Hybrid group for rotationally driving cooling FANS of vehicles combusion engines

Abstract

Hybrid group for rotationally driving fans (1) of vehicle engines, comprising an electromechanical coupling (40) for taking up the movement from the crankshaft of the vehicle and an electric motor (10) which can be powered independently of the combustion engine, respectively connected to the driven shaft (2) which drives the fan (1), the group being characterized in that the electric motor (10) is arranged upstream of the electromechanical coupling (40) in the axial direction (X-X) and is integral with a bell member (5) fastened to the base (3) of the combustion engine.

Description

[0001] HYBRID GROUP FOR ROTATIONALLY DRIVING COOLING FANS OF VEHICLES COMBUSION ENGINES

[0002] DESCRIPTION

[0003] The present invention relates to a hybrid group for rotationally driving cooling fans of vehicle combustion engines and a fan equipped with such a hybrid driving group.

[0004] It is known, in the technical sector relating to the cooling of the coolants contained in the radiators of motor vehicles, that there exists the need to force air onto the said radiator, in order to obtain as rapid as possible dissipation of heat from the liquid externally, said forced air flow being obtained by causing the rotation of a fan, normally mounted either directly on the crankshaft, or on the shaft of the water pump, or on a fixed driven shaft carrying a pulley which receives movement from a belt driven by the crankshaft.

[0005] It is also known that said fan must be rotated only upon reaching a certain predefined water temperature detected by means of a thermostat which operates an electromagnetic clutch, closing of which causes the rotation of the fan. For this it is required that the fan should be able to rotate:

[0006] - at a lower speed than that of the drive shaft for cooling in low temperature conditions externally and / or of the coolant;

[0007] - at a speed the same as or even greater than that of the drive shaft at higher temperatures externally or therefore of the coolant or during use in severe conditions which result in overheating of the engine;

[0008] - at zero speed, namely with the fan which remains in the idle condition with respect to the drive shaft, in the case of particularly low temperatures at which further cooling is not useful or is even damaging.

[0009] US2021 / 079832 and EP 3,638,895 disclose hybrid groups for driving fans of combustion engines and describe the presence of an electric motor arranged immediately upstream of the fan to be rotated and downstream of the electromechanical coupling for connection to the crankshaft; these solutions do not allow the installation of sufficiently powerful electric motors necessary for the large amount of air which must be forced onto the radiators in particular in large size vehicles such as articulated lorries, while maintaining however small axial dimensions of the assembly.

[0010] The technical problem which is posed therefore is that of providing a device for transmitting the rotational movement to a fan for cooling the coolant of motor vehicles, which is able to cause the rotation of the fan at a controllable and adjustable number of rpms depending on the actual cooling requirement of the engine.

[0011] In connection with this problem a further requirement is that the device should have compact dimensions, in particular in the axial direction, and that it should be able to be controlled by means of direct detection of the temperature of the coolant.

[0012] In connection with this problem it is also required that this device should be able to provide reliable operation which ensures rotation of the fan also in the event of a malfunction of the electric control and operating circuit and should have small radial and / or axial dimensions, but at the same time should be able to produce high torques also at a slow speed of rotation of the engine, so as to be applicable also to high performance fans of heavy vehicles with a low-speed engine, or rotation of the fan at a slow speed in conditions where the combustion engine is operating at a high speed.

[0013] It is also required the device should be easy and inexpensive to produce and assemble and be able to be easily installed in the engine compartment without the need for special adaptation.

[0014] These results are obtained according to the present invention by an operating group for cooling fans of combustion engines, in particular of vehicles, according to the characteristic features of Claim 1 .

[0015] The present invention relates furthermore to an assembly consisting of a hybrid group for rotationally driving fans of vehicle engines and a cooling fan for vehicle engines according to the characteristic features of Claim 9.

[0016] Further details may be obtained from the following description of a nonlimiting example of embodiment of the subject of the present invention provided with reference to the attached drawings in which:

[0017] Figure 1 : shows a schematic axially sectioned view of a first example of embodiment of the device according to the invention;

[0018] Figure 2: shows a schematic axially sectioned view of a second example of embodiment the device according to the invention; and

[0019] Figure 3: shows a schematic axially sectioned view of a third example of embodiment the device according to the invention.

[0020] As shown in Fig. 1 and assuming solely for the purpose of simpler description a longitudinal direction X-X coinciding with the axis of rotation of the fan; a downstream part “V” corresponding to the fan side and an upstream part “M”, opposite to the preceding side, the operating group for providing the movement of a motor vehicle cooling fan 1 , which is mounted on a shaped disc 1a provided with a coaxial through-hole 1 b, i.e. a driving group according to the invention, below also called hybrid group since it comprises a electromechanical operating system and a electrical operating system, comprises:

[0021] - a bell-shaped member 5 which is fastened to the base 3 of the vehicle combustion engine and which has, integral therewith, the stator 11 of an electric motor 10, the rotor 13 of which caries the magnets and is provided with a coaxial hole 13a suitable for coupling with a first upstream end 2a of a coaxial shaft 2, the other downstream end 2b of which is coupled with the hole 1 b in the disc 1 a for holding the fan 1 .

[0022] The central part of the shaft 2 is supported by a multi-level bearing 20 or forms part of a multi-level bearing 20 - the intermediate race 20b of which is fastened to the bell member 5 and the radially outer race 20c of which supports a rotor 30, the external circumference of which is shaped as a pulley 30a suitable for coupling with a belt 31 for taking up the movement from the crankshaft (not shown) of the vehicle.

[0023] The rotor 30 has an internal cavity 30b which is open in the upstream direction and which has, housed inside it, an electromagnet 41 which forms part of an electromagnetic coupling 40.

[0024] The electromagnetic coupling 40 comprises an armature 42 fastened, by means of an elastic plate 42, to the fan-holder disc 1a; with this configuration the armature is rotationally locked, but displaceable towards the rotor 30 following the energization of the electromagnet and, vice versa, able to return into the position detached from the latter, when subject to the elastic recall force of the plate 42a.

[0025] Fig. 2 shows a second embodiment of the hybrid system for driving a vehicle fan, in the description of which below different reference numbers are used to indicate only the modified parts, while the same reference numbers are maintained for the parts which are common to both solutions.

[0026] In detail: the bell member 105 has an axial extension 105a, on the outer surface 105a of which a first bearing 121 supporting the rotor 30 is keyed, while the inner surface of the same axial extension 105a has, fixed thereon, the outer race 122a of a second bearing 122, the inner race 122b of which is keyed onto the driven shaft 2 which drives the fan 1 .

[0027] With this embodiment it is possible to use a bearing for supporting the large- size rotor since it is supported by the bell member integral with the engine base, and a small-size bearing for the driven shaft alone which is no longer acted on by the belt pulling force which is transmitted entirely onto the first outer bearing.

[0028] Fig. 3 shows a third embodiment of the fan driving system where the bearing supporting the shaft 2 according to the preceding version is replaced with two bearings supporting the driven shaft, i.e.: a first downstream bearing 201 with outer race 201 a fastened to the inner surface of the axial extension 105a of the bell member 105; and a second upstream bearing 202 mounted on a fixed flange 200 arranged between the bell member 105 and the base 3 of the engine to which it is respectively fastened.

[0029] With this solution it is possible to use even smaller size bearings since fastening of the upstream bearing to the base further reduces the load acting on the projecting part of the driven shaft and therefore on the downstream bearing.

[0030] With all the embodiments described and shown it is possible to implement the following fan operating modes:

[0031] -) in conditions where the electromagnet 41 is energized, the induced magnetic field overcomes the elastic resistance of the plate 42a, axially recalling the armature 42 with the consequent engagement thereof with the rotor 30 and operation of the shaft 2 at a speed determined by the combustion engine via the belt 31 and the pulley 30a;

[0032] -) in conditions where the electromagnetic 41 is de-energized, the armature is recalled by the elastic plate axially away from the electromagnet 41 , releasing the rotor 30 from the armature 42 and therefore from the shaft 2 of the fan which remains idle;

[0033] -) if, in the idle condition of the shaft 2, a rotation of the fan 1 at a speed independent of that determined by the combustion engine is required, the electric motor 10 is powered so that the movement of its rotor 32 causes the rotation of the shaft 2 at the desired speed of rotation able to determine the supply of air to the radiator which is actually needed.

[0034] It is therefore clear how with the hybrid group for driving a vehicle fan it is possible to obtain all the speeds necessary or sufficient for the various required operating conditions such as:

[0035] - a speed lower than that of the drive shaft for cooling in low temperature conditions of the coolant;

[0036] - a speed the same as or even greater than that of the drive shaft at higher temperatures of the coolant or during use in severe conditions which result in overheating of the engine;

[0037] - at zero speed, namely with the fan which remains in the idle condition with respect to the drive shaft, in the case of particularly low temperatures at which further cooling is not useful or is even damaging.

[0038] It is also possible to operate the fan even when the combustion engine is switched off in order to avoid typical situations which affect the aforementioned engines such as sudden overheating.

[0039] In addition to the above and taking into account the high mass of air which the fan forces towards the radiator and the consequent high power absorbed by the fan itself, particularly for large vehicles such as articulated lorries, and the consequent need for a necessarily suitably powerful electric motor capable of outputting at least 3-4 kW, and therefore with a large size and weight, the described configurations which keep the electric motor anchored to the base of the combustion engine, ensuring its stability, and the electromagnetic coupling downstream of the electric motor, interposed between the latter and the fan, allow adequate sizing, while maintaining a positive reduction in the radial and / or axial dimensions of the group and / or a reduction in the radial stresses exerted on the driven shaft whose length is conditioned by the axial position of the fan which, being external to the radiator containing the fluid to be cooled, is normally very distant from the engine base.

[0040] With the improved configuration of the hybrid group, the weight of the electric motor is borne by the base, therefore allowing the weight and power to be increased depending on the different conditions of use.

[0041] The hybrid group according to the invention is also able to provide reliable operation which ensures rotation of the fan also in the case of malfunctioning of one of the two electrical / electromechanical control circuits, said malfunctioning being compensated for by the intervention of the other electromechanical control and operating circuit.

[0042] Although described in connection with a number of embodiments and a number of preferred examples of implementation of the invention, it is understood that the scope of protection of the present patent is determined solely by the claims below.

Claims

CLAIMS1. Hybrid group for rotationally driving a driven shaft (2) supporting fans (1) of vehicle engines, the group comprising an electromechanical coupling (40) comprising a rotor (30) which has an external circumference shaped as a pulley (30a) designed to take up the movement from the crankshaft of the vehicle, for driving the driven shaft (2), and an internal cavity (30b), open in the upstream direction; and an electric motor (10) which can be powered independently of the combustion engine, in turn connected to the driven shaft (2) which drives the fan (1), the group being characterized in that the electric motor (10) is arranged upstream of the electromechanical coupling (40) in the axial direction (X-X) and its stator (11 ) is integral with a bell member (5) fastened to the base (3) of the combustion engine.

2. Group according to Claim 1 , characterized in that the fan (1 ) is mounted on a disc (1a) provided with a coaxial hole (1 b) for coupling with a downstream end (2b) of the driven shaft (2).

3. Group according to the preceding claims, characterized in that the rotor (13) of the electric motor (10) carries the magnets (12) and is provided with a coaxial hole (13a) suitable for coupling with an upstream end (2a) of the driven shaft (2).

4. Group according to the preceding claims, characterized in that the driven shaft (2) is mounted on / forms part of a multi-level bearing (20).

5. Group according to the preceding claims, characterized in that said multi-level bearing comprises a radially intermediate race (20b) fastened to the bell member (5) and a radially outer race (20c) on which the rotor (30) of the electromechanical coupling is mounted.

6. Group according to Claim 1 , characterized in that the electromechanical coupling comprises an electromagnet (41) housed inside the cavity (30b) of the rotor (40), and an armature (42) fastened, by means of an elastic plate (42a), to the fan-holder disc (1 a).

7. Group according to Claim 1 , characterized in that the bell member (105) has an axial extension (105a), the radially outer surface of which has, keyed thereon, a first bearing (121) which supports the rotor (30), the radially inner surface of the said axial extension (105a) having, fixed thereon, the radially outer race (122a) of a second bearing (122), the radially inner race (122b) of which is keyed onto the driven shaft (2) for driving the fan (1).

8. Group according to Claim 7, characterized in that it comprises two bearings supporting the driven shaft, i.e.: a first downstream bearing (201) with outer race (201 a) fastened to the inner surface of the axial extension (105a) of the bell member (105); and a second upstream bearing (202) mounted on a fixed flange (20) arranged between the bell member (105) and the base (3) of the engine to which it is respectively fastened.

9. Assembly comprising a hybrid group for rotationally driving fans (1 ) of vehicle engines according to Claim 1 and a fan (1) for cooling vehicle engines.

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