EP3128233A1 - Mixing arrangement comprising evaporator - Google Patents

Abstract

A mixed arrangement (10) for mixing fuel vapor with air, preferably for a fuel-powered vehicle heater, comprises a fuel vaporisation arrangement (12) for delivering vaporized fuel to a vaporization side (14) of the fuel vaporization assembly (12) and one of the fuel vaporisation arrangement (12) at the vaporization side (14) at least partially oppositely disposed air-fuel mixing unit (26) for mixing of fuel discharged at the Abdampfungsseite (14) with air.

Description

The present invention relates to a mixing arrangement for mixing fuel vapor with air, preferably for a fuel-powered vehicle heater, comprising a fuel vaporisation arrangement for dispensing vaporized fuel on a vaporization side of the fuel vaporization assembly.

Such mixing arrangements known in the art are generally part of a combustion chamber, such as a fuel-powered vehicle heater. In this case, vaporized fuel is discharged directly into the combustion chamber and mixed with also in the combustion chamber supplied combustion air. In this conventional structure, the air-fuel mixture produced in the combustion chamber is ignited immediately as soon as there is an air-fuel ratio suitable for combustion. However, this means that neither a defined nor a homogeneous air-fuel ratio can be ensured thereby. Since, however, the composition of the exhaust gases emitted by a heater depends on the air-fuel ratio of the combustible air-fuel mixture, consequently, in such a heater also the pollutant content in the emissions can not be controlled.

In view of these disadvantages known from the prior art, it is the object of the present invention to provide a mixing arrangement with which the air-fuel ratio can be set in a defined manner.

According to the invention, this object is achieved by a mixing arrangement for mixing fuel vapor with air, preferably for a fuel-powered vehicle heater, comprising a fuel evaporation arrangement for dispensing evaporated fuel on a Abdampfungsseite the fuel evaporation assembly and one of the fuel evaporation arrangement on the Abdampfungsseite at least partially opposite arranged air-fuel mixing unit for mixing fuel released on the evaporation side with air.

In a mixing arrangement according to the invention, it is first ensured that fuel vapor emitted at the evaporation side of the mixing arrangement at least partially reaches the air-fuel mixing unit and is mixed with air therein. As a result, it is thus possible initially to ensure a defined air / fuel ratio in the air / fuel mixing unit before the air / fuel mixture is supplied to downstream functional areas, such as a combustion chamber. By the defined adjustment of the air-fuel ratio ultimately the composition of the exhaust gases and thus the pollutant content of such a mixing arrangement having heater can be adjusted precisely.

In a further development of the invention it can be provided that the air-fuel mixing unit has at least one inflow region leading into the air-fuel mixing unit for supplying air into the air-fuel mixing unit. In this case, the inflow region can be arranged such that inflowing air flows essentially parallel to the delivery side of the fuel evaporation arrangement. A particularly homogeneous mixing of air and fuel vapor can be ensured, in particular, when the evaporation side has a substantially planar evaporation surface, since then air supplied parallel to the evaporation surface can flow uniformly over the entire evaporation surface and can mix with discharged fuel vapor.

In order to be able to influence both the flow of supplied air and of discharged fuel vapor specifically within the air-fuel mixing unit, the air-fuel mixing unit may have at least one guide element for conducting air and / or fuel vapor. As a result, turbulence in the flow field of supplied air and discharged fuel vapor can also be provided in a targeted manner, as a result of which a homogeneous air-fuel mixture can be produced in the air-fuel mixing unit. A particularly precise flow guidance of supplied air and discharged fuel vapor can be achieved with a plurality of guide elements. This allows for a high degree of turbulence and This ensures a particularly efficient mixing of air and fuel vapor.

If a plurality of guide elements is provided, the construction may be such that the guide elements are arranged around a central area in succession. This makes it possible to direct air through the guide elements from several directions to the central region and thereby provide in the central region for a particularly high degree of turbulence, which ultimately leads to an effective mixing of air with fuel vapor. By appropriate arrangement of the respective guide elements and a rotational flow of the air-fuel mixture can be generated around the central region within the air-fuel mixing unit.

It can be provided that between at least two immediately adjacent guide elements, preferably between all immediately adjacent guide elements, an inflow region is provided. This can be taken care of for an overall compact overall design, since the already existing guide elements can be used to provide the inflow.

In order to be able to introduce fuel vapor discharged at the evaporation side of the fuel evaporation arrangement into the air-fuel mixing unit in a particularly simple manner and / or to be able to easily discharge air-fuel mixture produced in the air-fuel mixing unit from this, it can be provided that the Air-fuel mixing unit is at least partially open to the fuel evaporation arrangement and / or away from the fuel evaporation arrangement. Preferably, the air-fuel mixing unit is open in the central region to the fuel evaporation arrangement and / or away from the fuel evaporation arrangement. This construction allows in particular for a plurality of successively arranged around the central region guide elements with an inflow between adjacent guide elements an air inlet in the radial direction relative to a surface normal of a plan Abdampfungsfläche and a mixture removal from the air-fuel mixing unit substantially in the direction of the surface normal.

In order to be able to achieve a defined flow guidance within the air-fuel mixing arrangement, it can be provided that at least one guide element has at least one straight or / and curved flow deflection surface.

In a further development of the invention it can be provided that at least two guide elements are formed integrally with each other. As a result, during operation, a defined relative positioning of the respective guide elements and thus a defined flow guidance can always be ensured. If at least two guide elements extend as far as the central area of the air-fuel mixing unit, it is preferred if these are formed integrally with one another in the central region. As a result, it can be effectively ensured that air flowing toward the central region and / or flowing fuel vapor is not influenced by any connection points between two guide elements.

In order to be able to selectively supply the air-fuel mixture formed in the air-fuel mixing unit to downstream functional areas, such as a combustion chamber, the mixing arrangement may comprise a mixture guiding arrangement for discharging an air-fuel mixture formed in the air-fuel mixing unit have the air-fuel mixing unit away. The mixture guide assembly may be integral with or separate from the air-fuel mixing unit.

It can be provided that the mixture guiding arrangement is like a shell and at least partially widening away from the evaporation side of the fuel evaporation arrangement. The regional expansion of the mixture guiding arrangement requires, on the one hand, turbulence-generating speed changes of the flowing air-fuel mixture, which in turn results in a further mixing of air and fuel vapor. On the other hand, the density of the air-fuel mixture can be influenced by the regional expansion of the mixture guiding arrangement and adjusted to operating parameters of downstream functional areas, such as a combustion chamber. In addition, the Gemischführungsanordnung here as an adapter between a Exit region of the air-fuel mixing unit and a larger or smaller compared to this inflow of a downstream functional area serve.

However, it should not be ruled out by this that the mixture guiding arrangement can not also have regionally tapered sections. A tapered portion may be provided, for example, in a connection area between the air-fuel mixing unit and the mixture guiding arrangement. Such a portion can contribute to an increase in the flow velocity of the air-fuel mixture emerging from the air-fuel mixing unit and thereby contribute to a further mixing of air and fuel vapor by turbulences. As an alternative to a tapering section in the connection region of the air-fuel mixing unit and the mixture guiding arrangement, a section with a uniform flow cross section may also be provided, for example a cylindrical section.

Depending on the desired flow rate in a direction away from the air-fuel mixing unit direction, the mixture guiding arrangement may be formed with a different shape. Preferably, the mixture guiding arrangement is at least partially conical and / or at least partially convex and / or at least partially concave.

The mixing arrangement may comprise a housing having a bottom wall and a peripheral wall adjoining the bottom wall, wherein the fuel evaporation arrangement is preferably provided on the bottom wall.

In this case, a compact construction can be provided in that a mixture guiding wall of the mixture guiding arrangement is at least partially surrounded by the circumferential wall, wherein an air inflow space is provided between the circumferential wall and the mixture guiding wall. In this embodiment, it can be ensured that, for example, air conveyed by means of a side channel blower flows along the mixture guide wall, so that at low ambient temperatures, the air may be heated before entering the air-fuel mixing unit. In this way, it can be ensured in particular that the evaporation of fuel in the fuel evaporation arrangement is not impaired by cold air flowing along the evaporation side.

A reliable evaporation of fuel, which is also largely independent of the positioning of the mixing arrangement, can be ensured by the fact that the fuel evaporation arrangement comprises a liquid fuel from a fuel supply line receiving and by Kapillarförderwirkung to Abdampfungsseite transporting porous evaporation body.

In order to be able to ensure reliable evaporation, in particular in an operating start phase of the mixing arrangement or of the heating device in which the mixing arrangement is installed, it can be provided that the fuel evaporation arrangement comprises a heating arrangement. This may for example be formed spirally and arranged on a side opposite from the evaporation side of the fuel evaporation arrangement side. A high thermal conductivity between the heating arrangement and the fuel evaporation arrangement can be provided by a material connection between the fuel evaporation arrangement and the heating arrangement.

In a further aspect, the present invention relates to a vehicle heater comprising a mixing arrangement according to the invention.

Figur 1

eine Schnittansicht einer erfindungsgemäßen Mischanordnung,

Figur 2

eine Schnittansicht einer erfindungsgemäßen Mischanordnung mit einer abgewandelten Gemischführungsanordnung,

Figur 3

eine Schnittansicht einer erfindungsgemäßen Mischanordnung mit einer gegenüber den Mischanordnungen der Figuren 1 und 2 abgewandelten Gemischführungsanordnung,

Figur 4

eine Schnittansicht einer erfindungsgemäßen Mischanordnung mit einer gegenüber den Mischanordnungen der Figuren 1 bis 3 abgewandelten Gemischführungsanordnung,

Figur 5

eine Schnittansicht gemäß der in Figur 1 gezeigten Linie V-V,

Figur 6

eine alternative Ausgestaltung des in Figur 5 gezeigten Bereichs der Mischanordnung und

Figur 7

eine weitere alternative Ausgestaltung des in Figur 5 gezeigten Bereichs der Mischanordnung.

The present invention will be explained in more detail by reference to the accompanying figures. It shows:

FIG. 1

a sectional view of a mixing arrangement according to the invention,

FIG. 2

a sectional view of a mixing arrangement according to the invention with a modified mixture guiding arrangement,

FIG. 3

a sectional view of a mixing arrangement according to the invention with a relation to the mixing arrangements of FIGS. 1 and 2 modified mixture guiding arrangement,

FIG. 4

a sectional view of a mixing arrangement according to the invention with a relation to the mixing arrangements of FIGS. 1 to 3 modified mixture guiding arrangement,

FIG. 5

a sectional view according to the in FIG. 1 shown line VV,

FIG. 6

an alternative embodiment of the in FIG. 5 shown area of the mixing arrangement and

FIG. 7

another alternative embodiment of in FIG. 5 shown area of the mixing arrangement.

In FIG. 1 is shown a generally designated by the reference numeral 10 mixing arrangement. The mixing assembly 10 may for example be installed in a fuel-powered vehicle heater and is provided for mixing fuel vapor with air.

The mixing assembly 10 includes a fuel vaporization assembly 12 for delivering vaporized fuel to an exhaust side 14 of the fuel vaporization assembly 12. The vaporization side 14 of the fuel vaporization assembly 12 may be as shown in FIG FIG. 1 shown, a flat Abdampfungsfläche include, the surface normal A in FIG. 1 is shown. The surface normal A defines an axial direction in this exemplary embodiment.

The mixing arrangement 10 may have a housing 16 with a bottom wall 18 and a peripheral wall 20 adjoining the bottom wall 18. The fuel evaporation assembly 12 may be positioned on the bottom wall 18 such that the peripheral wall 20 extends substantially parallel to the surface normal A.

The fuel vaporization assembly 12 may include a liquid fuel from a fuel supply line 22 and conveyed by Kapillarförderwirkung to Abdampfungsseite 14, porous evaporation body 24.

This can provide for a reliable evaporation of fuel, which is also largely independent of the positioning of the mixing assembly 10.

In order to be able to ensure reliable evaporation, in particular in an operating start phase of the mixing arrangement 10 or of a heating device in which the mixing arrangement 10 is installed, the fuel evaporation arrangement 12 can comprise a heating arrangement 13. This may for example be formed spirally and arranged on one of the evaporation side 14 of the fuel evaporation arrangement 12 opposite side. A high thermal conductivity between the heating arrangement 13 and the fuel evaporation arrangement 12 can be provided by a material connection between the fuel evaporation arrangement 12 and the heating arrangement 13.

The mixing arrangement 10 further comprises an air-fuel mixing unit 26, arranged at least partially opposite the evaporation evaporation side 12, for mixing fuel discharged at the evaporation side 14 with air. With such an air-fuel mixing unit 26 can first be provided for a defined air-fuel ratio before the air-fuel mixture downstream functional areas, such as a combustion chamber, not shown in Figure 1, is supplied. Since the composition of the exhaust gases released in the combustion process largely depends on the air-fuel ratio, a defined adjustment of the air-fuel ratio ultimately also the composition of the exhaust gases and thus the pollutant content can be controlled.

As in Fig. 1 1, the mixing assembly 10 may include a mixture guide assembly 28 having a mixture guide wall 30 for discharging an air-fuel mixture formed in the air-fuel mixing unit 26 away from the air-fuel mixing unit 26. The Gemischführungswandung 30 of the mixture guide assembly 28 is partially surrounded by the peripheral wall 20 of the housing 16 of the mixing assembly 10 in the present embodiment. Between peripheral wall 20 and mixture guide wall 30 is a Luftanströmraum 31st provided over which air, for example by means of a side channel blower, not shown, along a direction of flow S promotes the air-fuel mixing unit 26 and this is supplied via an inflow 32. In this embodiment, it can be ensured that at comparatively low ambient temperatures cold air flows along the mixture guide wall 30 of the mixture guiding arrangement 28 and can thus be warmed up before it enters the air-fuel mixing unit 26. In the illustrated embodiment, supplied air flows within the air-fuel mixing unit 26 substantially orthogonal to the surface normal A and thus substantially parallel to the evaporation side 14 of the fuel evaporation arrangement 12. This can be taken care of effective mixing of supplied air with discharged fuel vapor.

In order to be particularly easy to introduce fuel vapor into the air-fuel mixing unit 26 and in order to be able to discharge particularly easily from the air-fuel mixture 26 produced in the air-fuel mixing unit, the air-fuel mixing unit 26, as in Fig. 1 shown to be open to the fuel evaporation assembly 12 and away from it in a central region Z. This configuration thus allows an air supply in the air-fuel mixing unit 26 with respect to the surface normal A radially inward to the central region Z in respective, between immediately adjacent guide elements 34 limited flow channels 33 and a mixture discharge from the air-fuel mixing unit 26 in the axial direction A.

In the in Fig. 1 1, the air-fuel mixing unit 26 comprises a plurality of guide elements 34 for conducting air and / or fuel vapor. As a result, the flow of both supplied air and discharged fuel vapor can be selectively influenced within the air-fuel mixing unit 26. In addition, turbulences in the flow field of supplied air and discharged fuel vapor can thereby be provided in a targeted manner, whereby a homogeneous air-fuel mixture in the air-fuel mixing unit 26 can be generated.

The arrangement of the guide elements 34 in an orthogonal to the surface normal A plane is in the sectional view of Fig. 5 shown. This representation corresponds to that represented by the line VV in FIG Fig. 1 indicated section. As in Fig. 5 1, the guide elements 34 are arranged successively about a central region Z, wherein an inflow region 32 and a flow channel 33 for air to the air-fuel mixing unit 26 are respectively defined between two immediately adjacent guide elements 34. In this embodiment, the guide elements 34 have a concave and a convex flow deflection surface 36a, 36b. By adjusting the curvature of the respective flow deflection surfaces 36a and 36b, it is possible to influence the deflection of incoming air in a targeted manner. In this case, it is possible in particular to allow air entering through the alignment of a specific guide element 34 in the air-fuel mixing unit 26 to flow onto a concave or convex flow deflection surface 36a, 36b. A baffle 34 'with an alternative arrangement within the air-fuel mixing unit 26 is shown in FIG Fig. 5 shown in dashed lines.

An alternatively configured air-fuel mixing unit 126 with alternatively configured guide elements 134 is in Fig. 6 shown. In the FIG. 6 Guide elements 134 shown differ from the guide elements 34 according to Fig. 5 by the shape of the flow deflecting surfaces 136a, 136b. Unlike the in Fig. 5 shown guide elements 34, the guide elements 134 on two straight flow deflection surfaces 136a and 136b. In this embodiment, in particular, the inlet angle of inflowing air into the air-fuel mixing unit 126 can be adjusted by the guide elements 134.

Another alternatively configured air-fuel mixing unit 226 is shown in FIG Fig. 7 shown. Similar to the guide elements 134 according to Fig. 5 also have the in Fig. 7 shown guide elements 234 of the air-fuel mixing unit 226 each have a convex and a concave flow deflecting surface 236a and 236b. Unlike in the Figures 5 and 6 shown guide elements 134, the guide elements 234 extend into the central region Z and are integrally connected to each other there. In this way, a defined relative positioning of the respective guide elements 234 to each other can be ensured. Because the only connection point in the central area Z, the flow of air and fuel to the central region Z is also not hindered.

It should also be noted for the air-fuel mixing units 126 and 226 that inflow regions 132 and 232 or flow channels 133 and 233 can also be provided between directly adjacent guide elements 134 and 234, respectively. Incidentally, it should be noted that in an air-fuel mixing unit, not all the vanes must be identical. For example, in an air-fuel mixing unit, vanes with straight flow deflecting surfaces may be combined with vanes having a convex and / or a concave flow deflecting surface.

The mixture guide assembly 28 may, as in Fig. 1 represented shell-like and be formed by the evaporation side 14 of the fuel vaporization 12 away at least partially widening. The regional expansion of the mixture guiding arrangement 28 requires, on the one hand, turbulence-generating changes in the velocity of the flowing air-fuel mixture which, in turn, result in further mixing of air and fuel vapor. On the other hand, the density of the air-fuel mixture can be influenced by the regional expansion of the mixture guiding arrangement 28 and adapted to operating parameters of downstream functional areas, such as a combustion chamber. In addition, a mixture guide arrangement 28 designed in this way can serve as an adapter between an outlet region of the air-fuel mixing unit 26 and a larger or smaller inflow region of a downstream functional region compared to this.

The mixture guiding arrangement may be formed with a different shape. This can, for example, at least partially conically and / or at least partially convex and / or at least partially concave be widening. However, it may also have tapered portions, which lead to an increase in the speed of the flowing air-fuel mixture. This can cause turbulence in the flow field of the air-fuel mixture be generated, which contribute to a further mixing of air and fuel vapor.

The mixture guide wall 30 of in Fig. 1 shown mixture guiding assembly 28 has, starting from the fuel evaporation assembly 12 has a tapered portion 35. The tapered portion 35 is adjoined by two flared portions: a first portion 36 that is closer and flared to the air-fuel mixing unit 26, and a second portion 38 that is further and concave-widening the air-fuel mixing unit 26.

An alternative designed mixture guide arrangement 128 is in FIG. 2 shown. The mixture guide wall 130 of this mixture guide arrangement 128, in contrast to the mixture guide assembly 28 according to Fig. 1 starting from the fuel evaporation arrangement 12, no tapering section, but a cylindrical section 135 with a substantially constant cross-section. At this cylindrical portion, a conically widening portion 136 connects.

Another alternative mixture guide assembly 228 is shown in FIG Fig. 3 shown. Also, the mixture guide wall 230 of the mixture guide assembly 228 according to Fig. 3 has, similar to the embodiment according to Fig. 1 , starting from the fuel evaporation assembly 12 has a tapered portion 235. At this closes, deviating from the in Fig. 1 shown mixture guide assembly 28, a convexly expanding portion 236 at.

Another alternative mixture guide assembly 328 is shown in FIG Fig. 4 shown. The mixture guide wall 330 of this mixture guide assembly 328 has, similar to the Gemischführungsanordnung 28 according to Fig. 1 , starting from the fuel evaporation assembly 12 has a tapered portion 335. At this closes, deviating from the in Fig. 1 shown mixture guide assembly 28, a concave widening portion 336 at.

It should be noted that in the FIGS. 1 to 4 shown mixture guide assemblies 28, 128, 228, 328 with the differently designed air-fuel mixing units 26, 126 and 226 of FIGS. 5 to 7 can be combined as desired.

For the purposes of the present invention, in connection with the previously described mixture-guiding arrangement, a convex widening can be understood as a progressive widening, for example as a progressively increasing flow cross-sectional area. A concave extension can be understood as a degressive extension, for example as a degressively increasing flow cross-sectional area. A conical enlargement can be understood as a constant extension, for example as a constantly increasing flow cross-sectional area.

Claims (16)

A mixed arrangement (10) for mixing fuel vapor with air, preferably for a fuel-powered vehicle heater, comprising a fuel vaporisation arrangement (12) for delivering vaporized fuel to a vaporization side (14) of the fuel vaporization assembly and at least one of the fuel vaporisation arrangement (12) on the vaporization side (14) partially oppositely disposed air-fuel mixing unit (26; 126; 226) for mixing fuel discharged at the evaporation side (14) with air. Mixing arrangement (10) according to claim 1,
characterized in that the air-fuel mixing unit (26; 126; 226) comprises at least one inflow region (32; 132; 232) leading into the air-fuel mixing unit (26; 126; 226) for supplying air into the air Fuel mixing unit (26; 126; 226). Mixing arrangement (10) according to one of the preceding claims,
characterized in that the air-fuel mixing unit (26; 126; 226) comprises at least one guide element (34, 34 ';134; 234), preferably a plurality of guide elements (34, 34';134; 234) for conducting Having air and / or fuel vapor. Mixing arrangement (10) according to claim 3,
characterized in that a plurality of guide elements (34; 134; 234) arranged successively around a central region (Z) is provided. Mixing arrangement (10) according to claim 3 or 4, characterized
characterized in that between at least two immediately adjacent guide elements (34, 34 ';134; 234), preferably between all immediately adjacent guide elements (34, 34 ';134; 234), an inflow region (32; 132; 232) is provided. Mixing arrangement (10) according to one of the preceding claims,
characterized in that the air-fuel mixing unit (26; 126; 226) is at least partially open towards the fuel vaporisation arrangement (12) and / or away from the fuel vaporising arrangement (12). Mixing arrangement (10) according to one of claims 3 to 6,
characterized in that at least one guide element (34, 34 ';134; 234) has at least one straight flow deflection surface (136a, 136b) and / or curved flow deflection surface (36a, 36b; 236a, 236b). Mixing arrangement (10) according to one of claims 3 to 7,
characterized in that at least two guide elements (234), preferably in the central region (Z) of the air-fuel mixing unit (226), are integrally formed with each other. A mixing assembly (10) according to any one of the preceding claims, characterized by a mixture guiding assembly (28; 128; 238; 338) for discharging an air-fuel mixture formed in the air-fuel mixing unit (26; 126; 226) from the air-fuel mixing unit (26; Fuel mixing unit (26; 126; 226) away. Mixing arrangement (10) according to claim 9,
characterized in that the mixture guiding arrangement (28; 128; 228; 328) is cup-shaped and at least partially widening away from the evaporation side (14) of the fuel evaporation arrangement (12). Mixing arrangement (10) according to claim 10,
characterized in that the mixture guiding arrangement (28; 128; 228; 328) is designed to widen conically at least regionally and / or at least partially convexly and / or at least partially concavely. Mixing arrangement (10) according to one of the preceding claims, characterized by a housing (16) having a bottom wall (18) and a peripheral wall (20) adjoining the bottom wall (18), wherein the fuel evaporation arrangement (12) is preferably attached to the bottom wall (18 ) is provided. Mixing arrangement (10) according to claim 12 and one of claims 9 to 11,
characterized in that a mixture guide wall (30; 130; 230; 330) of the mixture guide assembly (28; 128; 228; 328) is at least partially surrounded by the peripheral wall (20), between the peripheral wall (20) and mixture guide wall (30; 230, 330) an air inflow space (31) is provided. Mixing arrangement (10) according to one of the preceding claims,
characterized in that the fuel evaporation assembly (12) comprises a liquid fuel from a fuel supply line (22) receiving and by Kapillarförderwirkung to Abdampfungsseite transporting porous evaporation body (24). Mixing arrangement (10) according to one of the preceding claims,
characterized in that the fuel vaporisation arrangement (12) comprises a heating arrangement (13). A vehicle heater comprising a mixing assembly (10) according to any one of the preceding claims.

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