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EP-4539038-B1 - ELECTRIC PROPULSION APPARATUS FOR A MOTOR VEHICLE WITH GENERATION OF SOUNDS DEPENDING ON THE OPERATION THEREOF

EP4539038B1EP 4539038 B1EP4539038 B1EP 4539038B1EP-4539038-B1

Inventors

  • Lavacchielli, Gianluca
  • FERRARA, DAVIDE
  • PULVIRENTI, FRANCESCO
  • QUATTROMANI, Gianluca
  • QUONDAM ANTONIO, Simone

Dates

Publication Date
20260513
Application Date
20241008

Claims (10)

  1. Propulsion apparatus for a motor vehicle (1), the apparatus comprising - an electric motor (5) configured to emit a rotating magnetic field during operation, and characterized by comprising - at least one harmonic oscillator (11, 12, 13) arranged to interact with the rotating magnetic field emitted by the motor (5), wherein the harmonic oscillator (11, 12, 13) comprises at least one support (14), a first magnet (15, 16, 17, 21) arranged to have a first magnetic pole exposed to the rotating magnetic field emitted by the electric motor (5), and an elastic element (18) suspending the first magnet (15, 16, 17, 21) to the support (14), such that the first magnet (15, 16, 17, 21) oscillates with respect to the support (14) as a function of the rotating magnetic field, thereby inducing a sound pressure wave corresponding to the oscillation of the first magnet (15, 16, 17, 21) and the elastic element (18).
  2. The apparatus according to claim 1, wherein the electric motor (5) comprises a rotor (7) and a stator (8) coaxial about a rotor axis (R), the rotor (7) being rotatable with respect to the stator (8) about the rotor axis (R) and comprising a second magnet (10) with a magnetic axis radial with respect to the rotor axis (R), the second magnet (10) being axially facing the first pole according to the rotor axis (R).
  3. The apparatus according to claim 2, wherein the rotor (7) comprises a radial magnetic interaction portion (7c) configured to magnetically interact with the stator (8) according to a radial direction with respect to the rotor axis (R) and an axial end portion (7b), according to the rotor axis (R), comprising the or defined by the second magnet (10) and fixed with respect to the radial magnetic interaction portion (7c).
  4. The apparatus according to any one of the preceding claims, further comprising an additional harmonic oscillator (11, 12, 13, 20) with a third magnet (15, 16, 17, 21) arranged to have a second magnetic pole exposed to the rotating magnetic field emitted by the electric motor (5).
  5. The apparatus according to claim 4, in which the harmonic oscillators (11, 12, 13, 20) have natural frequencies different from each other.
  6. The apparatus according to claim 4 or 5, wherein the third magnet (15, 16, 17, 21) is arranged to have a position diametrically opposite to the first magnet (15, 16, 17, 21) with respect to an axis of rotation (R) of the rotating magnetic field, and wherein the second magnetic pole has a magnetic polarity opposite to the first magnetic pole.
  7. The apparatus according to any of the preceding claims, comprising sound transmission means (22) configured to transmit the sound pressure wave to a passenger compartment of the motor vehicle (1).
  8. The apparatus according to claim 7, wherein the sound transmitting means (22) comprise a tube (23) having a first end (23a) disposed at the harmonic oscillator (11, 12, 13), the tube (23) being configured to extend up to terminate with a further end (23b) to be put in communication with the passenger compartment.
  9. The apparatus according to claim 8, wherein the elastic element (18) comprises an axially deformable elastic tubular body, preferably of the bellows type, the tubular body (18) being communicating with and carried by the first end (23a) of the tube (23).
  10. Motor vehicle (1) comprising a propulsion apparatus according to any of the preceding claims.

Description

TECHNICAL FIELD The invention relates to an electric propulsion apparatus for a motor vehicle and, more specifically, the aspect of the sound emission of the apparatus. PRIOR ART Some motor vehicles only use electric motors as propulsion means and, therefore, are commonly called fully electric or, simply, electric vehicles. During their operation, the electric motors emit sounds normally considered faint or even unpleasant. In fact, in the field of motor vehicles, the electric motors used are normally those suitable for rotating at relatively high speeds, so as to limit the bulk and weight; as a result, the sounds produced have intensities that become relatively significant in the field of high frequencies. Thus, the sounds produced overall are perceived by the human ear as unpleasant whistles. This has a negative impact on the driver since the latter is less engaged in driving, less aware of the operating state of the motor, or even disturbed by the unpleasantness of the sounds. Therefore, there is a need to improve the quality of the sounds perceived by the driver of an electric vehicle, in particular with the aim of increasing the involvement and awareness of the driver with respect to the operating condition of the motor vehicle. US2021101480A1 discloses the preamble of claim 1. One purpose of the invention is to respond to the need identified above, preferably in a simple and reliable way. DESCRIPTION OF THE INVENTION The purpose is achieved with a propulsion apparatus according to claim 1. The dependent claims define particular embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS Below, embodiments of the invention are described to better understand the same by way of non-limiting examples and with reference to the attached drawings in which: Figure 1 is a perspective view of a motor vehicle comprising a propulsion apparatus according to the invention,Figure 2 is a perspective view, on an enlarged scale and with parts removed for clarity, of a portion of the propulsion apparatus,Figure 3 is a cross section of the propulsion apparatus according to a plane section defined by the line III-III in Figure 2,Figures 4, 5 are parts detailing the cross section in Figure 3 and correspond to two respective, distinct operating conditions of the propulsion apparatus,Figures 6, 7 are similar to Figures 4, 5, but with some elastic components represented in a schematic form,Figure 8 is a diagram of the positioning of some magnets of the propulsion apparatus,Figure 9 is a diagram of a variant of the positioning of Figure 8, andFigures 10-12 are diagrams of additional variants of the positioning in Figures 8, 9. EMBODIMENTS OF THE INVENTION In Figure 1, the reference number 1 is used to indicate, as a whole, a motor vehicle. Normally, the motor vehicle 1 has a body 2, multiple wheels 3, and a suspension assembly not illustrated and configured to suspend the body 2 with respect to the wheels 3. The wheels 3 represent known traction means for moving the motor vehicle 1, but for the purposes of the invention they could be replaced by any other suitable means, even unusual ones, like, for example, tracked means. The motor vehicle 1 also comprises an electric motor 5 for propelling the motor vehicle 1, as well as, in particular, a transmission assembly 6. The electric motor 5 is, thus, part of a propulsion apparatus of the motor vehicle 1. The electric motor 5 is configured to deliver mechanical power; the transmission assembly 6 is configured to transmit the mechanical power delivered to two of the wheels 3 to move the motor vehicle 1. The transmission assembly 6 could also be configured to transmit the mechanical power to all the wheels 3 or, more generally, to the traction means of the motor vehicle 1. Optionally, the transmission assembly 6 could also have the function of reducing the output speed of the motor 5, thus rotating the wheels 3 at a reduced rotation speed with respect to the output speed of the motor 5. During the operation of the motor 5, i.e. while the motor 5 delivers mechanical power, the same motor 5 emits a rotating magnetic field. More specifically, the motor 5 has a rotor 7 and a stator 8 coaxial to each other around a rotor axis R. Either the stator 8 or the rotor 7 is supplied with electric current, so that a magnetic interaction is created with magnetic elements of the other, either the stator 8 or the rotor 7. The magnetic interaction corresponds to the rotating magnetic field, which is the cause of a rotation of the rotor 7 with respect to the stator 8 around the rotor axis R. The magnetic principles linked to the operation of the electric motors are generally known, so they are not explained in further detail here. In particular, the generation of a rotating magnetic field by an electric motor is an underlying principle of the operation of the electric motor. The magnetic field generated by the motor 5 rotates around the rotor axis R, i.e., it follows the rotation direction of the ro