Controllable radial fan for an electric machine

Abstract

The invention provides a controllable radial fan (1) for an electric machine, which comprises a rigid fan wheel (2) with a rigid fan disk (2a) and several rigid fan blades (2b) as well as a fan control (3) with a control slide (3a) and a slide actuation (3b), wherein the control slide (3a) is mounted axially displaceable relative to the fan wheel (2) and is connected to the slide actuation (3b), so that a cooling airflow (4) flowing through the spaces between the fan blades (2b) can be controlled by a displacement of the control slide (3a) along the axis of rotation (1a).

Description

Technical field

[0001] The present invention relates to a controllable radial fan for an electric machine, by means of which the air cooling of the electric machine is optimized during operation. State of the art

[0002] Electric machines have a fan on the rotor to cool the windings on the stator, primarily in the area of ​​the winding heads. Especially at low speeds and high electrical currents required to generate high torques, the electric machine has a high cooling demand, which the fan must meet. However, as the speed of the electric machine increases, the aerodynamic drag caused by the fan rises disproportionately to the cooling demand of the winding heads. The fan is preferably a radial fan. An electric motor drives the fan wheel, drawing in cooling air axially, i.e., along the axis of rotation. The rotation of the fan wheel deflects this air and accelerates it radially outwards.

[0003] From patent application CN 113357154 A, a centrifugal pump with an electric motor is known, which has a switchable heat dissipation mechanism on its end face. The mechanism comprises a fan cover that is automatically actuated depending on the motor temperature. When cold, the fan cover is closed to protect against contamination and opens when the motor heats up. The fan cover is arranged axially in front of the fan and is actuated by rotating a cover disc about the axis of rotation of the fan relative to a fan disk.

[0004] Patent application CN 115566846 A discloses an electric motor with a self-actuated fan baffle, wherein spring-loaded slides are moved radially outwards by the resulting centrifugal force due to increasing speed of the electric motor.

[0005] German patent application DE 2 049 679 A1 discloses a fan for an electric machine whose blades are elastically designed so that they bend radially outwards with increasing rotational speed due to centrifugal force, thus reducing the ventilation throughput. This is intended to optimize the drive power.

[0006] German patent application DE 44 34 598 A1 discloses a radial fan for electric machines with fan blades actuated by centrifugal force as the speed of the electric machine increases. The fan blades are designed such that flexible areas of the blades deform, thus completely closing the gap to the circumferentially adjacent fan blade and completely interrupting the airflow.

[0007] German patent application DE 101 55 224 A1 discloses a fan wheel for electric machines, which has a fan disk with radially outwardly directed and annularly distributed fan blades. As the rotational speed increases, an inner end section of the fan blade is increasingly pivoted radially outward, thereby reducing its cross-section relative to the adjacent fan blade.

[0008] German patent application DE 44 46 345 A1 relates to a rotary fan for generating an airflow for cooling an AC generator. The fan has rigid fan blades which are rotatably mounted on a base plate on support bolts and are spring-loaded. Due to the increasing centrifugal force at higher rotational speeds, the fan blades are automatically adjusted to reduce the cooling airflow.

[0009] From German patent application WO 1991 005 397 A1, a radial fan for an electric motor is known, which has an impeller with several rigid fan blades arranged on the impeller. Each blade is rotatably arranged about an axis of rotation that is substantially parallel to the axis of rotation of the fan. The blades are arranged such that the centrifugal force on the blade caused by the rotation of the fan aims to rotate the blade about the axis of rotation in such a way as to reduce the angle of attack of the blade, with spring elements counteracting the rotation of the blade. Alternatively, the blades are connected to a rotary disk for their uniform adjustment.

[0010] The patent application WO 2023 046 831 A1 relates to a radiator-fan system with a radiator bulkhead for closing the radiator-fan system. The radiator bulkhead has bulkhead plates arranged radially around a central axis, which are pivotable about a pivot axis normal to the central axis. Object of the invention

[0011] The object of the invention is to provide an improved radial fan for an electric machine. Solution to the task

[0012] The problem is solved by a controllable radial fan with advantageous fan control for an electric machine according to the features of claim 1. Advantageous further developments are described in the dependent claims and the exemplary embodiments. Description of the invention

[0013] The invention provides a controllable radial fan with an advantageous fan control system for an electric machine, which allows for a simple reduction in the radial fan's effectiveness with increasing rotational speed to reduce aerodynamic drag. The radial fan comprises a fan wheel with a fan disc and several fan blades, as well as a fan control system with a control slide and a slide actuation mechanism.

[0014] The fan control system adjusts the airflow delivered by the radial fan to the cooling requirements of an electric motor. Specifically, as the radial fan speed increases, the fan control system gradually throttles the airflow, thus reducing an oversupply of air for cooling the electric motor and consequently reducing the aerodynamic drag of the radial fan compared to an uncontrolled radial fan. Throttle control refers to the reduction of the effective cross-sectional area for the cooling airflow through the radial fan. This has a positive effect on the effective efficiency of the electric motor.

[0015] The fan wheel is designed as a primarily rigid fan wheel, with rigid fan blades immovably connected to the rigid fan disc. The fan blades are arranged in the manner of a radial fan, so that when the radial fan is operating, a cooling airflow is generated radiating outwards from the fan's axis of rotation. Furthermore, the fan blades are arranged rotationally symmetrically around the radial fan's axis of rotation. Each fan blade has a radially inner inlet edge and a radially outer outlet edge spaced according to the blade's length. The spaces between the fan blades form an inlet area in the region of the inlet edges and an outlet area in the region of the outlet edges.Furthermore, the fan blades can be connected to each other by a cover plate, so that a continuous channel for the cooling airflow from the inlet surface to the outlet surface is formed between two adjacent fan blades, the fan disc and the cover plate.

[0016] The control slide is mounted so that it can be axially displaced relative to the fan wheel and is connected to the slide actuator. This actuator moves the control slide axially along the axis of rotation relative to the fan wheel during operation of the radial fan, thus controlling the flow of cooling air through the spaces between the fan blades. The actuator allows the control slide to be moved between a first position and a second position. In the first position, the cooling air flow through the spaces between the fan blades is unrestricted, and in the second position, the cooling air flow is restricted.

[0017] The control slide is designed as an orifice for controlling the cooling airflow, by means of which the effective flow cross-section in the area of ​​the inlet surface and / or in the area of ​​the outlet surface can be changed, whereby the effective flow cross-section is reduced by the space between the fan blades in the second position of the control slide compared to the first position of the control slide.

[0018] The control valve is advantageously designed as a simple tube valve, positioned radially inside the fan blades and axially displaceable along the radial fan's axis of rotation. Actuation of the control valve, designed as an internal tube valve, controls the effective flow cross-section in the inlet area. In the second position of the control valve, the inlet area is at least partially covered by the control valve. The reduction of the effective flow cross-section is thus achieved by a cylindrical outer surface.

[0019] Alternatively, the control valve is advantageously designed as a simple tube valve, wherein the tube valve is arranged radially outside the fan blades and axially displaceable along the axis of rotation of the radial fan. Actuation of the control valve, designed as an external tube valve, controls the effective flow cross-section in the area of ​​the discharge surface, with the control valve at least partially covering the discharge surface in its second position. The reduction of the effective flow cross-section is thus achieved by a cylindrical outer surface.

[0020] Alternatively, the control valve is designed as a U-ring valve, in which the U-ring valve encloses the fan blades like a hood and is axially displaceable along the axis of rotation of the radial fan. The U-ring valve thus comprises a radially inner and a radially outer tube valve, which are combined like a hood. The opening of the U-ring valve is oriented towards the fan blades, so that in the second position of the control valve, the fan blades are at least partially located within the interior of the U-profile of the U-ring valve. Actuation of the control valve, designed as a U-ring valve, controls the effective flow cross-section in the area of ​​the inlet and outlet surfaces.

[0021] Alternatively, the control valve is designed as a conical valve, positioned radially inside the fan blades and axially displaceable along the radial fan's axis of rotation. Actuation of the internally mounted conical control valve controls the effective flow cross-section in the inlet area, with the control valve at least partially covering the inlet area in its second position. The reduction of the effective flow cross-section is thus achieved by a conical outer surface.

[0022] The control slide also has at least one frame by means of which the axially displaceable mounting of the control slide relative to the fan wheel is ensured. The frame, through which the cooling air flows, is advantageously designed as a grid, perforated plate, or star-shaped rod assembly oriented perpendicular to the axis of rotation.

[0023] The valve actuation is designed as a centrifugal drive, utilizing centrifugal weights and a crank mechanism to achieve axial displacement of the control valve depending on the fan wheel's rotational speed. The valve actuation is operatively connected to the fan wheel, so that as the fan wheel's rotational speed increases, the centrifugal weights cause the control valve to shift from its first position towards its second. The centrifugal drive is therefore rotationally fixed to the fan wheel. The fan wheel also features a bearing that allows the control valve to be axially displaceable from the fan wheel.

[0024] Alternatively, the slide actuation is implemented as an electromechanical actuator. Using centrifugal weights and a crankshaft drive, an axial displacement of the control slide can be achieved depending on the rotational speed of the fan wheel. The slide actuation is operatively connected to the fan wheel, so that as the rotational speed of the fan wheel increases, the centrifugal weights cause a displacement of the control slide from the first position towards the second position.

[0025] Alternatively, the slide actuation is implemented as a hydraulic actuator, whereby centrifugal weights and a hydraulic system allow for axial displacement of the control slide depending on the rotational speed of the fan wheel.

[0026] A return spring, which counteracts the displacement caused by the slide actuation, enables the control slide to return to its original position.

[0027] For the use of the radial fan to cool an electric machine, the fan wheel is connected to a machine shaft and therefore to a rotor of the electric machine, so that the fan wheel rotates with the rotor when the electric machine is operated. Examples of implementation

[0028] An exemplary first embodiment of a controllable radial fan 1 according to the invention for an electric machine is shown here. The accompanying figures show: Fig. 1 a schematic representation of the controllable radial fan 1 in the unthrottled state and Fig. 2 a schematic representation of the controllable radial fan 1 in the throttled state.

[0029] The first embodiment of the controllable radial fan 1, which is advantageous according to the invention, is shown in Fig. 1 and Fig. Figure 2 features a rigid fan wheel 2 with a rigid fan disc 2a and several rigid fan blades 2b, as well as a fan controller 3 with a control slide 3a and a slide actuation 3b. The fan controller 3 throttles the cooling airflow 4 delivered by the radial fan 1 by reducing the effective flow cross-section 5, as shown in Figure 2. Fig. 2.

[0030] The fan blades 2b are arranged rotationally symmetrically about an axis of rotation 1a of the radial fan 1. Each fan blade 2b has a radially inner inlet edge 2c and a radially outer outlet edge 2d spaced apart according to the length of the fan blade 2b. The spaces between the fan blades 2b form an inlet surface 2e in the region of the inlet edges 2c and an outlet surface 2f in the region of the outlet edges 2d. Furthermore, the fan blades 2b are connected to each other by a cover plate 2g, so that a continuous channel from inlet surface 2e to outlet surface 2f is formed in the space between two adjacent fan blades 2b and between the fan plate 2a and the cover plate 2g.

[0031] The control slide 3a is mounted to be axially displaceable relative to the fan wheel 2 and is connected to the slide actuation 3b, so that by moving the control slide 3a along the axis of rotation 1a, the cooling airflow 4 flowing through the spaces between the fan blades 2b is controlled. The control slide 3a can be moved between a first position with an unrestricted cooling airflow 4, as shown in the figure, by means of the slide actuation 3b. Fig. 1, and a second position with throttled cooling airflow 4, shown in Fig. 2, movable.

[0032] The control slide 3a is partially designed as a simple tube slide and is radially internal to the fan blades 2b and axially displaceable along the axis of rotation 1a of the radial fan 1, whereby control of the effective flow cross-section 5 in the area of ​​the inlet surface 2e takes place, as shown in Fig. 2. The reduction of the effective flow cross-section 5 is therefore achieved by a cylindrical outer surface. The control valve 3a, designed as a tube valve, also has at least one frame 3c, by means of which the axially displaceable mounting of the control valve 3a relative to the fan wheel 2 is ensured. The frame 3c is formed by a perforated plate oriented perpendicular to the axis of rotation 1a, by means of which the tube valve is connected to the mounting.

[0033] The valve actuation 3b is designed as a centrifugal drive and comprises several centrifugal weights 3d and several crank mechanisms 3e for axial displacement of the control valve 3a. The valve actuation 3b is operatively connected to the fan wheel 2, such that the centrifugal weights 3d cause the control valve 3a to shift from the first position towards the second position as the rotational speed of the fan wheel 2 increases. A return spring 3f, which counteracts the displacement caused by the centrifugal weights 3d, allows the control valve 3a to return to its original position.

[0034] A second embodiment of a controllable radial fan 1 according to the invention for an electric machine is shown here by way of example. The accompanying figures show: Fig. 3 a schematic representation of the controllable radial fan 1 in its unthrottled state and Fig. 4 a schematic representation of the controllable radial fan 1 in the throttled state.

[0035] Compared to the first embodiment of a controllable radial fan 1 according to the invention for an electric machine, the control slide 3a in the second embodiment is designed as a pipe slide located radially outside the fan blades 2b and axially displaceable along the axis of rotation 1a of the radial fan 1, as shown in Fig. 3 and Fig. 4. By actuating the control slide 3a, the effective flow cross-section 5 in the area of ​​the outlet surface 2f is controlled, whereby in the second position of the control slide 3a the outlet surface 2f is at least partially covered by the control slide 3a, as shown in Fig. 4. The reduction of the effective flow cross-section 5 is therefore achieved by a cylindrical outer surface. The frame 3c is formed by a grid oriented perpendicular to the axis of rotation 1a, by means of which the pipe valve is connected to the bearing.

[0036] A third embodiment of a controllable radial fan 1 according to the invention for an electric machine is shown here by way of example. The accompanying figures show: Fig. 5 a schematic representation of the controllable radial fan 1 in the unthrottled state and Fig. 6 a schematic representation of the controllable radial fan 1 in the throttled state.

[0037] Compared to the first embodiment of a controllable radial fan 1 according to the invention for an electric machine, the control slide 3a in the third embodiment is designed as a U-ring slide, wherein the U-ring slide encloses the fan blades 2b in the sense of a hood, as shown in Fig. 5 and Fig. 6. The opening of the U-ring slide is oriented towards the fan blades 2b, so that the fan blades 2 are at least partially located in the interior of the U-profile of the U-ring slide in the second position of the control slide 3a, as shown in Fig. 6. By actuating the control valve 3a, which is designed as a U-ring valve, the effective flow cross-section 5 in the area of ​​the inlet area 2e and the outlet area 2f is controlled.

[0038] The slide actuation 3b is designed as an electromechanical actuator, whereby an axial displacement of the control slide 3a can occur independently of the rotational speed of the fan wheel 2. The slide actuation 3b is not operatively connected to the fan wheel 2, but to a housing 6, for example, the housing 6 of the electric machine, so that a displacement of the control slide 3a can occur from the first position towards the second position.

[0039] A fourth embodiment of a controllable radial fan 1 according to the invention for an electric machine is shown here by way of example. The accompanying figures show: Fig. 7 a schematic representation of the controllable radial fan 1 in the unthrottled state and Fig. Figure 8 shows a schematic representation of the controllable radial fan 1 in its throttled state.

[0040] Compared to the first embodiment of a controllable radial fan 1 according to the invention for an electric machine, the control slide 3a in the fourth embodiment is designed as a conical slide, as shown in Fig. 7 and Fig. 8. The reduction of the effective flow cross-section 5 is therefore achieved by a conical surface, as shown in Fig. 6. By actuating the control valve 3a, which is designed as a conical valve, the effective flow cross-section in the area of ​​the inlet surface 2e is controlled.

[0041] The slide actuation 3b is designed as an electromechanical actuator, whereby an axial displacement of the control slide 3a can occur independently of the rotational speed of the fan wheel 2. The slide actuation 3b is not operatively connected to the fan wheel 2, but to a housing 6, for example, the housing 6 of the electric machine, so that a displacement of the control slide 3a can occur from the first position towards the second position. List of reference symbols used 1 radial fan 1a Rotary axis 2 fan wheels 2a Fan disc 2b Fan blades 2c Inlet edge 2d Outflow edge 2e Inlet area 2f Outflow area 2g cover plate 3 Fan controller 3a Control valve 3b Slider operation 3c frame 3D centrifugal weights 3e Push-crank gear 3f Return spring 4 Cooling airflow 5 Flow cross-section 6 cases QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] CN 113357154 A

[0003] CN 115566846 A

[0004] DE 2 049 679 A1

[0005] DE 44 34 598 A1

[0006] DE 101 55 224 A1

[0007] DE 44 46 345 A1

[0008] WO 1991 005 397 A1

[0009] WO 2023 046 831 A1

[0010]

Claims

Controllable radial fan (1) for an electric machine comprising a rigid fan wheel (2) with a rigid fan disk (2a) and several rigid fan blades (2b) and a fan control (3) with a control slide (3a) and a slide actuation (3b), wherein the control slide (3a) is mounted axially displaceable relative to the fan wheel (2) and is connected to the slide actuation (3b), so that a cooling airflow (4) flowing through the spaces between the fan blades (2b) can be controlled by a displacement of the control slide (3a) along the axis of rotation (1a). Controllable radial fan (1) according to claim 1, characterized in that the fan blades (2b) each have a radially inner inlet edge (2c) and a radially outer outlet edge (2d) spaced apart according to the length of the fan blade (2b), wherein the spaces between the fan blades (2b) form an inlet area (2e) in the region of the inlet edges (2c) and an outlet area (2f) in the region of the outlet edges (2d), so that the effective flow cross-section (5) is controlled in the region of the inlet area (2e) and / or outlet area (2f). Controllable radial fan (1) according to one of the preceding claims, characterized in that the slide actuation (3b) is designed as a centrifugal drive, so that a displacement of the control slide (3a) from the first position towards the second position can take place. Controllable radial fan (1) according to one of the preceding claims, characterized in that the control slide (3a) is designed as a U-ring slide.

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