Method for operating an electrohydraulic valve control system of an internal combustion engine, computer program, and control, and regulating unit for operating an internal combustion engine

Abstract

An electrohydraulic valve control ( 10 ) of an internal combustion engine includes at least one actuator ( 24 ) that acts on a gas exchange valve ( 38 ). This actuator ( 24 ) in turn has at least one working chamber ( 30 ), which in order to switch the actuator ( 24 ) from a first position into a second position, is connected to a high-pressure hydraulic accumulator ( 16 ) and shut off from a low-pressure return ( 56 ). In order to switch the actuator ( 24 ) from the second position back into the first position, the working chamber ( 30 ) is connected to the low-pressure return ( 56 ) and shut off from the high-pressure hydraulic accumulator ( 16 ). The pressure in the high-pressure hydraulic accumulator ( 16 ) is kept constant or reduced in a simple manner by virtue of the working chamber ( 30 ) being connected to the high-pressure hydraulic accumulator ( 16 ) and the low-pressure return ( 56 ) at the same time.

1 . A method for operating an electrohydraulic valve control ( 10 ) of an internal combustion engine, with at least one actuator ( 24 ) that acts on a gas exchange valve ( 38 ) and has at least one working chamber ( 30 ), which in order to switch the actuator ( 24 ) from a first position into a second position, is connected to a high-pressure hydraulic accumulator ( 16 ) and shut off from a low-pressure return ( 56 ), and in order to switch the actuator ( 24 ) from the second position back into the first position, is connected to the low-pressure return ( 56 ) and shut off from the high-pressure hydraulic accumulator ( 16 ), characterized in that the pressure in the high-pressure hydraulic accumulator ( 16 ) is kept constant or reduced by virtue of the working chamber ( 30 ) being connected to the high-pressure hydraulic accumulator ( 16 ) and the low-pressure return ( 56 ) at the same time.  
     
     
         2 . The method according to  claim 1 , characterized in that in order to stabilize or reduce the pressure in the high-pressure hydraulic accumulator ( 16 ), the working chamber ( 30 ) of an actuator ( 24 ) is connected to the high-pressure hydraulic accumulator ( 16 ) and the low-pressure return ( 56 ) simultaneously and its associated gas exchange valve ( 38 ) is closed at the time.  
     
     
         3 . The method according to  claim 2 , characterized in that in order to stabilize or reduce the pressure in the high-pressure hydraulic accumulator ( 16 ), the working chamber ( 30 ) of an actuator ( 24 ) is connected to the high-pressure hydraulic accumulator ( 16 ) and the low-pressure return ( 56 ) simultaneously and its associated gas exchange valve ( 38 ) cannot open at the time due to a high pressure in the combustion chamber ( 44 ).  
     
     
         4 . The method according to one of the preceding claims, characterized in that the working chamber ( 30 ) of an actuator ( 24 ), which is to be moved from the first position into the second position, is connected to the high-pressure hydraulic accumulator ( 16 ) just before being shut off from the low-pressure return ( 56 ), and/or the working chamber ( 30 ) of an actuator ( 24 ), which is to be moved from the second position into the first position, is connected to the low-pressure return ( 56 ) just before being shut off from the high-pressure hydraulic accumulator ( 16 ).  
     
     
         5 . The method according to one of the preceding claims, characterized in that the working chamber ( 30 ) of an actuator ( 24 ) is temporarily connected to the high-pressure hydraulic accumulator ( 16 ) and the low-pressure return ( 56 ) simultaneously when the internal combustion engine is operated at a low speed.  
     
     
         6 . The method according to one of the preceding claims, characterized in that there is also a control or regulation of the delivery quantity by means of the hydraulic pump ( 14 ).  
     
     
         7 . The method according to one of the preceding claims, characterized in that the actuator ( 24 ) has two working chambers ( 30 ,  32 ) that are separated from each other by pressure surfaces ( 34 ,  36 ) on a piston ( 26 ), which are of different sizes and work in opposition to each other, and the one working chamber ( 32 ) is continuously acted on by high pressure while the other working chamber ( 30 ) can be connected to the high-pressure hydraulic accumulator ( 16 ) and the low-pressure return ( 56 ).  
     
     
         8 . The method according to one of the preceding claims, characterized in that the hydraulic fluid flows out of the working chamber ( 30 ) into a low-pressure hydraulic accumulator ( 52 ).  
     
     
         9 . A computer program, characterized in that it is suitable for executing the method according to one of the preceding claims when it is run on a computer.  
     
     
         10 . The computer program according to  claim 11 , characterized in that it is stored in a memory, in particular a flash memory or a ferrite RAM.  
     
     
         11 . A control and regulating unit ( 78 ) for operating an internal combustion engine, which is connected to a first control valve ( 22 ) and a second control valve ( 50 ) of an electrohydraulic valve control ( 10 ), which can be used to connect a working chamber ( 30 ) of an actuator ( 24 ) of a gas exchange valve ( 38 ) to a high-pressure hydraulic accumulator ( 16 ) and a low-pressure return ( 56 ), characterized in that it is suitable for executing the method according to one of  claims 1  to  8 .  
     
     
         12 . The control and regulating unit ( 78 ) according to  claim 12 , characterized in that it is provided with a computer program according to one of claims  9  or  10 .