Patent GB-770943-A (GB)
Title: Improvements relating to automobile door latches
IPC: E05B65/32
Filed: 1955-06-06
Abstract: 770,943. Door latches. GENERAL MOTORS CORPORATION. June 6, 1955 [June 23, 1954; Sept. 16, 1954], No. 16158/55. Class 44. An automobile door latch comprises a body plate 15 adapted for mounting parallel to the jamb face of the door, a latch bolt 18 pivoted about an axis at right angles to said plate, a pivoted detent 25 to block pivoted unlatching movement of said bolt, and a latch-operating link 43 for withdrawing the detent from blocking position; said link being mounted by a pivotal connection incorporating a slot 44 to permit sliding movement of the link, so that the link is capable of pivotal movement between an operative position, in which the sliding movement of the link is adapted to withdraw the detent, and an inoperative position in which the sliding movement of the link is idle and ineffective on the detent. The latch bolt 18 has a plurality of symmetrical and equally spaced teeth 19 and is secured to a shaft 20 which is rotatably mounted on the plate 15, the shaft 20 also carrying a cam 22 having a plurality of equally-spaced asymmetrical teeth 24. The bolt is partially contained in a housing 21 riveted to the outer surface of the plate 15 and the cam 22 is on the inside of the plate. The cam teeth 24 are engaged by the detent 25 which when engaged with the teeth allows the cam and hence the bolt to rotate only in a counter-clockwise direction as shown in Fig. 2, the detent 25 being pivotally mounted on a stud 26 which projects from the plate 15 and loaded by a coil-spring 27 into engagement with the cam 22. When the detent is in engagement with the cam the door can be closed since the detent rides over the teeth of the cam during closing movement of the door but in order to open the door the detent must be removed from the cam teeth. This is accomplished by means of a lever 31 which is pivotally mounted on a stud 32 on the plate 15 and which has an arm 33 engaging a recess 34 in the detent. The lever 31 also has an arm 36 by which the lever may be moved through a bell-crank lever 61 and a link 59 from the inside handle of the door. The lever 31 has another arm 35 by which the lever may be moved from the outside of the door. This is accomplished through the link 43. The link is mounted on the plate 15 by means of a stud 45 which extends through the slot 44 in the link, a roller bearing 46 being interposed between the slot and the stud. The link 43 is slidably moved by means of a push-button which through a push-rod engages a flange 42 on the outer end of the link 43. The link 43 is formed with two arms 51, 52 separated by a slot 53 and the arm 52 engages the end of the arm 35 of the lever 31 which in turn disengages the detent from the cam 22. The free end of arm 51 is bent to form a tab 55 which is positioned between spaced prongs 73, 74 on a trip lever 71 which is pivotally mounted on a flange 16 of the plate 15. The trip lever is biased to one or other of two positions by an over-centre spring 77 and it is moved to either position by a keyoperated barrel lock on the outside of the door through a lever 81 and link 80, the lever 81 being straddled by an actuator of the barrel lock. When the trip lever 71 is in one position the arm 52 of the link 43 can engage the arm 35 of the lever 31 so that the door can be unlocked by the outside push-button. When the trip lever is in its other position the link 43 is rotated about its pivot by the engagement of the prongs 73, 74 with the arm 51 and in this position of the link 43, the end of the arm 35 falls in the slot between the arms 51 and 52 so that movement of the link 43 by the outside push-button does not move the arm 35 and the door cannot then be unlocked by the outside push-button. The trip lever 71 can also be moved to the latter position from the inside of the car by means of a garnish moulding button which is connected to the trip lever through an actuating-rod 85 and a bell-crank 86. To prevent the door being automatically locked when closed the arm 52 is provided with a projection 54 which is engaged by a projection 98 on the detent 25 during closing of the door and this engagement of the two projections moves the link 43 to the position in which its arm 52 is in engagement with the arm 35 on the lever 31. If, however, the garnish moulding button and the outside push-button are both depressed the link 43 is moved so that the projections 54 and 98 do not engage and the door is then automatically locked when closed. In a modification the link 43 may be divided into two parts, one of which is slidable in the slot 44 which is then in the plate 15. The slidable link part carries the flange 42 engageable by the outside push-button and the other part is pivoted to the slidable part and includes the arms 51, 52 and the projection 54. In another modification the detent lever is combined with the lever 31. To prevent actuation of the outside push-button by an object striking the side of the vehicle or by overturning of the vehicle a overhanging portion is provided on the outside handle which contains the push-button.