Patent GB-605051-A (GB)
Title: Improvements in or relating to latch mechanism
IPC: E05B65/00
Filed: 1945-03-16
Abstract: 605,051. Latches. PHILCO RADIO & TELEVISION CORPORATION. March 16, 1945, No. 6679. Convention date, Sept. 29, 1944. [Class 44] The invention provides a latch for use on refrigerator doors which is normally held cocked in the retracted position when the door is opened by the usual handle but which has means whereby on accidental release and subsequent closure of the door the latch is first retracted and then moved to the locking position. According to the invention the latch bolt rocks and slides about a fixed axis in the latch casing under the action of a handle-actuated lever and against the force of a spring the pivot of the lever and its point of connection to the latch bolt forming with the axis, about which the latch bolt slides and rocks, a toggle mechanism so arranged that in the retracted position of the latch bolt the point of connection lies just to one side of the line drawn through the pivot and the axis whereas in the shot position of the latch bolt the point of connection lies at its maximum distance from such line. As a result of this last feature the latch gives an increasing draw-in force to the door as its moves to the final closed position. Stop means limit the projections of the latch at both positions. Fig. 2 shows the latch in fully closed position, Fig. 3 shows the normal closing state, while Fig. 4 shows the closing state when the cocked latch has been accidentally released. As shown the latch comprises a plate member 43 with off-set roller end 46 the member 43 being guided in a sliding- rocking manner by a slot 48 moving over fixed pin 49 and by a pivot joint 42 to a lever 33 pivoted on a fixed pin 32, this lever 33 having an upturned end 34 for engagement by the follower portion 35 of the door handle 36 when the door is to be opened. The end proper of the plate member 43 is shouldered at 32a to abut the fixed pin 32 and so to provide limit positions for the sliding rocking movement of the latch. The latching is effected by the off-set roller end 46 entering the striking plate recess 20. The latch spring 50 acting on the sliding rocking member 43 gives a toggle action pull to draw in the door with an increasing force due to the pivot connection 42 with the lever 33 ; in the closed position the line between the pivot 42 and the fixed pin 32 is parallel to the line of pull on the door so that the spring will cause a maximum draw-in pull to be given. When the handle 36 is operated to open the door the lever 33 is moved to set the pivot connection 42 beyond dead centre as shown in Fig. 3 whereby the latch 43 is moved back and held retracted in the cocked position as defined by a shoulder 52 on the latch body butting on the fixed pin 32. When the door is moved towards closing position the roller end 46 of the latch butts against a face 21 of the striking plate recess thereby transversely forcing the latch beyond the dead centre position whereupon the latch is automatically shot into the latching position. If prior to closing the door the cocked latch had been accidentally released as shown in Fig. 4 then on moving the door towards closing position the roller end, 46 of the latch will engage the cam surface 23 of the striking plate whereby the latch will be moved axially backwards and subsequently shot forward by the spring 50 and its roller end enters the striking plate recess to hold the door closed in the usual manner. The door is provided with the usual resilient sealing gasket 18 and a similar resilient stop 39 may be provided for the interior end of the handle. Instead of the latch being constrained by the lever 33 a pin 42a, Fig. 6, may move in a fixed arcuate slot 60 cut in the plates of the latch case.