WO2018138079A1 - Antenna for an access system and/or hands-free start-up for a motor vehicle - Google Patents

Abstract

The present invention concerns an antenna (A1) for an access system and/or hands-free start-up for a motor vehicle, wherein the antenna (A1): - forms part of said motor vehicle and is a low-frequency antenna; - comprising: - at least two coils (B1, B2) connected in parallel, each coil (B1, B2) being suitable for being powered by a current (I1, I2), the sum of said currents (I1, I2) flowing in the coils (B1, B2) being equal to a total current (Itot); - and a support for the coils (B1, B2).

Description

 ANTENNA FOR HANDS-FREE ACCESS AND / OR STARTING SYSTEM FOR MOTOR VEHICLE

DOMAI N E TECH AND I NVENTION

 The present invention relates to an antenna for access system and / or hands-free startup for a motor vehicle.

 It finds a particular but non-limiting application in communications with an access identifier and / or hands-free startup for a motor vehicle.

I NVE NTIO N I NVE TIO N TECH NOLOGIC AR

 A hands-free access and / or start system known to those skilled in the art includes a hands-free access and / or start-up identifier and a low-frequency antenna arranged in the motor vehicle. The hands-free access and / or hands-free identification identifier worn by a user makes it possible to perform an automatic remote locking / unlocking function of an opening leaf of the motor vehicle and / or a starting function of the engine of the motor vehicle without user action on said access identifier and / or hands-free start. The access identifier and / or hands-free start communicates for this purpose with said low frequency antenna.

 A disadvantage of this state of the art is that for this hands-free access and / or start-up application, the current supplied to the low-frequency antenna of the motor vehicle is important and can lead to the generation of electroacoustic noise by said low frequency antenna that is audible by the human ear.

GENERAL DESCRIPTIONS OF THE I NVE NTIO N

 To this end, the invention proposes an antenna for access and / or hands-free starting system for a motor vehicle, according to which said antenna:

- is part of said motor vehicle and is a low frequency antenna; - includes:

 at least two coils connected in parallel, each coil being adapted to be supplied with a current, the sum of said currents flowing in said coils being equal to a total current;

 a support for said coils.

 Thus, as will be seen in more detail below, by increasing the number of coils in the antenna (compared to a conventional antenna comprising only one coil), the current flowing in each coil is decreased. to remove any acoustic noise.

 According to non-limiting embodiments, the antenna may further comprise one or more additional characteristics from the following.

 COPY CLAIM 2 and later B REVE DESCRI PTION OF FIG U RES

 The invention and its various applications will be better understood by reading the following description and examining the figures that accompany it.

 FIG. 1 represents an antenna for a motor vehicle according to the invention, said antenna being adapted to cooperate with a hands-free access and / or start identifier and comprising two coils according to a first non-limiting embodiment;

 FIG. 2 represents an electrical diagram of said antenna of FIG. 1 according to one nonlimiting embodiment;

 FIG. 3 represents an electrical diagram of an antenna for a motor vehicle according to the invention, said antenna being adapted to cooperate with a hands-free access and / or start identifier and comprising four coils according to a second embodiment non-limiting.

DESCRIPTIO N OF I NVE NTIO N REALI MODES The same elements, by structure or by function, appearing in different figures, unless otherwise specified, retain the same references.

 An antenna A1 for a motor vehicle V according to the invention is illustrated in Figures 1 to 3, according to non-limiting embodiments.

The antenna A1 is part of a SYS hands-free access and / or start-up system illustrated in FIG. 1, said hands-free access and / or start-up system comprising:

 a hands-free access and / or start unit U comprising said antenna A1 and an electronic control unit ECU; and

- a login and / or hands-free ID.

These different elements are described below.

 In the following description, the access ID and / or start hands-free ID is also called ID hands-free ID.

• Al antenna

The antenna A1 is a low frequency antenna. It is adapted to emit a low frequency signal SBF.

 In a non-limiting embodiment, the frequency of the low frequency antenna A1 is between 20 kHz and 150 kHz. In a nonlimiting variant embodiment, the frequency of the low frequency antenna A1 is equal to 125 kHz.

 The antenna A1 is part of the motor vehicle V. In a non-limiting embodiment, the antenna A1 is disposed inside the passenger compartment of the motor vehicle V. In non-limiting examples, the antenna A1 is arranged at the start button, at the steering column, on the dashboard, at the center console or next to the gear lever, in the dashboard, in the trunk, etc.

In another nonlimiting embodiment, the antenna A1 is disposed outside the passenger compartment of the motor vehicle V. In non-limiting examples, the antenna A1 is arranged in a bumper, in a door etc. . The A1 antenna is adapted to communicate with a hands-free ID. There is a strong current Itot, called total current especially when the antenna A1 communicates with a hands-free identifier ID. Indeed, when the antenna A1 communicates with a hands-free identifier ID, it must emit a magnetic field large enough to communicate with him and therefore be powered by a total current Itot strong enough for this purpose. Furthermore, this total current Itot is adapted to allow a sufficiently large magnetic field to be obtained so that the low frequency signal SBF emitted by the antenna A1 can not be disturbed by the surrounding electromagnetic noise. It will be noted that such electromagnetic noise may be generated by the other components of the motor vehicle V such as in non-limiting examples, calculators, a blower of a heating and / or air-conditioning device, etc.

The magnetic field indeed defines the communication distance of the antenna A1 with here the ID hands-free ID. In a non-limiting embodiment, the communication distance is between zero and five meters.

 Thanks to this magnetic field which is an electromagnetic wave, the antenna A1 can transmit a low frequency signal SBF to communicate with the hands-free identifier ID. The low frequency signal SBF is indeed propagated by the electromagnetic wave.

In a nonlimiting embodiment, said antenna A1 is adapted to transmit a low frequency signal SBF with an amplitude modulation of between 1 KHz and 20 KHz. In a nonlimiting variant embodiment, said antenna A1 is adapted to transmit a low frequency signal SBF with an amplitude modulation of 4KHz. This allows to have a sufficient information rate of 4kbauds as part of the application access and / or hands-free startup. In a non-limiting example, the low frequency signal SBF is transmitted at an amplitude modulation of 4KHz on a 125KHz carrier. In a first non-limiting embodiment, the total current Itot is of the order of 1 A (Ampere). This total current Itot is strong enough that the antenna A1 can communicate with a hands-free identifier ID.

In a second non-limiting embodiment, the total current Itot is of the order of 2A. This makes it possible to generate a magnetic field sufficient for the hands-free identifier ID to pick up and decode the low frequency signal. Indeed, electromagnetic noise generated by the other components of the motor vehicle can disrupt the communication between said access ID and / or ID hands-free ID and said antenna A1. In order to limit this disturbance, the total current Itot supplied to said antenna A1 is increased so as to increase the magnetic field generated by said antenna A1.

 As illustrated in FIG. 1, the antenna A1 comprises:

 at least two coils B;

a support for said N2 coils;

 a CO connector adapted to connect said antenna A1 to a wire bundle F.

 The elements are described in detail below.

 In a non-limiting embodiment, the support N2 is a magnetic core. In a non-limiting embodiment, the core N2 is a ferrite core.

 Each coil B is fed by a current I. Thus, a current I flows in each coil B so that the sum of said currents I flowing in said coils B is equal to the total current Itot. Having multiple coils in the antenna A1 reduces the current I flowing in each coil.

In a non-limiting embodiment, the current I flowing in each coil is less than or equal to 500 mA. This makes it possible to have no electroacoustic noise generated by each coil B and therefore generated by the antenna A1. Thus, a user of the motor vehicle V will not hear sound during the emission of the magnetic field by the antenna A1. We note that from 700mA, and for a low frequency SBF signal emitted at an amplitude modulation of 4KHz, the current flowing in a coil makes it vibrate. A sound wave propagates at the amplitude modulation frequency of the emitted signal that creates electroacoustic noise audible to the human ear. The acoustic noise is in fact proportional to the current flowing in an antenna, in particular in its coil. It is recalled that an audible sound is between 10Hz and 20kHz. It can be observed that the higher the amplitude modulation of the emitted signal, the greater the acoustic noise is in this case.

Thus, the same magnetic field is obtained as if the antenna A1 comprised only one coil, but without the disadvantages of acoustic noise. This does not reduce the transmission performance of the antenna A1.

 In a first nonlimiting embodiment illustrated in FIGS. 1 and 2, the antenna A1 comprises two coils B1, B2.

 The coils B1 and B2 are wound around the core N2. These are inductances. In Figure 2, the inductances are modeled. As illustrated in FIG. 2, the coils B1 and B2 are connected in parallel. They are connected at their end. The coil B1 is adapted to be powered by a first current 11 and the coil B2 is adapted to be supplied by a second current 12. The first current 11 and the second current 12 which flow in the two coils B1, B2 make it possible to generate a magnetic field. In a non-limiting embodiment, the first stream 11 and the second stream 12 are less than or equal to 500 mA. This allows the antenna A1 not to generate sound noise. This gives a total current Itot of 1 A and the same level of magnetic field as if the antenna A1 only included a single coil fed by a current of 1 A.

 In a second nonlimiting embodiment illustrated in FIG. 3, the antenna A1 comprises four coils B1, B2, B3, B4.

The coils B1, B2, B3, B4 are wound around the core N2. These are inductances. In Figure 3, the inductances are modeled. As illustrated in Figure 3, the coils B1, B2, B3, B4 are connected in parallel. They are connected at their end. The coil B1 is adapted to be fed by a first current 11, the coil B2 by a second current 12, the coil B3 by a third current 13 and the coil B4 by a fourth current 14. The first current 11, the second current 12 the third current 13 and the fourth current 14 which flow respectively in the coils B1, B2, B3, B4 make it possible to generate a magnetic field. In a non-limiting embodiment, the first stream 11 the second stream 12, the third stream 13 and the fourth stream 14 are less than or equal to 500mA. This allows the antenna A1 not to generate noise and moreover it allows the antenna A1 not to be disturbed by electromagnetic noise from other bodies of the motor vehicle. This gives a total current Itot of 2A and the same level of magnetic field as if the antenna A1 had only one coil fed by a current of 2A.

The wire harness F is connected to an ECU electronic control unit of the motor vehicle V. It supplies the antenna A1 with the total current Itot supplied by the ECU electronic control unit. · ECU_justice_just

 In a non-limiting embodiment, the electronic control unit ECU is the motor control of said motor vehicle V. Thus, the antenna A1 is connected via the connector CO to the engine control ECU.

As illustrated in FIG. 1, in a nonlimiting embodiment, the electronic control unit ECU is adapted to supply the total current Itot to the antenna A1, and the sum of the currents I in each coil B is equal to the current total Itot (as seen previously).

The electronic control unit ECU is adapted to cooperate with a battery (not shown) of the motor vehicle V. The battery supplies a direct current to the control unit ECU. The electronic control unit ECU converts the direct current of the battery into an alternating current adapted to the antenna A1. In a non-limiting example, the alternating current (which is the total current Itot) is provided at a frequency of 125 kHz as seen above. The ECU electronic control unit is thus adapted to control the antenna A1, namely it is adapted to provide the amount of current required for the antenna A1.

• Ldentjfjant jnains-JLbje_s_ÎQ

The ID hands-free ID comprises at least one antenna A2 (illustrated in Figures 2 and 3) adapted to communicate with the antenna A1 of the motor vehicle V. In non-limiting examples, the ID hands-free ID is a electronic key, a badge, a mobile phone, a smart mobile phone called "Smartphone" in English etc. In a non-limiting embodiment, the antenna A2 is a low frequency antenna. In a non-limiting embodiment, the ID hands-free identifier comprises three antennas A2 perpendicular to each other so as to be able to capture the entire magnetic field, regardless of the orientation of the ID hands-free ID.

 In a non-limiting embodiment, the ID hands-free identifier makes it possible to perform the function of access and / or start hands-free, called PEPS called in English "Passive Entry and Passive Start".

 Thus, the ID hands-free identifier makes it possible to perform the locking / unlocking function of the motor vehicle V also called a hands-free access function which is based on:

 a low frequency signal exchange SBF from the low frequency antenna A1 of the motor vehicle V to the hands-free identifier ID; and

- An exchange of high frequency signals (not shown) of the ID hands-free identifier to a dedicated hands-free computer of the automotive vehicle V. In a non-limiting embodiment, the high frequency signals are radio frequency signals. In a variant of non-limiting embodiment, the radiofrequency signals are transmitted at a frequency of 433 MHz.

When a person tries to open an opening (door, trunk, tailgate) of the motor vehicle V, for example by pulling on a handle of a door, the antenna A1 sends a low-frequency signal SBF to the identifier hands - free ID to authenticate. The hands-free identifier ID is authenticated by sending a high frequency signal to said vehicle V, in particular to its dedicated hands-free computer. If the authentication is validated the opening is unlocked.

The procedure of access to a motor vehicle via a hands-free identifier ID is well known to those skilled in the art, it is not described in detail here.

 In addition, in a non-limiting embodiment, the identifier hands-free ID makes it possible to perform the starting function of the motor vehicle V. When a person presses a start button for example, the antenna A1 sends a signal Low-frequency SBF to hands-free ID ID to authenticate it. The hands-free identifier ID is authenticated by sending a high frequency signal to said vehicle V, in particular to its dedicated hands-free calculator. If the authentication is validated the vehicle starts.

 The starting procedure for a motor vehicle via a hands-free identifier ID is well known to those skilled in the art, it is not described in detail here.

 Thus, the dedicated hands-free computer of the motor vehicle V is adapted to receive high frequency signals from the ID hands-free identifier and subsequently is adapted to:

 - authenticate the ID hands-free ID; and or

 - allow the locking / unlocking of the motor vehicle V; and or

- authorize the starting of the motor vehicle V.

In a non-limiting embodiment, the dedicated hands-free computer is the electronic control unit ECU. Of course, the description of the invention is not limited to the application, the embodiments and the examples described above. Thus, the ID hands-free identifier makes it possible to perform the access function only, or the start function only. Thus, the invention described has the following advantages:

- it is simple to implement;

 - it is inexpensive;

 it strongly limits the electroacoustic coupling in the antenna A1 and consequently it strongly limits the sound noise generated by the antenna A1 and audible by the human ear.

Claims

1. Antenna (A1) for access and / or hands-free start system (SYS) for a motor vehicle (V), according to which said antenna (A1):  - is part of said motor vehicle (V) and is a low frequency antenna;  - includes:  at least two coils (B) connected in parallel, each coil (B) being adapted to be supplied with a current (I), the sum of said currents (I) flowing in said coils (B) being equal to a total current ( Itot);  a support (N2) for said coils (B). 2. Antenna (A1) according to claim 1, according to said total current (Itot) is provided by an electronic control unit (ECU) of the motor vehicle (V). Antenna (A1) according to claim 1 or claim 2, wherein said antenna (A1) comprises two coils (B1, B2). 4. Antenna (A1) according to claim 1 or claim 2, wherein said antenna (A1) comprises four coils (B1, B2, B3, B4). 5. Antenna (A1) according to any one of claims 1 to 4, wherein the current (I) flowing in each coil (B) is less than or equal to 500 milliamps. 6. Antenna (A1) according to any one of claims 1 to 5, wherein said antenna (A1) is adapted to emit a low frequency signal (SBF) with an amplitude modulation between 1 kHz and 20 kHz. 7. Antenna (A1) according to any one of claims 1 to 6, wherein said antenna (A1) is adapted to emit a low frequency signal (SBF) with an amplitude modulation of 4kHz. 8. Antenna (A1) according to any one of claims 1 to 7, wherein said antenna (A1) is adapted to cooperate with an access identifier and / or hands-free startup (ID) for a motor vehicle (V) . 9. Access unit and / or hands-free start (U) for a motor vehicle (V) comprising an antenna (A1) according to any one of claims 1 to 8 above. 10. The access and / or hands-free start unit (U) according to claim 9, wherein said access and / or hands-free start unit (U) further comprises a suitable electronic control unit (ECU). to supply a total current (Itot) to said antenna (A1). 1 1. System for access and / or hands-free startup (SYS), according to which said system for access and / or hands-free startup (SYS) comprises:  a hands-free access and / or start unit (U) comprising:  an antenna (A1) according to any one of the preceding claims 1 to 8;  an electronic control unit (ECU) adapted to supply a total current (Itot) to said antenna (A1);  a hands-free access and / or hands-free identifier (ID) comprising at least one antenna (A2) adapted to communicate with said antenna (A1) for a motor vehicle (V).