Patent GB-764512-A (GB)
Title: Adjustable control devices for automatic vacuum cleaners
IPC: A47L9/10
Filed: 1955-01-04
Abstract: 764,512. Suction cleaners. ELECTROLUX CORPORATION. Jan. 4, 1955 [Jan. 14, 1954; Jan. 29, 1954: April 7, 1954; April 21, 1954], No. 174/55. Classes 8(1) and 8(2) A suction cleaner of the automatic type utilizing a differential pressure diaphragm or equivalent member subjected on one side to the pressure prevailing on the intake side of a filter bag and on the other side to the suction effect of the fan on the other side of the filter bag whereby a predetermined increase in the pressure drop across the filter due to clogging is utilized to operate control mechanism to give a warning of operational inefficiency, is characterized by the provision of an adjustment member accessible from the exterior of the cleaner and operable for varying the pressure drop applied to the diaphragm. A control housing 26 secured to the cleaner casing 10 encloses a differential pressure chamber member 58, a pneumatic power member 60 and an electro-magnetic valve member 62. The member 58 houses the differential pressure diaphragm 66 which is subjected on its upper side to the pressure prevailing in the suction inlet port through a pipe 68 and on its lower side with the pressure prevailing in the housing 10 outside the filter bag through an opening 80 and a pipe 72 which is also connected to the valve 60. The diaphragm 66 carries a contact 88 and is biased to the upper position by a spring 86 which connects the contact 88 to an electrical lead 96. A longitudinally and rotatably moveable member 98 carries a second contact 100 and is electrically connected to a lead 104 and is operable by means of an external knob 112 by means of which the contact 100 may be brought closer to the contact 88. When sufficient pressure differential exists the contacts 88, 100 engage and the solenoid 118 of the valve 62 is energized and the valve 122 opens to connect the pipe 126 to the full suction pressure existing in the pipe 72 The pipe 126 is connected to the chamber 130, Fig. 4, of the power member 60 which chamber is closed by diaphragm 128 the upper side of which is subjected to atmospheric pressure and is connected to a stem 132 which engages a pivoted plate 136 which when the stem 132 moves down releases the catch securing the end cover of the housing 10 which then opens and at the same time withdraws a pin 154 which releases a catch device whereby a spring injects the filter bag from the housing. The effect of the spring 86 towards the end of the downward movement of the diaphragm 66 is increased by means of spring tongues 202. In a modification the electro-magnetic valve 62 is replaced by a valve which is directly actuated by the diaphragm 66. The pressure at which this valve is opened is controlled by bleeding atmospheric air to one or other side of the diaphragm 66 through a manually controlled valve. In a modification of this directly actuated valve the pressure at which the valve will operate is controlled by varying the distance between the stem of the valve and the point of contact with the diaphragm 66. In a further modification the function of the diaphragm 66 is combined with that of the power member. the diaphragm. 66 carrying a slide valve which when the diaphragm has moved sufficiently allows full atmospheric pressure to reach one side of the diaphragm while the other side is subjected to full suction pressure. Opening of the end cover of the housing 10 is arranged to actuate the control switch to switch off the motor. Specifications 682,845, 712,233 and 724,179 are referred to.