Fan assembly for a motor vehicle

Abstract

The invention relates to a fan assembly (6) for cooling an internal combustion engine (4) of a motor vehicle, in particular a hybrid vehicle, comprising: a first cooling fan, which is arranged, with respect to an air flow direction (5), downstream of a heat exchanger (2) through which a coolant flows; and a second cooling fan, wherein: the first cooling fan is a radial fan (6a), which draws cooling air (L) in axially and expels it radially; the second cooling fan is an axial fan (6b), which draws cooling air (L) in axially and expels it axially; and the axial fan (6b) is arranged downstream of the heat exchanger (2) and laterally adjacent to the radial fan (6a) in a plane parallel to the rear side (7) of the heat exchanger, or is arranged upstream of the heat exchanger (2), with respect to the air flow direction (5), in a plane parallel to the front side (8) of the heat exchanger.

Description

[0001] The invention relates to a fan assembly for cooling the internal combustion engine of a hybrid vehicle, comprising at least one cooling fan arranged in an airflow direction downstream of a heat exchanger (radiator) through which a coolant flows. It further relates to a method for operating the fan assembly. A hybrid vehicle is understood to be a motor vehicle with an internal combustion engine and an electric motor powered by a rechargeable battery as the electric motor drive.

[0002] The cooling system of an internal combustion engine in a hybrid vehicle primarily dissipates the heat that is released into the combustion chamber or cylinder walls. Since excessive temperatures would damage the engine, the internal combustion engine must be cooled. Modern internal combustion engines, especially four-stroke engines in motor vehicles, are, with only a few exceptions, liquid-cooled. A mixture of water, antifreeze, and corrosion inhibitors is typically used as the coolant to maintain the engine's operating temperature and also to operate the air conditioning system.

[0003] The coolant, which is guided through pipes incorporated into the cooling network of a radiator, must in turn be cooled. For this purpose, cooling air passes over cooling fins that exchange heat with the coolant. Since the airstream serving as cooling air is normally not sufficient for cooling, particularly at low vehicle speeds, it is known, for example from DE 10 2013 006 499 U1, to arrange an axial fan within a radiator shroud on the radiator comprising the cooling fins. The axial fan, which is preferably driven by an electric motor, generates an additional airflow, with the radiator shroud having a number of air flow flap openings that can be closed with air flow flaps. With air flow flaps open and at comparatively high vehicle speeds, the cooling surface coverage is reduced due to less blockage and there is a large area for free flow, thus increasing cooling performance.

[0004] The fan is typically positioned behind the radiator core (heat exchanger) in the direction of travel. The fan's impeller draws air through the radiator core and directs it toward the combustion engine. If, in addition to the radiator core, there is also a condenser core for an air conditioning system, the condenser core is usually positioned in front of the radiator core in the direction of travel (airflow direction). The fan's impeller is located in a circular recess in the fan shroud body, through which the air is directed through the radiator core. The shroud body essentially completely covers the radiator core.

[0005] US Pat. No. 5,845,612 A discloses a fan assembly for cooling a motor vehicle's internal combustion engine. The assembly comprises an electric motor-driven fluid pump and an axial fan arranged upstream of the heat exchanger in the air flow direction, as well as two radial fans arranged downstream of the heat exchanger. A sensor signal indicates the operating state of the motor vehicle to the control module, enabling the electric motors of the fluid pump and the fans to operate with minimal energy consumption and targeted convective heat transfer.

[0006] DE 10 2004 028 697 A1 discloses a cooling module with an axial fan facing in the direction of travel (of the motor vehicle) behind the radiator (i.e. on the rear thereof) and with another fan. This is a cross-flow fan with a fundamentally different operating principle than a radial fan. In contrast to the radial fan according to the invention, the cross-flow fan draws in the air radially (or tangentially) rather than axially. And after a 90° deflection, the cross-flow fan, unlike the radial fan according to the invention, flows (blows) the air out axially rather than radially into the downstream radiator. Furthermore, in the known cooling module, the cross-flow fan is arranged in front of the radiator (i.e. on the front thereof) in the direction of travel (of the motor vehicle), unlike the radial fan according to the invention.

[0007] To achieve high fan efficiency, the frame body is essentially airtight, except for the circular recess. This means that the pressure difference between the area in front of the radiator core and the area behind the frame body—both viewed in the direction of travel of the vehicle—is comparatively large. When the vehicle is stationary, a comparatively large volume of air is drawn through the radiator core by the axial fan. As soon as the vehicle is moving at a comparatively high speed, the airflow is dammed in front of the frame body and the radiator core. Consequently, only a certain proportion of the airflow passes through the radiator core.

[0008] To solve this problem, the fan shroud body incorporates vents, each of which can be closed with a vent flap. When the fan is operating while the vehicle is stationary, the vent flaps are closed by the vent flaps, resulting in a comparatively large pressure difference between the area in front of and behind the fan shroud. As soon as the vent flaps are exposed to airflow, i.e., as soon as the vehicle is moving, they pivot into an open position, and the airflow flows not only through the recess for the fan impeller but also through the vent flap openings. This increases the volume of air flowing through the radiator core.

[0009] The invention is based on the object of providing a particularly suitable fan assembly (fan module) for a hybrid vehicle with an internal combustion engine and an electric motor drive. Furthermore, a method for operating such a fan assembly is to be provided, which operates as effectively (power-effectively) as possible in all operating ranges of the hybrid vehicle. In particular, the noise generated by the fan assembly (the fan module) should be as low as possible during charging of the battery of a provided electric motor drive, thus operating as quietly as possible.

[0010] This object is achieved according to the invention with regard to the fan arrangement having the features of claim 1 and with regard to the method having the features of claim 4. Advantageous embodiments and further developments are the subject of the subclaims.

[0011] For this purpose, the fan arrangement for cooling the internal combustion engine of a hybrid vehicle with the internal combustion engine and an electric motor powered by a rechargeable battery has a first and a second cooling fan. The first cooling fan is a radial fan which axially draws in the cooling air flowing through a radiator, i.e. a heat exchanger through which a coolant flows, and - after deflection (90° deflection) - radially discharges it, i.e. conveys it outwards (blows it out) in a radial direction. The second cooling fan is an axial fan which axially draws in the cooling air and axially discharges it, i.e. conveys it outwards (blows it out) in an axial direction.

[0012] "Axial" refers to a direction parallel (coaxial) to the axis of rotation (axial direction) of the axial and / or radial fan, and "radial" refers to a direction perpendicular (transverse) to the axis of rotation (radial direction) of the axial or radial fan. The fan axes of rotation, in turn, run in the direction of travel of the vehicle and thus parallel to the direction of travel.

[0013] The radiator, i.e., the heat exchanger through which the coolant flows, has a front and a rear side relative to the direction of travel of the vehicle, i.e., relative to its main direction of movement and the resulting airstream (airstream / airflow direction). The airstream, which can be amplified by the fan arrangement, strikes the radiator (heat exchanger) at its front and exits at the rear after flowing through it. This leads to cooling of the coolant and, if necessary, to additional cooling of the combustion engine.

[0014] According to a first variant of the fan arrangement for cooling the internal combustion engine of the hybrid vehicle with an electric motor powered by a rechargeable battery, comprising a first cooling fan arranged in an air flow direction behind a heat exchanger through which a coolant flows, and a second cooling fan, wherein the first cooling fan is a radial fan which axially sucks in cooling air and radially discharges it, and wherein the second cooling fan is an axial fan which axially sucks in cooling air and radially discharges it, the axial fan is arranged behind the heat exchanger in a plane parallel to the rear of the heat exchanger laterally next to the radial fan.

[0015] According to a second variant of the fan arrangement, the axial fan is arranged in front of the heat exchanger in the air flow direction, preferably in a plane parallel to its front side.

[0016] In other words, the axial fan is arranged behind the cooler or heat exchanger in the direction of cooling air flow and in a plane parallel to its rear. With this axial fan arrangement, the radial fan is positioned laterally next to the axial fan in a plane parallel to the rear of the heat exchanger (cooler). Alternatively, the axial fan is arranged in front of the heat exchanger (on the front of the cooler) in the direction of air flow, while the radial fan is arranged behind the heat exchanger (on the rear of the cooler). In both variants, the axial intake opening of the radial fan faces the cooler or heat exchanger, i.e., its rear.

[0017] In an advantageous embodiment, the axial fan and the radial fan of the fan assembly according to the invention are driven by an electric motor. For a particularly space-saving design of the axial fan and the radial fan, in particular for the smallest possible size of the cooling fans in the axial direction, the electric motors used to drive their impellers are suitably arranged in a fan hub of a radial impeller of the radial fan and in a fan hub of an axial impeller of the axial fan.

[0018] Particularly when the axial fan and the radial fan are arranged in the same plane behind the heat exchanger, the axial fan and the radial fan are advantageously arranged in a common fan shroud. The rotational axes of the axial impeller of the axial fan and the rotational axes of the radial impeller of the radial fan run parallel. If the radial fan and the axial fan are arranged one behind the other—with the cooler (heat exchanger) in between—their rotational axes are suitably coaxial.

[0019] Due to the arrangement of the axial fan on the front and the radial fan on the back of the cooler (heat exchanger), the surface coverage (blocking) of the cooler surface is low compared to a reverse arrangement, namely an arrangement of the radial fan on the front and the axial fan on the back of the cooler, especially since when only the radial fan is operating there is a sufficiently large flow area through the axial fan and its impeller can rotate freely without a drive, which further reduces the flow resistance.

[0020] A control device is assigned to the fan assembly, which is designed and configured to operate the axial fan and the radial fan, or only the axial fan, or only the radial fan, depending on the driving mode (driving cycle) or the operating range of the motor vehicle. For this purpose, the electric motors, which drive the axial impeller of the axial fan or the radial impeller of the radial fan, are supplied with current accordingly. The control device can be separate or, in particular, integrated into the electric motors with individual functional modules.

[0021] A vehicle speed threshold is specified, above which only the axial fan is operated, and below which only the radial fan is operated when the battery is being charged for the electric motor drive of the hybrid vehicle. Operating only the radial fan when the existing battery is being charged for the electric motor drive of the hybrid vehicle is particularly advantageous because the radial fan is characterized by very low noise emissions, thus operating particularly quietly. During charging, the ratio of (aerodynamic) cooling capacity to (electrical) power consumption is particularly favorable for the electric motor-driven radial fan, meaning the radial fan operates particularly efficiently.

[0022] At higher, higher, and / or maximum vehicle speeds, i.e., during high-speed travel or when the combustion engine is subjected to high loads, e.g., when driving uphill and / or when additional stress is imposed on the vehicle by a trailer, operation of both the axial fan and the radial fan (dual fan operation) is particularly suitable. The axial fan can be comparatively small (compact with small dimensions) or comparatively low-performance, with a particularly optimized characteristic. Furthermore, the axial fan can be designed to meet only one (single) aerodynamic operating point.

[0023] In the method for operating such a fan arrangement, the axial fan and the radial fan are operated jointly or individually depending on the operating range, the combustion engine load, the respective driving cycle, and / or the speed of the motor vehicle. According to an advantageous development, the axial fan and the radial fan can be operated above a threshold speed of the motor vehicle, for example, during high-speed travel, and only the axial fan or only the radial fan can be operated below the threshold speed, for example, during low-speed travel, for example, when the vehicle is stationary and when the battery of the hybrid vehicle with combustion engine and electric motor drive is being charged.

[0024] The advantages achieved by the invention are, in particular, that by providing a fan arrangement with an axial fan and a radial fan, virtually all driving situations and operating ranges of a hybrid vehicle are covered while providing a cooling air flow sufficient for reliable cooling. The axial fan and the radial fan can operate within their respective optimal efficiency ranges while simultaneously maintaining low noise levels, especially at low vehicle speeds.

[0025] For high-temperature requirements, combined operation with an axial fan and a radial fan is suitable. In combination with various coolers, suitable partitioning or blocking can achieve high efficiency and thus better cooling and improved exhaust emissions.

[0026] In a hybrid vehicle, it is also suitable to operate the vehicle with just the axial fan or, in the case of high temperature requirements, with both the axial fan and the radial fan. When the vehicle is stationary and the battery is charged, it is suitable to operate just the radial fan, especially since it then operates efficiently and very quietly.

[0027] In the following, exemplary embodiments of the invention are explained in more detail with reference to a drawing. In the drawings: Fig. 1 schematically simplified a cooling fan with a fan arrangement with radial and axial fans, Fig. 2 in perspective view the fan arrangement according to a first variant with the radial fan and the axial fan on the back of a cooler, Fig. 3 in perspective view the fan arrangement according to a second variant with a radial fan on the back and an axial fan on the front of a cooler, with a view of the axial fan, and Fig. 4 in perspective view the fan arrangement according to the second variant with a view of the radial fan.

[0028] Corresponding parts are provided with the same reference numerals in all figures.

[0029] In Fig. 1A simplified schematic side view of a radiator or radiator fan system 1 of a motor vehicle (not shown in detail) is shown. The radiator fan system 1 comprises a heat exchanger, referred to below as the radiator 2, to which cooling pipes or cooling hoses 3 are routed. Inside the cooling pipes 3 there is a coolant (a cooling liquid) K, which is kept in circulation by means of a pump (not shown). The coolant K is passed through an internal combustion engine 4 and heated by it, cooling the internal combustion engine 4. The heated coolant K is passed again through the radiator 2, which is subjected to a headwind. The direction of the headwind is along a headwind direction, which essentially corresponds to the main direction of travel of the motor vehicle and is referred to below as the airflow direction 5.

[0030] By means of a fan arrangement 6, the airflow is amplified or generated when the motor vehicle is stationary. The fan arrangement 6 comprises a radial fan 6a and an axial fan 6b. In a preferred embodiment, the radial fan 6a and the axial fan 6b are arranged on the rear side 7 of the radiator 2 and are located there next to each other in a plane parallel to the rear side 7 of the radiator 2, ie perpendicular to the plane of the drawing of the Fig. 1 one after the other.

[0031] According to an alternative, the radial fan 6a is arranged behind the cooler 2 in the air flow direction 5 and thus again on its rear side 7, while the axial fan 6b is arranged in front of the cooler 2 in the air flow direction 5 and there again in a plane parallel to its front side 8. The radial fan 6a and the axial fan 6b are each driven by an electric motor 9 and 10, respectively, i.e., by an electric motor.

[0032] A control device 11 adjusts the operation of the radial fan 6a and the axial fan 6b. This means that the control device 11 activates the radial fan 6a or the axial fan 6b, or both the radial fan 6a and the axial fan 6b, via corresponding control signals SR, SA. This occurs depending on the driving situation, the respective work area, the workload (e.g., when driving uphill and / or when towing a trailer), and preferably depending on the speed of the vehicle. Thus, both the radial fan 6a and the axial fan 6b are suitably activated for operation at high or maximum vehicle speed (high-speed driving) and / or at particularly high temperature loads (high-temperature requirements). For this purpose, their respective electric motors 9, 10 are supplied with current accordingly.

[0033] At comparatively low vehicle speeds, for example, only the axial fan 6b can be operated. When traveling slowly or when the vehicle is stationary, operating only the radial fan 6a is particularly suitable, especially since it operates efficiently and very quietly.

[0034] In the case of the hybrid vehicle with, in addition to the combustion engine 4, a further drive machine in the form of an electric motor 12, it is particularly advantageous to operate only the radial fan 6a during a charging process of a battery 13, which supplies the electrical current required for the operation of the electric motor 12.

[0035] In principle, the operation of the fan arrangement 6 is such that while the vehicle is moving, only the axial fan 6b or this and the radial fan 6a are operated, while when the vehicle is stationary and the battery 13 is being charged to supply the electric motor 12, only the radial fan 6a is operated.

[0036] The radial fan 6a draws in the cooling air L via the cooler 2, deflects it by 90°, and expels (blows) the deflected cooling air L radially. This is illustrated by the flow arrows 14. The axial fan 6b draws in the cooling air L axially and expels (blows) it axially. This is illustrated by the flow arrows 15, 16.

[0037] Particularly in the embodiment with radial and axial fans 6a and 6b arranged side by side on the rear side 7 of the cooler 2, these are suitably arranged in a common fan frame 17. In this way, a particularly suitable dual fan module with radial fan 6a and axial fan 6b can be provided.

[0038] In the embodiment with axial and radial fans 6b and 6a arranged one behind the other in the air flow direction 5, a common cooler frame can also be provided. This is then designed such that, when the cooler 2 is mounted, the axial fan 6b is positioned on its front side 8 and the radial fan 6a is positioned on its rear side 7.

[0039] Fig. 2shows the fan arrangement 6 with radial fan 6a and axial fan 6b arranged side by side in a plane parallel to the rear side 7 of the cooler 2 in the common fan frame 17. The mutually parallel axes of rotation of the radial fan 6a and the axial fan 6b are designated 18 and 19, respectively. In the axial fan 6b, its electric motor 10 can be seen with a view of motor electronics 20. The electric motor 10 is arranged in a central, stationary hub 21 with essentially radial support struts 22, which are connected to the fan frame 17 in the region of an opening edge 23 of a flow opening 24. The axial fan 6b can be provided with a cover in the region of the hub 21 or the motor electronics 20.

[0040] A wheel hub 25 of an axial impeller 26 of the axial fan 6b is aligned with the central, stationary hub 21. A number of circumferentially distributed blades or vanes 27 extend in a sickle-shaped and essentially radial manner from the outer circumference of the wheel hub 25. Due to the arrangement of the electric motor 10 in the area of ​​the hubs 21 and 25, the axial size or depth of the axial fan 6b in the direction of its rotational axis 19 is particularly small.

[0041] The radial fan 6b, which is or can be provided with a housing cover (not shown) on the rear, has (on the rear) a motor electronics unit 28. The electric motor 9 and its motor electronics unit 28 are in turn arranged in a central, stationary hub 29 with essentially radial support struts 30, which are connected to the fan frame 17. An axial intake opening 31 of the radial fan 6a directed towards the rear side 7 of the cooler 2 is arranged in Fig. 2visible. The electric motor 9 drives a radial impeller 32 with a number of blades or vanes 33 of the radial fan 6a. In order to achieve the smallest possible axial size, the electric motor 9 is located at least partially, in particular on the rotor side, ie in its design as an external rotor with its rotor, in a wheel hub of the radial impeller 32. The blades or vanes 33 of the radial impeller 32 extend axially in the direction of the axis of rotation 18 and form an outlet opening 34 on the circumference. The axially sucked in cooling air L flows out radially via the outlet opening 32 of the radial fan 6a after being deflected by 90°.

[0042] The Figures 3 and 4show the arrangement of the radial fan 6a and the axial fan 6b axially one behind the other, with the radial fan 6a being arranged in a plane parallel to the rear side 7 and the axial fan 6b being arranged in a plane parallel to the front side 8 of the cooler 2. In the exemplary embodiment, the axes of rotation 18, 19 of the radial and axial fans 6a and 6b are coaxial (same axis). Furthermore, the structure of the radial fan 6a and the axial fan 6b in the embodiment according to the Figures 3 and 4 equal to that after Fig. 2 .

[0043] The motor electronics 20, 28 of the electric motors 9, 10 of the radial fan 6a and the axial fan 6b, respectively, can contain functional modules of the control device 11. The control device 11 can also be fully integrated into the motor electronics 20, 28 of the axial and / or radial fan 6b and 6a, respectively. The control signals SR and SA can thus be generated by the respective motor electronics 20, 28. The electric motors 9, 10 of the two fans 6a, 6b are then connected to the vehicle's electrical system only via supply lines. List of reference symbols

[0044] 1 Radiator / radiator fan system 2 Radiator / heat exchanger 3 Cooling pipe / hose 4 Combustion engine 5 Airflow / air flow direction 6 Fan arrangement 6a Radial fan 6b Axial fan 7 Rear 8 Front 9, 10 Electric motor 11 Control device 12 Electric motor / drive 13 Battery 14 Radial flow arrow 16 Axial flow arrow 17 Fan shroud 18, 19 Rotation axis 20 Motor electronics 21 Hub 22 Strut 23 Opening edge 24 Flow opening 25 Wheel hub 26 Axial impeller 27 Blade / vane 28 Motor electronics 29 Hub 30 Support strut 31 Intake opening 32 Radial fan wheel 33 Blade / vane 34 Outlet opening KKoolant LCooling air SA,R Control signal

Claims

1. Fan assembly (6) for cooling the internal combustion engine (4) of a hybrid vehicle with an electric motor (12) supplied by a rechargeable battery (13) as the electromotive drive, having - a radial fan (6a) which is arranged downstream of a heat exchanger (2), through which a coolant flows, in an airflow direction (5) and axially draws in and radially expels cooling air (L), and an axial fan (6b) which is arranged downstream of the heat exchanger (2) and laterally next to the radial fan (6a) in a plane parallel to the rear side (7) of the heat exchanger or upstream of the heat exchanger (2) in the airflow direction (5) in a plane parallel to the front side (8) of the heat exchanger and axially draws in and axially expels cooling air (L), - wherein a control device (11) is provided and configured to actuate the axial fan (6b) and the radial fan (6a) or only the axial fan (6b) or only the radial fan (6a) to operate as a function of the driving operation or the operating range of the motor vehicle and also to operate the axial fan (6b) and the radial fan (6a) above a specified threshold value of the vehicle speed or the operating range and to operate only the radial fan (6a) below the threshold value during charging operation of the battery (13) for the electromotive drive (12).

2. Fan assembly (6) according to Claim 1, characterized in that the axial fan (6b) and the radial fan (6a) are driven by electric motor.

3. Fan assembly (6) according to Claim 1 or 2, characterized in that the axial fan (6b) and the radial fan (6a), in particular when the axial fan and the radial fan are provided in the same plane downstream of the heat exchanger (2), are arranged in a common fan frame (17).

4. Method for operating a fan assembly (6) according to any of Claims 1 to 3, - in which method the axial fan (6b) and the radial fan (6a) are operated jointly or individually as a function of the operating range and / or the speed of the motor vehicle, - in which method the axial fan (6b) and the radial fan (6a) are operated above a specified threshold value of the vehicle speed or the operating range, and - in which method only the radial fan (6a) is operated below the threshold value during charging operation of the battery (13).

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