US2947291A

US2947291A - Compression ignition engine

Info

Publication number: US2947291A
Application number: US718029A
Authority: US
Inventors: Earl R Klinge
Original assignee: Continental Motors Corp
Current assignee: Continental Motors Corp
Priority date: 1958-02-27
Filing date: 1958-02-27
Publication date: 1960-08-02
Anticipated expiration: 1977-08-02

Description

2 Sheets-Sheet 1 I TO ENGINE LUB. SYSTEM E. R. KLINGE COMPRESSION IGNITION ENGINE FIG.I.

INVENTOR. EARL R.KLINGE BY M 1 ATTORNE FIG.3.

0.2(25-50 p s.i.)

ono DUE 10 A.F|XED RETRACTION VALVE REGION OF LUB. on. ADDITION CONSTANT FULL LOAD 0o 00 IO 20 CONSTANT IOOORPM PEP. STROKE REGION OF LUB.

OIL ADDITION FUEL QUANTITY FUEL 1960 E. R. KLINGE 2,947,291

COMPRESSION IGNITION ENGINE Filed Feb. 27, 1958 2 Sheets-Sheet 2 OUTLET TO NOZZLE INVENTOR.

EARL R.KL|NGE delay duringselected ranges of operati 2,947,291 s COMPRESSION IGNITION ENGINE Earl R. Klinge, Detroit, Mich., as signor to Continental invention relates to. compression ignition engi nes "and more particularlyto -a ineans for adding ignition accelerator to the fuel .deliverysystem .during periods b 10w load and low' s'peed operation toreduce ignition delayland consequentroughnesslof thefengine. v V 1 The present invention is particularly adaptable to compression 'ignition engines. using. gasoline. or otherilow, 1;;-

ignition quality fuels rather thanconventional diesel oil fuels. Suchhigher octane fuels havecomparatively 1 w. o'etane; "numbers; that -is,..their ignition quality; is not as. high a'sdieseloils for use in eompression-ignition nginesg .ll-Ii'gli speed-, diesel engines with compressionLratios up; to; outgQItol maybe designed such that. ignition delay H the instant of fuel injection is notgreat enoughQ during norrnaloperation to cause the roughness generally characteristic f compression ignition engines. 3 However, at lower speeds andloads, ignition delay increases due to cooling 01f of the combustion chamber-and'the engine loses in efficiency and smooth operation'.' This can be overcome by increasing the octane number ofthe. fuel through the addition of anignition accelerator but then the purpose of using gasoline or like fuelsis,v deeat d- 2 Q An object of the present invention is to improve per forman'ce of compression ignition engines operated gen fuels of..-low cetane number by providing a meansj'for adding ignition accelerator to theffuel' supply system at pre'determinedj ranges of enginefoperationi Another object of the invention islto" decrease ignition ofje'ompression ignition engines by providing means for a'ddingignitionj selected ranges of operation. v a

A further object of the invention is to' irnprove operating' characteristics of compression ignitionengines using fu els of low cetane numberjby adding engine lubricating oil tothe fuel supply system during selected ranges r 1'1" engine operation. v

Still another object ofthe presentinvention is to. improve compressionignition engine operation byeonsti'ucting a fuel injectionlpump having aivalve connecting the. deliveryside of the pump with a source of ignition accelerator supply andjoperable to admit ignition acceleratonl to the fuel being delivered to the engine at "selected .dper ating ranges. l s s ,A still furtherobject of the invention. is-to provide.

Uni d at s. ete? particularchanges in'fuel pressures at selected engine" speeds. t t I ,Xet. a. furtherfobject of the invention is to provide a means for adding ignition accelerator to a compres sion ignition engine by constructing a valveconnected between the downstream side of a variable pressure fuel: injection pump and a pressurized ignition accelerator supply and operable to open upon a decrease of residual fuel pressure to below the ignition accelerator pressure, For a more complete understanding of the invention,.

out the several views and in which Fig. 1 is aschematic drawing illustrating a preferred system embodying theinvention.

IFigc 2 is a cross-sectionalyiew of a preferred fuel' injection pump constructed to :utilize a. preferred method ofadding ignition. accelerator to the fuel supply system. of. a compression ignition engine. h h Fig.3 is a chart illustrating a preferred fuel pressure: relationship for utilization in operating the present preferred system.-

engines using gas'olineor like fuels that makes the pres-.

Fig. 4 is a second chart illustrating a-second pressure. relationship observable in the preferred system afore: 1 said, and.

Fig. 5-is a cross-sectional view taken substantially on structi'on.v I 7 [Ike principalv characteristic of compression ignition theline 5-5 of Fig. 2 to illustrate a preferred valve conent-inventionfeasible and desirable is that at low speed engine.=operating ranges, and at low engine loads, ignition delay becomes too great for' efficient and smooth operation. The chief concept of the present invention is to" make use of fuel supply system pressures, which accelerator to the fuel supply system only during these an improved means of adding ignition accelerator to the fuel supply system of a compression ignition engineby constructing a valve connected between a sourceof ignition-accelerator supply andthe fuelsupply system and operable to open inresponse to a decrease in engine. P

varyrwith enginespe'ed and load, for. operating a valve and the fuel supply system.

connected between a source of ignition accelerator supply.

@The'most available sourceofignition' accelerator in gasolineffueled compression ignition engine is the engine: lubricatings'ystem. Obviously meansjcould' be provided for'adding'a continuous small flow of ,oil. to the fuel{ supply, but this woulddefeattheipurpose of using. a gasolinefconsuniing engine and require an excessively large supply of oil. A preferred system embodying the.

present invention 'is'ilhlstr ated'in the present drawings, Fig; 1 illustrating a compression ignition engine 10 having a fuel supply source or tank 11 and a lubricating oil supply source or tank 12, A fuel pump 13 pumps fuel under relatively low pressure, which preferably is constant, toa fuel injection pump 14 operable to pump fuelintermittently. under high pressure to-a fuel injector nozZleQ ISofconventional construction and operable to open under afuel pressure preferably as indicatedby the line .V.O.P. (valve opening pressure) in the charts.

Figs. and 4, the pressure denoted for purposes of discussion being'in'the neighborhood of about 2500 psi.

A lubricating oil pump 16 is operableto pump oil fromitheoil tank 12 to the engine 10, prefer-ably under a pressure ofabout 25 to 50 p.s.i. for purposes of discussion', as indicated by the jdottedline. O.P. (oil pressure) in thecharts." I

A valve '1 7 is preferably connected. intermediate the doiwnstreamf side of the oil pump 16 and the downstream side of the fuel injection pump ;14, the valve -17 pref-' 'erably being'a'simplified check valve, pressure respon sive' to open only when fuel j delivery pressure' drops below oil system pressure.

".'I .h'e' preferred substantially conventional fuel"V inje ction pump'l t is illustrated in.lmoredetailfin. Fig.1},- as; comprising a housing 20 provided with a fuel inlet'zl,

fuel pressure outlets 24, a pumping piston 25, a control chamber 26, a distributing chamber 27, and a pump chamber 28. v

- The piston 25 is operable to reciprocate up and down, being actuated by a cam 30 mounted on a shaft 31 rotated through a gear 32- connected preferably-in any conventional measure to the engine. On thejupward stroke of the piston 25, fuelin the pump chamber 28 is put under pressure after the piston closes off a fuel inlet port 33 and a fuel outlet port 34 respectively connected with the inlet 21 and return outlet 22. A spill passage 35 extends through the piston 25 from the pump chamber 28 to the control chamber 26, being opened when the piston 25 has moved a distance sufiicient to permit a spill port 36 to clear aycontrol valve sleeve 37 disposed in the control chamber 26, thus relieving pressure in thepump chamber 28, the control chamber 26 being connected through passages 38 and 39 respecoperates to open a conventional retraction type discharge. check valve 46 against the pressure of a return spring 47, the. fuel passing through a passage 48 in the retraction valve to an annular groove 49 and then passing into the fuel pressure chamber 23 when the upper piston 50 of the valve 46 clears the upper end of a valve cylinder 51. The fuel under pressure then passes through a port 52 into a delivery chamber 53; The fuel then flows out a passage 55 to the annular distributing chamber 27 adjacent the pump piston 25.

In pumps of the present type, called single piston pumps as differentiated from multiple piston pumps, the fuel is distributed to a plurality of fuel pressure outlets 24, only one of whichis here illustrated in detail. The piston 25 is made torotate by any desired means (not shown), and is provided with a grooveor flute 60 which is openly connectedwith the annular distributing chamber and alternatelyopenly connected with ports 61 (only one shown herein), each of which communicates by a passage '62 with respective fuel outlets 24, which are connected in turn to the fuel injector nozzles 15, only one of which is shown in Fig. 1.

The nozzle 15 is preferably of the conventional type having a fixed nozzle orifice area. Thus, with a constant volume of fuel being pumped intermittently into the delivery system during engine operation, intermittent fuel pressure in the line to the nozzle 15 will rise to a higher peak than the nozzle valve opening pressure, as indicated. by the upper ascending 1ine-AA in Fig. 3, so that on each stroke, the nozzle operates to inject fuel into the. engine combustion chamber (not shown). Since the time during which this constant volume of. fuel ispumped into the line decreases as the engine r.p.m. increases, the peak line pressure will rise to correspondingly higher values above valve opening pressure-as engine rpm. increases, due to the fixed nozzle orifice area of the nozzle 15. I

As soon as fuel pressure is relieved from the pump chamber 28, representing the eifective end of the piston stroke, the return spring 47 moves the retraction valve 46 downward. The retraction valve 46 is so constructed that the piston 50 engages the upper end of the valve cylinder 51, closing communication between the pump chamber 28 and the pressure chamber-23, prior to seating of the valve 46. Thus the volume of thedelivery Any suitable control system between the retraction valve 46 and the injector nozzle 15 is increased by a predetermined increment, causing line pressure in that portion of the system to decrease immediately, proportionately with the increase in volume. This is a conventional manner of preventing after-dripping from the injector nozzle, the degree of retraction valve motionafter fuel cut-01f being selected to always reduce line pressure below nozzle valve opening pressure, so that the injector nozzle will close immediately after injection, andthe residual pressure remaining in the line after such line-unloading is indicated by the lower solid ascending line B-B in Fig. 3. This residual pressure will be in substantially direct ascending relationship with increasing fuel delivery pressure, due to the substantially uniform line-pressure drop.

The position of the sleeve 37 in the control chamber 26 is regulated relative to engine loads. Thus, at lower loads, the sleeve 37 is positioned lower in the control chamber 26 to relieve pressure after a relatively short piston stroke, so that the delivered fuel quantity per stroke is smaller, and since this volume is pumped through a fix'ed'areanozzle orifice, the maximum or peak line pressure is relatively low. At higher engine loads, the sleeve 37 is positioned higher in the control chamber 26 to relieve pressure after a relatively longer piston stroke, so that the delivered fuel quantity per stroke is larger, and again being pumped through the same fixed area nozzle orifice, the maximum or peak line pressure is rela tively higher. If the volume of fuel is pumped into the line over a long enough timeperiod, line pressure would reach an equilibrium dependent upon the size of the nozzle orifice and the volume of fuel delivered, but since pressure is relieved before equilibrium pressure is reached, the peak line pressure at different volumes in the present system will be characterized by the upper ascending curve A'--A of Fig. 4. Pressure drop due to the operation of the fixed retraction valve 46 as previously described will produce a residual pressure curve such as in Fig. 4. An oil inlet 63 is provided in the pump housing 20 and is normally closed by the check valve 17 by the pressure of fuel in the delivery chamber 53. However, as is noted in the charts of Figs. 3 and 4, residual fuel pressure drops below the pressure of oil in the fuel sys-.

tem at certain lower engine speeds (Fig. 3), and lower loads (Fig. 4) such that the valve 17 opens and the oil will be injected into the fuel delivery system, raising thecetane number of the fuel and acting as an ignition accelerator iii the engine. combustion chamber according to well recognized-compression ignition engine principles. Obviously, oil pressure and residual pressure may be so controlled to provide for opening of the check valve 17 onlyat those low speeds and fuel loads at which ignition delay would cause rough and inetficient engine operation.

In the present case, selected for purposes of discussion, Fig. 3 illustrates an engine having fuel peak line delivery pressures above about 25000 p.s.i., variable as engine speed varies over a range of about 1000 to 3000 r.p.m., so that line pressure drop provides residual pressure of under about 2500 p.s.i., varying downward fromunder 2500 psi. to below 25 to 50 p.s.i.

Thus, in net etfect, ignition accelerator, in the present case being drawn from the engine lubricating system, is added to the fuel at selected ranges of low speed and low load engine operation.

Although I have described only one preferred embodiment of the invention, it will be apparent that various changes and'modifications therein may be made without departing from the spirit of the invention or the scope of the appended claims.

I -claim:

- p 1., In a fuel supply system for a compression ignition engine, means delivering said engine fuel under pressure variable relative to engine speed and load, a source of 2. In a fuel supply system for a compression ignition engine, means delivering to said engine'fueluuderpressure variable relative to engine speed and load, a source ofignitionacceleratorsupply, and a pressure responsive operating at relatively ,low load and lowspeed, whereby admission of lubricating oil into said delivery system actsto, decrease fuel ignition-delay. t y 46. --In'a fuel supply system'for a compression ignition engine, a fuel injector nozzle having a valve operable to openat ;a predeterminedfuel pressure, a fuel ignition pump connectedwith said nozzle and operable to vdeliver valve connectedintermediatesaid deliverymeans and Saidv ti n a e era or supp y and ac uate po decrease of fuel pressure to open and admit ignition accelerator into said fuel, said' delivery means comprising a fuel injection pump operable to intermittently pump fuel under pressure to said engine and having means retaining downstream of said pump between pressure strokes a residual fuel pressure variable relative to engine speed and load, said valve being connected withsaid delivery means downstream of said pump and operable to open only in response to decrease of residual fuel pressure to a predetermined value.

3. In a fuel supply system'for a compression ignition engine, means delivering to saidengine fuel under pressure variable relative to engine speed and load, a source of ignition accelerator supply, and a pressure responsive valve connected intermediate said delivery means and said ignition accelerator supply and actuated upon a decrease of fuel pressure to open and admit ignition accelerator into said fuel, said source of ignition accelerator supply comprising a lubricating oil system connected with said engine, means obtaining oil pressure in said lubricating oil system, said valvebeing'operable only in response to a difierential between fuel'pressure and oil pressure. a

4. In a fuel supply system for a compression ignition engine, means delivering to said engine fuel under :presfuel thereto intermittently at a pressure above said nozzle valve opening pressure and variable. relative to engine speed-and load, saidpump. having means increasing the volume of said supplyzsystemdownstream of said pump immediately following each pump pressure stroke to decrease fuelnpressure downstream of said pump, by "a uniform increment sufiicient to obtain a residual pressure below said nozzle valve opening pressure and variable relative to engine speed and load, a source of ignition accelerator supply and means maintaining same at a substantially fixed predetermined pressure below said nozzle valve opening pressure, a pressure responsive valve connected intermediate said ignition accelerator supply and said fuel supply system downstream of said pump, said pressure responsive valve being operable to open only when said residual fuel pressure falls below said ignition accelerator supply pressure to admit ignition accelerator form increment Sulfibienbtt) obtain a residual pressure sure variable relative to engine speed and load, a source of ignition accelerator supply, and apressure responsive valve connected intermediate said delivery meansjand I said ignition accelerator supply and actuated upon ade crease of fuel pressure to .open and admit ignition accelerator into said fuel, said source of ignition accelerator supply comprising a lubricating oil system connected with said engine and having an oil pump for pressurizing said I I I oil, said delivery means comprising a fuel injection pump operable to intermittently pump fuel under pressure to said engine and having means retaining downstream of said pump between pressure strokes a residual fuel pressure variable relative to engine speed and load, said valve being connected with said delivery means downstream of said pump and operable only in response toadiiferential between said residual fuel pressure and lubricating oil pressure.

5. 'In a fuel supply'system for acompr'ession ignition supply comprising a lubricating oil system connected with said engine and having an oil pump for pressurizings aid oil, said delivery means comprising a fuelinjection pump operable to intermittently pump fuel 'under'pressure to below said nozzle valve opening pressure and variable relative to engine speed and load, a lubricating oil system connected with said engine and means maintaining same at 'a substantially fixed predetermined pressure be- 1 low said nozzle valve opening pressure, a pressure responsive valve connected intermediate said oil system and said I fuel supply system downstream of said pump, said pressure responsive valve being operable to open only when said residual fuel pressure falls below said oil pressure to admit lubricating oil into said fuel supply system for accelerating engine ignition.

8. In a fuel supply system for a compression ignition engine having a lubricating oil system, a fuel injection chamber openly-connected with said'fuel outlet, means in {said casing intermittently pumping fuel under pressure said engine and having means retaining downstream of said pump between pressure strokes a residual fuel QPI'QS- sure variable relative to engine speed and load, said valve being connected with said delivery means downstream of said pump and operable only in response to a diner-f ential between said residual fuel pressure and lubricating" V than residual fuel pressure only when said engine" is into said pressure chamber, a lubricating oil inlet openly connected with said engine lubricating'oil'svstem, a pressure responsive valve connected intermediate said oil inlet and said fuel pressure chamber and actuated upon a decrease of fuel pressure to a predetermined value to open and admit lubricating oil intosaid fuel pressure chamber for accelerating engine ignition.

9. In a fuel supply system for a compression ignition engine having a lubricating oil system, a fuel inject-ion pump for pumping fuel to said engine and comprising'a casing having a fuel inlet, affuel outlet, 'a fuel pressure chamber openly connected with saidfuel outlet, means in said casing intermittently pumping fuel under pressure into said pressure chamber, a lubricating oil inlet openly connected with said engine lubricating oil system, said lubricating oil system having means maintaining a sub- 0 stantially fixed predetermined oilpressure, said injection pump having a check valve connected intermediate said oil inlet andsaid fuel pressure chamber and operable to open only when fuel pressure in said chamber drops below said oil pressure to admit lubricating oil into said fuel pressure chamber to accelerate engine ignition.

11. A fuel supply system for a, oompression ignition 10 engine comprising a fuel injection pump for delivering fuel under pressure to said'engine, means retaining downstream of said pump a residual fuel pressure variable 8 relative to engine speed and load, an ignition accelerator supply system having means obtainingpr'essure therein, and pressure responsive means operable in response to a predetermined variation of pressure differential between residual" fuel pressure and ignition accelerator pressure to introduce'ignition accelerator into the fuel delivered to said engine. I

References C ited'in the file of this patent UNITED STATES PATENTS 2,793,629 Neely May 28, 1957 2,811,145 Young Oct. 29, 1957 2,821,183, Roosa Jan. 28, 1958