Embodiments of the invention are represented in the drawing and explained in greater detail below. In the drawing
FIG. 1 shows a cooling device according to the invention with an engine-mounted axial blower, and a radiator,
FIG. 2 shows a modified embodiment of the axial blower according to FIG. 1,
FIG. 3 shows an additional embodiment of the cooling device with a ring fan and integrated inlet nozzle, and
FIG. 4 shows an additional embodiment of a flow guidance device with a flare angle α which is variable over the periphery.
FIG. 1 shows a cooling device 1 according to the invention for a motor vehicle, which has an engine block 2 on which an axial blower 3 is attached and positioned. The axial blower 3 has a fan hub 3a with axial blade attachment 3b and a rotational axis a. The fan hub 3a is attached to a fluid friction clutch—not shown—which is driven via a belt drive system 4. (It is also possible to use a direct drive via the crankshaft of the combustion engine.) On the side of the axial blower 3 facing away from the engine block 2 is arranged a coolant/air heat exchanger 5, hereafter called a radiator, which is braced—not shown—against the body of the motor vehicle (for example, the side rails). Relative movements between the radiator 5 and the engine block 2 occur as a result. Air, represented by an arrow L, flows through the radiator 5. On the outflow side, a shroud 6, which is designed in the shape of a bonnet, is connected to the radiator 5, and guides the airflow exiting from the radiator 5 to the axial blower 3. The latter is surrounded by a shroud ring 7, which is designed cylindrically on its internal side, and which is connected, in the downstream direction, to a funnel-shaped widening flow guidance device 8. The shroud ring 7 and the flow guidance device 8 are designed as a unit in the represented embodiment. Arranged on the upstream part of the shroud ring 7 is an elastic lip 7a which lies against the shroud 6 and can slide on the latter. The shroud ring 7 is attached—not shown—to the engine block 2, while the shroud 6 is attached via an elastic fastening element 6a to the radiator 5. The fan 3, or its blade attachment 3b, has an external diameter DL. The flow guidance device 8, on its downstream end, has an external diameter DA. The two diameters DA, DL, satisfy the following inequality: 1.1≦DA/DL≦1.4, particularly 1.15≦DA/DL. The flow guidance device 8 has a conical surface 8a which forms an angle α with the axial direction (rotation axis a), this angle characterizing the measure of the radial widening of the guidance flow device 8. This so-called flare angle α is chosen to be greater than 55°, preferably greater than 60°. The geometry of the flow guidance device 8 is determined using the two above-mentioned dimensioning units DA/DL and the flare angle α. The transition from the cylindrical area of the shroud ring 7 to the conical area 8a is preferably rounded in form, i.e., it promotes flow.
The flow guidance device 8, 8a according to the invention has the effect that the air flow—represented by a dashed flow arrow P—that exits from the fan 3b is deflected outward in the radial direction. As a result, on the one hand, an accumulation of the air flow in front of the engine block 2 is prevented, and on the other hand a recirculation, i.e., a return flow in the direction of the radiator inlet 5, is also prevented.
FIG. 2 shows a cooling device 9, similar to the cooling device of 1FIG. 1, except that it has an axial blower 10 which is modified or axially offset with a hub 10a and an axial blade attachment 10b. The blades 10b have a blade overhang ü in the airflow direction with respect to the cylindrical part of the frame i.e., the blades 10b extend with their overhang ü into the radially widened conical area 8a of the flow guidance device 8. The course of the semiaxial flow over the blades 10b, and the outflow in the area of the flow guidance device 8 are represented by a dashed flow arrow S. This variant with the blade overhang u promotes a low-loss outflow with subsequent radial deflection, and stabilizes the flow.
FIG. 3 shows, as an additional embodiment of the invention, a cooling device 11 in which a shroud 12, a shroud ring 13, and a flow guidance device 14 are formed as a single plastic injection-molded piece. In addition, an inlet nozzle 15 is overmolded in the inlet area of the shroud ring 13, as described in a similar form in the state of the art mentioned in the introduction. The axial blower 16 is designed as a so-called ring fan, i.e., a shell or guide ring 17 is arranged on the circumference of the blade 16b and is connected to the blade tips. As is also known from the state of the art, the guide ring 17 has an overhang on the inlet side that extends into the inlet nozzle 15. As a result, a 180° direction change is achieved. The guide ring 17 has a part 17b on the outflow side which is widened conically and forms a transition to the adjoining flow guidance device 14. An annular gap 18 is thus formed between the guide ring 17 and the shroud ring 13 which develops a gap flow opposite the main flow in the fan. The inlet nozzle 15, in connection with the guide ring 17, improves the flow conditions in the blade tip area, reduces the noise level, and decreases the leakage flow. In addition, the aspiration of the gap flow in the downstream area of the fan results in a greater deceleration of the main flow and a better application of the flow against the flow guidance device 14. The gap flow thus has the known effect of aspiring a boundary layer. For the rest, the cooling device 11 corresponds to the cooling device 1 according to FIG. 1.
The injection molded part which consists of the shroud 12, the shroud ring 13, the flow guidance device 14, and the inlet nozzle 15, is connected by braces, which are not shown, to the engine block 2. Therefore there are practically no relative movements at all between the guide ring 17 and the shroud ring 13, so that a minimal annular gap 18 can be achieved. However, an elastic or movable fastening of the shroud 12 to the radiator 5 is required, and it is preferably achieved using an elastic fastening element 12a.
In contrast to the embodiments represented in the drawing, which has a conical or cone-shaped surface 8a of the flow guidance device 8, a bell- or flare-shaped form is also possible and within the scope of the invention.
FIG. 4 shows, as an additional embodiment of the invention, a cooling device 20 with a combustion engine 21 that has several secondary units 22 in the front-end area for example, a coolant pump and a generator that are connected by a belt drive to each other. The front of the combustion engine 21 presents a relatively jagged and irregular design due to the arrangement of the secondary units 22. A driver cab 23 is arranged above the combustion engine 21, which closes off the motor space at the top. In front of the secondary units 22 in the driving direction, an axial blower 3 and a radiator 5, or a cooling module formed from several heat exchangers, are/is arranged. Arranged between the radiator 5 and the axial blower 3 is a shroud 24 with a shroud ring 25 in which the axial blower 3 turns. Connected to the shroud ring 25 is a flow guidance device 26 which, seen over the circumference of the shroud ring 25, has a varying flare angle α: in the drawing, for example, two different flare angles are represented, an upper flare angle α1 of approximately 90°, and a bottom flare angle α2 of approximately 55°. The flow guidance device 26 is thus adapted to the different outflow conditions to the rear of the axial blower 3, where the conditions result from the arrangement of the secondary elements 22. A low-resistance outflow of the cooling air is achieved as a result of this variable design of the flare angle α over the circumference.
Patent Application
20080035316
