Injection nozzle

Abstract

An injection nozzle for an internal combustion engine, having a first nozzle needle for controlling the fuel injection through a first injection port, a second nozzle needle for controlling the fuel injection through a second injection port, a first control chamber in which a first control face drive-coupled to the second nozzle needle for introducing closing forces is disposed, and a control line for controlling the pressure in the first control chamber. Especially exact instants of the end of injection can be attained if in the first control chamber, a second control face is disposed that is drive-coupled to the first nozzle needle; a first coupling path connects the first control chamber directly or indirectly to a pressure source; a second coupling path connects the first control chamber directly or indirectly to the pressure source; and the second coupling path is controlled as a function of the stroke of the first nozzle needle such that it is blocked beyond a prestroke of the first nozzle needle.

1 . An injection nozzle for an internal combustion engine, comprising 
 a needle body ( 2 ), having at least one first injection port ( 5 ) and at least one second injection port ( 6 ),    a first nozzle needle ( 7 ), embodied as a hollow needle, with which the injection of fuel through the at least one first injection port ( 5 ) can be controlled,    a second nozzle needle ( 19 ), disposed coaxially to the first nozzle needle ( 7 ), with which the injection of fuel to the at least one second injection port ( 6 ) can be controlled,    a first control chamber ( 28 ), in which a first control face ( 29 ) embodied at or drive-coupled with the second nozzle needle ( 19 ) is disposed for initiating closing forces into the second nozzle needle ( 19 ),    a control line ( 31 ), which communicates with the first control chamber ( 28 ) and with which the pressure in the first control chamber ( 28 ) can be controlled,    a second control face ( 30 ) in the first control chamber ( 28 ), the second control face ( 30 ), being embodied at or drive-coupled with the first nozzle needle ( 7 ) for initiating closing forces into the first nozzle needle ( 7 );    first coupling path ( 39 ) connecting the first control chamber ( 28 ) directly or indirectly for communication with a pressure source ( 37 ); and    a second coupling path ( 43 ), connecting the first control chamber ( 28 ) for communication with the pressure source ( 37 );    the second coupling path ( 43 ) being controlled as a function of the stroke of the first nozzle needle ( 7 ), in such a way that the second coupling path ( 43 ), beginning at the closing position of the first nozzle needle ( 7 ), is open up to a predetermined prestroke ( 48 ), and is blocked beyond a stroke extending beyond the prestroke ( 48 ).    
   
   
       2 . The injection nozzle in accordance with  claim 1 , further comprising 
 a second control chamber ( 35 ), in which a third control face ( 38 ), embodied at or drive-coupled with the first nozzle needle ( 7 ), is disposed for initiating closing forces into the first nozzle needle ( 7 ); and    an inlet line ( 36 ) connecting the second control chamber ( 35 ) to the pressure source ( 37 );    the second coupling path ( 43 ) connecting the first control chamber ( 28 ) for communication with the second control chamber ( 35 ), so that the first control chamber ( 28 ) communicates with the pressure source ( 37 ) through the second control chamber ( 35 ).    
   
   
       3 . The injection nozzle in accordance with  claim 2 , wherein the second coupling path ( 43 ) has at least one longitudinal groove ( 44 ), which is open toward the first control chamber ( 28 ) and is embodied in a cylindrical portion ( 41 ) of the first nozzle needle ( 7 ) or in a coupling sleeve ( 14 ) drive-coupled to the first nozzle needle ( 7 ), and which when the first nozzle needle ( 7 ) is closed protrudes into the second control chamber ( 35 ); and wherein an end ( 46 ), remote from the first control chamber ( 28 ), of the longitudinal groove ( 44 ) and a wall portion ( 47 ), axially defined by the second control chamber ( 35 ), cooperate as control edges for opening and blocking the second coupling path ( 43 ).  
   
   
       4 . The injection nozzle in accordance with  claim 1 , wherein the first coupling path ( 39 ) is throttled more severely than the second coupling path ( 43 ).  
   
   
       5 . The injection nozzle in accordance with  claim 2 , wherein the first coupling path ( 39 ) is throttled more severely than the second coupling path ( 43 ).  
   
   
       6 . The injection nozzle in accordance with  claim 3 , wherein the first coupling path ( 39 ) is throttled more severely than the second coupling path ( 43 ).  
   
   
       7 . The injection nozzle in accordance with  claim 1 , wherein the first coupling path ( 39 ) is throttled more severely than the inlet line ( 36 ).  
   
   
       8 . The injection nozzle in accordance with  claim 3 , wherein the first coupling path ( 39 ) is throttled more severely than the inlet line ( 36 ).  
   
   
       9 . The injection nozzle in accordance with  claim 1 , wherein the control line comprises an outlet line ( 31 ) connecting the first control chamber ( 28 ) to a pressure sink ( 34 ); and 
 means switching the connection can be switched at least between an open state and a blocked state.    
   
   
       10 . The injection nozzle in accordance with  claim 3 , wherein the control line comprises an outlet line ( 31 ) connecting the first control chamber ( 28 ) to a pressure sink ( 34 ); and 
 means switching the connection can be switched at least between an open state and a blocked state.    
   
   
       11 . The injection nozzle in accordance with  claim 4 , wherein the control line comprises an outlet line ( 31 ) connecting the first control chamber ( 28 ) to a pressure sink ( 34 ); and 
 means switching the connection can be switched at least between an open state and a blocked state.    
   
   
       12 . The injection nozzle in accordance with  claim 7 , wherein the control line comprises an outlet line ( 31 ) connecting the first control chamber ( 28 ) to a pressure sink ( 34 ); and 
 means switching the connection can be switched at least between an open state and a blocked state.    
   
   
       13 . The injection nozzle in accordance with  claim 1 , wherein the outlet line ( 31 ), the inlet line ( 36 ), the coupling paths ( 39 ,  43 ), the nozzle needles ( 7 ,  19 ), and the control faces ( 29 ,  30 ,  38 ) are designed such that in the open state of the outlet line ( 31 ), a pressure is established in the first control chamber ( 28 ) that, when the second coupling path ( 43 ) is open, is so great that a resultant force, engaging the second nozzle needle ( 19 ), acts in the closing direction ( 17 ) of the second nozzle needle ( 19 ), and when the second coupling path ( 43 ) is blocked is so great that the resultant force engaging the second nozzle needle ( 19 ) acts in the opening direction ( 18 ) of the second nozzle needle ( 19 ).  
   
   
       14 . The injection nozzle in accordance with  claim 9 , wherein the outlet line ( 31 ), the inlet line ( 36 ), the coupling paths ( 39 ,  43 ), the nozzle needles ( 7 ,  19 ), and the control faces ( 29 ,  30 ,  38 ) are designed such that in the open state of the outlet line ( 31 ), a pressure is established in the first control chamber ( 28 ) that, when the second coupling path ( 43 ) is open, is so great that a resultant force, engaging the second nozzle needle ( 19 ), acts in the closing direction ( 17 ) of the second nozzle needle ( 19 ), and when the second coupling path ( 43 ) is blocked is so great that the resultant force engaging the second nozzle needle ( 19 ) acts in the opening direction ( 18 ) of the second nozzle needle ( 19 ).  
   
   
       15 . The injection nozzle in accordance with  claim 1 , wherein the first coupling path ( 39 ) connects the first control chamber ( 28 ) for communication with the second control chamber ( 35 ), so that the first control chamber ( 28 ) communicates with the pressure source ( 37 ) through the second control chamber ( 35 ).  
   
   
       16 . The injection nozzle in accordance with  claim 4 , wherein the first coupling path ( 39 ) connects the first control chamber ( 28 ) for communication with the second control chamber ( 35 ), so that the first control chamber ( 28 ) communicates with the pressure source ( 37 ) through the second control chamber ( 35 ).  
   
   
       17 . The injection nozzle in accordance with  claim 12 , wherein the first coupling path ( 39 ) connects the first control chamber ( 28 ) for communication with the second control chamber ( 35 ), so that the first control chamber ( 28 ) communicates with the pressure source ( 37 ) through the second control chamber ( 35 ).  
   
   
       18 . The injection nozzle in accordance with  claim 1 , further comprising to at least one transverse bore ( 40 ), which radially penetrates a cylindrical portion ( 41 ) in the first nozzle needle ( 7 ) or in a coupling sleeve ( 14 ) drive-coupled to the first nozzle needle ( 7 ) defining at least a portion of the first coupling path ( 43 ), and an annular chamber ( 42 ) disposed radially between the second nozzle needle ( 19 ), or a coupling rod ( 26 ) drive-coupled to the second nozzle needle ( 19 ), and the first nozzle needle ( 7 ), or a coupling sleeve ( 14 ) drive-coupled to the first nozzle needle ( 7 ), the annular chamber ( 42 ) being open toward the first control chamber ( 28 ) and communicating with the second control chamber ( 35 ) via the at least one transverse bore ( 40 ).  
   
   
       19 . The injection nozzle in accordance with  claim 1 , wherein the first coupling path ( 39 ) is disposed such that it is open in all the stroke positions of the nozzle needles ( 7 ,  19 ).  
   
   
       20 . The injection nozzle in accordance with  claim 1 , wherein the inlet line ( 36 ) is disposed such that it is open in all the stroke positions of the nozzle needles ( 7 ,  19 ).