GB1451444A - Latch assemblies - Google Patents

Abstract

1451444 Latch assembly HOOVER Ltd 9 Oct 1973 [14 July 1972] 33046/72 Heading E2A [Also in Division D1] A latch assembly, which may be incorporated in the fastening mechanism of a washing machine door to prevent opening of the door until the drum has stopped spinning, comprises a locking mechanism movable between fastening and releasing positions, a pneumatically operated valve arranged to hold the latch in its fastening position, the valve having an inlet, an outlet, and a porous wall for controlling the passage of gas through the inlet and/or outlet, and means for triggering the valve to cause gas to pass through the porous wall to permit the latch to be moved to its releasing position when a predetermined amount of gas has passed through the porous wall. The valve may include a flexible wall which carries a porous plug which provides both the inlet and outlet. In Fig. 1, which is a front elevation of an interlock of a washing machine door, and Fig. 2, which is a sectional side view on line A-A of Fig. I, door interlock link 11 is pivotally mounted on-pivot 12, e.g. on the washing machine frame 13. Hooked locking plate 14 is arranged to engage locking pin 15 and is integral with or connected to 11. Link 11 has a central hole 16 aligned with a collar 17 mounted on a shaft 18 which carries a control knob, operation of which controls the machine programme. When the machine is switched on, the control knob is pulled so that shaft 18 carries collar 17 (Fig. 2) into the hole 16. End 20 of interlock link 11 surrounds pin 19 connected to plate bolt 21 which is biased, by spring 23, towards keeper 22 which forms part of the machine. When the machine is switched off, the door may be opened by sliding bolt 21 to the right, which pivots link 11 in an anti-clockwise direction about pivot 12; if the machine is switched on, the door cannot be opened because of the engagement of collar 17 in hole 16. Control cam 25, carried around collar 17, has a periphery with a -constant radius over 270‹ but a decreasing radius for the remaining 90‹, a step 26 which is 10‹ to the right of the vertical in the 'off' position, and a cam follower or roller 27 resting on the smallest radius of the cam in the 'off' position. Cam follower 27 is carried by the limbs of U-shaped portion 28 of interlock arm 29, which is pivotally mounted on the machine frame at 31, carries pin 15, and is biased clockwise towards the cam by spring 32. Valve 33, carried on the end 20A of arm 29, comprises a flexible diaphragm 34 mounted on a stationary timer bracket 35 to form chamber 36 with a flexible wall. The valve inlet or outlet 37, in the form of a sintered brush permits the gradual admission or exclusion of air according to the movement of arm 29. During operation of the machine, arm 29 is moved anticlockwise such that pin 14 is engaged by locking plate 14; at the end of the operation, cam follower 27 will fall down 26 only when sufficient air has been admitted to chamber 36 to permit the clockwise movement of arm 29, i.e. about 40 seconds after the machine has switched off.