DE3228680A1 - Method for the internal combustion of a mixture in a piston-type internal combustion engine, and an internal combustion engine for carrying out the method - Google Patents

Abstract

Published without abstract.

Description

j Dr.-Ing. hero

Lindachallee 9, 7312 Kirchheim / Teck European Patent Office

REPRESENTATIVE BEFORE I

, EUROPEAN PATENT OFRCE

MANDATAIRES PRES L'OFFIC EUROPEEN DES BREVETS

Internal combustion process

Lange Str. 51, D-7000 Stuttgai

a substance mixture in a Tel. (0711) 296310 and 297295

",. j Telex 0722312 (patwod)

Piston combustion engine and telegram address:

Internal combustion engine to carry out tix0722312woiffStuttgart

PA Dr. Brandes: Müncher headquarters

of the process techn. assistance / of couN!

Dipl.-Chem. Dr. Brandes

July 27, 1982 487 375 kws

The invention relates to a method for the internal combustion of a mixture of substances in a piston internal combustion engine, in the course of the filling movement that enlarges the combustion chamber of the piston creates a vacuum in the combustion chamber and this is filled with at least one gaseous component of the mixture of substances, the: M-oi; f mixture counter to this movement set movement - the piston is compressed in the combustion chamber, ignited and expanded for the work performance of the piston and in which process the filling quantity of the gaseous component and / or the amount of a preferably provided as an energy carrier for the mixture of substances liquid or gaseous second component thereof is controlled as a function of the engine power. aside from that the invention relates to an internal combustion engine for carrying out such a method.

In view of the worldwide use of such methods for the operation of internal combustion engines is known Achieving the highest possible degree of efficiency, i.e. the best possible utilization of the energy source

Postscheckamt Stuttgart 7211-700 BLZ 60010070 Telephone information and

Deutsche Bank AG, 14/28630 BLZ 60070070 Orders are only to be sent to schi

Confirmation binding

provided fuel, of paramount economic importance, especially since the resources of suitable energy carriers are limited. It is therefore common practice to design and operate internal combustion engines in such a way that the external engine power loss, i.e. the effort for friction, operation of auxiliary machines, etc., remains as low as possible as well as for to ensure the highest possible thermal efficiency in the combustion process. An improvement in the thermal Efficiency is attempted, for example, by using components that can withstand higher thermal loads to enable safe operation of the engine with less dissipation of thermal energy via the cooling system. Further it is known to increase the thermal efficiency by increasing the compression ratio. A better one One of the reasons why efficiency is achieved is because the particles in the mixture of substances are at a higher compression ratio During the compressive movement of the piston, the piston will be squeezed closer together and become hotter, so that there will be better mixing comes between the first gaseous component and the second component provided as an energy carrier, this especially if it is a liquid energy source whose fuel droplets are further gasified the combustion is faster and more complete. In addition, it has a higher compression ratio relatively smaller compression space has a smaller cooling surface, so that the heat loss through the engine walls the cooling system is correspondingly lower.

The known measures to increase the thermal efficiency are, however, subject to relatively narrow limits.

an attempt is made to dissipate as little heat as possible via the cooling system, so the stability of the motor suffers, even if components that are thermally highly resilient are used operational. There are also limits to increasing the compression ratio. For example, the compression ratio of a gasoline engine limited by the requirement for "knock-free running". With a diesel engine

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there is a corresponding limitation by the requirement after the engine parts are not subjected to excessive stress, the engine is lighter and cheaper and not too rough Run.

The invention is based on the object of a combustion method of the type in question, if it is applied, one that can be achieved using the usual procedures far-reaching additional improvement in efficiency can be achieved.

In a method of the type mentioned at the outset, this object is achieved according to the invention in that additional measures be taken to the filling amount of the gaseous first constituent of the mixture of substances regardless of the Significantly lower power control. This process is based on the general idea, the combustion process to be designed in such a way that the burning substance mixture is expanded far more completely within the combustion chamber than is possible with the usual procedures. The fact that according to the invention worked with an extremely low filling there is a larger amount within the combustion chamber in relation to the filling quantity, i.e. the volume of the filling Expansion volume (which corresponds to the displacement volume) is available, i.e. the possibility is created that the burning substance mixture can expand more strongly 5 during the task. The lowering of the filling quantity, i.e. the Increasing the expansion or displacement volume compared to the filling volume, caused due to the better utilized Expansion a more complete energy conversion within the system. The energy content of the more relaxed and therefore cooler exhaust gas is less than with the usual method. Not only does this result in less heat dissipation due to the reduced exhaust gas temperature, but there is also less work for the piston due to the Expend ejecting the exhaust gas, since due to the complete relaxation a lower gas back pressure or exhaust gas

There is residual pressure, "which will be overcome during ejection got to. In addition, the exhaust noise is significant due to the large expansion of the gases prior to exhaust reduced.

The additional measures to the desired filling volume independently to reduce the power control can consist in the fact that the filling movement enlarging the combustion chamber of the piston an additional negative pressure is generated, which is essentially limited to the combustion chamber. Measures are therefore taken to prevent the flow of the gaseous component into the combustion chamber, these measures, in order to limit the additional negative pressure only to the combustion chamber, directly in the area of the Inlet opening of the same can be used. Accordingly, these are measures that differ from the usually provided for power control, influencing the filling quantity, for example, by a throttle effect Measures, such as throttle valves of carburetors or injection systems, which are on the gas paths at a greater distance of the inlet opening of the combustion chamber are arranged, differentiate. In the method according to the invention, the fill quantity reducing, additional negative pressure in the combustion chamber can be generated by closing a shut-off device in the area the inlet port is arranged. In the case of an engine with control organs for controlling the gas exchange, in particular a four-stroke engine, that takes place in terms of working cycles the inlet valve assigned to the inlet opening can be used as a shut-off device to generate the additional negative pressure, by controlling the intake valve to remain open during a substantial portion of the combustion chamber enlarging fill movement of the piston is kept closed.

Instead of one provided in the area of the inlet opening Shut-off device, for example an inlet valve, can

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Negative pressure also through a throttle device arranged in the gas duct close to the inlet opening of the combustion chamber be generated. A controllable throttle device can be used, the throttling effect of which, for example is controlled depending on the speed. The use of a shut-off device, for example an inlet valve, to generate of the additional, the filling amount during the filling movement of the piston limiting negative pressure has compared to a Inlet throttle has the advantage that the movement of the piston against the piston, which increases the size of the combustion chamber, is produced Vacuum work to be done in the subsequent compressive movement of the piston essentially is recovered because when the shut-off device is closed, the negative pressure in the combustion chamber during the compressing movement of the piston acts as a driving force until this previously built up negative pressure in the course of the compressing piston movement is dismantled again.

Instead of creating an additional negative pressure in the combustion chamber during the filling movement of the piston, it can be used to reduce it the filling quantity can be proceeded in such a way that a part of the gaseous first constituent, e.g. air, during the compressive movement of the piston is blown out of the combustion chamber. When working on the four-stroke principle Otto injection engines or diesel engines, the blowing off 5 of the air can be done via the outlet valve, which during the compressive movement of the piston is opened for a suitable period of time and then closed again before the fuel is injected. In the case of two-stroke injection engines, an additional blow-off valve can be used for this purpose Find use.

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It should be noted as essential that the measures for limiting the filling quantity provided in the method according to the invention can be used together with the previously customary measures to improve efficiency. For example in addition, an improvement in the thermal efficiency by using more thermally more resilient Components can be achieved. The principle of efficiency improvement is also through the highest possible compression easily feasible by choosing the size of the compression space relative to the displacement volume so that that in the case of the reduced filling provided according to the invention, the desired final compression pressure is obtained. It can be seen that the combustion chamber filling, which is reduced in the method according to the invention, in itself results in a reduction in performance of the internal combustion engine means. Because of the greatly increased efficiency of the process However, this performance loss is not particularly blatant and can easily be compensated for by increasing the displacement will.

A reciprocating internal combustion engine suitable for carrying out the method with a device provided for controlling the engine output for influencing the filling quantity of the gaseous The first component of the mixture of substances that can be fed to the combustion chamber during the filling movement of the piston is according to the invention by means of a limiter device which significantly reduces the filling quantity independently of the power control marked.

The invention is explained in detail below with reference to the exemplary embodiments shown in the drawing.

Show it:

Figs. 1 and 2 are diagrams of the work

game of a four-stroke combustion process according to the prior art or according to an embodiment of the method according to the invention;

Fig. 3 is a ver in the region of the inlet valve

running, highly schematically simplified drawn vertical section of a four-stroke gasoline engine for the application of the method according to the invention;

FIG. 4 shows a section similar to FIG. 3

Four-stroke gasoline engine for implementing a modified embodiment of the procedure and

5 shows a very schematically simplified vertical section of a pair

stroke gasoline engine for gasoline injection, which is used to carry out an exemplary embodiment of the method according to the invention is provided.

5 Figs. 1 and 2 show a crankshaft 11 of a four-stroke internal combustion engine, the crank 6 of which is connected to the piston 15 of a cylinder 8 by a connecting rod 7 and rotates in the direction of arrow 13 during operation of the engine. The cylinder 8 has an intake valve 19 and an outlet valve 20, different from those not shown Cam of a valve intended for valve control,

camshaft also not shown, which during of operation, are opened against the force of valve springs, not shown in FIGS. 1 and 2.

The angular positions of the crank 6 are indicated on a spiral line 17. Here are those of the crank during of the approximately twice rotation in the direction of arrow 13 successively assumed positions indicated as follows:

Eö opening of the inlet valve 19 OT top dead center of the piston 15 UT bottom dead center of the piston 15 ES closing of the inlet valve 19 ZZ ignition of the compressed gas mixture in cylinder 8
AÖ open the outlet valve 20 AS close the outlet valve 20.

The work cycle begins with the crank position marked EÖ with the opening of the inlet valve 19. With the outlet valve 20 closed, the following rotary movement of the crankshaft 11 in the direction of arrow 13 when the piston 15 has passed the top piston dead center OT moved downwards, a quantity of gas is supplied to the combustion chamber 21 via the open inlet valve 19. at the usual method shown in Fig. 1, the inlet valve 19 remains open until the rotary position ES of the crank 6 from 35 ° to 45 after bottom dead center UT is reached. With the inlet valve 19 and outlet valve now closed 20, the movement of the piston 15 compresses the contents of the combustion chamber and shortly before reaching the upper one Ignited dead center at ignition position ZZ. During the subsequent working stroke, in the course of which the Piston 15 from top dead center OT to bottom dead center Moved towards BDC, both valves 19 and 20 are closed until

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the outlet valve 20 opens about 45 ° before reaching the bottom dead center UT in the position Aö. The exhaust valve 20 remains open for the subsequent expulsion of the burnt contents of the combustion chamber 21 until the Piston 15 has again exceeded top dead center OT and the crank position AS is reached. The usual The control times of the valves 19 and 20 applied to the method, as shown in FIG. 1, are for example from "Lueger", Lexikon der Technik, 4th ed., Vol. 7, page 517, to be found. Fig. 1 shows the piston 15 during the filling movement, wherein the crank 6 has a rotational position of about 120 ° after TDC. As indicated by a dashed line 23 is, this position is approximately in the middle between the open position EÖ and the closed position ES of the inlet valve 19, so that the filling process continues with the further movement of the piston 15 to bottom dead center UT and the best possible filling of the combustion chamber 21, which is aimed for in the known method, occurs.

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The method according to the invention differs from the conventional method Method, as already mentioned, in that the combustion chamber 21 is filled with a reduced amount. Fig. 2 shows an embodiment of the method according to the invention, in which the reduction in the filling quantity what is achieved is that the inlet valve 19, which is used for the filling process in the example shown, is at the same crank position Eö as with the conventional method is opened, is closed much earlier than with the conventional method Procedure. As can be seen from FIG. 2, the closing point designated ES is approximately 60 after top dead center OT. In the rotational position of the crank 6 shown in FIG. 2, the closing point ES is as indicated by the dashed line Line 23 is illustrated, has already been exceeded, i.e. the inlet valve 19 is already closed, so that there is no increase in the movement of the piston 15 in the combustion chamber 21 towards the bottom dead center BDC the filling quantity, but only an additional negative pressure is generated. This negative pressure pulls after being exceeded the bottom dead center BDC the piston 15 upwards, i.e., the work expended to generate the additional negative pressure from the piston 15, apart from the losses, recovered at the start of the compressive stroke. The compressing one The stroke of the piston 15 therefore initially begins with the reduction of the previously prevailing additional negative pressure and subsequent build-up of the compression pressure. The volume of the compression chamber of the combustion chamber 21 is in proportion chosen for the displacement volume so that, although the compressing stroke is started with negative pressure, when it is reached the desired compression end pressure is reached after top dead center OT. As with the traditional procedure, takes place briefly before reaching top dead center OT the ignition at the ignition point marked ZZ. During the subsequent incineration there is, since a filling quantity that is substantially reduced in relation to the cubic capacity volume is burned, to a large extent

already within the combustion chamber 21 stronger expansion / and thus a much improved one Energy utilization compared to the known method. Since the more relaxed exhaust gas after combustion in the invention Process can be ejected more easily, the opening point Aö in certain cases for the outlet valve method according to the invention are closer to bottom dead center UT than at the known method. The most suitable valve control times for the respective application can be found in the method according to the invention as with the usual procedures, through experiments, exactly how they are usually carried out for engine optimization.

Instead of creating the additional negative pressure at the end of the filling stroke, as shown in Fig. 2, where the inlet valve opened in the area of top dead center OT and closed long before bottom dead center BDC was reached the additional negative pressure could be generated by delayed opening of the inlet valve 19. It can te also any section between top dead center OT and bottom dead center UT as compared to the prior art Shortened opening area of the inlet valve 19 can be provided if tests show that a certain, between the area lying at the points OT and UT is particularly advantageous for a relevant engine.

Fig. 3 shows a four-stroke Otto engine, in which the substance 5 mixture in the combustion chamber 21 by means of a spark plug 31 for the Combustion is ignited. Only one intake cam 33 assigned to the intake valve 19 is borrowed from the valve control shown, which is arranged on a camshaft rotating in the usual way at half the speed of the crankshaft 11 is. In the example shown in FIG. 3, the reduced filling of the combustion chamber 21 is, as in the example of Fig. 2, generated by opening the inlet valve 19 only briefly during the filling stroke. To this

For this purpose, the cam 33 is provided with a relatively pointed cam profile 35, which in the case of the arrow 13 specified direction of rotation of the crankshaft 11 and the with an arrow 37 indicated direction of rotation of the cam 33, the valve end 39 in the indicated rotational position of the Crank 6 has already released from 90 ° after TDC, so that the inlet valve 19 by the action of its valve spring 41 is already closed again in this position. With the further filling stroke of the piston 15 in the combustion chamber 21 so the additional negative pressure is generated in the desired manner.

Fig. 3 shows with a dash-dotted line as an alternative measure, which in the combustion chamber 21 during the filling movement of the Piston 15 generates the additional negative pressure, a constriction 43 provided at the inlet opening, which acts as a throttle device During the filling stroke of the piston 15, a filling-reducing negative pressure is generated, even when the inlet valve 19 is open. In this modified exemplary embodiment, indicated by a dash-dotted line, it is therefore also possible with the in Fig. 1, the usual control times shown, the additional negative pressure worked exclusively through the throttling effect the constriction 43 are generated. Instead of the pointed profile of the cam 33 denoted by 35, accordingly to control the inlet valve 19, a normal cam with a conventional profile is used.

FIG. 4 shows an exemplary embodiment which in principle corresponds to the exemplary embodiment indicated in FIG. 3 with a dashed line is equivalent to. The additional negative pressure in the combustion chamber 21, which reduces the filling quantity, is therefore not determined by choice the corresponding valve timing of the inlet valve 19 is achieved, but by an additional throttle device in the form of a throttle valve 45 which is arranged in the region of the inlet opening of the combustion chamber 21, so that the additional negative pressure essentially generated during the filling stroke

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limited to the area of the combustion chamber 21. By moving the throttle valve 45 in the direction of its valve stem, the size of the opening can be adjusted, ie the throttling effect can be controlled. The size of the additional negative pressure, and thus the filling quantity limitation _, can thus be set to the desired value and, if necessary, optimized as a function of the speed. In all embodiments in which the additional negative pressure is made not by choosing the timing of the inlet valve 19, but by a throttle device at the inlet port, a normal inlet cam 47 with a customary cam profile can be used instead of the pointed cam 33 of FIG.

The throttle valve shown in Fig. 4 as a poppet valve 45 could be replaced by a rotary valve or a similar controllable shut-off device. Alternatively it could be as Throttle device can also be provided for the intake valve 19 itself by using an intake cam which is only a very small one exposing a limited inlet opening Valve lift generated, which has a corresponding throttling effect.

In internal combustion engines, where pure air is used when compressing Stroke is compressed and the fuel serving as an energy carrier is injected into the compressed air, i.e. with two-stroke or four-stroke gasoline engines with direct fuel injection into the combustion chamber, as well as two-stroke and four-stroke diesel engines, can be used as a measure To limit the filling quantity, some of the air is blown out of the combustion chamber 21 during the compressing stroke of the piston will. Fig. 5 shows an embodiment of a two-stroke Otto engine for direct fuel injection into the Combustion chamber 21 by means of an injection nozzle 51. A rotary slide 53 is provided as a blow-off valve, its rotary position Can be controlled by the crankshaft 11 in terms of the work cycle. The rotary valve 53 opens with a blow-off slot 55

into the combustion chamber 21 at a point above the mouth of the overflow channel 57 (inlet slots and outlet slots are not shown in Fig. 5) is located. During part of the compressive stroke of the piston 15, the slot 55 is released by the piston 15, so that when the rotary valve 53 is open, air is blown off. before Approaching the piston 15 to the top dead center, the slot 55 is closed by the piston, so that the remaining Air in the combustion chamber 21 is compressed during the remaining part of the piston movement. In the compressed air is then fuel is injected through the nozzle 51 and ignited by the spark plug 31. Since the closing of the vent slot 55 is controlled by the piston itself, the setting of the closing time for the rotary valve 53 itself needs to be set not to be given special attention.

In fuel-free air-compressing engines with a controlled Exhaust valve, i.e. in four-stroke Otto injection engines or four-stroke diesel engines, can be the exhaust valve itself be provided as a relief valve which is opened during part of the compressive stroke. In such Embodiments is the exhaust cam of the valve control with a second profile, one of the profile 3 5 of the inlet cam 33 of Fig. 3 has a similar pointed shape, provided around the exhaust valve during the compressive stroke to open relatively briefly so that just enough air is blown off that the desired reduction in Filling level is reached. Otherwise, the same timing can be used as with the usual procedures, Thus, for example, the control time shown in Fig. 1, with only during the compressive stroke between the lower piston dead center UT and the upper dead center OT the exhaust valve 20 is additionally opened and closed again will.

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Claims (23)

Claims The invention relates to a method for the internal combustion of a mixture of substances in a piston internal combustion engine, in which a negative pressure is generated in the combustion chamber during a filling movement of the piston that enlarges the combustion chamber and filled with at least one gaseous component of the mixture of substances, the mixture of substances in one of these Movement opposite movement of the piston in the combustion chamber is compressed, ignited and expanded for the work performance of the piston and in which process the filling amount of the gaseous component and / or the amount of a liquid or gaseous second component of the same, which is preferably provided as an energy carrier for the mixture of substances, depending on the Engine power is controlled, characterized in that additional measures are taken to significantly reduce the filling amount of the gaseous first constituent of the mixture of substances independently of the power control. 2. The method according to claim 1, characterized characterized in that measures are taken through which an additional negative pressure during the filling movement of the piston is generated, which is essentially limited to the combustion chamber. 3. The method according to claim 1 or 2, characterized in that an additional negative pressure reducing the filling is generated by closing a shut-off device which is arranged in the region of the inlet opening through which the gaseous first component enters the combustion chamber. 4. The method according to claim 3, characterized in that in the case of an engine with control elements for controlling the gas exchange according to the work cycle, that of the inlet opening assigned control element as a shut-off device for generating the additional negative pressure is used. 5. The method according to claim 4, characterized in that in an engine with a controllable inlet valve this for generating the additional negative pressure during a considerable part of the filling movement of the piston in the closed position closing the inlet opening is held. 6. The method according to claim 5, characterized in that in a reciprocating engine, the inlet valve for the filling stroke long before the end of the filling stroke is reached assigned lower piston dead center is closed. 7. The method according to claim 5, characterized in that in a reciprocating engine, the inlet valve only well after the top dead center of the piston associated with the beginning of the filling stroke is opened. 8. The method according to claim 6 or 7, characterized in that the inlet valve at a rotation angle of the crankshaft of less than η · 10 ° after the top dead center associated with the beginning of the filling stroke of the piston where η is one of the integers from one to seventeen. 9. The method according to claim 8, characterized in that the inlet valve at a rotation angle of the crankshaft of less than 120 after top dead center, preferably from less than 90 ° after top dead center, is closed. 10. The method according to claim 2, characterized in that the additional negative pressure by a close in the gas guide Throttle device arranged in front of the inlet opening of the combustion chamber is produced. 11. The method according to claim 10, characterized in that a controllable throttle device is used and its Throttle effect is preferably controlled as a function of the speed. 12. The method according to claim 1, characterized in that that in a reciprocating engine, in which air is compressed as a gaseous first component of the mixture of substances in the combustion chamber, as an additional measure to reduce the
Filling quantity some of the air is blown out of the combustion chamber during the compressing movement of the piston. 13. Piston internal combustion engine for performing the method according to one of claims 1 to 12 with a device provided for controlling the engine output
Influencing the filling amount of the gaseous first constituent of the mixture of substances during the filling movement of the piston can be fed to the combustion chamber
by means of a limiter device which significantly reduces the filling quantity independently of the power control. 14. Motor according to claim 13, characterized in that as a limiter device during the filling movement of the KoI-ben (15) an additional negative pressure in the combustion chamber (21)
generating device is provided. 15. Motor according to claim 14, characterized in that the limiter device has a controllable shut-off element arranged in the region of the inlet opening of the combustion chamber (21) which can be moved into the closed position during a substantial part of the filling movement of the piston (15) is. 16. Motor according to claim 15, characterized in that in the case of an engine with an inlet valve which is used to control the gas exchange and can be actuated by means of a valve control valve (19) this as a shut-off device to generate the additional Negative pressures are provided and controlled by the valve control during a substantial part of the filling movement of the piston (15) can be controlled into the closed position. 17. Motor according to claim 13, characterized in that the limiter device has a throttle device (43, 45) in which the supply of the gaseous first component serving suction pipe, the inlet opening is arranged closely adjacent. 18. Motor according to claim 17, characterized in that a controllable throttle device in the form of a throttle valve (45), a rotary valve or a throttle valve is provided. 19. Motor according to claim 18, characterized in that in the case of an engine with an inlet valve which is used to control the gas exchange and can be actuated by a valve control (19) this is provided as a throttle device and, by virtue of the valve control, with only little, preferably speed-dependent variable opening stroke is actuated. 20. Motor according to claim 13, characterized in that in the case of an engine in which air is compressed as a gaseous first component of the mixture of substances in the combustion chamber (21) is, a blow-off of air from the combustion chamber (21) during the compressive movement of the piston (15) possible Limiter device is provided. 21. Motor according to claim 20 ,. characterized in that in an engine with one for controlling the gas exchange serving, actuated by means of a valve control outlet valve (20) this as a limiting device for blowing off compressed air is provided and controlled by the valve control during part of the compressive movement of the piston (15) can be moved into the open position. 22. Engine according to claim 20, characterized in that in a two-stroke reciprocating engine a controllable working cycle Blow-off valve (53) is present, through which air can be blown out during the compressing stroke of the piston (15) is. 23. Engine according to claim 22, characterized in that the blow-off valve (53) in the combustion chamber (21) with one from Piston (15) traversable slot opening (55) opens which is arranged so that it from the piston (15) in the course of the compressing Stroke is closed before reaching the top piston dead center (TDC).