Patent GB-1457737-A (GB)
Title: Key-operated locking mechanism
IPC: B60K15/04
Filed: 1972-10-17
Abstract: 1457737 Locking petrol caps PRESSWORK-COMPONENTS Ltd 17 Jan 1974 [17 Oct 1972 47699/72 Heading B8T [Also in Division E2] A key-operated locking mechanism, e.g. for a fuel tank cap, has a rotatable shield which is resiliently-loaded into a key-baulking position where it obscures a key-opening, the shield being itself adapted to receive the key so that it can be moved by the key to a position where it allows the key to enter the key-opening As shown, a cap 10 accommodates a locking member 24 adapted to engage an inturned lip on the end of a fuel tank filler-pipe, and is formed with an aperture 29 which receives the boss 31 of a circular shield plate 30 having rectangular holes 32 and overlying a circular plate 34 also provided with rectangular holes 36 in positions corresponding to the holes 32. The plate 34 is formed with a skirt 38 having tongues 40 which engage in a slot 42 of a member 44, and the shaft of a pin 46, having a head 48 provided with notches 50 aligned with the holes 36, passes through the member 44, a flat spring 52, a reciprocatable latch member 54, the plate 16 and the locking member 24. Inclined projections 56 of the spring 52 engage in the slot 42 of the member 44 and the underside of the spring engages the member 54, which is formed with a slot 58 and a side slot 62 in which is engaged a pin 66 of the member 44, and extends through a hole 64 in the plate 16. In the normal projected position of the member 54, the cranked end 62 thereof engages under the lip of the filler pipe to lock the filler cap in position. On assembly, the holes 32 and 36 are angularly displaced from each other by a torsion spring 68 acting between the plates 30 and 34. The key has a bifurcated end providing limbs 92 each formed with an inward projection 94. The key is inserted into the holes 32 of the shield plate 30 and rotated until the holes are in alignment with the holes 36, when the projections 94 can be pushed through the notches 50 of the pin 46 to engage in the slot 42 of the member 44 whereby the projections 56 are forced out of the slot. Rotation of the key then causes rotation of the member 44 and plates 30, 34, and the pin 66 describes an arcuate path and thereby moves the latch member 54 inwardly to remove the cranked end 62 thereof from engagement with the lip on the fuel pipe to unlock the cap; the key cannot be removed from the cap since the projections 94, in the unlocked condition of the device, lie beneath the head 50 of the pin 46. Replacement of the cap on the filler pipe and rotation of the key to a locking position causes the latch member 54 to re-engage the lip on the filler pipe and withdrawal of the key through the notches 50 of the pin 46 allows the projections 56 to re-engage the slot 42 and the plate 30 to return under the action of the spring 68 to the initial position thereof. In a modification, the latch member 54 is replaced by a locking bar (104) Fig. 4 (not shown) having hooked ends (110) and which, when rotated by the key to the locking position locate under outwardly turned lips on the filler pipe. The key may have a lever formation on one or both limbs thereof.