Single actuator valve sequencing in cylinder deactivation and high-power density (HPD) braking engine environments
A system and associated methods for controlling valve motion in internal combustion engines provide a pulsing component for energizing a solenoid control valve in pulsatile fashion to cause a transient pressure change in a hydraulic network linking the control valve to a common, paired set of intake and exhaust main event deactivation mechanisms, which may be provided in respective valve bridges. The pressure change results in hydraulic deactivation of main event motion of the exhaust valve while avoiding deactivation of main intake event motion and thereby preserving intake main event valve motion, and supporting use of the intake main event motion for additional braking or other operations. The systems and methods are particularly suited for engine environments that employ cylinder deactivation (CDA) combined with high-power density (HPD) engine braking.
1. A system for controlling valve motion to facilitate cylinder deactivation and high-power density (HPD) engine braking in an internal combustion engine having at least one cylinder, the system comprising:
a valve set associated with the at least one cylinder, the valve set comprising at least one intake valve and at least one exhaust valve;
a main event motion system configured to produce main event motion in the at least one intake valve and the at least one exhaust valve;
an engine braking system configured to produce engine braking motion during an engine braking operation by adding motion to at least one of the exhaust valves;
a deactivation system including respective deactivation mechanisms associated with the at least one intake valve and the at least one exhaust valve to selectively deactivate main event motion thereof, the deactivation system further including a control valve and at least one hydraulic link which provides hydraulic communication between the control valve and the deactivation mechanisms;
wherein the deactivation system further includes a pulsing component adapted to energize the control valve to thereby cause a variation in the hydraulic pressure in the at least one hydraulic link during an engine cycle such that, when main exhaust event motion would otherwise occur, the hydraulic pressure in the at least one hydraulic link is sufficient to operate the deactivation mechanism associated with the at least one exhaust valve and main exhaust event motion is deactivated, and such that, when main intake event motion occurs, the hydraulic pressure in the at least one hydraulic link is insufficient to operate the deactivation mechanism associated with the at least one intake valve.
2. The system of claim 1 , wherein the pulsing component is an engine control unit adapted to provide pulsed operation of the control valve.
3. The system of claim 1 , wherein the exhaust deactivation mechanism is characterized by a deactivation avoidance window and wherein the pulsing component is configured to provide a pulse of sufficient duration, or a pulse initiated at an appropriate time, such that the hydraulic pressure on the exhaust deactivation mechanism is maintained at an elevated level throughout the deactivation avoidance window.
4. The system of claim 1 , wherein the main intake event motion of the at least one intake valve facilitates additional braking power in the cylinder.
5. The system of claim 1 , wherein the engine braking system is configured to produce at least two compression release events for each cycle of the internal combustion engine.
6. The system of claim 1 , wherein the main event motion system comprises at least two valve bridges, and wherein the deactivation mechanisms include collapsing mechanisms on the at least two valve bridges.
7. The system of claim 1 , wherein the engine braking system comprises a dedicated brake rocker associated with at least one of the exhaust valves.
8. The system of claim 1 , wherein the engine braking system comprises a brake solenoid valve arranged to control the flow of hydraulic fluid to produce braking motion in one or more valves in the at least one valve set.
9. The system of claim 1 , wherein the deactivation system is adapted to selectively deactivate the intake deactivation mechanism in one or more of the at least one cylinder depending on power needs from the engine.
10. The system of claim 1 wherein the pulsing component is configured to adjust the pulse duration or timing based on the speed of the engine.
11. A method of controlling valve motion to facilitate cylinder deactivation and high-power density (HPD) engine braking in an internal combustion engine having at least one cylinders, the system comprising a valve set associated with each of the at least one cylinder, each of the valve sets comprising at least one intake valve and at least one exhaust valve;
a main event motion system for producing main event motion in each of the valve sets;
an engine braking system for producing engine braking valve motion during an engine braking operation by adding motion to at least one of the exhaust valves; a cylinder deactivation system including deactivators for selectively deactivating main event motion of the intake and exhaust valves in at least one valve set; and a deactivating controller adapted to control the deactivators such that, when main exhaust event motion would otherwise occur, main exhaust event motion is deactivated, and such that, when main intake event motion is not deactivated, the method comprising:
initiating a braking operation in the braking system for at least one of the valve sets;
initiating a cylinder deactivation operation in the cylinder deactivation system, the cylinder deactivation operation tending to deactivate main event motion of at least one intake valve and at least one exhaust valve in the at least one valve set;
pulsing the control valve with the deactivator controller such that main event motion of the at least one exhaust valve is deactivated while main event motion of the at least one intake valve is not deactivated.
12. The method of claim 11 , further comprising providing at least two compression release events for each cycle of the internal combustion engine.
13. The method of claim 12 , wherein the main event motion of the at least one intake valve facilitates a compression release braking event performed in the braking operation.
14. A system for controlling valve motion to facilitate cylinder deactivation and high-power density (HPD) engine braking in an internal combustion engine having at least one cylinder, the system comprising:
a valve set associated with the at least one cylinder, the valve set comprising at least one intake valve and at least one exhaust valve;
a main event motion system configured to produce main event motion in the at least one intake valve and the at least one exhaust valve;
an engine braking system configured to produce engine braking motion during an engine braking operation by adding motion to at least one of the exhaust valves;
a deactivation system including respective deactivators associated with the at least one intake valve and the at least one exhaust valve to selectively deactivate main event motion thereof, the deactivation system further including a deactivator controller and at least one communication link adapted to provide communication between the deactivator controller and the deactivators;
wherein the deactivation system further includes a pulsing component adapted to provide a deactivation signal to the deactivators such that, for a given engine cycle, the deactivator associated with the at least one exhaust valve is deactivated, while the deactivator associated with the at least one intake valve is not deactivated.