DE102015004688A1 - Piston crown with injector pocket for combustion engines - Google Patents

Abstract

The present disclosure relates to a piston crown (110) for internal combustion engines with a liquid fuel injector. The piston crown may have a piston skirt surface (114) and a piston crown (116) bounding the piston skirt surface (114). The piston head (116) can be formed from a piston bottom edge (118) and a piston bottom recess (120). The piston crown (110) may further include an injector pocket (132) formed in the piston bottom edge (118). The injector pocket (132) may transition into the piston bottom well (120) via rounded edges (135, 136, 137) having predetermined radii and may be configured to provide an increased fuel jet path for the liquid fuel injector.

Description

Technical area

The present disclosure relates to a piston crown and a piston for internal combustion engines.

background

Pistons for internal combustion engines may include a piston skirt attachable to a piston crown and a piston rod. The piston crown defines a combustion chamber together with a cylinder or cylinder liner in which the piston reciprocates and the cylinder head.

The piston crown has an outer surface which is bounded at its upper end by the piston crown. A piston bottom edge and a piston bottom recess can form the piston crown. The piston bottom recess at least partially forms the combustion chamber.

For example, pistons can be used with a variety of designs of the piston crown in gasoline engines. Therefore, with respect to gas-fuel burned pre-combustion chamber burns, there are pistons having roof-shaped piston bottoms configured to strike the combustion flames against the pre-combustion chamber walls as late as possible. Furthermore, there are pistons with trough-shaped piston bottoms, which are designed to maintain a tumble flow generated at the inlet. In addition, there are pistons having an omega-shaped piston crown with a piston crown adapted to be designed for diesel operation with optimized direct injection and used unchanged in a gaseous fuel gasoline engine for cost and simplicity. The latter regardless of a possibly reduced combustion efficiency. Further, there are cup-shaped piston-type recesses designed to create a squish flow in the radial direction between the piston edge and the cylinder head. In addition, a swirling flow in the cup-shaped piston crown can be enhanced.

Pistons with cup-shaped piston bottom wells are well suited for engines with swirling intake ports and chamber candles. During the compression stroke, the mixture can be brought into the cup-shaped piston bottom well via the piston bottom ring (squish flow) of the piston. During the working cycle, the mixture is sucked back into the pot-shaped piston bottom mold. This process results in very strong squish flows, especially near top dead center.

In addition to the squish flow, the cup-shaped piston bottom well also leads to an acceleration of the turbulence generated at the inlet. Due to the conservation of momentum, the rotational velocity of the vortex flow increases as the mixture is brought inwardly into the cup-shaped piston crown.

Furthermore, dual-fuel engines are known, either with a liquid fuel such. As heavy oil or diesel oil, or with a gaseous fuel such. As natural gas, operated. During the liquid fuel mode, the combustion mixture is usually ignited with a spark plug. During the gaseous fuel mode, the combustion mixture may be injected by injecting a small quantity of a self-igniting liquid fuel, such as a liquid fuel. B. diesel fuel that ignites due to the pressure in the engine to be ignited. The ignited small amount of self-igniting liquid fuel in turn ignites the combustion mixture of gaseous fuel and air.

DE 10 2010 018 930 A1 discloses a piston for an internal combustion engine with four valve seat pockets that ensure quiet operation of the intake and exhaust actuator valves.

DE 10 2012 103 212 A1 discloses a piston for an internal combustion engine having a piston crown with a predetermined depth and a plurality of valve seat pockets, each having a predetermined depth, wherein there is a predetermined relationship between the piston head depression depth and the valve seat pocket depths.

US 4,370,958 A discloses a method of operating an air compressing auto-ignition engine for liquid fuel. A piston disclosed therein has a combustion chamber cavity. The engine has a first injector for injecting oxygen-containing fuel, which is difficult to ignite, and a second injector for injecting, which is ready to ignite, such as such. B. diesel fuel. In order for the injection flow into the combustion chamber cavity to occur unhindered for each crank angle position, the piston crown or crown has a depression in the region of the first injection device.

The present disclosure is directed to at least partially alleviate or overcome one or more aspects of prior systems.

Summary of the Revelation

According to one aspect of the present disclosure, a piston crown for internal combustion engines is disclosed with a liquid fuel injector removed from a cylinder axis and disposed at a predetermined angle to the cylinder axis. The liquid fuel injector may be configured to inject a predetermined amount of liquid fuel along a fuel jet path. The disclosed piston crown may have a piston skirt surface with a central axis and a piston crown defining the piston skirt surface. The piston head may be formed with a piston bottom edge and a piston bottom recess. The disclosed piston crown may further include an injector pocket formed in the piston bottom edge. The injector pocket may transition into the piston bottom well and may be configured to provide an increased fuel jet path for the liquid fuel injector. The injector pocket may transition into the piston bottom well via rounded edges having predetermined radii.

In another aspect of the present disclosure, a piston for internal combustion engines is disclosed. The piston may include a piston skirt and a piston crown according to the present disclosure. The piston crown can be attached to the piston skirt.

Brief description of the drawings

1 shows a plan view of a piston crown of a piston for an internal combustion engine.

2 shows a sectional view through the piston along the line II-II of 1 ,

3 shows a further sectional view through a piston with another design of an injector pocket.

Detailed description

The following is a detailed description of exemplary embodiments of the present disclosure. The exemplary embodiments described herein and shown in the drawings are intended to teach the principles of the present disclosure to enable one skilled in the art to implement and use the present disclosure in a variety of environments and for many different applications. Therefore, the exemplary embodiments are not intended to and should not be considered as a limiting description of the scope of the patent protection. Instead, the scope of patent protection should be defined by the appended claims.

According to the present disclosure, an outwardly curved surface, with respect to a reference axis in a reference plane perpendicular to the reference axis, means that the surface is substantially convex when viewed from the reference axis in the reference plane. In contrast, an inwardly curved surface with respect to a reference axis viewed in a plane perpendicular to the reference axis means that the surface is substantially concave when viewed from the reference axis in said reference plane.

According to the present disclosure, a pocket describes a depression formed in a body. The bag has a side surface and a bottom surface that limits the side surface. The bottom surface of the bag may be provided in any suitable manner and shape. For example, the bottom surface may be planar, partially curved, partially oblique to the side surface, or may have any other suitable shape.

The present disclosure may be based in part on the insight that providing an injector pocket in a piston crown of a piston crown having rounded edges may increase a fuel jet path for liquid fuel injected by a liquid fuel injector. In addition, by providing rounded edges at the junctions between the injector pocket and the piston crown, a combustion chamber formed at least partially by a piston bottom cavity and the injector pocket may be provided which communicates the combustion lines of the combustion mixture, such as air. As a mixture of gaseous fuel and air, which was ignited by injecting a pilot fuel, smooth leads. In particular, the combustion chamber has a substantially convex shape with few undercuts. In addition, the edges at the junctions between the injector pocket and the piston bottom edge and between the piston bottom recess and the piston bottom edge may be provided with curves and / or bevels for further smoothing of the combustion chamber.

By providing a smooth and substantially convex combustion chamber, any turbulence and turbulence that would be affected by sharp edges can be reduced, which can lead to a more homogeneous combustion mixture in the combustion chamber. Accordingly, emissions can be reduced and the efficiency of the combustion process improved.

An exemplary piston 100 for internal combustion engines is in the 1 and 2 shown. The piston 100 has a piston crown 110 and a piston shirt 140 on. The piston crown 110 is removable on the piston skirt 140 with at least one screw 102 appropriate. The piston 100 is adapted to be guided in a cylinder or a cylinder liner of an internal combustion engine back and forth. For example, the internal combustion engine may include a gaseous fuel gasoline engine, a diesel engine, a dual-fuel engine operable with liquid fuel and gaseous fuel, and an engine having e.g. B. heavy oil, diesel fuel or gaseous fuel operable ternary engine.

The piston crown 110 has a piston skirt surface 114 , which revolve around a central axis 112 extends, and a piston crown 116 , the piston skirt surface 114 bounded on its top, on. The piston bottom 116 is from a piston bottom edge 118 and a piston bottom tray 120 shaped coaxially with respect to the central axis 112 are arranged. The piston bottom recess 120 has a Kolbenbodenmuldensteg 122 holding the piston bottom 120 bounded at its bottom end, and a piston bottom trough wall 124 next to the piston crown well web 122 on. The piston bottom recess 120 at least partially forms a combustion chamber.

The piston 100 According to the drawings of the present disclosure, it is configured to be in an internal combustion engine having two inlet valve valves 12 . 14 (indicated by dashed lines) per cylinder and two Auslassstellerventilen 16 . 18 (indicated by dashed lines) to be used per cylinder. Accordingly, in some embodiments, the piston crown 116 a valve seat unit (not shown in the drawings) with at least one valve seat pocket for each inlet and outlet actuator valve 12 . 14 . 16 . 18 exhibit. In some other embodiments, the internal combustion engine may include more or less than four poppet valves 12 . 14 . 16 . 18 exhibit.

Each valve seat pocket is adapted when the piston 100 at top dead center, at least partially an associated poppet valve 12 . 14 . 16 . 18 take.

The piston crown 110 also has an injector pocket 132 on that in the piston bottom edge 118 is shaped. The injector bag 132 goes into the piston bottom recess 120 and is configured to at least partially form an area of a combustion chamber. As in 1 shown is the injector pocket 132 centrally between two adjacent poppet valves 12 . 18 arranged. However, in other embodiments, the injector pockets may be 132 closer to one of the two adjacent poppet valves 12 . 18 be positioned.

With reference to 2 is a sectional view of the piston 100 along a line II-II of 1 shown. In 2 is an area of a cylinder head 11 (indicated by dashed lines) shown. A main fuel injector 150 (indicated by dashed lines) and a Zündkraftstoffinjektor 152 (indicated by dashed lines) are on the cylinder head 11 attached. The main fuel injector 150 is adapted to a predetermined amount of fuel, such. As heavy oil, in the combustion chamber, at least partially from the piston crown 120 is shaped to inject. The main fuel injector 150 is adapted to the fuel along a cylinder axis 10 which is essentially the central axis 112 is aimed to inject.

The pilot fuel injector 152 is adapted to a predetermined amount of a fuel in the combustion chamber, such as. B. inject a self-igniting fuel such as diesel fuel. The pilot fuel injector 152 is further adapted to ignite the pilot fuel along a fuel jet path 154 (indicated by dashed lines) inject substantially along an axis 156 extends. As in 2 shown is the axis 156 with respect to the central axis 112 inclined by an angle α.

To ensure that the predetermined amount of from the pilot fuel injector 152 injected ignition fuel can enter the combustion chamber unhindered, the injector pocket 132 provided at a position substantially the position of the pilot fuel injector 152 equivalent. In particular, the injector pocket 132 designed to increase the space for the fuel jet path 154 provided. In the exemplary in the 1 and 2 embodiment shown has the injector pocket 132 a lateral surface 133 and a substantially planar injector tab 134 up, perpendicular to the central axis 112 is.

As in 1 shown is the lateral surface 133 at its two ends in the Kolbenkronenmuldenwand 124 with rounded edges 135 . 136 above. The rounded edges l35 . 136 connect the piston bottom well wall 124 and the side surface 133 smooth. For example, the rounded edges 135 . 136 have predetermined radii.

Furthermore, the Injektortaschensteg goes 134 into the piston bottom cupboard 124 over a rounded edge 137 above. The rounded edge 137 connects the piston bottom well wall 124 and the Injektortaschensteg 134 smooth. Accordingly, the injector bag goes 132 into the piston bottom recess 120 over the rounded edges 135 . 136 . 137 with predetermined radii over.

In a further embodiment, in a sectional plane perpendicular to the central axis 112 a section line of the injector pocket 132 tangential in a section line of the piston crown 120 pass. With such a geometry of the injector pocket 132 with reference to the piston bottom recess 120 It can be ensured that the combustion chamber has no undercuts and therefore is provided in a round and convex shape to reduce turbulence and turbulence, which are transferred to the combustion mixture. In such a case, in a plan view, the injector pocket 132 together with the piston bottom recess 120 a cam shape in which the injector pocket 132 can form the cam.

As further in the 1 and 2 can be seen have the injector pocket 132 and the piston bottom tray 120 round edges with radii R1 to R6. The radii R1 to R6 may range from about 5 mm to about 15 mm. Alternatively, instead of providing rounded edges, the edges at the transitions between the piston bottom edge 118 , the piston bottom recess 120 and the injector pocket 132 be provided with slopes for smoothing the transitions.

As in 2 shows the piston crown 120 a height h in the range of about 5 mm to about 40 mm. Furthermore, the injector pocket 132 a depth T ranging from about 10% to about 80% of the height h of the piston crown 120 on. A ratio of the height h of the piston crown 120 with respect to a diameter D of the piston crown 116 or the piston 100 is in the range of about 0.03 to about 0.2, wherein the diameter D is in the range of about 180 mm to about 500 mm. A ratio of a diameter d of the piston crown 120 with respect to the diameter D of the piston crown 116 is in the range of about 0.3 to about 0.8. The radii R1 and R2 are in the size of about 10% to about 40% of the diameter D of the piston crown 116 ,

The injector bag 132 may have a predetermined volume of from about 1% to about 20% of a volume of the piston crown 120 exhibit. In such a case, the injector pocket 132 relatively small in comparison to the piston bottom tray 120 be. For example, the injector pocket 132 a section in the piston bottom cupboard wall 124 for local enlargement of the fuel jet path 154 be.

3 shows a further embodiment of the injector pocket 132 , Accordingly, the Injektortaschensteg 134 have a normal at an angle β with respect to the central axis 112 is inclined. The angle β may be in a range of about 1 ° to about 25 °, the depth T with the progress of the piston crown 120 increases. Instead of an injector tab 134 to be provided, which is substantially planar and / or inclined with respect to the central axis 112 is, the injector tab can 134 be provided in a rounded shape, preferably by a rounding to provide a convex combustion chamber. That means that the rounded injector tab web 134 outward with respect to the central axis 112 is curved.

As previously described, the injector pocket 132 flat, concave, convex or all combinations thereof. The normals of the injector tab 134 represents at least a portion or only one point of the injector tab web 134 represents.

As in the 2 and 3 shows the piston crown 110 at least a portion of an outer cooling channel 142 of the piston 100 and at least a portion of an inner cooling chamber 144 of the piston 100 on. The inner cooling chamber 144 is with the outer cooling channel 142 over a plurality of cooling holes 146 fluidly connected. The section of the outer cooling channel 142 is at least partially below the piston bottom edge 118 and at least partially below the Injektortaschenstegs 134 provided and adapted, at least partially, the piston bottom edge 118 and the injector tab 134 to cool. The inner cooling chamber 144 is below the piston crown well web 122 arranged and adapted to the Kolbenbodenmuldensteg 122 to cool. The outer cooling channel 142 Can be used as an outer shaker, and the inner cooling chamber 144 can be called an inner shaker.

In further embodiments, the outer cooling channel 142 be provided with cooling holes leading to a bore cooled piston.

Industrial Applicability

For example, the ignition fuel injector injects 152 during a gaseous fuel mode of a dual-fuel internal combustion engine, a predetermined amount of ignition fuel, such. As diesel fuel, in the combustion chamber. Upon reaching a predetermined pressure in the combustion chamber during the compression stroke ignites the pilot fuel, which then a on the Inlet poppet valves 12 . 14 , ignited in the combustion chamber supplied combustion mixture.

By providing rounded edges 135 . 136 . 137 with predetermined radii R2 to R6, the streamlines of the combustion mixture, such as. As a mixture of gaseous fuel and air, along the surfaces of the injector pocket 132 and the piston bottom tray 120 run without demolition, whereby substantially a laminar flow is maintained. Thus, turbulence and turbulence that would be affected by sharp edges would decrease, such that the combustion mixture would decrease by providing rounded edges 135 . 136 . 137 can be more homogeneous.

With the exemplified piston crown, a higher compression ratio can be achieved, such. Due to the rounded edges with the predetermined radii, local hot spots can be avoided and the risk of knocking can be reduced, resulting in more efficient and complete combustion.

Further, by providing smooth transitions between the injector pocket and the piston crown, the optimal turbulence of the gaseous combustion mixture can only be somewhat affected and can essentially retain its laminar flow. This can lead to optimized and more complete combustion, which can then lead to lower emissions and higher combustion efficiency.

Although the preferred embodiments of the invention have been described herein, improvements and modifications may be practiced without departing from the scope of the following claims.

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 102010018930 A1 [0008]
• DE 102012103212 A1 [0009]
• US Pat. No. 4,370,958 A [0010]

Claims (10)

Piston crown ( 110 ) for internal combustion engines with a liquid fuel injector ( 152 ), which depends on a cylinder axis ( 10 ) spaced apart and at a predetermined angle (α) with respect to the cylinder axis ( 10 ), wherein the liquid fuel injector ( 152 ) is adapted to a predetermined amount of liquid fuel along a Kraftstoffjetpfads ( 154 ), with a piston skirt surface ( 114 ) with a central axis ( 112 ), the piston skirt surface ( 114 ) limiting piston crown ( 116 ), the piston crown ( 116 ) with a piston bottom edge ( 118 ) and a piston bottom trough ( 120 ) and an injector pocket ( 132 ), which in the piston bottom edge ( 118 ), wherein the injector pocket ( 132 ) in the piston bottom cavity ( 120 ), and is adapted to an enlarged fuel jet path ( 154 ) for the liquid fuel injector ( 152 ), the injector pocket ( 132 ) in the piston bottom edge ( 120 ) over rounded edges ( 135 . 136 . 137 ) merges with predetermined radii (R2, R3, R4, R5). Piston crown ( 110 ) according to claim 1, wherein in a sectional plane perpendicular to the central axis ( 112 ) a section line of the injector pocket ( 132 ) tangentially in a line of intersection of the piston crown ( 120 ) passes over. Piston crown ( 110 ) according to one of the preceding claims, further comprising at least one valve seat pocket which is located in the piston bottom edge ( 118 ) is formed and is formed when the piston ( 100 ) at top dead center, at least partially a poppet valve ( 12 . 14 . 16 . 18 ) of the internal combustion engine. Piston crown ( 110 ) according to claim 3, wherein the injector pocket ( 132 ) is arranged between two adjacent valve seat pockets, preferably arranged centrally between two adjacent valve seat pockets. Piston crown ( 110 ) according to one of the preceding claims, wherein the injector pocket ( 132 ) has a volume in the range of about 1% to about 20% of a volume of the piston crown ( 120 ) having. Piston crown ( 110 ) according to one of the preceding claims, wherein in a sectional plane perpendicular to the central axis ( 112 ) a section line of the injector pocket ( 132 ) has at least a portion of a circular section line. Piston crown ( 110 ) according to one of the preceding claims, wherein the injector pocket ( 132 ) an injector tab ( 134 ) having at least one portion perpendicular to the central axis ( 112 ). Piston crown ( 110 ) according to one of the preceding claims, wherein the injector pocket ( 132 ) an injector tab ( 134 ) having at least one portion extending at a predetermined angle (β) with respect to the central axis ( 112 ). Piston crown ( 110 ) according to one of the preceding claims, wherein a diameter (D) of the piston crown ( 116 ) is in a range of about 180 mm to about 50 mm. Piston ( 100 ) for internal combustion engines with a piston skirt ( 140 ) and a piston crown ( 110 ) according to one of the preceding claims, wherein the piston crown ( 110 ) on the piston skirt ( 140 ) is attached.

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