Exhaust-gas energy recovery system and method for exhaust-gas energy recovery

Abstract

The invention relates to an exhaust-gas energy recovery system, comprising an exhaust-gas line system ( 111 ) for conducting exhaust gases of an internal combustion engine and comprising a motor-generator device ( 101 ), which can be driven by means of exhaust-gas energy in order to produce electric current. The exhaust-gas line system ( 111 ) comprises a first line arm ( 124 ) to the motor-generator device ( 101 ) for conducting exhaust gases into the motor-generator device ( 101 ). The motor-generator device comprises a motor ( 100 ), which is arranged in such a way that the motor can be driven by a pressure of exhaust gas flowing through the motor. The invention further relates to a corresponding method for exhaust-gas energy recovery.

1 . An exhaust gas energy recovery system comprising:
 an exhaust line system ( 111 ) for guiding exhaust gases from a combustion engine,   a motor/generator unit configured to be driven by exhaust energy to generate electrical energy,   wherein the exhaust line system comprises a first line arm to the motor/generator unit for guiding exhaust gases to the motor/generator unit,   wherein the motor/generator unit comprises a motor which is arranged to be driven by a pressure of passing exhaust gases, and   wherein the motor is a rotary engine comprising:
 a housing defining an inner room, 
 at least two rotary pistons arranged in the inner room, 
 an inlet opening which is connected with the exhaust line system for introducing the exhaust gases into the inner room, and 
 an outlet opening for the exhaust gas defined at the inner room at a side opposite to the inlet opening, 
 wherein each rotary piston comprises a gear rim at its outer circumference, and 
 the rotary pistons are arranged such that their gear rims mesh. 
   
     
     
         2 . The exhaust gas energy recovery system as defined in  claim 1 , further comprising:
 a combustion engine and an exhaust gas treatment system for cleaning exhaust gases,   wherein the exhaust line system is configured for guiding at least a part of the exhaust gases of the combustion engine first through the motor of the motor/generator unit and then to the exhaust gas treatment system.   
     
     
         3 . The exhaust gas energy recovery system as defined in  claim 1 , wherein the exhaust line system comprises a fork from which a first line arm runs via the motor in the direction of the exhaust gas treatment system and a second line arm bypasses the motor; and runs in the direction of the exhaust gas treatment system, and
 wherein the exhaust gas energy recovery system further comprises a control device at the fork configured to set proportions in which the exhaust gas in divided to the first and second line arms.   
     
     
         4 . The exhaust gas energy recovery system as defined in  claim 1 , wherein the control device comprises a rotatable shutter, and wherein a rotation position of the rotatable shutter determines in which parts the exhaust gas in guided into the first line arm and the second line arm. 
     
     
         5 . The exhaust gas energy recovery system as defined in  claim 1 , further comprising:
 two rotary pistons, wherein each rotary piston comprises at least two sealing strips; and at least two recesses at its outer circumference, the shapes of the recesses; and the sealing strips are chosen for sealing engagement of the sealing strips of each one of the rotary pistons with the recesses of the respective other rotary piston,   wherein the sealing strips are sized to sealingly contact a housing inner surface in a radial direction.   
     
     
         6 . The exhaust gas energy recovery system as defined in  claim 5 , wherein the sealing strips comprise a deformable material such that the sealing strips can be pressed against the housing inner surface by incoming exhaust gases. 
     
     
         7 . The exhaust gas energy recovery system as defined in  claim 5 , wherein each of the sealing strips comprises an exhaust gas contact surface facing inflowing exhaust gas when the respective rotary piston is at a rotation angle position at which said sealing strip contacts the housing inner surface ( 12 ), and
 wherein the exhaust gas contact surface has a concave shape.   
     
     
         8 . The exhaust gas energy recovery system as defined in  claim 7 , wherein each of the sealing strips has a rear side which is opposite the exhaust gas contact surface and which does not face inflowing exhaust gas when the respective rotary piston is at a rotation angle position in which said sealing strip contacts the housing inner surface, and
 wherein the rear side has a convex shape.   
     
     
         9 . The exhaust gas energy recovery system as defined in  claim 5 , wherein the rotary pistons comprise at their respective outer circumference slots for receiving and securing the sealing strips, and
 wherein the sealing strips are formed as slot nuts for securely coupling with the slots of the respective rotary piston.   
     
     
         10 . The exhaust gas energy recovery system as defined in  claim 9 , wherein the slots are formed as T-slots and each slot nut comprises a laterally protruding shroud for engaging with one of the T-slots. 
     
     
         11 . The exhaust gas energy recovery system as defined in  claim 5 , wherein each rotary piston comprises exactly two sealing strips at opposite angle positions at its outer circumference, and
 wherein each rotary piston comprises exactly two recesses arranged at the outer circumference at angle positions which are each offset by 90° relative to the angle positions of the two sealing strips.   
     
     
         12 . The exhaust gas energy recovery system as defined in  claim 1 , wherein the sealing strips protrude from their respective rotary piston further outwards in a radial direction than the respective gear rim. 
     
     
         13 . A method for exhaust gas energy recovery, the method comprising
 generating electrical energy from exhaust energy with a motor/generator unit, by: guiding exhaust gases to the motor/generator unit via a first line arm of an exhaust line system ( 111 ),   wherein the motor/generator unit comprises a motor which is driven by a pressure of passing exhaust gases,   wherein the motor is a rotary engine comprising:
 a housing defining an inner room, 
 at least two rotary pistons arranged in the inner room, 
 an inlet opening through which exhaust gases are transported from the exhaust line system into the inner room, and 
 an outlet opening for the exhaust gas defined at the inner room at a side opposite to the inlet opening, 
 each rotary piston comprises a gear rim at its outer circumference, and 
 the rotary pistons are arranged such that their gear rims mesh.