DE102007027787A1 - Internal combustion engine with charge turbulence - Google Patents

Abstract

In an internal combustion engine having a piston (1) reciprocable in a longitudinal direction in a combustion chamber and at least one valve disposed in an end wall of the combustion chamber opposite the piston (1), at least one end face of the piston (1) the valve opposite to the valve (8b) is formed, the end face is oriented perpendicular to the longitudinal direction, and the pocket (8b) is asymmetrical with respect to a through a longitudinal axis of the valve (3, 4) extending and parallel to the longitudinal direction plane.

Description

The The present invention relates to an internal combustion engine with means for generating a twist in one in a combustion chamber of the engine introduced charge. With the help of the twist, the fuel distribution in the combustion chamber and should affect the combustion conditions be improved.

conventional Internal combustion engines often include swirling two inlet valves that are controlled differently the sucked via the intake valves in the combustion chamber Fresh gas to impose an angular momentum in the direction of the combustion chamber axis.

For example, an internal combustion engine with paired intake and exhaust valves is off DE 10 2005 002 389 A1 known. In this internal combustion engine, the valves are each offset by recesses in a roof-shaped end face of the piston. The complementary roof-shaped contours of the combustion chamber end wall and the piston end face have a strong damping effect on a swirl of the fresh gas charge, as long as the piston does not reach its top dead center and the fresh gas charge is compressed to a central recess of the piston.

task of the present invention is an alternative technique for production a twist in a fresh gas charge in a combustion chamber of an internal combustion engine specify.

The Task is solved by an internal combustion engine with one in a combustion chamber in a longitudinal direction and forth movable piston, at least one valve, in one the piston opposite end wall of the combustion chamber is arranged, wherein in an end face of the piston formed at least one valve opposite the bag is, the end face perpendicular to the longitudinal direction is oriented and the bag is asymmetrical in relation to a through a longitudinal axis of the valve extending and to the longitudinal direction the combustion chamber is parallel plane. By the orientation of the End face perpendicular to the longitudinal direction is a unnecessary damping when feeding gas induced swirl avoided. By the opposite of the valve Recess is made asymmetrical, gets between the valve head and seat in the combustion chamber gas flowing a preferred direction, by which a twist is induced.

The In particular, bag can be symmetrical with respect to the plane cylindrical wedge-shaped section which is in the top dead center position the piston receives a valve plate of the intake or exhaust valve, and one extending on a first side of the plane, the Symmetry breaking section include. As a result, gas from the valve, preferably in the direction of the symmetry breaking Section emanates.

Around is to keep the pressure drop when passing the valve low, is it is expedient that a plane floor surface of the cylindrical wedge-shaped section continuously in a bottom surface of the Symmetriebrechenden section passes.

The the bag opposite valve may be an inlet valve be for fresh gas; in this case a single one is enough Inlet valve to create a swirl in the fresh gas charge.

one according to the preferred embodiment, this is opposite the pocket Valve an exhaust valve, through which in the context of exhaust gas recirculation Exhaust gas can flow back into the combustion chamber. It It has been shown that with undirected inflow the recirculated exhaust gas stagnation points in the gas charge the combustion chamber, in particular near the bottom of the pockets, may occur, the previously impressed on the fresh gas swirl can destroy or at least strongly dampen. By the inventive arrangement also the swirled exhaust gas imparted a twist becomes, the emergence of such stagnation points reliable avoided, and the fresh gas impressed twist is not affected by the exhaust gas recirculation.

If the inlet valve is arranged to impart a twist to the fresh gas and the bag associated with the outlet valve one to a head of the Exhaust valve parallel bottom surface and an oblique Wall surface is preferably the slope of the oblique Wall surface in one with respect to the swirl flow of the fresh gas downstream portion of the pocket smaller as in an upstream area. So is the fresh gas, the into a gap between the bottom surface and the valve head has flowed in, relieving the escape from the gap, and swirl destroying congestion is avoided.

the same purpose, it serves when the slope of the oblique Wall surface in a longitudinal axis of the combustion chamber adjacent area is lower than in one of the wall of the combustion chamber adjacent area. So, unnecessarily strong direction changes avoided the circulating fresh gas.

In order to facilitate the escape of the recirculated exhaust gas from the pocket in the desired direction, the distance of an upper edge of the oblique wall surface from the longitudinal axis of the outlet valve is preferably in a with respect to the Swirl of the fresh gas downstream area of the bag larger than in an upstream area.

Cheap for the efficient imprinting of a twist also, if the bag altogether crescent-shaped in plan view is.

If a second parallel to the above-mentioned first valve Valve is provided, in other words, when two intake or two exhaust valves are present, is expediently also the second valve opposite a second pocket of the piston. This is preferably also asymmetric for swirl generation with respect to one through a longitudinal axis of the second Valve extending and parallel to the longitudinal direction Level.

The first and the second bag can be through an unfolded Bridge the face to be separated from each other the gas flows passing through the two valves as possible unaffected by the other to be able to impose a spin. It is also conceivable that the first and the second bag on The face of the cylinder merge into each other.

If in an internal combustion engine with one in a combustion chamber in one Longitudinal reciprocating piston two parallel Valves in a front wall opposite the piston the combustion chamber arranged mirror-inverted with respect to a mirror plane are and in an end face of the piston one the valves Opposite bag is formed, it can be used to generate a twist also suffice that the bag is asymmetrical in terms of is on the mirror plane.

The Asymmetry of the bag can be expressed in particular in that on a first side of the through the longitudinal axis the valve extending plane lying part of the bag a smaller Base area and / or a smaller volume than the part lying on the other side of this plane.

Further Features and advantages of the invention will become apparent from the following Description of embodiments with reference on the attached figures. Show it:

1 a schematic section through a combustion chamber of an internal combustion engine according to the invention;

2 a plan view of a piston of the internal combustion engine according to a first embodiment of the invention;

3A to 3C Cuts through a pocket of the piston 2 ;

4 a plan view of a piston according to a second embodiment; and

5 a plan view of a piston according to a third embodiment.

1 is a schematic section through a combustion chamber of an internal combustion engine according to the invention with a piston which can be moved back and forth in the direction of the longitudinal axis of the combustion chamber 1 and a cylinder head forming the upper end of the combustion chamber 2 , In the cylinder head 2 in each case two of the combustion chamber associated with intake valves 3 or exhaust valves 4 arranged. The cutting plane of the 1 extends along the shafts 5 one each of the inlet and outlet valves 3 . 4 ; behind each mirrored in relation to the plane of the 1 parallel mirror plane arranged second valves are not visible.

plates 6 the valves 3 . 4 Opposite are bags 7 . 8th in the top of the piston 1 shaped. In the pocket 8th can the plate 6 the exhaust valve 4 engage, leaving the exhaust valve 4 remain open at the top dead center of the piston movement and can allow a complete expulsion of the exhaust gas from the combustion chamber. By being kept open for a short time beyond top dead center, a controlled amount of exhaust gas can flow back into the combustion chamber in the subsequent suction phase. Accordingly, the plate can 6 of the inlet valve 3 at the top dead center in the bag 7 engage to allow from the beginning of the suction phase to the flow of fresh air or fresh air / fuel mixture into the combustion chamber.

The use of two inlet valves 3 per combustion chamber allows the generation of a twist in the incoming fresh gas by the two inlet valves 3 be opened differently. When exhaust gas recirculation takes place, the plates projecting into the combustion chamber are impaired 6 the exhaust valves 4 this swirl, and back-flowing exhaust accumulates in particular in the bag 8th where a fresh gas flow circulating along the piston surface and the recirculated exhaust gas meet. If this jam is so strong that it deflects the fresh gas flow circulating in the combustion chamber towards the center of the combustion chamber, its swirl is greatly attenuated. In order to avoid this, according to the embodiment shown here, the pockets are provided 8th of the piston 1 asymmetric in a way that also gives back-flowing exhaust gas an angular momentum that is the same as that of the injected fresh gas.

A first embodiment of such a piston 1 is in 2 shown in a plan view. The two intake valves 3 associated pockets 7 Here each have the shape of a cylinder wedge, with one of the valve plates 6 opposite flat inclined surface 10 and a cylindrically curved side surface 11 , While this shape at one of the exhaust valves 4 opposite pockets 8a is maintained, is the second bag 8b crescent-shaped counterclockwise, so that when the plate 6 the associated exhaust valve in the bag 8B engages the side surface 11b the outflow of exhaust gas only on the adjacent pocket 8a facing side, left of the in 2 With 13 designated cutting plane of the 1 , while preventing the exhaust gas on the opposite side, to the right of the plane 13 , free in the extension 12b can flow out. Thus, the backflowing exhaust gas receives an angular momentum in the counterclockwise direction, which supports the swirl of the fresh gas fed in and improves the turbulence of the recirculated exhaust gas with the fresh gas.

3A to 3C illustrate a way, like the bag 8b can be constructed. 3A shows a section through the bag 8b along the line 13a from 2 . 3B a cut along the plane 13 and 3C a section along the line 13c , In these three figures is a longitudinal axis of the (not shown in the figures) valve stem 5 the exhaust valve 4 each with 14 and a generatrix of one to the longitudinal axis 14 coaxial imaginary cylinder, within which is the head 6 the exhaust valve moves, with 15 designated. Inside the imaginary cylinder 15 lies the flat inclined surface 10 , At one outside of the cylinder 15 lying rounding 16 go the slanted surface 10 continuously in the side surface 11b over, on average, the 3A parallel to the longitudinal axis 14 at a steep angle with respect to the piston top.

On average, the 3B is the side surface 11 still steep but no longer parallel to the longitudinal axis 14 , By the angle α between the longitudinal axis 14 and the side surface 11 counterclockwise with respect to the top view of 2 continuously increases, becomes a spiral course of an edge 17 , on which the side surface 11 and the end face of the cylinder head 2 cut, with respect to the valve axis 14 receive.

On average, the 3C is the angle α between the longitudinal axis 14 and the inclined surface 11 again greatly increased, and the depth of the bag is less than the average of the 3B , This tendency is not shown here, in the counterclockwise direction to the cutting plane 13c continuing cutting planes.

This design of the bag 8b allows it both below the valve disk 6 in the pocket 8b fresh gas flowed in as well as top exhaust gas, the bag 8b Leave blockage again, so that the fresh gas impressed swirl is not affected.

In the cuts 3A , B and C is the distance of rounding 16 from the longitudinal axis 14 the inlet valve always the same, ie the rounding 16 extends on a circular arc, along which arc the angle between the inclined surface 10 and the side surface 11b getting duller. According to a second cross-sectional design, also the escape of gas from the bag 8b facilitated without congestion, is the angle between the inclined surface 10 and the side surface 11b in each section along the longitudinal axis 14 equal, and the radius of the side surface 11b increases in the direction of circulation of the gas mixture to spiral. The resulting course of the edge 17 can be the same as in the case of 3A to C. "Compromise solutions" between this second cross-sectional design and that of the 3A to C are also considered.

In the embodiment of 2 may be the problem that the bottom of the plate 6 of the bag 8a associated exhaust valve is circulated by circulating fresh gas, so this in the bag 8a led in and on its side surface 11 is deflected towards the cylinder center. Due to the conservation of the angular momentum, the gas deflected inwards must be accelerated, and the energy required for this purpose is withdrawn from the circulation of the rest of the gas, that is, it congests. Two embodiments, which avoid this, are based on the 4 and 5 described.

The in 4 shown second embodiment, the cylinder head carries 2 two pockets associated with the exhaust valves, each asymmetrically extended to the same side 8a ' . 8b ' , The shape of the bag 8b ' is like the bag 8b out 2 ; the pocket 8a ' is by a tapered section 12a ' extended in one of the circumference of the piston 1 and the bag 8b limited gusset intervenes. In this embodiment contributes to both exhaust valves 4 backflowing exhaust gas to the swirl in the combustion chamber at.

The pocket 8a ' can be constructed in a similar manner as above based on the 3A . 3B . 3C for the bag 8b explains; the divergent edge profiles of the sections 12a ' on the one hand and 12b respectively. 12b ' On the other hand, depending on the selected in each case course of the slope of the side surface arise 11a respectively. 11b , By at a downstream side of the bag with respect to the circulation direction of the fresh gas (counterclockwise) 8a ' one on the middle of the piston top tapered section of the oblique side surface 11a flattened, can in the bag 8a ' , between valve head and bottom surface 10 Ingress fresh gas easily and jammed again out of the bag 8a ' escape.

At the in 5 the embodiment shown are the pockets of both exhaust valves 4 to a single bag 8th'' with a common, to the valve stems 5 vertical inclined surface 10 '' merged. During the backflow of exhaust gas through the left exhaust valve 4 still on the left side of the bag 8th'' through a steep side surface 11 '' is restricted, is the backflow of exhaust gas on the right exhaust valve 4 nowhere by a steep side surface of the piston 1 with special needs. Nevertheless, a torque is also applied to this exhaust gas, since at the moment of exhaust gas reflux both exhaust valves 4 are open and exhaust of the right exhaust valve 4 from left through the outlet valve 4 back-flowed exhaust gas is flushed in the counterclockwise direction.

Again, the top edge has 17 the side surface 11 at least locally, near one of the exhaust valves 4 , a counter-clockwise diverging with respect to the axis of the valve in question, to an outflow of both the circulating fresh gas and the recirculated exhaust gas from the valve disk 6 to favor in a counterclockwise direction.

1

piston

2

cylinder head

3

intake valve

4

outlet valve

5

shaft

6

Plate

7, 8th

bag

9

Area

10

sloping surface

11

side surface

12

extension

13

level

14

valve axis

15

cylinder

16

curve

17

edge

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• DE 102005002389 A1 [0003]

Claims (15)

Internal combustion engine with a piston which can be moved back and forth in a combustion chamber in a longitudinal direction ( 1 ), at least one valve ( 3 . 4 ), which is in a piston ( 1 ) opposite end wall ( 2 ) of the combustion chamber is arranged, wherein in an end face of the piston ( 1 ) at least one valve opposite the valve ( 7 . 8th ; 8a . 8b ; 8a ' . 8b ' . 8th'' ) is formed, characterized in that the end face is oriented perpendicular to the longitudinal direction and the pocket ( 7 . 8th ; 8a . 8b ; 8a ' . 8b ' . 8th'' ) asymmetrically with respect to a through a longitudinal axis of the valve ( 3 . 4 ) and parallel to the longitudinal direction plane ( 13 ). Internal combustion engine according to claim 1, characterized in that the bag ( 8b ; 8a ' . 8b ' ) a symmetrical cylindrical wedge-shaped section with respect to the plane and a predominantly on a first side of the plane ( 13 ) extending symmetry breaking section ( 12b ; 12a ' . 12b ' ). Internal combustion engine according to claim 2, characterized in that a flat bottom surface ( 10 ) of the cylindrical wedge-shaped portion continuously in a bottom surface of the symmetry-breaking portion ( 12b ; 12a ' . 12b ' ) passes over. Internal combustion engine according to one of the preceding claims, characterized in that that of the bag ( 7 ) opposed valve an inlet valve ( 3 ). Internal combustion engine according to one of claims 1 to 3, characterized in that the bag ( 8th ; 8a . 8b ; 8a ' . 8b ' . 8th'' ) opposite valve an outlet valve ( 4 ). Internal combustion engine according to claim 5, characterized in that an inlet valve ( 3 ) is adapted to impart a spin to the fresh gas fed into the combustion chamber, that the pocket ( 8b ) one to one head ( 6 ) of the exhaust valve ( 4 ) parallel floor surface ( 10 ) and an inclined wall surface ( 11 ), and that the slope of the sloping wall surface ( 11 ) in a region downstream of the swirling flow of the fresh gas ( 3C ) the pocket ( 8b ) is smaller than in an upstream region ( 3A ). Internal combustion engine according to claim 5, characterized in that an inlet valve ( 3 ) is adapted to impart a spin to the fresh gas fed into the combustion chamber, that the pocket ( 8a ' ) one to one head ( 6 ) of the valve parallel floor surface ( 10 ) and an inclined wall surface ( 11 ), and that the slope of the sloping wall surface ( 11 ) is lower in an area adjacent to a longitudinal axis of the combustion chamber than in an area adjacent to the wall of the combustion chamber. Internal combustion engine according to claim 5, characterized in that the one inlet valve ( 3 ) is adapted to impart a spin to the fresh gas fed into the combustion chamber, that the pocket ( 8a ' ) one to one head ( 6 ) of the valve parallel floor surface ( 10 ) and an inclined wall surface ( 11 ), and that the distance of an upper edge of the inclined wall surface ( 11 ) from the longitudinal axis of the exhaust valve ( 4 ) is greater in an area of the pocket downstream of the swirl of the fresh gas than in an upstream area. Internal combustion engine according to one of the preceding claims, characterized in that the bag ( 8b ; 8a ' . 8b ' . 8th'' ) is crescent-shaped in plan view. Internal combustion engine according to one of the preceding claims, characterized in that a to the first valve ( 3 ; 4 ) parallel second valve ( 3 ; 4 ) and that the second valve ( 3 ; 4 ) a second bag ( 7 ; 8th ) of the piston ( 1 ) is opposite. Internal combustion engine according to claim 7, characterized in that the second pocket ( 8a ' ) with respect to a through a longitudinal axis of the second valve ( 4 ) and parallel to the longitudinal direction ( 13 ) is asymmetric. Internal combustion engine according to claim 7 or 8, characterized in that the first and the second pocket ( 8a . 8b ; 8a ' . 8b ' ) are separated by an unrecipitated web of the face. Internal combustion engine according to claim 7 or 8, characterized in that the first and the second pocket ( 8th'' ) merge. Internal combustion engine with a piston reciprocating in a longitudinal direction in a combustion chamber ( 1 ) and two parallel valves ( 4 ), which are in a piston ( 1 ) opposite end wall ( 2 ) of the combustion chamber are arranged in mirror image with respect to a plane, wherein in an end face of the piston ( 1 ) one of the valves ( 4 ) opposite bag ( 8th'' ), characterized in that the pocket ( 8th'' ) is asymmetrical with respect to the plane. Internal combustion engine according to one of the preceding claims, characterized in that the part of the pocket (1) lying on a first side of the plane ( 8b ; 8a ' . 8b '; 8th'' ) has a smaller footprint and / or a smaller volume than that on the other side of the plane lying part.