Charging device, more preferably exhaust gas turbocharger for a motor vehicle

Abstract

The invention relates to a charging device, such as an exhaust gas turbocharger for a motor vehicle, with a shaft carrying a compressor wheel, with a fixing device for fixing the compressor wheel on the shaft, with at least one component fixed on the shaft together with the compressor wheel by the fixing device. It can be achieved that heat expansion of the compressor wheel through the expansion coefficient (α 3 ) of at least one component can be at least partially offset. Because of this it is possible to increase the initial clamping force with which the components are positioned or clamped on the shaft without the permissible surface pressure for the clamp components being exceeded.

1 . An exhaust gas turbocharging device, comprising:
 a shaft carrying a compressor wheel;   a fixing element for fixing the compressor wheel on the shaft; and   at least one component fixed on the shaft together with the compressor wheel by the fixing device, wherein at least in a predetermined temperature range an expansion coefficient (α 3 ) of the at least one component is smaller than an expansion coefficient (α 1 ) of the compressor wheel.   
     
     
         2 . The exhaust gas turbocharging device according to  claim 1 , wherein in the predetermined temperature range an expansion coefficient (α 2 ) of the shaft is smaller than the expansion coefficient (α 1 ) of the compressor wheel. 
     
     
         3 . The exhaust gas turbocharging device according to  claim 1 , wherein in the predetermined temperature range the expansion coefficient (α 3 ) of the at least one component is smaller than the expansion coefficient (α 2 ) of the shaft. 
     
     
         4 . The exhaust gas turbocharging device according to  claim 1 , wherein the shaft is produced of at least one of a steel and a steel alloy. 
     
     
         5 . The exhaust gas turbocharging device according to  claim 1 , wherein the compressor wheel is produced of at least one of an aluminium, a titanium, an aluminium alloy and a titanium alloy. 
     
     
         6 . The exhaust gas turbocharging device according to  claim 1 , wherein the at least one component is designed of an alloy, and wherein because of the Invar effect of the alloy the expansion coefficient (α 3 ) of the at least one component is anomalously low. 
     
     
         7 . The exhaust gas turbocharging device according to  claim 1 , wherein the expansion coefficient (α 3 ) of the at least one component is at least one of approximately zero and negative. 
     
     
         8 . The exhaust gas turbocharging device according to  claim 1 , wherein at least one fixing element of the fixing device has an expansion coefficient (α f ) which is smaller than the expansion coefficient (α 1 ) of the compressor wheel. 
     
     
         9 . The exhaust gas turbocharging device according to  claim 8 , wherein the at least one fixing element has an expansion coefficient (α f ) that is smaller than the expansion coefficient (α 2 ) of the shaft section. 
     
     
         10 . The exhaust gas turbocharging device according to  claim 8  wherein the at least one fixing element is designed of an alloy wherein, because of the Invar effect of the alloy the expansion coefficient (α f ) of the at least one fixing element is anomalously low. 
     
     
         11 . The exhaust gas turbocharging device according to  claim 1 , wherein the at least one fixing element is designed as a shaft nut. 
     
     
         12 . The exhaust gas turbocharging device according to  claim 1 , wherein the at least one component is designed as at least one of a sealing bush, as a part of the sealing bush and as a thrust washer. 
     
     
         13 . The exhaust gas turbocharging device according to  claim 2 , wherein in the predetermined temperature range the expansion coefficient (α 3 ) of the at least one component is smaller than the expansion coefficient (α 2 ) of the shaft. 
     
     
         14 . The exhaust gas turbocharging device according to  claim 2 , wherein the shaft is produced of at least one of a steel and a steel alloy. 
     
     
         15 . The exhaust gas turbocharging device according to  claim 2 , wherein the compressor wheel is produced of at least one of an aluminium, a titanium, an aluminium alloy and a titanium alloy. 
     
     
         16 . The exhaust gas turbocharging device according to  claim 2 , wherein the at least one component is designed of an alloy, and wherein because of the Invar effect of the alloy the expansion coefficient (α 3 ) of the at least one component is anomalously low. 
     
     
         17 . The exhaust gas turbocharging device according to  claim 2 , wherein the expansion coefficient (α 3 ) of the at least one component is at least one of approximately zero and negative. 
     
     
         18 . The exhaust gas turbocharging device according to  claim 2 , wherein the at least one fixing element of the fixing device has an expansion coefficient (α f ) which is smaller than the expansion coefficient (α 1 ) of the compressor wheel. 
     
     
         19 . The exhaust gas turbocharging device according to  claim 2 , wherein the at least one such fixing element is designed as a shaft nut. 
     
     
         20 . The exhaust gas turbocharging device according to  claim 2 , wherein the at least one component is designed as at least one of a sealing bush, as a part of the sealing bush and as a thrust washer.