Engine sound enhancement system of a vehicle

1. A sound enhancement system for an engine of a vehicle, the vehicle having a compartment for a driver and a passenger, the engine having a casing, the sound enhancement system comprising:

a sound sensor that senses a sound of the engine and generates an electrical signal indicative of the sensed sound,

a signal processor connected to said sound sensor so as to process the electrical signal to generate an output audio sound; and

a speaker adapted to be disposed in the vehicle compartment, wherein said speaker is connected to said signal processor so as to receive the output audio sound and to generate an enhancement sound relative to the sound of the engine, wherein said sound sensor is a vibration sensor adapted to be disposed on the casing of the engine to detect vibrations of the engine casing that generate the sound of the engine and wherein the electrical signal is a vibration signal of the engine casing, and wherein said vibration sensor is a shaker or an exciter-type mechanical electrical transducer that has a fixed part firmly coupled to the engine casing and a mobile part that moves with respect to the fixed part when the engine casing has a vibration alteration so that the vibration sensor can detect a vibration speed of the engine casing, said vibration sensor acting as an accelerometer integrator or a velocimeter.

2. The sound enhancement system of claim 1 , wherein said vibration sensor comprises a centering element acting as an elastic suspension, said centering element comprising an external ring connected to the said mobile part, an internal ring connected to said fixed part and a plurality of elastic spokes connecting said external ring with said internal ring.

3. The sound enhancement system of claim 1 , comprising a CAN (Controller Area Network) interface adapted to be connected to a CAN-bus of the vehicle and connected to said signal processor, said CAN interface being configured to detect engine revolution and torque values and to send the values to said signal processor such that said signal processor uses the values to control a gain of the output audio signal.

4. The sound enhancement system of claim 3 , wherein said signal processor comprises an array of dynamic filters connected to said vibration sensor and to said CAN interface, each filter of said array of dynamic filters having a preset frequency and a variable gain according to the engine revolution and torque values detected by said CAN interface.

5. The sound enhancement system of claim 3 , wherein said signal processor comprises an overall gain block connected to said vibration sensor and to said CAN interface, said overall gain block being configured to apply an overall gain to the electrical signal detected by said vibration sensor according to the engine revolution and torque values detected by said CAN interface.

6. The sound enhancement system of claim 5 , wherein said signal processor comprises an array of dynamic filters connected to said overall gain block and to said CAN interface, said array of dynamic filters comprising a plurality of filter arrays, wherein each filter array of said plurality of filter arrays is associated with a specific overall gain of said overall gain block, each filter having a preset fixed frequency and a variable gain according to the engine revolution and torque values detected by said CAN interface.

7. The sound enhancement system of claim 5 , wherein said CAN interface is configured to detect from said CAN-bus a vehicle attitude value set by the driver from at least two vehicle attitude values, wherein said overall gain block contains a number of three-dimensional look-up tables equal to a number of vehicle attitudes that are set by the driver, wherein each three-dimensional look-up table has engine revolution values as an X axis, torque values as a Y axis and overall gain values as a Z axis.

8. The sound enhancement system of claim 1 , wherein said signal processor comprises a mixer that mixes the electrical signal detected by said vibration sensor with an audio signal coming from an audio multi-channel power amplifier of the vehicle.

9. The sound enhancement system of claim 8 , wherein said signal processor comprises a gain adjustment block connected to said mixer to set a gain of said audio signal from the audio multi-channel power amplifier.

10. The sound enhancement system of claim 1 , wherein the vehicle has an audio system with a multichannel power amplifier connected to a plurality of speakers disposed in the vehicle compartment, wherein said speaker emitting the engine sound enhancement is a central speaker of said vehicle audio system.