Sensor Technology Co., Ltd.

Tokin Corporation

Hiroyuki Sada

Hiroshi Moriyama

Takeo Shiozawa

Akihiko Kuroiwa

Naoharu Yamamoto

Yasunori Ohtuki

Noriyuki Gotoh

Collision detection device

Crash sensor

An electronic crash sensor which can operate appropriately in response to any form of crash of any vehicle, more especially to a high speed oblique or pole crash of a vehicle which has a less rigid body or to a compound crash which is compound of various forms of crash, to say nothing of a high speed oblique or pole crash of a vehicle which has a normal rigid body. An input acceleration waveform from an accelerometer is processed to peak cut any portion thereof lower than a predetermined value. Then, the value obtained by the said peak cutting is time integrated. Then, a time integrated value of a predetermined function is subtracted from the value obtained by the said time integration. Then, the value of the acceleration waveform thus obtained is firstly compared with a predetermined time function value, and when the former is higher than the latter, a triggering signal is developed, while a diffrential of the said values of the acceleration waveform per a predetermined time value is secondly compared with a predetermined value, and when the former is higher than the latter, a triggering signal is developed. And further, the said first comparing means and the said second comparing means are connect with a trigger circuit to trigger a passenger protecing apparatus called an air bag by way of a connecting means.

To detect an impact due to a shock with high precision and stability, a shock sensor is employed which provides a sufficiently long closure interval of a contact of a reed switch (1) enough to carry out signal processing. A gap between an outer surface of a magnet (2) and an inner wall (8) of a housing (7) defining a passage for the magnet (2) comprises a first gap (G1) between a stationary position and an activating position and a second gap (G2) between the activating position and a stop position. The inner wall (8) is formed so that the first gap (G1) is greater than the second gap (G2). The velocity of the magnet (2) is lower when travelling in the second gap (G2) than the velocity in the first gap (G1) because air resistance is greater in the second gap (G2). Accordingly, the closure interval is increased. Alternatively, the closure interval of the contact of the reed switch (1) is adjusted by first and second coil springs (3, 49) which independently urge first and second magnets (2, 48) in an anti-impact direction, respectively. To cope with various collision modes, spring constants (k1, k2) of the first and the second coil springs (3, 49) and masses (m1, m2) of the first and the second magnets (2, 48) are selected so that the velocity of shock-responsive movement is different between a first group comprising the first magnet (2) and the first coil spring (3) and a second group comprising the second magnet (48) and the second coil spring (49).

Shock sensor

An electronic crash sensor which can operate appropriately in response to any form of crash of a vehicle. An input acceleration waveform from an accelerometer is first processed to peak cut any portion thereof lower than a predetermined value. Then, a value obtained such peak cutting is time integrated. Then, a time integrated value of a predetermined function is subtracted from a value obtained by such time integration. Then, the value of the acceleration waveform thus obtained is compared with a predetermined time function value, and when the former is higher than the latter, a triggering signal is delivered to a trigger circuit to trigger operation of a passenger protecting apparatus such as an air bag of the vehicle.

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Kobe, Japan

Hiroyuki Sada