DE102010038533A1 - Lifting cylinder combustion engine, has combustion chambers with pistons movably arranged in cylinders, where one chamber is provided for operating point for small load, and other chamber is provided for operating point for large load - Google Patents

Abstract

The engine has two combustion chambers with two pistons movably arranged in two cylinders, respectively, where a fuel/air mixture is combustible in the chambers. A gas changing inlet valve and a gas changing exhaust valve are provided in each cylinder for exchanging gas. One of the chambers is provided for an operating point for a small load, and the other chamber is provided for an operating point for a large load. The former chamber exhibits large compression ratio than the latter chamber, and the cylinders are operated simultaneously or independently.

Description

The invention relates to a reciprocating internal combustion engine with the features of the preamble of patent claim 1.

The technical environment, for example, the German patent application DE 26 18 962 A1 pointed. From this disclosure, a combustion apparatus for an internal combustion engine is known, which has an exhaust gas recirculation system in which a lean air-fuel mixture can be used without aggravating the combustion. The combustion chamber is divided into two individual chambers and the combustion is carried out successively in the individual chambers. An ignition of the air-fuel mixture in the second chamber takes place by a flame from the first chamber as a flare ignition.

A similar internal combustion engine is known from German Offenlegungsschrift DE 26 47 091 A1 known. From this, a mixture-compressing reciprocating internal combustion engine with at least one each enclosed between a piston and a cylinder or cylinder head combustion chamber is known, which is divided into at least two partial combustion chambers, which are separated in the vicinity of the top dead center of the piston stroke and during the remaining time of the Piston strokes are interconnected, the ignition takes place in the individual partial combustion chambers in succession. Further, it is known from this publication, that in such a design of the piston and cylinder of the internal combustion engine, the compression ratio is equal to or greater than 12 at least in the one or more later in the ignition coming partial combustion chambers. Due to the fact that the compression ratio is increased above the previously permissible compression ratios at least in the partially ignited partial combustion chambers, the thermal efficiency of the internal combustion engine is significantly increased, in particular in the partial load region, where the compression ratios remain below the compression end values due to the small cylinder charge anyway. But even at full load, these compression ratios can be maintained without disadvantage at least in the coming to ignition partial combustion chambers, since the ignition occurs there only at a time in which the maximum caused by the piston compression is already exceeded. The risk of knocking combustion is thus largely eliminated.

Next are from the German patent application DE 10 2005 024 058 A1 an internal combustion engine and a method for operating an internal combustion engine. The internal combustion engine has at least one movable piston, in particular a reciprocating piston or rotary piston, a housing at least partially surrounding the piston, in particular with a cylindrical or trochoidenförmigen Gehäuseinnenwandung and arranged between the piston and the housing, can be compacted by the movement of the piston combustion chamber or working space, in which a supplied fuel-air mixture is ignited. This internal combustion engine is characterized in that the combustion chamber or working space is geometrically designed so that a maximum geometric compression is achieved by the movement of the piston, which is higher than the usable in full load operation of the internal combustion engine compression.

A disadvantage of the above-mentioned prior art, the fissured combustion chamber, which in particular during warm-up of the engine, the HC emissions are high.

A disadvantage of the last-mentioned prior art is that variable compression ratios can be realized only with great difficulty.

Object of the present invention is to show an alternative reciprocating internal combustion engine whose efficiency is significantly improved over a conventional reciprocating internal combustion engine.

This object is achieved by the feature in the characterizing part of patent claim 1.

Due to the configuration according to the invention, an improvement in the efficiency of the internal combustion engine achieves a consumption advantage over conventional internal combustion engines, since each cylinder can be operated at its optimized operating point.

Preferred embodiments of the invention are set forth in the subclaims.

The embodiment according to claim 2 is a preferred way to achieve the solution of the invention to the task.

The compression ratios according to claim 3 are particularly suitable for this purpose.

The load ranges according to claim 4 are also particularly preferred ranges.

A further fuel economy through improved efficiency is achieved with a design according to claim 5.

The embodiment according to claim 6 allows a cylinder shutdown and leads to a further fuel economy.

The embodiments acc. The claims 7 and 8 again increases the overall efficiency of the reciprocating internal combustion engine according to the invention.

In the following the invention will be explained in more detail with reference to two figures for two particularly preferred embodiments.

1 FIG. 2 is a graph showing two numerically calculated load curves for a dual combustion chamber internal combustion engine whose first combustion chamber is designed for a small load (A) operating point and whose second combustion chamber is designed for a large load (B) operating point over a sum of a total load internal combustion engine.

2 shows in a diagram two numerically calculated load curves for a combustion engine according to the invention with two combustion chambers, the first combustion chamber for a small load operating point (A) and the second combustion chamber for a high load operating point (B) are designed over a sum of a total load the internal combustion engine, wherein the first cylinder and the second cylinder are operated at a mean pressure We _ges <1 kJ / dm ³ with different mean pressures.

• • Sie charakterisiert die mechanische und thermische Beanspruchung der Brennkraftmaschine einschließlich ihrer Lastzustände zwischen Leerlauf und Volllast.
• • Sie ermöglicht bei einer Gegenüberstellung der je Hubraumeinheit gewonnen Arbeit eine Einschätzung zum Entwicklungsstand der Brennkraftmaschine.

To explain a mean pressure in a combustion chamber of an internal combustion engine:
The required for the drive purpose work in a working cycle of an internal combustion engine can be generated both from a cylinder with a larger and smaller displacement. This work is a great burden for a cylinder with a small displacement, the same work means a lower load for a cylinder with a large displacement. This load has a meaning in two ways:

• • It characterizes the mechanical and thermal load of the internal combustion engine including its load conditions between idle and full load.
• • It allows for a comparison of the work won per displacement unit work an assessment of the state of development of the internal combustion engine.

Wi

= indizierter Mitteldruck

Wi_hA

= ermittelte initiierte Arbeit

V_hA

= Hubvolumen

The work won per working cycle and based on the stroke volume work is the specific work of the internal combustion engine, which is known under the term energy density or medium pressure. If the determined initiated work is related to the effective cylinder stroke volume in the working cycle, the indicated energy density (indexed mean pressure) results: Wi = Wi _hA / V _hA [kWs / m ³ ] or [kJ / dm ³ ] With:

wi

= indicated mean pressure

Wi _hA

= identified initiated work

V _hA

= Stroke volume

From the consideration of the units it can be seen why the specific work can also be understood as pressure: It is the imaginary, mean pressure, which informs the piston of the indicated work during a stroke in the working cycle.

We

= effektiver Mitteldruck

We_hA

= effektive Arbeit

V_hA

= Hubvolumen

Analogous to the indexed energy density, further specific works (mean pressures) are given:
With the work per effective working cycle at the engine clutch (effective medium pressure): We = We _hA / V _hA [kWs / m ³ ] or [kJ / dm ³ ] With:

We

= effective medium pressure

We _hA

= effective work

V _hA

= Stroke volume

Next applies in the following: We _ges = We _total

The design of the compression ratio in known reciprocating internal combustion engines is normally carried out for full load operation, which has the disadvantage that in part-load operation, the efficiency is lower due to the lower effective compression than in full load operation.

In order to improve the efficiency of internal combustion engines, in particular in part-load operation, it is known, for example, to control a variable compression of the combustion air or a fuel-air mixture.

In this case, as already shown above, design solutions are used, for example, increase the rotating and / or oscillating masses of the crank mechanism in a negative way or overall complex structure of the crank mechanism result or have the unfavorable, fissured combustion chambers (slave piston) and thus the pollutant emissions increase.

Compared to this known prior art is therefore inventively proposed that the first combustion chamber of a multi-cylinder internal combustion engine for an operating point for a small load (A) and the second combustion chamber for an operating point for a large load (B) are designed.

In this case, the first combustion chamber particularly preferably has a greater compression ratio than the second combustion chamber, with the first combustion chamber preferably having a compression ratio greater than 10 and the second combustion chamber having a compression ratio of less than 10. Furthermore, the first cylinder is operable to a load of W _e = 1 kJ / dm ³ to 1.5 kJ / dm ³ and the second cylinder to a load of W _e = 3 kJ / dm ³ to 4 kJ / dm ³ , A further improvement of the efficiency results from the fact that a charging device is provided for the second cylinder. In a particularly preferred embodiment, the first cylinder and the second cylinder are simultaneously also at a W _e total <1 kJ / dm ³ with different mean pressures ( 2 ) operable.

In a further development of the reciprocating internal combustion engine according to the invention, different charging devices can be provided for the first cylinder and the second cylinder. Here, for example, different sized exhaust gas turbocharger or an exhaust gas turbocharger and a compressor can be provided. In a particularly advantageous development, the charging device for the second cylinder also uses the exhaust gas energy from the first cylinder.

In a further embodiment, the reciprocating internal combustion engine according to the invention may also have more than two combustion chambers. Also, it does not matter if the reciprocating internal combustion engine is in Reihenbauart or V-type. It may also be an Otto engine or diesel engine combustion process.

1 2 shows in a first diagram two numerically calculated load curves for an internal combustion engine with two combustion chambers whose first combustion chamber is designed for a low load operating point (A) and whose second combustion chamber is designed for a high load operating point (B) (Y-axis, We _Zyl.Abzw.B ) over a sum of a total load of the internal combustion engine (X-axis, We _total ), shown.

The effective mean pressure of the entire reciprocating internal combustion engine is plotted in a range from 0 to 2.5 [kJ / dm ³ ] over the X-axis. In this embodiment, the effective medium pressure for the reciprocating internal combustion engine increases linearly from 0 to 1 [kJ / dm ³ ], while then the effective mean pressure of the combustion chamber for the operating point for the small load (A) constant at 1 [kJ / dm ³ ] remains. The effective mean pressure for the second combustion chamber for the operating point for the large load (B), however, increases up to 3 [kJ / dm ³ ]. The effective mean pressure of the entire reciprocating internal combustion engine is the sum of the two effective individual pressures of the two combustion chambers divided by 2.

2 shows in a second diagram, two numerically calculated load curves for a reciprocating internal combustion engine according to the invention with two combustion chambers, the first combustion chamber for a small load operating point (A) and the second combustion chamber for a large load operating point (B). are arranged (Y axis We _Zyl.Abzw.B) over a sum of a total load of the reciprocating piston internal combustion engine (X-axis We _total), wherein the first cylinder and the second cylinder at the same time even with a _saturated We <1 kJ / dm ³ are operated with different mean pressures.

It can clearly be seen that in the low load range, the effective mean pressure of the combustion chamber for the operating point for the small load (A) is significantly higher than for the second combustion chamber for the large load (B) up to a path of 1 [kJ / dm ³ ]. Thereafter, the effective mean pressure of the combustion chamber designed for the large load (B) increases linearly while the effective mean pressure for the first combustion chamber designed for the small load (A) again becomes constant at 1 [kJ / dm ³ ] remains.

It follows that the reciprocating internal combustion engine according to the invention up to a We _ges of 1.0 [kJ / dm ³ ] predominantly with the combustion chamber for the low load (A) and beyond to a We _ges of 3.0 [kJ / dm ³ ] predominantly with the combustion chamber is designed for the large load (B), is operated. This results in the greatest possible fuel economy.

In other words:
According to a differentiation of the cylinder of the reciprocating internal combustion engine according to purpose, z. B. as part load and full load cylinder. The part-load cylinders preferably cover the load range up to z. W _e = 1 [kJ / dm ³ ], the full-load cylinder the range to W _e = 3 [kJ / dm ³ ] from. This differentiation may further include: compaction, e.g. B. 13 in the partial load cylinders and 10 in the full load cylinders. Also injection (direct injection, intake manifold injection etc.), valve control, charge, etc. may differ.

Furthermore, it may be advantageous to select the operating strategy such that the cylinders are preferably used in their "special area" ( 2 ). An even greater fuel economy can be achieved with a cylinder shutdown by the cylinder B below z. B. We _ges = 0.5 [kJ / dm ³ ] are switched off ( 2 with extended B-line).

Due to the inventive design results in fuel efficiency advantage due to an improvement in the efficiency of the internal combustion engine.

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 2618962 A1 [0002]
• DE 2647091 A1 [0003]
• DE 102005024058 A1 [0004]

Claims (8)

Reciprocating internal combustion engine having at least a first and a second cylinder, wherein in the first cylinder, a first piston and in the second cylinder, a second piston is arranged liftably, wherein a first combustion chamber of the first piston, the first cylinder and a first combustion chamber roof and a second combustion chamber is formed by the second piston, the second cylinder and a second combustion chamber roof, in each of which a fuel / air mixture is combustible, wherein for each cylinder for a gas exchange at least one Gaswechseleinlass- and a Gaswechselauslassventil is provided, characterized in that the first combustion chamber is designed for one operating point for a small load (A) and the second combustion chamber for a working point for a large load (B). Reciprocating internal combustion engine according to claim 1, characterized in that the first combustion chamber has a greater compression ratio than the second combustion chamber. Reciprocating internal combustion engine according to claim 2, characterized in that the first combustion chamber has a compression ratio greater than 10 and the second combustion chamber at the compression ratio is less than 10. Reciprocating internal combustion engine according to one of the claims 1 to 3, characterized in that the first cylinder up to a load of w _e = 1 kJ / dm ³ to 1.5 kJ / dm ³ and the second cylinder up to a load of w _e = 3 kJ / dm ³ to 4 kJ / dm ^{3 is} operable. Reciprocating internal combustion engine according to one of the claims 1 to 4, characterized in that a charging device is provided for the second cylinder. Reciprocating internal combustion engine according to one of the aforementioned claims, characterized in that the first cylinder and the second cylinder are operated simultaneously or independently of each other. Reciprocating internal combustion engine according to claim 5 or 6, characterized in that different charging devices are provided for the first cylinder and the second cylinder. Reciprocating internal combustion engine according to one of the claims 5 to 7, characterized in that the charging device for the second cylinder also uses an exhaust gas energy from the first cylinder.

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