THERMAL INSULATION DEVICE FOR BRAKES FOR ELECTRIC WHEEL MOTORS OF MOTOR VEHICLES

Abstract

The invention relates to a thermal insulation device for a disc brake (3) associated with an electric motor (2) for wheels (1) of motor vehicles, said motor comprising a stator (20) mounted on the central axle (X) of the wheel and a rotor (21) mounted, on the one hand, on the wheel rim (11) and, on the other hand, on the brake disc (3) via peripheral fastening members (5), characterized in that said fastening members (5) are provided with spacers (4) of thermally insulating material disposed between the disc (3) and the rotor (21). (Fig. 1)

Description

Title of the invention: THERMAL INSULATION DEVICE FOR BRAKES FOR ELECTRIC WHEEL MOTORS OF MOTOR VEHICLES

[0001] The invention relates, in general, to the field of electric motorization of motor vehicles and is interested, more particularly, in a device intended to thermally insulate the brakes of electric motors intended to be integrated into the wheels to provide traction for these vehicles.

[0002] The motorization of certain electric vehicles is provided not by means of a central motor but via motors directly integrated into the wheels. This type of motorization, with one or more driven wheels, frees up space in the engine compartment for the installation of batteries and also offers advantages in terms of road handling.

[0003] These electric motors are mounted in the wheels, such that the stator is located on the central axle and the rotor inside the wheel rim. Such a motor is generally equipped with a disc brake connected to the rotor and fitted with a caliper.

[0004] During braking, the friction of the discs against the rotor generates intense heat (the disc temperature can reach approximately 800°C) which is transferred by conduction to the motor. However, this heat can damage the motor and, in particular, the windings and magnets, which are especially sensitive to high temperatures.

[0005] Patent JP4391884B2 describes a thermal insulation device for disc brakes comprising a ceramic washer designed to limit the conduction of heat generated by the discs during braking to the disc mounting elements. However, this device is not suitable for the brakes of electric wheel motors, whose discs act directly on the rotor, and therefore does not provide thermal insulation for the essential components of these motors.

[0006] In this problematic context, the invention sought a technical solution enabling the integration of thermal insulation means between the brake discs and the engine, in order to reduce their contact surfaces and protect the latter.

[0007] This goal is achieved, according to the invention, by means of a thermal insulation device for the disc brake associated with an electric wheel motor for motor vehicles, said motor comprising a stator mounted on the central axis of the wheel and a rotor mounted, on the one hand, on the wheel rim and, on the other hand, on the brake disc via peripheral fixing members, characterized in that said fixing members are provided with spacers of thermally insulating material disposed between the disc and the rotor.

[0008] According to an advantageous feature of the isolation device of the invention, the spacers are mounted on either side of the brake disc.

[0009] According to an alternative embodiment of the isolation device of the invention, the rotor is mounted coaxially to the stator and fixed on a radial shoulder extending inside the rim.

[0010] According to another advantageous feature of the isolation device of the invention, the fixing members are screwed into bores parallel to the wheel axis made in the rotor and through the brake disc and the rim.

[0011] According to a first specific embodiment of the invention, the spacers are arranged around each fastening member and distributed between spacers external to the brake disc and internal spacers interposed between the disc and the rotor.

[0012] Preferably, the inner spacers are inserted between the disc and the rim.

[0013] According to another specific embodiment of the invention, the spacers are made in the form of washers and the inner spacers are wider and thicker than the outer spacers.

[0014] According to yet another feature of the insulation device of the invention, the spacers are made with a material of very low thermal conductivity chosen from among phenolic resins.

[0015] Another object of the invention is a motor vehicle equipped with electric traction motors integrated into at least one of its wheels and associated with disc brakes, characterized in that it includes a thermal insulation device for the brake discs as defined above.

[0016] Thanks to the invention, the electric wheel motor is effectively protected from high temperatures by thermally insulating spacers that prevent the conduction of heat generated by the discs during braking. The invention thus ensures proper operation and efficiency of the electric wheel motor.

[0017] While reducing the contact area between the brake discs and the motor, the insulating spacers used in the device of the invention also make it easier to position and center the disc on the motor rotor.

[0018] Wheel electric motors thus protected by the device of the invention constitute an excellent alternative to central electric motors. Indeed, their use in electric vehicles frees up space in the engine compartment for the installation of a greater number of batteries, which offers a significant increase in the vehicle's range.

[0019] Moreover, the invention makes it possible to undersize the brakes since these are intended to act locally on each motorized wheel, which offers a significant economic gain.

[0020] Finally, the factory assembly operations of the vehicle are facilitated by the fact that the wheels are already pre-equipped with their brakes.

[0021] Other features and advantages of the invention will become apparent from the following description, with reference to the accompanying figures, for which:

[0022] [Fig.1] is a perspective view of a motor vehicle wheel equipped with an integrated electric motor provided with the thermal insulation device according to the invention.

[0023] [Fig.2] is a front view of the wheel of [Fig.1].

[0024] [Fig.3] is a cross-sectional view along AA of the wheel in Figures 1 and 2.

[0025] [Fig.4] is a cross-sectional view along BB of the wheel of figures 1 and 2.

[0026] [Fig. 5] is a detailed cross-sectional view along BB of the insulation device integrated into the wheel in figures 1 and 2.

[0027] For clarity, identical or similar elements are identified by identical reference signs throughout the figures.

[0028] Naturally, the embodiments of the insulation device according to the invention, schematically illustrated in the figures above and described below, are given only by way of non-limiting examples. It is explicitly provided for within the scope of the invention that different embodiments can be proposed and combined to create others.

[0029] The invention relates to the general field of electric motorization of motor vehicles and is more particularly concerned with the problem of thermal insulation of brake discs of electric traction motors integrated into the wheels of these vehicles.

[0030] The motorization of certain electric vehicles is achieved by means of traction motors integrated into the wheels and equipped with disc brakes. Traditionally, and as illustrated by Figures 1 and 2, these motorized wheels 1 comprise a rim 11, a stator 20 of an asynchronous electric motor 2 mounted on the central axis X of the wheel, and a rotor 21. This rotor 21 is mounted coaxially to the stator 20, on the one hand, on the rim 11 and, on the other hand, on the brake disc 3 via peripheral mounting members 5. The disc brake 3 further comprises a caliper 31.

[0031] During braking, the friction of the disc 3 against the stator 20 generates significant heat (with the disc temperature potentially reaching approximately 800°C). Due to the structure of the wheel 1, this heat is transmitted by conduction to the motor via the mounting elements 5. This heat can damage the motor, and in particular the windings and magnets, which are especially sensitive to high temperatures. This results in serious risks of engine malfunction, or even destruction of its essential component parts.

[0032] The invention therefore consists of proposing a device for isolating the brake disc 3 which makes it possible to block, or at least significantly reduce, the impact on the engine of this heat conduction phenomenon.

[0033] For this purpose, the fixing members 5 of the rotor 21 of the motor on the brake disc 3 are provided, according to the invention, with spacers 4 made of thermally insulating material arranged between the disc 3 and the rotor 21 and, preferably, on either side of the disc 3, as illustrated by figures 4 and 5.

[0034] Because, in the embodiment shown here in the figures, the rotor 21 is fixed on a radial shoulder 1 extending inside the rim 11, the fixing members 5 are screws engaged and tightened in bores 5a parallel to the axis X of the wheel 1 made in the rotor 21 and through the brake disc 3 and the rim 11.

[0035] The spacers 4 are arranged around each fastening member 5 and distributed between spacers 41 external to the brake disc 3 and internal spacers 42 interposed between the disc 3 and the rotor 21 and, here, between the disc 3 and the rim 11, as illustrated by [Fig.5].

[0036] Preferably, the spacers are made in the form of washers and the inner spacers 42 are wider and thicker than the outer spacers 4L

[0037] These spacers are made with a material of very low thermal conductivity chosen from among phenolic resins such as Bakelite (registered trademark).

Claims

Demands

1. Thermal insulation device for the disc brake (3) associated with an electric motor (2) of wheels (1) for motor vehicles, said motor comprising a stator (20) mounted on the central axis (X) of the wheel and a rotor (21) mounted, on the one hand, on the wheel rim (11) and, on the other hand, on the brake disc (3) via peripheral fixing members (5), characterized in that said fixing members (5) are provided with spacers (41, 42) of thermally insulating material disposed between the disc (3) and the rotor (21).

2. Device according to claim 1, characterized in that said spacers (41, 42) are mounted on either side of the brake disc (3).

3. Device of one of the preceding claims, characterized in that the rotor (21) is mounted coaxially to the stator (20) and fixed on a radial shoulder (lia) extending inside the rim (11).

4. Device of one of the preceding claims, characterized in that said fastening members (5) are screwed into bores (50) parallel to the axis (X) of the wheel (1) made in the rotor (21) and through the brake disc (3) and the rim (11).

5. Device of one of the preceding claims, characterized in that said spacers (41, 42) are arranged around each fastening member (5) and distributed between spacers (41) external to the brake disc (3) and internal spacers (42) interposed between the disc (3) and the rotor (21).

6. Device of the preceding claim, characterized in that the inner spacers (42) are interposed between the disc (3) and the rim (11).

7. Device according to claim 5 or 6, characterized in that the inner spacers (42) are wider and thicker than the outer spacers (41).

8. Device one of the preceding claims, characterized in that said spacers (41, 42) are made in the form of washers.

9. Device of one of the preceding claims, characterized in that said spacers (41, 42) are made with a material with very low thermal conductivity selected from phenolic resins.

10. A motor vehicle equipped with electric traction motors integrated into at least one of its wheels (1) and associated with disc brakes (3), characterized in that it comprises a device for thermally insulating the brake discs according to one of the preceding claims.

Images