WO2016016194A1

WO2016016194A1 - Control of the variable compression ratio of a reciprocating piston internal combustion engine

Info

Publication number: WO2016016194A1
Application number: PCT/EP2015/067169
Authority: WO
Inventors: Bastian Holderbaum; Thorsten Schnorbus; Matthias Thewes
Original assignee: Fev Gmbh
Priority date: 2014-07-29
Filing date: 2015-07-27
Publication date: 2016-02-04
Also published as: DE112015003493A5

Abstract

The present invention relates to a method for operating a reciprocating piston internal combustion engine with an adjustment of an effective length of a connecting rod 17 of a cylinder, wherein the compression ratio that is adjustable therewith is changed at least during the operation of the reciprocating piston internal combustion engine and is adapted to at least one further engine component. Disclosed is also a VCR reciprocating piston internal combustion engine having an adjustable compression ratio, wherein one or more methods, as proposed, are implemented. The invention also relates to program code means for implementation in a control device, preferably an engine control device of a VCR reciprocating piston internal combustion engine; wherein the program code means implement during their use one or more methods, as proposed.

Description

CONTROL OF THE VARIABLE COMPACTION RATIO OF A PISTON INCINERATION ENGINE

The present patent application claims the priority of German Patent Application 10 2014 010 974.7 of 29 July 2014, the content of which is hereby incorporated by reference into the subject matter of the present patent application.

The invention relates to a method for operating a reciprocating internal combustion engine with VCR (Variable Compression Rate), a VCR reciprocating internal combustion engine and computer program means therefor. VCR reciprocating internal combustion engines are advantageous because the compression ratio, i. H . the can be changed in the top dead center of the piston adjusting distance to the cylinder head. DE-A-10 2005 055 199 discloses a VCR adjusting mechanism which has a piston pin adjustment with hydraulic support on the upper connecting rod bearing. As a result, the effective length of the connecting rod can be set differently depending on the requirement.

A reciprocating piston engine in the form of an internal combustion engine with a map-controlled, variable compression ratio is known from DE-A-10 2004 031 288. This document teaches to set the compression ratio, in particular by an optimization strategy, by means of operating conditions such. B. a uniform combustion and the like should be improved. Embodiments of a reciprocating engine, in particular an internal combustion engine with a variable compression ratio are described in the patent applications DE-A-102 55 299, DE-A-198 41 381 and in DE-C-37 35 914. DE-A-102 55 299 describes z. B. a connecting rod with variable effective Connecting rod length to change the Verdichtungsverhältnisses a Hubkol ben ^¬ machine. H ierbei is changed to the connecting rod by means of a connecting rod mounted on the eccentric of the Ab ^¬ stand of the piston. DE-A-198 41 381 describes an eccentric on a crank, whereby by means of the eccentric of the crank wheel and thus the compression ratio can be changed. Furthermore, from DE-C-37 35 914 a device for Verstel len of the Zyl indderkopfes an internal combustion engine to change the compression ratio.

The object of the present invention is to further improve the operation of a reciprocating internal combustion engine with an adjustable compression ratio.

This object is achieved with a method having the features of claims 1 and 16, with a VCR reciprocating internal combustion engine having the features of claim 19 and with program code means for implementation in a control unit with the features of claim 20. Further advantageous embodiments and further developments go from the following U nteransprüchen as well as from the following Beschreibu ng forth. Individual features of individual embodiments can also be linked to one another as well as different subsequent configurations can be linked to one another. In particular, the respective independent claims should not be construed as limiting the particular subject matter of the invention. For better specification, one or more features can be respectively supplemented but also omitted or replaced in order to define the invention more closely.

A method of operating a reciprocating internal combustion engine with a VCR, preferably proposed d urch change the effective length of a connecting rod ei ^¬ nes cylinder, the Dilute ichtungsverhältnis at least during operation of the H ubkol benverbrenn ungskraftmasch ine changed and thereby coordinated with at least one other motor component is ,

By tuning with another engine component manages the Change in the compression ratio not only z. B. of at least a first desired operating parameters such. B. the load request to the Hubkol- benbrennkraftmaschine by the operator or driver to make dependent. Rather, this load request as well as z. For example, a current operating point can be included in a strategy for setting the variable compression. In addition, but now also the respective operating behavior of z. As exhaust gas cleaning components or other engine components considered. The change in the compression ratio can according to an embodiment of the invention fully variable ie continuously. A further embodiment of the invention provides that the compression ratio can be changed in discrete steps. Another embodiment of the invention provides z. For example, a fully variable adjustment of the compression ratio is given in a first range, whereas in a second range only a change of the compression ratio in discrete steps is possible.

According to one embodiment of the invention, it is provided, for example, that the adjustment of a first to a second compression ratio is determined and implemented in a field-based and / or model-based manner. Thus, according to one embodiment of the invention, it may be provided that an engine component itself is model-based. Also, for example, the behavior of an engine component, for. B. an emission control component can be mapped in different operating points. Thus, the respective, to be taken into account in the adjustment of the compression ratio operating behavior of one or more engine components to increase or decrease the compression ratio and / or a change in the switching threshold lead, depending on the size of the z. B. load request the compression ratio is changed.

An embodiment of the invention provides that a map-based and / or model-based switching as a function of the operating state of an exhaust gas recirculation, abbreviated EGR takes place. In this case, not only an external EGR, in particular not just a cooled EGR can be taken into account. Rather, an internal EGR can also be taken into account. One possibility, for example, is to provide a procedure with regard to a model-based cylinder charge detection for an internal combustion engine. For this purpose, reference is made by way of example to the content of DE-A-10 2014000 397. From this shows how z. B. can also enter an internal EGR in the context of modeling, this model formation in the VCR adjustment z. B. can be used according to the invention. The content of this document is hereby incorporated by reference into the subject of the present application.

Another embodiment of the invention provides z. Example, that an external exhaust gas recirculation is performed, a parameter characterizing this exhaust gas recirculation is determined and evaluated by a control unit, wherein by means of the external exhaust gas recirculation cooling of the fuel-air mixture in the cylinder takes place, with the increase in load request an increase a compression is also accompanied by a shift of the switching point from higher to lower compression in a characteristic field.

It can also be provided according to the invention or a further development that an external EGR cooling miteingeht. So z. B. allow the use of an external EGR cooling higher compression, which again in the map or in the model, a switching point for changing the compression ratio can be moved, especially towards a larger load request. The exhaust gas recirculation rate is preferably determined via the lambda probe or via a model formation. Furthermore, it can be provided in a variant of the invention that for starting the Hubkolbenverbrennungskraftmaschine to produce a faster ^¬ ren heating a catalyst or other Abgasbehandlungskom- component, a lower compression is set, wherein upon reaching a minimum temperature of the exhaust gas treatment component, the compression is increased when this z. B. is indicated by the load request. In this way, z. For example, the proportion of HC can be kept low, as well as the generation of NOx. The reduction of the compression is z. B. limited by the fact that an impact of an injection in the cylinder should not impinge on the piston directly.

It can also be provided in a further development of the invention that the switching threshold takes place with respect to the initiation of the compression change with cooling EGR. As shown, for. B. in a working on the diesel principle VCR reciprocating internal combustion engine in a heating phase no EGR be made and kept the compression ratio low or possibly even lowered directly after the start. Furthermore, there is the possibility that a reduction of the set compression ratio z. B. for desulfation at z. B. a NOx storage catalyst is made. There is also the possibility that in a rich operation with a variable compression ratio of the operation is made, for. B. to cushion NOx spikes. So z. For example, in the case of a prediction of excessively high NOx values, the compression is lowered, thereby avoiding excessive NOx production. There is also the possibility that in the model or in the respective map additionally a water injection can be considered in the intake tract. The injection of water can be carried out in order to achieve a further reduction of NOx values, in particular if further reduction of the compression ratio is not possible or will not have the desired effect.

Furthermore, for example, provided that a deliberate deterioration of an efficiency is accepted, for. In relation to a particulate filter reactor. A further embodiment of the method according to the invention provides that when switching between different maps, which are assigned to different densities, the target torque is kept the same, and preferably such that in a spark-ignition internal combustion engine setting a higher compression is accompanied with a shift of at least one injection toward late or in a self-igniting reciprocating internal combustion engine, a setting of a lower compression is accompanied by a shift of at least one injection in the direction early in the map is switched to.

The method preferably has different parameters as desired values. It is preferred that the desired value for the boost pressure, the target value for the injection pressure and the target value for an exhaust gas recirculation also be subject to an adaptation when switching from a first to a second map.

Furthermore, it can be provided that one or more switching thresholds for switching from one characteristic map of an engine control system to another engine control system control map are changed in the event of a change in the compression ratio.

For example, it may be provided that a cylinder deactivation is provided with a change in the compression ratio of a fired cylinder, wherein the switching threshold is changed from one map to another map in the fired cylinder for adaptation to a modified optimum effect.

Furthermore, it can be provided that the compression ratio of a non-fired cylinder is reduced with the cylinder deactivation.

It may also be provided that a compression ratio of a non-firing erten cylinder is increased with the cylinder deactivation.

One embodiment sees z. Example, before that one or two cylinders are turned off. So z. For example, in a 3-cylinder VCR reciprocating internal combustion engine, a single cylinder may be shut down, whereas, for example, a single cylinder may be shut off. B. in a 4-cylinder VCR reciprocating internal combustion engine, two cylinders are switched off ^¬ . This can lead to a shift of an optimum effect, so that conditionally, for example, a changeover ^threshold for changing the compression in at least one of the two fired cylinders is changed. Preferably, a correlation between the inner cylinder pressure and the compression ratio to be set is used. An embodiment provides, for example, that a deactivated cylinder is set to a lower compression ratio, in particular by z. B. minimize wall losses. There is also the possibility that the compression ratio is increased in one of the non-fired cylinders. For example, this may influence the vibration behavior of the system. Preferably, the compression ratio is changed in two non-fired cylinders, in particular changed differently, that as a function of speed and load, a swing in the system is avoided. For this purpose, z. B. at least one flow sensor are used, the z. B. can absorb the speed of a passing fluid. A pressure sensor can also be used.

A further embodiment of the invention provides that a change in the compression ratio is used for peak pressure control. Thus, it can be provided in a regulation of the peak pressure that at a high load, the compression ratio is lowered, which allows to reduce the peak pressure from ^¬ . For such a control, a pressure sensor is preferably assigned to each cylinder. A change in the compression ratio can z. B. be determined with a combustion chamber pressure model.

It can also be provided that the change in the compression ratio is used for knock control.

A further embodiment of the method provides that the quality, in particular the ignitability of the fuel is determined, wherein an adaptation of a map in dependence on the determined fuel quality, wherein the switching threshold is changed for switching from one compression ratio to another compression ratio. Preferably, therefore, the fuel quality determines the switching point for changing the compression ratio.

Again, it may be provided that an ignition timing change is made via a change in the compression ratio, wherein the ignition timing change is preferably effective at least in the next cycle after changing the compression ratio.

In particular, however, the method in connection with this procedure can also provide for a changeover threshold change with respect to a change in the compression ratio in the case of a water injection.

For a water injection is preferably provided that condensate is used by a heat exchanger and / or air conditioning for water injection. For example, a tank may be provided in which the condensate is collected and can be injected if necessary. Also, the tank z. B. be accessible from the outside and be filled from the outside with a suitable liquid. For example, a model may be implemented that is capable of taking into account the amount of condensate produced and / or used that has been injected. A further preferred exemplary embodiment of the invention provides for the operating state of an exhaust gas recirculation system and / or an exhaust aftertreatment system to be taken into account for the adjustment of the compression ratio. is considered.

A development of the invention provides that if the exhaust gas recirculation system and / or the exhaust aftertreatment system is not yet operational due to low temperatures, the compression ratio is adjusted so that lowest raw emissions are formed, whereas preferably at a sufficient temperature, in particular optimum operating conditions of Exhaust after-treatment system, the compression ratio is preferably adjusted towards a lower fuel consumption.

For example, a model of a NOX storage catalytic converter can be included in the adjustment of the compression ratio. Its efficiency may depend on different operating parameters. In particular, its temperature dependence can thus be detected and aligned with it, the compression ratio of at least one or more, but also all cylinders can be adjusted. In a diesel engine can, for. B. as long as an SCR catalyst does not work, which z. B. in a heating phase is the case, the compression ratio can be lowered. Furthermore, there is the possibility that the fuel consumption or the consumption of additives such as AdBlue can be included in a model calculation with regard to the compression ratio to be set. It can also be provided that z. B. with regard to a filling of an ammonia storage for this, the compression ratio is lowered.

According to a further consideration, the consideration allows z. B. the ambient temperature of the respective dew point, the humidity curve, but also the temperature of components such as the EGR, the one or more catalysts, storage, compressors targeted adjustment of the compression ratio, either a lowering or increasing the compression ratio provide, for. B. to prevent the formation of condensate, which otherwise z. B. could cause damage, z. B. by Drop impact in a compressor. That compression ratio is z. B. then increased again when the risk of unwanted condensation is no longer present, especially if at least one temperature has been reached, the z. B. allows the evaporation of condensate. An embodiment sees z. Example, that for the time for which an external EGR is not yet activated (because, for example, the risk of dew point undershooting with concomitant condensation formation exists), the compression ratio is increased or remains high. If an oxidation catalytic converter has reached its operating temperature, it is possible to switch to a lower compression ratio. It then eventually comes to the formation of more HC, CO, but then can be processed by the oxidation catalyst.

A development of the invention provides that for a first period in which an external exhaust gas recirculation is not yet carried out, in particular for the period to lower temperature of an exhaust gas purification system, the compression ratio is high, however, with reaching a sufficient temperature of the exhaust gas purification system, the compression ratio is ^¬ lowered. According to a further aspect of the invention, it is provided that a plurality of cylinders of the reciprocating internal combustion engine are switched to one another differently with respect to their respective compression ratios, preferably for use of one of the cylinders as a compressor or expansion cylinder in an exhaust heat utilization system.

Another idea of the invention provides z. B. before that a mode changeover, preferably from a HCCI operation in a SI operation or ^vice versa, accompanied by a change in the compression ratio, wherein before the mode changeover, the compression ratio lowered and after the mode changeover, the compression ratio again he ^¬ increases becomes. In this way, z. B. the high temperatures of the exhaust gases and thus a risk of knocking be taken into account, the z. B. can be mapped in a model or a map

Furthermore, it can be provided that in addition to a cylinder deactivation and other components, z. As regenerators for energy recovery, or a start-stop system. Thus, a distinction can be made via a map or a model, whether a vehicle holds only short term or has been turned off for a long time. Depending on this, z. B. the respective compression ratio can be adjusted. Thus, according to one embodiment, provision may be made for preheating after parking the vehicle. For this purpose, the compression ratio is lowered. Also, when the vehicle is turned off, an afterglow may be provided. Here, the temperature z. B. enter the environment. If this example, not less than a limit, for. B. -20 ° C, the compression ratio is lowered. However, if the temperature, in particular the ambient temperature lower, the compression ratio is increased. In addition, a variable valve train can be modeled and taken into account as well as in the other circumstances. The vehicle can z. B. provide a system that has stored enough energy, so that the compression ratio can be changed even after parking the vehicle. This is possible, for example, with an oil pressure accumulator. As a result, z. B. can be safely distinguished between a start-stop situation and a parking of the vehicle.

According to a further aspect of the invention, a VCR Hubkolbenverbrennungskraftmaschine is proposed with an adjustable compression ^¬ relationship, wherein one or more of the above are implemented as well as methods described in more below. The VCR reciprocating internal combustion engine may, for. B. as described at the beginning in the prior art, be constructed, for. B. with support cylinders, via which a Verstellgestänge is supported for an eccentric. Preferably, two first control lines each open into the bottom of the respective support cylinder, so that a medium in the as well as from the support cylinder on this Can flow in and outflow. For this purpose, the VCR piston engine can be designed, for example, as described, for example, in DE-A-10 2005055 199, DE-A-10 2011 056298, DE-A-10 2012014917, DE-A-10201110890, DE-A- 10 2010 061 360, DE-A-10 2010 061 359, DE-A-10 2010 061 361 and / or DE-A-10 2008 005 467, referred to in the context of the disclosure with regard to the possible construction of the connecting rod with eccentric adjustment the compression piston, the adjusting mechanism and the support ^¬ cylinder or support piston and their operation is pointed out and the contents of which belong to the subject of the present patent application.

A further embodiment of the invention provides that the VCR piston engine has a switch which is in communication with a second control line of the support cylinder, wherein the second control line is opened or closed by means of the switch. This switch is preferably a constituent part of the adjusting mechanism and is particularly preferably arranged on or in the connecting rod. According to one embodiment, the switch is able to allow or prevent the inflow or outflow of the medium, in particular oil of Kolbenma ^¬ machine, in or out of the respective support cylinder. Preferably, a multi-way valve is used as a switch, over which z. B. simultaneously several control lines can be switched. The valve system may comprise, for example, a 3/2, a 3/3, a 4/2 or even a 4/3-way valve, in particular a valve system as disclosed in DE-A-10 2012 020 999, the content of which hereby is incorporated herein by reference. So z. For example, a single switch may be provided which, depending on the position, ensures that the medium flows into or out of the respective support cylinders. In particular, the switch is able to achieve an intermediate position of the eccentrically adjustable compression piston by activating or deactivating a control line, which should open in this case laterally in one of the support cylinders.

It is preferably provided when the VCR piston engine is a control unit has provided, each coordinating an opening and closing of each first and at least second control line to set different compression ratios. DE-A-10 2012 014 918 as well as DE-A-10 2012 020 999 describe VCR systems or actuation units for VCE systems. These two applications will be referred to in terms of the connecting rod, its function with the adjustable compression piston, with respect to the adjustment system as well as the Aktuierungseinheit in the context of the disclosure of the present invention, whereby the contents of these documents are the subject of the present patent application.

According to a further aspect of the invention, which can be used with the proposed VCR piston engine as well as independently, a method for operating a VCR piston engine is proposed, wherein a stroke adjustment of the compression piston by means of an adjustment mechanism of the connecting rod, wherein the bearing pin of the Compression piston is adjusted eccentrically ^¬ and opens a support piston of the adjusting mechanism in a support cylinder in the process a laterally opening into the support cylinder control line or closes. In this regard, reference is made to Applicant's PCT application PCT / EP2015 / 057474 of April 7, 2015, which discloses preferred VCR reciprocating internal combustion engines, as well as other methods of operation, the contents of which are hereby incorporated herein by reference.

Furthermore, there is the possibility that the crankshaft is eccentrically mounted and above the compression ratio is changeable. Such is evident, for example, from DE-A-10 2009 043 505, the contents of which are hereby incorporated by reference into the subject matter of the present patent application and to which reference is made in the entirety of the disclosure in this respect. According to a further aspect of the invention, program code means are also proposed for implementation in a control unit, preferably in an engine control unit of a VCR reciprocating internal combustion engine as above and also as described below, wherein the program code means in use one or more methods as described above and as described below , implement.

In principle, the compression ratio of a reciprocating internal combustion engine can be set simultaneously for all cylinders or for all cylinders of a cylinder bank or can be adjusted for the individual cylinders of the reciprocating internal combustion engine, in all cases mentioned above either actively or passively. Here, preferably, the geometry of an engine component such as the connecting rod, the crank shaft ^¬ radius, seal piston changes the support of the crankshaft and / or the storage of the encryption on the connecting rod and thus the effective connecting rod length. Be ^¬ preferably this is done hydraulically, ie using a medium. Here, the motor oil is especially suitable as a medium. The active adjustment means that by the action of external adjusting forces on the adjustment mechanism, an adjustment of the engine component in question is achieved. The passive adjustment states that are exploited in the engine component during operation of the internal combustion engine forces acting as the gas pressure forces and the forces of gravity to effect an adjustment of the Triebwerkskompo ^¬ component. In the passive adjustment so it comes due to the use of these forces to an automatic adjustment of the engine component, while in the active adjustment from the outside, ie in addition to the aforementioned forces or independently of these even more adjustment forces are introduced.

Further advantageous embodiments and further developments are specified in the following figures. However, the resulting respective features are not limited to individual figures or embodiments. Rather, one or more features thereof may be different from other features the above description in addition to further developments. Show it:

Figure 1 shows a detail of an internal combustion engine in the form of a connecting rod shown schematically as a 3-point connecting rod, which allows three different densities.

Fig. 2 and Fig. 3

show a mechanical switching to the various switching states and thus compression states at the 3-point connecting rod of FIG.

1 to be able to adjust

4 shows a schematic view of a further embodiment of a 3-point connecting rod with outgoing control channels,

5 shows a first state as a final state "shigh",

6 shows an average compression position "smid", FIG. 7 shows a compression position "slow",

FIG. 8 shows an enlarged view of FIG. 6 with an intermediate compression "smid", FIGS. 9 to 11

in the illustrated embodiment with two control channels at the bottom and a single control line laterally merging on the Massekraftzylinder MK possible, realizable switching sequences, and

FIGS. 12 to 14

an example of a possible interconnection. In the following, the invention will be described with reference to a piston engine in the form of an internal combustion engine with variable effective length of the connecting rod ^¬ . However, the following individual features are thus not limited to an internal combustion engine with such a VCR system, but can also be used in another type of piston engine and in other operating VCR systems.

Fig. 1 shows a section of an internal combustion engine in the form of a connecting rod. An existing two-stage variant of a length-variable connecting rod is extended by at least one further stage. Fig. 1 shows an off ^¬ design, by means of a change in the Dilute ichtungsverhältnisses is ubkol benverbrennungskraftmaschine made ^¬ light in a piston engine 1 in the form of an H. In the following, the same reference numbers are used for the same components. The connecting rod 17 has a G roßes connecting rod bearing eye 3 and a small connecting rod bearing eye 2 on. In the small connecting rod bearing eye 2 is in turn an Ex ^¬ center 5 angeord net, which is stored d rehbar. The eccentric 5 has a bore 18 for receiving a Kol benbolzens. At its U mfangsfläche the eccentric 5 has a toothing 19. With this toothing 19, the eccentric 5 is mechanically connected by positive engagement with a lever system 20, which acts as a support mechanism and preferably also as a backstop. The lever system 20 has a formschlüssig connected to the eccentric 5 Verstel lelement 6 and a first lever 21 and a second lever 22. Via the adjusting element 6, the two levers 21, 22 are firmly coupled together. About the teeth 19 turn the levers 21, 22 thus also d rehfest connected to the eccentric 5. The Verstel lelement 6 is net angeord in a recess 23 in the connecting rod 17. From Fig. 1 it can also be seen that the Verstel lelement 6 is axially guided in the recess 23. Further, the lever system 20 has connecting joints 24 on the adjusting element 6. About the connection joints 24 piston rods 25 are hinged. In the connecting rod 17 turn Stützzyl are inderbohrungen 26 arranged. In d ies support piston 27 are guided, on which the piston rods 25 are articulated. By this arrangement, opposing strokes of the two support pistons are directly related to a rotation angle of the eccentric 5. The support cylinder bores 26 in the connecting rod 17 are closed by check valves 28 to the large connecting rod eye 3, so that in each case a working space 29 is formed. The working space can thus serve as a damping volume as well as a support in the event of a backstop. In the big connecting rod bearing eye 3 Pleuellagerschalen 30 are arranged. The Pleuellagerschalen 30 are provided with openings 30.1. Since the bearing shells 30 are provided with a circumferential groove which is in communication with an oil supply via the crankshaft, an oil pressure is applied in the groove at all times. This oil pressure is transferred at any time to the check valves 28. These open or are closed depending on the working pressure present in the working chamber 29. The exact sequence of movement with when changing the compression ratio from large to small and vice versa is otherwise apparent from the above cited documents, in particular z. B. from DE-A-10 2005 055 199. In addition, there is also the possibility that instead of a circuit on the working pressure and a total circuit of control lines and control channels by z. B. a switch is enabled. The operation of the connecting rod 17 for setting a different compression ratio ^¬ is exemplified in the following example of setting a low compression ratio. In at least one of the two support cylinders, the first support cylinder 31.1 and the second support cylinder 31.2, by at least one additional control line 32 z. B. in the form of a channel which is not attached to the bottom of the support cylinder, introduced a further locking stage and thus a further compression stage of the combus ^¬ tion motor. The arranged in the stroke range of the second support cylinder 31.2 control line 32 may, for. B. be controlled with a variable resistor. The control channels 33.1, 33.2 at the bottom of the two support cylinders are closed when the control line 32 is open in the stroke region of the one support cylinder. For this purpose, ver ^¬ referred to the content of DE-A-10 2011 108 790, whose content is hereby part of the disclosure of this patent application. The open control line 32 causes a flow of oil from the second support cylinder 31.2 until the control line 32 is closed by a control edge, which preferably corresponds to the lower edge of the support piston. By closing the control line 32 in the stroke region of the support cylinder both support cylinders 31.1, 31.2 are closed and locked. Additional compression stages can be achieved by further, analogously designed control lines in the stroke range of the support cylinder, preferably in the second support cylinder 31.2. The blocking of the respective control channels 33.1, 33.2 or the control line 32 or of a plurality of control lines is preferably realized by means of a switch 34.

An advantage of the proposed solution results from the possibility of being able to avoid complex control of the system by means of actuators. Rather, the proposed solution can be used to exploit acting forces and moments on the system can, as will become clear ^¬ ver. The pointing in the direction of eccentricity, based on the illustration in Fig. 1 left support cylinder takes over the support of the resulting from the gas forces moments, the other support cylinder equivalent to the support of the inertial forces. Hereinafter, the two sides of the connecting rod are called "GKS" (gas force side) and "MKS" (mass force side). Both support cylinders can be filled with oil from the lift bearing if necessary, a check valve associated with each support cylinder prevents the oil from flowing out. About z. B. a 3/2-way switching valve can be opened either the GKS or the MKS. This combination of check valves and switching valves forms a hydraulic freewheel whose direction of travel can be selected. In the case of the selected position of a high compression ratio "s_high", the mathematically positive moments acting on the eccentric are based on the GKS oil column. The mathematically negative moments resulting from the inertial forces are transmitted in this position via a direct, metallic contact of the MKS support piston on the connecting rod. In the position of a low compression ratio "sjow" the conditions are reversed. A positive side effect for the position "ε_Ιονν" is that the gas forces usually higher in this position are no longer supported on the oil column and so the oil pressure in the support cylinder remains at a lower level. With this construction, a connecting rod can be realized that can take two stable effective length settings (2-point connecting rod).

For a 3-point connecting rod or multi-point connecting rod additional intermediate positions are necessary in accordance with the additionally adjustable compression ratios. The sum of intermediate positions and end positions must correspond to the number of compression stages or ratios and thus the number of control lines 32 and control channels 33.1, 33.2, wherein the switch 34, preferably a mechanical switch, in each of the positions exactly one control channel 33.1, 33.2 and Control line 32 either release itself or must open via a valve and the other control channels 33.1, 33.2 or control lines 32 to close.

In Fig. 1 is also schematically illustrated an engine control ECU, which is in connection with various sensors such as air mass sensors, lambda probe or temperature sensor, for. B. in an exhaust gas purification device such as a NOx storage catalyst. In the ECU, the information converges so that either by means of stored maps and / or by one or more models the particular method described above can be implemented and the corresponding compression ratio can be adjusted, the respective other components in particular of the engine and the exhaust line are taken into account

The blocking of the respective control channels or control lines can be effected, for example, by a mechanical switch 34 arranged in or on the connecting rod, as can be seen by way of example from FIG. 2, wherein in FIG. 3, the mechanical switch is shown enlarged by way of example. The mechanical switch 34 can correspond as far as possible to the modes of operation shown in DE-A-10 2005 055 199 and described in DE-A-10 2012 014 918. right. With each revolution of the crank, the switch 34 moves in the direction of the arrow 33 between two ramps 36 of a U-shaped cam member 35. By lateral displacement of the cam member 35 in one of the two directions of the double arrow 37, the switch 34 comes into contact with one of the ramps 36 and is displaced in one of the two directions according to double arrow 38 to realize an intermediate position, the "inner" width of the cam member 35, d. H . the distance between the two ramps 36 are only slightly larger than the length of the mechanical switch 34 can be selected. The inner width of the cam member 35 must be at least so large that a jamming or jamming of the mechanical switch 34 is prevented in the cam member 35, but may be selected so wide that the mechanical switch 34 in the desired intermediate position and not in the next Between or end position engages. In principle, the catch in the intermediate position of the mechanical switch 34 can also be achieved via other mechanisms. For example, a blocking of the adjustment in an intermediate position is conceivable, which automatically unlocks after completion of the adjustment and releases a further adjustment. This blockage can be triggered, for example, by centrifugal or acceleration forces. At standstill of the mechanical switch 34 in the intermediate position, the blocking is then released again due to the lack of driving centrifugal or acceleration force.

As an alternative to the mechanical actuation of the mechanical switch 34 with a cam member 35 and hydraulic switches that are controlled for example via pressure pulses, as well as any other type of switch are conceivable, as long as they can provide the necessary number of switching positions described above. Fig. 4 shows, by way of example, a simplified, schematic representation of a further possible embodiment of a connecting rod with an adjustable compression ratio. As shown, in this case the control line 32 are again laterally and the control channels 33.1, 33.2 of the respective support cylinder arranged downwardly away from the bottom of the support cylinder. The remaining reference numerals designate in principle the same or similar structural components, as they emerge from Fig. 1.

In the following, a sequence of the displacement of the respective support cylinders will be explained in a schematic representation.

FIG. 5 shows a first state as end state "shigh" due to a stop situation in one of the two support cylinders, wherein a high compression ratio is set. The schematic diagram shows a completely hydraulically locked gas-fired power cylinder GK, wherein a control channel not shown in detail is locked at the bottom of the gas-power cylinder GK as well as at the bottom of the mass cylinder MK. The filling with oil of the gas power cylinder GK is indicated by hatching. Furthermore, a laterally outgoing control line of the mass cylinder MK is locked by the associated piston.

Fig. 6 shows an average compression position "smid" on. This is achieved by the two cylinders are locked at the bottom of the mass and gas power cylinder in the mass force cylinder and gas power cylinder, however, the side-opening control line is just completely closed. As a result, the hatched oil flow up to the height of the junction of the control line and form an oil cushion.

Fig. 7 shows a further end position, namely a compression position "slow". Here is a completely hydraulically locked mass force cylinder MK, in which the control line as well as the opening into the ground control channel of the mass cylinder are locked. Thus, FIGS. 5 to 7 illustrate the sequence which is possible when adjusting from one end position to the other end position, taking into account at least one intermediate position, for example centrally as well as eccentrically to the respective end positions can be arranged.

Fig. 8 shows again in an enlarged view, Fig. 6 with an intermediate compression "smid" to show a peculiarity that may occur depending on the configuration. While the two in the bottom of the respective control cylinder opening control channels are locked, the laterally opening control line of the mass cylinder MK is open. A blocking of the control line of the mass cylinder MK is effected by closing the control channel by means of the illustrated piston edge. However, above the confluence of the control line, the piston edge in the mass-force cylinder MK, however, can not shut off the control line. Although this avoids a "pumping up" of the oil cushion, which is indicated by hatching, in the mass force cylinder MK, there is a "sagging" due to a small leakage due to the acting load of the gas force in the gas power cylinder GK. As a result, the control line is again released partially, since the piston edge in the mass force cylinder MK rises in this sagging according to the kinematic conditions. By lifting the piston in the mass cylinder MK oil flows after, for. B. through the control channel in the ground. In the mass combustion cylinder MK aspirated oil is then during the gas impact force discharged again through the opened by the angehobe ^¬ NEN piston control line due to the inertial force, and the control line is blocked again by the lowering of the piston. In this way, the oil which has flowed into the mass-flow cylinder is discharged again. Within a cycle thus oscillates the eccentric, via which the two pistons of mass and cylinder cylinders are connected to one another by a position such. B. a middle position.

FIGS. 9, 10 and 11 show the realizable switching sequences which are possible laterally on the grounding force cylinder MK in the illustrated embodiment with two control channels at the bottom and a single control line. In this embodiment, in which there is no laterally opening control line on the gas-force cylinder GK, an adjustment is possible as follows: a) Adjustment of "slow" to "smid" and from "smid" to "shigh" b) Adjustment of "slow" to "shigh" without "smid" c) Adjustment of "shigh" to "slow"

An adjustment of "shigh" to "smid" is in the presented embodiment so readily not possible, however. This is due to the aforementioned switching states that are provided, namely

"Slow":

completely hydraulically locked mass force cylinder, both lines, namely control line and control channel of the mass cylinder are locked

"Smid":

partially hydraulically locked mass force cylinder, both in the ground opening channels of inertial and gas power cylinder locked "shigh":

completely hydraulically locked gas power cylinder, control line of the mass cylinder and control channel of the gas power cylinder locked; The Steuerlei ^¬ tion of the mass-flow cylinder should possibly be closed by the piston, but must be completely disabled at the latest when switching to avoid the intake of air.

The respective switching positions for the respective compression settings from FIGS. 9 to 11 are shown by way of example in FIGS. 12 to 14 according to a possible interconnection. In this case, the respective control channels, which open into the bottom of the mass force cylinder and the gas force cylinder, are indicated as channel MK or channel GK with location "down." The control line, in turn, is referred to as channel MK intermediate position. The symbol "T" indicates a blocking position, where the T stands for separation, while an arrow indicates the possibility of flow. The advantage of this type of interconnection is that a very simple circuit can be used. Thus, such a circuit diagram can be implemented by means of a mechanical switch. The switch is z. B. only moved longitudinally. Also by means of a rotary switch moving such an interconnection can be implemented. Further exemplary embodiments may also provide the following possibilities:

An actuation for a third switching position provides, for example, to move a stop of the switch. The move can z. B. caused by the switching process previously or by an actuation unit. It is possible to design two switch positions so that only two positions remain, instead of three switch positions, which, depending on the switching direction, enable three switching states.

A sequential switching of the switch allows z. B. the use of a rotary switch. Also allows a sequential switching of the switch to represent a middle position on a mechanical latch, which z. B. prevents further flow of oil through a control channel.

Furthermore, it is possible to preferentially prevent suction of air by circuitry. Maybe z. B. an air supply via a control line, namely, if it inadvertently absorbs air. Such uncontrolled penetrating air can cause a malfunction in the system. To counteract this, on the one hand, an air outlet can be provided. Preferably, for this purpose, a collection point is structurally provided in the system, at which air, in particular also entrained air bubbles accumulate. About the collection point can then z. B. a valve circuit, the collected air to be drained. Also can be provided that there is another vent through which air can escape from the system. Alternatively but also in addition it can be provided to prevent the ingress of air into the system, preferably to prevent constructive, for example, to prevent it by a valve. For example, this may be provided in the control line, a check valve. Preferably, the check valve is integrated in an above circuit. Then there is the possibility with such a switch, both to effect the interconnection of the control line and to avoid the suction of air. The embodiments shown show only by way of example various possibilities, but without excluding other embodiments.

The invention can be further alternatively rewrite by one of said following feature groups, in which the characteristic groups with- any are combined with each other and individual features of one Merkmalsgrup ^¬ pe with one or more features of one or more other groups of features and / or described one or more of the above- Embodiments can be combined. 1. A method for operating a Hubkolbenverbrennungskraftmaschine ins ^¬ particular with an adjustment of an effective length of a connecting rod of a cylinder, wherein the over adjustable compression ratio ^¬ at least during operation of Hubkolbenverbrennungskraftmaschine ge ^¬ changes and this is matched with at least the current operating state of another engine component.

2. The method according to item 1, wherein the compression ratio is changed depending on the activation of an EGR map-based or model-based.

3. The method according to item 1 or 2, wherein an external exhaust gas recirculation is carried out, wherein a parameter characterizing this exhaust gas feedback is determined and evaluated by a control unit, wherein a cooling of the external exhaust gas recirculation takes place, which is accompanied by an increase in compression as well as a shift of a switching point to a lower compression in a map towards a higher load. Method according to one of the numbers 1 to 3, wherein for generating a faster heating of a catalyst Hubkolbenverbrennungs- the engine, a lower compression is set, wherein from reaching a minimum temperature of the catalyst, the compression is higher if necessary adjusted. Method according to one of the preceding figures, wherein in a changeover between different maps associated with different densities, the target torque is kept the same, preferably such that in a spark-ignition internal combustion engine an adjustment of a higher compression is associated with the shift The injection for the at least one cylinder in the direction of late or, in the case of a self-igniting reciprocating internal combustion engine, an adjustment of a lower compression is accompanied by the shifting of the injection for at least one cylinder in the direction of the characteristic map to which the changeover is made. A method according to item 5, wherein a desired value of a boost pressure, a target value of an injection pressure and a target value of an exhaust gas recirculation are also subject to an adaptation when switching from a first to a second map. Method according to one of the preceding figures, wherein one or more switching thresholds for switching over from a characteristic field of an engine Control are changed to another map of the engine control at a change in the compression ratio. The method of item 7, wherein a cylinder deactivation is provided with a change in the compression ratio of a fired cylinder, wherein a switching threshold is changed from one map to another map in the fired cylinder to accommodate a changed optimum of action. Method according to item 7 or 8, wherein a compression ratio of a non-fired cylinder is reduced with the cylinder deactivation. Method according to item 7 or 8, wherein a compression ratio of a non-fired cylinder is increased with the cylinder deactivation. Method according to one of the preceding figures, wherein a change in the compression ratio is used for peak pressure control. Method according to one of the preceding figures, wherein a change in the compression ratio is used for knock control. Method according to one of the preceding figures, wherein a fuel quality is determined, wherein an adaptation of a map in dependence on the determined fuel quality, wherein a switching threshold for a changeover from one compression ratio to another compression ratio is changed. Method according to one of the preceding figures, wherein an ignition timing change is made via a change of the compression ratio, the ignition timing change being effective at least in the next cycle after the compression ratio has changed. 15. Method preferably according to one of the preceding figures, wherein, in the case of water injection, the changeover thresholds for changes in the compression ratio from one characteristic field to the other are different.

Method according to item 15, wherein a condensate is used by a heat exchanger and / or an air conditioning system for water injection.

Method according to one of the preceding figures, wherein the operating state of an exhaust gas recirculation system and / or a Abgasnachbe ^¬ treatment system is taken into account for adjusting and / or changing the compression ratio.

18. The method according to item 17, wherein if the exhaust gas recirculation system and / or the exhaust aftertreatment system is still not operable due to low temperatures, the compression ratio is set so that the lowest raw emissions are formed, whereas to achieve a lower one Kraftstoffverbauch the Verd ichtungs ^¬ ratio is preferably adjusted at sufficient temperature and / or upon reaching each of the aktuel len operating state of Hubkolbenver- brennu ngskraftmaschine nominal operating conditions of Abgasnachbehandl system.

19. The method according to item 17 or 18, wherein for a first period in which an external exhaust gas recirculation is not yet carried out, in particular during a period of too low tempera ture a

Exhaust gas purification plant, the compaction is high, h in contrast with reaching a sufficient temperature r the exhaust gas purification plant the compaction is lowered. 20. Method according to one of the preceding figures, wherein a plurality of cylinders of the Hubkol benverbren combustion engine unterschiedl I are switched to each other with respect to their respective Verd ichtung, preferred wise to use one of the cylinders as a compressor or expander in an exhaust heat recovery system.

Method according to one of the preceding figures, wherein a mode changeover, preferably from an HCCI mode to an SI mode or vice versa, is accompanied by a change of the adjustable compression ratio, wherein before the mode changeover the compression ratio is lowered and after the mode changeover the compression ratio increases again becomes .

VCR reciprocating internal combustion engine with an adjustable compression ratio, wherein one or more methods are implemented according to one of the preceding paragraphs.

Program code means for implementation in a control device, preferably an engine control unit of a VCR reciprocating internal combustion engine according to claim 22, wherein the program code means in use implement one or more methods according to any of the numbers 1 to 21.

B EZUGSZE IC H E N LIST

1 piston engine

2 small connecting rod eye

3 large connecting rod eye

5 eccentrics

6 adjustment

17 connecting rods

18 hole

19 toothing

20 lever system

21 lever

22 levers

23 recess

24 connecting joints

25 piston rods

26 support cylinder bores

27 support pistons

28 check valve

29 workspace

30 connecting rod bearing shell

30.1 Breakthrough

31.1 first support cylinder

31.2 second support cylinder

32 control line

33.1 control channel

33.2 control channel

34 switches

35 cam member

36 ramps

37 double arrow

38 double-headed arrow

Claims

claims

1. A method for operating a reciprocating internal combustion engine with adjustable compression ratio, in which at least one cylinder of the reciprocating internal combustion engine is to be operated in dependence on at least one first desired operating parameter, wherein

the compression ratio during operation of the reciprocating internal combustion engine is changed if necessary, in dependence on at least the first desired operating parameter, and the current operating state of at least one engine component of the reciprocating internal combustion engine is determined, wherein the current operating state of said at least one engine component describes whether a change of Compression ratio is currently allowed, and

an adjustment of the compression ratio is performed independently of the first desired operating parameter only if the current operating state of the at least one engine component permits.

2. The method of claim 1, wherein the at least one engine component is an EGR system, and when the at least one desired compression ratio operating parameter changes with the EGR system activated and the compression ratio adjustment signal is signaled Compression ratio initially remains unchanged until the desired operating parameter changes further in the direction of the requirement of the change in the compression ratio.

3. The method according to claim 1, characterized in that the at least one engine component is an exhaust gas recirculation system and / or an exhaust aftertreatment system, that if the exhaust gas recirculation system and / or the exhaust aftertreatment system is not yet operational due to low temperature, the compression ratio is set so that the lowest raw emissions are formed, whereas at sufficient temperature and / or upon reaching each dependent on the current operating state of the reciprocating internal combustion engine nominal operating conditions of the exhaust gas recirculation system and / or the exhaust aftertreatment system, the compression ratio to achieve a lower fuel consumption is adjusted.

A method according to claim 3, characterized in that for a first period in which an external exhaust gas recirculation is not yet performed and / or during a period of too low operating temperature of the exhaust gas recirculation system and / or the exhaust aftertreatment system, the compression is set high, whereas upon reaching the Operating temperature, the compression is reduced.

A method according to claim 1, characterized in that the at least one engine component is a catalyst and the current operating state of the catalyst represents its temperature and that a change in the compression ratio towards a larger value during a heating phase of the catalyst is omitted until the catalyst is at its operating temperature has reached.

Method according to one of claims 1 to 5, characterized in that the reciprocating internal combustion engine is operated on the basis of different engine control maps and that are stored in the maps switching thresholds for varying the compression ratio from low to high and from high to low, which varies from one characteristic map to another and / or the same.

A method according to claim 6, characterized in that the reciprocating internal combustion engine is operated in dependence on a desired torque, that different engine control maps are assigned to different compression ratios and that in a Um- Shift from one engine control map to another engine control map the target torque is kept substantially equal.

8. The method according to claim 7, characterized in that in a spark-ignition internal combustion engine an adjustment to a higher compression ratio is accompanied by the displacement of the injection for the at least one cylinder in the late direction or in a self-igniting reciprocating internal combustion engine, the adjustment to a low compression ratio goes along with the shift of the injection for the at least one cylinder in the direction of early, based on the characteristic map, is switched to the.

9. The method according to claim 6, characterized in that a desired value of a boost pressure, a target value of an injection pressure and / or a desired value of an exhaust gas recirculation is also subject to an adaptation when switching from one map to another map.

10. The method according to claim 6, characterized in that a cylinder deactivation is provided with a change in the compression ratio of a firing cylinder, wherein when switching from one engine control map to another engine control map, a switching threshold in which the compression ratio for the firing cylinder is changed, according to a changed optimum effect is changed.

11. The method according to claim 10, characterized in that the compression ratio of a non-firing cylinder at cylinder deactivation is reduced and / or that the compression ratio of a non-firing cylinder is increased in cylinder deactivation.

12. The method according to claim 1, characterized in that the current operating state of the at least one engine component describes the desired value of a cylinder peak pressure regulator and that by means of a change in the compression ratio, a peak cylinder pressure control takes place.

13. The method according to claim 1, characterized in that the current operating state of the at least one engine component of the setpoint describes a knock control and that by means of changing the compression ratio a knock control takes place.

14. The method according to any one of the preceding claims, characterized in that in a water injection, the switching thresholds for the changes of the compression ratio of a engine control map to another engine control map is different.

15. The method according to any one of the preceding claims, characterized in that a mode change from a HCCI operation to a SI operation or vice versa is accompanied by a change in the compression ratio, wherein before the mode changeover, the compression ratio lowered and after the mode changeover the compression ratio again is increased.

16. A method for operating a reciprocating internal combustion engine with adjustable compression ratio, in which at least one cylinder of the reciprocating internal combustion engine is to be operated in dependence on at least a first desired operating parameter, wherein

the compression ratio is changed during operation of the reciprocating internal combustion engine, in dependence on at least the first desired operating parameter, the current operating state of at least one engine component is determined,

is checked before an adjustment of the compression ratio, whether the at least one engine component is still operable in the current operating state when the compression ratio is adjusted, and

if this is not the case, the engine component is operated in an operating state associated with the compression ratio to be adjusted and the compression ratio is changed.

17. The method according to claim 16, wherein the current operating state of the at least one engine component describes the ignitability of the fuel of the reciprocating internal combustion engine and the more ignitable the fuel, the earlier from a higher compression ratio to a lower compression ratio or later of a lower one Compression ratio is switched to a higher compression ratio when the at least one desired operating parameters of the reciprocating internal combustion engine signals a change in the compression ratio.

18. The method according to claim 16, wherein the current operating state of the at least one engine component describes the injection of fuel into the at least one cylinder and the beginning and / or end of an injection interval is changed depending on the compression ratio to be set such that the fuel injection jet substantially does not impinge on the compression piston of the at least one cylinder having different relative positions to the injection jet during the same times of a working cycle of the reciprocating internal combustion engine as a function of the compression ratio.

19. VCR reciprocating internal combustion engine with an adjustable compression ratio, wherein one or more methods are implemented according to one of claims 1 to 18.

20. Program code means for implementation in a control unit, preferably an engine control unit of a VCR reciprocating internal combustion engine according to claim 19, wherein the program code means in use implement one or more methods according to one of claims 1 to 18.