US 5,408,532 AGranted

Vehicle internal noise reduction system

AssigneeFuji Jokogyo Kabushiki Kaisha

InventorsKeitaro Yokota, Manpei Tamamura, Eiji Shibata, Hiroshi Iitaka

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Abstract

An ignition pulse shaped and demultiplied is used as a primary source and this primary source is converted into a canceling signal after being subjected to the sum of convolution products process with filter coefficients of an adaptive filter. Further the canceling signal is converted into a canceling sound by a speaker and outputted to the passenger compartment to cancel a vibration noise at a noise receiving point. The state of noise reduction is detected as an error signal by a microphone and the error signal is inputted to an exponential averaging circuit where the error signal is exponentially averaged with previous error signals by a trigger signal of the primary source from a trigger signal generating circuit. The error signal, as a result of this averaging, is compressed and then outputted to a LMS operational circuit. In the LMS operational circuit the filter coefficients are updated based on the primary source inputted via a C.sub.MNO circuit and the compressed error signal.

Claims15

Dependent claims

An internal noise reduction system for an automobile vehicle, the vehicle having, an internal combustion engine mounted on said vehicle, the engine including, an ignition coil for generating at least one ignition pulse signal within one engine cycle, a fuel injector for injecting fuel into a cylinder and an electronic control unit (ECU) for generating at least one fuel injection pulse signal within one engine cycle, the improvement of the system which comprises:

input signal transforming means responsive to said ignition pulse signal for transforming said ignition pulse signal into a single vibration noise source signal (primary source) so as to obtain a frequency spectrum composed of 0.5.times.n order components;
canceling signal synthesizing means responsive to said vibration noise source signal for synthesizing the transformed vibration noise source signal into a canceling signal based on filter coefficients of an adaptive filter and for outputting the synthesized canceling signal;
canceling sound generating means responsive to the synthesized canceling signal for generating a canceling sound to cancel a vibration noise in a passenger compartment of said vehicle;
error signal detecting means for detecting a reduced sound as an error signal at an noise receiving point;
noise components compressing means responsive to said vibration noise source signal for compressing said error signal so as to reduce an influence of random noise components other than noises to be reduced contained in said error signal;
and
coefficients updating means responsive to said vibration noise source signal and the compressed error signal for updating said filter coefficients of said adaptive filter.

4 more elements

Dependencies are inferred from the claim text.