IN-WHEEL MOTOR AND VEHICLE

Abstract

The invention relates to an in-wheel motor (100) comprising a rotor (110A, 110B) coaxially surrounding a stator (102), the stator comprising electromagnets (104), the electromagnets in working producing heat, the heat at least in part removed from the stator by gas, characterized in that the motor comprises an electric fan (150) internal to the rotor for displacing the gas.

Claims

1. An in-wheel motor comprising a rotor coaxially surrounding a stator, the stator comprising electromagnets, the electromagnets in working producing heat, the heat at least in part removed from the stator by gas, wherein the motor comprises an electric fan internal to the rotor for displacing the gas.

2. The in-wheel motor of claim 1 in which the motor comprises a temperature sensor and a controller attached thereto, the controller controlling the fan in such a way that the amount of gas that is displaced by the fan depends on the temperature of the stator.

3. The in-wheel motor of claim 1 in which the fan is disabled if the temperature of the stator is below a predetermined temperature and enabled if the temperature is above the predetermined temperature.

4. The in-wheel motor of claim 1 in which the gas has a heat capacity higher than that of dry air at one atmosphere.

5. The in-wheel motor of claim 4 in which the gas is pressurized air.

6. The in-wheel motor of claim 5, comprising an air valve arranged to provide the pressurized air from outside the in-wheel motor to an inner space enclosed by the rotor.

7. The in-wheel motor of claim 4, comprising a conduit arranged to transfer water from outside the in-wheel motor to an inner space enclosed by the rotor.

8. The in-wheel motor of claim 7, comprising a nozzle arranged at an end of the conduit in the inner space enclosed by the rotor, wherein the nozzle is adapted to vaporize water entering the inner space.

9. The in-wheel motor of claim 1 in which the electric fan is mounted in a through-hole in the stator.

10. The in-wheel motor of claim 1, wherein the stator has a through-hole extending in an axial direction of the in-wheel motor, wherein the electric fan is arranged to displace the gas through the through-hole.

11. The in-wheel motor of claim 9, comprising a guiding element, wherein the rotor comprises a rotor surface, wherein the guiding element is arranged on the rotor surface, wherein the electric fan is arranged radially inward of the electromagnets, wherein the electric fan is arranged to displace the gas towards the rotor surface, wherein the guiding element is adapted to divide the gas into a radially inward flow and a radially outward flow.

12. The in-wheel motor of claim 1, comprising at least one fin, wherein the rotor comprises a rotor surface, wherein the at least one fin is arranged on the rotor surface, wherein the electric fan is arranged to displace the gas along the at least one fin.

13. The in-wheel motor of claim 12, wherein the at least one fin is spiral shaped.

14. A vehicle equipped with one or more in-wheel motors according to claim 1.

15. The vehicle according to claim 14, wherein the in-wheel motor comprises a conduit, wherein the vehicle comprises a HVAC-unit, wherein the HVAC-unit is adapted to extract water from air, and wherein the HVAC-unit is adapted to provide the extracted water via the conduit to the in-wheel motor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] The invention is now elucidated using figures, in which identical reference signs indicate corresponding features. To that end:

[0048] FIG. 1 schematically shows a cross-section of the motor according to the invention.

[0049] FIG. 2 schematically shows a cross-section of the motor according to a second embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0050] FIG. 1 schematically shows a cross-section of the motor according to the invention.

[0051] The in-wheel motor 100 shows a stator 102 with electromagnets 104. An axle 106 is fixedly connected to the stator. A rotor 110A/110B coaxially surrounding the stator 102 encloses an inner volume 112 where the stator 102 resides. The rotor 110 comprises a multitude of permanent magnets 116. The motor 100 comprises a wheel bearing 120 radially positioned between the rotor 110 and the axle 106 and axially positioned between the stator 102 and the end of the axle 106 sticking out of the motor 100. One or more electric conductors 114 pass through a bore 108 in the axle 106 to the inner volume 112. The electric conductors 114 feed power to the electromagnets 116. The wheel rim 122 is for carrying a tyre 124 is removably connected to the rotor 110. On the rotor a disk 126 of a brake disk is mounted to enable (mechanical) breaking.

[0052] In a circular through-hole in the stator 104 an electric fan 150 is mounted. In working the electric fan 150 forces air (gas) to pass through the stator 102, to the perimeter of the stator 102, through the magnetic gap 118 between permanent magnets 116 and electromagnets 104 back towards the inlet of the fan 150. The flow of the gas 160 is indicated by the arrows. The electric fan 150 is arranged internally to the rotor 110 and displaces the gas 160 through the inner space 112 as indicated by the arrows.

[0053] By applying a three-phase electric signal to the electromagnets 104, a rotating magnetic field is generated. The interaction of the rotating magnetic field together with the magnetic field of the permanent magnets 116 causes a torque between rotor 110 and stator 102. This torque is then transferred to the road and causes propulsion for the vehicle. Efficiency of such a motor is well above 90%, that is: in normal use less than 10% of the applied electric power is dissipated in heat, and most of it is transferred in mechanic power used for propulsion (to accelerate the vehicle, to overcome roll resistance, to overcome aerodynamical drag, etc). Therefore, the amount of heat that is dissipated is limited.

[0054] A major contributor for transport of the heat from stator 102 to rotor 110 is due to the thermal capacitance of the gas between stator 102 and rotor 110. Especially if the gas 160 is moving at high speed, and in a turbulent fashion, this transport becomes high. In part this is already caused by the relative movement of rotor 110 and stator 102, especially if one or both are equipped with a multitude of small dimples or projections. The fan 150 can be seen as an efficient turbulent air mixer, homogenising the air inside the motor chamber, i.e., the inner space 112. The more severe the mixing, the higher the heat transfer from stator 102 to rotor 110.

[0055] As shown by the arrows, the electric fan 150 displaces the gas along parts 110A and 110B of the rotor, and through the magnetic gaps 118. Heat generated by the electromagnets 104 during operational use is transferred from the electromagnets 104 to the gas 160 in the magnetic gap 118. The heated gas is then displaced along the rotor 110, causing the heat to be transferred from the heated gas 160 to the rotor 110. The rotor 110 transfers the heat to the outside environment.

[0056] The power for the electric fan 150 is fed into the rotor 110 through the same bore(s) that carry the electric conductors 114 that feed the electromagnets, i.e., bore 108. As an alternative the power can be derived from the star- or wye point of the three-phase connection.

[0057] The fan 150 can be controlled for high or low air displacement (speed), according to the temperature of the stator 102. Also, the fan 150 can be kept active (cooling) after the vehicle is parked, until the stator 102 is below a pre-set temperature.

[0058] A simple solution is to power the fan 150 via a bi-metal switch (a clixon) or the like.

[0059] A second embodiment according to the invention is depicted in FIG. 2. The second embodiment has the same features as the embodiment of FIG. 1, except for the following.

[0060] The in-wheel motor 200 comprises a temperature sensor 216 and a controller 202 attached thereto. The controller 202 is adapted to control the fan 150 in such a way that the amount of gas 160 that is displaced by the electric fan 150 depends on the temperature of the stator 102.

[0061] The electric fan 150 is, for example, disabled if the temperature of the stator 102 is below a predetermined temperature and enabled if the temperature is above the predetermined temperature.

[0062] The gas 160 has a heat capacity higher than that of dry air at one atmosphere. The gas 160 is pressurized air. The in-wheel motor 200 comprises an air valve 204 arranged to provide the pressurized air from outside the in-wheel motor 200 to the inner space 112 enclosed by the rotor 110.

[0063] The in-wheel motor 200 comprises a conduit 206 arranged to transfer water from outside the in-wheel motor 200 to the inner space 112 enclosed by the rotor 110. A nozzle 208 is arranged at the end of the conduit 206 in the inner space 112. The nozzle 208 is adapted to vaporize water entering the inner space 112. The conduit 206 is connected to the HVAC-unit of the vehicle. The HVAC-unit extracts water from air and provides the water through the conduit 206. The controller 202 controls the amount of water that is provided through the conduit 206, for example, by controlling a valve in the conduit 206.

[0064] The stator 102 has a through hole 210 extending in an axial direction of the in-wheel motor 200. The axial direction is in the x-direction. The axial direction is along the rotation axis. The z-direction is in the radial direction of the in-wheel motor 200. The electric fan 150 is arranged to displace the gas 160 through the through-hole 210. As shown in FIG. 2, the electric fan 150 is arranged on the left side of the stator 102. The electric fan 150 is attached to the stator 102. The electric fan 150 propels the gas 160 in the axial direction to displace the gas 160 from the left side of the stator 102 to the right side of the stator 102 via the through-hole 210. The gas 160 flows via the magnetic gaps 118 back to the electric fan 150 by flowing radially inward.

[0065] The in-wheel motor 200 comprises a guiding element 214. The rotor 110 comprises a rotor surface 220. The guiding element 214 is arranged on the rotor surface 220. The electric fan 150 is arranged radially inward of the electromagnets 104. The electric fan 150 is arranged to displace the gas 160 towards the rotor surface 220. The guiding element 214 is adapted to divide the gas 160 into a radially outward flow 160B and a radially inward flow 160A. The radially outward flow 160B and the radially inward flow 160A are indicated by the two curved arrows. The guiding element 214 is arranged axisymmetrically along the rotation axis of the in-wheel motor 200. That is why the guiding element 214 is depicted twice in FIG. 2. By arranging the guiding element axisymmetrically, there is always a part of the guiding element 214 facing the through-hole 210, independently of the rotational position of the rotor 110. Alternatively, the guiding element 214 is not axisymmetrically, but rotational symmetrically. For example, the guiding element 214 comprises multiple elements that are separate from each other and which are arranged rotational symmetrically relative to the rotation axis on the rotor surface 220.

[0066] The in-wheel motor 200 comprises a plurality of fins 212. The fins 212 are arranged on the rotor surface 220. The fins 212 provide an additional surface that contacts the gas 160 to improve the heat transfer from the gas 160. The fin 212 is for example shaped as a spiral. The spiral shaped is formed on the rotor surface 220. The spiral shape is, for example, made by a single fin 212, or made by a plurality of fins 212 that positioned along a spiral shaped line on the rotor surface 202.

[0067] It is noted that applications with more than one fan are foreseen, as well as applications in which the orientation of the axis of the fan 150 is axial or radial. It might be beneficial to pulsate the air circulation by varying the fan speed, or to change the direction of the air stream by (temporarily) reversing the fan's rotation direction.

[0068] Through holes in the stator 102 near or between the electromagnets 104 may also have a beneficial effect for the cooling of the electromagnets 104.

[0069] This invention may be combined with a mechanical ventilator, for example a ventilator described in patent publication KR101330694B1.