Patent GB-624097-A (GB)
Title: Improvements in or relating to apparatus for limiting fluid loss from a fluid system
IPC: F16N29/00
Filed: 1946-08-19
Abstract: 624,097. Fluid-pressure servomotor-control systems. BOOTH, H. T. Aug. 19, 1946, No. 24695. Convention date, Aug. 27, 1945. [Class 135] [Also in Group XXXIV] Apparatus for shutting off the flow in a part of a fluid system on loss of fluid therefrom includes two flow meters situated at the inlet and outlet of that part of the system and each having an element whose movement is proportional to the flow at that point, a valve for shutting off flow through the system, and means to shut or open the valve according as the rate of flow at the outlet meter is less than or equal to that at the inlet meter. The invention is applied to the lubricating system of an internal-combustion engine in which, under normal conditions, a pump 15, Fig. 1, draws oil from a reservoir 11 and delivers it to the engine, and a pump 16 delivers the used oil back to the reservoir via a cooler 17. If loss of oil occurs in the conduit between two flow responsive devices 18, 22, a valve 19 will be actuated to short-circuit the cooler and divert the oil straight back to the reservoir through a byepass line 21. Each flow responsive device comprises a spring-loaded mushroom valve, and the degree of opening of the valve is indicative of the flow past it. After taking up a small amount of lost motion, the stem of each valve depresses a bellows 23 forming one end of a hydraulic link, the other end of each link terminating in a further bellows 25, both of which act on a floating lever 31 so that the lever is actuated by the differential flow past the two flow detectors. Normally, the flow past the two detectors will be equal and the lever 31 will be moved bodily upwards during which movement a slot in a vertical arm 32 connected to the lever will slide past a fixed stud 34 engaged in a slot in the arm 32. When oil is lost, due to damage to the conduit between the two flow detectors, the response of detector 22 will be lessened and lever 31 and arm 32 will be tilted in a clockwise direction about the stud 34 to close an electric switch 35 and energize a solenoid 39. The latter closes a piston valve which cuts off the supply of high pressure oil from detector 18- to the underside of a piston 42 carried by valve 19 so that the latter will be actuated to shut off the supply of oil to the cooler and divert it through line 21. Valve 19 is situated in a unit including flow detector 18 and solenoid 39, and a second unit comprises flow detector 22, lever 31, and switch 35. When flow is first started in the system, oil passing valve 18, Fig. 7, is led by a connection (not shown), to the underside of piston 42 and lifts the latter so that a projection 78 on its stem engages and lifts a valve 43 to allow oil to flow to the cooler through port 58. When pressure oil is cut off from the underside of piston 42, the lowering of the latter will force valve 43 to the closed position and the inflowing pressure oil will force open the spring-loaded composite valve 62 ... 64 and will flow to the byepass line through port 61. This oil also assists spring 71 to load the upper surface of piston 42 to which it has access through grooves 80. The oil underneath the piston can flow away through aperture 92.