Patent GB-676244-A (GB)
Title: Improvements relating to automatic clothes washing machines
IPC: D06F37/30
Filed: 1949-12-13
Abstract: 676,244. Friction clutches. BRITISH THOMSON-HOUSTON CO., Ltd. Dec. 13, 1949 [Dec. 24, 1948] , No. 31989/49. Class 80 (ii). [Also in Groups VIII and XXIX] In a washing machine of the type having a rotatable basket in which the clothes may be spin-dried, a clutch 48, 50 for connecting a driving motor 16 to the basket, a fluid-pressure responsive bellows 57 for actuating the clutch into engaged position upon a predetermined high pressure condition in the bellows, fluid -pressure generating means communicating with the bellows and a discharge port 61 for the bellows controlled by a centrifugally operated valve 60 which closes only when the motor shaft speed reaches a predetermined high value, whereby the clutch cannot be engaged when the shaft speed is below this value, the centrifugally operated valve is arranged to operate independently of the pressure differences on the two sides of the discharge port so that the valve opens whenever the motor shaft speed falls below a predetermined low value. The means for generating fluid under pressure comprises a pump having vanes 28 mounted on an extension 29 of a tubular motor shaft 24. The pump chamber has a cover 32 with outlets into an oil pressure chamber 33 provided by a dished plate 34. The plate 34 has an aperture 37 which serves as a seat for a plunger valve 38 actuated by a solenoid 39. A cup 40 forms an oil sump into which a pump inlet tube 41 reaches. An outlet passage 36 from the pump chamber serves a lubrication duct 21 for pressure lubrication of a bearing member 22 of a gear-casing 14 containing a gear train 15 for oscillating an agitator or other washing device within the basket. An agitator drive shaft 42 has fixed to it one member 46 of an agitator clutch the driving member 45 of which is fixed to the rotor 23 of the motor 16. The agitator clutch is normally retained in and returned to engaged position by the weight of the agitator shaft, and is disengaged by oil pressure from the pump. The spin clutch comprises a driving plate 48 supported by a sleeve 47 which is freely rotatable and axially movable on shaft 42. The driven clutch member 50 is secured to the casing 14 by a flanged cap 51 having slots 52 through which fingers 53 of member 50 extend. Clutch member 50 is held in resilient contact with a brake shoe 55 during agitation by means of a spring 54. Member 48 is secured to the rotor 23 by. means including a, cap 56 and the flexible bellows 57. The clutch parts 48, 50 are normally maintained in disengaged condition by a spring 58 interposed between the cap 56 and a shoe 59 carried by sleeve 47. The bellows 57 is normally full of oil and it is by increasing the pressure of this oil that the clutch parts 48, 50 are engaged and the gear case 14 connected to the rotor for rotation of the basket. The centrifugally operated valve 60 opens to relieve the bellows pressure when the motor speed drops towards the stall point. A valve plug 64 is rotatably housed within the body of the valve 60 and has a passage 65 which, under certain conditions registers with the port 61 in the wall of the valve body, to permit oil to flow out of the bellows. When the rotor 23 rotates counter-clockwise a heavy or weighted arm 66 secured to the valve plug is thrown outwardly by centrifugal force against the action of a spring 67 (Fig. 2). This moves passage 65 away from port 61 and prevents bleeding of oil from the bellows. Operation.-When the solenoid 39 is de-energized so that valve port 37 is open, oil from the vane pump circulates upwardly along passages 44 and into the space between clutch plates 45, 46 and then through orifices 71, 72 into the bellows 57. Although the speed of the motor will ensure that the valve 60 is closed, the oil in the bellows will not be at a great enough pressure to lift clutch plate 46 out of engagement with plate 45 or to raise the clutch plate 48 into engagement with plate 50, because most of the oil output from the pump returns to the sump through ports 31 and 37. Therefore the shaft 42 is being driven by the motor and the gear casing 14 is at rest on the brake shoe 55. To change over from agitation to spinning the solenoid 39 is energized to close the port 37 and the circulation of oil to the sump stopped. The size of the orifices 71 is such as to allow the pressure to increase sufficiently to lift the clutch plate 46 and disengage the shaft 42 from the motor. The oil pressure also expands the bellows 57 (valve 60 being closed) so as to lift the clutch plate 48 into engagement with plate 50. After a short interval when slipping occurs, plate 48 will lift plate 50 free of brake shoe 55 and the gear casing 14 and the spin basket will begin to rotate. If the load of the basket causes the motor speed to drop, the bleed valve 60 will open in proportion to the drop and the bellows will collapse under the influence of the spring 58 until clutch plate 50 is in light contact with the brake 55. At this point slipping between plates 48 and 50 will permit the motor to speed up until the pressure within the bellows again lifts the plate 50. If the motor again slows down the sequence will be repeated until the motor can maintain its operating speed. Specification 619,422 is referred to.