EP2150706B1 - Gas-dynamic pressure wave machine - Google Patents

Description

The invention relates to a gas-dynamic pressure wave machine for charging an internal combustion engine according to the features in the preamble of patent claim 1.

Internal combustion engines for motor vehicles are charged to increase their efficiency, i. the degree of filling is improved. Charged engines have a smaller capacity and lower specific consumption than naturally aspirated engines of the same power.

Charging systems that generate gas-dynamic processes in closed gas channels and use them for charging are generally referred to as pressure wave superchargers or pressure wave machines. Usually, the cell rotors used in pressure wave machines are made of cast material. The cell rotors are cylindrical and usually have axially straight, cross-section constant running channels extending from the hot gas to the cold gas side. It is known to actively drive the rotor in pressure wave chargers, which are used as charge air compressors for internal combustion engines. By the EP 0 235 609 A1 However, also counts a driven by the gas forces, freewheeling Pressure wave loader to the prior art. The cell rotor has axially parallel or obliquely to the rotor axis or helically wound cell separation walls. The drive of the cell rotor is effected by the action of the cell walls by high-pressure exhaust gases, which open in the rotor housing via gas channels in a corresponding loading angle and set by the entry of the exhaust gas, the cell rotor in rotation.

From the DD 285 397 A5 is a gas-dynamic pressure wave machine with non-constant cell cross-section known. Due to the changing cross-section, the most important gas-dynamic parameters are to be improved compared to those of cylindrical rotors. A change in the radial cell height with the rotor length x by the amount 2ax ^b with a = 0.03 to 0.1 and b = 1.5 to 2.5 to provide improved results.

From the DE 690 08 541 T2 is known a pressure exchanger with a frusto-conical rotor. The radial height of the individual rotor cells varies in the longitudinal direction of the rotor. In the EP 0 431 433 A1 a pressure exchanger for an internal combustion engine is shown, wherein the pressure exchanger should have an increased flushing energy. The individual cells of the cell rotor should generally have a constant cross section along their longitudinal axes, which only succeeds due to the inclination of the cells with respect to the longitudinal axis of the rotor in that the cell height decreases.

Aerodynamic pressure wave machines also count by the DE 1 428 029 B to the prior art, in which cylindrical rotors are used. The individual cells may be connected to a shroud and a hub mechanically, by welding or by soldering. Also, the production of cells from box sections or a meander-like curved band is possible. From the GB 1 058 577 A It is known to provide several concentric cell rings. There are also different approaches to cell geometry. In the GB 920 624 A it is proposed that Build cell dividing walls from Z-shaped bent sheets. The individual cells can also be configured honeycomb, as in the GB 840 408 A is shown. If the cells are arranged in several concentric rings, it is according to the teaching of GB 920 908 possible to provide cell cross-sections that differ from ring to ring.

To improve the catalytic effects of the exhaust gases in supercharged by means of pressure wave engines combustion engines is in the EP 0 143 956 A1 proposed to coat the cells of the cell wheel with a catalyst material.

The problem with today's systems is the thermal load collective, which is subject to the entire component geometry of the cell rotor. Temperatures of up to 1,100 ° C can be found on the hot gas side of the cell rotor and temperatures of up to 200 ° C on the cold gas side. A thermally induced component distortion and a resulting sub-optimal efficiency are the result. Problems occur in particular in the gap dimensional accuracy between the gas-conducting elements.

In the regularly axially straight running gas channels, the gas inlet angle are not optimal. Cast cell rotors also have a high moment of inertia, due to relatively large wall thicknesses. In addition, the casting technology production of fine cell structures is very expensive. Cast manufacturing also requires relatively expensive inspection procedures and high reject rates.

Due to the manufacturing difficulties and taking into account the requirement profiles of pressure wave superchargers, the economic production of a cell rotor taking into account all requirements on an industrial scale is very problematic.

On this basis, the invention is based on the object, a gas-dynamic pressure wave machine for charging an internal combustion engine, in particular with regard to the design of the Cell rotor to optimize in terms of manufacturing technology and to increase the efficiency of the pressure wave machine.

This object is achieved with a gas-dynamic pressure wave machine having the features of patent claim 1.

Advantageous developments of the inventive concept are the subject of the dependent claims.

The essence of the invention can be seen in the fact that the outer circumference of the cell rotor increases from its exhaust side to its charge air side. This, in effect, non-cylindrical design of the cell rotor brings with it the possibility of being built, i. non-cast, cell rotors with high manufacturing accuracy cost-effectively. The reason is that the individual cell dividing walls between adjacent cells, while maintaining close dimensional tolerances, in particular while maintaining close joining gaps, with the jacket elements radially limiting the cells inside and outside, i. on the outside with an outer sheath and the inside with an inner sheath, can be connected. Due to the non-cylindrical outer contour of the cell rotor, a previously manufactured outer sheath can be slipped over the individual cell dividing walls, so that the joint gap becomes minimal due to displacement of the outer sheath or of the inner sheath in the longitudinal extent of the cell rotor, which results in cost-effective, reliable and very precise joining the individual components, in particular by soldering or fusion welding processes enabled. The jacket elements of the cell rotor can therefore be made somewhat longer than the individual cell dividing walls in order to ensure by Relatiwerlagerung in the direction of the common longitudinal axis that the joint gap is as small as possible.

The non-cylindrical outer contour of the cell rotor also allows self-centering of the jacket elements during the joining process. On the other hand, if you wanted to build cylindrical cell rotors, you had to work much tighter Tolerance ranges are met in order to realize circumferentially consistently small joining gaps can.

The cell rotor is preferably formed frusto-conical. This information refers to its external geometry. The shape of the outer geometry also determines the internal geometry of the cell rotor, since the height of a cell measured in the radial direction should remain constant over the longitudinal extent of the cell rotor. Nevertheless, the cross-sectional area of the individual cells increases from the exhaust side to the charge air side because the annular area of a cell ring from the charge air side to the exhaust side also increases, but the number of cells remains constant. Increasing the cross-sectional area toward the exhaust side results in a reduction in the velocity of the combustion gas within a cell and thus in a pressure increase, which can increase the efficiency and charge level achieved by the pressure wave machine.

The advantages of the invention are not only in frustoconical cell rotors to bear, but also when the outer jacket of the cell rotor is curved in the longitudinal extension of the cell rotor and, accordingly, all cells are curved in their longitudinal extent, in the sense that they are on the cold gas side at a greater distance to the axis of rotation of the cell rotor run as on the acted upon by exhaust gas hot gas side. The curvature may be constant over the length of the cell rotor. Preferably, the curvature of the outer shell increases from the exhaust side to the charge air side. The lateral surface can therefore be parabolically curved in the longitudinal extent of the cell rotor or form a parabolic rotational body. Theoretically, it is also possible to line straight or curved curve sections, ie those with constant and variable pitch, with the result that the outer circumference of the cell rotor increases from its exhaust side to its charge air side. In any case, however, the height of the cells should remain constant.

In practical implementation, the angle between the axis of rotation or longitudinal axis of the cell rotor and its outer jacket can be up to 50 °. The angle may vary depending on the curvature or slope of the outer shell. The angle is preferably greater than 20 °.

The cell rotor can be assembled from semi-finished products of different materials. This means that, in particular, metallic materials, in particular steels of different chemical composition with different mechanical properties, can be used. For example, the individual cells can be formed from thin sheet metal elements. Hereby, the gas guide grid formed of the cell dividing walls can be made of bent, thin sheet metal elements and connected to the outer and inner supporting structural elements, i. an outer sheath and an inner sheath to be connected. The finely structured cell dividing walls are preferably made of a thin stainless steel foil with wall thicknesses that can be in a range of 0.05 - 1.0 mm.

The jacket may be formed from a conical expansion of a cylindrical tubular component, i. by cold forming. The selection of materials suitable for the requirements enables a reduction of the mass and in relation to cast components a significant reduction of the mass moment of inertia. At the same time, the obstruction and blind surfaces resulting from the individual cell dividing walls can be reduced as much as possible, with an optimum being sought between as many cells as possible and the smallest possible blind surface or obstructive surface. The optimal ratio of the cross-sectional areas of the cells to the cross-sectional area of the individual cell dividing walls is essentially material-dependent, since the individual cell dividing walls are subject to strong mechanical and thermal stresses.

Since semifinished products with very small wall thickness are used for the cell dividing walls, the design of the cell rotor according to the invention is closed on the periphery. Depending on the size of the rotor can be 1 to 3 concentric cell rings, which are separated by concentric shell elements, provided. In the case of several cell rings, the jacket element separating the cell rings is at the same time the outer jacket for the inner cell ring and the inner jacket for the outer cell ring.

Another essential aspect of the invention is the reduced noise development of the pressure wave machine. A cell rotor usually has equal cell cross-sections over its entire circumference. However, there is the danger that, in conjunction with internal combustion engines, standing waves within the cell rotor and thereby noise generation due to resonance vibrations occur. In the cell rotor according to the invention, it is possible to build pressure wave machines tuned to the respective internal combustion engine by arranging irregularly distributed cells over the circumference of the cell rotor in the circumferential extent. In other words, the noise development can be extremely limited or even prevented by varying the distances between the individual cell dividing walls. By varying the distances, the sound pressure wave from the exhaust tract of the internal combustion engine can be chopped up by the plurality of individual cells, so that the outlet side of the cell a uniform exit gas flow is formed, which has only small pressure fluctuations and thus minimal acoustic emissions. The particular advantage over cell rotors produced by casting technology is that, by changing the position of individual cell dividing walls, resonant vibrations can be easily or at the same time inexpensively restricted or prevented.

With regard to the distribution of the cells over the circumference, an irregular sequence of cells of different widths or different circumferential extents is provided. In the simplest case, two cells of different widths are uneven, that is, distributed as irregularly as possible over the circumference of the cell rotor Repetitions and thus the possibility to be stimulated to resonant vibrations to avoid. The irregular distribution of the cells over the circumference refers not only to a single cell ring, but to the cells of all cell rings. In this case, it may be favorable if the relative deviations in the circumferential extent between the cells of each cell ring are the same. If the cells of a cell ring extend, for example, in one above 2 ° and in the other case above 3.5 °, then this ratio also applies to the cells of other cell rings. Preferably, the cells in cross-section are circular ring pieces.

In the cell rotor according to the invention balancing rings may be provided, which are preferably mounted on both ends of the cell wheel. The balancing rings serve on the one hand to support the filigree cell system and also fulfill a sealing function to the adjacent exhaust pipes or charge air ducts. About the balancing rings an additional fixing of the outer jacket is possible. The balancing rings also serve to compensate for uneven mass distributions.

Furthermore, it is considered advantageous if the surface of the cell dividing walls is specifically roughened to minimize the gas friction on the cell dividing walls. This roughened surface structure leads to a fluidic boundary layer minimization and to an improvement of the flow conditions within the individual cells. Also, this feature of the roughened surface structure can be relatively easily and inexpensively realized in built cell wheels in contrast to casting solutions.

Furthermore, it is possible to provide the cell partitions at least partially with a catalytic coating which already causes additional exhaust gas purification processes during the charging of the exhaust gas.

The cell rotor according to the invention can rotate with respect to the inlet angle of the gas flow through obliquely to the direction of rotation cell walls be offset. The cell walls can be parallel to the axis or oblique to the rotor axis.

Another advantage of the pressure wave machine according to the invention is that with the same length of the gas channels or the individual cells, the overall length of the cell rotor can be shortened overall. This effect is all the more pronounced, the greater the angle between the central longitudinal axis of the cell rotor and the outer jacket.

The very decisive advantage of the invention can be seen in the improved manufacturability of the cell rotor. The materially and / or positively connected to the outer shell or the inner jacket cell walls can be added inexpensively with high precision. For example, the cell system can be mechanically connected to the adjacent jacket elements. As particularly favorable brazing processes are considered. Possible dimensional differences can be largely reduced by non-cylindrical design, in particular by conicity of the components. In addition, a Nachjustierbarkeit due to the self-centering of individual components of the pressure waves of the cell rotor is possible, as well as process changes in the production of the cell rotor and geometry changes are flexible and possible in less time.

The supporting inner system of the cell rotor can be made by machining. This is a shaft with corresponding storage means, on which corresponding sealing means are provided.

In principle, manufacturing processes such as bending, deep-drawing or hydroforming can be used for the production of the individual components of the cell rotor, wherein the choice of the manufacturing process depends essentially on the component geometry. In this case, there are many possibilities, especially in the formation of the cells. It is considered to be particularly favorable when the cell dividing walls are alternately connected to one another in the region of the outer jacket and in the region of the inner jacket, and components of one in the circumferential direction of the cell rotor extending, meandering shaped cell plate are. Such a cell plate is brought in the assembly due to the small wall thicknesses in the desired non-cylindrical shape, in particular a cone shape, and joined with the outer shell and the inner shell.

Alternatively, it is also possible to install individual cell dividing walls, in particular those which are Z-shaped in cross section. The respective upper and lower legs of a Z-shaped cell dividing wall serve to join the outer casing or the inner casing.

Also, double Z-shaped configured cell walls are conceivable, the middle cross section of such configured cell walls so to speak forms a sheath which extends between the radially outer and radially inner region of the cell walls or cells and thus effectively forms a separation jacket.

In principle, it is also possible for the cell dividing walls to be part of cell elements profiled in a U-shaped cross-section, i. are generally part of open hollow sections. Alternatively, it is also conceivable that the cell dividing walls are part of thin-walled, closed hollow profiles. For example, a number of square profiles could be spaced apart around the circumference. By varying the distances between the individual square profiles, the desired variation of the cross sections of the individual cells results.

Figur 1

einen Längsschnitt durch einen Rotor einer Druckwellenmaschine und

Figuren 2 und 3

in der Stirnansicht und in der Seitenansicht eine schematische Darstellung eines Zellenrotors.

The invention will be explained in more detail with reference to a dargestellen in the drawings, schematic embodiment. It shows:

FIG. 1

a longitudinal section through a rotor of a pressure wave machine and

FIGS. 2 and 3

in the end view and in side view a schematic representation of a cell rotor.

FIG. 1 shows a cell rotor 1, which forms the Kembestandteil a gas-dynamic pressure wave machine for charging an internal combustion engine. The cell rotor 1 is rotatably mounted in a manner not shown in a housing about its longitudinal axis LA. It is located between a charge air supply line and a combustion gas exhaust line. The arrow A indicates the inflow direction of charge air. The air taken up inside the cell rotor 1 is compressed by inflowing exhaust gases flowing into the cell rotor 1 from the opposite side in the direction of the arrow B. The compressed intake air is expelled in the direction of the arrow C. The exhaust gas exits in the direction of the arrow D from the cell rotor 1.

Essential in the cell rotor according to the invention is its non-cylindrical structure. The cell rotor 1 has a peripherally closed outer shell 2, which is formed in this embodiment, cone-shaped. As a result, the cell rotor as a whole has the shape of a truncated cone. The outer periphery of the cell rotor increases from its exhaust side 3 to its charge air side 4 towards. The cell rotor is mounted on a shaft 5, which may be coupled in a manner not shown with drive means. The shaft 5 carries a frusto-conical hub 6, to which a cell structure of the cell rotor 1 is attached. The gas-permeable areas of the cell rotor 1 are divided into two concentric cell rings 7, 8. The cell rings 7, 8 are each closed in the radial direction, so that a gas exchange can take place only in the longitudinal orientation of the cell rotor 1. The height of the individual cells measured in the radial direction is constant. That is, the outer jacket 2 is parallel to an inner jacket 9 of the outer cell ring. With regard to the inner cell ring, this inner casing 9 is to be regarded as the outer casing 9 'which, together with a further radially inner inner casing 10 radially inner cell ring 8 limited in the radial direction. The jacket elements 2, 9, 10 are concentric with one another.

Based on FIG. 2 It can be seen that the cell rotor 1 has a plurality of cells 11, 12, 13, 14. Between the individual cells 11-14 are cell dividing walls 15, which are formed from sheet metal elements. The cell dividing walls 11-15 are preferably materially connected by soldering or fusion welding to the respective inner shell 9, 10 or the respective outer shell 2, 9 '.

In each cell ring 7, 8 there are two cells of different circumferential extent. The respective cell types 11, 12; 13, 14 are preferably arranged distributed regularly over the circumference of the cell rotor 1.

In the side view of FIG. 3 in addition, the angle W is drawn, which is measured between the outer shell 2 and the longitudinal axis LA of the cell rotor 1 and a maximum of 50 °.

Reference numerals:

1 -

cell rotor

2 -

outer sheath

3 -

exhaust side

4 -

Charge air side

5 -

wave

6 -

hub

7 -

cell ring

8th -

cell ring

9 -

inner sheath

9 '-

outer sheath

10 -

inner sheath

11 -

cell

12 -

cell

13 -

cell

14 -

cell

15 -

cell wall

LA -

longitudinal axis

A -

arrow

B -

arrow

C -

arrow

D -

arrow

W -

angle

Claims (19)

1. Gas-dynamic pressure wave machine for charging an internal combustion engine, comprising a cell rotor (1) which is rotatably mounted in a housing and is arranged between a feed line for charge air and an exhaust gas line for combustion gases, wherein the outer periphery of the cell rotor (1) increases from the exhaust gas side (3) thereof to the charge air side (4) thereof, characterised in that a height of a cell of the cell rotor (1) measured in the radial direction remains constant over the longitudinal extent of the cell rotor (1), wherein the cross-sectional area of the individual cells increases from the exhaust gas side to the charge air side.
2. Pressure wave machine according to claim 1, characterised in that the cell rotor (1) has a truncated conical form.
3. Pressure wave machine according to claim 1, characterised in that an outer casing (2) of the cell rotor (1) is curved in the longitudinal extent of the cell rotor (1).
4. Pressure wave machine according to claim 3, characterised in that the curvature of the outer casing (2) increases from the exhaust gas side (3) to the charge air side (4).
5. Pressure wave machine according to claim 4, characterised in that the outer casing (2) is parabolically curved in the longitudinal extent of the cell rotor (1).
6. Pressure wave machine according to one of the claims 1 to 5, characterised in that the cell rotor (1) is assembled from semi-finished products made from different materials.
7. Pressure wave machine according to one of the claims 1 to 6, characterised in that the cell rotor (1) has cell partition walls (15) extending from the exhaust gas side (3) thereof to the charge air side (4) thereof, wherein the cell partition walls (15) are made from sheet metal elements which are connected to an inner casing (9, 10) and an outer casing (2, 9').
8. Pressure wave machine according to claim 7, characterised in that the cell partition walls (15) have a thickness in the range of 0.05 mm to 1.0 mm.
9. Pressure wave machine according to claim 7 or 8, characterised in that the cell partition walls (15) are connected to the inner casing (9, 10) and/or the outer casing (2, 9') in bonded manner by soldering or welding.
10. Pressure wave machine according to one of the claims 7 to 9, characterised in that the central partition walls (15) are connected to the inner casing (9, 10) and/or the outer casing (2, 9') in form-fitting manner.
11. Pressure wave machine according to one of the claims 7 to 10, characterised in that the cell partition walls (15) are connected to one another alternately in the region of the outer casing (2, 9') thereof and in the region of the inner casing (9, 10) thereof and are components of a cell metal sheet which is configured meandering and extends in the peripheral direction of the cell rotor (1).
12. Pressure wave machine according to one of the claims 7 to 10, characterised in that the cell partition walls (15) are configured double-Z-shaped in cross-section.
13. Pressure wave machine according to one of the claims 1 to 12, characterised in that between 1 and 3 concentric cell rings (7, 8) are provided, wherein adjacent cell rings (7, 8) are separated from one another by a concentric casing element (9, 9').
14. Pressure wave machine according to one of the claims 1 to 13, characterised in that cells (11-14) which deviate from one another in the peripheral extent are irregularly distributed over the periphery of the cell rotor (1).
15. Pressure wave machine according to claim 13 or 14, characterised in that the relative deviations in the peripheral extent between the cells (11-14) of each cell ring (7, 8) are the same.
16. Pressure wave machine according to one of the claims 1 to 15, characterised in that the cells (11-14) are segments of circular rings in cross-section.
17. Pressure wave machine according to one of the claims 1 to 16, characterised in that at least one balancing ring is arranged on the outer periphery of the cell rotor (1).
18. Pressure wave machine according to one of the claims 7 to 17, characterised in that the cell partition walls (15) have an at least partially roughened surface structure.
19. Pressure wave machine according to one of the claims 7 to 18, characterised in that the cell partition walls (15) are provided at least partially with a catalytic coating.

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