diagnostic circuit 3
6, an acceleration switch off detection signal is sent. Therefore, the check program in the diagnostic circuit 36 runs, and based on the acceleration switch off detection signal, the diagnostic circuit 36 outputs a signal C that activates the changeover switch 39, and then the diagnostic circuit 36 converts the pseudo program signal into a D/A converter. output to the device 37. This D/A conversion circuit 37 supplies a pseudo collision signal d to a changeover switch 39, and a signal from this changeover switch 39 that has passed through a bypass filter 40 is integrated by an integrator 41, and further passes through a threshold circuit 42 and an amplifier 43. The diagnostic circuit 36 diagnoses the ignition diagnostic signal e.

〔Effect of the invention〕

As explained above, according to the invention of claim 1, the configuration includes an acceleration switch in which a dummy resistor is connected in parallel between the terminals of a power source, an ignition device for operating a vehicle occupant protection device, and a signal from an acceleration sensor. an operation determination circuit that determines a collision waveform based on the detection output and activates the ignition device;
In place of the detection signal from the acceleration sensor, a pseudo-collision signal is supplied to the operation judgment circuit to determine whether there is an abnormality in each part, and the pseudo-signal generating means is provided. By executing the check program after confirming that the switch is off, it is possible to prevent an accidental explosion and also to be able to perform a check that is close to the actual operation.

According to the invention of the second claim, the configuration includes an acceleration switch in which a dummy resistor is connected in parallel between the terminals of a power source, an ignition device for activating a vehicle occupant protection device, and a collision based on a detection output from an acceleration sensor. an operation determination circuit that determines a waveform and activates the ignition device; a threshold circuit that determines whether a potential at a connection point between the acceleration switch and the ignition device is below a predetermined value when the power is turned on; pseudo-signal generating means for supplying a pseudo-collision signal to the operation determination circuit in place of the detection signal from the acceleration sensor when the potential at the connection point is below a predetermined value to determine abnormality in each part; As a result, when diagnosing when the power is turned on, the check program is executed after confirming that the acceleration switch is off, thereby preventing accidental explosions, and making it possible to perform a check that is close to the actual operation. In addition to detecting a failure, it is also possible to confirm that no explosion has occurred due to the ignition device by determining whether the potential at the connection point between the acceleration switch and the ignition device is below a predetermined value.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a diagnostic circuit for an air pack system according to an embodiment of the present invention, and FIG. 2 is a block diagram showing an example of a conventional diagnostic circuit for an air pack system. 36... Pseudo signal generation means, 38... Acceleration sensor, 45... Operation determination circuit, 46... Acceleration switch, 48... Ignition device.

Claims (2)

[Claims] (1) Determine the collision waveform based on the detection output from the acceleration switch (46) with a dummy resistor connected in parallel between the terminals of the power supply, the ignition device (48) that activates the vehicle occupant protection device, and the acceleration sensor. In a diagnostic circuit for a vehicle occupant protection device comprising an operation determination circuit (45) for activating the ignition device, a pseudo collision signal is sent to the operation determination circuit (45) in place of the detection signal from the acceleration sensor. Pseudo signal generating means (3
6) A diagnostic circuit for a vehicle occupant protection device. (2) Determine the collision waveform based on the detection output from the acceleration switch (46) with a dummy resistor connected in parallel between the power supply terminals, the ignition device (48) that activates the vehicle occupant protection device, and the acceleration sensor. In a diagnostic circuit for a vehicle occupant protection device comprising an operation determination circuit (48) for activating the ignition device, when the electric potential at the connection point between the acceleration switch and the ignition device is equal to or less than a predetermined value when the power is turned on; a threshold circuit (49) for determining whether or not there is a collision; and a threshold circuit (49) for determining whether or not a collision occurs;
5) A diagnostic circuit for a vehicle occupant protection device, characterized in that it is provided with a pseudo signal generating means (36) for supplying the signal to the circuit to determine abnormality in each part.