DE102010061858A1 - operating procedures - Google Patents

Abstract

The present invention relates to a method for operating an internal combustion engine (1), in particular a motor vehicle, the internal combustion engine (1) in an engine block (2) having several cylinders (3) controlled by gas exchange valves (5, 6) and one of the cylinders (3) Fresh air supplying fresh air system (7) which has at least one additional valve (30) which is arranged in a fresh air duct (8 ', 8' ') leading to at least two cylinders (3) upstream of the associated gas exchange valves (5, 6) which the respective additional valve (30) is operated in such a way that opening phases (A), in which the additional valve (30) opens the fresh air duct (8 ', 8' '), and closing phases (B), in which the additional valve (30) the fresh air duct (8 ', 8' ') closes, alternate, in which the respective additional valve (30) is also operated so that it generates a separate opening phase (A) for each associated cylinder (3). Improved efficiency can be achieved if the respective additional valve (30) is operated in such a way that it generates opening phases (A) of different sizes for the associated cylinders (3), which follow one another directly.

Description

The present invention relates to a method for operating an internal combustion engine, in particular a motor vehicle.

Internal combustion engines come stationary, z. As in emergency generators or combined heat and power plants, or in mobile uses such. As in aircraft, watercraft and land vehicles, especially road vehicles and off-road vehicles.

Usually, an internal combustion engine comprises an engine block which contains a plurality of cylinders, in each of which a piston is arranged such that it can be adjusted in terms of stroke, so-called piston engine or reciprocating engine. Gas exchange processes of these cylinders are controlled by means of gas exchange valves, ie with inlet valves and exhaust valves. To supply the cylinders with fresh air, the internal combustion engine is usually equipped with a fresh air system which comprises at least one fresh air duct, which simultaneously supplies several cylinders with fresh air. By way of example, such a fresh air duct comprises a fresh air distributor, from which individual connecting pipes exit to one cylinder each.

In order to improve the fresh air loading of the cylinder and to control a return of exhaust gas, it is basically possible to arrange in the fresh air system upstream of the gas exchange valves, so in addition to the gas exchange valves at least one additional valve in the fresh air system, with the help of the respective fresh air duct can be opened and closed. Such an additional valve operates dynamically and thus differs fundamentally from a throttle valve, which may be provided in conventional combustion engines in the fresh air system to throttle at low loads, the fresh air supply. With the help of such additional valves, it is in principle possible to generate pressure pulsations in the air flow leading to the cylinders or to intensify existing pressure pulsations due to the gas exchange processes. In this case, positive pressure pulses, which lead to pressure increases, can be used to supply the individual cylinders more air mass, so-called impulse charging. It is likewise possible to generate negative pressure pulses which lead to pressure drops in order to improve exhaust gas recirculation or specifically to set an exhaust gas recirculation rate.

Additional valves for controlling the exhaust gas recirculation are for example from the DE 10 2006 028 146 A1 , from the DE 10 2006 037 934 A1 and from the DE 10 2007 004 264 A1 known.

Furthermore, it is for example from the DE 10 2008 036 494 A1 to coordinate such additional valves with intake valves of the cylinder so that the temperature during the combustion process, ie the respective process temperature is lowered to reduce pollutant emissions, especially NOX emissions. For example, the so-called Miller process or the so-called Atkinson process can be carried out with the aid of the additional valves. In the Miller process, the loading process of the respective cylinder is terminated earlier than usual, namely before the bottom dead center of the associated piston. In the Atkinson process, the loading process is prolonged, namely until after the bottom dead center of the respective piston. In both cases, the total amount of fresh air supplied to the cylinder is reduced, which leads to a reduction in pressure in the combustion process and thus to a drop in temperature.

From the WO 2010/007026 A1 Another additional valve is known, which is equipped with a phaser, with the aid of the phase position between the actuator and the valve member can be varied.

According to the DE 10 2009 020 171 It is also known to use the respective additional valve that in individual operating points of the internal combustion engine, an environmental parameter of the internal combustion engine is optimized or that for at least two environmental parameters of the internal combustion engine, an optimized compromise is set. This is achieved by varying a phase angle of the respective additional valve relative to the rotation of a crankshaft of the internal combustion engine or relative to its crankshaft angle.

In order to be able to generate the different flow dynamic effects, the respective additional valve is usually operated such that opening phases in which the additional valve opens the fresh air duct and closing phases in which the additional valve closes the fresh air duct alternate. If such an additional valve is assigned to a plurality of cylinders, that is to say arranged in a fresh-air duct which leads to a plurality of cylinders, the additional valve is expediently operated such that it generates separate opening phases for each assigned cylinder. For example, the respective fresh air duct lead to three cylinders of the internal combustion engine, so that the additional valve is then assigned to three cylinders. In a six-cylinder engine, which operates on the four-stroke principle, the firing order of the individual cylinders can be tuned so that the respective additional valve associated three cylinders are sequentially clocked in phase, so with respect to the crankshaft angle to each other, in particular the Suction cycles of the cylinders separated in time from each other and occur one after the other. This makes it possible that with the help of an additional valve for each associated cylinder, a separate opening phase can be generated.

The present invention is concerned with the problem of providing for an operating method of the type mentioned in an improved embodiment, which is characterized in particular by the fact that the energy efficiency of the internal combustion engine is improved, in particular pollutant emissions to be reduced.

This problem is solved according to the invention by the subject matter of the independent claim. Advantageous embodiments are the subject of the dependent claims.

The invention is based on the general idea of using the additional valve to optimize the opening phases individually in terms of their length or in terms of their duration for the respective cylinder. This is achieved, in which the additional valve is operated so that it generates different sized opening phases for the associated cylinder, which follow one another directly. Thus, if the respective additional valve, for example, three cylinders are assigned, the additional valve generates during a complete cycle of the internal combustion engine, ie during two complete revolutions of the crankshaft, ie within 720 ° crankshaft angle (short "KWW" or "KW") exactly three opening phases are spaced apart by closing phases, wherein these three opening phases are different in size, so extend over different angular ranges of crankshaft rotation.

The invention takes into account the knowledge that within the fresh air channel for each associated cylinder, a separate flow path is present, which leads from the common auxiliary valve to the respective cylinder or to the combustion chamber. Due to design needs, these flow paths are not identical. For example, one flow path may be longer than another. Additionally or alternatively, one flow path may contain more flow deflections than another. Additionally or alternatively, one flow path may include more flow obstacles and / or flow resistances than another. This leads in the end to equal opening times of the additional valve to different loads or - depending on the purpose of the additional valve - lead to different exhaust gas recirculation rates in the individual cylinders. It has thus been shown that identical opening phases of the common additional valve at the associated cylinders lead to an inhomogeneous supply of fresh air or recirculated exhaust gas. The proposal according to the invention of selecting the opening phases differently for the different cylinders now results in the possibility of homogenizing the supply of the associated cylinders with fresh air or with recirculated exhaust gas. For example, a smaller opening phase can be selected for a cylinder that is coupled to the auxiliary valve via a shorter fresh air path, while a larger opening phase can be selected for a cylinder that is coupled to the additional valve via a fresh air path provided with a plurality of flow diversions. Through experiments, the optimum opening phases for the different cylinders can be determined in order to more or less compensate for the design-related deviations of the fresh air paths.

The achievable with the aid of the operating method according to the invention homogenization of the supply of individual cylinders with fresh air or with recirculated exhaust gas can reduce the pollutant emissions and / or fuel consumption.

According to an advantageous embodiment, the respective additional valve may have a permanently rotating valve member which at least completes a closing angle range forming such a closing phase and at least one opening angle range forming such an opening phase, wherein the rotational speed of the valve member is changed to change successive opening phases. In other words, in order to be able to vary the successive opening phases in terms of their duration in an additional valve with a permanently rotating valve member, the additional valve is designed so that the rotational speed at which the valve member rotates, can be changed dynamically, ie during one revolution of the valve member , in particular between two consecutive closing phases and in particular within an opening phase. This can be realized in particular by means of an electric motor drive, for example by means of a brushless DC motor.

According to another advantageous embodiment, the respective additional valve can be actuated so that the opening phases have a predetermined phase position to the crankshaft angle of a crankshaft of the internal combustion engine in a stationary operating state of the internal combustion engine. For example, it may be important for the respective positive or negative pressure pulse to arrive in the region of a predetermined crankshaft angle at the respective cylinder, for example immediately before the closing of the associated intake valve or the associated intake valves. The changing of the opening phases can then be carried out so that in a steady-state operating state of Internal combustion engine, the predetermined phase position is maintained to the crankshaft angle of the crankshaft. For example, an opening phase can be increased by reducing the preceding and / or the subsequent closing phase, in such a way that a period duration remains constant. In the event that an opening phase is to be reduced, the preceding and / or the subsequent closing phase can be increased, such that the period duration remains constant. The respective period is defined by the time interval between the centers of two successive opening phases.

In another advantageous embodiment, the respective additional valve can be used to control an exhaust gas recirculation rate. In the closing phases, a negative pressure can be generated or increased at a downstream of the additional valve inlet point for recirculated exhaust gas, whereby the amount of recirculated exhaust gas can be influenced. The exhaust gas recirculation rate behaves antiproportional to the opening phase of the additional valve. The larger the opening phase, the greater the exhaust gas recirculation rate and vice versa.

According to another advantageous embodiment, the fresh air passage from the respective additional valve to the associated cylinders may have different flow paths which would lead to differences in the fresh air filling and / or exhaust gas recirculation rate at the respective cylinder, wherein the different opening phases are adapted to the different flow paths, that the mentioned differences are reduced, in particular eliminated. In this embodiment, the potential of the present invention is optimally utilized to homogenize the supply of the individual cylinders with respect to fresh air and / or recirculated exhaust gas.

According to a particularly advantageous embodiment, the respective additional valve with the help of an electric motor, such as. Example, a brushless DC motor, permanently rotating driven valve member, wherein the electric motor is driven to generate varying rotational speeds during a revolution of the valve member with a continuous drive function. The use of a continuous drive function reduces the load on the electric motor and allows reliable control times.

The control function used in this case can be the product of at least two continuous sub-functions according to an advantageous embodiment. Suitably, the respective subfunction may each include a sine function. In particular, a first partial function may be a sine function of the first power, while a second partial function may be a sine function of the third power. Suitably, the zero crossing of the first partial function with negative derivative can be set to the middle of the opening phase of the additional valve. It is particularly advantageous to set the maximum of the second partial function to the middle of the opening phase of the additional valve. It has been shown that such a drive function leads to a particularly favorable course of the rotational movement of the valve member, with which the varying opening times can be represented in a particularly simple and reliable manner.

Particularly advantageous is an embodiment in which the fresh air system downstream of the respective additional valve up to the gas exchange valves and upstream of the respective additional valve contains no controllable throttle. In other words, the fresh air system is operated unthrottled or throttle-free. The fresh air supply to the cylinders is controlled exclusively via the respective additional valve. In particular, thus, the loading control for the cylinder can be realized by means of the additional valve. Particularly useful is an embodiment in which the respective additional valve is operated both for loading control of the associated cylinder as well as for controlling an exhaust gas recirculation rate to the individual cylinders.

It has proven particularly advantageous if, in a 4-stroke engine for every three cylinders, a single additional valve is used which is assigned to these three cylinders. In particular, therefore, only a single additional valve can be provided in a 3-cylinder engine. In contrast, in the case of a 6-cylinder engine, precisely two such additional valves may be provided, which are then assigned to three cylinders each.

According to another advantageous embodiment, it can be provided that the opening phases are varied depending on a current operating state of the internal combustion engine in order to adapt the opening phases to the current operating state of the internal combustion engine. It is expedient to vary the opening phases for adaptation to the current operating state of the internal combustion engine such that an opening duration of the respective opening phase measured in degrees crankshaft angle of a crankshaft of the internal combustion engine is varied, for which a closing time of the opening phase is varied with respect to its phase angle to the crankshaft angle during an opening time the opening phase remains constant with respect to its phase angle to the crankshaft angle.

This embodiment is based on the general idea of varying the Opening phases in the context of adaptation to different operating conditions of the internal combustion engine to shift only the closing time and to leave the opening time constant. To increase the opening phases thus only the closing time is moved to late, while only the closing time is moved to shorten the opening phases to early. This measure is based on the surprising finding that, for an optimal compromise between fuel consumption and pollutant emissions, in particular NOX emissions, there is a time window in which the opening time for the opening phases must lie, this time window being independent of the operating state of the internal combustion engine and independent of the Size of the opening phase is, even if the size of the opening phase has a strong dependence on the operating condition of the internal combustion engine. However, the position of this time window may depend on the respective pursued operating strategy, after which the internal combustion engine is to be operated, for. B. optimized for pollutants, optimized for fuel consumption, performance optimized etc.

According to an advantageous embodiment, the respective additional valve may have a permanently rotating valve member which at least completes a closing angle range forming such a closing phase and at least one opening angle range forming such an opening phase, the rotational speed of the valve member varying within a complete revolution to vary the closing time is so that during the opening phases other rotational speeds are present than during the closing phases.

For example, in order to shorten the opening duration, the rotational speed can then be increased during the opening phase and reduced in the closing phase, such that the phase position of the opening time to the crankshaft angle remains constant. By keeping constant the phase position of the opening time, the change in the opening period is based solely on a shift of the closing time. The same applies to increasing the opening duration, which is achieved by reducing the rotational speed during the opening phase and increasing it in the closing phase, such that the phase angle of the opening time to the crankshaft angle remains constant.

According to a specific embodiment, the opening time of the opening phase of the respective additional valve coincide regardless of the operating condition of the internal combustion engine with a controlled by the gas exchange valves inlet start for the respective cylinder or a maximum of 10 ° crankshaft angle or a maximum of 5 ° crankshaft angle. Such a relationship between the opening time and the start of intake can be observed for a predetermined operating strategy, for example, to optimize low fuel consumption with low pollutant emissions. In another operating strategy, for example, should lead to a rapid warm-up of the internal combustion engine, of course, other relationships between the opening time and the beginning of intake can be selected. For example, other relationships between the opening time and the beginning of the intake may be relevant for the heat charge mentioned at the outset (Miller method or Atkinson method).

Other important features and advantages of the invention will become apparent from the dependent claims, from the drawings and from the associated figure description with reference to the drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

Preferred embodiments of the invention are illustrated in the drawings and will be described in more detail in the following description, wherein like reference numerals refer to the same or similar or functionally identical components.

Show, in each case schematically,

1 a greatly simplified schematic diagram of an internal combustion engine,

2 an isometric view of an additional valve,

3a a highly simplified, schematic longitudinal section of the additional valve,

3b a diagram for illustrating the opening behavior of the additional valve depending on a rotation angle of a valve member,

4 a diagram for illustrating different opening phases of the additional valve,

5 a diagram illustrating successive, different opening phases for three cylinders,

6 3 is a diagram illustrating successive different opening phases in a 6-cylinder engine;

7 to 14 each a simplified longitudinal section of the additional valve (a), a schematic diagram of the internal combustion engine with three cylinders (b) and a course diagram for a four-stroke operation of the three cylinders, depending on the crankshaft angle (c), at different times or crankshaft angles,

15 several diagrams (a) to (f) for illustrating different opening phases at different operating conditions of the internal combustion engine.

Corresponding 1 includes an internal combustion engine 1 how they z. B. in a motor vehicle can be used, for. B. an engine block 2 , the several cylinders 3 contains, each a combustion chamber 4 enclose and in each of which an unspecified piston is arranged strokeverstellbar. Other engine configurations, such as the boxer engine, V-engine and W-engine, are a matter of course. In the example, only six such cylinders are purely exemplary and without restriction of generality 3 arranged in a row. Every combustion chamber 4 or each cylinder 3 are gas exchange valves, namely inlet valves 5 and exhaust valves 6 assigned in the engine block 2 are arranged. In the example is per combustion chamber 4 or per cylinder 3 an inlet valve 5 and an exhaust valve 6 intended. It is clear that even two or more intake valves 5 or two or more exhaust valves 6 per cylinder 3 can be provided. The internal combustion engine 1 is preferably for use as a vehicle drive for commercial vehicles and passenger cars, useful in heavy commercial vehicles such. As construction vehicles and off-road vehicles. In principle, however, is also a use of the internal combustion engine 1 in other vehicles, such. As watercraft or in stationary facilities conceivable.

The internal combustion engine 1 has a fresh air system 7 on, which is used to supply fresh air to the combustion chambers 4 or to the cylinders 3 serves. For this purpose, the fresh air system 7 a fresh air line 8th on that a fresh air path 9 contains in 1 indicated by arrows. In addition, the internal combustion engine 1 with an exhaust system 10 equipped, which serves to exhaust gases from the combustion chambers 4 lead away. For this purpose, she has an exhaust pipe 11 that have an exhaust path 12 contains, which is indicated by arrows. In addition, the internal combustion engine 1 with an exhaust gas recirculation system 13 equipped with which it is possible exhaust gases from the exhaust system 10 to the fresh air system 7 due. For this purpose has the exhaust gas recirculation system 13 at least one return line 14 , In the example are two such return lines 14 intended. Every return line 14 leads from a branch point 15 to a discharge point 16 , At the respective branch point 15 is the return line 14 on the input side with the exhaust pipe 11 connected. At the respective discharge point 14 is the respective return line 14 on the output side with the fresh air line 8th connected.

In the example is the fresh air system 7 at least in one to the combustion chambers 4 to the cylinders 3 subsequent section designed two-way, so that the fresh air line 8th a first flood in this area 8th' to supply the first three cylinders 3 or the first three combustion chambers 4 or a second flood 8th'' which is used to supply the second three cylinders 3 or the second three combustion chambers 4 serves. The first flood 8th' and the second flood 8th'' in each case form a fresh air channel, which in the following also with 8th' respectively. 8th'' referred to as.

Analogous to the fresh air system 7 is also the exhaust system 10 at least in one to the cylinder 3 or to the combustion chambers 4 subsequent section designed two-way, so that the exhaust pipe 11 at least in one to the cylinder 3 or to the combustion chambers 4 subsequent section one of the first three cylinders 3 assigned first tide 11 ' and one of the second three cylinders 3 associated second tide 11 '' having.

The two exhaust gas recirculation lines 14 are accordingly each one of these floods 8th' respectively. 8th'' respectively. 11 ' respectively. 11 '' assigned. In particular, at each fresh air duct 8th' . 8th'' such an exhaust gas recirculation line 14 connected. In the example, each return line is also 14 with an exhaust gas recirculation cooler 17 fitted.

Furthermore, the internal combustion engine 1 charged in the example shown, so that at least one charging device is provided. In the example, two charging devices are provided, namely a first charging device 18 and a second charging device 19 , Both charging devices 18 . 19 are designed in the example as exhaust gas turbocharger. Accordingly, the first charging device comprises 18 a first compressor 20 who in the fresh air pipe 8th is arranged, and via a first drive shaft 21 with a first turbine 22 drive connected, which is in the exhaust pipe 11 is arranged. The second charging device 19 accordingly comprises a second compressor 23 who in the fresh air pipe 8th is arranged and via a second drive shaft 24 with a second turbine 25 drive connected, which is in the exhaust pipe 11 is arranged. Here is the second compressor 23 downstream of the first compressor 20 arranged while the second turbine 25 upstream of the first turbine 22 is arranged. Between the first compressor 20 and the second compressor 23 is a first intercooler 26 in the fresh air line 8th arranged. Between the second compressor 23 and the cylinders 3 is a second one Intercooler 27 in the fresh air line 8th arranged.

A corresponding exhaust gas recirculation flow is indicated by arrows 28 indicated. In the example of 1 is in every return line 14 also an exhaust gas recirculation valve 29 arranged, with the help of the respective return line 14 can be opened or locked and which can be used in particular for setting an exhaust gas recirculation rate.

The internal combustion engine 1 is also with at least one additional valve 30 fitted. In the example are two such additional valves 30 intended. The respective additional valve 30 is in the fresh air system 7 upstream of the gas exchange valves 5 . 6 So here upstream of the intake valves 5 arranged. In the example is the two floods 8th' . 8th'' in each case such an additional valve 30 assigned. That is, in every fresh air channel 8th' . 8th'' is in each case such an additional valve 30 arranged. Thus, in the example, each additional valve 30 three cylinders each 3 or three combustion chambers 4 assigned.

According to 2 can such an additional valve 30 an electric motor 31 as drive to the respective additional valve 30 for opening and closing the respective fresh air duct 8th' respectively. 8th'' to be able to press. In the example, the additional valve includes 30 a line section 32 with which the additional valve 30 in the respective fresh air duct 8th' respectively. 8th'' the fresh air system 7 can be integrated. The additional valve 30 Contains in the associated channel section 32 a valve member 33 , which is formed in the example by a flap, which may be referred to in particular as a butterfly flap. The valve member 33 is rotatable on a shaft 34 arranged with the electric motor 31 is drive connected. The electric motor 31 is preferably designed such that it the valve member 33 can drive to a permanent rotation. The speed of the drive 31 or the valve member 33 can, for example, in a substantially fixed relation to a speed of an in 1 indicated crankshaft 35 the internal combustion engine 1 stand.

The 2 and 3a show a useful example of an additional valve 30 , which is a permanently rotating valve member 33 having. 3b illustrates the course of the valve member 33 controlled through-flow cross-section of the fresh air channel 8th' respectively. 8th'' depending on the angle of rotation φ of the valve member 33 , The respective opening phase A is designated within the course curve A, while the closing phases adjacent thereto are designated B.

At one complete revolution of this valve member 33 this passes through at least one closing angle range β and at least one opening angle range α. The respective closing angle range β defines a closing phase B of the additional valve 30 while the respective opening angle range α an opening phase A of the additional valve 30 forms. During the opening phase A, the additional valve opens 30 or its valve member 33 the fresh air duct 8th' respectively. 8th'' , During the closing phases B, the additional valve closes 30 or its valve member 33 the respective fresh air duct 8th' respectively. 8th'' , In the example shown has the additional valve 30 at a complete revolution of the valve member 33 exactly two opening phases A and two closing phases B, which alternate.

To form significant closing angle ranges β has a channel wall 36 wells 37 into which the valve member 33 immersed in its rotation. The wells 37 For example, are profiled in a circle segment shape and have a diameter D which is greater than a height H of the respective channel 8th' respectively. 8th'' respectively. 32 and the width of the valve member measured substantially transverse to the axis of rotation 33 equivalent.

With the help of a 1 indicated control 38 , in a suitable way with the respective additional valve 30 connected, can be the respective additional valve 30 So operate it for each assigned cylinder 3 creates a separate opening phase A.

This means that the respective additional valve 30 on the gas exchange operations according to the four-stroke principle of the associated three cylinders 3 is tuned so that in each case an intake stroke of the respective cylinder 3 an opening phase A can be assigned.

The respective additional valve 30 will now be using the controller 38 so operated it for the associated cylinder 3 different opening phases A can produce, these differently sized or different length of opening phases A can follow each other directly.

For example, shows 4 two examples of different opening phases A. A shorter or smaller opening phases A _{1 can be seen} , which extends in a crankshaft angle range from about 60 ° KWW to about 180 ° KWW. Furthermore, a larger or longer opening phase A _{2 can be seen} , which extends for example in a crankshaft angle range of approximately 40 ° KWW to approximately 200 ° KWW. As a comparison, in the diagram of the 4 a sinusoidal curve E of an intake valve 5 registered, whose opening time window ranges from about 0 ° KWW to about 240 ° KWW.

5 shows how differently sized opening phases A in the successive loading phases of the successive, located in the intake stroke cylinder 3 follow one another. For example, the three can be the respective additional valve 30 associated cylinder 3 due to their distance to the additional valve 30 differ from each other. For example, has a first cylinder 3 , the greatest distance to the additional valve 30 , a second cylinder 3 ₂ has a mean distance to the additional valve 30 and a third cylinder 3 ₃ has the smallest distance to the additional valve 30 , For orientation, the indexed reference numbers are also in 1 entered to the individual cylinders 3 in terms of their distance from the respective additional valve 30 to characterize.

According to 5 will the three cylinders 3 ₁ , 3 ₂ and 3 ₃ with the help of a common additional valve 30 each associated with a separate opening phase A, wherein the successive opening phases A differ from each other in terms of their length or duration. This is how the first cylinder gets 3 _1, the largest opening phase A ₁ during the third cylinder 3 ₃ the smallest opening phase A _{3 is} metered. The second cylinder 3 ₂ receives a medium opening phase A ₂ . It is noteworthy that in this case the opening time window E of the intake valves 5 stay the same size.

6 shows now purely by way of example the sequence of the different opening phases A in the six cylinders of the six-cylinder engine of 1 , The one generates according to 1 lower additional valve 30 in the 6 shown below three different successive opening phases A ₁ , A ₂ and A ₃ for the three in 1 Bottom-mounted cylinders 3 ₁ , 3 ₂ and 3 ₃ , while the other according to 1 upper additional valve 30 for the in 1 shown above three cylinders 3 ₁ , 3 ₂ and 3 ₃ generates the various opening phases A ₁ , A ₂ and A ₃ . Visible results between the opening phases A of an additional valve 30 and the opening phases A of the other additional valve 30 a phase shift of about 120 ° KWW, which is due to the firing order of the six-cylinder four-stroke engine.

The 7 to 14 Now illustrate the interaction of the different working cycles of the three cylinders 3 that the one additional valve 30 assigned. The subfigures show 7a to 14a each additional valve 30 in a longitudinal section in a simplified representation, wherein here it is important to distinguish the closing phases B and the opening phases A from each other. The subfigures 7b to 14b illustrate the gas flow. The subfigures 7c to 14c illustrate the relation of the respective state with respect to the rotation of the crankshaft 35 , Two complete revolutions of the crankshaft 35 , ie 720 ° KWW or KW correspond to a duty cycle or cycle of the internal combustion engine 1 ,

In the subfigures 7c to 14c are the different bars of each cylinder 3 according to the four-stroke principle, namely as "suction" for the intake stroke, "compression" for the compression stroke, "combustion" for the combustion cycle and "pushing out" for the Ausschiebetakt.

It is noteworthy that in the present case, the respective additional valve 30 is used to control an exhaust gas recirculation rate. Accordingly, in the 7a to 14a the discharge point 16 recognizable, via the recirculated exhaust gas in the respective fresh air duct 8th' respectively. 8th'' or in the line section 32 can be initiated. Accordingly, also in the 7b to 14b the respective return line 14 recognizable.

In the state according to 7 starts the viewing at 0 ° KW. The additional valve 30 is at a rotation angle φ of 0 ° and generates a closing phase B. The first cylinder 3 ₁ is in the intake stroke, the second cylinder 3 ₂ is in the compression stroke and the third cylinder 3 ₃ is in the combustion cycle. In this state, the first cylinder 3 ₁ reinforced exhaust gas supplied, as by the closing phase B of the additional valve 30 the supply of fresh air is interrupted.

8th shows a condition at 120 ° KW. Now there is the additional valve 30 at a rotational angle φ of 90 ° and generates an opening phase A, so that the first cylinder 3 _{1 is} now increasingly supplied with fresh air. The second cylinder 3 ₂ is here at the transition to the combustion cycle. The third cylinder 3 ₃ is in the Ausschiebetakt.

9 now shows the state at 240 ° KW. The additional valve 30 is at a rotation angle φ of 180 ° and generates a closing phase B. Consequently, it is now about the supply of the third cylinder 3 ₃ with exhaust.

In 10 the system is at 360 ° KW. The additional valve 30 shows a rotation angle φ of 270 ° and is open. This is about the supply of the third cylinder 3 ₃ with fresh air.

In 11 becomes now at 480 ° KW and φ = 360 ° the second cylinder 3 ₂ supplied with exhaust gas.

According to 12 becomes the second cylinder at 600 ° KW and φ = 90 ° 3 ₂ supplied with fresh air.

at 13 the system is in the state of 720 ° KW (φ = 180 °), so now two complete revolutions of the crankshaft 35 are completed. The condition according to 13 therefore corresponds identically to the state according to 7 ,

Another 120 ° KW (φ = 270 °) later shows the state according to 14 that out of the state 8th equivalent.

It is noteworthy that the speeds of crankshaft 35 and valve member 33 according to a ratio of 4: 3 move each other.

In order to be able to vary the opening phases A in terms of their size or in terms of their duration, is the rotating valve member 34 provided, the rotational speed of the valve member 34 to change, and that dynamic, so within a single revolution of the valve member 33 , If the valve member 33 As in the examples shown here during a complete revolution has two opening phases A and two closing phases B, the rotational speed of the valve member 33 be varied so that within a single revolution, two different opening phases A can be realized.

How the 4 to 6 can be removed, the respective additional valve 30 are suitably operated so that the opening phases A a predetermined phase position to the crankshaft angle of the crankshaft 35 exhibit. For example, located in 4 the vertex of the respective curve of the opening phase A at about 120 ° KWW and at 5 approximately in the middle of the elevation curve E of the respective inlet valve. Also 6 It can be seen that successive opening phases A each have the same distance with respect to their vertices or their centers or centers, namely 240 ° KWW.

The changing of the opening phases A can thus preferably be carried out so that the predetermined phase angle to the crankshaft angle is maintained.

To increase the opening phase A, it is therefore possible to reduce both the preceding and the subsequent closing phase B, in such a way that a period remains constant. The respective period is measured, for example, by the time interval or the crankshaft angle between the centers of two successive opening phases A. In the examples shown here, this period is about 240 ° KWW. If the opening phase A is to be reduced, it may be expedient to increase the preceding and the subsequent closing phase B, such that the period duration remains constant.

As mentioned, in the example shown, the respective additional valve 30 used to control the exhaust gas recirculation rate. The longer the closing phase B lasts, the more exhaust gas can be sucked in or returned. If the respective additional valve 30 can be used to control the exhaust gas recirculation rate, can basically on the in 1 shown return valves 29 be waived.

The different opening phases A take into account the different flow paths of the respective additional valve 30 to the respective cylinder 3 ₁ , 3 ₂ , 3 ₃ and reduce resulting asymmetries with respect to the supply of the respective cylinder 3 with fresh air or with recirculated exhaust gas.

If, as in the example shown, the respective additional valve 30 with the help of an electric motor 31 is driven, can be provided according to a particularly advantageous embodiment, the electric motor 31 with a continuous drive function f (x) to control. This drive function f (x) is expediently the product of at least two continuous subfunctions g (x) and h (x). The two subfunctions g (x) and h (x) are in particular sine functions. The first partial function g (x) is for example a sine function of the first power, while the second partial function h (x) can be, for example, a sine function of the third power. Particularly advantageous is now a design in which the zero crossing of the first partial function g (x) with negative derivative to the center of the opening phase A of the additional valve 30 is set. At the same time, the maximum of the second partial function h (x) becomes the center of the opening phase A of the additional valve 30 set. The proposed design of the drive function f (x) allows a particularly harmonic course for the valve member 33 realize.

Like yourself 1 can be removed, owns the fish air system 7 downstream of the respective additional valve 30 to the gas exchange valves 5 . 6 and upstream of the respective additional valve 30 no controllable throttle. In that regard, the fresh air system 7 unthrottled or throttle-free designed. The loading control of the individual cylinders 30 can with the help of the respective additional valve 30 be realized, namely by the appropriate dimensioning of the opening phases A.

While the above description is largely based on stationary operating conditions of the internal combustion engine 1 turns off, in which in particular constant rotational speeds and / or the same power from the internal combustion engine 1 The description below relates to the behavior of the controller 38 or the adaptation of the opening phases A at different operating conditions. Depending on the operating state it can namely be necessary to change the opening phases A in terms of their length, for example, to achieve optimal fuel consumption and pollutant emission for the respective operating condition. In principle, the above individualization of the opening phases A for the individual cylinders 3 disregarded. However, an embodiment is preferred in which during a stationary operating state the same additional valve 30 associated cylinders 3 different opening phases are metered and in which the changeover phases between two stationary operating states, the opening phases A can be varied.

In other words, the cylinder-specific or local variation of the opening phases A is used to homogenize the supply of fresh air or of recirculated exhaust gas with respect to the individual cylinders 3 , The general or global variation of the opening phases A serves to adapt the opening phases A of all cylinders 3 to changing operating conditions of the internal combustion engine 1 , These two different variations (global or local) can basically be considered separately. However, preferred is a combined consideration, so that the respective control 38 even with changing operating conditions and associated globally varied different opening phases A, the local variation for the homogenization of the supply of the individual cylinders 3 realized with fresh air or recirculated exhaust gas by appropriately adapting the opening phases A.

In order now to open the phases A for adaptation to the current operating state of the internal combustion engine 1 can vary as explained, the opening duration of the respective opening phase A can be changed. For this purpose, in principle, an opening time and a closing time of the additional valve 30 move. Particularly expedient, however, is a procedure in which, with respect to its opening duration, the closing time of the opening phase A is varied with respect to its phase angle to the crankshaft angle for varying the opening phases A, while the opening time of the opening phase A is kept constant with respect to its phase angle to the crankshaft angle. It has been found that this procedure is particularly advantageous with regard to the achievable values for fuel consumption and pollutant emissions.

The 15a to 15f show survey curves E for intake valves 5 and survey curves V for exhaust valves 6 , Further, the closing phases B and the opening phases A of the additional valve 30 recognizable. Furthermore, each diagram contains 15a to 15f a vertical line 39 , which represents the opening time of the opening phase A, the intake stroke of the respective cylinder 3 assigned. It also defines a vertical line 40 the closing time at which the respective opening phase A is completed. An opening period 41 then results from the difference of closing time 40 and opening time 39 ,

The 15a to 15f Now show a sequence of different operating conditions of the internal combustion engine 1 , each with different opening times 41 require. In the sequence of diagrams of 15a to 15f takes said opening period 41 from. This is the closing time 40 shifted towards smaller crankshaft angles during the opening time 39 remains constant.

According to an advantageous embodiment, the respective additional valve 30 a permanently rotating valve member 33 have, during a complete revolution, at least one closing angle range β forming such a closing phase B and at least one opening angle range α forming such an opening phase A, wherein for varying the closing time point 40 the rotational speed of the valve member 33 is varied within a complete revolution, so that different rotational speeds are present during the opening phases A than during the closing phases B.

For example, then can shorten the opening time 41 the rotational speed is increased during the opening phase A and reduced in the closing phase B, such that the phase position of the opening time point 39 remains constant to the crankshaft angle. By keeping constant the phase position of the opening time 39 the change in opening duration is due 41 solely on a shift of the closing time 40 , The same applies to increasing the opening duration 41 , which is achieved in that the rotational speed is reduced during the opening phase A and increased in the closing phase B, such that the phase position of the opening time point 39 remains constant to the crankshaft angle.

According to a specific embodiment may for the respective cylinder 3 the opening time 39 the opening phase A of the respective additional valve 30 regardless of the operating state of the internal combustion engine 1 with one through the gas exchange valves 5 . 6 controlled inlet start (beginning of the elevation curve E of the intake valve 5 ) coincide or at most have a distance of 10 ° crankshaft angle or at most a distance of 5 ° crankshaft angle. Such a connection between opening time 39 and start of intake may be required for a predetermined operating strategy, For example, to optimize low fuel consumption with low pollutant emissions. In another operating strategy, for example, to a rapid warm-up of the internal combustion engine 1 Of course, other connections between the opening time 39 and inlet beginning to be selected. For example, for the aforementioned heat load (Miller method or Atkinson method) other relationships of opening time 39 and the beginning of the entry.

The variation of the opening phases A proposed here for adaptation to changing operating states by shifting the closing time 40 and keeping the opening time constant 39 can in fresh air systems 7 be carried out for each cylinder 3 a separate additional valve 30 exhibit.

According to the embodiment shown here, the respective fresh air duct 8th' . 8th'' in which the respective additional valve 30 is arranged to several cylinders 3 lead, so that respective additional valve 30 several cylinders 3 is assigned, for which it generates separate opening phases A respectively. Because such an additional valve 30 can operate with high dynamics and drive, it may be sufficient, a single additional valve 30 several cylinders 3 to assign to the cylinders 3 to provide separate opening phases A can. In particular, it can be provided, the respective additional valve 30 so operate it for the assigned cylinder 3 generated differently large opening phases A, which follow each other directly.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102006028146 A1 [0005]
• DE 102006037934 A1 [0005]
• DE 102007004264 A1 [0005]
• DE 102008036494 A1 [0006]
• WO 2010/007026 A1 [0007]
• DE 102009020171 [0008]

Claims (14)

Method for operating an internal combustion engine ( 1 ), in particular a motor vehicle, - wherein the internal combustion engine ( 1 ) in an engine block ( 2 ) several with gas exchange valves ( 5 . 6 ) controlled cylinders ( 3 ) and one of the cylinders ( 3 ) Fresh air supply fresh air system ( 7 ), the at least one additional valve ( 30 ), which in at least two cylinders ( 3 ) leading fresh air channel ( 8th' . 8th'' ) upstream of the associated gas exchange valves ( 5 . 6 ) is arranged, - in which the respective additional valve ( 30 ) is operated so that opening phases (A), in which the additional valve ( 30 ) the fresh air duct ( 8th' . 8th'' ), and closing phases (B), in which the auxiliary valve ( 30 ) the fresh air duct ( 8th' . 8th'' ), alternate, - in which the respective additional valve ( 30 ) is operated so that for each associated cylinder ( 3 ) generates a separate opening phase (A), - in which the respective additional valve ( 30 ) is operated so that it can be used for the associated cylinders ( 3 ) generates differently large opening phases (A), which follow one another directly. A method according to claim 1, characterized in that the respective additional valve ( 30 ) a permanently rotating valve member ( 33 ), which in a complete revolution at least one of such a closing phase (B) forming closing angle range (β) and at least one such opening phase (A) forming opening angle range (α) passes, wherein for changing successive opening phases (A), the rotational speed of the valve member ( 33 ) is changed. Method according to claim 1 or 2, characterized in that - the respective additional valve ( 30 ) is actuated so that the opening phases (A) a predetermined phase position to the crankshaft angle of a crankshaft ( 35 ) of the internal combustion engine ( 1 ), - that the changing of the opening phases (A) takes place such that the predetermined phase angle to the crankshaft angle of the crankshaft ( 35 ) preserved. Method according to claim 3, characterized, - That in the event that such an opening phase (A) is increased, the preceding and / or the subsequent closing phase (B) is / is reduced, such that a period remains constant, and / or If, in the case that such an opening phase (A) is reduced, the preceding and / or subsequent closing phase (B) is / are increased, such that a period duration remains constant, - Wherein the respective period is formed by the time interval between the centers of two successive opening phases (A). Method according to one of claims 1 to 4, characterized in that the respective additional valve ( 30 ) is used for controlling an exhaust gas recirculation rate, wherein the exhaust gas recirculation rate is proportional to the size of the opening phase (A) behaves. Method according to one of claims 1 to 5, characterized in that the fresh air duct ( 8th' . 8th'' ) from the respective additional valve ( 30 ) to the associated cylinders ( 3 ) has different flow paths, which at the respective cylinder ( 3 ) at the same opening phases (A) would lead to differences in the fresh air filling and / or exhaust gas recirculation rate, wherein the different opening phases (A) are tuned to the different flow paths, that said differences are reduced, in particular eliminated. Method according to one of claims 1 to 6, characterized in that the respective additional valve ( 30 ) with the help of an electric motor ( 31 ) permanently rotating driven valve member ( 33 ), wherein the electric motor ( 31 ) for generating varying rotational speeds during one revolution of the valve member (US Pat. 33 ) is driven with a continuous drive function (f (x)). Method according to Claim 7, characterized in that the actuation function (f (x)) is the product of at least two continuous subfunctions (g (x), h (x)), wherein it can be provided in particular that the respective subfunction (g (x), h (x)) each contain a sine function, - that a first subfunction (g (x)) is a sine function of first power, - that a second subfunction (h (x)) is a sine function of third power, - the zero crossing of the first partial function (g (x)) with negative derivative to the middle of the opening phase (A) of the additional valve ( 30 ) is set, - that the maximum of the second partial function (h (x)) to the middle of the opening phase (A) of the additional valve ( 30 ) is set. Method according to one of claims 1 to 8, characterized in that - the fresh air system ( 7 ) downstream of the respective additional valve ( 30 ) to the gas exchange valves ( 5 . 6 ) and upstream of the respective additional valve ( 30 ) contains no controllable throttle, and / or - that the respective additional valve ( 30 ) for loading control of the associated cylinders ( 3 ) is operated. Method according to one of claims 1 to 9, characterized in that - in a four-stroke engine for every three cylinders ( 3 ) a single, these three cylinders ( 3 ) associated additional valve ( 30 ) is provided, - in particular in a four-stroke engine with exactly three cylinders ( 3 ) exactly such an additional valve ( 30 ) or in a four-stroke engine with exactly six cylinders ( 3 ) exactly two such additional valves ( 30 ) are provided, the three cylinders ( 3 ) assigned. Method according to one of claims 1 to 10, characterized in that - the opening phases (A) depending on a current operating state of the internal combustion engine ( 1 ) can be varied to adapt the opening phases (A) to the current operating state, - that the varying of the opening phases (A) to adapt to the current operating state of the internal combustion engine ( 1 ) such that a crankshaft angle in degrees ( 35 ) of the internal combustion engine ( 1 ) measured opening duration ( 41 ) of the opening phase (A) is varied, for which a closing time ( 40 ) of the opening phase (A) is varied with respect to its phase angle to the crankshaft angle, while an opening time (A) 39 ) of the opening phase (A) remains constant with respect to its phase angle to the crankshaft angle. A method according to claim 11, characterized in that the respective additional valve ( 30 ) a permanently rotating valve member ( 33 ) which, in one complete revolution, passes through at least one closing angle range (β) forming such a closing phase (B) and at least one opening angle range (α) forming such an opening phase (A), wherein for varying the closing time ( 41 ) the rotational speed of the valve member ( 33 ) is varied within a complete revolution, so that during the opening phases (A) other rotational speeds are present than during the closing phases (B). A method according to claim 12, characterized in that - to shorten the opening period ( 41 ) the rotational speed is increased during the opening phase (A) and reduced in the closing phase (B), such that the phase position of the opening time point (A) ( 39 ) remains constant to the crankshaft angle, and / or - that to increase the opening duration ( 41 ) the rotational speed is reduced during the opening phase (A) and increased in the closing phase (B), such that the phase position of the opening time point (A) ( 39 ) remains constant to the crankshaft angle. Method according to one of claims 11 to 13, characterized in that for the respective cylinder ( 3 ) the opening time ( 39 ) the opening phase of the respective additional valve ( 30 ) and through the gas exchange valves ( 5 . 6 ) coincide with a controlled start of intake or have a maximum distance of 10 ° crankshaft angle or at most a distance of 5 ° crankshaft angle.

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