Theft-preventing device for automobiles

Claim 2

A theft-preventing device of automobiles mounted on a steering shaft casing and comprising: a key; a key-operated unit consisting of a steering shaft locking means to lock a steering shaft of an automobile when the key is at a lock position, and an alarm switch having an alarm switch circuit to be completed unless said steering shaft is locked; a door switch mounted on a door of the automobile and having a door switch circuit to be completed on each opening said door; an alarm means having a series-connected electric power source; and an electric loop circuit including said alarm means, said door switch circuit, said alarm switch circuit, and said power source, all connected in series; whereby alarm sounds are produced whenever said door is opened without locking the steering shaft, regardless of the operative position of said key.

Claim 3

A theft-preventing device according to claim 1 and further comprising an engine switch mounted on said key-operated unit and having an engine switch circuit to be closed when said key is at a garage position and a stop position, said engine switch circuit being inserted in series to said loop circuit, whereby alarm sounds are produced whenever said door is opened without locking the steering shaft while holding the key to the garage and the stop position.

Claim 4

A theft-preventing device according to claim 1, wherein said steering shaft has a sleeve with a notch secured thereto, and said locking means of the key-operated unit has a stop claw engageable with said notch when said key is at said lock position.

Claim 5

A theft-preventing device according to claim 3, wherein said key-operated unit has a stop claw connected to a hollow actuating member secured at the upper end thereof, a rotor fitted in the inner space of said actuating member and having a shoulder portion adapted to receive the inner wall of the upper edge of said hollow actuating member, said rotor further having a diametrical groove, a plunger slidably fitted in said diametrical groove and having a stopper fitted in said plunger while being biased away from the plunger, and a spring inserted between the top surface of said actuating member and inner surface of the top of housing of said key-operated unit; whereby, with said key held at the lock position, the upper end of the actuating member engages said shoulder of said rotor so as to occupy a lowered position to allow engagement of the stop claw with the notch of the steering shaft to lock the steering shaft; when said key is held at a garage position, the middle point of the nonshouldered peripheral edge portion of the rotor holds said actuating member at a raised position to keep the stop claw awaY from the notch of the steering shaft, so as to unlock said steering shaft; with said key held at a drive and a start position, intermediate points of the nonshouldered peripheral edge portion of the rotor hold said actuating member at said raised position to keep the steering shaft unlocked; and with said key held at a stop position, the tip of said key holds the lower surface of said stopper, so that the upper portion of said actuating member is held at said raised position by said plunger, while upon removal of said key, the plunger is released from said key to allow the movement of said stop claw toward said steering shaft for locking the steering shaft.

Claim 6

A theft-preventing device according to claim 1, wherein said alarm switch has a spindle, a movable contact secured to said spindle, a stationary contact secured to the housing of said alarm switch, a check ball located at the lower end of said spindle and engageable with a certain predetermined recessed portion of said stop claw, and a spring biasing said spindle toward said stop claw.