GB606890A - Improvements in cooling devices for the lubricating oil of internal combustion engines - Google Patents

Abstract

606,890. Fluid-pressure servomotor-control systems. GARRETT CORPORATION. June 12, 1945, No. 14893. Convention date, Feb. 8, 1944. [Class 135] [Also in Group XIII] Control mechanism for an oil cooler 10 for internal-combustion engines having a heat transfer core 11 and a byepass muff 14, comprises a valve 40 which when closed prevents flow of oil through the byepass and which is subject to fluid pressure tending to open it, and when the oil is within a normal temperature range, to a balancing fluid pressure tending to close it, this balancing pressure together with a spring 54 holding the valve closed. When the oil is cold, temperature-responsive means reduce the balancing fluid pressure, and the fluid pressure tending to open the valve can then overcome the force of the spring 54. Oil from the engine enters chamber 23 and flows through port 24 to passageway 19 leading to muff 14. If the cooling apparatus becomes blocked, pressure builds up in chamber 23 and lifts valve 29 from its seat 30, at the same time closing opening 24 by valve 27. Oil is thus directed to passage 25 and byepaaaes the cooler apparatus completely; reverse flow from passage 25 into the cooler being prevented by valve 36 seating in port 34. Normally, spring 32 holds valve 29 closed and valve 27 open. Oil reaching the bottom of muff 14 from chamber 23 may in normal working enter the cooler by opening 15 and leave by opening 16 and passageway 21, or when the oil is cold may circulate round the muff and leave by passageway 20, and port 39. Port 39 is controlled by valve 40. This valve has a hollow stem 42 and an opening 43 controlled by a non-return ball valve 43a. At its far end valve 40 carries a piston 44 which slides in a cap 45. A spring 54 in the cap urges valve 40 in the closing direction. In normal operation, valve 40 is closed, the fluid pressure tending to open it being balanced by fluid pressure built up in chamber 46 by oil seeping through hole 43, and spring 54 keeping the valve closed. Oil then passes through the cooler out through passage 21 and passage 25 back to the engine. When starting up or when cooling causes the oil in the cooler partially to congeal, cold oil acts on a bi-metallic thermostatic coil 58 and causes it to rotate a sleeve 56 until a slot 57 co-operates with a port 55 in the stem 42. Port 55 is larger than hole 43 and oil drains through it from chamber 46 quicker than it enters, thus relieving fluid pressure in the chamber 46 and allowing fluid pressure in chamber 57 to open valve 40 against spring pressure 54. Oil then flows through byepass muff 14 instead of the cooler until its temperature again comes within the normal operating range. A sudden surge of pressure against valve 40 will open it even though port 55 be covered and chamber 46 filled with fluid, since piston 44 has openings 48 connecting chamber 46 with a recess 49, against which a valve 51 is pressed by a spring 52. The valve 40 opens by compressing spring 52 and opening valve 51 to permit escape of oil from chamber 46. In Fig. 8, a modified form of valve is shown. The hollow stem 60 extends through the piston 62 which is normally held against a stop 63. Movement of the piston relatively to the stem in the opposite direction is prevented by a snap ring 65. A spring 66 holds the piston against this snap ring. A thermostatic helix 71 surrounds the hollow stem 60 and rotates a sleeve 72 with cam edge 73 to cover or recover the port 70 in the stem 60. The valve is opened by a surge of pressure by yielding of the spring 66 and movement of the stem 60 within the piston 62, oil escaping from the chamber 46 through port 62<SP>1</SP>. The small hole in the face of valve 40 is protected by a screen.