CA2041442A1 - Fuel system of an internal combustion engine - Google Patents

Abstract

FUEL SYSTEM OF AN INTERNAL COMBUSTION ENGINE
Abstract A fuel system comprises a diesel fuel feeding line communicating by one end with a fuel tank and by the other end with a high pressure fuel pump in turn commu-nicating with engine cylinders connected to an air feed-ing line, and a gas feeding line whose one end is con-nected to a gas source and the other end is connected to a Venturi tube communicating with the air feeding line. A pedal is operatively connected to a rack of the pump and to a gate provided in the gas feeding line, The fuel system is further provided with a sole-noid for limiting the movement of the rack of the pump to one of the extreme positions "diesel fuel" or "gas fuel" electrically connected to a switch. The switch is electrically connected to a solenoid-operated valve positioned in the gas feeding line. This line also includes a gas pressure regulator. The rack is operati-vely connected to a pneumomechanical valve connected to the Venturi tube and to the gas pressure regulator.
The proposed fuel system can be used in wheeled vehicles, such as trucks 3 to 120 tons in load-carrying capacity, and can ensure a 70 to 80% reduction the amount of diesel fuel consumed.

Description

2 ~ 2 ~UE~ SYSTE~ 0~ AN INTERNA~
COMBUS~ION ENGIN~

This i~ention rela~es to internal combu~tion engi-nes, and more particularly to a fuel ~ystem of an inter-~al combustion diesel engine operating on a gaseous fuel.
~ he in~ention can be used with success in a compres-sion i~nition internal combustion engine opera~ing ~i-multaneously on liquid and gaseous fuelæ and in~talled in truck 3 to 120 ton~ in load-carrying capacity or in a bus.
~ he ever i~creasing ecological demands and the need to save the nonrenewable re~ources of liquid oil ~uel haYe made machine engineers search for alter~ative ~uels for internal combustion engine~.
At present, a gaseous guel, particularly natural gas, i3 viewed as a major replacement for the liqui.d motor ~uel~
lhe natural ga~ is plentiful in resources, ha~ a high calorific power, e~cels liquid oil fuels, and is ideàl for motors, Gas spark igni-tion ~Otto cycle) engi~e~
have found wide use in many countries (particularly in Italy, the Netherlands, New Zealand, ~rance, Canada, U3A and Japan).

The use of a gaseous ~uel in diesel engine vehicles very popular in the vehicle ~leet is inconVenie~t because o~ a hi~her spontaneous ignitio~ temperature tha~ that o~ the diesel PuelO ~here~ore, the use of gas fuel in diasel3 is possible to two manners:
(1) by converting the diesel engine into a gas fuel en~ine with spark (or pilot-flame) ignition; or (2) by igniting an air-gas mixture throu~h-feedi~
a small quantity o~ fuel (pilot inaectio~) ox by using a dual-fuel engine~
The ~irst leads to irreversible ~tru¢tural changes and to a certain reduction in fuel ef~icieno~ ~f the engi-ne; it is mos~ly used in statiOnary diesel engines feed-ing ~rom ~a~ linesl or i~ ~ow~ buses running on routes coming across 6as re~ueling stations.
The use of dual-~'uel engines is more pre~erable in areas where commercial gas reserves are plen~i~ul~ or where there are netWorks of gas line~ and gas stations.
When used i~ trucks a~d buses equipped with high power diesel engines, thi gi~es the following advantagesO
(1) an up to ~0% saving in the die~el fuel (thanks to mixing it with gas);

2 ~ 2 ~ 2) reduction in smoking of exhaust gases ~y a ~ac-tor of 2 to 4;

(3) a 1.5 to 2.0 time~ reduction in the ex~aust s~lid~;

(4) reduction in the noise level by 1.5 - 5~0 dB~
(depending on the basic operation process).
Ilajor di~icul~ies associa~ed wi~h designing aut~
mobile diesel e~ine~ o~erating on a mi~ture o~ gas and ~iesel fuels reside i~ ~hat they are inten~ed ~o ~unc~ion within wide and ~ast-changing ope~ating conditions which compliGa~e at~aining t~e optimum ratio between gas, die-sel fuel and air~ e~Iective combustion9 ~igh ~uel effici-ency and low ~uel soot emission.
In addition9 it is important that the inter~al com~us-tion eL~i~es ha~e equal power capacity when operatl~g aither on the diesel fuel or on a mixture of diesel ~uel and air, as well as be capable o~ operabi~ely switch-i~g from one type of' ~uel to ~he other.
Irhere is known a ~uel s~stem of' a~ internal combus-tion compres3io~-lgnition engi~e operatin~ on a diesel fual and ~as and mou~ted o~ a marine vessel adapted for transportin~ a liquefied ~atural gas (of. 3 US~ A, 3,406,666).
~ his prior art system includes a ga3 feeding li~e connected by one end of a source of gas in the form of a reservoir containin~ a liqua~ied ~atural ga~g a~d by the ot~er e~d to t~e engi~e c~linders where the gas i~

2~41~2 L~

mi~ed wi~h air conveyed ~rom an air feeding 1i~ and a diesel fuel feeding li~e connected by one end to a source ~f diesel fuel9 suc~ as a diesel ~uel ~ank~
a~d by the other end connected to a pluIIger-type high pressure ~uel pump. ~he pump communicates by wRg of high pressure pipes with fuel injec~ors positioned in bhe cylinders of the internal combustion en~ine i~ turn communicable with the air feedi~g line. ~he ~ystem ~urther comprise~ a control link in the form of a pedal operati~el~ connscted to an actuat~ng li~k9 SUC~ as a rack, o~ the hig~ pressure fuel pump~ and an actuating link, such as a rack of a ~econd pump acti~g to engage clo~ing element~ of gas ~alves. The second pump is also a plun6er-type hi~h pressure pump havin~ a sprin~-loaded rack controllin6 the cyclic feed of the diesel fuel in re~ponse to the load. ~he system i~ al~o provided with a mean~ for limiting the movemen~ of the actuating link, particularlg~ bhe rack of hig~ pressure fuel plLmp~ con-nected to the casing of said pump and ha~n~ the form of bellows whose in~erior is con~ected to the gas feedin~
line through a pressure re~ulator controlled by the drive. The ~as feeding lin~ is p~ovi~ed with a control valve. The in~erior of each reservoir overlying the sur-~ace of the liquefied gas communicates with a hèader in turn con~ected to the gas feeding line through a pipe.
This latter pipe has a heat e~chan~er ~or preliminarily ~0~1~42 heati~g a ~lo~ o~ gas conveyed throug~ the valvs to the stages of an axial centrifugal compressor who e shaft is connec~ed to the s~aft o~ an electric motor control led by the operatorO In order to avoid emergencies9 the pipe communicate~ with a pipe ~or dischargi~g the gas to the atmosp~ere via a safety val~eO
~ he e~gine i8 started by caus~ng the high pressure fuel pump to feed the die~el fuel to the injector~ of the en~i~e cylinders.
AB the natural gas i8 fed to the engi~e cylinders9 ~ressure inside the bellows ~row~ due ~o cha~ging ~he position Qf the gate of the ~as pressure regulator ansuring com~unication of the pressure l m e of the compressor with the interior of t~e bellows. The t~us increased pressure in the interior of the bellows causes compres~ion of the spring and movemen~ of the ~to~ to limit the travel of the rack of the high pressure fuel pump to an extent corres~onding to a pilot inJectio~.
~ pressure produced by the worki~ medium of the second pump cau~es the closing elemen~s o~` the gas valves to open and the ~as is admitted to the cyli~ders whereto the atmopheric air has already been admitted~ Mi~ing of the ~as and air takes place in eacn engine cylinder, and the mixture i5 ignited by a diesel fuel flame.
~ he aforedescribed prior art system is characteriz-ed by low consumption o~ the diesel fuel at steady-state 4 ~
6 ~

operating condition~ of the marine eD~ine. Co~Yersely, vehicles intended to ~ravel on unsurfaced roads CannO~
be equipped with thi~ known sys~em ~ue to slow xesponse and 1G~ adaptability to VariatiOns in t~e ve~ocity a~d load characteristics of the engine.
Attempts to pro~ide a compression combustion engine operating o~ a mi~ture of natural gas and air a~d used in ~heeled vehicles resulted in a ~uel system of an L~ternal combus~ion engine operating on a gaseous fuel (cf., pamp~t ~ ~he "rartarini" Company, ~taly)~ rhe ~uel system comprises a diesel fuel feeding ~ine commu;
nicating by one end thereof wi~h a source of diesel fuel, Quch as a diesel fuel tank, and by ~he other end with a high pressure fuel pump i~ turn communicating with the engine cylinders connected to an air fèeding line and a gas feeding line connected by o~e end with a g~8 source, such as a t~nk containing compressed Qr liquefied ~as, and by the other end connected to a mea~s for mixing gas with air which communicates wit~
the air feeding line. In this known s~-stem t~e control link, such as a pedal, is operatively co~nected to an actuating link, such as a rack~ of a high pressure fuel pump a~d to an actuating link in bhe gas ~eedin~ linec ~he system is also ~rovided wit~ a source of electric current connected to a switch. ~nen the diesel engine is intended to operate on a mi~ture o~ diesel and gaseous fuels, ~here is provided a me ns ~or limiti~; the move-2 ~

men~ Q~ tho ac~uating link of the ~igh pressure fuelpump connected to the housing ~f said pump and electri~
cally wared to the switcho ~h~ k of the mea~ ~or limiting th~ moveme~t o~ t~e actuatLng link of the high pre3sura fuel pump is connec~ed to a drive for e~ect-ing ~t~ moveme~t to one of two extreme positions "diesel ~uel't or "gas fuel"a The gas feeding line accommodates a solenoid operated valve electric~lly co~nected ~o the switch. ~ ga~ pressure regulator i~ further provided in this line downstream o~ the flow o~ gas a~ter the sole-noid-operated val~e and be~ore the actuatiag link. Pr~-vided in the gas feedin~ e at its ~ortion between the compressed gas cylinder and solenoid-operated ~alve is a valve for filling the ~as tank with compressed gas, whereas the ~ortion of tnis line betwee~ the actua~in~
lin~ and mixing means accommodates a flow reRtrictor to limi~ the ma~imum gas flow. ~he ~as pressure regula-~tor is pro~ided with a heat exchan~er to preve~t freez-ing of its valves as the gas is throttled. ~he heating side of the heat exchanger communicates with t~e water packet o~ -the en~ine. To ensure a pilot injection of the ~iesel fuel~ the housing of the hi6h pressure ~uel pump has a stop which functions as the means for limiting the mo~ement o~ the pump rack. ~he stop bas a mechanism ~or moving it coa~ially ~ith the rack. lnis mechanism has a housing with its interior separated by a membra~e ihto two cha~bers. On~ such chamber communicates v~ith the compressed air line, whereas ~he other accommodates a rod element co~nec~ed to the membra~ce a~d to t~e stop.
~he compressed air line accommodates a second solenoid--operated valve electrically connected to t~e electric current source. A cuto~f switch is provided in the circuit between the electric current source and chan~e--over switch. The system also includes two electrically interconnec~ed swi~ches9 each connected to ~he air feed-ing line. The switch ~or limiting the maximum rotation cf the engine sha~t is electricall~ connec~ed to a chan~e=
over switch, whereas the switch for contxolling t~e mi-nimum rpm of the engine is electrically connected to the solinoid-operated val~es.
However, one disadva~tage of this known system is that it is not su~iciently reliable in operation due to excessive number of switches a~d valves. Another reason for insuf~icient reliability of the known ~uel sy~tem of an internal combustion engine is vari~ions in underpressure in the air ~eeding llne caused by c~ocking o~ the air ~ilter resulting in freguent engagement of the solenoid-operated valve for controllin~ t~e maximum rpm of the engine shaft~ T~is is turn leads ~o feeding the engine cylinders with the diesel ~uel to result in low fuel ef~iciencyO
It is an object Q~ the present i~vention to provide a fuel system o~ an internal combustion engine which ~vould operate more reliably when ~ed by gasO
A~other ob;ect is to provide a fuel ~y~tem o~ an in-ternal combu~tion engine which ~ould be more ~uel efficient.

2 ~ 2 One more object is to provide a fuel sys-tem of ~n in-ternal combu~tion engine which would be more adaptable to ~ar~ing road co~ditions and loads.
These and other objects of the invention are attained by that in a fuel s~stem of a diesel engine comprising a line for feeding a diesel fuel communicating bg one end thereof with a source of diesel ~uel, and b~ the other a~d with a high pressure fuel pump which communicates with cy-linders of the engine connected to an air feeding line~ a ~as ~eeàing line having one end tbereof connected to a gas ~ource, and the other end con~ected to a mean~ for mix-ing the gas ~ith air oommunicating wi~h the air ~eeding line, a co~trol link operatively con~ected to the actua-ting link of the high pressure fuel pump and an actuating link positioned in the gas ~eeding line9 an electric cur-rent source, a switch electrically connected to the elect-ric current source, a~d electromechanical means for li-miting the movement o~ the actuating link of the dri~e o~ the high pressure fuel pump co~nected to a casi~g of said pump and electrically con~ected to the switch, the link of the electromechanical means for limiti~g bhe moVemen~ o~ the actuating link o~ the hi~h pressure ~uel pump being connected to a drive for moving i~ to one o~
the e~treme positions "diesel ~uel" or "gas ~uel", a solinoid operated valve electrically co~nected to t~e swi~ch and positio~e~ in the gas feeding line accommodat~
ing a gas pressure regulator downstream of the flow gas a:l~ter the solenoid-operated val~r~ a~d be~or~ the actuatinæ link in the gas feedin~ line? acc~ di~g to t~e invention, th2 actuating link o~ the hig~ pressure ~uel pump i~ provided with a pneum~mechanical valve co~ected to the means ~or mi~ mg the ~as wit~ air and to the gas pressu-re regulator.
~ his coDsuruction of the proposed fuel system o~ a die-sel engine enqures reliable termination of the flow of gas i~ response to reduced feed rate R the diesel fuel to below the pilot ignition quan~ity. ~he advantage has been attained by connectin~ the pneumomecha~ical valve to t~e ~uel pump rack. ~ovement o~ the rack of a position cor-responding to a feed rate of the fuel below t~e pilo~ i~ni-tion quantity terminates t~e admission of air to one of the actuatin~ links o~ the gas pressure regulator where,b-~it cha~ge~ its position to cut off` the flow of gas to the mea~s for mixing thc gas wlth air.
Preferably, the pnelmomecha~ical ~alve communicates with the air feeding line in a zone before the means for mixing the gas with air downstream of t~e air flow.
~ his constructior. OL the proposed fuel system provides a flow of gas proportional to the flow of air passing throu~h the choked ~ilter ensuring stable operation o~ the en~ine irrespective of the c~a~ging resistance of the fil-ter to the flow of air conveyed t~erethrou~h.
It is ad~isable that the pneumomechanical valve had a housing accommodating axially a rod for moveme~t in r 2 0 ~ 2 a guide, one end O~ the rod being en~a~eable with t~e actuating lin~ o~ the hi~ pressure fuel pump, w~ereas t~e other end eD~ging with a closing element o~ tnis valve forced to a valve seat by a s~rin~ bearL~g by one end on the wall of the housing, and by the other end on the closing element to separate the interior of th0 housing communicating with the means ~or mi-~ing the gas wit~ air from the càvity which communicates with the gas pressure regula~or.
The above construction of the valve ~acilitates reLi-~bl~ communication of the cavity whers the pressure is atmospheric with the ca~ity ~here the pressure 1~ below the atmospheric, which leads to a reduction ~n the presqu-re in the gas pressure regulator causing a pressure diffe-rential acting on the actuating link of the pressure regu lator. Under the action of this pressure differe~tial the actuating li~k o~ the pressure diY~erential acts to close the ~alve feeding the ga~ to the mean~ ~or ml~ing the gas with air.
~ he valve is structurally simple and t~erefore reli-abla in operation.
The proposed fuel system is embodied in an internalcombustion engine having a volume displacement ~ ~ IO,35 1 at an effective power of ~ ~ I4I ~W and rpm ~ ~ 2IOO.
The system can be used in any wheeled vehicle, such as two~ and intercity buses,and ca~ reduce liquid fuel co~-sumption b~ 7O-~O~.
Tbe i~ve~tion will now be described in ~reater detail with reference to a ~peci~ic embodime~t thereoi~ taken i~

_12_ conjunction wit~ the accom~anying drawings9 in which:
O~1Q
Fig~ 1Ais a schematic representation of a fuel s~stem o~ a diesel e~ine operating on a gaseous ~uel;
~ ig. 2 is an enlarged lon~it~dinal section of a pneumomechanical valve positioned on the cover plate o~
a pump;
Fig. 3 is an enlarged lon~it~dinal sectional view o~
the pneumomechanical valve during stable o~erating condi-tio~s o~ the engine; and Fig. 4 sho~vs the same as represented in Fig~ 3 during u~stable operating conditions n~ the enæine.
~ uel system of an internal combustio~ engine accor-~in~ to ~he in~ention used in t~a "Ikaxus"-typs bus comp rises a line 1 for eeding a diesel fuel (Ei~. 1) connect-ed by one end 2 thereo~ to a source of diesel ~uel in the form o~ a ~uel tank 3 a~d by the o~her end 4 via a low-pres ~ure ~uel pump 5 to a hi~h pressure fuel pump 6~ The fuel pump 6 is mounted on a crankca~e of the internal combus-tion en~ine 7. The fuel pump 6 communicates by way o~ hi~h pressur~ pipe~ 10 wit~ fuel i~ectors 8 positioned inside cylinder~ 9 of the internal combustion e~g~ne 7~ The head e~d (not ~hown) o~ each cylinder 9 o~ the eng~ne 7 communicates with an air f eedi~ line 110 ~he fuel system includes a gas feedin~ e 12 cor;~lected by one e~d there-OI via a ~lalve 13 ~o a source 14 of gas, a~d by the other end to a means 15 for mixing the ga~ wi~h a~, The gas source 14 has the form ~ a oom~ressed ga~ c~linder pro-vided with a means '16 for refilling the ¢;yli~derO The mear~s 15 for mixing tbe gas wi~h alT~ is positiorled in t~e , 2 ~ 2 air fseding line 119 a~d has t~e form R a V~tura tube 17. ~he control linkage ha~ the form o~ a pedal 18 ope-ratevely connected to a~ actuati~g link of tha pump 6.
~ha kinema~ic linkage include~ a rod 19 connected to the pedal 18 and hi~gedly associated with a~ arm ~ o~
a lever 21 Qecured on a pin 23, the other arm 22 thereo~
`oeing hingedly con~ected to one end of a rod 24. ~e o~her end of the rod 24 is linked with an intermediate link 25 co~nected to a rack 26 (Fig. 2) ~nctioning as the actuating link o~ the pump 60 ~h~ pedal 18 (~ig~ 1) i3 positioned i~ th~ driver's cab~ and is enga~ed by the foot of the driver. The intermediate link 25 is connect-ed by a rod 27 to an actuating link lscated in the gas feeding line ~2 and having the form of a gate 28 secured on a pin 30 in a casing 29 arran6ed i~ the gac feeding line 12~ The pin 30 is secured on a pipe 3~ positioned in the zone where it commu~icates with the ~enturl tube 17.
A source 32 of electric power in the form of a storage battery i~ electrically connected to a switch 33. For feedins the diesel engine 7 with gas the feedin~ system if provided with a means 34 for limiting the displace ment of the rack 26 to reduce the feed rate of the die-sel fuel. ~he mea~s 34 i9 positioned at the crankcase of the engine 7, and has a movable stop memb er 35 inte~d ed to engage with the rack 26 and movable by a~ electric ~ield induced in the winding of a solenoid (not shown) ` 2~41~

electrically connected to thc s~itch 33~ The means 34 acts ~o mov~ the stop 35 to one o~ ~he two extreme posi tionss "diesel ~uel~ or "g~s fueln.

.
Provided in the gas ~eeding line 12 downs~ream o~
the flow of gas are a heat exchanger 36 for ~eating t~e gas, a gas pressure redu~g regulator 37, a gas feed-in~ solenoid-operated valve 38, a filter 39, a~d a gas pressure reducing regulator 40. ~he val~e 38 is electri-cally a~sociated with the ~wi~ch 33~ -The gas pressure regulator 40 ha~ two prs~surereducing stages for the gas pressure to be reduced in the first such sta~e to 0.2 ~Pa, and in the second sta~e to the atmospheric~ The pressure re~ulator 40 includes a housing 41 with the inte~ior thereo~ separated by a par-tition 42 into two chambers: a medium pressure cbamber 43 a~d a low pressure chamber 44. The partition 42 is pro-vided with an air valv~ 45 inte~ded to communicate the chambers 43 and 44. Provided in the wall of the housing ~1 in the zone of the filter 39 is an air valve 46.
~he chamber 43 is divided by a membra~e 47 into two isolated zones 43a and 43b~ ~e zone 43a communicates with the outside and accommodates a spri~g 4~ engageable with the membrane 47 which is operatively connected with the closing element of the Yalve 46 at the side of the zone 43b. The chamber ~4 is separated by membra-nes 49 a~d 50 into zones 44a, 44b and 44co The zone 44a accommodates a spri~g 51 enga~eable with the membrane 49 operati~ely coDnected at the side o~ the zone 44b to the closi~g ele~ent of the valve 45D ~he zone 44c accommodates a spri~g 52 cooperating with the membrane 50 which is in turn connected a~ the side o~ the zone 44b to the clo~ing element of the valve 45. The zo~e 44a c~mmunicates by wa~ o~ a~ air li~e 53 with the pump 6, whereas the zone 44 communicates t~rough an air lin9 54 with the means ~or mixi~g the gas with air at the smalleYt cross section o~ the Ve~ture tube 177 and ~ith the pump 6.
Raferring now to Fi~. 2, the proposed fuel system of a diesel en~ine is ~roviaed with a pneumomechanical valve 55 ensuring synchronous stops in the ~eed of gas and delivery o~ a~ ig~ition sho~ of diesel ~uel, this valvs 55 being secured at a cover plate 56 of casing 57 of the pump 6. The cover plates 56 is connected to th~ casing 57 by bolts 58. ~he interior o~ the hollow housing 59 o~ the valve 55 is separa~ed by a partition ~0 into ca~ities 61 and 62. ~he partition 60 ~as a threaàed hole accommodating a threaded slee~e 63 (Figo3) whose end serves as a seat of the closing ele~ent in the ~orm of a ball 64~ A shell 65 is threadin~ly connec ed to the threaded end of the sleeve 63, whereas i-ts inner surface serves as a guide for the ball 64. The wall of the shell 65 has radial holes 66~ ~he cavity 62 2 ~ 2 ~ ~6 is separated ~rom the outsid~ b~ a seal 67 a~d nut 68 engaging with the threaded end 59a of the housing 590 A lock nut 69 serves to hold the nu~ 68 in place. The nut ~8 and lock nut 69 have a through xadial hole receiving a ~hreaded end o~ a pipe 71, t~e other and 72 (~ig. 1) OL this pipe communicating with interior 73 ~ the air ~eeding line 11. This interior 73 i~ positioned between a ~ilter 74 for cleaning air sucked in from t~e atmosphe r~ and means 15 for mi~i~3 air and gas. ~ cavity 62 (F~g. 3) of the val~o 55 i8 connected by the air line 53 to tho zone 44a (Fig. 1) o~ thc pressure regulator 40. ~he cavity 61 (~i~. 3) of the valve 55 communicates through the air line 54 wlth the means 15 (Fig. 1) for mixing the gas with air and ~ith the zone 44c of the pressure regulator 4V. In orde~ to communicate tho cavity ~1 (Fig~ 3) with the cavity 62 of the valYe 55, there is provided a rod 75 capable of longitudinal move-ment in a guide 76 threadingly connected to the housing 59. One end 77 o~ the rod 75 engages ~ith t~e ball 64, ~hereàs the other end 78 (~ig. 2) thereof i~ connected by a kinematic linkage 79 to the rack 26 of the fuel pump 6, The kinematic linkage 79 can, for example, have the form o~ an intermediate link 80 co~nected to an engine shaft rotation regulator (not shown). A stop 81 is secured on t~is link 80 to engage ~7ith the end 78 of the rod 75 and hingedly linked with one end o~ a rod ~2, 2 ~ 2 _ 17 the other e~d thereof being ~hxeadingly connected to the rack 260 T~e guide 76 is t~readingly connected ts tha cover place 56 to ensure continuous engag.~ment o~
tne rod 75 with the stop ~1. For reinforci~g the threaded conDe;ction of the guide 76 to the cover plate 56, the latter is provided wi~h plaues ~3 having threaded holes. In order to stop the ~uide 76, the cover plate 5~ has a nut 84, whereas a nut 85 serves to s~op it in the hou~i~g 59. ~he threaded end 70 of the pipe 71 has Q cavity 86 (Figo 4) communicatin~ with the in~erior of the pipe 71 and accommodating a ~pring 87. ~he sprlng ~7 bears by one end thereo~ on the wall con~ining the caviuy oo, a~d by the other end on the surface of the ball 64~ ~he threaded end 70 of t~e pipe 71 faci~g the cavity 62 has a ch~fer ~. The genera~ing line of t~is cham~er 88 and edge 89 of the outlet hole of the shell 65 define an annular slot 90 serving to gr~dually chan~e the pressure inside the zone 44a (~ig. 1). ~ spacer member 91 is proviaed to maintain a continuous undexpres-sure in the cavity 61, ~ he herein proposed fuel s~-stem of a~ internal com-bustion en~ine operates in the following manner. ~1hen starting the engine and during slot idlin~ of the engine a diesel fuel is fed to the cylinders 9 (~ig. 1) of the engine. ~he driver sets the switch 33 to the "aiesel fuel"
position. ~he electric circuit "switch 33 - winding of .~ 18 the solenoid 34" is broken, and the stop 35 allows th~
mo~ement o~ the rack 26c RotatiOn o~ the h~fb (not ~ho~n) o~ the engine 7 actuates the pum~s 5 and 6c ~hæ ~uel ~ conveyed by the pump 5 ~rom the tank 3 along the li~e 1 to the pump 6. The plungers of the pump 6 force the fuel alo~g the high pressure pipes 10 to the ~uel injectors 8 of each cylinder 9. ~ir is fed along the air line 11 to each cylinder 9 as it execu~es its downward stroke. Duri~g the compression stroke at the ~op dead centre of the pi~ton the ~uel is i~jected to e~ch cylLcder 9 throug~ the correspond~g i~jector 8.
~he fuel is then ignited to result in a sudden increase in pressure in ~he combustion chamber of the respective cylinder 9. ~his pressure acts on the piston to cause its downward movement converted i~to rota~ion of the sh~ft of the engine 7, and the en~ine 7 therefore operat-es on the diesel fuel.
For operating on a gas ~uel the switch 33 is set to the "gas fuel" position. The s~itch 33 closes the electric circuit fox feeding the winding of the sole~
noid 34 under the action o~ an elec uromagnetic f ield causing the movement of the stop 35. ~he stop 35 pre-vents movement of the rack 26 to its full stroke and thereby limits the quantity of diesel ~uel to a measur~
ed "ignition shot". Application of pressure to the pedal 18 leads to turning of:the lever 21, movement of the rod 24 _ 19 ~urning o~ the link 25~ movement o~ the rod 27, and turning of t~e gat~ 28 to a po8ition en8uring th~ a~mis~io~ 0~ a gas flo~ to t~e minimum cross sec-tio~ of the ~enturi tube 17. ~he swi~c~ 33 completes th~ electric--circuits ~or feedI~g the winding of the ga feedi~g solenoid-operated val~e 33 for the gaa to flow from the ~as source 14 via the valve 13 to the 6as ~eeding line 12 and then to the heat exchanger 36 where the ga8 i9 heated. The heated gas t~en ~lows through the gas pressure reducing regulator 37, sole-noid-operated valvo 38 and filter 39 to the gas pres-sure regulator 400 Therewith, the valves 45 and 4~
are open under the action of the respective sprin~s 51, 52, and 48~ Pressure in the chambers 43 a~d 44 grows, whereby t~e membr~nces 49, 50 a~d 47 are caused to move, and the valves 45 and 46 close, ~he valve 45 i8 fir8t to close, and the ga3 pres~ure in the ch~mber 43 continues to grow urtil closing of the valve 4~. The gas is conveyed from the chamber 44 to the means 15 for mi~ing it with air through the open gate 28. As the flow of gas escapes from the chamber 44~ the pressure in this chamber 44 drops for the membranes 49 and 50 to move ~nder the action of a press~ie difLerence in the ~o~e~ 44a, 44b, 44c and 44d. In turn, their move~
ment causes the movement of the links of the kinematic linka~e with the closing element of the valve 45. The latter opens, and the ~as flows ~rom the chamber 44 , ~ .

2 ~ 2 --along the pipe 12a and through the open gate 2~ ~o th~
Ve~turi tubo 17 where it is mixed with air to result a gaseous ~ual. This fuel is admitted to th~ cyliDders 9 of the eDgine 7 along the pipes 11al Ths 'pilot in jection quantit~" o~ the diesel fuel e~caping from the nozzle ~ to one OI tne c~-linde,s 9 ignites the gaseous fuel admi~ued thereto. The process of opening and closing proceads continuou~lyO ~s the eL~ine operates ~om the minimum to the maximum rpm, i.e., at the stabilized oparating co~ditions9 the end o~ the rack 26 (F~g~ 2) ~ails to act on the rod 75 (Fig. 3) throu~h its kinema-tic linkage 79. The ball 64 iq therefore ~orced by the spring ~7 to the seat of the sleeve 63. A~ underpressure is propagated from the i~terior of the Venturi tube 17 via the air line 54 o~ly to the cavity 61 of the pneu~c-mechanical valve 55. When forced to the seat of the sleeve 63, the ball 64 discommunicates the cacities 61 a~d 62 Of the valve 55. ~s the cavity 62 communicat-es the air line 53 with the pipe 71, the zone 44a (Fi~. 1) of the gas pressure regulator 40 communicates via the cavity 62 with the interior 73 of the line 11 between the filter 74 and means 15. ~he pipe 71 co~municates ~;ith the air line 53 through a gap between the edge of the pipe 71 facin~ the ball 64 and surface o~ the ball 64 and annular slot 90. As the resist~lce of the filter 74 ~roYJs due to its fouling, tne pressure of air at 2~4~2 _ 21 this portion changes to result ~n a change in th~ pr~s~u-re Q~ air L~ the zone ~4a~ ~ouling or chocking of the er 74 cauge~ a change in pressure in the Venturi tube 17 which L~ ~urn leads to a v~riation in t~e ~low rate of gas in t~e gas feeding li~e 12 and re~uction in ~he pressure of gas i~ the ~one 44b exerting action on the membra~e 49 at the other side. hn equal reduction in pressure in the zones 44a and 44b leads to a balanc-ed stat~ of the membrano 49 thereby en~uring that the ~low rato Of ga~ corresponds to the flow rat~ o~ air passing through the choked filter 74. Reliable function_ ing of the ~uel system is ensured by pneumatic communica-tion between the interior 73 and zono 44a of the gas pressure regulator 40; the working medium being cleaned in the ~ilter 74, whereby a~ extra air cleaning filter can be dispensed with.
At an excessive rate of rotation of the shaft o~ the engine 7 the intermediate link 80 (Fig. 2) co~nected to bhe engine shaft rotation regulator acts to mcve the rod 82, and the rod 82 moves the rack 26 to a posibion corresponding to a lo~Jer feed rate of the diesel ~uel (Vi2., to the right) and minimi~ing the ~uel ~eed rate bo zero. As the rack 26 moves to the right, the stop a1 acts on the end 78 o~ the rod 75 by its other end 77 (Fig. 4) bo move the ball 64 along the inner surface of the shell 65 thereby ensurin~ communication of the ~. . .

2 ~ 2 ca~ities 61 and 62 Of the valve 55 via the radial holes 66. ~hi~ in turn results in a reduction in pressure in tha zone 44a (Fig. 1) to a level determined by the un-derpre~sure in tha minimum cross section of the ~enturi ~ub~ 17.
A dif~erence in pressure in the zones 44a and 44 b 0~ ~he pressure regulator 40 caugeS the membran~ 49 to mov~ resulting in moveme~t of the links of the kinema-~ic linkage with the closing element o~ t~e val~3 45 for tho latte~ to close. Feed~ng of the gas to the mi~-ing means 15 is terminated thereby reducing the gas feed to zero as the rotation rate of the en~i~e sha~t exceeds the nominal to avoid racing of the engine. As the en~ine sha~t starts to rotate at a below-nominal rate, the inter_ mediate link &O (Fig. 2) moves the rod 82 for the latter to displace the rack 26 to th~ left~ When movin~ the rack 2~, the stop 81 departs from the end 7~ of the rod 75.
~he ~orce of spring ~7 acts to move the ball 64 and seat i~ into the seat o~ the threaaed ~lee~e 63~ ~he cavities 61 and 62 Of the valve 55 (Figo 3) discommunicate. Air --.:
staxts a~ain to flow from the interior 73 (Fig. 1) alon~
pipe 71 to the cavity 62~ ~rom the ca~ity 62 (Fig. 3) ~e air flows along the line 53 to the zone 44a (Fig~ 1) to result in a growth o~ pressure thereinO ~qualization of pressures in the zones 44a and 44b causes the retur~ o~
the membra~e 49 to the initial position, the Yalve 45 `` 2 ~ 4 2 move~ to connect ~he c~ambers 43 and 44 and feed th~
~as to the mea~s 15 fcr mixing it with airO ~o~emen* o~
the ball 64 causes the air to flow from the p~p~ 71 to the increasing clearance betwaen i~q edge and ~ur~ace Qf the ball 64 and the flow restrictLng annular slot 90 to the ca~ity 62, which is followed by a gradual increa~
se in pressure inside the zone 44c thereby reducing tke e~ect of sharp pressure fluctuations on the operation o~ the system and facilitatin~ the acceleration charac-teristic~ o~ a vehicle drive~ by the internal combustion engino having the herein proposed fuel feeding system.
The fuel ~eeding sy3~em ensures termination of gas ~eed-in~ at a position of the rack 26 of the Yuel pump 6 cor-responding to its position below the'~ilot i~Lition qua~tit~'`. In this case, as has been described heretofo-re, the rack 26 acts through the kinematic linka~e 79 and rod 75 to move the ball 64 from the seat of the sleevs 63. Communication o~ the cavities 61 and 62 resultq in a pressure drop in t~e zone 44a, whereas a higher pres-qure in the zone 44b de~l`ects the membrane 49 which in turn causes closing of the valve ~5~ Feedin~ o~ the gas fuel to the means 15 stops, thereby preventin~ its accumu-lation in the exhaust gas discharge system, particularl~
in the ex~aust muffler, to ensure reliable operation OI
i,he engine at virtually any operating conditions.
In view of the aforedescribed, the herein proposed ~uel system of an i~ternal combustion engine ensures a 2 0 ~ 2 ~ 2~ _ coordin~tad, ~imulta~eous and desired limitation in the f~ed rats of gas accompanied by a reduction in, or eve~
termi~ation ~ th~ ~eed of th~ diesel ~uel to re~ult in a more relia~le and controlled operation of the fuel systemO Th~ propo~ed fuel ~ystem o~ an internal combu&-tion angine is structurally ~mple, a~fording to improve tho performance of vehicles~ ~he gas feed rate correc-tion in responae to choking o~ the air cleanin~ filter i3 ~unction~lly integrated with the ~as feed~
~ ajor ad~an~ages of i~ter~al combustion e~ginea opera~ing on a gas fuel are~
low fuel c06t;
- hi~her ecolo~ical safety;
- reduced wear of cylinders and pistons; and - longer service life of the motor oil.

Claims (3)

1. A fuel system of a diesel engine operating on a gaseous fuel comprising:
- a source of diesel fuel positioned at the frame of a vehicle;
- cylinders of the diesel engine intended to burn the fuel and convert the heat of combustion into mecha-nical work;
- a diesel fuel feeding line having two ends, of which one end communicates with said source of diesel fuel;
- a high pressure fuel pump communicating with the other of two said ends of said diesel fuel feeding line and with said cylinders of the diesel engine;
- a housing of said high pressure fuel pump;
- an air feeding line communicating with said cylin-ders of the diesel engine;
- a gas source mountable on the frame of the vehicle;
- a gas feeding line having two ends of which one communicates with said gas source;
- a means for mixing the gas with air positioned in said air feeding line to communicate with this line and with the other of said two ends of said gas feeding line;
- an actuating link of said high pressure fuel pump intended to change the flow rate of the diesel fuel conveyed to said cylinders of said diesel engine;
- an actuating link positioned in said gas feeding line and intended to change the flow rate of gas conveyed to said means for mixing the gas with air;
- a control link mountable of the frame of the vehicle and acted upon by the driver of the vehicle;
- a link intended to change the flow rate of the die-sel and gas fuels corresponding to the operating conditions of the diesel engine operatively connected to said actuat-ing link of said high pressure fuel pump and to said ac-tuating link mounted in said gas feeding line;
- a kinematic linkage connecting said control link with said link;
a gas pressure regulator intended to reduce the pressure of gas conveyed from said gas source to said means for mixing the gas fuel with air and positioned in said gas feeding line downstream of the flow of gas before said means for mixing the gas with air;
- pneumomechanical valve for stopping the feed of gas to said cylinders in response to reduction in the flow rate of the diesel fuel to below the pilot ignitnion quality connected to said means for mixing the gas with air and to said gas pressure regulator;
- a source of electric current mountable on the frame of the vehicle;
- a switch electrically connected to said source of electric current;
- a solenoid-operated valve positioned in said line for feeding the gas fuel downstream of the gas flow before said gas pressure regulator communicating therewith and electrically connected to said switch;
- an electromechanical means for limiting the travel of said actuating link of said high pressure fuel pump connected to said casing of said high pressure pump and electrically connected to said switch;
- a casing of said electromechanical means;
- a link of said electromechanical means for engagement with said actuating link of said high pressure fuel pump assuming a position corresponding to the pilot ignition quantity of the diesel fuel positioned at said electromechanical means.

2. A fuel system of a diesel engine as claimed in claim 1, comprising: a pipe having one end thereof com-municating with said pneumomechanical valve and the other end connected to said air feeding line in a zone downstream of the flow of air before said means for mixing the gas with air.

3. A fuel system of a diesel engine as claimed in Claim 2, comprising:
- a hollow casing of said pneumomechanical valve;
- a partition positioned inside said casing to divide its interior into two cavities;
- a sleeve with a seat positioned in said partition;
- a shell connected to said sleeve to embrace it about the outer surface and having through radial holes;

- a closing element of said pneumomechanical valve separating the cavities of said casing, positioned in the seat, and embraced by the inner surface of said shell;
- an end of said pipe secured in said casing of the valve secured in one of two said cavities and extending in line with the longitudinal axis of said casing;
- a cavity made in said end of said pipe extending along the longitudinal axis of said casing at the side facing said closing element;
- a spring positioned in said cavity to engage by one end with said closing element and by the other end bearing on the wall of said pipe;
- a rod for removing said closing element from the seat of said sleeve, this rod being positioned inside said casing to extend in line with its longitudinal axis and having two ends, of which one engages with said clos-ing element, whereas the other is operatively connected to said actuating link of said high pressure fuel pump;
- a first air line whose one end communicates with one of said two cavities of said pneumomechanical valve accommodating said rod, whereas the other end communicat-es with said means for mixing the gas with air;
- a second air line whose one end communicates with one of said two cavities of said pneumomechanical valve accommodating said closing element, whereas the other end communicates with said gas pressure regulator;

- a chamfer made at the end of said pipe at the outside;
- an annular slotted clearance defined between said chamfer and the hole edge of the shell.