WO2006017870A2

WO2006017870A2 - Method for the operation of an internal combustion engine

Info

Publication number: WO2006017870A2
Application number: PCT/AT2005/000288
Authority: WO
Inventors: Dirk Denger; Alexander Pinter
Original assignee: Avl List Gmbh
Priority date: 2004-08-19
Filing date: 2005-07-21
Publication date: 2006-02-23
Also published as: DE112005001975A5; WO2006017870A3

Abstract

The invention relates to a method for operating an internal combustion engine comprising at least four cylinders with a fully variable valve drive for at least one intake valve and one discharge valve per cylinder (CYL), the internal combustion engine being operated with partly shut-off cylinders (CYL) in at least one partial load range (TL1, TL2). In order to increase the thermodynamic efficiency during partial load operation while maintaining the greatest possible smoothness of operation, the cylinders (CYL) are alternately shut off and reactivated in at least one partial load range (TL1, TL2). Preferably, the shut-off phase (RI, ZAS, RO) of a deactivated cylinder (CYL) extends across a minimum of two and a maximum of three operating cycles (A, B, C, D).

Description

Method for operating an internal combustion engine

The invention relates to a method for operating an internal combustion engine having at least four cylinders with fully variable valve train for at least one input and one exhaust valve per cylinder, wherein the internal combustion engine is operated in at least one partial load range with partially disabled cylinders. Furthermore, the invention relates to a method for operating an internal combustion engine, in which intake and exhaust valves are actuated fully variable, wherein the Öffnungszeit¬ point of the intake valve and the closing time of the exhaust valve is changed depending on the engine load.

WO 00/47882 Al describes various methods for operating an internal combustion engine with variable gas exchange control times, wherein, inter alia, every six cycles or eight cycles a working cycle is provided. This should reduce consumption and emissions. However, in 4-cylinder internal combustion engines in particular, 6- or 8-stroke operation has disadvantageous effects on smoothness.

DE 101 54 947 A1 describes an internal combustion engine with a variable displacement, wherein predetermined or selected cylinders can be operated in a non-ignited mode. The inlet valves are controlled by electromagnetic actuators. The predetermined or selected cylinders may be operated in a compressor mode, wherein the intake air valves of cylinders operating in the compressor mode are controlled to selectively supply compressed air in the charge manifold when additional torque is desired.

It is known to control the combustion of an internal combustion engine mixture formation and ignition by the use of electronic systems both cylinder and cyclic selectively completely flexible or regulate. Electrohydraulic valve control device for realizing such a fully variable valve actuation are known from DE 101 27 205 A1 and DE 101 34 644 A1.

It is known, in order to improve combustion in an internal combustion engine, to control or regulate mixture formation and ignition completely flexibly by use of electronic systems, both cylinder-wise and cyclically-selectively. However, in conventional systems, the charge change is still mostly mechanically coupled with the crankshaft. The control of the gas exchange valves by camshafts allows only to a limited extent to adjust the timing and / or stroke of the gas exchange valves according to the operating conditions of the internal combustion engine. In the case of variable-length variable valve control devices, both the stroke of the gas exchange valve and its control time can in principle be set freely. As a result, the operating behavior of the internal combustion engine, their specific fuel consumption and their emissions can be improved. Electrohydraulic valve control devices for realizing a fully variable valve actuation are known from DE 101 27 205 A1 and DE 101 34 644 A1. In comparison to variable mechanical or variable electromagnetic valve control, the variable electrohydraulic valve control offers advantages in terms of charge movements and pumping losses.

The object of the invention is to increase the thermodynamic efficiency while maintaining the greatest possible smoothness in a 4-stroke internal combustion engine in part-load operation. A further object of the invention is to increase the efficiency of an internal combustion engine, to lower emissions, to reduce fuel consumption and / or to increase the nominal power.

According to the invention, this is achieved in that the cylinders are alternately switched off and reactivated in at least one partial load range, wherein preferably the switch-off phase of a deactivated cylinder extends over at least two and a maximum of three operating cycles. The switch-off phase of each deactivated cylinder extends over a crank angle range of at least 1080 ° and at most 2160 °.

Preferably, at most three quarters of all available cylinders are turned off simultaneously.

During the shutdown phase, ignition is suspended and / or fuel injection is deactivated. During the shutdown phase of a cylinder whose intake and exhaust valves are at least largely kept closed. The shutdown phase of a cylinder is thereby initiated by a Rücksaugvorgang of residual gas through at least one open exhaust valve of the respective deactivated cylinder and concluded with a Ausschiebevorgang the residual gas through at least one open exhaust valve.

In the first or second partial load range, each cylinder is switched off and activated at least once within a certain crank angle range, preferably at a maximum of 3600 °, particularly preferably 2880 °.

The deactivation and activation of each cylinder takes place cyclically, whereby the start of the deactivation and the activation of the cylinders take place staggered over time, wherein preferably only one cylinder simultaneously starts or ends the shutdown. This allows a maximum of smoothness can be achieved.

A particularly advantageous embodiment variant of the invention provides that the internal combustion engine is operated in a first partial load range in a first cylinder deactivation mode, which substantially corresponds to a regular 12-stroke operation, wherein in each cylinder a power stroke is performed only every 2160 ° crank angle , wherein it is preferably provided that in the first part-load range only about every 540 ° crank angle a power stroke is performed in at least one of the cylinder. The 12-stroke operation is characterized by particularly high smoothness. The shutdown phase of each deactivated Zy¬ Linders extends over a crank angle range of about 1440 °. Every 540 ° crank angle begins a shutdown phase in any of the cylinders, whereby the cylinders are switched off and activated with a time offset according to the firing sequence. At the same time, half or three quarters of the cylinders are deactivated at the same time. In a 4-cylinder engine, therefore, two or three cylinders are always deactivated simultaneously.

The 12-stroke operation is in the lowest part-load range, preferably driven up to ei¬ nem effective mean pressure of about 2 bar. In comparison to a conventional 4-stroke operation, an indexed average pressure increased by a factor of 3 can be achieved by the 12-stroke operation per cylinder. The load increase of each activated cylinder causes a significant increase in the thermodynamic efficiency and has an extremely beneficial effect on fuel consumption. Since only every 540 ° takes place an ignition, the ab¬ given power is reduced in comparison to the 4-stroke operation to one-third.

In a further embodiment of the invention, it is provided that the internal combustion engine is operated in a second partial load range in a second or third cylinder deactivation mode, with two or three complete combustion cycles per cylinder between two successive shutdown phases with a total of two or three power strokes become.

In the second cylinder deactivation mode, the deactivation phase of each deactivated cylinder extends over a crank angle range of approximately 1440 °. Successive cylinder deactivations for two cylinders with non-overlapping shut-off phases begin in the second cylinder deactivation mode offset by 360 °, 900 ° or 1260 °.

In the third cylinder deactivation mode, the deactivation phase of each deactivated cylinder extends over a crank angle range of approximately 2160 °. The The following cylinder shut-offs in two cylinders with overlapping shut-off phases start offset by 360 °, 1620 ° or 1980 ° crank angle.

In the second or third cylinder deactivation mode, three cylinders are deactivated in at least one crank angle range in the case of a 4-cylinder engine. In another crank angle range, two cylinders are deactivated and in another crank angle range only one cylinder is deactivated.

It is preferably provided that the second partial load range then extends to the first part-load range up to an effective mean pressure of up to about 3.5 bar to 5.5 bar, preferably to about 4 bar.

In a further embodiment of the invention, it is provided that the internal combustion engine is operated in normal four-stroke operation in a third partial load range adjoining the first and / or second partial load range, wherein preferably the effective mean pressure in the third partial load range is greater than in second and / or first part load range.

Characterized in that during the deactivation of the cylinder, the inlet and Aus¬ laßventile are kept mostly closed, the remaining residual gas acts as a gas spring accumulator, whereby the losses can be kept as small as possible.

An increase in the efficiency and a reduction in emissions and fuel consumption can be achieved by the internal combustion engine in idle and low load range with little overlap or Unterschneidung the inlet and outlet valves and in the middle and upper part load range with greater overlap the intake and exhaust valves is operated as in Leerlauf¬ and low load range, wherein the idle and low load range opens the intake valves after the top dead center of the charge cycle and the exhaust valves in a range between about 300 ° to about 390 ° after the top dead center of the ignition and, wherein in the middle and upper part load range, the intake valves in a range between about 270 °, open to about 370 ° after top dead center of the ignition and the Auslaßven¬ tile after the top dead center of the charge cycle, preferably in a range between about 400 ° until about 540 ° after the top dead center of La¬ exchange change are closed.

It is particularly advantageous if the internal combustion engine is operated with overlap of the inlet and outlet valves in the full load range, wherein the overlap is preferably smaller than in the middle and upper part load range and greater than in the idle and low load range, and wherein the inlet valves are preferably between approximately 300 ° and about 440 ° after top dead center of Ignition open and the exhaust valves are closed in a range of about 330 ° to about 440 ° after the top dead center of the ignition.

Due to the flexible control of the charge exchange as a function of Lastzu¬ state more accurate control of the combustion is possible.

A significant improvement in the thermodynamic efficiency, the fuel consumption and the emissions, as well as the rated power can be achieved if the start of the opening (t _E o) and opening duration (Δt _E ) of the exhaust valves are selected such that the following applies:

t _{£ 0} = 320 * e- '' ⁰⁰²⁶⁵ ^ ± 45.

It is particularly advantageous if, in the idle and low load range, the exhaust valves between 230 ° to about 310 ° crank angle after the top dead center of the ignition are opened, the opening duration of the exhaust valves is about 50 ° to about 130 ° crank angle, and if the exhaust valves are opened in the middle and upper part-load ranges in a range between about 130 ° to 270 ° crank angle after the top dead center of the ignition, wherein the opening duration of the exhaust valves is between about 100 ° to about 280 ° crank angle. Furthermore, it can also be provided that in the full-load range, the exhaust valves are opened in a range between about 70 ° to about 190 ° crank angle after the top dead center of the ignition, wherein the opening duration is between about 260 ° to 430 ° crank angle. In at least one engine operating point in the idling, low-load and part-load range, at least one intake valve is opened at the earliest at 180 ° crank angle after the top dead center of the ignition for a maximum of 240 ° crank angle. It can further be provided that the exhaust valves are opened in at least one engine operating point of the full load range for a period of at least 340 °.

Tests have shown that indicated consumption and emissions can be significantly improved if the inlet valves are operated such that the following relationship between the valve lift and the opening duration of the inlet valve applies over the entire engine operating range:

(0.753 - 0.15) * _e ⁰ - ⁰⁰⁷⁸⁷ ^ '- 0.75 ≤ h, ≤ (0.753 + 0.2) * e ⁰ - ^{00787 *} ^ + 1.

The invention will be explained in more detail below with reference to FIGS. They show schematically:

1 shows the timing of a 4-cylinder internal combustion engine in 4-stroke operation. FIG. 2 shows the clock sequence of a 4-cylinder internal combustion engine in the second cylinder deactivation mode; FIG.

3 shows the timing sequence of a 4-cylinder internal combustion engine in the third cylinder deactivation mode;

4 shows the clock sequence of a 4-cylinder internal combustion engine in the first cylinder deactivation mode;

5 shows the timing sequence of a 4-cylinder internal combustion engine during a switching process from 4-stroke operation into the first cylinder deactivation mode;

6 shows the timing sequence of a 4-cylinder internal combustion engine during a switching process from 4-stroke operation into the second cylinder deactivation mode;

7 shows the timing sequence of a 4-cylinder internal combustion engine during a switching process from 4-stroke operation into the third cylinder deactivation mode;

8 shows the timing of a 4-cylinder internal combustion engine during a switching from the second Zylinderabschaltmodus in the first Zylinderabschaltmodus.

9 shows the timing of a 4-cylinder internal combustion engine during a switching from the third Zylinderabschaltmodus in the first Zylinderabschaltmodus.

10 shows an engine map for the operating method according to the invention;

Fig. 11 is a consumption load diagram;

Fig. 12 is a valve timing diagram in which the exhaust port is plotted above the inlet start;

Fig. 13 is a valve timing diagram in which the exhaustion start is plotted over the exhaust duration;

Fig. 13a is a valve timing diagram in which the outlet end is plotted above the outlet beginning;

14 shows a valve operating diagram in which the valve lift of the inlet valve is plotted over the inlet duration; FIG. 15 schematically shows an electrohydraulic valve actuating device for carrying out the method; FIG.

Fig. 16 is a lift curve of a gas exchange valve;

FIG. 17 activation status diagrams for solenoid valves of the valve control device; FIG.

18 shows activation status diagrams for solenoid valves of the valve control device;

Fig. 19 is a valve lift diagram for full load;

Fig. 20 is a valve lift diagram for partial load; and

Fig. 21 is a valve lift diagram for idling.

In FIGS. 1 to 7, the clocks T 1 to T 49 are respectively indicated in the uppermost row, with clock T 49 corresponding to the clock 1. With OT 2/3 or OT 1/4 is indicated in the second line of the tables, which is the cylinder CYL 1, 2, 3, 4 is currently in top dead center TDC.

In conventional 4-stroke internal combustion engine, every 720 ° crank angle in each cylinder is a power stroke, as shown in Fig. 1. In a Brennkraft¬ machine with 4 cylinders CYL 1, 2, 3.4, the firing order is chosen so that every 180 ° takes place in any of the cylinders a power stroke. This ensures the greatest possible smoothness. A duty cycle consists of the cycles Ansau¬ gen A, compressing B, power stroke C and pushing out D. The firing order of the internal combustion engine shown in Fig. 1 is thus 1-3-4-2. Since a working cycle C takes place every 180 ° crank angle, the indicated mean pressure per cylinder, in particular in the partial load range, is relatively low, which adversely affects the thermodynamic efficiency.

In order to increase the indicated mean pressure and thus the thermodynamic efficiency, according to the described method, the engine at low load and / or speed in a first part load range TLL in a first Zylinderabschaltmodus 12T, in the second part load range TL2 in a second Zylinderabschaltmodus ZAS2 or a third Zylinderabschaltmodus ZAS3 and in a third partial load range TL3, and operated at full load VL in 4-stroke mode 4T, as can be seen from the mean pressure p _me - speed n - diagram of FIG.

In order to increase the efficiency, in particular in the lower part-load range, the cylinders CYL changeable in the first and in the second partial load range TL1, TL2 switched off and reactivated, with the shutdown of a deactivi¬ fourth cylinder extends over at least two and at most three working cycles. The shutdown phase RI, ZAS, RO of a deactivated cylinder CYL thus extends over a crank angle range CA of at least 1080 ° and at most 2160 °, wherein the shutdown phase of each cylinder 1, 2, 3, 4 with ei¬ ner Rücksaugphase RI by at least one open exhaust valve the respective deactivated cylinder is initiated and closed with a Ausschiebphase RO of the residual gas through at least one open outlet valve of the respective deacti¬ fourth cylinder. During the central switch-off phase ZAS of a cylinder 1, 2, 3, 4, its inlet and outlet valves are predominantly kept closed.

To achieve a high degree of uniformity, deactivation and activation of each cylinder CYL are performed cyclically. By staggering the beginning of the shutdown and the activation of the cylinder CYL a high degree of smoothness is achieved, it is advantageous if at the same time only with one cylinder, the shutdown begins or ends.

Both in the first and in the second partial load range TL1, TL2, each cylinder within a certain crank angle range CA, for example of at most 3600 °, is switched off and activated at least once. In the first Teil¬ load range TLL which up to an effective mean pressure p _me is from about 2 bar, the internal combustion engine is operated in a first Zylinderabschaltmodus 12T, which substantially corresponds to a 12-cycle operation. In this case, in each of the cylinders 1, 2, 3, 4, a power stroke C is performed only every 2160 ° CA crank angle. In the case of a 4-cylinder engine, only about every 540 ° crank angle is a work cycle C carried out in at least one of the cylinders 1, 2, 3, 4. The shut-off phase RI, ZAS, RO beginning with a return suction phase RI of the residual gas and ending with a discharge phase RO extends over a crank angle range of approximately 1260 °, as can be seen in FIG. The cylinders 1, 2, 3, 4 are switched off and activated offset in time in accordance with the firing order 1-2-4-3, wherein all 540 ° crank angles CA in any of the cylinders 1, 2, 3, 4 are a Shutdown phase RI, ZAS, RO begins. As a result, at least two cylinders CYL are always deactivated at the same time.

Since in the first part load range TLL only every 540 ° crank angle, a power stroke C takes place, a load increase of the respective activated cylinder takes place on the triple indicated mean pressure compared to the 4-stroke operation, while the total output power is reduced to one third. The increase in the indicated mean pressure directly causes an increase in the thermodynamic efficiency. In the second partial load range TL2, the internal combustion engine is operated in a second cylinder deactivation mode ZAS2 or a third cylinder deactivation mode ZAS3. The second partial load range TL2 adjoining the first part-load range TU extends up to about 4 bar effective mean pressure p _me . In the second or third cylinder deactivation mode ZAS2, ZAS3 there are crank angle ranges in which three cylinders 1, 2, 4 are deactivated, see clock 46 in FIG. 2 or FIG. 3. In a 4-cylinder engine, the engine is repeated Initial state of the clock Tl again at clock T49, ie after 8640 ° CA crank angle. In the first cylinder deactivation mode 12T, on the other hand, a repetition of the initial state already occurs at the cycle T13, as after 2160 ° CA of the crank angle.

In the second cylinder shut-off mode ZAS2, two consecutive complete combustion cycles A, B, C, D are performed per cylinder 1, 2, 3, 4 between two consecutive shutdown phases RI, ZAS, RO with a total of two power strokes C. The Abschalphase RI, ZAS, RO each deactivated cylinder 1, 2, 3, 4 starting with a Rücksaugphase RI of residual gas and ending with a Ausschiebephase RO of the residual gas extends over a Kurbelwinkel¬ area CA of about 1440 °. Cylinder deactivation begins with two cylinders with overlapping switch-off phases RI, ZAS, RO offset by 360 °, 900 ° or 1280 ° crank angle CA. Thus, the suck-back phase RI or the Ausschiebe¬ phase RO of the cylinder 4 begins 360 ° later than the Ausschiebephase RO of the cylinder 1 - compare clocks T7 and T9. The same applies to the cylinders 2, 3 in the clocks T14 and T16. The Rücksaugphase RI of the cylinder 2, however, begins only 900 ° after the Rücksaugphase RI of the cylinder 4 - compare T9 and T14 in Fig. 2. The Rücksaugphase RI of the cylinder 1 starts at all 1260 ° CA angle after the Rücksaugphase RI of the cylinder FIG. 3 shows identical clocks T16 and T23 in FIG. 2.

In the third cylinder deactivation mode ZAS3 illustrated in FIG. 3, three successive complete combustion cycles A, B, C, D are performed per cylinder with a total of three work cycles C between two successive shutdown phases RI, ZAS, RO. The shutdown phase RI, ZAS, RO of each deactivated cylinder extends over a crank angle range CA of approximately 2160 °. Auf¬ successive cylinder shutdowns in two cylinders with overlapping shutdown ZAS are started offset by 360 °, 1620 ° or by 1980 °. Thus, the difference of the cylinder deactivation start between the cylinder 1 and the cylinder 4 or the cylinder 2 and the cylinder 3 is 360 ° Kurbel¬ angle CA - compare clocks TIl and T13 or T22 and T24 in Fig. 3. Die Diffe¬ On the other hand, between the cylinder deactivation start of the cylinder 4 and the cylinder 2 is 1620 ° - compare clocks T13 and T22 in FIG. 3. The difference between the cylinder 3 and the cylinder 1 is even 1980 ° CA angle comparison clocks T24 and T35 in Fig. 3rd

In the third part-load range TL3, which adjoins the second part-load range TL2 an¬, and at full load VL, the internal combustion engine is operated in the conventional A-stroke mode Al.

FIG. 5 shows a switching operation from 4-stroke operation 4T to 12-stroke operation of cylinder deactivation mode 12T. The switching process begins in the Ta¬ belle in cycle T7 with a Rücksaugphase RI of residual gas of the first cylinder 1. Thereafter follow Rücksaugphasen RI in the cylinder 2 in the cycle TlO and in the cylinder 4 in the cycle T13, and in the cylinder 3 in the cycle T16. The switch back to the A-stroke mode 4T begins in the example shown with the cylinder 1 in the cycle T31 with an intake stroke A. From the cycle T36, the conventional 4-stroke operation is restored.

FIG. 6 shows a switching operation from the 4-cycle mode 4T to the second cylinder deactivation mode ZAS2. The switching process into the second cylinder deactivation mode ZAS2 begins with the cylinder 1 at the rate T7. Thereafter, the cylinder 4 in the cycle T9, the cylinder 2 in cycle T14 and the cylinder 3 in cycle T16 in the second Zylinderabschaltmodus ZAS2 is successively switched. The switching back from the second Zylinderabschaltmodus ZAS2 in the 4-stroke mode 4T begins in Aus¬ leadership example in clock T39 at cylinder 1, in which instead of a Rücksaugtak¬ tes RI a normal intake stroke A is performed. From the cycle T40, the internal combustion engine is again in the normal 4-stroke mode 4T.

FIG. 7 shows a switching process from the 4-cycle mode 4T to the third cycle shutdown mode ZAS3. The switching process into the third cylinder deactivation mode ZAS3 starts with the first cylinder 1 in cycle TI1. This is followed by cylinder 4 in cycle T13, cylinder 2 in cycle T22 and cylinder 3 in cycle T24. The switching back from the 4-stroke mode 4T to the third cylinder deactivation mode ZAS3 starts with the first cylinder in cycle T35, a normal intake stroke A being carried out instead of a recirculation phase RI of residual gas. From the cycle T36, the internal combustion engine operates again in 4-stroke mode 4T.

The advantages of the method described can be seen in the diagram shown in FIG. 11, where the specific fuel consumption BSFC is plotted in g / kWh above the mean effective pressure p _me . The curve MPFI shows the fuel consumption of a conventional internal combustion engine with multiple injection. The curve EHVS shows the specific fuel consumption of an internal combustion engine with electrohydraulic valve train, the curve DOD shows the fuel consumption in an internal combustion engine with electrohydraulic Valve gear when performing the second and third Zylinderabschaltmodus ZAS2, ZAS3 and the curve DOD12 shows the fuel consumption in a Brenn¬ engine with electrohydraulic valve train in carrying out the be¬ described method with switching to the first Zylinderabschaltmodus 12T in the first part load range TLl and switching to the second and third Zylinderabschaltmodus ZAS2, ZAS3 in the second partial load ranges TL2. It can clearly be seen that, in particular below an effective mean pressure of 2 bar, a significant reduction of the specific fuel consumption BSFC can be achieved.

All information regarding the opening and closing of the inlet or outlet valves is based on a 0.1 mm valve lift.

Fig. 12 shows a valve timing chart in which the closing timing t _{Ec of} the exhaust valves is plotted against the opening timing ti _{0 of} the intake valves. The axis values are related to the top dead center of the ignition. In the diagram, the idling and low-load range LL, the middle and upper partial load range TL and the full-load range VL are shown schematically.

In the idling and _low- load range LL, the opening time t _{ϊ0 of} the intake valves is after the top dead center OT _{LW of} the charge cycle, while the closing time t _Ec occurs before or after top dead center OT _{LW of} the charge cycle. There is thus an undercut or a slight overlap between intake and exhaust valves. In the case of valve undercutting occurs due to lack of rinsing to a retention of the residual gas and thus to a charge dilution for the next cycle, which in particular allows combustion control in the so-called HCCI operation (Homogeneous Charge Compression Ignition). By changing the control times and thus the undercutting or overlapping in the area HCCI delimited by the lines HCCI ₁ and HCCI ₂ , it is possible to control or regulate the combustion in HCCI mode by varying the amounts of residual gas in the cylinder.

In the middle and upper part load range TL, the intake valves are opened in a range between about 270 ° and about 370 ° crank angle after the upper dead center of the ignition OT _Z and the exhaust valves in a range of about 400 ° to 540 ° crank angle after top dead center the ignition OT _Z closed. By virtue of this more or less pronounced clear overlapping of the intake and exhaust valves, the cylinder can be optimized by adjusting the opening time ti _{0 of} the intake valves and the closing time t _{Ec of} the exhaust valves to optimize the temperature, residual gas content and mixture processing be, in particular in the partial load range TL by variable determination of the valve lift In _1, in particular the intake valves influencing the Ladungs¬ movement is possible. In the full-load range VL, the opening time ti _{0 of} the intake valves between 300 ° to 380 ° crank angle after the top dead center of the ignition and the closing time t _{EC of} the exhaust valves in the range between 330 ° to 440 ° crank angle after the top dead center of the ignition OT _Z einge¬ , which allows particularly good flushing and high full load efficiencies.

As can be seen in FIG. 13, the opening time t _{Eo of} the exhaust valves and the opening duration Δt _{E of} the exhaust valves are in a functional relationship, with the opening duration Δt _E becoming greater the sooner the exhaust valve is opened. Opening time t _Eo and opening duration .DELTA.t _{E of} the exhaust valves can both in the idle and low load range LL, in the partial load range TL, as well as in the full load VL be adapted to the respective requirements for achieving optimal combustion and optimized charge cycle losses. While in conventional internal combustion engines with cam-operated gas exchange valves, the opening timing of the exhaust valves between about 80 ° to 180 ° crank angle after the top dead center of the ignition and the Öff¬ opening duration .DELTA.t _{E of} the exhaust valves is independent of the load point between 240 ° to 340 ° crank angle, as shown in FIG 13 is indicated by dashed lines, can be varied with a fully variable valve train, in particular with an electro-hydraulic valve train opening time t _{Eo of} the exhaust valves and the opening duration .DELTA.t _{E of} the exhaust valves in a wide range and adapt to the requirements.

The opening duration .DELTA.t _{E of} the exhaust valves in the idle and low load range LL is between about 40 ° and 110 ° crank angle in the middle and upper Teil¬ lastbereich TL between about 100 ° to 280 ° crank angle and the full load range VL between about 260 ° to 430 ° crank angle , The most favorable opening time t _Eo idle and _low load range LL is about 220 ° to about 310 ° after the top dead center of the ignition OT _Z , in the middle and upper part load range TL between about 120 ° to about 270 ° after the top dead center of the ignition OT _Z and in the full load range VL between about 70 ° and about 190 ° after the top dead center of the ignition OT _2nd In this way, flushing, mixture preparation and residual gas content can be optimally adapted to the combustion requirements.

The opening time t _Eo can be represented as a function of the opening duration Δt _{E of} the outlet valves, as indicated by the line 1 in FIG. 13. All operating points lie within limits 2 and 3 over the entire engine operating range. Therefore, the following equation applies to the opening time t _{Eo of} the exhaust valves: 320 * _e - ⁰ ' ^{00265 Alε} - 45 <t _Eo ≤ 320 * e ^"0 ' ⁰⁰²⁶⁵ ^ + 45 (1)

The valve lift In ₁ and the opening duration Δti of the intake valves is of decisive importance for the height and quality of the charge movement in the cylinder. The range of the maximum charge movement should coincide with the range of the maximum residual gas requirement in the engine map. This condition is not always met in known variable valve actuation systems.

From the opening duration and the start of the opening of the exhaust valves from FIG. 13, the relationship between outlet end and outlet start shown in FIG. 13a can be directly derived.

Fig. 14 shows a valve timing chart in which the valve lift of the _r h Einlass¬ valves with symmetrical valve lifting function of both intake valves via the opening period At ₁ is applied, as indicated by the lines 4, 5 and 6. The following applies to curve 4:

h, = 0.753 V ' ^{00787 *} *' (2)

The lines 7 and 8 show Huberhebungen of known variable Ventilbetäti¬ supply systems. In comparison to the lines 7, 8, the line 4 of the electrohydraulic valve control used for the method according to the invention has a more even course and a smaller pitch, whereby a substantially more accurate adjustment of the charge movement in the cylinder space in the partial load range is possible. In order to fully exploit the resulting benefits to the burn, the range indicated by the limit curves 5 and 6 should not be left. For the desired valve lift hi of the inlet valves, the relationship thus applies:

(0.753 - 0.15) * e ⁰ - ⁰⁰⁷⁸⁷ ^ '- 0.75 <h, ≤ (0.753 + 0.2) * _e ⁰ ' ⁰⁷⁸⁷ '^ + 1 (3)

15 shows schematically the functional principle of an electrohydraulic valve control EHVS suitable for the method according to the invention, as known from DE 101 27 205 A1 or DE 101 34 644 A1, for example, wherein one actuator S is provided per gas exchange valve G. Each actuator S contains essen¬ the hydraulic drive piston K, the upper effective area is about twice the lower effective area, the normally closed 2/2 solenoid valve Vl on the high pressure side and the normally open 2/2 solenoid valve V2 on the low pressure side. The closing lower effective area is constantly and without having a component which is at risk of failure, connected directly to the high pressure generated by the high-pressure pump HP. As long as there is pressure in the hydraulic system, it generates a closing force. In the drawn in Fig. 15 currentless state of the two solenoid valves Vl, V2, the upper hydraulic chamber HKl is separated from the high pressure side and connected to the surge tank AB. To activate the gas exchange valve G two separate electrical operations are necessary. First, the solenoid valve V2 is energized and the outflow of the upper chamber HC1 to the low-pressure side is closed. High pressure is then conducted into the upper hydraulic chamber HK1 by energizing the solenoid valve Vl, and force is built up on the upper effective surface. With reference numeral HK2, the lower hydraulic chamber is referred to, which is always connected to high pressure. With the same high pressure on both active surfaces of the piston K, a resulting hydraulic force is created in the opening direction, corresponding to the surface difference. As soon as existing frictional and gas forces at the gas exchange valve G have been overcome, this is correspondingly accelerated by the resulting force and the mass to be moved. The upper hydraulic chamber HKl increases its volume and hydraulic fluid flows through the solenoid valve Vl.

A shutdown of the solenoid valve Vl and associated with the closing of the high-pressure connection stops the Nachfließen the hydraulic fluid and thus the opening process of the gas exchange valve G. The resulting stroke of Gas¬ interchange valve G results from the metered by means of the solenoid valve Vl, flowed into the upper chamber HKL hydraulic volume. A brief energization of the solenoid valve Vl doses little hydraulic fluid and thus leads only to a small stroke of the gas exchange valve G, a long energization accordingly to a large stroke. Finally, the control of the gas exchange stroke can be attributed to a dosing task with a magnetic valve V 1, similar to an injection.

If solenoid valve V2 continues to remain closed, the actuator S in the case of a closing solenoid valve Vl oscillates in a state of hydraulic equilibrium of forces on the piston K (differential piston) and the gas exchange valve G is in the open state.

The position "gas exchange valve open" is held purely hydraulically until magnetic valve V2 is deactivated and the low-pressure connection opens. Then, the force of the lower active surface, which is still under pressure, pushes the piston K upwards and presses the hydraulic medium from the upper chamber HK1 into the low-pressure line. This process ends with the placement of the gas exchange valve G in the seat, in this position it is still held with hydraulic force. Overall, there is an approximately trapezoidal valve lift curve with slight overshoot at the end of the opening procedure and, depending on the internal hydraulic valve brake used, a sanded transition at the closing end. FIG. 16 shows a stroke h _{G of} the gas exchange valve G over the time t. FIGS. 17 and 18 illustrate the corresponding activation state of the solenoid valves V 1 and V 2, wherein 1 deactivates the activated state and O deactivates Condition designated. With t ₀ is the opening time, with t _c den Schließ¬ time designated. The dotted line shows the state at half maxima ler opening of the gas exchange valve G.

With the electro-hydraulic valve system EHVS the following parameters of the valve control are available:

- The opening crank angle position of each gas exchange valve G is fully variable from cycle to cycle, if necessary, can also be opened several times per clock;

- The closing crank angle position of the individual gas exchange valve G is completely variable from cycle to cycle, if necessary, can also be closed several times per clock;

the stroke of each gas exchange valve G (trapezoidal height) is variable from cycle to cycle;

- The actuating speed and the actuating forces are common for all Gaswechselven¬ tile G by varying the system pressure changeable.

FIGS. 19, 20 and 21 show the valve lift h over the time t for the full load range VL, the partial load range TL and the idling and low-load range LL. The curves h _E denote the exhaust valve lift curve n and hi the inlet valve curves, wherein ti _{c is} the closing time of the intake valves.

The possibility of being able to select the height of the elevation curve of the gas exchange valve G independently of the position of the opening and closing flank makes it possible to set even the smallest loads at high speeds without a throttle flap. At the same time can be optimized by varying the ratio stroke to inlet closing or stroke to opening duration (see Fig. 14).

Claims

PATENT CLAIMS

1. A method for operating an internal combustion engine with at least four Zylin¬ countries with fully variable valve train for at least one input and a Auslass¬ per cylinder (CYL), wherein the internal combustion engine in at least a partial load range (TLL, TL2) with partially disabled cylinders (CYL ) Be¬ is driven, characterized in that the cylinder (CYL) in at least one part load range (TLL, TL2) alternately switched off and reactivated, preferably the shutdown (RI, ZAS, RO) of a deactivated cylinder (CYL ) extends over at least two and maximum three working cycles (A, B, C, D).

2. The method according to claim 1, characterized in that the Ab¬ switching phase (RI, ZAS, RO) of a deactivated cylinder (CYL) each extending over a crank angle range (CA) of at least 1080 ° and at most 2160 °.

3. The method according to claim 1 or 2, characterized in that hochs¬ least three quarters of all cylinders (CYL) is switched off simultaneously.

4. The method according to any one of claims 1 to 3, characterized in that exposed during the shutdown phase (RI, ZAS, RO) the ignition and / or the fuel injection is deactivated.

5. The method according to any one of claims 1 to 4, characterized in that during the shutdown (RI, ZAS, RO) of a cylinder (CYL), des¬ sen inlet and outlet valves are kept predominantly closed.

6. The method according to any one of claims 1 to 5, characterized in that the switch-off (RI, ZAS, RO) of a cylinder (CYL) with the return suction of residual gas through at least one open outlet valve of je¬ respective deactivated cylinder (CYL) is initiated.

7. The method according to any one of claims 1 to 6, characterized in that it shutdown phase (RI, ZAS, RO) of a cylinder (CYL) with the Aus¬ push the residual gas through at least one open exhaust valve of the respective deactivated cylinder (CYL) is completed ,

8. The method according to any one of claims 1 to 7, characterized in that the shutdown and activation of each cylinder (CYL) takes place cyclically.

9. The method according to any one of claims 1 to 8, characterized in that the beginning of the shutdown (RI, ZAS, RO) and the activation of Zy Linder is staggered in time, wherein preferably only one cylinder (CYL) at the same time the shutdown phase (RI, ZAS, RO) begins or ends.

10. The method according to any one of claims 1 to 9, characterized in that each cylinder (CYL) within a certain Kurbelwinkelberei¬ Ches (CA), preferably of at most 3600 °, particularly preferably of 2880 °, at least once turned off and activated.

11. The method according to any one of claims 1 to 10, characterized in that the internal combustion engine in a first partial load range (TLL) in a first Zylinderabschaltmodus (12T) is operated, which essentially essen¬ chen a regular 12-stroke operation, said in Each cylinder (CYL) a work cycle (C) only every 2160 ° crank angle (CA) is performed.

12. The method according to claim 11, characterized in that in the first partial load range (TLL) only about every 540 ° crank angle (CA) performed a power stroke (CA) in at least one of the cylinders (CYL).

13. The method according to claim 11 or 12, characterized in that in the first partial load range (TLL) every 540 ° crank angle in any of Zy¬ cylinder (CYL) starts a shutdown phase (RI, ZAS, RO), wherein the cylinder (CYL) in time staggered according to the firing sequence switched off and acti¬ fourth.

14. The method according to any one of claims 11 to 13, characterized in that in the first part-load range (TLL), the shutdown phase (RI, ZAS, RO) of each deactivated cylinder (CYL) extends over a crank angle range (CA) of about 1440 °.

15. The method according to any one of claims 11 to 14, characterized in that in the first part load range (TLL) always at least two or three cylinders (CYL) are simultaneously deactivated.

16. The method according to any one of claims 11 to 15, characterized in that the first part-load range (TLL) er¬ up to an effective mean pressure (Pm _e ) of at most about 3 bar, preferably up to a maximum of about 2 bar.

17. The method according to any one of claims 1 to 16, characterized in that the internal combustion engine is operated in a second partial load range (TL2) in ei¬ nem second Zylinderabschaltmodus (ZAS2), wherein per Zy¬ cylinder (CYL) between two consecutive shutdown phases (RI , ZAS, RO) two consecutive complete combustion cycles (A, B, C, D) are carried out with a total of two power strokes (C).

18. The method according to claim 17, characterized in that in the second Zylinderabschaltmodus (ZAS2), the shutdown phase (RI, ZAS, RO) of each de¬ activated cylinder (CYL) extends over a crank angle range (CA) of about 1440 °.

19. The method according to claim 17 or 18, characterized in that the cylinder deactivation in two cylinders (1, 4, 2, 3) with overlapping Ab¬ switching phase (RI, ZAS, RO) offset by 360 ° crank angle (CA) is started.

20. The method according to any one of claims 17 to 19, characterized in that the cylinder deactivation at two cylinders (4, 2) with overlapping shutdown phase (RI, ZAS, RO) offset by 900 ° crank angle (CA) is started.

21. The method according to any one of claims 17 to 20, characterized in that the cylinder deactivation at two cylinders (3, 1) with overlapping shutdown phase (RI, ZAS, RO) offset by 1260 ° crank angle (CA) is Begon nen started.

22. The method according to any one of claims 1 to 16, characterized in that the internal combustion engine is operated in a second partial load range (TL2) in ei¬ nem third Zylinderabschaltmodus (ZAS3), wherein per Zylin¬ the (CYL) between two consecutive shutdown phases (RI , ZAS, RO) three consecutive complete combustion cycles (A, B, C, D) are carried out with a total of three power strokes (C).

23. The method according to claim 22, characterized in that in the second Zylinderabschaltmodus (ZAS2), the shutdown phase (RI, ZAS, RO) of each de¬ activated cylinder (CYL) extends over a crank angle range (CA) of about 2160 °.

24. The method according to claim 22 or 23, characterized in that the cylinder deactivation in two cylinders (1, 4, 2, 3) with overlapping Ab¬ switching phase (RI, ZAS, RO) offset by 360 ° crank angle (CA) is started.

25. The method according to any one of claims 22 to 24, characterized in that the cylinder deactivation in two cylinders (4, 2) with overlapping Abschaltphase (RI, ZAS, RO) offset by 1620 ° crank angle (CA) is started nen.

26. The method according to any one of claims 22 to 25, characterized in that the cylinder deactivation at two cylinders (3, 1) with overlapping shutdown phase (RI, ZAS, RO) offset by 1980 ° crank angle (CA) is started begon NEN.

27. The method according to any one of claims 17 to 26, characterized in that in the second partial load range (TL2) in at least one Kurbelwinkelbe¬ empire (CA) three cylinders (CYL) are simultaneously deactivated.

28. The method according to any one of claims 17 to 27, characterized in that in the second partial load range (TL2) in at least one Kurbelwinkelbe¬ empire (CA) two cylinders (CYL) are simultaneously deactivated.

29. The method according to any one of claims 17 to 28, characterized in that at least in a crank angle range (CA) only a single cylinder (CYL) is deactivated.

30. The method according to any one of claims 17 to 29, characterized in that the second partial load range (TL2) subsequent to the first Teil¬ lastbereich (TLL) up to an effective mean pressure (p _me ) to about 3.5 bar to 5, 5 bar, preferably extends to about 4 bar.

31. The method according to any one of claims 1 to 30, characterized in that the internal combustion engine in a subsequent to the first and / or second partial load range (TLL, TL2) third partial load range (TL3) in normal 4-stroke operation (4T) is operated , wherein preferably the ef¬ fective mean pressure (P _me ) in the third part load range (TL3) is greater than in the second and / or first part load range (TLL, TL2).

32. Method for operating an internal combustion engine, wherein the intake and Aus¬ lassventile are operated fully variable, wherein the opening time (ti ₀ ) of the intake valve and the closing time (t _Ec ) of the exhaust valve is changed in dependence of the engine load, characterized in that the internal combustion engine operates in the idling and low-load range (LL) with a slight overlap or undercut of the intake and exhaust valves and in the middle and upper part-load ranges (TL) with greater overlap of the intake and exhaust valves than in the idling and low-load ranges (LL) in the idle and low load range (LL), the intake valves are opened after the top dead center of the charge cycle (OT _LW ) and the exhaust valves in a range between about 300 ° to about 390 ° after the upper dead center of the ignition (OT _Z ) are closed, and wherein in the middle and upper part load range (TL), the intake valves in a range Be¬ between about 270 ° to about 370 ° after top dead center of the ignition (OT ₂ ) opened and the Exhaust valves after the top dead center of the charge cycle (OT _LW ), preferably in a range between about 400 ° to about 540 ° after the top dead center of the ignition (OT ₂ ) are closed ge.

33. Method according to claim 32, characterized in that in the full load range (VL) the internal combustion engine is operated with overlap of the intake and exhaust valves, wherein preferably the overlap is smaller than in the middle and upper part load range (TL) and greater than in Leerlauf¬ and low load range (LL) is, and wherein the inlet valves preferably between about 300 ° and about 380 ° after the top dead center of Zün¬ tion (OTz) open and the exhaust valves in a range of about 330 ° to about 440 ° after the top dead center of the ignition (OT _Z ) are closed.

34. The method according to claim 32 or 33, characterized in that the opening start (t _E o) and opening duration (.DELTA.t _E ) of the exhaust valves are selected so that applies over the entire engine operating range:

t _{£ 0} = 320 * e- ° - ⁰⁰²⁶⁵ ^ ± 45.

35. The method according to any one of claims 32 to 34, characterized in that the idle and low load range (LL) the exhaust valves between 230 ° to about 310 ° crank angle after the top dead center of the ignition (OT ₂ ) are opened, the opening duration ( Δt _E ) of the exhaust valves is about 50 ° to about 130 ° crank angle.

36. The method according to any one of claims 32 to 35, characterized in that the exhaust valves in the middle and upper part load range (TL) in ei¬ nem range between about 130 ° to 270 ° crank angle after the top dead center of the ignition (OT _Z ) are opened wherein the opening duration (Δt _E ) of the exhaust valves is between about 100 ° to about 280 ° crank angle.

37. The method according to any one of claims 32 to 36, characterized in that in the full load range (VL) the exhaust valves in a range between about 70 ° to about 190 ° crank angle after the top dead center of Zün¬ tion (OT ₂ ) are opened, wherein the opening duration (Δt _E ) is between about 260 ° to 430 ° crank angle.

38. The method according to any one of claims 32 to 37, characterized in that the exhaust valves in at least one engine operating point of the partial load and / or idle range (TL, LL) at the earliest at 180 ° crank angle, preferably at the earliest at 200 ° crank angle to the upper Dead center of the ignition (OT ₂ ) to be opened.

39. The method according to any one of claims 32 to 38, characterized in that the exhaust valves are opened in at least one engine operating point of the partial load or idle range over an opening period (.DELTA.t _E ) of a maximum of 240 ° Kur¬ angle.

40. The method according to any one of claims 32 to 39, characterized in that the exhaust valves in at least one engine operating point of Volllast¬ area for an opening duration (.DELTA.t _E ) of at least 340 ° wer¬ opened.

41. Method according to claim 32, characterized in that the intake valves are actuated such that the following relationship between the valve lift Ch ₁ ) and the opening duration (At ₁ ) of the intake valve applies over the entire engine operating range:

(0.753 - 0.1S) V ^{- 00787} ^ '- 0.75 <h, <(0.753 + 0.2) * ^ ⁰⁰⁷⁸⁷ ' * '+ 1.