Control system for pressure wave supercharger to optimize emissions and performance of an internal combustion engine

• US 5,839,416 A
• Filed: 11/12/1996
• Issued: 11/24/1998
• Est. Priority Date: 11/12/1996
• Status: Expired due to Fees

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Kruiswyk, Richard W., Liang, Cho Y.
• Primary Examiner(s): KOCZO JR, MICHAEL
• Application Number:
  US08/748,141
• Time in Patent Office: 742 Days
• Field of Search: 60/602, 123/559.2
• US Class Current: 123/559.2
• CPC Class Codes: F02B 33/42 with driven apparatus for immediate conversion of combustion gas pressure into pressure of fresh charge, e.g. with cell-type pressure exchangers

Abstract

A control system for an internal combustion engine and an associated pressure wave supercharger, which optimizes exhaust emissions and engine performance by automatically switching the mode of control between a cold start and white smoke mode, an altitude dependent mode, a low emissions mode, a fuel economy mode, and a particulate trap regeneration mode as the operating conditions of the engine change.

Claims

1. A control system for an internal combustion engine having a liquid coolant, an intake manifold for supplying combustion air to the engine, an exhaust manifold for the high pressure exhaust gases and a fuel injection system which is adapted to vary the timing of the fuel injection and a pressure wave supercharger having a circular array of elongated chambers disposed to rotate about a central axis, a variable speed drive to rotate the circular array of elongated chambers, a low pressure combustion air duct and a high pressure combustion air duct each disposed in fluid communication with the same end of a plurality of different elongated chambers, a high pressure exhaust duct and a low pressure exhaust duct each disposed in fluid communication with the other end of a plurality of different elongated chambers, disposed between the high pressure exhaust duct and the low pressure exhaust ducts and in fluid communication with the other end of a plurality of elongated chambers is a gas pocket, the gas pocket is also in fluid communication with the high pressure exhaust duct through a flow control valve, the high pressure exhaust duct is disposed in fluid communication with the exhaust manifold via an exhaust conduit, which has a restrictor valve disposed therein, and the low pressure exhaust duct is disposed in fluid communication with the atmosphere, the high pressure combustion air duct is disposed in fluid communication with the intake manifold and the low pressure combustion air duct is disposed in fluid communication with the atmosphere and has a restrictor valve disposed therein;

the control system being characterized in that, the control system automatically switches from one mode of operation to another in response to varying operating conditions and emissions requirements utilizing a plurality of maps based on fixed data points obtained from empirical data specific to the engine and pressure wave supercharger and the particular mode of engine operation to optimize engine performance and control emissions.

2. A control system for an internal combustion engine as set forth in claim 1 characterized in that the modes of operation of the control system comprise a cold start and white smoke mode, an altitude dependent mode, and a low emissions mode.

3. A control system for an internal combustion engine as set forth in claim 2 further comprising a particulate trap disposed in the exhaust conduit and characterized in that the modes of operation of the control system further comprises a fuel economy mode and a particulate trap regeneration mode.

4. A control system for an internal combustion engine as set forth in claim 2 characterized in that when the liquid coolant temperature is below a predetermined value, the control system operates on one set of maps based on fixed data points obtained from empirical data specific to the engine and pressure wave supercharger to heat the engine rapidly and minimize white smoke, when the atmospheric pressure is below a predetermined level, the control system switches to operate on another set of maps based on fixed data points obtained from empirical data specific to the engine and pressure wave supercharger to increase the pressure of the high pressure combustion air and minimize the exhaust temperature, and when the rate of change of the fuel rate is above a predetermined level, the control system switches to operate on another set of maps based on fixed data points obtained from empirical data specific to the engine and pressure wave supercharger to optimize hydrocarbon and NOx emissions, thereby optimizing the engines performance and controlling emissions as the engine operates in different modes.

5. A control system for an internal combustion engine as set forth in claim 3 characterized in that the rate of change of the fuel rate is below a predetermined level, the control system switches to another set of maps based on fixed data points obtained from empirical data specific to the engine and pressure wave supercharger to provide the lowest fuel consumption and when the pressure in the exhaust manifold reaches a predetermined level the control system switches to another set of maps based on fixed data points obtained from empirical data specific to the engine and pressure wave supercharger to increase the exhaust temperature to burn off accumulated soot and regenerate the particulate trap.

6. A control system for an internal combustion engine as set forth in claim 2 further characterized in that when the liquid coolant is below a predetermined temperature the control system opens the combustion air restrictor valve to its fully open position, the variable speed drive, the gas pocket valve and the exhaust restrictor valve are adjusted to provide optimum exhaust gas recirculation to aid starting, engine warm-up and white smoke cleanup in accordance with the empirical data points specific to this mode of engine operation.

7. A control system for an internal combustion engine as set forth in claim 6 further characterized in that when the atmospheric pressure is below a predetermined level the fuel injection timing is advanced to minimize exhaust temperature with lower atmospheric pressure, the variable speed drive and gas pocket valve are adjusted to increase the pressure of the high pressure combustion air in accordance with the empirical data points specific to this mode of engine operation.

8. A control system for an internal combustion engine as set forth in claim 7 further characterized in that when the rate of change of the fuel rate is above a predetermined level, the variable speed drive and the gas pocket valve are adjusted to optimize the pressure of the high pressure combustion air for low particulate emission, the fuel injection timing device is adjusted for low NOx emissions and the intake restrictor valve is adjusted to control exhaust gas recirculation to provide further NOx reduction, if necessary, in accordance with the empirical data points specific to this mode of engine operation.

9. A control system for an internal combustion engine as set forth in claim 3 further characterized in that when the rate of change of the fuel rate is below a predetermined level, the intake and exhaust valves are advanced to wide open to minimize pressure drops and reduce pumping work of the engine and the gas pocket valve and variable speed drive are adjusted to optimize the overall efficiency of pressure wave supercharger and the fuel injection timing device is adjusted to provide the lowest fuel consumption, in accordance with the empirical data points specific to this mode of engine operation.

10. A control system for an internal combustion engine as set forth in claim 9 further comprising a particulate trap disposed in the exhaust conduit and characterized in that when the exhaust manifold pressure reaches a predetermined level the fuel injection timing is retarded to increase the exhaust temperature to regenerate the particulate trap by burning off accumulated soot, if the exhaust manifold has not dropped below the predetermined level, the variable speed drive, the gas pocket valve and the exhaust restrictor valve are adjusted to increase exhaust gas recirculation to further increase the exhaust temperature to regenerate the particulate trap by burning off the remaining soot.