Compression release valvetrain design
Systems, apparatuses and methods are disclosed that include an internal combustion engine including a plurality of cylinders operable by a valve actuation mechanism including a lifting mechanism having a compression brake valve profile configured to selectively lift the exhaust valves on a downstroke of the cylinders in response to a cranking condition of the internal combustion engine, wherein the compression braking valve profile is phased to the upstroke of the pistons.
1. A system, comprising:
an internal combustion engine including a plurality of cylinders connected to an intake system and to an exhaust system, each of the cylinders including at least one intake valve, at least one exhaust valve and a piston; and
a valve actuation mechanism connected to each of the plurality of cylinders, the valve actuation mechanism including a valve train assembly to operate the at least one intake valve and at least one exhaust valve in one of a normal valve profile and a compression brake valve profile,
wherein the compression brake valve profile is configured to selectively lift the exhaust valve in response to cranking of the internal combustion engine,
wherein the valve train assembly includes a phaser that phases the compression brake valve profile to an upstroke of the piston during the cranking until the internal combustion engine achieves a speed threshold for combustion, and
wherein prior to the cranking of the internal combustion engine the valve actuation mechanism is locked on the compression brake valve profile with the phaser and switched from the compression brake valve profile to the normal valve profile when the internal combustion engine achieves the speed threshold for combustion.
2. The system of claim 1 , further comprising:
a motor generator structurally configured to maintain a specified cranking speed of the engine based on a gas compression load of the cylinders.
3. The system of claim 1 , wherein, prior to the cranking of the internal combustion engine, the valve actuation mechanism is locked on the compression brake valve profile with the phaser.
4. A system, comprising:
an internal combustion engine including a plurality of cylinders connected to an intake system and to an exhaust system, each of the cylinders including at least one intake valve, at least one exhaust valve and a piston; and
a valve actuation mechanism connected to each of the plurality of cylinders, the valve actuation mechanism including a cylinder deactivation mechanism configured to deactivate the intake valves and the exhaust valves in response to a cranking of the internal combustion engine,
wherein the cylinder deactivation mechanism closes the intake valves and the exhaust valves during the cranking so there is no airflow through the internal combustion engine until the internal combustion engine obtains a threshold speed.
5. The system of claim 4 , further comprising:
a motor generator structurally configured to maintain a specified cranking speed of the engine based on a gas compression load of the cylinders.
6. A method, comprising:
cranking an internal combustion engine, the internal combustion engine including a plurality of cylinders connected to an intake system and to an exhaust system, each of the cylinders including at least one intake valve, at least one exhaust valve, and a piston, the internal combustion engine further including a valve actuation mechanism connected to each of the plurality of cylinders, the valve actuation mechanism including a valve train assembly to operate the at least one intake valve and the at least one exhaust valve in one of a normal valve profile and a compression brake valve profile;
operating the at least one intake valve, the at least one exhaust valve, and the piston based on one of the normal valve profile and the compression brake valve profile; and
in response to the cranking of the internal combustion engine, selectively lifting the at least one exhaust valve based on the compression brake valve profile, wherein the valve train assembly includes a phaser that phases the compression brake valve profile to an upstroke position of the piston during the cranking, and prior to the cranking the valve actuation mechanism is locked on the compression brake valve profile with the phaser until a desired cranking speed of the internal combustion engine is achieved.
7. The method of claim 6 , further comprising:
selectively lifting the at least one intake valve and the at least one exhaust valve based on the normal valve profile in response to achieving the desired cranking speed of the internal combustion engine.
8. The method of claim 6 , further comprising:
initiating a combustion event in response to achieving the desired cranking speed of the internal combustion engine.