Patent GB-473270-A (GB)
Title: Improvements in hydraulic brakes and clutches
IPC: F16D57/04
Filed: 1936-02-06
Abstract: 473,270. Hydraulic brakes. HEENAN & FROUDE, Ltd., and WALKER, G. H. Feb. 6, 1936, No. 3571. [Class 103 (i)] [Also in Groups XXIX and XIX] Hydraulic apparatus of the kind comprising primary and secondary vaned members forming a hydraulic clutch or coupling or an absorption brake or absorption dynamometer is provided with a valve in the outlet therefrom controlled by a diaphragm, piston or the like, the pressure on the operative surface of which is varied automatically with variations in speed of the primary element of the apparatus, any increase in speed of the latter and consequently increase in pressure on the diaphragm or piston tending to move the valve towards its closed position. A disc or mushroom valve A, Fig. 1, arranged in the outlet B, C from the working chamber of the apparatus is carried by a rod a secured to a diaphragm D dividing a vessel E into upper and lower compartments e<1>, e<2>, a pump F is provided, which is driven at a speed proportional to that of the primary element of the apparatus either by being geared to or having its impeller mounted on the shaft thereof; the chamber e<1> is connected directly to the delivery side f of the pump and indirectly to the suction side f<1> of the pump through an adjustable valve G, in parallel with a relief valve K, and a strainer H ; an expansion chamber L is preferably provided; the chamber e<2> communicates either directly with atmosphere or preferably with the suction side of the pump through the strainer. The valve A is thus acted on in opposite directions by the pressure of the liquid in the working compartment and by the pressure in the compartment e<1>. The initial setting of the valve A and thereby the degree of filling of the apparatus is determined by adjustment of the valve G, the valve A setting itself in the position in which the outlet rate equals the inlet rate. Any temporary increase in the inlet rate causes the valve A to open temporarily until the degree of filling is restored to normal. When the speed of the primary element increases, the pressure in the working compartment increases thus tending to decrease the filling; this is however opposed by the increased speed of the pump F generating an increased pressure in the chamber e<1> so that the degree of filling remains constant. The spring D<1> merely counterbalances the weight of the diaphragm, valve and rod. Alternatively the spring may be of greater strength so that the valve is not moved until a predetermined speed of the primary element is reached, whereby delayed closing of the outlet valve is obtained; with this arrangement the degree of filling is not maintained constant. In a modified form, Fig. 2, the pump F which may be a gear or centrifugal pump, is associated with a reversing valve mechanism N comprising four non-return valves so arranged that the ports, n, n<1> are always delivery and suction respectively, irrespective of the direction of rotation of the pump, the hydraulic apparatus being of the kind in which the primary element can rotate in either direction. The delivery port e<2> communicates through duct e<5> and port e3 with the chamber e<1> communicating with the inlet port g of the valve G adjustable by hand wheel G<1>, the outlet port g<1> of the valve communicating with the chamber e<2> which in turn communicates through ducts e<6>, h, strainer H and duct h<1> with suction port n<1>; an expansion vessel L is provided. A relief valve K is provided in association with the valve G, or separate therefrom, or in association with the reversing valve N; the pump is driven by suitable mechanism from the primary shaft of the apparatus. The arrangement described above is applicable to a hydraulic brake, dynamometer or clutch. Instead of a separate pump, the primary rotor of the apparatus may itself control the pressure on the two sides of the diaphragm as in Fig. 10 wherein the primary rotor T carries, in addition to the cups, t, additional vanes t<1> generating a pressure which is communicated to one side of the diaphragm by a tangentially directed tube V, the other side of the diaphragm being connected to a radially arranged tube V<1>. Further modifications are referred to in the Provisional Specification. Specifications 24949 /10 and 243,888, [both in Class 106 (ii)], arc referred to.