US2537371A - Fuel injection arrangements in internal-combustion engines - Google Patents

Description

Jan. 9, 1951 PETERSEN 2,537,371

FUEL IN TION ARRANGEMENTS IN v INTERNAL- MBUSTION ENGINES File Jan. 25, 1946 O. PETERSEN attorney Patented Jan. 9, 1951 IlJNl-TED FUEL INJECTION ARRANGEMENTS IN INTERNAL-COMBUSTION ENGINES Ove Petersen, Gentofte, Denmark Application January 25, 1946, Serial .No. 643,282

In Denmark February 4, 1943 Section 1, Public Law 690, August" 8 1946 Patent expires February 4,1 963 Fuel injection arrangements. are known for internal. combustion-engines. with two fuel pumps working. in series; The first, so-called normal, fuelpump is driven by the engine, and the pressure pipe of the pump opens out through a spring-loaded suction valve in the pressure chamber of: the second fuel. pump, the so-called pressure pump, which has a. d'iiierential piston and works in accordancewith the principle disclosed in. British Patents Nos. 226,523 and 419,510, the piston being-driven by the compressionand combustion-pressures in the cylinder. ,From the pressure chamber of this'second fuel pump a pressure channel leads" to an automatic, springloaded; fuel valve in' the cylinder of the engine. From. the said pressure channel a relief channel is branched oif, which ends either in the suction pipe of the-pressure pump or in a closed liquid chamber of the necessary, volume. In the relief channel is inserted a control member-preferacly 'a slide valve formed by the piston of the pressure pump-which opens when the fuel valve .in the cylinder-is to close. The arrangement has the drawback that it requires two pumps working in: series, of which the first measures out the quantity of oil to be injected into the cylinder by the second; pump, the pressure pump. Furthermorethere is the essential drawback that the moment of opening of the fuel valve will depend in part on the spring pressure on the automatic valve, in part on. the pressure on the oil, which pressure is in turn determined by'the compression inthe engine cylinder. 'The arrangement cannot therefore offer any exact determination :of. themoment of the commencement of the fuel injection-into the cylinder.v

Furthermore another fuel injection arrangementis known with two pumps working in series. The first and normal fuel pump measures out thequantity'of fuel which the other pump is to inject into the cylinder. The fuel is delivered from the first pump toan accumulation chamber 'whi'cl'rzisprovided-with a spring-actuated accu- -mulator piston which controls an overflow chanm1. From-the accumulation chamber the fuel is :pressed: through a non-return valve into the pumping chamber for the second pump, the so- .called pressure pumpgwhich has a difierential :piston' which during: the pressure stroke is driven :i-n part by a spring, in part by the compression- ;and combustin-pressure in the cylinder. From ithe pressure chamber of the'pressure pump the ntel flows of through a valve to a pressure pipe fwhich: terminates: in a spring-actuated automatic iueliinjectionvalve in thecylinder. In the said 5 Claims. (Cl. 123139.)v

pressure pipe a.control member is inserted. control member consists of a: slide valvev which is spring-influenced in such a way that-unless the the spring pressure is overcome-it will close the pressure pipe. The said s ide; valve is: actuated for'opening by means. of a lever that is rotatable around a shaft, the other endv of which lever is actuated indirectly from aso-ca'lled negative" cam on acam disc. on a control shaft. The said slide valve control. is so arranged that the slide. valve will open the pressure channel to the automatic fuel valve at the moment when the fuel injection into: the cylinder is tocommence. The constructime thus constituted gives a good determination of the point of commencement of the injection but gives no good determination of the termination of the injection,.the construction lacking means for the elimination of the pressure in the valve at the termination of'the injection. Moreover, the construction'has besides the drawback that there is no relief channel 'communicating with the pressure pipe of the fuel pump, the drawback that the construction requires two series-operated pumps, namely, besides the gasdriven pump furthermore a normal fuel pump. which measures out the quantity of fuel to be injected: and: which through a non-return valve presses the fuel into the pressure chamber of the gas-driven pump and. thereby causes the differential piston of this pump-to be returned into its original position under overcoming of especially thespring-pressure. which. constantly influences the piston in the gas-driven pump.

Furthermore a fuelinjection arrangement is known consisting of a combined fuel pump and injection valve, the rotating differential piston of which is, during the pressure stroke, driven by the compressionand combustion-pressure in the cylinder and is, during the suction stroke, driven by a spring. From a tank the fuel is led to a bore in thecase of the pump, and from this it is sucked through an oil inlet into the pressure chamber .of'the pump. During the pressure stroke the pump piston closes the oil inlet and brings the fuelunder increasing pressure inv the pumping chamber. From the pumping chamber a pressure channel. issues, the first part of which forms a channel in the pump case and the last part of which consists of a bore in the pump piston. Th-isbore terminates in a lower space in the piston, which space is below bounded by a wall in which there are a number of nozzle openings leading into the cy inder. In the lower part ,i c aspiring-loaded non-return valve: is

provided which is opened when the pressure on the fuel overcomes the spring pressure of the valve. Next the fuel will start its injection into the cylinder through said nozzle openings. In the said channel in the pump case, that is in the former part of the pressure channel of the pump, there is a spring-influenced valve, the so-called timing valve. In this a relief channel is formed which can put the pressure channel of the pump in communication with the suction chamber of the pump or the said bore in the pump case. said relief channel in the timing valve can be closed by means of another valve. This other valve can close the relief channel, as with its head it can be brought to abut on the end of the timing valve which projects into the suction chamber of the pump. The said other valve is by means of a tappet actuated indirectly from a cam disc on a control shaft. A positive cam on the cam disc causes the said other valve to first close the relief channel in the timing valve and then a little later open the latter, whereby the pressure channel from the pumping chamber of the pump is opened. When the timing valve is opened the fuel injection into the cylinder will start, and during the pressure stroke of the pump piston the fuel injection will occur at an increasing pressure. The injection period will continue until the mechanically actuated timing valve is closed on account of the cam control and the spring influence. Shortly after the timing valve has been closed, the cam control will permit the other valve to open the relief channel. The construction has the very considerable drawback that the point of commencement for the injection in fact becomes indeterminate, it being necessary to work up a pressure in the last part of the pressure channel and in the space containing the nonreturn valve, before the latter can start opening. The passage of the fuel through the non-return valve and thereby also the fuel injection through the nozzle openings will consequently start at a rather slowly increasing pressure, so that the point of commencement for the injection becomes indeterminate. The termination of the injection is in fact also quite indeterminate, said termination being first and foremost determined by the closing of the timing valve a short time before the relief channel is opened, which will cause the pressure on the fuel in the pressure channel 1 and the lower chamber of the latter to drop until the non-return valve starts and performs its closing motion, all with the result that the termination of the injection is in fact quite indeterminate. the relief channel terminates in the suction chamber of the pump, which can give rise to shocks in the pump.

Finally another fuel injection arrangement is known likewise consisting of a combined fuel pump and injection valve. The suction stroke of the pump piston is caused by a spring, and the pump works in accordance with the said British Patents Nos. 226,523 and 419,510, the stepped piston being during the pressure stroke driven by the compressionand combustion-pressures in the cylinder of the engine. On the pump piston there are a couple of oblique cutting-off edges, which serve for measuring a certain quantity of oil in the pressure chamber of the pump. From this leads a pressure pipe to the injection channel of the valve, which channel ends freely in the cylinder. In the pressure pipe, which is in part made up of the nearly tubular pump piston, is inserted a control member in the form Furthermore there is the drawback that The of a slide valve, which through a spring-actuated control spindle projecting up through the combined pump and valve is driven from a cam shaft. The construction is also known in some modified embodiments, but common to all embodiments is the fact that the pressure channel terminates in an open nozzle, and that in the lowest part of the pressure channel there is a control member in the form of a slide valve or a so-called timing piston valve which on one hand is to determine the commencement of the injection in the best possible way, and on the other hand-when the injection is about to cause acts to such the last remainder of the fuel back into the pressure channel so that the open nozzle is prevented from dribbling. The construction described is very complicated, and as a result of the pressure channel forming a channel open at the end it has the drawback that the moment for the commencement and the initial pressure of the injection are not precisely defined, the opening for the pressure channel by the slide valve causing a pressure drop in the pumping chamber, so that the injection is started at a comparatively low pressure, which is inexpedient for the combustion. The injection is terminated when the pump piston arrives at its innermost position after which the pressure in the pressure channel will drop as the oil in the channel will expand. This relatively slow termination of the injection is a considerable drawback.

The purpose of the present invention is to remedy the said drawbacks by an injection arrangement mainly of the kind mentioned above and thereby ensure an accurate determination of the moment of commencement of the fuel injection as well as the termination of the latter.

More clearly defined the invention relates to a fuel injection arrangement for internal combustion engines of the kind Where the piston of the fuel pump is a stepped piston driven by the compressionand combustion-pressures of the engine, and where the suction stroke of the piston is caused by a spring, and in which fuel pump a helical cutting-off edge, preferably situated on the piston, serves for measuring the quantity of oil intended for injection, and in the pressure channel of which is inserted a control member, preferably a slide valve. The fea ture that is first and foremost characteristic of the invention is that outside the control member, which is preferably formed by a slide valve, the pressure channel of the pump is connected to one or more automatic, spring-loaded fuel valves in the cylinder, and that from the pressure channel of the pump there leads a relief channel leading to a return pipe to the oil tank of the pump, in which channel there is in a way known per se inserted a control member, which is preferably made up of a slide valve formed by the lower part of the pump piston.

By the said fuel injection arrangement a precise determination of the moment of commencement of the injection is ensured by the control member, preferably a slide valve, which is inserted between the pump and the springloaded fuel valve in the cylinder, the stepped piston of the pump being so proportioned that the oil pressure before the said control member or slide valve is so high at the moment, when the control member is opened, that the fuel valve is opened at practically speaking the same moment, i. e. at the first pressure wave. At

the same time there is by a suitable adjustment ass-nan.

of-the spring loading of thecfuel valve'iattained started at the'in iection pressure. most favourable fonthe combustion. .The arrangement also ensures a: precise determination of the termination of .theifuel injection, the quick relief of the pressure in the: fuel: valve attained by the pressure pi-pe being at the end of the injection put in communication withv the said return pipe causing a quick closing of thewfuel valve,so that: the injection is likewise terminated at a pressure favourable: for the combustion, while at the sa-me time by the use of the said return pipe disturb ing pressure variations in the supply pipe-for. the fuel pump are avoided.

The piston of the fuel pump is-in: accordance with the invention advantageously "shaped so I at the top that in part it has a cutting-offedge known per se for cutting on the oil exit to the pressure channel, in part has one or more; preferably'helical, cutting-off edges known per se-for cutting oil at least one oil inlet to theipressure chamber of the pump.

n the accompanying drawing is shown an embodiment of a fuel injection arrangement in accordance with the invention, the figure'showing a vertical central section. throughthe pump andrthe pressure channel of the-latter with. appurtenant control member.

I is the case of the pump and Z a liner. in the: latter. The pump piston 3 is below connected with another piston 4 which can movein a cylinder 5, in the bottom of which there is a channel 6'. Asthe pump works inaccordance with the Archaouloff system, the channel 6 is in communication with the compression space in a motor engine cylinder, so that the pressure from the latter is introduced under the'piston 4. I is'a spring serving for pulling the pistons-3 and 4 downwards through a traverse arrangement, which has only been indicated-by dottedlineson the drawing.

In thecase I or liner '2 of the pump or in both parts there are shaped various channels in communication with the pressure chambers of the fuel pump. 9 is an oil supply channel supplying the oil preferably from a preliminary supply pump, when the piston 3' is in the lowest position shown on the figure. From the channel 9 lead one or-more oil entries It .to the pressure chamber 8. Somewhat higher inthe pressure chamber isan oil exit II to a pressure channel I2, but instead of a. single exit I! there may be several such exits. Outside the case I the pressure channel I2 passes through a slide valve case I3, and on the other side of the. latter it communicates with one or more fuel injection valves, which are not shown. on the drawing, but which are normal automatic and spring-loaded valves. From the pressure channel I2 leads a relief-channel I4 communicating with a return pipe to .the oil tank of the pump, for which relief channel 'the piston 3 forms a slide valve. the channeYM being in a part interruptedby the piston, which at a distance from the top has a clearance I5 ISfor cutting on the oil exit II to the pressure channeLIZ. The top of the pistonhas furthermore been'shape'd so that referably in connec- (iii ti'on withutheedge. It there arexone or more preferably helical. cutting-off edges I! for cuttingoif the oil entry" I0 shownto the rightin the figure, which entry-is the lastto be' closed during the upward movement of the piston. The piston K can be turner, and the degree "of fillingof the pump therebybe regulated, the edge I'l -sooner or later cutting offthe oil entry 10 closed last.

The distance between the cutting-off edge I 6 of'the pump pi'ston for the oil exit II and the upper edge of the clearance I5lin the pump piston is, as the figure shows, equal to the distance between the upper edge of theoil exit II and the upper edge of the entry and exit in the liner 2 or the case I of the relief channel lt.

In the slide valve casing ls the pressure channel l2is controlled by a slide valve I8- with'a clearance I9 The-slide valve is connected with aro'ller holder 20 having a roller 2!. Aispring' 22 or a corresponding member presses the slide valve downwards and thereby the roller 2I ag'ainst a cam disc 23, the cam 24 of which is a so-called negative cam. The cam disc 23 is fitted one. control shaft 25, the aim of which is solely to move the slide valve 58, on which there is practically noload, and" therefore the controlshaft may be Very slender. The control shaft maytin a way known per se be intended for, by turning or shifting, reversing the slide valve motiontcorresponding to ahead and aste'rn working respectively. This reversing may be efiecte'd by a handle on the startin platform, there being normally required no great work for that.

The arrangement shown and described works in the following way.

The pressure in the cylinder is transferred through the channel 5 and will move the piston 3 upwards, so that'thecutwfi edge I! will close the oil entry Into the rightin the drawing. The fuel oil measured. out will thereby be confined in the pressure chamber 8 and in the" pressure channel I2, which is closed by the slide valve I3. The pressure on. this quantity of oil increases while: the compression in the cylinder increases. The cam 24 on the control: shaft '25 is adjusted so that the slide valve I 8- will open the pressure channel I2 at the exact point when the fuel oil injection through the valve orvalves is to be commenced, or rather so much earlier as required by the dead work of the system.

The slide valve I8 thus determines the moment of opening'for the spring-loaded fuel valve 'or valves. The gas pressure will continue moving the piston upwards and press. the oil in through the valve orvalves. When the piston '3- has moved so muchupwards that it cuts off the oil exit II to the pressure channel I2,'the piston is checkedby the quantity of oil confined over the piston-in the "pump case. Coincident with the cutting-off. edge I6 concluding the cutting 'off of the oil exit Ii to the pressure channel the clearance in the piston 3 will begin to-open the relief channel It, so that the pressure chan nel i2 is put in communication with the relief channel I4, which leads to a return pipe to the oil tank of the pump. Consequently thepresin the pressure channel I2 and the valve will be relieved, whereby a sudden closing of the I entry in the liner 2 of the relief channel M the moment for covering the oil exit II in relation to the moment of opening the relief channel M will coincide that is to say the relief channel M will just have been fully opened when the cutting-off edge IE has just completed the closing of the oil exit H to the pressure channel l2, so that the relief of the pressure in the pressure pipe l2 occurs quickly enough for ensuring a good closing of the fuel valve or valves, while at the same time the travel of the piston 3 will not get too large during the time, in which the relief of the pressure takes place. By this means a protection against shocks in the pump is attained.

The spring 22 or the corresponding arrangement, e. g. a weight load, which keeps the roller 2! on the slide valve [8 against the cam 24 on the control shaft ensures.thatif from one cause or another the slide valve should get stuck in the slide valve casing l3the slide valve it will always get stuck in it highest position, so that the oil supply to the valve or valves will be cut off. If the slide valve 18 gets stuck the oil will simply be confined in the pump case, and the ignition in the particular cylinder will then cease, so that the fault will at once be detected and may be remedied. The construction of the control of the slide valve 18 makes it impossible that any considerable irregularities in the working may arise out of a slide valve getting stuck entailing too high ignitions or the like.

As the slide valve it may be fitted at any place in the pressure channel l2 the position of the control shaft 25 may be chosen with due regard to the expediency of the construction and the accessibility of the shaft.

By adjustment of the cam 24 on the control shaft an exact determination of the moment of opening of the valve, i. e. of the moment of ignition may be ensured.

The invention is not limited to the pump arrangement shown and described, as it is not necessary that the control members for the pressure channel l2 and the relief channel is are shaped as slide valves, as these control member or only one of them may consist of a valve or another suitable control member. In the embodiment shown the pump piston 3 forms a slide valve for the relief channel HI, but this may be controlled by another slide valve than the piston 3, contingently by the slide valve 18 which control the pressure channel l2. The measuring of the quantity of oil intended for injection may in the pump be effected in other ways than by a cutting-01f edge ll, preferably helical, situated on the piston, as there may be an independent control member for the particular oil inlet.

I claim:

1. A fuel injection arrangement for internal combustion engines comprising a fuel pump including a cylinder having a pressure chamber therein and a pump piston mounted for reciprocation in the pump cylinder, said pump piston including a large stepped portion, a spring for effecting the suction stroke of the pump piston, a second cylinder, a pipe forming communication between the combustion space of the engine and the second cylinder in which the stepped portion of the pump piston is mounted for reciprocation so that during the pressure stroke the stepped pump piston is driven by thecompressionand combustion-pressure of the engine, at least one fuel inlet to the pressure chamber, at least one cutting-01f edge situated in the pump and disposed obliquely in relation to the axis of the pump piston, which cutting-01f edge in cooperation with said fuel inlet acts for measuring off in the pump the volume of oil intended for being injected into the engine cylinder, a fuel outlet from the pressure chamber, a pressure channel leading from the fuel outlet, at least one automatic, springloaded fuel valve in the engine cylinder and communicating with the pressure channel, a control member inserted in the said pressure channel between the fuel pump and said valve for the timed opening of said pressure channel, a relief channel leading from said pressure channel at a point be tween said control member and the fuel outlet to a return pipe to the oil tank of the pump, and a control member situated in said relief channel for the timed opening of the relief channel.

2. A fuel injection arrangement as claimed in claim 1 wherein the first control member is con stituted by a slide valve provided with a clearance and a roller and said slide valve is operated by a negative cam on a control shaft, the roller being spring pressed against said cam. l

3. A fuel injection arrangement as claimed in claim 1 wherein the second control member is constituted by a clearance formed in the pump piston, said relief channel communicating with the pump cylinder and fluid passage therethrough being controlled by said clearance, said relief channel at the point of communication with the pump cylinder having, in the direction of the'axis of the pump piston, the same extent a the clearance.

4. A fuel injection arrangement for internal combustion engines comprising a fuel pump including a cylinder having a pressure chamber therein and a pump piston mounted for reciprocation in the pump cylinder, said pump piston including a large stepped portion, a spring for effecting the suction stroke of the pump piston, a second cylinder, a pip forming communication between the combustion space of the engine and the second cylinder in which the stepped portion of the pump piston is mounted for reciprocation so that during the pressure stroke the stepped pump piston is driven by the compres'- sion and combustion pressure of the engine, at least one fuel inlet to the pressure chamber, said pump piston having a first cutting-off edg thereon disposed obliquely to its axis, which cutting off edge in cooperation with said fuel inlet acts for measuring off in the pump the volume of oil intended for being injected into the engine cylinder, a fuel outlet from the pressure chamber, said pump piston having a second cutting-off edge formed at its top and disposed in a plane at right angles to its axis, said second cutting-off edge cooperating with said fuel outlet, a pressure channel leading from the fuel outlet, at least one automatic, spring-loaded fuel valve in the engine cylinder and communicating with the pressure channel, a first control member interposed in the said pressure channel between the fuel pump and said spring-loaded fuel valve for the timed opening of said pressure channel, a relief channel leading from said pressure channel at a point between said control member and the fuel outlet to a return pipe to the oil tank ofthe pump, and a second control member formed on said. piston and interposed in said relief channel for the timed opening of the latter. 1 g 5. A fuel injection arrangement as claimed in claim 4 wherein the second control member is r constituted by a clearance formed in the pump 10 piston, said relief channel communicating with the pump cylinder and fluid passage there- EF RENCES CITED h h bemg controlled y said clearamei The following references are of record in the said relief channel at the point of communlcafil of this patent; tion with the pump cylinder having, in the direc- 5 tion of the axis of the pump piston, the same ex- UNITED STATES PATENTS tent as the clearance, the pump piston being ro- Number Name Date tatable for varying the volume of fuel for injec- 1,435,787 Arschaulofi Nov. 14, 1922 tion into the engine cylinder, and the distance 1,995,459 Olsen Mar, 26, 1935 between the second cutting-off edge and the 10 FOREIGN PATENTS clearance in the pump piston being the same as the distance between the edge of the fuel outlet Number Date situated nearest the inner end of the pressure 405,930 Great Brltaln 1934 chamber in the pump and the edge at the point 5501052 Great Blltain 21, 1942 of communication between the relief channel and 15 th pump cylinder situated nearest said end of the pressure chamber,

OVE PETERSEN.

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