Zexel Gmbh

Diesel Kiki Co., Ltd.

Airbag Systems Company Ltd

Bosch Electronics Corporation

Masami Okano

Kunihiro Takeuchi

Yasumasa Kanameda

Koichi Miyaguchi

Joerg Heckel

Hideki Ishizuka

Hideyuki Kaneko

Norio Matsuda

Hidekazu Oshizawa

Kyoichi Fujimori

Hiroshi Naganuma

Sadao Ikeya

Ryoichi Harada

The present invention relates to an acceleration sensor which can be provided in a place with extreme ambient temperature variations, for example, near a vehicle engine, and an acceleration detecting system having the acceleration sensor, which are used to control an occupant protection device such as an airbag. In an acceleration sensor ( ), gain of an amplifier circuit ( ) which differentially amplifies outputs of a piezo-electric element ( ) is adjusted by temperature compensation means ( ), and thereby an output-temperature characteristic of the piezo-electric element ( ) is compensated. Also, a capacitor ( ) is inserted in parallel with the piezo-electric element ( ), and thereby a composite capacity is increased. By this, a lower cut-off frequency is set to a lower frequency without increasing resistor values of a bias resistor circuit ( ). The acceleration sensor ( ) is provided in a front part of a vehicle, and its sensor output is received by a receiving circuit ( ) provided in a vehicle room.

Acceleration sensor and acceleration detection system

A control apparatus of an occupant protection device has at least one front acceleration sensor provided in a front part of a vehicle, in addition to a room acceleration sensor provided in a room of the vehicle. Whether the vehicle is in a collision requiring a drive of the occupant protection device is decided based on each of sensor outputs of the room and front acceleration sensors, respectively, and the occupant protection device is driven when the collision is detected based on at least one of the sensor outputs. Since the front acceleration sensor is provided in the front part of the vehicle, the front acceleration sensor detects a collision acceleration early and gives it to the control unit, even in case of a collision, such as the offset or an oblique collision, in which a collision acceleration transmitted to the room acceleration sensor may be weakened. Therefore, the control unit can exactly drive the occupant protection device without causing delay in collision detection.

Control apparatus of occupant protection device

A control apparatus of an occupant protection device has at least one front acceleration sensor provided in a front part of a vehicle in addition to a room acceleration sensor provided in a room of the vehicle. The front acceleration sensor detects an acceleration of the vehicle and gives the control unit a sensor output representative thereof. The control unit, when the sensor output of the front acceleration sensor is a sensor output caused by a collision of the vehicle, detects a variational quantity of the sensor output of the front acceleration sensor based on sensor outputs of the front acceleration sensor at two different time points, and increases an integrated value of an acceleration signal of the room acceleration sensor based on the variational quantity. Then, when the integrated value of the room acceleration sensor exceeds a threshold value, the occupant protection device is driven.

A control apparatus of an occupant protection device detects whether a vehicle is in a collision requiring to drive the occupant protection device based on at least one front acceleration sensor provided in a front part of the vehicle, in addition to a collision detection based on a room acceleration sensor provided in a room of the vehicle. When the collision is detected based on the front acceleration sensor, an integrated value of an acceleration signal of the room acceleration sensor is increased. Since the front acceleration sensor is provided in the front part of the vehicle, the front acceleration sensor detects a collision acceleration early and gives a sensor output to the control unit, even in case of a collision in which a collision acceleration transmitted to the room acceleration sensor may be weakened. By this, since the integrated value of the room acceleration sensor is increased immediately, the control unit can exactly drive the occupant protection device such as an air bag without causing a delay in collision detection.

A control apparatus of an occupant protection device, in addition to a room acceleration sensor provided in a room of a vehicle, has at least one front acceleration sensor provided in a front part of the vehicle. The front acceleration sensor, when detecting a predetermined collision acceleration, gives a detection signal to a control unit. The control unit sets a second threshold value lower than a first threshold value if the detection signal is input, and drives the occupant protection device when an integrated value of an acceleration signal of the room acceleration sensor exceeds the second threshold value. Since the front acceleration sensor is provided in the front part of the vehicle, even when a collision acceleration transmitted to the room acceleration sensor is weakened, the front acceleration sensor detects the collision acceleration early and gives the detection signal to the control unit. By this, since the second threshold value lower than the first threshold value is set, the control unit can exactly drive the occupant protection device, such as an airbag, without causing a delay.

A charged voltage between the ground and a positive pole of backup capacitor 5 and a ground-casing voltage developed between the ground and a casing of capacitor 5 are determined. When the ground-casing voltage is smaller than a first value, it is judged that capacitor 5 has an opened circuit on its positive pole side; when the ground-casing voltage is larger than a second value, it is judged that capacitor 5 has an opened circuit on its negative pole side. A difference between the ground-casing voltage and the charged voltage is divided by the ground casing voltage so that a coefficient is obtained. When the coefficient is outside a predetermined range of values, it is judged that capacitor 5 is poor in capacitance, which makes it possible to determine, even in operation, whether capacitor 5 functions properly.

Method and apparatus for making diagnosis of electrolytic capacitor in

A control system comprises an acceleration sensor for detecting an acceleration of a vehicle, an integral circuit for integrating a signal from the acceleration sensor, and a collision judgment circuit for comparing the integral value with a trigger threshold level and outputs a trigger signal when the integral value, which is increased in a decelerating direction, exceeds the trigger threshold level. A drive circuit of the control system includes an activator of the safety device for a vehicle, and a switching element which is connected to the activator in series and turned on in response to the trigger signal. The control system further comprises a band-pass filter for allowing passage of comparatively high particular frequency band components contained in the acceleration signal, and an adjustment circuit for adjusting the trigger threshold level based on the acceleration components which have passed the band-pass filter.

System for controlling safety device for vehicle

A control system for a plurality of vehicle safety devices has a feeder circuit and a check current supplying circuit. A plurality of actuating elements are arranged in the feeder circuit in parallel relation, and at the same time, they are arranged in the check current supplying circuit in serial relation. When a switching element is turned ON in accordance with a trigger signal coming from a collision judging circuit, an electric current flowing through the feeder circuit is caused to flow through the actuating elements in parallel. The check current flows to the actuating elements in series. The voltage generated between opposite ends of the serial circuit of the actuating elements in the check current supplying circuit is compared with a predetermined allowable range of voltage in a malfunction judging current, and when the voltage between the opposite ends is outside the predetermined allowable range of voltage, a malfunction detecting signal is outputted from the malfunction judging circuit.

Control system for a plurality of vehicle safety devices

A switching boosting circuit including a clock oscillating circuit having a Schmitt trigger inverter, a boosted-voltage inducing circuit which is actuated in a switching-operation mode in response to the output clock of the clock oscillating circuit to induce a boosted voltage, a capacitor which is charged by the boosted voltage from the boosted-voltage inducing circuit to store energy to be supplied to a load, and a feedback path for feeding back current whose intensity corresponds to the load from the capacitor to the clock oscillating circuit. The feedback current acts such that the duty ratio of the switching operation is set to be smaller than a predetermined reference duty ratio, and the feedback path includes a Zener diode for reducing the boosted voltage below a predetermined value.

Switching boosting circuit having internally controlled duty

A system for controlling a safety device for a vehicle has a first and a second switching element connected in series in this order from a power source toward the ground. A condenser is interposed between a connecting point for both the first and second switching element and the ground in such a manner as to be in parallel relation to the second switching element. The actuating element for the vehicle safety device is connected in serial relation to the condenser between the connecting point and the ground. The control system further has an electric current supply control device. This electric current supply control device periodically effects ON/OFF control operations over the first and second switching elements. Each cycle for effecting the ON/OFF control operation over the first and second switching elements includes a time period where the first switching element is in the ON-state and the second switching element is in the OFF-state as well as a time period where the first switching element is in the OFF-state and the second switching element is in the ON-state. Owing to this arrangement, alternating current is supplied to a squib to actuate the vehicle safety device.

A control system for a vehicle safety device includes an acceleration detecting device for detecting the deceleration of the vehicle, an integrating device for integrating the deceleration from the acceleration detecting device, a collision judgment device for comparing the integral value, obtained by the integrating device, with a trigger threshold level so as to judge whether or not a collision has occurred, and for outputting an activation instruction signal when the collision judgment device judges that the collision has occurred, and a drive circuit responsive to the activation instruction signal from the collision judgment device so as to activate the vehicle safety device. The control system further includes a deceleration compensation device for adjusting the trigger threshold level in accordance with the deceleration in such a manner that the trigger threshold level becomes low when the deceleration is large and that the trigger threshold level becomes high when the deceleration is small.

Control system for vehicle safety device

In a control apparatus for actuating a vehicle safety device in response to the specific change in the magnitude of acceleration/deceleration of the vehicle which occurs upon a collision, the output signal from the acceleration/deceleration sensor is processed to obtain detected vehicle speed data relating to the running speed of the vehicle, and the maximum value of a positive-going peak in the change in the detected vehicle speed data is detected to determine a reference level used for discriminating the occurrence of collision. The magnitude of the detected vehicle speed data is compared with the reference level, whereby it is discriminated whether or not a collision has occurred on the basis of the condition of the change in the detected vehicle speed.

Vehicle safety device actuating apparatus with adaptive reference level

A control system for a vehicle safety device includes a pair of acceleration sensing circuits. The outputs of the acceleration sensing circuits correspond to a deceleration of the vehicle in a direction of running of a vehicle, and are in opposite phase with each other. A differential calculation device effects calculation in accordance with the difference between the outputs of the acceleration sensing circuits, so as to cause noises, applied to the acceleration sensing circuits, to cancel each other, thereby preventing an inadvertent activation of the vehicle safety device due to such noises. According to another alternative construction, in order to prevent the inadvertent activation of the vehicle safety device due to the noises, the opposite-phase outputs of the pair of acceleration sensing circuits are integrated by a pair of integrating circuits, and a pair of collision judgment circuits compare the outputs of the integrating circuits with respective threshold levels so as to judge whether a collision has occurred.

A compact watch dog timer circuit which includes a pulse period determining circuit (1) for generating a timer reset pulse if a period of an input pulse from an external machine falls within a tolerance range or beyond an upper limit of the tolerance range and no timer reset pulse if the period falls below a lower limit of the tolerance range; and a timer (2) for generating a signal for restoring the external machine to a predetermined condition when no timer reset pulse is fed from the pulse period determining circuit within a timer period which is set corresponding to the tolerance range.

Compact watch dog timer circuit

A control system for a vehicle safety device includes an acceleration sensing circuit, an analog collision detection system, a digital collision detection system, and a drive circuit which operates the vehicle safety device when the drive circuit simultaneously receives collision detection signals respectively from both of the analog and digital collision detection systems. A microcomputer of the digital collision detection system outputs test pulses to the acceleration sensing circuit, and checks at least one of the output of an integrating circuit of the analog collision detection system and an output of a comparator circuit of the analog collision detection system so as to detect a malfunction of the analog collision detection system, the outputs of the integrating circuit and the comparator circuit being produced in response to the test pulse.

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Higashimatsuyama, Japan

Masami Okano