US 3577726 A
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United States Patent 1 13,577,726
 Inventor Harold H. Wagner  References Cited Peoria, UNITED STATES PATENTS  P 1,138,628 5/1915 Cook 123/142  My 1 835 299 12/1931 Greuter 123/142 Patented May 4,1971  Assi ee Cater mar Tractor Co 2,511,348 6/ 1950 K1ttler 60/13 P m 3,052,085 9/1962 Tauschek 60/13 "5" 3,077,189 2/1963 Eamshaw 123/65 3,464,202 9/1969 Wagner 60/ 13 1 Primary Examiner-Douglas Hart  FUEL SYSTEM FOR NATURAL GAS AttorneyFryer, Tjensvold, Feix, Phillips and Lempio TURBOCHARGED ENGINE p 5 Chums l Drawmg ABSTRACT: A turbocharged natural gas engine adapted for  US. Cl 60/13, use with very low pressure gas by virtue of introducing the gas 123/ 1 19, 123/120, 123/ 142 and combining it with air to provide a combustible mixture up-  lnt.Cl. ..F02b 37/00, stream of or on the low pressure side of the turbocharger. F02m 21/04 Safety means are provided to insure against damage by Field of Search 1 3, backfire and against admission of explosive gases to the engine 39.11; 123/142, 119 (C), 120 crankcase.
AFTERCOOLER TD CRANKCASE PATENTED HAY 4 l9?! M2235 EAL INVENTOR HAROLD H. WAGNER Mfg- ATTORNEYS v BY WW FUEL SYSTEM FOR NATURAL GAS TURBOCHARGED ENGINE Natural gas is often available as a low cost engine fuel, but in many cases, the source is of low pressure gas which presents a problem of introducing it into the high pressure air stream of a turbocharged engine. Compressors have been employed to solve this problem but they are costly to acquire and operate and tend to offset the advantage of the low cost fuel. Other problems arise from the use of gas as a fuel in connection with backfiring which occurs in a spark-ignited engine and also in connection with the accumulation of the highly combustible mixture in the engine crankcase.
The present invention overcomes the problems recited above as well as others and will best be understood from the following specification which makes reference to the accompanying drawing.
The drawing is a schematic view with parts in section of mechanism employed in carrying the system of the present invention into practice. 7
in the drawing a conventional-air cleaner is shown at 10 and air flowing from the cleaner is directed through a conduit 12 to the compression section 14 of a turbocharger. A carburetor generally indicated at 16 mixes air and natural gas, the latter entering through a pipe 18. The carburetor will not be described in detail as it is one of several such devices manufactured forthe purpose of combining air and gas and maintaining a proper fuel-air ratio.
The air and gas so combined are directed to the turbocharger and thence through an aftercooler 20, which is also of conventional design, to a backfire relief device generally indicated at 22. A passage 24 of this device communicates with an intake manifold 26 of an engine which is not shown. A butterfly valve 34 in the passage controls the volume of combustible mixture to the engine and is adjusted as by a governor (not shown) or other simple means with which it is connected by linkeage, a part of which is shown at 30.
The present invention incorporates two safety devices, one of which is the backfire relief device. This device has a cover 28 held in place by springs 30, the preload upon which is such that the cover will not be raised by normal engine operating pressures, but will be lifted against the force of the springs to relieve greater pressures experienced upon engine backfire. This relief device includes a metal screen 32 through which the backfire flame would have to pass in order to travel into the vicinity of the combustible mixture being delivered to the engine.
The screen operates in this manner because the heat of the backfire is so dissipated by the large surface area of the screen that ignition of the combustible mixture would not occur to cause damage to parts upstream of the backfire relief device.
Another advantage of the present system is that it prevents accumulation of the combustible mixture in the engine crankcase. The compressor includes lubricated bearings and excess lubricant is caught in a well 36in its housing and conveyed through a conduit 38 to a gas liquid separator generally indicated at 40. The separator comprises a closed container with screens 42 separating it into upper and lower sections. it has an outlet through a conduit 44 which communicates with the intake conduit 12 and gas passing upwardly through the screens 42 deposits oil entrained therewith on the screens from which the oil gravitates to a collection sump in the body of the housing. When the oil level reaches an outlet pipe 46 which communicates with a stand pipe 48, it flows by gravity to the engine crankcase. The stand pipe 48 is vented to atmosphere at its upper end to permit oil to freely enter its lower end. Thus, gaseous fuel which may enter the chamber 36 of the turbocharger through bearings which support the blower shaft passes with the oil to the gas separator 40 and is returned into the fuel stream without danger of entering the crankcase where its ignition could be extremely dangerous.
1. in a fuel system for a natural gas turbocharged engine; a turbocharger, conduit means directing air to the turbocharger from the upstream side thereof, in the direction of fluid flow through said turbocharger, means for admitting gas into sard conduit means to provide a combustible fuel mixture upstream of said turbocharger, an intake manifold for said turbocharged engine, passage means connecting said turbocharger and said intake manifold, and a backfire pressure relief device located in said passage means between said turbocharger and said intake manifold to effectively isolate said turbocharger from the harmful efiects of backfiring in said intake manifold.
2. The invention of claim 1 in which the backfire pressure relief device has a wire screen to dissipate heat from backfire gas positioned to prevent flame from moving upstream in the direction of fluid flow through the fuel system.
3. The invention of claim 1 wherein the backfire pressure relief device includes a chamber defined by walls and a cover member which directly separates the interior of said chamber from the ambient and is yieldingly urged to close off said chamber from said ambient.
4. In a fuel system for turbocharged natural gas engine; a turbocharger, conduit means directing air to the turbocharger from the upstream side thereof in the direction of flow through said turbocharger, means for admitting gas into said conduit means to provide a combustible fuel mixture upstream of said turbocharger, a crankcase for said turbocharged engine, a conduit connected between said turbocharger and said crankcase through which turbocharger lubricating oil is drained to said crankcase, and a gas-oil separator to separate any combustible fuel mixture which may pass with said lubricating oil through said conduit.
5. The invention of claim 4 with means for directing the separated fuel mixture back into the system upstream of the turbocharger.