Engine pre turbine pressure monitoring system
A pressure monitor is arranged to calculate a pre-turbine pressure. The monitor is programmed to derive a normalized turbine speed, normalized for a pre turbine temperature, and a heat capacity ratio of exhaust gas before the turbine as first inputs; determine a turbine power normalizing factor as a second input; determine an actual turbocompressor power value as a third input; derive, for said first inputs, a linear relation between a turbine expansion ratio and a turbine power value normalized by the second input; and equate the turbine power value to the actual turbocompressor power; thereby deriving the pre turbine pressure from said linear relation, as an output.
1. An internal combustion engine comprising:
an inlet manifold providing compressed inlet air into a plurality of cylinders;
an exhaust manifold for exhausting combusted gases from the plurality of cylinders;
a turbine provided in an exhaust channel coupled to the exhaust manifold;
a turbocompressor provided in an inlet channel coupled to the inlet manifold;
a pressure monitor comprising a computing device arranged to calculate a pre turbine pressure (p 3 ), wherein the computing device is programmed to:
receive data from one or more of the inlet manifold, the exhaust manifold, the turbine, or the turbocompressor;
derive, based on the data, a normalized turbine speed, normalized for a pre turbine temperature, and a heat capacity ratio of exhaust gas before the turbine as first inputs;
determine a turbine power normalizing factor as a second input;
determine, based on the data, an actual turbocompressor power value as a third input;
derive, for said first inputs, a linear relation between a turbine expansion ratio and a turbine power value normalized by the second input;
generate an output by equating the turbine power value to the actual turbocompressor power, thereby deriving the pre turbine pressure from said linear relation; and
modify, based on the output, an operating parameter of the internal combustion engine.
2. The internal combustion engine according to claim 1 , wherein the turbine power normalizing factor is a product of post turbine pressure, heat capacity at constant pressure of the exhaust gas and square root of the pre-turbine temperature.
3. The internal combustion engine according to claim 1 , wherein the normalized turbine speed is calculated from a quotient of the turbine speed and a square root of the pre-turbine temperature.
4. The internal combustion engine according to claim 1 , wherein the pre-turbine temperature is measured directly or derived from the turbine power and a post turbine temperature.
5. The internal combustion engine according to claim 1 , wherein the turbine is a variable geometry turbine having an adjustable turbine nozzle position, wherein said linear relation is further derived for each turbine nozzle position.
6. The internal combustion engine according to claim 1 , wherein the turbocompressor power is derived from a product of compressor mass flow, heat capacity at constant pressure of intake air, pre-compressor temperature, and a power factor, based on a compressor mass flow normalized for pre-compressor pressure and temperature, and a turbo speed normalized for pre-compressor temperature.
7. A method for monitoring a pre turbine pressure of in internal combustion engine comprising a turbine provided in an exhaust channel coupled to an exhaust manifold and a turbocompressor provided in an inlet channel coupled to an inlet manifold of the internal combustion engine, the method comprising:
receiving data from one or more of the inlet manifold, the exhaust manifold, the turbine, or the turbocompressor;
deriving, by a computing device and based on the data, a turbine speed, normalized for a pre turbine temperature, and a heat capacity ratio of exhaust gas before the turbine as first inputs;
determining, by the computing device and based on the data, a turbine power normalizing factor as a second input;
determining, by the computing device and based on the data, an actual turbocompressor power value as a third input;
deriving, for said first inputs, a linear relation between a turbine expansion ratio and a turbine power value normalized by the second input;
generating an output by equating the turbine power value to the actual turbocompressor power; thereby deriving the pre turbine pressure from said linear relation, as an output; and
modifying, based on the output, an operating parameter of the internal combustion engine.
8. The method of claim 7 , wherein the turbine power normalizing factor is a product of post turbine pressure, heat capacity at constant pressure of the exhaust gas and square root of the pre-turbine temperature.
9. The method of claim 7 , wherein the normalized turbine speed is calculated from a quotient of the turbine speed and a square root of the pre-turbine temperature.
10. The method of claim 7 , wherein the pre-turbine temperature is measured directly or derived from the turbine power and a post turbine temperature.
11. The method of claim 7 , wherein the turbine is a variable geometry turbine having an adjustable turbine nozzle position, wherein said linear relation is further derived for each turbine nozzle position.
12. The method of claim 7 , wherein the turbocompressor power is derived from a product of compressor mass flow, heat capacity at constant pressure of intake air, pre-compressor temperature, and a power factor, based on a compressor mass flow normalized for pre-compressor pressure and temperature, and a turbo speed normalized for pre-compressor temperature.