Engine protective system
United States Patent [191 Goodwin Apr. 15, 1975 ENGINE PROTECTIVE SYSTEM [75] Inventor: Joe E. Goodwin, Conroe, Tex.  
 [73] Assignee: Sentinel Distributors, Inc., Denver,  
 [22] Filed: May 11, 1973 211 App]. No.: 359,598  
 Primary ExaminerCharles J. Myhre Assistant Examiner--R. H. Lanaus Attorney, Agent, or FirmCameron, Kerkam, Sutton, Stowell &amp; Stowell {57] ABSTRACT A system for protecting an internal combustion engine from damage in the event of a malfunction in the engine cooling system includes a coolant flow pressure controlled valve interposed in the oil line leading from an oil pressure actuated fuel control device back to the engine sump. When the engine is operating, the valve is normally maintained closed by the flow pressure in the cooling system. However, when the coolant flow pressure drops below a predetermined value due to a malfunction such as a break in a radiator hose, a leak in some other element of the cooling system, a faulty water pump or a slipping or broken fan belt, the valve is automatically opened by spring pressure to release the oil pressure at the valve and permit the oil to flow into the dump line to the sump. The resulting drop in oil pressure at the fuel control device enables the device to shut off the supply of fuel to the engine. The coolant flow pressure controlled valve is connected into the oil line in parallel with another normally closed temperature responsive valve which is opened when the temperature of the coolant rises above aa predetermined value.  
 4 Claims, 3 Drawing Figures ENGINE PROTECTIVE SYSTEM This invention relates to engine protective systems for shutting down internal combustion engines in response to abnormal pressure or temperature conditions existing in the lubricating or cooling systems of such engines. and is particularly directed to an improvement of engine protective systems of the type shown and described in US. Pat. Nos. 3.202.143 and 3.385.278.  
  1n the systems disclosed in US. Pat. Nos. 3.202.143 and 3.385.278 there are provided both an oil pressure controlled engine shut-down device. referred to hereinafter as an Oil Sentinel. which automatically cuts off the supply of fuel to the engine whenever the pressure of the oil in the lubricating system falls below a predetermined value. and a coolant temperature controlled shut-down device. hereinafter referred to as a Heat Sentinel. which functions to actuate the Oil Sentinel and cut off the fuel supply whenever the temperature of the coolant exceeds a predetermined maximum. In accordance with the present invention. the prior systems of the above-mentioned patents are improved by the addition of a third safety device. hereinafter referred to as a Coolant Flow Pressure Sentinel. which functions to actuate the Oil Sentinel and cut off the fuel supply whenever the flow pressure of the coolant falls below a predetermined minimum due to a malfunction in the engine cooling system.  
  In general. the improvement provided by the present invention resides in the addition to systems of the character shown in US. Pat. Nos. 3.202.143 and 3.385.278. embodying an Oil Sentinel and .1 Heat Sentinel. of a Coolant Flow Pressure Sentinel in the form of a valve which is connected into the oil dump line leading from the Oil Sentinel back to the engine sump. in parallel with the Heat Sentinel. which valve is normally maintained in closed position by the flow pressure existing in the cooling system. If the coolant pressure drops below a predetermined value due to. for example. a break in a radiator hose. a leak in some other element of the cooling system. a faulty water pump or a slipping or broken fan belt. a suitably calibrated spring opens the valve and permits the oil to flow through the dump line to the sump. This release of the oil pressure at the inlet of the valve in turn reduces the oil pressure within the Oil Sentinel and causes the latter to close off the supply of fuel to the engine.  
  Referring now to the drawings. wherein like reference characters indicate like parts throughout the several views;  
  FIG. I is a diagrammatic side elevational view of an internal combustion engine fitted with the improved protective system of the present invention.  
  FIG. 2 is a schematic diagram of the essential elements of the system shown in FIG. 1; and  
  FIG. 3 is a vertical cross-sectional view of the coolant flow pressure controlled valve. or Coolant Flow Pressure Sentinel. diagrammatically illustrated in FIGS. 1 and 2, showing the valve in normally closed position.  
  The engine protective system illustrated in FIG. 1 comprises an oil pressure controlled engine shut-down device or Oil Sentinel A. a coolant temperature controlled shut-down device or Heat Sentinel B. and a coolant flow pressure controlled valve or Coolant Flow Pressure Sentinel C. in combination with a typical internal combustion engine or prime mover D having the usual carburetor E. fuel pump F. oil pump G. cooling jacket H. radiator l and fan J.  
  Since the detailed construction and method of operation of the Oil Sentinel A and Heat Sentinel B are fully disclosed in the above-mentioned US. Pat. No. 3.202.143. the details of these devices will not be described herein. However. it should be noted that the Oil Sentinel A can be connected to the intake or pressure side of the fuel pump F and is mandatorily connected to the pressure side ofthe oil pump G. Heat Sentinel B is simply threaded into a tapped opening in the jacket H. and has an oil inlet fitting connected by a pressure oil supply conduit 12 to the oil outlet fitting I4 of Oil Sentinel A. and an oil outlet fitting I6 connected by a non-pressure oil return conduit 18 leading to the sump 20 in the engine block.  
  Oil Sentinel A has an oil inlet fitting 22 which is connected by an oil supply conduit 24 to the oil pump G of the lubricating system of the engine with which it is associated. and includes an internal fuel valve interposed in the fuel line 26 of the engine which is maintained in an open position. permitting a free flow of fuel from the fuel inlet fitting 28. through the valve to the carburetor E. as long as the oil pressure in the lubricating system of the engine is maintained at or above the predetermined value established for operation of the Oil Sentinel A. However. when the oil pressure drops below said predetermined value. the fuel valve closes to shut off the flow of fuel to the engine. As described in US. Pat. No. 3.202.143. the Oil Sentinel A may also have its fuel valve partially opened by a manual control K when the operating oil pressure is insufficient to actuate the fuel valve to its full open position.  
  The Heat Sentinel B includes an internal valve interposed between the oil inlet 10 and the oil outlet 16 which is normally maintained closed by a suitably calibrated spring so as to prevent the flow of oil into the dump conduit 18. Also included is a fusion type thermal sensing element responsive to temperature variations in the coolant medium in the cooling jacket H which opens the valve. and thereby causes a drop in the oil pressure to which Oil Sentinel A is subject. sufficient to effect closing of the fuel valve. whenever the temperature of the coolant exceeds a predetermined value.  
  The foregoing description applies primarily to an engine safety shut-down system of the type disclosed in US. Pat. No. 3.202.143. the details of which are incorporated herein by reference. The present invention adds to this known system. in parallel with the Heat Sentinel B. a Coolant Flow Pressure Sentinel C adapted to be actuated in response to a drop in flow pressure in the cooling system so as to cause a drop in the oil pressure to which Oil Sentinel A is subject. sufficient to effect closure of the fuel valve. upon any malfunction in the cooling system.  
  As shown in FIG. 3, Coolant Flow Pressure Sentinel C comprises a two-part valve housing 30 having a lower part 32 wherein are formed an oil inlet 36. an oil outlet 38. a valve seat surrounding the upper end of the vertically extending portion 42 of inlet 36. and a plurality of downwardly extending passages 44 connecting the space within housing part 32 above the valve seat 40 with the horizontally extending oil outlet 38. The upper part 34 of housing 30 has a vertically extending bore 46 in which are housed a disc valve assembly 48. preferably made of a suitable plastic material. and a spring which yieldably urges the valve assembly 48 upwardly toward the horizontally extending portion of the body part 34 forming the upper end of bore 46. The two body parts are detachably connected to one another by screw threads 52, and a gasket 54 is interposed between the two parts so as to make the space within the body oiltight. The upper portion of disc valve assembly 48 is fluted as indicated at 56. and houses a compression spring 58 which abuts the upper end of a Buna rubber disc valve 60 which. when the Coolant Flow Pressure Sentinel C is in normal operation. as shown in solid lines in H6. 3. engages the valve seat and prevents the flow of oil from inlet 36 to outlet 38.  
  Fixed to the upper end of the upper part 34 of valve housing 30 is a diaphragm valve operator assembly 62 comprising a diaphragm 64, a backup plate 66 fixed to the bottom surface of the diaphragm a valve operator 68 in a form of a plunger fixed to and extending verti cally downwardly from back-up plate 66 into engagement with the top of disc valve assembly 48., upper and lower diaphragm housing plates 70 and 72, the peripheries of which overlap and clinch therebetween the pe riphery of the diaphragm. and an internally threaded nipple member 74 fixed to the upper diaphragm housing plate 70 and opening downwardly into the space above the diaphragm.  
  As indicated in H65. 1 and 2. Coolant Flow Pressure Sentinel C is connected across the pressure oil supply conduit 12 and the non-pressure oil return conduit 18 in parallel with the Heat Sentinel B; that is, the oil inlet 36 of valve housing 30 is connected to conduit 12 by a branch conduit 12&#39;. while the oil outlet 38 of the valve housing is connected to conduit 18 by a branch conduit 18&#39;. Furthermore. the nipple member 74 of the Coolant Flow Pressure Sentinel C is connected by a coolant conduit 76 to a hose 78 on the pressure side of the coolant pump (not shown) leading to the bottom of the radiator l. or to any other suitable part of the coolant circulating system. With this arrangement the flow pressure of the coolant is applied to the upper surface of diaphragm 64 and, through valve operator 68, to the disc valve assemly 48 so as to force the latter downwardly against the force of spring and. as long as the coolant flow pressure exceeds a predetermined value. to hold the disc valve 60 in engagement with valve seat 40. thus preventing the flow of oil through the valve housing from conduit 12 to conduit 18&#39; and thence into the sump 20. The compression spring 50 serves to absorb any overtravel of the disc valve assembly after the Buna rubber disc valve 60 has come into engagement with the valve set 40.  
  Should the flow pressure of the coolant in conduit 76 as applied to the diaphragm 64 fall below the predetermined minimum due to a malfunction in the cooling system, for example, in the event that the belt driving fan J should break or slip. spring 50 will move the disc valve assembly 48 upwardly. off valve seat 40, as indicated in broken lines in FlG. 3, and permit the free flow of oil through the valve housing 30 from conduit 12&#39; to conduit 18&#39;. and thereby reduce the oil pressure within Oil Sentinel A so as to effect closure of the fuel valve therein and stoppage of the engine. in the manner described in the above-mentioned US. Pat. NO. 3,202,143.  
  ln view of the fact that practically all gasoline and diesel engines produce at least 1.5 to 4.0 psi coolant flow pressure during engine starting and at idling speeds. the elements of Coolant Flow Pressure Sentinel C are so designed that the coolant pressure must drop below l.5 psi before the device is operative to shut off the supply of fuel to the engine in order to avoid false shut-downs.  
  Although only one specific embodiment of the invention has been illustrated and described herein. it will be apparent to those skilled in the art that various changes may be made in the details of construction of the Coolant Pressure Sentinel without departing from the inventive concept.  
 What is claimed is:  
  I. In apparatus for controlling the flow of fuel to an internal combustion engine in response to pressure and temperature conditions existing in the pressure lubricating system and the cooling system of the engine of the type comprising a valve in the fuel supply line of the engine. pressure actuated means normally subject to the pressure of the oil in said lubricating system for maintaining said valve in open position as long as the pressure exerted on said means is at least equal to a predetermined value means operable to close said valve when the pressure exerted on said pressure actuated means drops below said predetermined value. and means responsive to the temperature of the coolant in said cooling system for reducing the pressure on said pressure actuated means below said predetermined value when said temperature rises above a predetermined temperature, the improvement which comprises:  
 the inclusion in said apparatus of means responsive to the flow pressure of the coolant in said cooling system for reducing the pressure on said pressure actuated means below said predetermined value when the flow pressure of the coolant drops below a predetermined pressure even though the temperature of the coolant remains below said predetermined temperature. the coolant flow pressure responsive means comprising a valve housing having an inlet connected to the pressure side of the lubricating system and an outlet connected to the nonpressure side of said system. a valve in said body controlling the flow of oil between said inlet and outlet, means subject to the flow pressure of the coolant in the cooling system for maintaining said valve in closed position when said coolant flow pressure is at least equal to a predetermined pressure, and yieldable means for opening said valve when the coolant flow pressure drops below said predetermined pressure.  
  2. Apparatus as defined in claim 1 wherein the coolant flow pressure responsive means is connected to the pressure side and the non-pressure side of the lubricat ing system in parallel with the temperature responsive means.  
  3. Apparatus as claimed in claim I wherein said coolant flow pressure responsive means includes a diaphragm in said valve housing, means for subjecting one side of said diaphragm to the flow pressure of the coolant in the cooling system. a plunger having one end thereof in engagement with the other side of said diaphragm and the other end in abutment with said valve. said plunger urging said valve into closed position when the pressure exerted on said diaphragm is at least equal to said predetermined pressure, and yieldable means urging said valve toward open position.  
  4. Apparatus as defined in claim I wherein said pres sure actuated means has an oil inlet connected to the pressure side of the lubricating system and an oil outlet. and said temperature responsive means has an oil inlet,  
 an oil outlet. a normally closed valve controlling the flow of oil between said inlet and said outlet. and a thermal responsive element operative to open said valve when the temperature of the coolant rises above said predetermined temperature. and which includes conduit means connecting the oil inlet of said temperature responsive means to the oil outlet of said pressure actuated means. and conduit means connecting the. oil outlet of said temperature responsive means to the nonpressure side of the lubricating system. said coolant flow pressure responsive means having an oil inlet and an oil outlet. conduit means connecting the oil inlet and outlet of said coolant flow pressure responsive means LII to the oil outlet of said pressure actuated means and the low-pressure side of the lubricating system. respectively. in parallel with the oil inlet and outlet of said temperature responsive means. a valve controlling the flow of oil between the oil inlet and outlet of said coolant flow pressure responsive means. means for subjecting said last-named valve to the flow pressure of the coolant in the cooling system and maintaining said valve in closed position as long as the coolant flow pressure is at least equal to a predetermined pressure. and means for opening said valve when the coolant flow pressure drops below said predetermined pressure.