GB914580A - Improvements in or relating to drives - Google Patents

Abstract

914,580. Cooling cylinders. THOMPSON RAMO WOOLDRIDGE. May 31, 1960, No. 19251/60. Class 7(2) [Also in Groups XXVI and XXIX] An hydraulic coupling 1, Fig. 1, for the fan 3 of an internal combustion engine 2 comprises a driving element 18, Fig. 2, and a driven element 20 separated by a coupling space of constant volume, and a temperature-responsive expansible and contractible means for displacing fluid into and out of the coupling space. The drive may be transmitted hydrodynamically or, as described, by the viscosity of the fluid. The driving element 18 forms an end wall of a housing 28 which is mounted on a sleeve 10 driven by a belt 68 from the engine 2 and has a wall 32 secured by a bellows 30 to its other end wall 24 in contact with the air or water cooling system of the engine. The heat may be transmitted by conduction or radiation; in the latter case, the wall 24 is preferably painted flat black. The bellows contains a bi-metal element or a fluid, such as gas or alcohol in liquid 36 and vapour 38 form, responsive to temperature so that, when heated, it expands to displace a viscous liquid 26 formed into a ring by the centrifugal effect of rotation of the housing into the coupling space between the wall 18 and the driven element consisting of a disc 20 secured to a shaft 14 to transmit torque to the fan. Depending on the quantities of fluid in the housing and bellows, an increase in centrifugal force caused by increased rotation of the housing may compress or expand the bellows to vary the quantity of fluid in the coupling space. The movement of the bellows may be effected against spring, atmospheric or gaseous pressure. In another embodiment, the driving element consists of a disc 142, Fig. 6, keyed to a shaft 126 which is belt-driven from the engine and supports a housing 144 carrying the fan 103; the disc may have free or fixed axial connection to the shaft. The disc extends into a coupling space between surfaces 166, 167 on the housing which is formed with a recess 160 receiving an annular, radiallyextending chamber 162 of brass or plastic material containing a temperature responsive fluid such as acetate, alcohol or the fluid known under the Registered Trade Mark "Freon". Expansion or contraction of the chamber controls the amount of fluid, such as silicone or petroleum oil, between the surfaces 166, 167 and hence the torque transmitted by the coupling. The housing is shaped to form a space 168 and centrifugal force acting on the fluid in the space, between the surfaces 166, 167 and in the recess 160, acts on the chamber 162 to vary its volume and the amount of liquid between the surfaces. In a further embodiment, the annular chamber 162 extends axially of the coupling to reduce the effect of centrifugal force. Cooling fins 178, 180, 182 are provided on the housing.