Active exhaust-noise attenuation muffler

Abstract

An active exhaust-noise attenuation muffler for an exhaust pipe includes a control unit, a sensor assembly which is operatively connected to the control unit, and a gas-tight diaphragm constructed to be resistant to exhaust gas in the exhaust pipe and acoustically coupled with a flow of exhaust gas in the exhaust pipe. The diaphragm has a surface which confronts the exhaust gas. A transducer is operated by the control unit for causing the surface of the diaphragm to vibrate in a bending vibration mode to produce a structure-borne sound in dependence on exhaust noise.

1 . An active exhaust-noise attenuation muffler for an exhaust pipe, comprising: 
 a control unit;    a sensor assembly operatively connected to the control unit;    a gas-tight diaphragm constructed to be resistant to exhaust gas in an exhaust pipe and acoustically coupled with a flow of exhaust gas in the exhaust pipe, said diaphragm having a surface which confronts the exhaust gas; and    a transducer operated by the control unit for causing the surface of the diaphragm to vibrate in a bending vibration mode to produce a structure-borne sound in dependence on exhaust noise.    
   
   
       2 . The exhaust-noise attenuation muffler of  claim 1 , wherein the diaphragm is disposed in an opening in a wall of the exhaust pipe.  
   
   
       3 . The exhaust-noise attenuation muffler of  claim 1 , further comprising a resonator received in an opening in a wall of the exhaust pipe, wherein the diaphragm is operatively connected to the resonator at a distance to the opening.  
   
   
       4 . The exhaust-noise attenuation muffler of  claim 1 , wherein the diaphragm is flat.  
   
   
       5 . The exhaust-noise attenuation muffler of  claim 1 , wherein the diaphragm is configured to conform to a contour of a wall of the exhaust pipe.  
   
   
       6 . The exhaust-noise attenuation muffler of  claim 1 , wherein the surface of the diaphragm is coated with metal through a vapor deposition process.  
   
   
       7 . The exhaust-noise attenuation muffler of  claim 1 , further comprising a stainless steel foil applied upon the surface of the diaphragm.  
   
   
       8 . The exhaust-noise attenuation muffler of  claim 1 , further comprising an electronic motor control system operatively connected to the control unit.  
   
   
       9 . The exhaust-noise attenuation muffler of  claim 1 , wherein the sensor assembly includes a temperature sensor for measuring a temperature of the exhaust gas in the exhaust pipe.  
   
   
       10 . The exhaust-noise attenuation muffler of  claim 1 , wherein the sensor assembly includes a throttle sensor for determining a throttle position.  
   
   
       11 . The exhaust-noise attenuation muffler of  claim 1 , wherein the sensor assembly includes a speed sensor for determining a motor speed.  
   
   
       12 . The exhaust-noise attenuation muffler of  claim 1 , wherein the sensor assembly includes a pressure sensor for determining the exhaust noise in the exhaust pipe.  
   
   
       13 . The exhaust-noise attenuation muffler of  claim 12 , wherein the pressure sensor is a microphone.  
   
   
       14 . The exhaust-noise attenuation muffler of  claim 1 , further comprising a microprocessor for controlling the control unit.  
   
   
       15 . The exhaust-noise attenuation muffler of  claim 1 , wherein the control unit includes an amplifier for boosting a signal received from the sensor assembly.  
   
   
       16 . The exhaust-noise attenuation muffler of  claim 1 , wherein the control unit is constructed to allow adjustment of a control performance.  
   
   
       17 . The exhaust-noise attenuation muffler of  claim 1 , wherein the transducer is an oscillation coil.  
   
   
       18 . The exhaust-noise attenuation muffler of  claim 1 , wherein the transducer is constructed to be heat-resistant.  
   
   
       19 . The exhaust-noise attenuation muffler of  claim 1 , further comprising a housing for accommodating the diaphragm and the transducer.  
   
   
       20 . The exhaust-noise attenuation muffler of  claim 20 , wherein the housing is disposed on an exhaust-distal side of the diaphragm in surrounding relationship to the transducer.  
   
   
       21 . The exhaust-noise attenuation muffler of  claim 1 , wherein the transducer is secured to a reverse side of the diaphragm.  
   
   
       22 . The exhaust-noise attenuation muffler of  claim 1 , wherein the compensation sound is 180° phase-shifted to the exhaust noise.