Device for influencing an exhaust gas flow

Abstract

A device for influencing an exhaust gas flow, in particular for controlling sound emission in an exhaust branch of an engine, has a closure member that is driven by a motor in the exhaust pipe. The closure member produces pressure pulsations in the exhaust gas, so that a so-called “sound design” is possible. A force-transmitting, thermal decoupling member is integrated into a force transmission member located between the drive motor and the closure member to interrupt the heat transfer between the closure member and the drive motor.

1 . A device for influencing an exhaust gas flow, in particular for controlling sound emission in an exhaust branch of an engine, comprising:
 a closure member movably arranged in an exhaust gas flow;   a driving device for the closure member, the driving device including a drive motor and a force transmission member to couple the drive motor to the closure member for drive, wherein the closure member offers different flow resistances to the exhaust gas flow depending on a position of the closure member in the exhaust gas flow; and   a force-transmitting, thermal decoupling member integrated into the force transmission member to interrupt heat transfer from the closure member to the drive motor via the force transmission member.   
   
   
       2 . The device according to  claim 1 , wherein the force-transmitting, thermal decoupling member divides the force transmission member thermally into a flow-side drive train and a motor-side drive train. 
   
   
       3 . The device according to  claim 1 , wherein the force-transmitting, thermal decoupling member has a lower thermal conductivity than a remaining force transmission member. 
   
   
       4 . The device according to  claim 1 , wherein the force-transmitting, thermal decoupling member has a thermal conductivity that is lower than an overall thermal conductivity of a remaining force transmission member at least by a factor of 3. 
   
   
       5 . The device according to  claim 1 , wherein the force-transmitting, thermal decoupling member transmits overall drive power to the closure member. 
   
   
       6 . The device according to  claim 1 , wherein the force-transmitting, thermal decoupling member is made of ceramic material or mica or has a hollow chamber structure. 
   
   
       7 . The device according to  claim 2 , wherein the force-transmitting, thermal decoupling member is part of a coupling which compensates for a positional and/or an angular offset of the flow-side and motor-side drive trains into which the force-transmitting, thermal decoupling member divides the force transmission member. 
   
   
       8 . The device according to  claim 1 , wherein the force transmission member is a directly driven rotating shaft. 
   
   
       9 . The device according to  claim 8 , wherein the directly driven rotating shaft is made of thermally insulating ceramic material at least on an outer surface in a section located outside of the exhaust gas flow. 
   
   
       10 . The device according to  claim 8 , wherein in a region of bearing, the directly driven rotating shaft has a ceramic coating applied thereon and rotating therewith. 
   
   
       11 . The device according to  claim 8 , wherein in a region of bearing, the directly driven rotating shaft has a bearing ring which is applied on the directly driven rotating shaft and rotates therewith and is connected with the directly driven rotating shaft by glazing. 
   
   
       12 . The device according to  claim 1 , wherein the drive motor moves the closure member with sufficient speed to generate pressure pulsations in the exhaust gas which lead to an audible sound emission. 
   
   
       13 . The device according to  claim 1 , wherein the closure member is a rotatable flap. 
   
   
       14 . The device according to  claim 13 , wherein a drive shaft of the drive motor is substantially coaxial to a rotation axis of the rotatable flap. 
   
   
       15 . The device according to  claim 1 , wherein the force-transmitting, thermal decoupling member has a thermal conductivity that is lower than an overall thermal conductivity of a remaining force transmission member at least by a factor of 5.