DE102005044503A1 - Internal combustion engine, comprises piston designed as double-diameter piston or as deflector piston - Google Patents

Abstract

The engine is equipped with a cylinder (1) accommodating a piston (3) with several projections located at the crown. In a first version the piston (3) is designed as a double diameter piston with a concentrically arranged step (4) forming two chambers (7,8) connected by overflow ducts (9) at the cylinder (1) in combination with the projections at the crown. The piston (3) is designed as a deflector piston in a second version, with pre-chambers at both deflectors, each fitted with an injection nozzle.

Description

The The invention relates to an internal combustion engine in reciprocating design with at least one piston arranged inside a cylinder, which is configured on its piston crown with projections, the with configured in the cylinder head contours so in operative connection stand that in the upper cylinder area as a result of the movement of the Pistons between the piston and the cylinder two spaces formable are, these spaces each having a different compression ratio and by overflow such connected to each other at the end of the compression stroke Air from the as antechamber with higher Pressure trained a space through the transfer ports into the main combustion chamber pressed with lower pressure other room is pressed.

Internal combustion engines in reciprocating design are available in various designs known, where for an effective and ecological acceptable operation in particular the parameters performance, cost-effectiveness and pollutant emission are essential. In addition to other factors will therefor aiming for optimal fuel treatment and combustion for the already numerous technical solutions have been proposed.

So will in DE 111 896 describes an internal combustion engine with a stepped piston whose stepped contour is in operative connection with a contour formed in the cylinder head in such a way that between the piston and cylinder in the upper cylinder area an annular and a cup-shaped space is formed with different compression ratios. These spaces are interconnected by overflow channels into which fuel is injected. Thus, towards the end of the compression stroke air is forced out of the annular space into the overflow channel by the movement of the piston, which promotes the fuel located in the overflow channel into the pot-shaped space and simultaneously atomises it.

A similar technical solution is the subject of DE 201 155 , In one embodiment, this piston is not designed as a stepped piston, but has a circumferential annular ridge on the piston crown.

US 2 222 441 describes a further internal combustion engine, in which are formed by a combination of gradations on the piston head with recesses in the cylinder head separate and interconnected by overflow chambers spaces each having a different compression ratio.

An internal combustion engine with a graduated piston and a cylinder section congruent thereto is also made DE 37 06 592 A1 known. Also with this construction, two separate and interconnected by overflow channels spaces each having a different compression ratio are formed towards the end of the compression stroke. Here, the one room is filled with ignitable mixture, while the other room is effective as a bubble room. At the same time, a stratified charge effect can be achieved via an additional air supply pipe or a similar component.

A Schichtladeeffekt can also with an internal combustion engine according to DE 29 01 815 A1 will be realized. It is possible by using a second inlet valve in conjunction with a stepped piston, regardless of the use of a crankcase pump for applying the first inlet valve to create a completely separate second inlet tract. This second intake tract is supplied with a rich fuel-air mixture via an annular space, which is formed by contours of stepped piston and cylinder head in operative connection with one another, with which a stratified charge can be generated in the combustion chamber.

The named technical solutions resulting from the use of two different compression ratios basically functional in a pre-combustion chamber and a main combustion chamber Advantages over Constructions with only one combustion chamber and / or one uniform Compression ratio. The disadvantage, however, is that the fuel, at least in sections comes into contact with a cylinder or duct wall. Thus, the per se sought high turbulence impaired, so that disadvantages in terms of Mixture formation and pollutant emission result.

Therefore, there is still a need for development despite the variety of already known technical solutions. This applies in particular to diesel engines with direct injection, which represent the optimum achievable today with regard to performance, economy and pollutant emission of the internal combustion engines used for passenger cars. By means of a mechanical high-pressure injection of diesel fuel, it is possible to realize very high pressures which cause an extremely fine atomization with rapid reprocessing of a combustible mixture. Furthermore, a homogenization of the mixture can be achieved, at least in part, similar to a gasoline engine to largely avoid soot formation by early injection with low formation of nitrogen oxides. Nevertheless, there is room for improvement to avoid costly post combustion systems such as soot filters or to refrain from such.

task The invention is a reciprocating internal combustion engine with prechamber and main combustion chamber in such a way that a largely homogeneous Treatment of fuel and air as an essential prerequisite for one Low-emission combustion is achieved.

These Task is solved by concentrating the piston as a stepped piston with one at the piston bottom arranged circular Stage is designed and by in the upper cylinder area in the As a main combustion chamber trained space an injector centrally is arranged, wherein the fuel is injected such that from the injection nozzle emerging fuel jets and emerging from the overflow air jets nearly collide head-on. This will give a good atomization of the Fuel reaches, a good mixing with the air and a low-emission combustion without wall contact.

alternative It is suggested that the piston be a nasal piston with around the circumference the piston crown in pairs opposite arranged noses is designed and that in the area of each nose in the upper cylinder area in each case a trained as antechamber Room arranged with an injection nozzle is, wherein the fuel is injected so that the already burning fuel jets from the respective opposite overflow in the As a main combustion chamber trained space obliquely meet. Thus meet the burning fuel jets to form feinballiger turbulence on top of each other and create a fireball that in one without wall contact by the shape of piston and cylinder head defined combustion chamber burns.

advantageous Embodiments are the subject of the dependent claims, whose Features and effects in the embodiment described in more detail become.

With the embodiment of the invention is an internal combustion engine created, whose operation as a diesel similar Stratified charge motor can be characterized with which a far-reaching Homogenization of for the combustion of necessary mixture is feasible. It will by using different compression ratios in an antechamber and a main burn room as well as with these Subassemblies connecting overflow channels a allows very high turbulence in the combustion chamber, which compared to the The prior art causes improved fuel treatment. Here is another advantage that this combustion takes place without wall contact, so that low pollutant emissions (HC, CO and soot) at Operation in this regard Internal combustion engine ensured can be. Consequently, the present technical solution is also from the aspect increasingly stringent emissions legislation.

One embodiment The invention is illustrated in the drawing and will be described below described. Show it:

1 the basic structure of a version with stepped piston in a sectional view

2 a detail of the embodiment according to 1 in perspective view

3 the basic structure of a design with a nose piston in a sectional view

4 a detail of the embodiment according to 3 in perspective view

In the drawing, the assemblies of an internal combustion engine are shown in reciprocating design, which are relevant in the present situation. The internal combustion engine has a cylinder, which includes a cylinder shell 1 and a cylinder head 2 consists. Within the cylinder, a piston is arranged, which is designed at its piston crown with projections.

This piston can according to 1 and 2 as a stepped piston 3 be configured, the piston at the bottom of a concentrically arranged circular stage 4 having.

Likewise, this piston according to 3 and 4 as a nasal piston 5 be configured, on the circumference of the piston crown in pairs oppositely arranged lugs 6 having.

The circular step 4 of the stepped piston 3 or the noses 6 of the nose plunger 5 each stand in the cylinder head 2 designed contours in operative connection that in the upper cylinder area due to the movement of the stepped piston 3 or nasal piston 5 between the piston 3 respectively. 5 and the cylinder has two spaces 7 and 8th can be formed. The space 7 is as antechamber and the room 8th is designed as a main burning room. These rooms 7 and 8th have different volumes, resulting in different compression ratios during operation of the internal combustion engine.

The rooms 7 and 8th are through overflow channels 9 connected to each other in the cylinder head 2 are arranged radially and / or axially. These overflow channels 9 allow a flow through the highly compressed air or the burning fuel jets 11 from the room designed as antechamber 7 in the room designed as a main burning room 8th , Consequently, towards the end of the compression stroke by the movement of the piston 3 respectively. 5 in the direction of the cylinder head 2 from the space formed as a prechamber with higher pressure 7 Air through the overflow channels 9 in the space designed as a main combustion chamber with lower pressure 8th pressed.

In the execution according to 1 and 2 with a stepped piston 3 is in the upper cylinder area and inside of the cylinder head 2 in the room designed as a main burning room 8th an injection nozzle 10 centrally located. As injector 10 Preferably, a multi-hole nozzle is used, wherein the number of nozzle openings of the number of cylinder head 2 arranged overflow channels 9 equivalent.

In the room designed as antechamber 7 is during the immersion of the stepped piston 3 in the corresponding recesses of the cylinder head 2 a part of the combustion air is compressed so that when overflow through the overflow 9 in the room designed as a main burning room 8th Blasting high exit velocities form in the from the injection nozzle 10 ignitable fuel is injected. The fuel is thus injected in such a way that from the injection nozzle 10 emerging fuel jets 11 and those from the overflow channels 9 exiting air jets 12 almost collide head-on. This operating point is off 1 can be seen, as a result of which the fuel passes without wall contact for combustion.

In the execution according to 3 and 4 with a nose plunger 5 is in the area of every nose 6 in the upper cylinder area in each case a trained as antechamber space 7 with an injection nozzle 10 arranged. Preferably, the number of noses formed on the piston crown corresponds 6 the number of cylinders in the cylinder head 2 designed overflow channels 9 and the number of associated injectors 10 , The fuel is injected in such a way that the already burning fuel jets 11 from the opposite overflow channels 9 in the room designed as a main burning room 8th meet each other at an angle. This operating point is off 3 can be seen, as a result of which the fuel passes without wall contact for combustion. Here, the trained as the main combustion chamber space 8th a glow plug 13 assigned, so that a cold start is guaranteed.

According to 1 are the cylinder in the area of the cylinder head 2 an inlet valve 14 and an exhaust valve 15 assigned, so that with this internal combustion engine, a 4-stroke operation is possible.

According to 3 is alternatively provided that the cylinder in the region of the cylinder jacket 1 an inlet slot 16 and an outlet slot 17 are assigned, so that with this internal combustion engine, a 2-stroke operation is possible.

In a further embodiment, it is possible that the space formed as antechamber 7 instead of air an air-residual gas mixture is assigned. This can be over the trained in the main combustion chamber space 8th be compacted present pressure. For this purpose inlet valve 14 and exhaust valve 15 Controlled so that burned exhaust gas can be retained in the cylinder, which after mixing with the sucked air proportionate in the space formed as antechamber 7 arrives. It is possible that only the proportion of near-wall exhaust gas is ejected, which corresponds to the air charge. Thus, flow losses are avoided.

For the injection system with the injector 10 For example, a pump-nozzle unit, a common-rail system, a combination of these two systems (eg, a pressure-boosted common-rail system), or another known injection system (eg, distributor injection pump) may be used.

The room designed as a main burning room 8th should take into account the shape of stepped piston adapted to the forming beam shapes 3 or nose pistons 5 as well as cylinder head 2 be designed so that even at full load combustion takes place without wall contact.

Furthermore, the compression ratio in the space formed as the main combustion chamber 8th to choose so that in each operating state of the internal combustion engine, a reliable auto-ignition is achieved. Furthermore, when using a nasal piston 5 the separate noses 6 be joined together to form a common structure in the form of a circular ring or the like.

Then instead of several injectors 10 only a single such assembly needed and realized the combustion at a common location as a fireball.

Finally, as fuel even those with poor auto-ignition behavior can be injected, such as alcohols with low cetane number, because depending on the structural design either by the high turbulence and thus good atomization and mixing or by the high pressures and temperatures significantly improve the ignition behavior.

1

cylinder surface

2

cylinder head

3

stepped piston

4

circular step

5

nose piston

6

nose

7

Room / antechamber

8th

Room / main combustion chamber

9

overflow

10

injection

11

Fuel jet

12

air jet

13

glow plug

14

intake valve

15

outlet valve

16

inlet slot

17

exhaust port

Claims (12)

Internal combustion engine in reciprocating design with at least one disposed within a cylinder piston which is configured on its piston head with projections which are operatively connected to contours configured in the cylinder head such that two spaces can be formed in the upper cylinder region as a result of the movement of the piston between the piston and the cylinder are, these spaces each having a different compression ratio and are connected by overflow such that at the end of the compression stroke air is forced from the pre-chamber with a higher pressure formed a space through the transfer channels in the designed as a main combustion chamber with lower pressure other space characterized in that the piston as a stepped piston ( 3 ) with a concentric arranged on the piston head circular step ( 4 ) and that in the upper cylinder area in the space formed as the main combustion chamber ( 8th ) an injection nozzle ( 10 ) is centrally arranged, wherein the fuel is injected in such a way that from the injection nozzle ( 10 ) emerging fuel jets ( 11 ) and from the overflow channels ( 9 ) exiting air jets ( 12 ) almost collide head-on. Internal combustion engine according to claim 1, characterized in that in the space formed as antechamber ( 7 ) during the immersion of the stepped piston ( 3 ) in the corresponding recesses of the cylinder head ( 2 ) a portion of the combustion air is compressed so that when overflow through the transfer channels ( 9 ) in the room designed as a main burning room ( 8th ) Jets of high outflow velocities into which the injection nozzle ( 10 ) ignitable fuel is injected, which passes without wall contact for combustion. Internal combustion engine according to claim 2, characterized in that the injection nozzle ( 10 ) is a multi-hole nozzle, wherein the number of nozzle openings of this multi-hole nozzle of the number of cylinder head ( 2 ) arranged overflow channels ( 9 ) corresponds. Internal combustion engine in reciprocating design with at least one disposed within a cylinder piston which is configured on its piston head with projections which are operatively connected to contours configured in the cylinder head such that two spaces can be formed in the upper cylinder region as a result of the movement of the piston between the piston and the cylinder are, these spaces each having a different compression ratio and are connected by overflow such that at the end of the compression stroke air is forced from the pre-chamber with a higher pressure formed a space through the transfer channels in the designed as a main combustion chamber with lower pressure other space characterized in that the piston is designed as a nasal piston ( 5 ) with on the circumference of the piston crown in pairs opposite arranged lugs ( 6 ) and that in the area of each nose ( 6 ) in the upper cylinder area in each case a trained as antechamber space ( 7 ) with an injection nozzle ( 10 ), wherein the fuel is injected in such a way that the already burning fuel jets ( 11 ) from the respectively opposite overflow channels ( 9 ) in the room designed as a main burning room ( 8th ) meet at an angle. Internal combustion engine according to claim 4, characterized in that the number of lugs formed on the piston head ( 6 ) the number of cylinders in the cylinder head ( 2 ) overflow channels ( 9 ) and the number of associated injectors ( 10 ) corresponds. Internal combustion engine according to claim 1 or 4, characterized in that in the cylinder head ( 2 ) radially and / or axially arranged overflow channels ( 9 ) passing through the highly compressed air ( 12 ) or the burning fuel jets ( 11 ) from the space formed as antechamber ( 7 ) in the room designed as a main burning room ( 8th ) enable. Internal combustion engine according to claim 1 or 4, characterized in that the space formed as the main combustion chamber ( 8th ) a glow plug ( 13 ) assigned. Internal combustion engine according to claim 1 or 4, characterized in that the cylinder head ( 2 ) Inlet valves ( 14 ) and exhaust valves ( 16 ) assigned. Internal combustion engine according to claim 1 or 4, characterized in that the cylinder jacket ( 1 ) Inlet slots ( 16 ) and outlet slots ( 17 ) assigned. Internal combustion engine according to claim 1 or 4, characterized in that the space formed as antechamber ( 7 ) is assigned an air-residual gas mixture instead of pure air. Internal combustion engine according to claim 10, characterized that only the proportion of near-wall exhaust gas is ejected, which of the air filling equivalent. Internal combustion engine according to claim 1 or 4, characterized characterized in that the injection system is a pump-nozzle unit or a common rail system or a combination of these systems or another injection system known per se.