GB1398121A - Impact responsive switch device and electric circuit using such device - Google Patents

Abstract

1398121 Inertia switches NISSAN MOTOR CO Ltd 25 May 1972 [28 May 1971 24 June 1971 (2) 17 Sept 1971] 24777/72 Heading H1N An impact responsive switch comprises a receptacle having a cavity therein containing a stationary contact, a conductive element having a flat surface, a rollable contact movably supported on the flat surface and biased to a rest position spaced from the stationary contact, the rollable contact moving from its rest position to connect the conductive element to the stationary contact when subjected to a force of inertia greater than a predetermined magnitude and only when said force is in a direction within a predetermined angular range of less than 180 degrees. Several means of preventing completion of the circuit when the force is outside the prescribed angular range are disclosed in respective embodiments, all of which employ a ball member (27) of electrically conductive ferromagnetic material and a permanent magnet (26) to provide the bias to a rest position. In the embodiments of Figs. 1 to 6 (not shown) the ball is received in a special portion of the cavity having no stationary contact when the impact is not within the desired angle (6). In the case of Figs. 1 and 2 this special portion is a part annular chamber (22b) below the level of the flat surface into which the ball can drop. In Figs. 3 and 4 lower chambers (22c and 22d) are provided on each side of a conductive runway (28), while in Figs. 5 and 6 a generally V-shaped cavity has the stationary contact adjacent the apex and the arms form lateral chambers (29a, 29b) to receive the ball outside angle #. In the embodiment of Fig. 17 (not shown) an adjustable spring- loaded W-section member (51) assists the permanent magnet in holding the ball centrally and also retains the ball when it has been urged to an operated position. The stationary contact may be of resilient metal and split into strips (24a) to provide a cushioning effect. In two embodiments (Figs. 12 and 14, not shown) an additional contact outside the angle # is used to discharge a capacitor (43) in a special circuit (Fig. 15, not shown) and thus prevent actuation should the ball bounce against the stationary contact after impact outside the angle #. In other arrangements to prevent operation by bounce two switches are connected in series and have different rebounds provided by walls of different bulk modulus (Figs. 8A and 8B, not shown), of different radius to provide differing path lengths for the ball (Figs. 10A and 10B, not shown) or by cavities of different shape (Figs. 11A and 11B, not shown).