DE102015202361A1 - Reciprocating internal combustion engine - Google Patents

Abstract

The reciprocating internal combustion engine (10) is provided with at least one cylinder (16) having a peripheral wall (18) and a cylinder cover wall (20) and a piston (22) movable up and down in the cylinder (16) with a piston head (24), wherein the peripheral wall (18) of the cylinder (16) and the cylinder cover wall (20) and the piston head (24) form a combustion chamber (26). Further, the reciprocating internal combustion engine (10) comprises means (36) for introducing a gaseous medium into the combustion chamber (26), means (38) for discharging a gaseous medium from the combustion chamber (26), means (40) along an injection jet axis ( 42) taking place injecting fuel into the combustion chamber (26) and means (54) for igniting the fuel-gas mixture in the combustion chamber (26). A trough (62) with a trough surface (63) is formed in the piston head (24) to assist in the formation and maintenance of a tumble flow (72) of the fuel gas mixture within the combustion chamber (26). The shape of the well surface (63) is formed as part of an outer surface of an elongated, substantially rotationally symmetric body having a longitudinal axis which forms the axis of rotation (64) of the body and transverse to the upward and downward movement (70) of the piston (22 ) is aligned. The rotational or longitudinal axis (64) of the rotationally symmetrical body extends transversely to the fuel injection beam axis (42).

Description

The invention relates to a reciprocating internal combustion engine and in particular a reciprocating internal combustion engine, in the combustion chamber during the introduction of fuel and gas (in particular air) and during the compression of the fuel-gas mixture, a tumble flow is created and maintained.

It is known to provide the piston crown in the combustion chamber of a cylinder of a reciprocating internal combustion engine with a specially formed trough, which mixes the incoming gas as homogeneously as possible with the injected fuel, with the formation of an effective possible for mixing and combustion turbulent flow. The wells of piston bottoms known in the prior art are generally asymmetrical in design and have asymmetrically arranged impact or deflecting surfaces along which the inflowing gas flows along with the introduced fuel under a sudden change in the flow direction.

Examples of different trough shapes in the bottoms of pistons of reciprocating internal combustion engines are in DE 103 54 682 A1 . EP 0 937 890 A2 . EP 0 997 622 A1 . WO 01/49996 A1 and US 2003/0056748 A1 described.

Out DE 10 2012 103 195 A1 is a piston for a reciprocating internal combustion engine with a cup-shaped, symmetrical with respect to a vertical axis or known with an elliptical shape.

The object of the invention is to improve the trough shape of piston for reciprocating internal combustion engines with a view to improving the homogenization of the fuel-gas mixture in the combustion chamber during the introduction of the fuel and the gas and the compression of this fuel-gas mixture in the combustion chamber.

• – mindestens einem Zylinder, der eine Umfangswand und eine Zylinderdeckwand aufweist,
• – einem in dem Zylinder auf- und abbewegbaren Kolben mit einem Kolbenboden,
• – wobei die Umfangswand des Zylinders sowie dessen Zylinderdeckwand und der Kolbenboden einen Brennraum bilden,
• – Mittel zum Einlassen eines gasförmigen Mediums in den Brennraum,
• – Mittel zum Auslassen eines gasförmigen Mediums aus dem Brennraum,
• – Mittel zum längs einer Einspritzstrahlachse erfolgenden Einspritzen von Kraftstoff in den Brennraum und
• – Mittel zum Zünden des Kraftstoff-Gas-Gemisches im Brennraum,
• – wobei in dem Kolbenboden zur Unterstützung des Entstehens und des Aufrechterhaltens einer Tumble-Strömung des Kraftstoff-Gas-Gemisches innerhalb des Brennraums eine Mulde mit einer Muldenoberfläche ausgebildet ist.

To solve this problem, a reciprocating internal combustion engine is proposed with the invention, which is provided with

• At least one cylinder having a peripheral wall and a cylinder cover wall,
• A piston which can be moved up and down in the cylinder and has a piston head,
• - Wherein the peripheral wall of the cylinder and the cylinder cover wall and the piston crown form a combustion chamber,
• Means for introducing a gaseous medium into the combustion chamber,
• Means for discharging a gaseous medium from the combustion chamber,
• - Means for taking place along an injection axis of injection of fuel into the combustion chamber and
• Means for igniting the fuel gas mixture in the combustion chamber,
• - Wherein formed in the piston head to support the emergence and maintenance of a tumble flow of the fuel-gas mixture within the combustion chamber, a trough with a trough surface.

• – dass die Form der Muldenoberfläche als Teil der Außenfläche eines länglichen, im Wesentlichen rotationssymmetrischen Körpers ausgebildet ist, der eine Längsachse aufweist, die die Rotationsachse des Körpers bildet und die quer zur Auf- und Abbewegung des Kolbens ausgerichtet ist, und
• – dass die Rotations- bzw. Längsachse des rotationssymmetrischen Körpers quer zur Kraftstoff-Einspritzstrahlachse verläuft.

In this reciprocating internal combustion engine, the invention provides

• - That the shape of the well surface is formed as part of the outer surface of an elongated, substantially rotationally symmetrical body having a longitudinal axis which forms the axis of rotation of the body and which is aligned transversely to the up and down movement of the piston, and
• - That the rotational or longitudinal axis of the rotationally symmetrical body is transverse to the fuel injection jet axis.

The reciprocating internal combustion engine according to the invention is provided with at least one cylinder, which is usually in an engine block with cylinder head. In the or in each cylinder is movable up and down a piston arranged with a piston crown. The peripheral wall of the cylinder and the cylinder top wall (as part of the cylinder head) and the piston crown form the combustion chamber of the cylinder.

Furthermore, the reciprocating internal combustion engine according to the invention comprises means for introducing a gaseous medium, in particular air, into the combustion chamber and means for discharging a gaseous medium, namely the combustion gases, from the combustion chamber. These means are usually intake and exhaust valves, of which at least one is provided per cylinder. Fuel is injected into the combustion chamber via another means, along an injection jet axis. This is usually done via an injection channel, which opens into the combustion chamber. Finally, the reciprocating internal combustion engine according to the invention per cylinder has means for igniting the fuel-gas mixture in the combustion chamber.

For a homogeneous combustion of the fuel-gas mixture in the combustion chamber, it is advantageous if the fuel is mixed as evenly as possible with the gaseous medium. For this to be achieved, care is generally taken to ensure that the incoming gaseous medium flows as turbulently as possible within the combustion chamber. Here, two flow principles have proven successful in the prior art, namely in addition to a swirl flow and a so-called tumble flow, in which the inflowing gaseous medium forms a kind of roller with horizontally oriented axis. More specifically, the axis of the roller is aligned transversely to the stroke movement of the piston.

In order for this so-called tumble flow to form within the combustion chamber and, if possible, to be maintained up to the maximum compression of the fuel-gas mixture, the piston crown has a depression with a specially shaped depression surface.

According to the invention, the trough surface is now shaped such that it forms part of the outer surface of an elongate, substantially rotationally symmetrical body. This body is preferably an ellipsoid, a cylinder or a spherical barrel. At the same time, the longitudinal axis of the body also forms its rotational symmetry axis. Moreover, according to the invention, the longitudinal axis or rotational symmetry axis of the body is now aligned such that it extends both transversely to the stroke movement of the piston and substantially transversely to the fuel injection beam axis.

The inventive shape of the trough surface ensures in a particularly advantageous manner that forms a tumble flow in the combustion chamber. The known in the prior art substantially asymmetrically shaped troughs are therefore replaced according to the invention by a symmetrically formed trough surface. This is inventively achieved by the trough surface is formed as part of an outer surface of an elongated, substantially rotationally symmetrical body. This ensures that the tumble flow is more intense and sustained longer. Through the use of modern injectors for the introduction of air into the combustion chamber and as a result of higher injection pressures, a better atomization is achieved when using the trough according to the invention than was hitherto possible. For this reason, a shorter injection length is sufficient for mixture formation and entrainment of the smaller droplets in the gas flow, wherein the longitudinal or rotational symmetry axis of the body forming the shape of the well surface transverse to the fuel injection beam axis (and the gas inflow direction) is shorter despite shorter Length of the fuel injection jet gives a good mixture preparation. With the inventive concept, it is therefore possible to introduce the gas and the fuel transversely to the longitudinal or rotational symmetry axis of the trough surface, with the advantage that the tumble flow is intensified and maintained longer.

In a further advantageous embodiment of the invention, it is provided that the rotationally symmetrical body is substantially ellipsoidal or cylindrical or spherical and thus the trough surface is formed as part of the outer surface of an ellipsoid, a cylinder or a spherical barrel.

Alternatively, it may be advantageous if the trough surface has the shape of the surface of a groove whose depth and / or width decreases towards the two opposite axial ends.

As already mentioned above, the fuel injection jet axis is directed transversely to the axis of symmetry of the trough. It is useful if the fuel injection beam axis is aligned at an angle of at least 20 °, preferably at least 25 ° to the radial extent of cylinder or piston. The fuel can thus be introduced at a relatively shallow angle to the radial plane of extension of cylinder or piston. Basically, the angle is an acute angle and is thus between 0 ° and 90 °.

In a further expedient embodiment of the invention, it can be provided that the gaseous medium flows into the combustion chamber in an inlet flow direction and that the inlet flow direction likewise runs essentially transversely to the longitudinal axis or rotational axis of the rotationally symmetrical body defining the depression surface.

Typically, the piston crown is provided with substantially trapezoidal elevations when viewed from the side view. This results in two inclined inclined surfaces with a ridge area between these inclined surfaces. The inclined surfaces lie opposite the inlet and the outlet valves and have pinch surfaces. Accordingly, the cylinder cover wall is also provided on its underside facing the combustion chamber with two sloping sloping roofs and a ridge region between them, inlet and outlet valves being arranged in the two sloping roofs.

In the aforementioned type of piston crown, the depression is arranged centrically in the ridge region, its rotation axis length or the rotation axis of the rotation body forming the depression surface being arranged at a constant distance from the oblique surfaces of the piston crown over its length. The axis of rotation of the trough is thus approximately diametrically and rectified with the ridge region, i. h., That it extends substantially through the center of the considered over the rotation axis length largest cross-section of the rotating body.

• – mindestens einem Zylinder, der eine Zylinderwand aufweist,
• – einem in dem Zylinder auf- und abbewegbaren Kolben mit einem Kolbenboden,
• – wobei durch die Zylinderwand, den Kolbenboden und einer diesem gegenüberliegenden Zylinderdecke mit zwei schrägliegenden Dachwänden und einem Firstbereich zwischen diesen ein Brennraum gebildet ist,
• – mindestens einer Einlassöffnung mit Einlassventilen in der einen Dachwand der Zylinderdecke zum Einlassen von Luft in den Brennraum in einer Einströmrichtung und mindestens einer Auslassöffnung mit Auslassventil in der anderen Dachwand der Zylinderdecke,
• – mindestens einer Zündeinheit,
• – einem in den Brennraum einmündenden Kraftstoff-Einspritzkanal zum Einspritzen von Kraftstoff in den Brennraum längs einer Einspritzstrahlachse und
• – einer in den Kolbenboden ausgebildeten Mulde zur Unterstützung des Entstehens und Aufrechterhaltens einer Tumble-Strömung des Kraftstoff-Luft-Gemisches in dem Brennraum,
• – wobei die Mulde im Wesentlichen als Teil eines auf eine Rotationsachse bezogenen rotationssymmetrischen Körpers ausgeformt ist,
• – wobei die Rotationsachse quer zur Einspritzstrahlachse sowie im Wesentlichen quer zur Einströmrichtung der Luft in den Brennraum und ferner quer zur Hubbewegung des Kolbens verläuft.

In a preferred embodiment of the invention, this relates to a reciprocating internal combustion engine, which is provided with

• At least one cylinder having a cylinder wall,
• A piston which can be moved up and down in the cylinder and has a piston head,
• Wherein a combustion chamber is formed by the cylinder wall, the piston head and a cylindrical ceiling opposite thereto with two sloping roof walls and a ridge area between them,
• At least one inlet opening with inlet valves in the one roof wall of the cylinder ceiling for introducing air into the combustion chamber in an inflow direction and at least one outlet opening with outlet valve in the other roof wall of the cylinder ceiling,
• - at least one ignition unit,
• - An opening into the combustion chamber fuel injection channel for injecting fuel into the combustion chamber along an injection jet axis and
• A trough formed in the piston head to assist in the creation and maintenance of a tumble flow of the fuel-air mixture in the combustion chamber,
• Wherein the trough is substantially formed as part of a rotationally symmetrical body related to a rotational axis,
• - Wherein the axis of rotation is transverse to the injection axis and substantially transverse to the direction of flow of air into the combustion chamber and further transverse to the stroke of the piston.

The invention will be explained in more detail using an exemplary embodiment and with reference to the drawing. In detail, they show:

1 1 is a schematic view of a longitudinal section through a cylinder of a reciprocating internal combustion engine with adjacent structural units;

2 a plan view of the piston head of the piston in the cylinder according to 1 and

3 a sectional view through the piston along the line III-III of 2 ,

1 shows a longitudinal section through a reciprocating internal combustion engine 10 holding an engine block 12 with cylinder head mounted on it 14 having. The cylinder 16 is formed by a peripheral wall 18 and a cylinder cover wall 20 , In the cylinder 16 there is a piston 22 using a connecting rod 23 and a crankshaft (not shown) within the cylinder 16 can be moved up and down. The top of the piston 22 is from the piston crown 24 formed, which together with the peripheral wall 18 and the cylinder cover wall 20 a combustion chamber 26 forms. In the cylinder head 14 are an air supply channel 28 and a combustion gas discharge passage 30 educated. Both channels open into the combustion chamber 26 and can be optionally from at least one inlet valve 32 or exhaust valve 34 close. The channels 28 and 30 as well as valves 32 and 34 on the one hand form means 36 for introducing a gaseous medium into the combustion chamber 26 or means 38 for discharging gaseous medium from the combustion chamber 26 ,

Further, the reciprocating internal combustion engine 10 per cylinder 16 with a means 40 for injecting fuel into the combustion chamber 26 Mistake. The fuel is doing along an injection axis 42 over one into the combustion chamber 26 opening injection channel 44 injected.

Further, in particular with reference to 1 to recognize is the bottom 46 the cylinder cover wall 20 roof-shaped and with two mutually inclined sloping roofs 48 . 50 and a ridge area 52 Mistake. In the ridge area 52 is a means 54 to the combustion chamber 26 Successful ignition of the fuel-air mixture arranged.

Accordingly, the piston crown 24 also a raised, roof-shaped figure, with two inclined surfaces 56 . 58 and a ridge area 60 between them is provided.

As in 1 shown, the fuel injection jet at a relatively shallow angle, for example, 20 ° or more in the combustion chamber 26 enter. This fuel mixes with the in the combustion chamber 26 admitted air in a homogeneous manner, which is explained below.

The peculiarity of the reciprocating internal combustion engine 10 according to 1 consists in the formation of the piston crown 24 as it is in the 2 and 3 is shown. In the ridge area 60 points the piston crown 24 a hollow 62 on top, which is a trough surface 63 has the nature of a partial surface of an elongate rotationally symmetrical body whose longitudinal axis 64 forms the rotational symmetry axis. In this embodiment, the rotational body is substantially an ellipsoid, so that the trough 62 to their axially opposite ends 66 . 68 decreases in width and depth. The deepest and widest is the hollow 62 in their middle between the two axial ends 66 . 68 , The orientation of the longitudinal or rotational symmetry axis 64 of the body or the trough 62 to the fuel injection jet axis 42 (please refer 2 ) is rectangular. The longitudinal or rotational symmetry axis 64 also runs transversely to the lifting or up and down movement 70 of the piston 22 (please refer 3 ). Also in the combustion chamber 26 inflowing air flows essentially transversely to the longitudinal extension of the trough, ie transversely to the longitudinal or rotational symmetry axis 64 one. Due to the high injection pressures and the modern injector technology, the special trough shape in the manner of a part of the outer surface of a crowned barrel or of a part of the outer face of an ellipsoid makes it possible within the combustion chamber 26 a homogenization of the fuel-air mixture by preserving an intense tumble flow 72 (please refer 1 ) for as long as possible. The improved homogenization of the fuel-air mixture due to the formation of the intensive tumble flow and maintaining it during the compression process leads to a uniform combustion and thus to an improvement of the combustion process, which improves the efficiency of the reciprocating internal combustion engine and the pollutant content in the combustion gases reduced.

LIST OF REFERENCE NUMBERS

10

 Reciprocating internal combustion engine

12

 block

14

 cylinder head

16

 cylinder

18

 peripheral wall

20

 Cylinder cover wall

22

 piston

23

 pleuel

24

 piston crown

26

 combustion chamber

28

 Air supply channel

30

 Combustion gas discharge

32

 intake valve

34

 outlet valve

36

 Means for introducing gas into the combustion chamber

38

 Means to omit

40

 Means for injecting fuel into the combustion chamber

42

 Fuel injection jet axis

44

 Injection channel

46

 Bottom of the cylinder head

48

 Roof slope at the bottom of the cylinder head

50

 Roof slope at the bottom of the cylinder head

52

 First area

54

 Means for igniting

56

 Sloping surface on the piston crown

58

 Sloping surface on the piston crown

60

 First area

62

 trough

63

 trough surface

64

 Longitudinal axis or rotational symmetry axis of the body surface forming the body surface

66

 axial end of the trough

68

 axial end of the trough

70

 Up and down movement of the piston

72

 Tumble flow

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 10354682 A1 [0003]
• EP 0937890 A2 [0003]
• EP 0997622 A1 [0003]
• WO 01/49996 A1 [0003]
• US 2003/0056748 A1 [0003]
• DE 102012103195 A1 [0004]

Claims (9)

Reciprocating internal combustion engine with - at least one cylinder ( 16 ), which has a peripheral wall ( 18 ) and a cylinder cover wall ( 20 ), - one in the cylinder ( 16 ) reciprocating piston ( 22 ) with a piston bottom ( 24 ), - whereby the peripheral wall ( 18 ) of the cylinder ( 16 ) as well as its cylinder cover wall ( 20 ) and the piston crown ( 24 ) a combustion chamber ( 26 ), - means ( 36 ) for introducing a gaseous medium into the combustion chamber ( 26 ), - Medium ( 38 ) for discharging a gaseous medium from the combustion chamber ( 26 ), - Medium ( 40 ) to along an injection jet axis ( 42 ) injection of fuel into the combustion chamber ( 26 ) and - means ( 54 ) for igniting the fuel-gas mixture in the combustion chamber ( 26 ), - wherein in the piston head ( 24 ) to aid in the creation and maintenance of a tumble flow ( 72 ) of the fuel-gas mixture within the combustion chamber ( 26 ) a trough ( 62 ) with a trough surface ( 63 ), characterized in that - the shape of the trough surface ( 63 ) is formed as part of an outer surface of an elongated, substantially rotationally symmetrical body, which has a longitudinal axis which is the axis of rotation ( 64 ) of the body and the transverse to the up and down movement ( 70 ) of the piston ( 22 ), and - that the rotational or longitudinal axis ( 64 ) of the rotationally symmetrical body transversely to the fuel injection jet axis ( 42 ) runs. Reciprocating internal combustion engine according to claim 1, characterized in that the rotationally symmetrical body is substantially ellipsoidal or cylindrical or spherical and thus the trough surface ( 63 ) as part of the outer surface of an ellipsoid, a cylinder ( 16 ) or a spherical barrel is formed. Reciprocating internal combustion engine according to claim 1 or 2, characterized in that the well surface ( 63 ) has the shape of the surface of a groove whose depth and / or width decreases towards the two opposite axial ends. Reciprocating internal combustion engine according to one of claims 1 to 3, characterized in that the fuel injection jet axis ( 42 ) at an acute angle to the radial extent of cylinder ( 16 ) or piston ( 22 ) is aligned. Reciprocating internal combustion engine according to one of claims 1 to 4, characterized in that the gaseous medium in an inlet flow direction in the combustion chamber ( 26 ) and that the inlet flow direction is also substantially transverse to the longitudinal axis or axis of rotation of the well surface ( 63 ) defining rotationally symmetrical body runs. Reciprocating internal combustion engine according to one of claims 1 to 5, characterized in that the cylinder cover wall ( 20 ) at its the piston ( 22 ) opposite underside two inclined roof pitches ( 48 . 50 ) with a ridge area ( 52 ) between them and that the funds ( 36 . 38 ) for introducing and discharging gaseous medium into and out of the combustion chamber ( 26 ) in the roof slopes ( 48 . 50 ) of the cylinder cover wall ( 20 ) are arranged. Reciprocating internal combustion engine according to one of claims 1 to 6, characterized in that the piston head ( 24 ) has a roof-shaped raised top, the two inclined inclined surfaces ( 56 . 58 ) and a ridge area ( 52 ) between these inclined surfaces ( 56 . 58 ), and that the trough ( 62 ) centric in the ridge area ( 60 ) of the top of the piston crown ( 24 ) with the same distance from the inclined surfaces ( 56 . 58 ) is arranged. Reciprocating internal combustion engine according to one of claims 1 to 6, characterized in that the piston head ( 24 ) has a roof-shaped raised top, the two inclined inclined surfaces ( 56 . 58 ) and a ridge area ( 52 ) between these inclined surfaces ( 56 . 58 ), and that the axis of rotation ( 64 ) of the trough ( 62 ) approximately at the level of the midpoint of the largest cross section of the trough surface ( 63 ) and rectified with the longitudinal extent of the ridge region ( 60 ) runs. Reciprocating internal combustion engine according to claim 6 and 8 or 7 and 8, characterized in that the inclined inclined surfaces ( 56 . 58 ) of the top of the piston crown ( 24 ) the roof slopes ( 48 . 50 ) of the cylinder cover wall ( 20 ) in pairs opposite.

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