Device for controlling charge exchange valves

Abstract

A device is proposed for controlling gas-exchange valves, at least one of which is assigned as intake valve ( 11 ) and at least one of which as discharge valve ( 12 ) to a combustion chamber of an internal combustion engine. The internal combustion engine includes electrohydraulic valve actuators ( 18 ) assigned in each case to a gas-exchange valve for its actuation, and a pressure-supply reservoir ( 26 ) having a high-pressure pump and a pressure-storage unit, which supplies the valve-actuators ( 18 ) with a fluid at high pressure. To reduce the energy consumed by the control device, the pressure-storage unit has two separate high-pressure reservoirs ( 31, 32 ), one of which is connected to the valve actuator ( 18 ) for the at least one intake valve ( 11 ) and the other to the valve actuator ( 18 ) for the at least one discharge valve ( 12 ). With the aid of a switching member ( 30 ), the high-pressure pump ( 27 ) is alternatively able to be connected to one or the other high-pressure reservoir ( 31, 32 ) and to a return line ( 37 ) leading to a fluid reservoir ( 29 ).

What is claimed is:  
     
         1 . A device for controlling gas-exchange valves, at least one of which is assigned as an inlet valve ( 11 ) and at least one as a discharge valve ( 12 ) to a combustion chamber of the internal combustion engine, each having an electrohydraulic valve actuator ( 18 ) assigned to a gas-exchange valve ( 11 ,  12 ) for its actuation, and having a pressure-supply device ( 26 ) supplying the valve actuators ( 18 ) with a fluid at high pressure, the pressure-supply device ( 26 ) having a high-pressure pump and a pressure-storage unit, wherein the pressure accumulator unit has two separate high-pressure accumulators ( 31 ,  32 ), one of which is connected to the valve actuator ( 18 ) for the at least one intake valve ( 11 ) and the other to the valve actuator ( 18 ) for the at least one discharge valve ( 12 ), and the high-pressure pump is optionally connectable by way of a switching member ( 30 ) to the one or to the other high-pressure accumulator ( 31 ,  32 ) and to a return line ( 37 ) leading to a fluid reservoir ( 29 ).  
     
     
         2 . The device as recited in  claim 1 , wherein the high-pressure pump is configured as constant displacement pump ( 27 ) whose pump outlet is connected to the inlet of the switching member ( 30 ).  
     
     
         3 . The device as recited in  claim 1  or  2 , wherein the switching member ( 30 ) is configured as a 4/3 directional solenoid control valve ( 41 ) having one valve inlet ( 411 ) and three valve outlets ( 412 ,  413 ,  414 ) having spring setting, whose valve inlet ( 411 ) is connected to the pump outlet and one of whose three valve outlets ( 412 ,  413 ,  414 ) is connected to the one and the other to the other high-pressure accumulator ( 31 ,  32 ) and the third is connected to the return line ( 37 ).  
     
     
         4 . The device as recited in  claim 3 , wherein the 4/3 directional solenoid control valve ( 41 ) is controlled by an electronic control device ( 13 ).  
     
     
         5 . The device as recited in one of claims  1  through  4 , wherein the two high-pressure reservoirs ( 31 ,  32 ) are set to different pressure levels.  
     
     
         6 . The device as recited in  claim 5 , wherein the high-pressure reservoirs ( 31 ,  32 ) are in each case connected via a pressure relief valve ( 35 ,  36 ) to the return line ( 37 ).  
     
     
         7 . The device as recited in one of claims  1  through  6 , wherein in a plurality of gas-exchange valves ( 11 ,  12 ) the valve actuators ( 18 ) of all intake valves ( 11 ) are connected to one, and the valve actuators ( 18 ) of all outlet valves ( 12 ) are connected to the other high-pressure reservoir ( 31 ,  32 ).  
     
     
         8 . The device as recited in one of claims  2  through  7 , wherein a presupply pump ( 28 ) delivering from the fluid reservoir ( 29 ) is arranged upstream from the constant displacement pump ( 27 ).  
     
     
         9 . The device as recited in one of claims  2  through  7 , wherein the constant displacement pump ( 27 ) is implemented as self-priming pump whose pump intake is directly connected to the fluid reservoir ( 29 ).  
     
     
         10 . The device as recited in one of claims  1  through  9 , wherein each electrohydraulic valve actuator ( 18 ) has a double-acting hydraulic working cylinder ( 19 ) for valve actuation and electric control valves ( 20 ,  21 ) controlling the operating pressure in the working cylinder ( 19 ).