EP2236837B1 - Axial ventilator, in particular for a motor vehicle - Google Patents

Description

The invention relates to an axial fan according to the preamble of claim 1. Such axial fan is in the JPH 07 217 434 shown. Axial fans are used as cooling fans in motor vehicles, wherein the axial fan is arranged in the air flow direction behind a heat exchanger or a group of heat exchangers and sucks ambient air for Kühiungszwecken by the one or more heat exchangers. The axial fan runs in a Zargenring, ie a stationary casing, wherein the Zargenring is part of a frame or fan cowl, which adjoins the heat exchanger or the group of heat exchangers. In the air flow direction behind the axial fan, ie in its outflow field, the internal combustion engine of the motor vehicle and auxiliary units of the internal combustion engine are arranged, forming the non-uniform obstacles in the outflow of the axial fan. Due to the usual compact design in the engine compartment of the motor vehicle, these obstacles, in particular the internal combustion engine are arranged at a small axial distance behind the axial fan, which may result in blocking effects, in particular a pressure drop through a stronger throttling, but also a pressure recovery by diffuser effect. In addition, the air flow emerging from the axial fan is subject to a swirl, which can not be used for an additional pressure build-up - rather the associated energy is dissipated. Finally, the problem often occurs the recirculation, ie the Wiederaugaugung of heated, leaked from the axial fan air. This leads to a deterioration of the cooling performance.

Because of these problems has already been proposed to influence the flow field of the axial fan targeted, z. B. by a so-called Nachleitapparat or Nachteitelemente.

By the EP 1 443 216 A2 which of the US 6,827,547 B2 corresponds, a cooling system for an internal combustion engine of a motor vehicle was known, wherein a circulating in a Zargenring axial fan, a diffuser and exit-side flow guide elements are connected downstream. The Zargen ring, which adjoins a fan cowl or frame surrounds the fan blades of the axial fan over its entire depth (axial extent), and the substantially radially extending Strömungsleitelemente are arranged in the air flow direction behind the trailing edges of the fan blades, ie downstream of the fan exit plane. This results in a disadvantage, a relatively large axial depth, as add the depth of the fan blades and the depth of the flow guide in the axial direction.

By the DE 10 2006 037 628 A1 the applicant has been known a stationary arranged Nachleitapparat for an axial fan, which is arranged between a designed as a coolant radiator heat exchanger and an internal combustion engine. The Nachleitapparat comprises on the one hand a diffuser and on the other hand substantially radially extending flow guide elements, which extend from the root of the fan blades to the outer diameter of the diffuser. The radial flow guide elements as well as the diffuser are arranged downstream of the fan exit plane, so that a relatively large axial installation depth also results here. This also applies to a further embodiment in which radially extending flow guide surfaces are arranged radially outside the fan and the Zargenringes.

It is an object of the present invention to improve an axial fan of the type mentioned in terms of its fan performance, in particular by deliberate influencing its outflow field, at the same time a squat design in the axial direction should be achieved.

The object of the invention is solved by the features of claim 1. Advantageous embodiments emerge from the subclaims.

According to the invention, it is provided that the fan blades form a blade overhang relative to the frame ring and that flow guide elements are arranged radially outside the fan blades and in the area of the blade projection. The blade tips of the fan blades are thus not sheathed in the outflow region, the area of the blade projection, the Zargenring, but run free in this area. Due to the blade projection, a radially directed fan outflow already forms in the blade tip region, which impinges on the flow guide elements arranged radially outside. This achieves the advantage that the flow generated by the fan in the blade tip region delays, that the swirl is taken out of the fan outflow and converted into static pressure (pressure recovery). The energy of the swirl flow in Lüfterabströmfeld is thus not lost.

According to a preferred embodiment, the flow guide elements are substantially radially aligned, or they have a radial and tangential course. The fan exhaust air can thus be dissipated lossless from the engine compartment. As a result, the conversion of the swirl flow is effected in static pressure, and the outflowing air is advantageously derived.

The flow guide elements preferably have curved guide surfaces, wherein a two-dimensional curvature or also a three-dimensional curvature can be advantageous. Two-dimensional curvature means that parallel radial sections have the same curvature - such as in a cylindrical surface. Three-dimensional curvature means that parallel radial sections through the flow guide surfaces do not have the same but different curvatures. For example, the flow control surfaces are additionally wound in the axial direction.

According to a particularly preferred embodiment, the flow guide elements are arranged distributed in sections or in groups on the circumference. For example, a first group of flow directors may be disposed above the fan, while a second group of flow directors may be approximately diametrical to the first group, i. H. is arranged in the lower fan area. The selective arrangement and the individual geometry of the flow guide elements takes place in adaptation to the local outflow field, d. H. the arrangement and design of the downstream flow obstacles such as internal combustion engine and their additional aggregates. This achieves high efficiency in reducing pressure losses with minimal structural complexity. According to the invention, the flow guide elements with their trailing edges are flush with the trailing edges of the fan blades. Thus, a gain in axial space is achieved, since the flow guide elements are thus arranged within the axial depth of the fan blades. According to the invention, the axial depth of the flow guide elements corresponds to the blade projection. This results in an optimal interaction of the blade tip flow with the flow guide elements.

According to a further preferred embodiment, the outlet side of the Zargenringes is formed as a diffuser. Thus, a further pressure gain is achieved by delaying the fan outlet flow, with support the flow guide and the diffuser in their effect.

Preferably, the flow guide are attached to the Zargenring, which is possible without great structural complexity Particularly preferably, the flow guide can be integrated into the Zargenring and integrally formed therewith, preferably as a plastic injection molded or injection-molded assemblies are screwed to a metal ring.

In a further preferred embodiment, the axial fan is attached to the internal combustion engine of a motor vehicle and is driven by the internal combustion engine, for example directly by the crankshaft or via an intermediate drive. The axial fan is thus arranged fixed to the engine, which is particularly advantageous for commercial vehicles.

According to a further preferred embodiment, the Zargenring and the flow guide are attached to the internal combustion engine. Thus, no or only minimal relative movements between the fan blade tips and the Zargenring occur, so that a minimum circumferential gap is feasible, which benefits the fan efficiency.

According to an alternative embodiment, the axial fan, the Zargenring and the flow guide elements on a frame or fan cowl of a heat exchanger, preferably a coolant radiator of an internal combustion engine of a motor vehicle to be attached, d. H. the axial fan is arranged "cooler". In this case, the axial fan is preferably driven by an electric motor, which in turn is attached to the fan cover. The cooler-resistant arrangement is for axial fans with lower weight, d. H. advantageous for smaller vehicles.

Fig. 1a

einen Axiallüfter mit Strömungsleitelementen an einem Zargenring in einer Ansicht von hinten,

Fig. 1b

den Axiallüfter gemäß Fig. 1 a in einer seitlichen Ansicht,

Fig. 1c

eine vergrößerte Einzelheit des Axiallüfters gemäß Fig. 1b als Schnittbild,

Fig. 2a

ein zweites Ausführungsbeispiel der Erfindung mit partiell im Umfangsbereich eines Axiallüfters angeordneten Strömungsleitelementen in einer Ansicht von hinten,

Fig. 2b

einen Axialschnitt des Axiallüfters gemäß Fig. 2a mit einem Strömungsleitelement in drei Ansichten und

Fig.3

eine perspektivische Ansicht des Axiallüfters mit partiellen Strömungsleitelementen von vorn mit rückseitiger Brennkraftmaschine.

Embodiments of the invention are illustrated in the drawings and will be explained in more detail below, which may result from the description and / or the drawing further features and / or advantages. Show it

Fig. 1a

an axial fan with flow guide elements on a frame ring in a view from behind,

Fig. 1b

the axial fan according to Fig. 1 a in a side view,

Fig. 1c

an enlarged detail of the axial fan according to Fig. 1b as a cross section,

Fig. 2a

A second embodiment of the invention with partially arranged in the peripheral region of an axial fan flow guide elements in a view from behind,

Fig. 2b

an axial section of the axial fan according to Fig. 2a with a flow guide in three views and

Figure 3

a perspective view of the axial fan with partial flow guide from the front with back-end internal combustion engine.

Fig. 1a, 1b, 1c show as the first embodiment of the invention, an axial fan 1, which in a stationary arranged Zargenring 2 (also called guide ring or jacket), is rotatably arranged. The axial fan 1 comprises fan blades 3 designed as axial blades and a fan hub 4, which is connected to a fan clutch, not shown, preferably a fluid friction clutch. The axial fan 1, hereinafter also referred to as fan 1 for short, is fastened in relation to an internal combustion engine, not shown, of a motor vehicle and is preferably driven directly by the internal combustion engine, ie via an unillustrated crankshaft of the internal combustion engine. An indirect drive via a trained example as V-belt drive intermediate drive is also possible. The axial fan 1 is thus arranged fixed to the motor. The Zargenring 2 has a substantially cylindrically shaped annular surface 2a, the fan blades 3 in the axial direction, that is partially coated in the direction of the fan axis. The annular surface 2a is in the axial direction ( Fig. 1c ) bounded by a front edge 2b and a trailing edge 2c. The fan 1 and the frame ring 2 are separated from ambient air in the direction of an arrow L (FIG. Fig. 1b ) flows through. On the downstream side of the Zargenringes 2, the back 2 d, distributed over the circumference flow guide elements 5 are arranged, which have a two-dimensional curvature about axially parallel axes. The flow guide elements 5 form blade-like, extending in the radial and tangential direction cylindrical surfaces. In the illustrated embodiment ( Fig. 1a ), the flow guide elements 5 are arranged distributed uniformly over the circumference.

As in particular in Fig. 1c recognizable, the back 2d of the Zargenringes 2 is conical and thus forms a diffuser 6 for the exiting the fan 1 air flow. The fan blades 3 have outflow edges 3b, which project beyond the frame ring 2 in the air flow direction L. The distance between the trailing edge 2c of the annular surface 2a and the trailing edge 3b of the fan blades 3 is referred to as blade projection ü. The blade tips 3a are therefore not encased in the region of the blade projection ü by the annular surface 2a, but arranged free-running. The flow guide elements 5 are arranged in the axial region of the blade projection ü and have trailing edges 5a, which terminate flush with the trailing edges 3a, ie the trailing edges 3b of the fan blades 3 and the trailing edges 5a of the flow guide elements 5 lie in a common radial plane. This means that the flow guide 5 compared to the (axial) depth of the fan blades 3 claim no additional axial space. The blade projection is preferably 15 to 60% of the total depth of the fan blades 3.

The Zargenring 2 and the flow guide 5 can be integrally formed according to a preferred embodiment, in particular as a plastic injection molded part.

In the following, the mode of action of the axial fan 1 in connection with the frame ring 2 and the flow guide elements 5 will be described, with particular reference to the illustration in FIG Fig. 1c Reference is made: The entering according to arrow L in the Zargenring 2 air impinges on the rotating driven by the engine fan blades 3. In the flow direction behind the fan 1 is the internal combustion engine, not shown, by which a free outflow is obstructed. This leads to a throttling and an approximately semiaxially formed flow in the fan 1. Particularly in the area of the blade tips 3a, which project beyond the trailing edge 2c of the annular surface 2a and thus run free, a radially directed outflow forms, which strikes the flow elements 5 , The air flow exiting via the blade tips 3a is subject to a strong swirl, which is taken out of the air flow by the stationary flow guidance elements 5 and converted into static pressure. At the same time occurs due to the diffuser 6 a controlled delay of the outflow. The fan outflow is thus deflected in the radial direction. The conversion of the dynamic pressure into static pressure achieves a pressure recovery and thus a higher fan performance.

Fig. 2a and Fig. 2b show as a second embodiment of the invention, an axial fan 7, which rotates in a stationary, preferably motor-fixed arranged Zargenring 8. The axial fan 7 points to a fan hub 9 fixed fan blades 10, which in the axial direction over a depth T ( Fig. 2b ). The frame ring 8 has a cylindrically shaped region 8a, which surrounds the fan blades 10 in their upstream region and terminates approximately flush with a fan inlet plane EE. The fan blades 10 protrude in the air flow direction L beyond the cylindrical region 8a and form a blade projection Ü, which is preferably in a range of 15 to 60% of the depth T of the fan blades 10. In the area of the blade projection Ü the fan blades 10 are thus not sheathed, ie the blade tips 10a run free. In the axial region of the blade projection Ü, a flow-guiding element 11 is arranged radially outside the blade tip 10a, which is additionally shown as a flow-guiding element 11a in a view from below and as a flow-guiding element 11b in a view from the rear. From the illustrations 11, 11a, 11b shows that the flow guide 11 is curved three-dimensionally, ie parallel radial sections (perpendicular to the fan axis) through the flow guide 11 have different curvatures, in particular a twist in the axial direction.

Fig. 2a shows a rear view of the arrangement of the flow guide elements 11 on the circumference of the Zargenringes 8. A first group I of ten flow guide elements 11 (the number 10 is an example) is disposed in the upper region of the axial fan 7, and a second group II of six Flow guide elements 11 (the number 6 also as an example) is arranged in the lower, lateral region of the axial fan 7. For fixing the flow guide elements 11, the frame ring 8 has radially extending flange sections 8b. The arrangement of the flow guide elements 11 in groups I, II, that is distributed in sections on the circumference of the Zargenringes 8, takes place in adaptation to the downstream of the axial fan 7, disturbed by flow obstacles Abströmfeld. Thus, a targeted, effective influencing the fan flow is realized, by selective arrangement of the flow guide elements 11 on the circumference, by their number on a peripheral portion and optionally by a different geometry (curvature) of the guide surfaces of the flow guide 11. The latter need not, though denoted by the same reference numeral 11, have an identical geometry.

Fig. 3 shows a perspective view from the front of the axial fan 7 according to Fig. 2a and Fig. 2b including Zargenring 8 and attached thereto, arranged in groups I, II flow guide 11. The axial fan 7 is fixed to an internal combustion engine 12 and is driven above a crankshaft, not shown, and a fan hub 9 connected to the fan clutch 13. The frame ring 8 and the attached flow guide elements 11 can - which is not shown - also be connected to the internal combustion engine 12. This results in the advantage that a narrow circumferential gap can be maintained between the axial fan 7 and the frame ring 8. The internal combustion engine 12 is located in the outflow field of the axial fan 7 and represents a significant interference obstacle for the exiting fan flow. In particular in the upper area 12a there is a "blocking" of the fan exhaust field. For this reason, the flow guide elements 11 are arranged in a group I just in the upper region of the axial fan 7. As a result, the "blocking" is "neutralized" by the upper region 12a of the internal combustion engine 12, in that the air flow emerging from the fan 7 in the region 12a is selectively deflected into a radial or also a radial and a tangential flow direction. The fan outlet air can thus be specifically led out of the engine compartment past the mentioned flow obstacles and with substantially reduced pressure losses. In addition, a recirculation and re-suction of already heated air can be avoided in this way. By the second group II of flow guide elements 11 in a peripheral region which is arranged approximately diametrically to the arrangement of the first group I, a locally limited, adapted to the downstream flow conditions influencing the fan outflow is also achieved. The arrangement of the groups I, II shows an embodiment of many possible, ie in a different "silhouette" of the internal combustion engine and its auxiliary units may be required a different arrangement and design of the air guide elements.

Notwithstanding the illustrated embodiments, in which the axial fan is arranged fixed to the engine and driven by the internal combustion engine, is also a variant embodiment within the scope of the invention, in which the axial fan is arranged "cooler solid", that is connected via a radiator frame (also called fan cowl) with a designed as a coolant radiator heat exchanger and secured against this. The drive of the axial fan would in this case preferably take place via an electric motor also connected to the fan hood.

Claims (13)

1. An axial flow fan, which is arranged in a rotatable manner around an axis in a stationary shroud ring (2, 8), with fan blades (3, 10), wherein the shroud ring (2, 8) has an essentially cylindrical annular surface (2a, 8a) with an axial extension from a leading edge (2b) to a trailing edge (2c) and the fan blades (3, 10) have an axial depth (T) from an inflow edge to an outflow edge (3b), wherein the outflow edges (3b) of the fan blades (3) in the axial direction project beyond the trailing edge (2c) of the annular surface (2a) and form a blade overhang (ü, Ü), and wherein flow guidance elements (5, 11) are arranged radially outside the fan blades (3, 10) as well as in the axial region of the blade overhang (ü, Ü), characterised in that the flow guidance elements (5) have trailing edges (5a) which are arranged flush with the outflow edges (3b) of the fan blades (3) and the flow guidance elements (5, 11) have an axial extension that corresponds to the blade overhang (ü, Ü).
2. The axial flow fan according to claim 1, characterised in that the flow guidance elements (5, 11) are aligned essentially radially or radially and tangentially.
3. The axial flow fan according to claim 2, characterised in that the flow guidance elements (5, 11) have curved guide surfaces.
4. The axial flow fan according to claim 3, characterised in that the guide surfaces are curved in a two-dimensional manner.
5. The axial flow fan according to claim 3, characterised in that the guide surfaces are curved in a three-dimensional manner.
6. The axial flow fan according to one of claims 1 to 5, characterised in that the flow guidance elements (11) are arranged in sections on the circumference of the shroud ring (2a, 8a) and are adapted to the local outflow field behind the axial flow fan (7).
7. The axial flow fan according to one of the preceding claims, characterised in that the shroud ring (2) is configured as a diffuser (6) on an outflow side.
8. The axial flow fan according to one of the preceding claims, characterised in that the flow guidance elements (5, 11) are attached to the shroud ring (2, 2d; 8, 8b) individually or as groups.
9. The axial flow fan according to claim 8, characterised in that the flow guidance elements (5) are configured as one piece with the shroud ring (2), preferably as a plastic injection moulded part.
10. The axial flow fan according to one of the preceding claims, characterised in that it is attached to and is drivable by an internal combustion engine (12) of a motor vehicle.
11. The axial flow fan according to claim 10, characterised in that the shroud ring (8) and the flow guidance elements (11) are attached to the internal combustion engine (12).
12. The axial flow fan according to one of claims 1 to 9, characterised in that the axial flow fan, the shroud ring and the flow guidance elements are attached to a fan cowl of a heat exchanger, in particular of a coolant radiator for an internal combustion engine of a motor vehicle.
13. The axial flow fan according to claim 12, characterised in that it is drivable by an electric motor attached to the fan cowl.

Images