FR3046128A1 - ELECTRIC WHEEL AND CONTROL METHOD THEREFOR - Google Patents

Abstract

The invention relates to an electric wheel (10) comprising: - an axis of rotation (11), - an electric motor (12), - a storage element (14) of electrical energy, and - an enclosure (15) comprising a primary flange (16) and a secondary flange (17), - said primary flange (16) comprising housings (20, 21) extending transversely with respect to said electric wheel (10), - said primary flange (16) being made of a heat-transfer metallic material so that the heat produced by said electric motor (12) and / or said at least one storage element (14) is radiated, at least in part, at a transverse end of said housing (20, 21), and - at least one heat dissipation zone being disposed between a first housing (20) supporting the electric motor (12) and a second housing (21) supporting the storage element (14) so as to limit heat exchange.

Description

ELECTRIC WHEEL AND CONTROL METHOD THEREFOR

Technical Field The invention relates to the field of autonomous motorized electric wheels. The invention relates more particularly to electric wheels that can be used on transport vehicles such as electric wheelchairs, carriages and wheelbarrows, for example. The invention finds a particularly advantageous application for vehicles operating in a difficult environment, that is to say in water or on sand.

Previous art

The electric wheels are defined as the wheels incorporating an electric motor capable of driving the axis of the wheel. The autonomous electric wheels correspond more particularly to the wheels incorporating an energy storage device capable of supplying the electric motor.

These autonomous electric wheels conventionally comprise a housing arranged around the wheel so as to protect the axis of the wheel and the electrical elements, engine and energy storage device. However, this housing is usually made of metal and conducts heat between the engine and the energy storage device. It follows that the engine heat is transmitted to the energy storage device and degrades performance. In addition, this housing also transmits to the electrical elements it contains, the heat generated by the sun's rays striking the housing. The removal of heat is an important issue in order to preserve the proper functioning of the electronic equipment present in the engine and the energy storage device. Indeed, these various electronic equipment are subject to strict operating constraints. In order to operate optimally, the temperature of an engine should preferably be less than 80 ° C and for a battery of lithium-ion technology the temperature should preferably be below 60 ° C.

However, the external radiation and the power dissipated by the electric motor and the energy storage device can cause rises in temperatures above 100 ° C.

Another technical constraint of these autonomous electric wheels relates to the necessary sealing in order to allow a vehicle incorporating an autonomous electric wheel to evolve in a difficult medium namely liquid or similar, that is to say in water or on sand.

To at least partially meet these constraints, the International Patent Application No. WO 2004/050385 discloses an autonomous electric bicycle wheel having an enclosure within which are formed two housing. A first housing makes it possible to fix the motor driving the axis of the wheel and a second housing makes it possible to fix the energy storage devices. The two housings are fixed inside the enclosure by aluminum boxes spaced from the walls of the enclosure, so as to limit the heating due to sunlight on the walls of the enclosure. In addition, the two housings are spaced relative to each other to limit heat exchange between the engine and the storage devices.

However, the distance imposed between the engine, the storage devices and the walls of the enclosure limits the capacity of the energy storage devices. Indeed, to meet these constraints, the energy storage devices must have a very low volume which limits their capacity. In addition, it is very complex to ensure both a seal of the autonomous electric wheel and to ensure heat dissipation inside the enclosure of the wheel because the seal has the effect of confining the air inside the wheel which limits the possible circulation of this air. Other solutions propose using an active cooling system using a heat transfer fluid. However, these cooling systems have a negative impact on the size and weight of the wheel due to the use of the cooling system coupled with a fluid entrainment device. Other solutions propose to use modules peltiers which minima are strongly energy consuming.

The technical problem of the invention therefore consists in improving the arrangement of an autonomous electric wheel provided with passive cooling.

Expose the invention

The present invention aims to address this technical problem by using a chamber made in two parts by means of a primary flange and a secondary flange. The primary flange is configured to perform a dual function of maintenance and heat dissipation between the two electrical elements (motor and storage elements) and the outside. The thermal transmission between the electrical elements (motor and storage elements) is reduced by heat dissipation zones. For this purpose, according to a first aspect, the invention relates to an electric wheel comprising an axis of rotation, an electric motor comprising means driving said axis of rotation, at least one storage element of an electrical energy and an enclosure surrounding said electric motor and said at least one storage element. Moreover, said at least one storage element is connected to said electric motor so as to supply said electric motor. The invention is characterized in that said enclosure comprises a primary flange forming a first side of said electric wheel, and a secondary flange forming a second side of said electric wheel. More specifically, said primary flange comprises housing extending transversely relative to said electric wheel. Said electric motor is fixed in a first housing and said at least one storage element is fixed in at least a second housing. In addition, said primary flange is made, at least in part, in a material whose thermal conductivity is greater than 10 Watt per meter-kelvin so that the heat produced by said electric motor and / or said at least one storage element is radiated, at least in part, at a transverse end of said housing.

At least one heat dissipation zone is also disposed between said first housing and said at least one second housing so as to limit heat exchanges between said electric motor and said at least one storage element. The invention thus makes it possible to achieve the heat dissipation between the two electrical elements directly at the level of the primary flange forming the enclosure. There is thus a temperature gradient between the engine and the at least one storage element. In addition, the thermal conduction path between the two components is controlled. Thus, failing to completely cancel this thermal conduction, it is easier to estimate this thermal conduction since it is targeted.

It follows that the storage capacity inside the enclosure is increased compared to the devices of the prior art. In addition, the invention facilitates the realization of a seal of the enclosure of the autonomous electric wheel because the cooling of the electrical elements does not use the internal air of the enclosure.

Said at least one second housing corresponds to three distinct variants in which: a single housing integrates one or more energy storage elements, a plurality of energy storage elements are arranged in a plurality of housings and a plurality of dwellings each integrate a plurality of storage elements; 'energy.

According to one embodiment, said primary flange has an opening at the axis of rotation, said opening being intended to connect the axis of rotation with a vehicle located outside said enclosure and close to said primary flange. This embodiment makes it possible to protect the primary flange of the sun's rays by using the structure of the vehicle positioned next to the electric wheel. The cutting of the enclosure into two flanges is particularly effective with this embodiment, because the primary flange acts as a heat sink away from the sun, while the secondary flange is configured to reflect and / or absorb the rays of the sun without transmitting this resulting heat to the electric elements.

According to one embodiment, the wheel comprises at least one rib coming from material with said primary flange and extending transversely relative to said electric wheel at a transverse end of said housing.

This embodiment improves the heat dissipation at the housing level. In addition, the ribs also improve the rigidity of the primary flange.

According to one embodiment, said at least one rib has a spiral shape extending from a radial end of said primary flange to an outer face of said housing. This embodiment makes it possible to recover the external water when the electric wheel moves on a low water level, that is to say when the water does not reach the level of the axis of the water. wheel. In this case, the water is directed by the spiral shape in the manner of a blade wheel to the housing so as to cool the primary flange by heat exchange.

According to one embodiment, said heat dissipation zone is formed by a discontinuity of material between a first rib connected to said first housing and a second rib connected to said at least one second housing. This embodiment contributes to slowing the propagation of heat from the engine to the storage device.

According to one embodiment, an insert is disposed around said first housing, said insert having a thermal conductivity lower than the thermal conductivity of said first housing. This embodiment also helps to slow the propagation of heat from the engine to the storage device.

According to one embodiment, said heat dissipation zone is formed by a spacing between said first housing and said at least one second housing, said spacing having a length at least greater than 10% of the radius of said electric wheel. This embodiment also helps to slow the propagation of heat from the engine to the storage device.

According to one embodiment, said secondary flange is connected to said primary flange through a material configured to provide thermal insulation between the two flanges.

This embodiment limits the heat exchange between the two flanges so that the heat generated by the sun striking the secondary flange is not directly transmitted to the primary flange. There is thus a temperature gradient between the two flanges.

According to one embodiment, said primary flange comprises an outer coating configured to promote heat exchange between said primary flange and the outside of said enclosure. This embodiment promotes heat exchange between the primary flange and the outside of the wheel. Alternatively, the secondary flange also has a coating configured to limit the heat input from the sun, and / or to promote heat exchange with the outside.

According to one embodiment, the two flanges are connected by at least one heat pipe so as to evacuate at least a portion of the heat generated on said primary flange to said secondary flange. This embodiment makes it possible to evacuate part of the heat from the primary flange by the secondary flange. This embodiment is particularly advantageous when the outside temperature is low and the secondary flange is not heated by the sun, for example at night.

According to one embodiment, said primary flange comprises at least one temperature sensor disposed between said housings for estimating a thermal transmission between said electric motor and said at least one storage element.

According to one embodiment, said electric wheel comprises four temperature sensors: a first temperature sensor disposed at said first housing and configured to measure the heat of said electric motor; a second temperature sensor disposed at said at least one second housing and configured to measure the heat of said at least one storage element; - a third temperature sensor disposed on a rib of said primary flange and configured to measure external heat; and - a fourth temperature sensor disposed on said secondary flange and configured to measure the heat of said secondary flange.

According to a second aspect, the invention relates to a method of controlling an electric wheel according to the previous embodiment, comprising the following steps: - the acquisition of measurements from said temperature sensors; determining a perspective of evolution of the temperature of said at least one storage element; and when said perspective of evolution of the temperature of said at least one storage element exceeds a threshold value, the implementation of means for limiting the temperature generated by said electric motor.

This embodiment aims to anticipate a rise in temperature of the at least one storage element.

According to one embodiment, the limiting means consist of an alert to the user so that it regulates the speed of said electric motor of said electric wheel.

According to one embodiment, the limiting means consist in limiting the torque of said electric motor of said electric wheel by a device for regulating a control of said electric motor.

Brief description of the figures

The manner of carrying out the invention as well as the advantages derived therefrom, will emerge clearly from the following embodiment, given by way of indication but without limitation, in support of the appended figures in which FIGS. 1 to 9 represent: FIG. 1: a schematic representation in section of an autonomous electric wheel according to a first embodiment of the invention; - Figure 2: a schematic representation in section of an autonomous electric wheel according to a second embodiment of the invention; - Figure 3: a schematic representation in side view of the primary flange of the electric wheel of Figure 1; - Figure 4: a schematic representation in side view of a primary flange of an electric wheel according to a second embodiment; - Figure 5: a schematic sectional representation of an autonomous electric wheel according to a third embodiment of the invention; - Figure 6: a graphical representation of a method for predicting a rise in temperature of the energy storage element of the electric wheel of Figure 5; - Figure 7: a schematic representation of the control process of the electric wheel of Figure 5; - Figure 8: a schematic sectional representation of an autonomous electric wheel according to a fourth embodiment of the invention; and FIG. 9 is a schematic sectional representation of a motor of an autonomous electric wheel mounted in an insert according to a fifth embodiment of the invention.

Detailed description of the invention

FIG. 1 illustrates an electric wheel 10a formed by an enclosure 15 movable about an axis of rotation 11. A radial end of the enclosure 15 forms a rim 42 supporting a tire 41.

In the orthonormal X / Y coordinate system illustrated in FIG. 1, the electric wheel 10a rotates about the Y axis and extends radially along the X axis. These directions are intended only to present the operation of the electric wheel 10a. and may vary without changing the invention.

The electric wheel 10a also comprises an electric motor 12 disposed in the enclosure 15 and configured to drive the shaft 11 via drive means 13, for example a belt or a gear. The electric motor 12 is powered by energy storage elements 14 also arranged in the enclosure 15. The enclosure 15 is composed of two parts interconnected: a primary flange 16a and a secondary flange 17. The primary flange 16a extends circumferentially around the axis 11 and then radially up to the rim 42.

Preferably, the rim 42 is formed by a U-shaped portion extending at the radial end of the primary flange 16a as illustrated in FIG. 1. The secondary flange 17 has a domed central face connected by its radial ends. with the primary flange 16a.

Alternatively, the shape of the two flanges 16a, 17 and the rim 42 can vary without changing the invention. According to the invention, the primary flange 16a is structured so as to form housings 20, 21 for fixing the electrical elements 12, 14 and for dissipating the heat outside the electric wheel 10a. For this purpose, the first housing 20 matches the outer shape of the electric motor 12 and the second housing 21 follow the outer shape of the energy storage elements 14. The electrical elements 12, 14 can be fixed in the housings 20, 21 by any known means: gluing, fitting in form, screwing, etc.

In order to dissipate the heat generated by the electrical elements 12, 14 towards the outside of the electric wheel 10a, the primary flange 16a is produced, at least in part, in a material whose thermal conductivity is greater than 10 Watt per meter. kelvin. Thermal conductivity or thermal conductivity is a physical quantity characterizing the behavior of materials during conductive heat transfer. It represents the energy or amount of heat transferred per unit area and time under a temperature gradient of 1 kelvin per meter. Materials with a thermal conductivity greater than 10 Watt per meter-Kelvin include, for example, titanium (20 Watt per meter-kelvin), aluminum (237 Watt per meter-kelvin), copper (390 Watt per meter) -kelvin), iron (80 Watt per meter-Kelvin). Alternatively, a non-metallic material may be used provided that its thermal conductivity is greater than 10 Watt per meter-Kelvin. Preferably, the primary flange 16a is made of aluminum so as to use the intrinsic heat transfer and lightness properties of the aluminum. The invention also aims to create at least one heat dissipation zone disposed between the housing 20 of the electric motor 12 and the housings 21 of the energy storage elements 14. This heat dissipation zone has the function of limiting the exchanges of heat between the electric elements 12, 14.

This heat dissipation zone can be realized in several different ways that can be implemented independently or in combination.

For another example, as shown in FIG. 3, the heat dissipation zone is made by a spacing 30 between the first housing 20 and the second housing 21. This spacing 30 is illustrated in FIG. 3. In this example, the spacing 30 has a length at least greater than 10% of the radius of the electric wheel 10. The length of the spacing 30 is determined by the smallest distance between the first housing 20 and the nearest second housing 21 such as shown in Figure 3.

In addition, the rigidity of the primary flange 16a can be increased by ribs 27, 28, 31, 32 coming from material with the primary flange 16a and extending transversely with respect to the electric wheel 10 at a transverse end of the flanges. housing 20, 21. These ribs 27, 28, 31, 32 improve both the rigidity of the primary flange 16a and the heat dissipation at the housing 20, 21.

3 illustrates an embodiment in which ribs 27, 28 have a spiral shape extending from a radial end of the primary flange 16a to an outer face of said housings 20, 21. This embodiment is advantageously when the 10a electric wheel rotates in the direction S in a medium having a water level 43. The water is not in direct contact with the housing 20, 21 and does not directly to cool these housing 20, 21.The form spiral ribs 27, 28 then captures the water below the water level 43 to transmit it at the housing 20, 21 and cool the outer face of the primary flange 16a.

4 illustrates a variant of the primary flange 16b in which ribs 31, 32 are associated with the ribs 27, 28 shown in FIG. 3. A first rib 31 forms an arc of a circle between the second housings 21 so as to dissipate the heat. second housings 21 in a homogeneous manner. A second rib 32 forms an arc at the first housing 20.

In this embodiment, the heat dissipation zone is also formed by a discontinuity of material between the first rib 31 and the second rib 32.

In addition, the primary flange 16 has an opening at the axis of rotation 11. This opening 25 is intended to connect the axis of rotation 11 with a vehicle located outside the chamber 15 and close to the primary flange 16 This clever position of the electric wheel 10a serves to protect, at least in part, the primary flange 16 of the sun's rays.

Alternatively, the primary flange 16 may be connected to the secondary puddle 17 by means of a material configured to provide thermal insulation between the two flanges 16, 17. Alternatively, the primary flange 16 may comprise an outer coating configured to promote heat exchange between the primary flange 16 and outside said enclosure 15.

Alternatively, as shown in Figure 2, the two flanges 16a, 17 of the electric wheel 10b are connected by heat pipes 40 so as to evacuate at least a portion of the heat generated on the primary flange 16a to the secondary flange 17.

As a variant, as illustrated in FIG. 5, the energy storage elements 14 are covered by a protective cap 44 able to limit the heat exchanges with the air contained in the enclosure 15. FIG. an autonomous electric wheel 10c controlled in temperature. For this purpose, the electric wheel 10c has four temperature sensors Te, Tf, Te and Ts. The first temperature sensor Te is disposed at the first housing 20, this sensor measures the temperature at the generally hottest point due to heating of the electric motor 12.

The second temperature sensor Tf is disposed at the second housing 21, this sensor measures the temperature at the critical point at which the temperature should not exceed a threshold value A, for example 60 ° C in the case of batteries technology lithium / ion. A third temperature sensor Te is disposed on a rib 28 so as to measure the outside temperature. A fourth temperature sensor Ts is disposed on the secondary flange 17 so as to measure the heat generated by the sun on the secondary flange 17.

These sensors make it possible to supervise the temperature in different points of the enclosure 15 and thus to predict the exceeding of the threshold temperature A at the level of the energy storage elements 14. The prediction of the temperature at the level of the storage elements of energy 14 can simply be performed by a linear progression of the sum of the temperatures measured at an instant T o as shown in FIG. 6. This linear progression makes it possible to determine the time T a before the threshold temperature A is crossed by the wheel Electric 10c. If the time At is less than a second threshold value, then measures can be implemented to limit the generation of heat at the electric motor 12. Alternatively, other models of temperature progression can be implemented without changing the invention. Alternatively, measurements may be made at other points of the electric wheel 10c and the number of measurements may also vary without changing the invention.

Figure 7 illustrates a method of controlling the electric wheel 10c using the measurements from the temperature sensors. A calculator 50 estimates, over time, the time At before the threshold temperature A is crossed by the electric wheel 10c.

When the time At is lower than a first threshold value dti, an audible or visual warning device 51 is triggered to warn the user to adapt his driving and thus limit the power demanded from the electric motor 12. When the time At is lower at a second threshold value dt2, the control member 52 of the electric motor 12 will be directly impacted. Indeed, the control member 52 normally responds to a set point 53 of a user.

When the time At is less than the second threshold value dt2, the instruction 53 of the user will be reduced at the control member 52. It follows that these measures make it possible to limit the generation of heat at the level of the electric motor 12 and thus to improve the service life and the performance of the energy storage elements 14.

In addition, the invention also makes it possible to obtain an autonomous and sealed electric wheel because the air circulating in the enclosure 15 is not used to achieve heat dissipation. Thus, the air circulating in the enclosure does not need to be exchanged with the outside air.

As a variant, as illustrated in FIG. 8, the electric wheel 10d also comprises means for forced ventilation at the primary flange 16. These forced ventilation means are provided by a ventilation motor 60 disposed in the near enclosure 15 storage elements 14. The ventilation motor 60 actuates a turbine 61 disposed outside the enclosure 15 so as to generate a flow of air F able to cool the housing 20, 21.

Alternatively, as shown in Figure 9, the motor 12 is mounted in the first housing through a thermally insulating insert 65. For example, the insert 65 may be made of plastic. The insert 65 is considered thermally insulating because it has a thermal conductivity at least five times lower than the thermal conductivity of the first housing 20. The insert 65 slows the propagation of heat from the motor 12 to the storage device 14.

The electric wheel 10 can be controlled by a radio control type wifi or bluetooth. Alternatively, the electric wheel 10 can be controlled by a wire extending outside the electric wheel 10. The use of a single wire extending outside the electric wheel 10 is easier to achieve than to use several wires for passing the power supply of the electric wheel 10 by arranging the energy storage elements outside the electric wheel 10.

Claims (15)

Electric wheel (10) comprising: - an axis of rotation (11), - an electric motor (12) comprising drive means (13) for said axis of rotation (11), - at least one storage element ( 14) of an electrical energy, said at least one storage element (14) being connected to said electric motor (12) so as to supply said electric motor (12), and - an enclosure (15) surrounding said electric motor (12) ) and said at least one storage element (14), characterized in that said enclosure (15) comprises: - a primary flange (16) forming a first side of said electric wheel (10), and - a secondary flange (17) ) forming a second side of said electric wheel (10), - said primary flange (16) having recesses (20, 21) extending transversely with respect to said electric wheel (10), said electric motor (12) being fixed in a first housing (20) of said housings (20, 21), - said at least one element storage device (14) being fixed in at least a second housing (21) of said housings (20, 21), - said primary flange (16) being made, at least in part, in a material whose thermal conductivity is greater than 10 Watt per meter-kelvin so that the heat generated by said electric motor (12) and / or said at least one storage element (14) is radiated, at least in part, at a transverse end of said housing (20). , 21), and - at least one heat dissipation zone being disposed between said first housing (20) and said at least one second housing (21) so as to limit heat exchanges between said electric motor (12) and said least one storage element (14). 2. Electric wheel according to claim 1, characterized in that said primary flange (16) has an opening (25) at the axis of rotation (11), said opening (25) being intended to connect the axis of rotation. rotation (11) with a vehicle situated outside said enclosure (15) and close to said primary flange (16). 3. Electric wheel according to claim 1 or 2, characterized in that it comprises at least one rib (27, 28, 31, 32) integral with said primary flange (16) and extending transversely relative to said electric wheel (10) at a transverse end of said housing (20, 21). 4. Electric wheel according to claim 3, characterized in that said at least one rib (27, 28) has a spiral shape extending from a radial end of said primary flange (16) to an outer face of said housings (20). , 21). 5. Electric wheel according to claim 3 or 4, characterized in that said heat dissipation zone is formed by a discontinuity of material between a first rib (30) connected to said first housing (20) and a second rib (31) connected to said second housing (21). 6. Electric wheel according to one of claims 1 to 5, characterized in that it also comprises an insert (65) disposed around said first housing (20), said insert (65) having a thermal conductivity lower than the thermal conductivity said first housing (20). 7. Electric wheel according to one of claims 1 to 6, characterized in that said heat dissipation zone is formed by a spacing (30) between said first housing (20) and said at least one second housing (21), said spacing (30) having a length at least greater than 10% of the radius of said electric wheel (10). 8. Electric wheel according to one of claims 1 to 7, characterized in that said secondary flange (17) is connected to said primary flange (16) through a material configured to achieve thermal insulation between the two flanges (16, 17). 9. Electric wheel according to one of claims 1 to 8, characterized in that said primary flange (16) comprises an outer coating configured to promote heat exchange between said primary flange (16) and the outside of said enclosure (15). ). 10. Electric wheel according to one of claims 1 to 9, characterized in that the two flanges (16, 17) are connected by at least one heat pipe (40) so as to evacuate at least a portion of the heat generated on said primary flange (16) to said secondary flange (17). 11. Electric wheel according to one of claims 1 to 10, characterized in that said primary flange (16) comprises at least one temperature sensor disposed between said recesses (20, 21) for estimating a thermal transmission between said engine electrical device (12) and said at least one storage element (14). 12. Electric wheel according to one of claims 1 to 11, characterized in that said electric wheel (10) comprises four temperature sensors: a first temperature sensor (Te) disposed at said first housing (20) and configured for measuring the heat of said electric motor (12); - a second temperature sensor (Tf) disposed at said at least one second housing (21) and configured to measure heat of said at least one storage element (14); a third temperature sensor (Te) disposed on a rib (27, 28, 31, 32) of said primary flange (16) and configured to measure the external heat, and - a fourth temperature sensor (Ts) disposed on said secondary flange (17) and configured to measure the heat of said secondary flange (17). 13. A method of controlling an electric wheel according to claim 12, comprising the following steps: - the acquisition of measurements from said temperature sensors (Te, Tf, Te, Ts); determining a perspective for changing the temperature of said at least one storage element (14); and when said perspective of evolution of the temperature of said at least one storage element exceeds a threshold value, the implementation of means for limiting the temperature generated by said electric motor (12). The method of controlling an electric wheel according to claim 13, wherein the limiting means comprises an alert for use to regulate the speed of said electric motor (12) of said electric wheel (10). ). 15. A method of controlling an electric wheel according to claim 13 or 14, wherein the limiting means consist in limiting the torque of said electric motor (12) of said electric wheel (10) by a regulating device of a controlling said electric motor (12).