Patent Description:
Noise is generally undesirable, and various measures are taken to reduce noise. Such measures include arranging noise shielding material around a noise source to passively block or absorb noise, and to actively cancel noise using microphones to pick up a noise signal and speakers to emit an anti-phase signal. In the context of noise emitted by a noise source comprised in a vehicle, active noise cancelation is known to take place inside the cabin and may reduce the noise affecting the driver and/or passengers, but not the noise emitted to the environment. It would be desirable to provide for a reduction of the noise emitted from a noise source comprised in a vehicle to the environment.

<CIT> discloses an active vibration noise suppression apparatus including a solenoid mounted on the wheel housing, a reference signal detector on the knuckle, and a microphone disposed in the vehicle interior.

<CIT> relates to a vibration reducing device where sound is picked up by microphones, and noise cancelling sound is output by speakers.

<CIT> relates to an active vibration or noise suppression system capable of converging vibration or noise more quickly.

<CIT> relates to a vibration damping system for a vehicle includes a vibration sensor which detects vibration of a particular vibrating element. an actuator which applies vibration to the particular vibrating element and a controller which receives a vibration signal output from the vibration sensor and controls the actuator to apply to the particular vibrating element such vibration that damps the vibration detected by the vibration sensor.

According to a first aspect of the disclosure, there is provided a noise emission reduction system as defined by claim <NUM>.

The controller is configured to determine the control signal in such a way that the control signal results in the solenoid inducing vibration of the shielding member substantially in anti-phase with the sound emitted by the noise source, when the solenoid is coupled to the shielding member and to the frame. A technical benefit may include to more efficiently reduce the emission of noise from the system (such as vehicle) including the noise source.

In some examples, the controller may comprise: difference signal providing circuitry coupled to the accelerometer to receive the first signal from the accelerometer and to the microphone to receive the second signal from the microphone, and configured to provide a difference signal indicative of a difference between second signal and the first signal; and a signal processor coupled to the difference signal providing circuitry, and configured to: determine the control signal based on difference signal; and provide the control signal to the solenoid. A technical benefit may include that the difference signal may be indicative of an acoustic spectrum of the noise in relation to the reference frame of the vehicle, so that an effective control signal can relatively easily be provided. This may provide for a more robust noise emission reduction system.

In some examples, the microphone may be arrangeable between the noise source and the shielding member. A technical benefit may include to enable acquisition of undisturbed noise, providing for an improved determination of the control signal.

In some examples, the solenoid may be a linear solenoid having a first end connectable to the shielding member, and a second end couplable to the frame, the solenoid being controllable to linearly move the first end in relation to the second end. A technical benefit may include to provide for improved induction of vibration of the shielding member in relation to the frame.

The noise emission reduction system comprises the shielding member. A technical benefit may include to facilitate installation of the noise emission reduction system in a vehicle.

In some examples, the solenoid may be coupled to the shielding member at a center of mass of the shielding member. A technical benefit may include to provide for improved control by the solenoid of the vibration of the shielding member.

The shielding member comprises a sound dampening material. A technical benefit may include to additionally provide for passive reduction of noise emission, resulting in improved overall noise emission reduction.

The shielding member is a sandwich construction comprising metal sheets and sound dampening material arranged between the metal sheets. A technical benefit may include to provide passive reduction of noise emission as well as to provide for sufficient rigidity to enable efficient induced vibration of the shielding member. The provision of a relatively large shielding member may be provided for, which may provide for a cost-efficient system.

In some examples, the noise emission reduction system may comprise a plurality of solenoids, each being couplable between a shielding member of a plurality of shielding members and the frame of the vehicle; and the controller may be coupled to each solenoid of the plurality of solenoids, and configured to control each solenoid using a control signal determined for that solenoid. A technical benefit may include to increase the efficiency of the noise emission reduction. For instance, shielding members can be vibrated in different directions, enabling more efficient noise emission reduction in these different directions.

In some examples, the noise emission reduction system may comprise a plurality of microphones arrangeable to receive sound emitted by the noise source in different directions; and the controller may be coupled to each microphone of the plurality of microphones, and configured to: receive, from each microphone of the plurality of microphones, a second signal indicative of the sound received by that microphone, resulting in a plurality of second signals; and determine the control signal for the solenoid based on at least one of the second signals in the plurality of second signals. A technical benefit may include to increase the efficiency of the noise emission reduction. For instance, noise can be picked up from different directions, enabling more efficient noise emission reduction in these different directions.

In some examples, the noise emission reduction system may comprise a sheet-shaped shielding member at least partly surrounding an internal combustion engine comprised in a heavy vehicle; a linear push pull solenoid having a first end connected to the sheet-shaped shielding member, and a second end coupled to a frame of the heavy vehicle, and being controllable to induce vibration of the sheet-shaped shielding member in relation to the frame of the heavy vehicle; a microphone arranged between the internal combustion engine and the sheet-shaped shielding member; an accelerometer coupled to the frame; and a controller coupled to the linear push pull solenoid, to the microphone, and to the accelerometer, the controller being configured to: receive a first signal from the accelerometer; receive a second signal from the microphone; determine a control signal for the solenoid based on the first signal and the second signal; and control the solenoid using the determined control signal to induce vibration of the sheet-shaped shielding member, wherein the induced vibration of the shielding member is substantially in anti-phase with the sound emitted by the internal combustion engine.

The noise emission reduction system according to the first aspect of the disclosure may be included in a vehicle, further comprising a frame, a noise source, and a shielding member. The noise source may, for example, comprise an internal combustion engine, and/or a transmission, and/or an engine after treatment system.

According to a second aspect of the disclosure, there is provided a method as defined by claim <NUM>.

In some examples, the method may further comprise determining, by the controller, a control signal for the solenoid based on the first signal and the second signal; and the solenoid may be controlled using the control signal for the solenoid.

In some examples, the method may further comprise providing a difference signal indicative of a difference between second signal and the first signal; and determining the control signal based on difference signal.

The solenoid is controlled to induce vibration of the shielding member that is substantially in anti-phase with the sound emitted by the noise source.

In view of various national regulations, as well as a desire to reduce noise pollution in general, it would be desirable to provide for a reduction of the noise emitted from a noise source comprised in a vehicle to the environment.

<FIG> is an exemplary vehicle <NUM> according to one example. As is schematically shown in <FIG>, the vehicle <NUM>, here in the form of a truck, comprises a frame <NUM>, a noise source <NUM>, here exemplified by the internal combustion engine of the vehicle <NUM>, and a noise emission reduction system <NUM>.

<FIG> is an exemplary noise emission reduction system <NUM> according to one example. The noise emission reduction system <NUM> comprises a solenoid <NUM> a microphone <NUM>, an accelerometer <NUM>, and a controller <NUM>. The solenoid <NUM> is coupled to a shielding member <NUM> configured to at least partly surround a noise source <NUM>, and to a frame <NUM> being a reference structure for the noise emission reduction system <NUM>. The solenoid <NUM> is controllable to induce vibration of the shielding member <NUM> in relation to the frame <NUM>, when the solenoid <NUM> is coupled to the shielding member <NUM> and to the frame <NUM>. The microphone <NUM> is configured to receive sound emitted by the noise source <NUM>. The accelerometer <NUM> is couplable to the frame <NUM>. The controller <NUM> is coupled to the solenoid <NUM>, to the microphone <NUM>, and to the accelerometer <NUM>, and is configured to receive a first signal S1 from the accelerometer <NUM>, receive a second signal S2 from the microphone <NUM>, determine a control signal Sc for the solenoid <NUM> based on the first signal S1 and the second signal S2, and control the solenoid <NUM> using the determined control signal Sc to induce vibration of the shielding member <NUM> in relation to the frame <NUM>, when the solenoid <NUM> is coupled to the shielding member <NUM> and to the frame <NUM>. The microphone <NUM> may be configured to be arranged between the noise source <NUM> and the shielding member. As is schematically indicated in <FIG>, the noise emission reduction system <NUM> may optionally include at least one external microphone <NUM> configured to be arranged outside the shielding member <NUM>, in relation to the noise source <NUM>. Optionally, the controller <NUM> may be configured to additionally receive a signal from the external microphone <NUM>, and to determine the control signal Sc additionally based on the signal from the external microphone <NUM>. The first signal S1 from the accelerometer <NUM> may be indicative of vibration of the frame <NUM>, and the second signal S2 from the microphone <NUM> may be indicative of the noise emitted by the noise source <NUM>. By controlling the solenoid <NUM> using the determined control signal Sc to induce vibration of the shielding member <NUM> in relation to the frame <NUM>, a vibration component of the shielding member <NUM> induced by the noise emitted by the noise source <NUM> can be at least partly canceled out. By making the control signal Sc dependent on the first signal S1 from the accelerometer <NUM>, efficient noise cancellation can be achieved even though the frame <NUM> is itself in vibration.

<FIG> is an exemplary noise emission reduction system <NUM> according to one example. The controller <NUM> of the noise emission reduction system <NUM> according to this example comprises difference signal providing circuitry <NUM> and a signal processor <NUM>. The difference signal providing circuitry <NUM> is coupled to the accelerometer <NUM> to receive the first signal S1 from the accelerometer <NUM> and to the microphone <NUM> to receive the second signal S2 from the microphone <NUM>. The difference signal providing circuitry <NUM> is configured to provide a difference signal Sd indicative of a difference between the second signal S2 and the first signal S1. The signal processor <NUM> is coupled to the difference signal providing circuitry <NUM>, and configured to determine the control signal Sc based on difference signal Sd; and provide the control signal Sc to the solenoid <NUM>.

<FIG> is an exemplary noise emission reduction system <NUM> according to one example. As is schematically indicated in <FIG>, the noise emission reduction system <NUM> according to this example comprises a first sheet-shaped shielding member 9a, a second sheet-shaped shielding member 9b, and a third sheet-shaped shielding member 9c, first 11a, second 11b, and third 11c linear push pull solenoids, first 13a, second 13b, third 13c, fourth 13d, fifth 13e, and sixth 13f internal microphones, first 15a, second 15b, and third 15c accelerometers, a controller <NUM>, and optionally at least one external microphone <NUM>.

Each push pull solenoid 11a-c has a first end 25a (only indicated in <FIG> for one of the linear push pull solenoids 11a in order not to clutter the drawing) connected to its respective sheet-shaped shielding member 9a-c and a second end 25b coupled to the frame - here the upper part 3c of the frame, shown to be connected to right 3a and left 3b beams of the frame assembly. In the schematically illustrated example in <FIG>, the first 9a and third 9c sheet-shaped shielding members - the side shielding members - are further coupled to the frame (the beams 3a-b of the frame assembly) by flexible members <NUM>, such as springs or dampers. Although not explicitly shown in <FIG>, it should be noted that the second sheet-shaped shielding member 9b - the upper shield member - may be coupled to the upper part 3c of the frame assembly and/or to the first 9a and third 9c sheet-shaped shielding members by similar flexible members.

To combine rigidity with passive sound absorbing properties, the sheet-shaped shielding members 9a-c (or selected ones of the shielding members 9a-c) may be a sandwich construction comprising metal sheets 29a-b and sound dampening material <NUM> arranged between the metal sheets 29a-b. The sound dampening material <NUM> may, for example, comprise steel wool. The sandwich construction may allow forming a relatively large sheet-shaped shielding member 9a-c, that is still capable of being vibrated uniformly by a solenoid or solenoids.

As is schematically shown in <FIG>, the controller <NUM> is coupled to the solenoids 11a-c, to the internal microphones 13a-f, to the accelerometers 15a-c, and - optionally - to the external microphone <NUM>. The controller <NUM> is configured to receive a respective first signal from each of the accelerometers 15a-c, to receive a respective second signal from each of the internal microphones 13a-f, to optionally receive a third signal from the external microphone <NUM>, to determine a respective control signal for each of the solenoids 11a-c, based on the first signal, the second signal, and - optionally - the third signal, and to control the solenoids 11a-c using the determined control signal. The control signal is determined to cause vibration of each of the sheet-shaped shielding members 9a-c, in relation to the frame <NUM>, so that the resulting vibration of each of the sheet-shaped shielding members 9a-c is substantially in anti-phase with the sound emitted by the noise source (internal combustion engine, and/or transmission, and/or engine after treatment system).

<FIG> is a flow-chart illustrating an exemplary method according to an example. Referring to <FIG>, the method comprises receiving <NUM>, by a controller <NUM> from an accelerometer <NUM> coupled to a frame <NUM> of a vehicle <NUM>, a first signal S1 indicative of vibration of the frame, receiving <NUM>, by the controller <NUM> from a microphone <NUM> arranged to receive sound emitted by a noise source <NUM>, a second signal S2 indicative of the sound emitted by the noise source; and controlling <NUM>, by the controller <NUM>, based on the first signal S1 and the second signal S2, a solenoid <NUM> coupled to the frame <NUM> of the vehicle and to the shielding member <NUM> to induce vibration of the shielding member in relation to the frame of the vehicle.

Claim 1:
A noise emission reduction system (<NUM>) comprising:
a shielding member (<NUM>) configured to at least partly surround a noise source (<NUM>) comprised in a vehicle (<NUM>), the shielding member (<NUM>) being a sandwich construction comprising metal sheets (29a-b) and sound dampening material (<NUM>) arranged between the metal sheets;
a solenoid (<NUM>) couplable to the shielding member (<NUM>), and to a frame (<NUM>) of the vehicle (<NUM>), the solenoid (<NUM>) being controllable to induce vibration of the shielding member in relation to the frame of the vehicle, when the solenoid (<NUM>) is coupled to the shielding member (<NUM>) and to the frame (<NUM>);
a microphone (<NUM>) configured to receive sound emitted by the noise source (<NUM>);
an accelerometer (<NUM>) couplable to the frame (<NUM>); and
a controller (<NUM>) coupled to the solenoid (<NUM>), to the microphone (<NUM>), and to the accelerometer (<NUM>), the controller being configured to:
receive a first signal (S1) from the accelerometer (<NUM>);
receive a second signal (S2) from the microphone (<NUM>);
determine a control signal (Sc) for the solenoid (<NUM>) based on the first signal (S1) and the second signal (S2); and
control the solenoid (<NUM>) using the determined control signal (Sc) to induce vibration of the shielding member (<NUM>) in relation to the frame (<NUM>), when the solenoid (<NUM>) is coupled to the shielding member (<NUM>) and to the frame (<NUM>),
wherein the controller (<NUM>) is configured to determine the control signal (Sc) in such a way that the control signal (Sc) results in the solenoid (<NUM>) inducing vibration of the shielding member (<NUM>) substantially in anti-phase with the sound emitted by the noise source (<NUM>), when the solenoid (<NUM>) is coupled to the shielding member (<NUM>) and to the frame (<NUM>).