Valve train for an internal combustion engine of a motor vehicle, and method for operating such a valve train
A valve train of an internal combustion engine of a motor vehicle includes a rocker arm assigned to a first combustion chamber of the internal combustion engine where via the rocker arm a gas exchange valve assigned to the first combustion chamber is actuatable. An actuating device is assigned to a second combustion chamber of the internal combustion engine where via the actuating device, by supplying the actuating device with a hydraulic fluid, the second combustion chamber is switchable between a firing mode for fired operation and a braking mode for an engine braking operation of the internal combustion engine. A supply of the hydraulic fluid to the actuating device assigned to the second combustion chamber is adjustable by the rocker arm assigned to the first combustion chamber.
1. A valve train ( 10 ) of an internal combustion engine of a motor vehicle, the valve train comprising:
a first rocker arm ( 34 ) assigned to a first combustion chamber ( 12 ) of the internal combustion engine, the first rocker arm ( 34 ) configured to actuate a first gas exchange valve ( 28 ) assigned to the first combustion chamber ( 12 );
a first actuating device ( 42 ) assigned to a second combustion chamber ( 14 ) of the internal combustion engine, the first actuating device ( 42 ) configured to selectively switch the second combustion chamber ( 14 ) between a firing mode and a braking mode via a hydraulic fluid;
wherein a supply of the hydraulic fluid to the first actuating device ( 42 ) is controlled based on a position of the first rocker arm ( 34 );
wherein the first rocker arm ( 34 ) is pivotally disposed on a rocker arm axis, the rocker arm axis including a first conducting element ( 46 ) fluidly connected to a second conducting element ( 48 ) so as to guide the hydraulic fluid to the first actuating device ( 42 );
wherein a fluidic connection between the first and second conducting elements ( 46 , 48 ) is closed when the first rocker arm ( 34 ) is in a first pivot position, and the fluidic connection is opened when the first rocker arm ( 34 ) is in a second pivot position; and
an electric valve device ( 54 ) configured to control a pressure of the hydraulic fluid in the first conducting element ( 46 ) such that the hydraulic fluid is fully depressurized at a time the first rocker arm ( 34 ) is switched to the first pivot position, and the hydraulic fluid is fully pressurized at a time the first rocker arm ( 34 ) is switched to the second pivot position.
2. The valve train ( 10 ) according to claim 1 , wherein the first pivot position comprises a plurality of first pivot positions along a first pivot range of the first rocker arm ( 34 ), wherein the second pivot position comprises a plurality of second pivot positions along a second pivot range of the first rocker arm ( 34 ), and wherein the second pivot range is separate from the first pivot range.
3. The valve train ( 10 ) according to claim 2 , wherein a cam is assigned to the first rocker arm ( 34 ), wherein the cam has a base circle region in which actuation of the first rocker arm ( 34 ) does not occur, and an elevation region which is raised with respect to the base circle region so as to actuate the first rocker arm ( 34 ), and wherein the first pivot range corresponds to the base circle region.
4. The valve train ( 10 ) according to claim 3 , wherein the second pivot range corresponds to at least a part of the elevation region.
5. The valve train ( 10 ) according to claim 1 , wherein the first combustion chamber ( 12 ) follows the second combustion chamber ( 14 ) in an ignition sequence.
6. The valve train ( 10 ) according to claim 1 further comprising:
a second rocker arm ( 36 ) assigned to the second combustion chamber ( 14 ), the second rocker arm ( 36 ) configured to actuate a second gas exchange valve ( 30 ) assigned to the second combustion chamber ( 14 ); and
a second actuating device ( 44 ) assigned to a third combustion chamber ( 16 ) of the internal combustion engine, the second actuating device ( 44 ) configured to selectively switch the third combustion chamber ( 16 ) between a firing mode and a braking mode via the hydraulic fluid;
wherein a supply of the hydraulic fluid to the second actuating device ( 44 ) is controlled based on a position of the second rocker arm ( 36 ).
7. The valve train ( 10 ) according to claim 6 further comprising:
a third rocker arm ( 38 ) assigned to the third combustion chamber ( 16 ), the third rocker arm ( 38 ) configured to actuate a third gas exchange valve ( 32 ) assigned to the third combustion chamber ( 16 ); and
a third actuating device ( 40 ) assigned to the first combustion chamber ( 12 ), the third actuating device ( 40 ) configured to selectively switch the first combustion chamber ( 12 ) between a firing mode and a braking mode via the hydraulic fluid;
wherein a supply of the hydraulic fluid to the third actuating device ( 40 ) is controlled based on a position of the third rocker arm ( 38 ).