GB1424025A - Fluid shock sensor - Google Patents

Abstract

1424025 Measuring shocks electrically ASAHI KASEI KOGYO KK 18 April 1973 [24 April 1972 29 May 1972 30 Oct 1972] 18640/73 Heading G1N [Also in Divisions F2 and G3] Apparatus for measuring mechanical shocks is exemplified by the embodiment of Figs. 1 and 3 wherein a block 1 has a closed fluid path made up of horizontal channels 2, 5 and vertical channels 3, 4 so that a shock force 20 displaces mercury 6 in the channel 2 between the poles 8a, 8b of a U- shaped magnet 8, 9 and generates a voltage between electrodes 10, 11 whose amplitude is indicative of the rate of flow of mercury and hence proportional to the magnitude of the shock. The flow-path contains restrictions 16, 17 which act as a high frequency filter to reduce noise in the output signal, and to produce a sharp cut off in the electrical signal. In an embodiment according to the invention, the flow-path contains a threshold device, e.g. a spring-biased valve 24 Fig. 6 which closes the connection between channels 2 and 4 to shocks below an adjustable value. Other mechanical threshold devices are described such as gravity devices, a float member, magnetic members, a flexible or rupturable membrane, or a porous member utilizing the surface tension of the mercury 6 to prevent flow with small shocks. Facilities are provided to prevent the accumulation of mercury 6 beyond the threshold device. To sense shocks in a range of directions a plurality of vertical channels 3 are provided over an angular range, joined to the right hand part of the apparatus shown in Fig. 1 by parallel horizontal branches 2, 5, the branches 2 1 -2 8 Fig. 17 containing convolutions or other means which restrict fluid-flow from the centre 60 to the outer connections 65 but allow free liquid flow in the other direction. The liquid paths may contain different fluid-flow restrictions to produce different desired sensitivities to shock forces in different directions. An electrode may be assembled in each corner of the lid of block 1 to be selectively contacted by the mercury 6 when the unit is inclined, to indicate the direction of the inclination. The sensor may be mounted on a vehicle and used to inflate a safety bag when the vehicle is involved in a collision. The electrical signal voltage is fed through a threshold device and amplified to fire a thyristor which energizes an ignition charge to release gas to the safety bag.