DE102015014753A1 - Cylinder head for an internal combustion engine, in particular a motor vehicle - Google Patents

Abstract

The invention relates to a cylinder head for an internal combustion engine, in particular a motor vehicle, having at least one inlet channel (14) for introducing a gas charge into a combustion chamber (10) of the internal combustion engine, with at least one inlet valve (16) associated with the inlet channel (14) having at least one the inlet channel (14) at least partially defining and a valve seat (22) for the inlet valve (16) forming the wall (20), and at least one relative to the wall (20) movable inlet valve mask (32) which in at least one position the valve seat ( 22) projects beyond the combustion chamber (10), wherein the inlet valve masking (32) about an axis of rotation relative to the wall (20) is rotatable.

Description

The invention relates to a cylinder head for an internal combustion engine, in particular a motor vehicle, according to the preamble of claim 1.

Such a cylinder head for an internal combustion engine, in particular a motor vehicle such as a passenger car, is already the DE 10 2005 050 777 A1 to be known as known. The cylinder head has at least one inlet channel for introducing a gas charge into a combustion chamber of the internal combustion engine. Furthermore, the cylinder head has at least one inlet valve assigned to the inlet valve, by means of which at least one inlet opening, via which the gas charge can flow from the inlet channel into the combustion chamber, is adjustable. This means that the inlet valve is used for controlling, that is adjusting the inlet opening. Usually, the inlet valve is movable between a closed position fluidically blocking the inlet opening and thus the inlet channel and at least one open position releasing the inlet channel, wherein the gas charge in the open position can flow from the inlet channel into the combustion chamber. During the movement from the closed position to the open position, the inlet valve executes a stroke, which is also referred to as valve lift.

Adjustable valve trains are known from the general state of the art, in which the lift of the inlet valve is adjustable and can thus be switched between at least two values.

The cylinder head further has at least one wall which at least partially delimits the inlet channel or the inlet opening, through which wall a valve seat for the inlet valve is formed. The inlet valve sits in its closed position on the valve seat, whereby the inlet channel is fluidly blocked by means of the inlet valve.

Furthermore, the cylinder head has at least one inlet valve masking which can be moved relative to the wall and projects beyond the valve seat toward the combustion chamber in at least one position. This means that the inlet valve masking is movable between at least two different positions, wherein the inlet valve masking projects beyond the valve seat to the combustion chamber in at least one of the positions.

From the general state of the art are also fixed, that is immovable intake valve masks known that extend beyond the valve seat to the combustion chamber. The inlet valve masking serves to influence a movement of the gas charge flowing through the inlet channel and flowing from the inlet channel into the combustion chamber. In particular, the inlet valve masking serves to impart a desired movement or type of movement to the gas charge. The movement of the gas charge is also called charge movement. The gas charge is usually air or a fuel-air mixture, which is also referred to for simplicity as a mixture. The fuel-air mixture can be burned with the formation of exhaust gas. The charge movement and the mixture preparation of the fuel-air mixture are essential variables in the optimization of combustion processes of internal combustion engines.

Intake valve masking, also referred to as valve masking or valve seat masking, is known as an effective technology for increasing charge motion. Here, the incoming gas charge or the incoming air is selectively influenced as a result of an at least partial cover between the inlet valve and the combustion chamber. The air flows into the combustion chamber of the internal combustion engine as a result of a reduction of an opening cross-section of the inlet channel caused by the inlet valve marking with increased speed and with an altered entry angle. It comes with small valve strokes to the overflow of the inlet valve, which causes an increase in the charge movement, in particular in the form of a tumble-shaped charge movement. The tumble-shaped charge motion is also referred to as tumble. This has a positive effect on the mixture preparation, that is, on the mixing of the fuel with the air.

As a result, a high degree of homogenization due to a higher turbulent kinetic energy at the time of ignition is available, which has a positive effect with respect to ignition and burn-through behavior or burning time. The valve masking still acts even when the inlet valve has left the area of the valve masking, that is to say when, for example, a valve disk of the inlet valve is not arranged in coincidence with the valve masking. However, the effect of the valve masking diminishes as the axial distance between the inlet valve and the valve mask increases.

• – eine starre, das heißt unbewegliche Ventilmaskierung ist nur für genau einen Ventilhub optimal ausgelegt
• – geringer effektiver Öffnungsquerschnitt, woraus Nachteile für den Volllastbetrieb resultieren

The advantages of intake valve masking are counteracted by the following disadvantages:

• - A rigid, that is immovable Ventilmaskierung is optimally designed for just one valve lift
• - Low effective opening area, resulting in disadvantages for full load operation

Object of the present invention is therefore to develop a cylinder head of the type mentioned in such a way that a particularly advantageous operation of the internal combustion engine can be realized.

This object is achieved by a cylinder head having the features of patent claim 1. Advantageous embodiments with expedient developments of the invention are specified in the remaining claims.

In order to develop a cylinder head specified in the preamble of claim 1 species such that a particularly advantageous and efficient operation of the internal combustion engine can be realized, it is inventively provided that the intake valve masking is rotatable about an axis of rotation relative to the wall. In this way, a particularly high efficiency of the internal combustion engine can be realized while realizing only low raw emissions of the internal combustion engine. By means of the inlet valve masking, it is possible to realize an optimized combustion of a fuel-air mixture in the combustion chamber as a result of adapted, best possible mixture preparation. As a result, the fuel consumption and the raw emissions can be kept particularly low, at least almost in the entire map range of the internal combustion engine.

The inlet valve masking is a variable inlet valve masking, since it is rotatable relative to the wall and optionally additionally translationally movable, that is displaceable. By means of this variable intake valve masking, the charge movement can be specifically influenced and controlled. As a result, at least almost the best possible mixture formation can be achieved, which is adjustable for at least almost any operating point of the internal combustion engine and ensures at least almost optimal combustion.

Preferably, the internal combustion engine is designed as a reciprocating internal combustion engine, wherein the combustion chamber is a cylinder. In particular, the internal combustion engine is designed as a gasoline engine with direct injection, wherein the internal combustion engine preferably for driving a motor vehicle, in particular passenger car, is used.

The invention also includes a method for operating an internal combustion engine, which has a cylinder head according to the invention. In the method, the intake valve masking is rotated about the axis of rotation and possibly additionally moved in translation. By means of the method according to the invention, the disadvantages of intake valve masking mentioned at the outset can be avoided since the intake valve masking is fully or partially variable.

Further advantages, features and details of the invention will become apparent from the following description of a preferred embodiment and from the drawing. The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or in the figures alone can be used not only in the respectively specified combination but also in other combinations or in isolation, without the scope of To leave invention.

The drawing shows in:

1 a schematic bottom view of a cylinder head for an internal combustion engine, in particular a motor vehicle, with a variable inlet valve masking, which is rotatory and optionally translationally movable;

2 partially a schematic sectional view of the cylinder head;

3 a diagram illustrating a method for operating the internal combustion engine; and

4 another diagram illustrating the method for operating the internal combustion engine.

In the figures, identical or functionally identical elements are provided with the same reference numerals.

1 shows a schematic bottom view of a cylinder head for an internal combustion engine, which is designed for example as a reciprocating internal combustion engine and at least one combustion chamber, in particular in the form of a cylinder which in 2 partially recognizable and there with 10 is designated. The internal combustion engine is a component of a motor vehicle and serves to drive this.

Out 1 can be seen that through the cylinder head a combustion chamber roof 12 is formed, wherein in finished manufactured state of the internal combustion engine, the cylinder 10 through the combustion chamber roof 12 partially limited. In the finished state of the internal combustion engine, the cylinder head is connected to a cylinder housing through which the cylinder 10 is formed.

The cylinder head has two intake ports for introducing a respective gas charge into the cylinder 10 on. Of these intake ports is in 2 one with 14 designated inlet channel recognizable, the previous and following comments on the inlet channel 14 are also transferable to the other inlet channel.

The inlet channels are each a gas exchange valve in the form of an inlet valve 16 associated with the cylinder head, wherein the respective inlet valve 16 is translationally movable between a closed position and at least one open position. In the closed position, the respective inlet channel 14 , in particular an inlet opening 18 ( 2 ) of the intake passage 14 , by means of the inlet valve 16 fluidly obstructed, so no over the inlet channel 14 in the cylinder 10 can flow. In the open position gives the inlet valve 16 the inlet channel 14 or the inlet opening 18 free, allowing the gas charge from the inlet duct 14 in the cylinder 10 can flow in.

During the movement of the inlet valve 16 from the closed position into the open position leads the inlet valve 16 a stroke, which is also referred to as valve lift. In this case, for example, a variable valve train is provided, by means of which the valve lift is adjustable, that is variably variable.

The cylinder head also has an inlet channel 14 at least partially delimiting wall 20 on, through which a valve seat 22 of the inlet valve 16 is formed. In the closed position sits the inlet valve 16 on the valve seat 22 , whereby the inlet channel 14 by means of the inlet valve 16 is fluidly locked. By this is meant that the inlet valve 16 in the closed position on the valve seat 22 is applied. The inlet valve 16 has a valve plate 24 and one with the valve plate 24 connected valve stem 27 on, with the valve disk 24 on the valve seat 22 sitting in the closed position. Here is the inlet valve 16 relative to the wall 20 translationally movable in a direction of movement.

The cylinder head also has two cylinders 10 associated and not visible in the figures outlet channels, which in each case a gas exchange valve in the form of an exhaust valve 26 assigned. The respective outlet valve 26 is also translationally movable between a closed position and at least one open position. In the closed position, the respective outlet channel through the associated outlet valve 26 fluidly blocked. In the open position, the outlet valve releases the associated outlet channel.

The over the respective inlet channel 14 in the cylinder 10 incoming gas charge comprises at least air which thus enters the cylinder 10 flows. The cylinder 10 Furthermore, a fuel, in particular liquid fuel, is supplied, so that in the cylinder 10 a fuel-air mixture is present. This fuel-air mixture is ignited, whereupon the fuel-air mixture burns to form exhaust gas. This exhaust gas can be opened with exhaust valves 26 via the outlet channels from the cylinder 10 be dissipated.

In the present case, the internal combustion engine has a direct injection, which is also referred to as direct fuel injection. The internal combustion engine is designed for example as a gasoline engine. In the context of direct injection is the cylinder 10 a in 1 recognizable injector 28 assigned, which is also referred to as injection element. By means of the injector 28 can the fuel directly into the cylinder 10 be injected.

The internal combustion engine also has spark ignition. Here is the cylinder 10 an ignition element in the form of a spark plug 30 assigned, by means of which a spark can be generated. This spark causes the fuel-air mixture in the cylinder 10 ignited. A point in time at which the fuel-air mixture is ignited by means of the spark is also referred to as ignition time. A time at which the fuel by means of the injector 28 in the cylinder 10 is injected, is also referred to as injection timing.

It is also conceivable that the internal combustion engine is designed as a self-igniting internal combustion engine.

The cylinder head also has each inlet channel and thus per inlet valve 16 one relative to the wall 20 movable intake valve masking 32 on which - as in 1 by double arrows 34 is illustrated - around a respective axis of rotation relative to the wall 20 is rotatable. This means that the respective intake valve masking 32 , which is also referred to as valve masking, valve seat masking or inlet valve seat masking, is rotatable about at least two different positions about the axis of rotation, wherein the valve mask in at least one of the positions the valve seat 22 to the cylinder 10 towers over.

In the embodiment according to 1 the inlet valve masking extends 32 in the circumferential direction of the valve seat 22 about 180 degrees around the valve seat 22 , wherein any suitable extent of the intake valve masking 32 in the circumferential direction of the valve seat 22 is conceivable.

Out 2 it can be seen that the respective inlet valve masking 32 also relative to the wall 20 is displaceable, what is in 2 by a double arrow 36 is illustrated. The intake valve masking 32 is for example along a longitudinal axis relative to the wall 20 displaceable in at least two different positions and projects beyond the valve seat 22 to the cylinder 10 in at least one of these positions.

Out 1 and 2 it can be seen that the respective inlet valve masking 32 is formed by a masking element, which is an additional, separate from the wall 20 made and, for example, on the wall 20 stored component is, for example, designed as a sleeve and integrated into the cylinder head.

Because the intake valve masking 32 is variable in particular along its longitudinal axis and is rotatable about the axis of rotation, the intake valve masking 32 designed as a variable, in particular fully variable valve masking. As a result, for example, for each operating point of the internal combustion engine, an at least almost optimal position or position of the valve masking can be set. By turning and / or moving the inlet valve masking 32 For example, a measure about which the intake valve masking 32 the valve seat 22 to the cylinder 10 towers over, be set. This measure is also referred to as height or masking height. In particular, the masking height is adjusted by moving the valve masking. The height of the turbulence energy is set, in particular regulated, by the masking height.

Furthermore, it is preferably provided that an orientation of the respective intake valve masking 32 is adjusted by turning it around the axis of rotation.

3 and 4 show respective diagrams, with reference to which a method for operating the internal combustion engine will be described below. As part of the process, the respective intake valve masking 32 rotated about the axis of rotation and optionally moved.

On the respective abscissa 38 of the diagram, the speed of the internal combustion engine is plotted, with the corresponding ordinate 40 the load of the internal combustion engine is plotted on the respective diagram. 3 and 4 thus show the map or operating map of the internal combustion engine, wherein in 3 and 4 with 42 designated full load line is recognizable. 3 illustrates the setting or adjustment of the masking height in the operating map schematically. A directional arrow 44 indicates an increasing masking height, with a directional arrow 46 illustrates a decreasing masking height. Out 3 is thus apparent that towards high loads or engine loads, it is advantageous to reduce the masking height continuously, so that in the region of full load, the masking height is minimized or even completely reduced. By this complete reduction of the masking height, it is to be understood that the masking height is zero, so that the inlet valve masking 32 the valve seat 22 not to the cylinder 10 towers over. Thus, for a particularly high engine power, a maximum intake valve opening cross-section is set, via which the gas charge into the cylinder 10 can flow in.

4 illustrates the orientation of the respective intake valve masking 32 that is their respective position around the axis of rotation. The position of the valve masking, that is to say the orientation of the valve masking about its axis of rotation, influences in particular the shape of the charge movement that forms. Due to the variable adjustment of the valve masking, it is possible to realize different charge motion concepts in certain areas of the characteristic map of the internal combustion engine. By way of example, in the low-load range, by twisting one of the valve masks, in particular in the case of a 4-valve cylinder head design, a swirl component can be added to the existing tumble flow. This is in 4 illustrated by a first state designated Z1.

In 4 is also shown a second state Z2, in which the respective valve masks have the same orientation. In state Z1, the relative to the image plane of 1 left intake valve masking 32 twisted relative to the second state Z2, while related to the image plane of 2 right inlet valve masking 32 in the states Z1 and Z2 has the same orientation. This means that in a transition from the second state Z2 to the first state Z1, a relative rotation between the valve masks (intake valve masks 32 ) he follows. A high charge movement is desirable especially in homogeneous lean combustion. It ensures high lean rates with good air stability and low emissions of the internal combustion engine.

Thus, an at least nearly optimal turbulent kinetic energy in the area of the spark plug 30 provided. Excessively high turbulence values at the spark plug 30 , which can lead to flame drift and flame extinction, can be avoided by reducing the masking height. The combination of Masking height and orientation of the valve mask allows an at least almost optimal setting individually for each operating point of the internal combustion engine. This can be used positively in particular in an internal combustion engine, which is usually operated in a vehicle in a large map range, since in this case, depending on the combustion method and the load point, different requirements with respect to charge movement occur. These can be completely contrary to each other as described. Because the intake valve masking 32 is rotatable and displaceable, is the intake valve masking 32 fully variable. With such a fully variable valve masking, one is able to meet the above requirements. When using such a valve masking, it is preferable to consider a corresponding seal in the combustion chamber at prevailing high pressures and temperatures as well as against the background of a close position to a water jacket.

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 102005050777 A1 [0002]

Claims (6)

Cylinder head for an internal combustion engine, in particular a motor vehicle, with at least one inlet channel ( 14 ) for introducing a gas charge into a combustion chamber ( 10 ) of the internal combustion engine, with at least one of the inlet channel ( 14 ) associated intake valve ( 16 ), with at least one inlet channel ( 14 ) at least partially delimiting and a valve seat ( 22 ) for the inlet valve ( 16 ) forming wall ( 20 ), and with at least one relative to the wall ( 20 ) movable intake valve masking ( 32 ), which in at least one position the valve seat ( 22 ) to the combustion chamber ( 10 ), characterized in that the inlet valve masking ( 32 ) about an axis of rotation relative to the wall ( 20 ) is rotatable. Cylinder head according to claim 1, characterized in that by turning the inlet valve masking ( 32 ) about the axis of rotation a measure around which the intake valve masking ( 32 ) the valve seat ( 22 ) to the combustion chamber ( 10 ) towers over, is adjustable. Cylinder head according to claim 1 or 2, characterized in that the cylinder head has two intake passages ( 14 ) for introducing a respective gas charge into the combustion chamber ( 10 ) having. Cylinder head according to claim 3, characterized in that the respective intake valve masking ( 32 ) of the inlet channels ( 14 ) are rotated against each other. Cylinder head according to claim 3, characterized in that the respective intake valve masking ( 32 ) of the inlet channels ( 14 ) have the same orientation. Method for operating an internal combustion engine with a cylinder head according to one of the preceding claims, in which the intake valve masking ( 32 ) is rotated about the axis of rotation.

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