DE8419349U1 - MIXERS FOR MIXING AIR AND COMBUSTION GAS, EXAMPLE FOR COMBUSTION ENGINES - Google Patents

Description

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χ!,;. RAU & SCHNECK

PATENT LAWYERS

DIPL.-ING. DR. MANFRED RAU DIPL-PHYS. DR. HERBERT SCHNECK APPROVED REPRESENTATIVE AT THE EUROPEAN PATENT OFFICE

VNR Io6984 Nuremberg, June 27th, 1984

R / St

Motoren-Werke Mannheim Aktiengesellschaft "orm. Benz Stationary Engine Construction Department, Carl-Benz-Straße 5,

6800 Mannheim 1

Mixer for mixing air and fuel gas, e.g. for internal combustion engines

The invention relates to a mixer according to the preamble of claim 1.

Such mixers working on the Venturi principle for mixing air and fuel gas are known and customary. The air is supplied to them coaxially. The gas enters through an annular slot-shaped gas inlet supplied in the area of the narrowest cross-section of the Venturi tube. The mixture of air and gas begins in the narrowest cross-section and then continues in the diffuser. By analyzing exhaust gas compositions found that the air-fuel-gas mixture is imperfect.

Try different additional mixing devices, that were arranged downstream of the Venturi tube did not bring satisfactory mixing success and / or led to an inadmissibly high pressure loss.

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The invention is therefore based on the object of providing a | i

To further develop mixers of the quality standard in such a way that |

that an improvement in the mixture of air and fuel gas |;

achieved without significant additional pressure losses *

will.

I ι This object is achieved according to the invention by the features j

of the characterizing part of claim 1 solved. ι

Characterized that the air is forced to a swirling motion prior to entering the venturi \, the air gets a higher resulting speed. This twist- {'*>

component is in the area of the narrowest cross-section 1

of the Venturi tube is reinforced, resulting in an ig

Reinforcement of the turbulence and thus a reinforcement |

the mixing of gas and air results. Furthermore |

v / ird by the centrifugal effect of the swirl movement j

the air more in the wall area of the diffuser

printed where in the boundary layer area to an increased extent]

the gas flows. This improves the mixing. Still takes place due to the swirl component of the flow a separation of the flow in the diffuser only in a further downstream located area, i.e. the pressure loss in the diffuser

are reduced. ;

The design of the swirl grille as an axial grille §

is particularly simple in construction. In particular, 1

the measures according to the invention particularly space-saving f

and little effort. It needs the swirl grille f

only upstream of a standard mixer |

to become. f

I ι

Further details and advantages of the invention result from f from the following description of an embodiment | example based on the drawing. It shows |

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1.

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1 shows a cross section through a mixer according to of the invention and

FIG. 2 shows a development of a cross section according to FIG Section line Ii-II in FIG. 1.

The mixer shown in Fig. 1 has a tubular air inlet 1, the one on the other side and a mixture outlet 2 is assigned coaxially to this is. In an inlet chamber 3 arranged downstream of the air inlet 1, there is an axial grille 4 Swirl lattice arranged. Corresponding to the cylindrical cross section of the inlet chamber 3, this has an axial grid 4 has an annular cylindrical retaining ring 5 on which extends radially to the axis 6 of the mixer Guide vanes 7 are attached. These guide vanes 7 are - as can be seen from FIG. 2 for The direction of flow 8 of the air in the inlet chamber 3 is curved. The one through the entry chamber 3 air flowing in the axial direction receives a swirl component from the axial grille 4; the air leaves the axial grille 4 as an axial swirl flow.

A mixing device in the manner of a Venturi tube 9 is arranged downstream of the axial grille 4. In that area The narrowest cross-section is an annular channel Io from which a slot-shaped gas inlet 11 into the VenturiT tube 9; joins. From this slit-shaped The gas inlet in the circumferential area of the narrowest cross section of the Venturi tube 9 extends in the direction of flow of the gas or gases whose diffuser 12 widens conically towards the mixture outlet. In the Venturi tube 9

isö coaxial a half way up to the narrowest cross section ^ - oval-shaped widening and slightly in the diffuser tapering displacement body 13 arranged »

The air emerges from the axial grille 4 with a strong twisting motion into the Venturi tube 9, with im Area of its narrowest cross section through the annular slot-shaped gas inlet 11 that with the air mixing combustion gas enters. Due to the swirl component, the air has compared to a pure one Axial flow in the area of the gas inlet has a higher speed with a correspondingly higher turbulence, whereby a more intimate mixing of the two gases is achieved. At least the swirl flow remains to a considerable extent also preserved in the diffuser 12, whereby the diffuser flow only later to detach tends to be a swirl-free diffuser flow. This reduces the pressure losses compared to a mixing device reduced in size without swirl grille. Due to the swirl maintained in the diffuser, the penetrates Air also penetrates more intensively into the boundary layer in which the gas flows, which in turn leads to an improvement the mixing effect leads.

In order to keep the pressure losses low in the swirl grille, it is advisable not only to set the guide vanes 7 at an angle to the direction of flow 8 of the incoming air, but also to make them curved, as can be seen from "Fig. 2. ^l '

Claims (2)

DlPL1-ING. DR. MANFRED RAU DIPL.-PHYS. DR. HERBERT SCHNECK APPROVED REPRESENTATIVE AT THE EUROPEAN PATENT OFFICE VNR Io6984 Nuremberg, June 27, 1984 R / St Motoren-Werke Mannheim Aktiengesellschaft vorm. Benz Dept. of stationary engine construction, Carl-Benz-Straße 5, 6800 Mannheim 1 claims 1. Mixer for mixing air and fuel gas, for example for internal combustion engines, with a Venturi tube, an air inlet upstream of this and a gas inlet approximately in the region of the narrowest cross section of the Venturi tube, characterized in that the Venturi -Pipe (9) is upstream of a swirl grille in the air flow path. 2. Mixer according to claim 1, characterized in that the swirl grille is designed as an axial grille (4). POSTFAcWl 04 k UHGt.tthi 30 JeLEKJN fl? 11/371 At TElEX 04/23 945 POSTSCHECK NBG, 1643 52 <