Systems and Methods to Control Torsional Vibration in an Internal Combustion Engine with Cylinder Deactivation
The present disclosure utilizes deactivated cylinders in a variable displacement engine to control the torsional vibration of a crankshaft. In a deactivated mode, deactivated cylinders are compressed and expanded by a reciprocating piston, but they are doing no net work and still causing an oscillating torque on the crankshaft. The present disclosure utilizes this oscillating torque to counter torque from the active cylinders. This is done through controlling the gas pressure in the deactivated cylinders by using intake and exhaust values to equalize the pressure between the cylinder and ports. The optimum gas pressure in deactivated cylinders to minimize total torque fluctuations is approximately one-half that of the active cylinders. A closed control loop adjusts gas pressure in the deactivated cylinders to cancel out torque from the active cylinders.
1 . A method to control torsional vibrations due to cylinder deactivation, comprising:
measuring gas pressure in an active and a deactivated cylinder;
determining a target pressure for the deactivated cylinder responsive to the measured gas pressure in the active cylinder; and
adjusting a phase on a pressure control valve of the deactivated cylinder responsive to a difference between the measured gas pressure in the deactivated cylinder and the determined target pressure for the deactivated cylinder.
2 . The method to control torsional vibrations of claim 1 , wherein the measuring step is performed by a cylinder pressure sensor.
3 . The method to control torsional vibrations of claim 1 , wherein the target pressure comprises a value that is approximately one-half of the measured gas pressure in the active cylinder.
4 . The method to control torsional vibrations of claim 1 , wherein the target pressure comprises a value that is determined through one of measurement and simulation.
5 . The method to control torsional vibrations of claim 1 , wherein the adjusting step comprises:
if the measured gas pressure in the deactivated, cylinder is higher than the target pressure, moving the pressure control, valve phase away from bottom dead center; and
if the measured gas pressure in the deactivate cylinder is lower than the target pressure, moving the pressure, control valve phase closer to bottom dead, center.
6 . The method to control torsional vibrations of claim 1 , wherein pressure control valves comprise one of an intake valve, an exhaust valve, and combinations thereof.
7 . The method to control torsional vibrations of claim 1 , further comprising:
opening the pressure control valve when a piston is at bottom dead center;
wherein the adjusting phase step is operable to adjust the opening of the pressure control valve in order to equalize gas pressure in the deactivated cylinder.
8 . The method to control torsional vibrations of claim 1 , wherein the target pressure provides torque oscillations from the deactivated cylinder that is out of phase with the torque oscillations from the active cylinder; and
wherein the torque oscillations from the deactivated cylinder and the torque oscillations from the active cylinder cancel each other out thereby reducing torsional vibrations.
9 . The method to control torsional vibrations of claim 1 , wherein the adjusting step and determining steps are performed by an electronic control unit;
wherein the measuring step is performed by a cylinder pressure sensor;
wherein the cylinder pressure sensor communicates measured gas pressure to the electronic control unit; and
wherein the electronic control unit operates the pressure control valve to achieve the target pressure in the deactivated cylinder.
10 . A torsional vibration control system for engine configured with cylinder deactivation, comprising:
a plurality of cylinders each comprising a cylinder pressure sensor and a pressure control valve, wherein the cylinder pressure sensor is configured to measure gas pressure in the cylinder; and
an electronic control unit in communication with each of the cylinder pressure sensors in the plurality of cylinders, wherein the electronic control unit is configured to:
receive gas pressure measurements for each of the plurality of cylinders;
determine a maximum gas pressure for each active cylinder of the plurality of cylinders;
compute an average of the maximum gas pressures for each active cylinder;
determine an optimal pressure for each deactivated cylinder of the plurality of cylinders responsive to the computed gas pressures; and
manage the pressure control valve in each of the deactivated cylinders to achieve the optimal pressure.
11 . The torsional vibration control system of claim 10 , wherein the pressure control valve comprises one of an intake valve, an exhaust valve, and combinations thereof.
12 . The torsional vibration control system of claim 10 , wherein the optimal pressure comprises one-half of the average of the maximum gas pressures for each active cylinder.
13 . The torsional vibration control system of claim 10 , wherein the optimal pressure comprises a value that is determined through one of measurement and simulation.
14 . The torsional vibration control system of claim 10 , wherein the pressure control valve on each of the deactivated cylinders is configured, to open when a piston is at bottom dead center.
15 . The torsional vibration control system of claim 13 , wherein the opening of the pressure control valve is operable to equalize gas pressure in the deactivated cylinder with a port, wherein the port comprises one of an intake port and an exhaust port.
16 . The torsional vibration control system of claim 10 , wherein the optimal pressure provides torque oscillations from the deactivated cylinder that is out of phase with the torque oscillations from the active cylinder; and
wherein the torque oscillations from each of the deactivated cylinders and the torque oscillations from each of the active cylinders cancels each other out thereby reducing torsional vibrations.
17 . A closed control loop method to control torsional vibrations in a V8 engine with variable displacement due to cylinder deactivation, comprising:
measuring gas pressure in a plurality of active and deactivated cylinders;
determining the maximum gas pressure value for an engine cycle for each of the plurality of active cylinders;
averaging the maximum gas pressure value for each of the plurality of active cylinders;
dividing the average by one-half to obtain a target pressure for each of the plurality of deactivated cylinders;
comparing the target pressure to the measured gas pressure for each of the deactivated cylinders;
adjusting the phase of a pressure control value for each of the plurality of deactivated cylinders responsive to the comparing step; and
opening the pressure control valve for each of the plurality of deactivated cylinders when a piston is at bottom dead center.
18 . The closed control loop method to control torsional vibrations of claim 17 , wherein the closed control loop is repeated while an engine is in cylinder deactivation mode.