Patent GB-885479-A (GB)
Title: Improvements in ovens having counterbalanced doors
IPC: F24C15/02
Filed: 1958-11-27
Abstract: 885,479. Door counterbalancing devices; push-pull catches; stays. GENERAL MOTORS CORPORATION. Nov. 27, 1958 [Dec. 9, 1957], No. 38295/58. Classes 44 and 65(1). The drop-down door of an oven is counterbalanced by a cable member connected at its ends to the door and the oven frame and passing intermediately over a pulley, the cable member having associated therewith a spring which is stressed as the door is opened and a stop member which checks cable and door movement when the door reaches a horizontal position, one of the members being releasable to allow the door to move to a lower position. The cable member may be connected directly to the oven frame or through the intermediary of the spring. In a first embodiment (Figs. 2, 4) the door 14, pivoted to the oven at 24, is held in the upright closed position by a roller catch assembly 62 in which a bracket 64 pivoted to the oven at 66 is biased by a spring 70 so that the roller 72 carried by the bracket engages a striker 28 on the door. The door is supported as it opens by a cable 34 which passes over a pulley 44 and is fastened to the oven at its other end 110, the pulley being rotatably mounted on a bracket 48 slidable on a track 58 and biased towards the rear of the oven by a spring 52. The door is stopped in the horizontal position when a flange 114 on the pulley bracket 48 abuts a flange 86 on a stop bracket 84 pivoted to the oven at 90. To release the door for pivotal movement from the horizontal to the lower position a finger release lever 92 is provided, pivoted to the oven at 91 and joined to the bracket 84 by a link 100. The lever 92 is turned counter clockwise and simultaneously the tension on the cable 34 is reduced by slightly lifting the door, and the bracket 84 then turns on its pivot until the flange 86 moves out of blocking engagement with the flange 114. The door is then free to pivot to its lower position (Fig. 4). As the door is returned to its closed position the striker 28 exerts a camming action on the upper flange 88 of the bracket 84, and automatically returns the bracket and the lever 92 to their normal positions. The roller catch 62 can also hold the door in a slightly open broil position in which the roller 72 bears on the cam surface 78 of the striker 28, the weight of the door being balanced by the tension in the cable 34. The bracket 84 is positively held in its alternative positions by an overcentre spring 104, and carries a pulley 107 to guide the cable 34. Alternatively, the pulley 107 may be mounted on the same pivot pin as the bracket 84. In a second embodiment (Fig. 6) the cable 34 is joined to the door through an end piece 121 comprising a flat fin 123 and a cylindrical portion 125, and the other end of the cable is connected to a spring motor 126 (not shown). The cable carries a ball stop 130 and passes between a fixed pulley 138 and a vertically slidable pulley 142 loaded by a spring 150 the compression of which can be varied by a two-position pivoted lever 158 having two spring seats 168 and 170, the latter giving the greatest compression. When the door is closed, the end piece 121 is held between the pulleys and the spring abuts the seat 170. The door is arrested in the horizontal position by the engagement of the ball stop 130, with the pulleys, which cannot separate sufficiently to allow for the passage of the ball therebetween. To allow the door to move to the lower position, the lever 158 is turned by means of a finger piece 164, to place the seat 168 in engagement with the spring, and the pulleys can then separate further to enable the ball stop to pass through. On closing, the door abuts the finger piece 164 and automatically resets the lever 158. The door can also be held in a broil position in which the pulley 142 abuts the cam surface 127 at the end of the fin 123 of the end piece 121. In a third embodiment (Fig. 10) the door carries a striker plate 206 pivoted at 204 and biased by a spring 218. The striker plate engages a roller 177 which also serves to guide a cable 190 engaged with a hook 208 on the plate and joined at its other end to a spring 188. The door is held in the horizontal position by the engagement of a stop 192 on the cable with a fixed stop 200, and the cable carries a ball stop 228 at a point which lies just outside the aperture 232 (Fig. 12) in the front panel of the oven when the door is in this position. To lower the door further the cable is forced sideways into a notch 230 in the side of the aperture 232 and the door is then lifted slightly to allow the ball 228 to bear against the sides of the notch. The cable can then be manually disconnected from the hook 208 of the striker plate 206 to free the door. The end portion of the cable beyond the ball 228 hangs. loosely until, it is desired to raise the door.