DE10230935B4 - Operating method for an internal combustion engine with a variable-stroke valve train - Google Patents

Abstract

Operating method for an internal combustion engine with a stroke-variable valve train with at least one gas exchange valve and at least one valve spring, wherein • the stroke height of the gas exchange valve is changed, • the internal combustion engine has a nominal output speed, characterized in that • the stroke height of the gas exchange valve is continuously variable in a vibration-critical speed range of the stroke variable valve train is changed in order to reduce vibration resonance increases and the speed can be increased, the stroke height being changed until the vibration-critical speed range has been overcome, after which the changed valve stroke is reset to a desired valve stroke; then the speed is further increased, whereby • the lifting height is reduced at a speed above the rated power speed and the change in lifting height is read from a map, resonance areas in the valve train also being stored in the map.

Description

The invention relates to an operating method for an internal combustion engine according to the preamble of patent claims 1 and 4, respectively.

Such a method is known from Liebl, J. (et al.): The new BMW four-cylinder gasoline engine with Valvetronic. Part 2: Thermodynamics and functional properties. In MTZ Motortechnische Zeitschrift, 2001, Jg. 62, No. 7/8, pages 570 to 579.

• • DE 197 18 692 C2 ;
• • DE-Fachbuch: Jordan, H.; Greiner, M.: Mechanische Schwingungen. Essen: Verlag W. Giradet, 1952, Seiten 61 bis 70;
• • Heil, B. (u. a.): Verbrauch und Emissionen – Reduzierungskonzepte beim Ottomotor. In: MTZ Motortechnische Zeitschrift, 2001, Jg. 62, Heft 12, Seiten 1022 bis 1035; sowie
• • DE 34 33 934 A1 , US3,602,205 , DE 38 38 915 A1 , DE 198 36 540 A1 , DE 19724921 A1 und DE 69703518 T2 .

The technical background of the present invention also includes:

• • DE 197 18 692 C2 ;
• • DE-Fachbuch: Jordan, H .; Greiner, M .: Mechanical vibrations. Essen: Verlag W. Giradet, 1952, pages 61 to 70;
• • Heil, B. (ua): Consumption and emissions - Reduction concepts for gasoline engines. In: MTZ Motortechnische Zeitschrift, 2001, Jg. 62, No. 12, pages 1022 to 1035; such as
• • DE 34 33 934 A1 . US3,602,205 . DE 38 38 915 A1 . DE 198 36 540 A1 . DE 19724921 A1 and DE 69703518 T2 ,

State of the art

In the DE 42 23 172 C1 is described a valve operation in which the cam of a camshaft via a pivot lever with a control track, which consists of a Leerhubkurve and a lift curve, acting on a gas exchange valve. By pivoting the pivot lever via an adjusting the stroke rate of the zero stroke and the lift curve of the control track is varied. The variation of the stroke of the gas exchange valve is adjusted according to the current requirements of the internal combustion engine. The provision of the pivot lever in the direction of small Gaswechselventilhub via a arranged in the cylinder head spring element. With this arrangement, it is possible to infinitely control the valve lift, which can be dispensed with a throttle valve for load-dependent control of the internal combustion engine.

Another hubvariabler valve drive is from the unpublished German Patent Application 101 23 186 known. In this a valve drive device for variable stroke adjustment of a gas exchange valve of an internal combustion engine is described. In the valve drive device, the gas exchange valve, with the interposition of a transmission element with a movable axis about a rotation axis, in operative connection with a, a Leerhubkurve and a lift curve comprehensive control path, which is arranged in an end region of a lifting operation of the gas exchange valve controlled by a cam of a camshaft pivot lever , The play-free by means of a spring on a roller cam associated with the pivot lever is supported on the other hand for variable stroke adjustment of the gas exchange valve via a controlled by means of an adjustment position adjustable and fixable swing fulcrum along a circular path. To achieve a purely rotational movement or pure pivoting movement of the pivot lever about its oscillating pivot point at a reduced stroke of the gas exchange valve is arranged on a housing part of the engine circular path as a backdrop with a radius "R" about the axis of rotation of the roller of the transmission element for controlled positionally variable support provided the pivot lever. Even with this valve train, it is possible to adjust the lifting height of the gas exchange valve infinitely.

Variable stroke valve trains, as well as conventional valve trains well known to those skilled in the art, are spring mass systems. Further, as is well known, each spring mass system is a vibratory system having at least one vibration resonance peak in which a valve spring no longer exhibits linear behavior. Such resonance peaks can lead to valve spring breaks or uncontrolled valve movements.

task

Object of the present invention is therefore to show an operating method for a generic valve train, which allows a vibration-critical operation.

This object is achieved by the feature in the characterizing part of patent claim 1.

Since the speed of valve trains is limited to high speeds in addition to other limitations by the vibration behavior of the spring mass system, valve spring with other components and gas exchange valve, the speed can be increased to higher speeds out in an advantageous manner by the inventive method. In addition, in all speed ranges of the internal combustion engine, for example, by a chain, or belt control drive in conjunction with the valve train disturbing resonance phenomena occur. With the aid of the operating method according to the invention for the internal combustion engine, all vibration resonance peaks from idle to maximum speed can be reduced. The change of the valve lift can be done in an advantageous manner both in the direction Hubvergrößerung and in the direction Hubverkleinerung. The limits are set by a minimum and a maximum stroke. The free selection of the direction of the stroke adjustment, the adjustment in vibration critical areas can be made such that the driver of the vehicle with the internal combustion engine from the short-term stroke adjustment noticed nothing. An increase in the valve lift leads to a torque or power increase, which can be compensated for example by adjusting an additional throttle. In contrast, a Ventilhubverkleinerung example, be used in the partial load range or in overrun operation of the internal combustion engine. The valve lift can be done in stages or continuously, depending on the actuator used.

In a reduction of the valve lift according to claim 2, in a speed range higher than the rated speed, on the one hand - as already mentioned above - vibration critical areas are advantageously influenced, on the other hand, a targeted power recovery above the rated speed point achievable. This provides the driver of a motor vehicle advantageously direct feedback that the speed of the engine is already very high, as he noticed directly the power loss of the engine. Thus, a continuous operation of the internal combustion engine is avoided in the highest speed range, and pointed to a possible over-rotation of the engine.

The current control of internal combustion engines over at least one characteristic field according to the claims 3 and 4 can be used in an advantageous manner that also resonance areas are stored in the valve train in the map, and thus the correction of the valve directly from a map out.

The valve lift can be done in any manner according to claim 5. Suitable systems are, for example, electrical or hydraulic or pneumatic or mechanical systems or combinations thereof, such as, for example, electromechanical or electrohydraulic systems.

Overall, the operating method according to the invention provides an optimization of the vibration behavior in the valve train, as well as in the control drive, d. H. in conjunction with the valve train with all ancillary units via timing belts or timing chains. In addition, the valve spring design is considerably simplified because vibration-critical speed ranges are advantageously influenced by the variation of the lift height of the gas exchange valve. Furthermore, the operating method leads to a reduction of wear in the valve train, since the reduction of the stroke of the gas exchange valve, the forces occurring in the valve train can be reduced.

In practical operation, an engine control can be designed as follows. After a start of the internal combustion engine, according to the driver instruction on the accelerator pedal, there is an increase in the rotational speed and continuous reading of the operating parameters of the internal combustion engine for their control. When reaching a critical for the valve train speed, changing the Ventilhubs- example map controlled until the critical vibration speed range is overcome, the scheme is such that the driver of this intervention noticed nothing. Then reset the changed valve lift to a Sollventilhub and possibly further speed increase. After reaching the rated speed, reducing the valve lift to reduce the output power of the engine slowly so that the driver gets the achievement of the maximum permissible speed of the engine, without looking at a tachometer, reported back and can switch to the next gear. When reducing the speed, the valve lift is also changed in vibration-critical speed ranges according to the map data.

Claims (4)

Operating method for an internal combustion engine with a variable-stroke valve train with at least one gas exchange valve and at least one valve spring, wherein • the lifting height of the gas exchange valve is changed, • the internal combustion engine has a rated output speed, characterized in that • the lifting height of the gas exchange valve in a vibration critical speed range of the variable-stroke valve drive steplessly is changed in order to reduce vibration resonance increases and increase the speed, wherein the lift height is changed until the vibration critical speed range is overcome, then the changed valve lift is reset to a Sollventilhub; Subsequently, the speed is further increased, wherein • the lifting height is reduced at a speed above the rated speed and wherein the change in the lifting height is read from a map, with resonant areas are stored in the valve train in the map. Operating method for an internal combustion engine according to claim 1, characterized in that the engine is operating point dependent controlled from at least one map. Operating method for an internal combustion engine according to one of the aforementioned claims, characterized in that the Hubverstellung electrically and / or hydraulically and / or pneumatically and / or mechanically. Operating method for an internal combustion engine with a variable-stroke valve train with at least one gas exchange valve and at least one valve spring, wherein the lifting height of the gas exchange valve is changed, the internal combustion engine has a rated speed, characterized in that the lift height of the gas exchange valve in a vibration critical speed range of the variable-stroke valve drive in Stages is changed in order to reduce vibration resonance increases and increase the speed can, wherein the lift height is changed until the critical vibration speed range is overcome, then the changed valve lift is reset to a Sollventilhub; Subsequently, the speed is further increased, wherein • the lifting height is reduced at a speed above the rated speed and wherein the change in the lifting height is read from a map, with resonant areas are stored in the valve train in the map.