Patent GB-1027605-A (GB)
Title: A temperature modulated fluid coupling
IPC: F01P7/04
Filed: 1963-08-01
Abstract: 1,027,605. Hydraulic couplings. SCHWITZER CORPORATION. Aug. 1, 1963 [Aug. 31, 1962], No. 30478/63. Heading F2C. An hydraulic shear type coupling for driving the engine cooling fan of a vehicle has a valve controlling flow of liquid from a reservoir to the working chamber of the coupling which is controlled by means responsive to external and internal temperatures. As shown in Fig. 2 the coupling comprises a casing 10 having cooling fins 10a and having a cover member 18 and a plate 19 secured thereto to form a reservoir 23 and a working chamber 24 within which is mounted a disc 26 fast with a driving shaft 12 which may be connected to the pulley driving the engine water pump. The fan blades may be bolted to the casing 10. A port 35 is formed in the plate 19 to permit flow from the reservoir 23 into chamber 24 under the control of a bimetallic valve member 31 which is welded at 33 to the plate 19. Valve member 31 is responsive to the temperature of fluid in the coupling, and is further controlled by a valve control member 34 overlapping the free end of valve 31 and having spring fingers 34a biasing the control member 34 away from valve 31. Control member 34 is controlled by means of a bimetallic ribbon 38 which is mounted on the cover 18 and disposed in the air stream flowing from the vehicle radiator. The bimetallic ribbon 38 is operatively connected to the control member 34 by a button 42. In operation the reservoir 23 is filled with oil and if the engine is running at relatively high speed at its normal temperature the bimetallic valve 31 is closed by the valve control member 34 to prevent flow into chamber 24. Any oil within chamber 24 accumulates in the peripheral portion of the chamber and flows through a port 45 into reservoir 23, a projection 46 on the plate 19 immediately adjacent to the port 45 aiding the flow through the port 45. The chamber 24 is therefore substantially empty and the fan revolves at low speed. At high temperatures of the engine the temperature of the air flowing through the radiator into contact with the bimetallic ribbon 38 is increased thereby relieving the pressure of the button 42 on the control member 34 which disengages the valve 31. The internal heat generated in the coupling will have increased the internal temperature causing the valve 31 to flex outwardly and open the port 35. As the valve 31 opens, oil will flow through the port 35 into the chamber 24 and will flow outwardly between facing members 28, 51 on the disc 26 and the adjacent walls of chamber 24, and the disc 26 will be driven Whenever the air temperature increases by a substantial degree as, for example, on a warm day when the vehicle stops and the engine idles, the bimetallic ribbon 38 will release the valve control member 34, but since the internal heat generated by slippage is low at idle engine speeds, valve member 31 will remain closed. In the modification shown in Fig 9 the port 35 in the plate 19 between the reservoir and the working chamber is closed by a bimetallic valve 31a riveted to the cover 18 at 33a and is operatively connected to an external bimetallic member 38 by a plunger 53. The couplings are particularly useful in vehicles provided with air conditioning equipment, the condensing element of which is mounted in front of the cooling radiator of the engine so that air is preheated before flowing through the radiator thus affecting the cooling obtained by the radiator.