Claims:1. An engine system comprising:
an engine comprising:
a first fluid regulation component;
a second fluid regulation component operationally coupled to the first fluid regulation component;
a processing subsystem operationally coupled to the first fluid regulation component and the second fluid regulation component and configured to:
obtain one of an amount of opening of the first fluid regulation component and an amount of opening of the second fluid regulation component;
determine the amount of opening of the first fluid regulation component when the amount of opening of the second fluid regulation component is obtained, wherein the amount of opening of the first fluid regulation component is determined based on a coupling relationship between the first fluid regulation component and the second fluid regulation component and the amount of opening of the second fluid regulation component;
determine the amount of opening of the second fluid regulation component when the amount of opening of the first fluid regulation component is obtained, wherein the amount of opening of the second fluid regulation component is determined based on the coupling relationship between the first fluid regulation component and the second fluid regulation component and the amount of opening of the first fluid regulation component; and
controlling the first fluid regulation component and the second fluid regulation component to execute the amount of opening of the first fluid regulation component and the amount of opening of the second fluid regulation component.

2. The engine system of claim 1, wherein the coupling relationship between the first fluid regulation component and the second fluid regulation component, comprises at least one of at least one of a power law constrained coupling relationship, a sigmoid coupling relationship, a linear coupling relationship, a polynomial coupling relationship, a spline coupling relationship and a quadratic coupling relationship.

3. The engine system of claim 1, wherein the first fluid regulation component comprises a first valve and the second fluid regulation component comprises a second valve, wherein the first fluid regulation component is coupled to a first path extending from an exhaust gas recirculation manifold to an intake manifold of the engine, wherein the second fluid regulation component is coupled to a second path extending from the first path to an exhaust manifold of the engine.

4. The engine system of claim 3, wherein the first fluid regulation component is configured to recirculate a first portion of an exhaust gas generated by the engine, within the engine.

5. The engine system of claim 4, wherein the second fluid regulation component is configured to direct a second portion of the exhaust gas outwards from the engine.

6. The engine system of claim 5, wherein the processing subsystem comprises a first module configured to determine a desired amount of oxygen fraction in the intake manifold based on one or more operational parameters of the engine.

7. The engine system of claim 6, wherein the one or more operational parameters comprises engine horsepower, engine speed, ambient conditions, a maximum cylinder pressure, a speed of a turbocharger, or combinations thereof.

8. The engine system of claim 6, wherein the processing subsystem further comprises a second module coupled to the first module and configured to:
determine a desired amount of the exhaust gas to be recirculated within the engine based on the desired amount of oxygen fraction; and
determine a desired boost pressure in the intake manifold based on one or more of the operational parameters.

9. The engine system of claim 8, wherein the processing subsystem further comprises:
a first dynamic controller module coupled to the second module and configured to receive a current amount of the exhaust gas recirculated within the engine, and determine an exhaust-gas-recirculation error based on the current amount of the exhaust gas recirculated within the engine and the desired amount of the exhaust gas to be recirculated within the engine; and
a second dynamic controller module coupled to the second module and configured to receive a current boost pressure in the intake manifold and determine a boost-pressure-error based on the current boost pressure and the desired boost pressure.

10. The engine system of claim 9, wherein the processing subsystem comprises an exhaust-gas-recirculation coupling module coupled to the first dynamic controller module and the second dynamic controller module and configured to determine the amount of opening of the first fluid regulation component or the amount of opening of the second fluid regulation component.

11. The engine system of claim 9, wherein the processing subsystem is further configured to determine the coupling relationship by generating an objective function such that the exhaust-gas-recirculation error is less than or equal to a first threshold.

12. The engine system of claim 11, wherein the processing subsystem is further configured to generate the objective function such that a pressure differential across the first fluid regulation component or the second fluid regulation component is less than or equal to a second threshold.
13. The engine system of claim 11, wherein the objective function further defines the desired amount of the exhaust gas recirculated within the engine within the engine as a function of the amount of opening of the first fluid regulation component or the amount of opening of the second fluid regulation component.

14. The engine system of claim 13, wherein the objective function further defines the desired amount of the exhaust gas recirculated within the engine as a function of the amount of opening of the first fluid regulation component and the amount of the second fluid regulation component.

15. The engine system of claim 14, wherein the objective function further defines a pressure differential across the first fluid regulation component or across the second fluid regulation component as function of the amount of opening of the first fluid regulation component or the amount of opening of the second fluid regulation component.

16. A method comprising:
obtaining one of an amount of opening of a first fluid regulation component and an amount of opening of a second fluid regulation component of an engine;
determining the amount of opening of the first fluid regulation component when the amount of opening of the second fluid regulation component is obtained, wherein the amount of opening of the first fluid regulation component is determined based on a coupling relationship between the first fluid regulation component and the second fluid regulation component and the amount of opening of the second fluid regulation component;
determining the amount of opening of the second fluid regulation component when the amount of opening of the first fluid regulation component is obtained, wherein the amount of opening of the second fluid regulation component is determined based on the coupling relationship between the first fluid regulation component and the second fluid regulation component and the amount of opening of the first fluid regulation component; and
controlling the first fluid regulation component and the second fluid regulation component to execute the amount of opening of the first fluid regulation component and the amount of opening of the second fluid regulation component.

17. The method of claim 16, wherein the coupling relationship between the first fluid regulation component and the second fluid regulation component comprises at least one of at least one of a power law constrained coupling relationship, a sigmoid coupling relationship, a linear coupling relationship, a polynomial coupling relationship, a spline coupling relationship and a quadratic coupling relationship.

18. The method of claim 16, further comprising determining the coupling relationship by generating an objective function such that an exhaust-gas-recirculation error is less than or equal to a first threshold.

19. The method of claim 18, further comprising generating the objective function such that a pressure differential across the first fluid regulation component or the second fluid regulation component is less than or equal to a second threshold.

20. The method of claim 18, further comprising defining the objective function that defines the amount of opening of the first fluid regulation component or the amount of opening of the second fluid regulation component as a function of a desired amount of exhaust gas to recirculated within the engine.
, Description:BACKGROUND
[0001] Embodiments of the present invention relate generally to engine systems, and more particularly to a system and method for controlling fluid regulation components in an engine system.
[0002] A turbocharger of an engine system typically includes a compressor that is rotationally coupled to a turbine via a shaft. The turbine includes a wheel (referred to as ‘turbine wheel’) that is rotated by the flow of the exhaust gas. The turbine wheel is rotatably coupled to a wheel (referred to as ‘compressor wheel’) of a compressor. The compressor is disposed in-line with an air-intake system of the combustion engine. The turbine drives the compressor, wherein rotation of the compressor wheel enables increase in flow of fresh air into an air intake system. One or more combustion cylinders in the combustion engine receive the fresh air from the air intake system and fuel from a fuel source to generate an air-fuel mixture. The combustion cylinders combust the air-fuel mixture to generate combustion exhaust gas. In certain internal combustion engines, a portion of exhaust gas is recirculated within the internal combustion engines to mix the portion of the exhaust gas and an air-fuel mixture for combustion.
[0003] Typically an engine includes fluid regulation components which are controlled to recirculate a desired portion of the exhaust gas within the engine and emit-out another portion of the exhaust gas from the engine. The amount of exhaust gas that is recirculated within the engine impacts engine performance. The portion of the exhaust gas that is emitted out of the engine includes nitrous oxide and particulate matter. Typically engines need to comply with regulatory emission requirements of a host country. For example, the amount of nitrous oxide and particulate matter should not exceed predefined limits.
[0004] Accordingly, the control of the fluid regulation components impacts the engine performance and the emissions. Typically, the fluid regulation components are independently controlled without considering the impact of controlling one fluid regulation over the other fluid regulation component. Such independent control of the fluid regulation components adversely impacts the engine performance and the emissions.
[0005] Therefore, it would be advantageous to provide a method and system that optimally control fluid regulation components to comply with emission requirements and achieve desired engine performance.
BRIEF DESCRIPTION
[0006] In accordance with one embodiment, an engine system is disclosed. The engine system includes an engine including a first fluid regulation component and a second fluid regulation component operationally coupled to the first fluid regulation component. The engine system includes a processing subsystem operationally coupled to the first fluid regulation component and the second fluid regulation component and configured to obtain one of an amount of opening of the first fluid regulation component and an amount of opening of the second fluid regulation component. The processing subsystem is further configured to determine the amount of opening of the first fluid regulation component when the amount of opening of the second fluid regulation component is obtained. The amount of opening of the first fluid regulation component is determined based on a coupling relationship between the first fluid regulation component and the second fluid regulation component and the amount of opening of the second fluid regulation component. The processing subsystem is further configured to determine the amount of opening of the second fluid regulation component when the amount of opening of the first fluid regulation component is obtained. The amount of opening of the second fluid regulation component is determined based on the coupling relationship between the first fluid regulation component and the second fluid regulation component and the amount of opening of the first fluid regulation component. The processing subsystem is further configured to control the first fluid regulation component and the second fluid regulation component to execute the amount of opening of the first fluid regulation component and the amount of opening of the second fluid regulation component.
[0007] In accordance with another embodiment a method is disclosed. The method includes obtaining one of an amount of opening of a first fluid regulation component and an amount of opening of a second fluid regulation component of an engine. The method further includes determining the amount of opening of the first fluid regulation component when the amount of opening of the second fluid regulation component is obtained. The amount of opening of the first fluid regulation component is determined based on a coupling relationship between the first fluid regulation component and the second fluid regulation component and the amount of opening of the second fluid regulation component. The method further includes determining the amount of opening of the second fluid regulation component when the amount of opening of the first fluid regulation component is obtained. The amount of opening of the second fluid regulation component is determined based on the coupling relationship between the first fluid regulation component and the second fluid regulation component and the amount of opening of the first fluid regulation component. The method further includes controlling the first fluid regulation component and the second fluid regulation component to execute the amount of opening of the first fluid regulation component and the amount of opening of the second fluid regulation component.
DRAWINGS
[0008] These and other features and aspects of embodiments of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
[0009] FIG. 1 is a block diagram of an engine system in accordance with certain embodiments of the present invention;
[0010] Fig. 2 is a block diagram of an engine system that describes an architecture of an engine control unit in accordance with certain embodiments of the present invention; and
[0011] Fig. 3 is a flow chart of a method for controlling emissions levels from an engine to a desired level in accordance with one embodiment of the present invention.
DETAILED DESCRIPTION
[0012] Embodiments of the present invention disclose coupling two or more fluid regulation components of an engine to each other to control amount of emissions from the engine to a desired level. Particularly, embodiments of the present invention disclose controlling two or more fluid regulation components of the engine to control an amount of nitrous oxide and particulate matter emissions from the engine. For example, embodiments of the present invention disclose controlling two or more fluid regulation components to control an amount of exhaust gas recirculated within the engine and an amount of exhaust gas emitted out from the engine. As used herein, the term “fluid regulation component’ is a component that regulates an amount of fluid passing through the component or impacts pressure/flow downstream, or a combination thereof. The fluid regulation components, for example, may be valves, a variable geometry turbine (VGT), or the like.
[0013] Referring now to FIG. 1, a block diagram of an engine system 100 is shown in accordance with certain embodiments of the present invention. The engine system 100 includes an engine 101, an engine control unit 150, and a data repository 152. It should be noted herein that the present system and technique should not be restricted to the design and configuration of the engine 101 shown in Fig. 1 and may vary depending on the application. In one embodiment, the engine 101 includes a plurality of cylinders 102, 104 and an intake manifold 106. In the illustrated embodiment, the plurality of cylinders 102 includes a plurality of donor cylinders and the plurality of cylinders 104 includes a plurality of non-donor cylinders. It should noted that while the embodiments of the present system and technique are explained with reference to the donor cylinders 102 and the non-donor cylinders 104, embodiments of the present system and technique may be applied to engines that do not have separate donor cylinders 102 and the non-donor cylinders 104. The donor cylinders 102 and the non-donor cylinders 104 are operationally coupled to the intake manifold 106. The donor cylinders 102 and the non-donor cylinders 104 are configured to receive air-exhaust gas mixture 108 from the intake manifold 106 and fuel from a fuel source (not shown) resulting in formation of a mixture of fuel and air-exhaust-gas. The mixture of fuel and air-exhaust-gas is combusted in the donor cylinders 102 and the non-donor cylinders 104 to generate donor exhaust gas 110, and non-donor exhaust gas 112 respectively. It should be noted herein that the donor exhaust gas 110 and the non-donor exhaust gas 112 may be interchangeably referred to as exhaust gas 110 and exhaust gas 112 respectively. The non-donor cylinders 104 are operationally coupled to an exhaust manifold 124. The exhaust manifold 124 is configured to receive the non-donor exhaust gas 112 from the non-donor cylinders 104.
[0014] The engine 101 further includes a first fluid regulation component 120 and an exhaust gas recirculation manifold 118 (hereinafter referred to as ‘EGR manifold’). The first fluid regulation component 120, for example, may be a first valve. The donor cylinders 102 are coupled to the EGR manifold 118. The first fluid regulation component 120 is coupled to a first path 123 which extend from the EGR manifold 118 to the intake manifold 106 of the engine 101. The first path 123, for example may be formed by one or more pipes that connect the EGR manifold 118 to the intake manifold 106. The first fluid regulation component 120 is configured to recirculate a first portion 121 of the donor exhaust gas 110 within the engine 101. Specifically, the first fluid regulation component 120 is configured to recirculate the first portion 121 of the donor exhaust gas 110 to the intake manifold 106. The first portion 121 of the donor exhaust gas 110 directed into the intake manifold 106, may also be referred to as ‘recirculated exhaust gas’. The recirculated exhaust gas 121 is cooled by a first heat exchanger 127 before being directed into the intake manifold 106. In certain other embodiments, the first fluid regulation component 120 may recirculate a first portion of exhaust gases 110, 112 generated by all the cylinders of the engine 101.
[0015] The engine 101 further includes a second fluid regulation component 122. The second fluid regulation component 122, for example, may be a second valve. The second fluid regulation component 122 is coupled to a second path 125 that extends from the first path 123 to the exhaust manifold 124. The EGR manifold 118 is operationally coupled to the exhaust manifold 124 via a portion of the first path 123 and the second path 125. The second fluid regulation component 122 is configured to regulate an amount of a second portion 111 of the donor exhaust gas 110 that is directed into the exhaust manifold 124 from the EGR manifold 118. The EGR manifold 118 is configured to direct the second portion 111 of the donor exhaust gas 110 outwards from the engine 101. Accordingly, the second fluid regulation component 122 is configured to regulate the second portion 111 of the donor exhaust gas 110 that is directed or emitted outwards from the engine 101. In certain other embodiments, the second fluid regulation component 122 may be configured to regulate a portion of the exhaust gases 110, 112 generated by all cylinders of the engine 101.
[0016] Furthermore, as previously discussed, the non-donor cylinders 104 are operationally coupled to the exhaust manifold 124 and configured to direct the non-donor exhaust gas 112 into the exhaust manifold 124. The exhaust manifold 124 is configured to receive the second portion 111 of the donor exhaust gas 110 and the non-donor exhaust gas 112 to form a mixture of the second portion 111 of the donor exhaust gas 110 and the non-donor exhaust gas 112. The mixture of the non-donor exhaust gas 112 and the second portion 111 of the donor exhaust gas 110 may be referred to as emission exhaust gas 113.
[0017] The engine 101 further includes turbochargers 114, 116. The turbocharger 114 includes a high pressure turbine 126 and a high pressure compressor 128. The turbocharger 116 includes a low pressure turbine 130 and a low pressure compressor 132. While the illustrated embodiment shows the two turbochargers 114, 116, the number of turbocharges in the engine 101 may vary depending on the application. In certain embodiments, the engine 101 may not include turbochargers. The emissions exhaust gas 113 may be routed through the high pressure turbine 126 and the low pressure turbine 130. Further, the emission exhaust gas 113 is treated by an after treatment system (not shown) to generate a treated-exhaust-gas which is then vented outwards from the engine 101.
[0018] In the illustrated embodiment, the low pressure compressor 132 is configured to intake fresh air 134 from the environment, and increases the pressure of the fresh air 134 to generate a first level pressurized air 138. A second heat exchanger 140 is configured to cool the first level pressurized air 138 to generate a cooled first level pressurized air 142. The high pressure compressor 128 is configured to receive the cooled first level pressurized air 142 and compresses the cooled first level pressurized air 142 to generate a second level pressurized air 144. The second level pressurized air 144 is cooled via a third heat exchanger 146 to generate pressurized air 136. It should be noted herein that the number of heat exchangers used herein to cool air may vary depending on the application.
[0019] The pressurized air 136 is fed to the intake manifold 106. The intake manifold 106 is configured to receive the recirculated exhaust gas 121 based on the opening of the first fluid regulation component 120. The pressurized air 136 and the recirculated exhaust gas 121 results in formation of the air-exhaust gas mixture 108 in the intake manifold 106.
[0020] Furthermore, the exhaust manifold 124 is operationally coupled to the low pressure turbine 130 of the turbocharger 116 via a third fluid regulation component 148. The high pressure turbine 126 is rotatably connected to the high pressure compressor 128 and the low pressure turbine 130 is rotatably coupled to the low pressure compressor 132. The third fluid regulation component 148 is configured to control flow of the emission exhaust gas 113 bypassing the high pressure turbine 126 to achieve desired boost pressure in the intake manifold 106. The pressure of the air-exhaust gas mixture 108 in the intake manifold 106 is referred to as boost pressure.
[0021] The engine control unit 150 is operationally coupled to the engine 101 and the data repository 152. The engine control unit 150, for example, may be one or more processing subsystems, microprocessors, or the like that communicate on a wired or wireless medium with the engine 101. It is noted the engine control unit 150 may perform many other functions apart from the functions described with reference to the embodiments of the present system and method.
[0022] In the illustrated embodiment, the engine control unit 150 is configured to control the first fluid regulation component 120 and the second fluid regulation component 122 to achieve desired emission levels of the engine 101. For example, the engine control unit 150 controls the first fluid regulation component 120 and the second fluid regulation component 122 to control nitrogen oxide (NOx) and particulate matter emissions from the engine 101 to meet emission standards. Particularly, the engine control unit 150 is configured to operationally couple the first fluid regulation component 120 to the second fluid regulation component 122 to achieve desired outputs. Such desired outputs may include desired amount of the recirculated exhaust gas 121, or desired oxygen fraction in the intake manifold 106, or desired boost pressure in the intake manifold 106. An exemplary architecture of the engine control unit 150, and control of the first fluid regulation component 120 and the second fluid regulation component 122 by the engine control unit 150 is explained in greater detail with reference to Fig. 2.
[0023] Referring now to Fig. 2, a block diagram of the engine system 100 that describes an architecture of the engine control unit 150 in accordance with an embodiment of FIG. 1 is shown. Reference numeral 202 is representative of a first module that is configured to determine a desired amount of oxygen fraction 206 in the intake manifold 106 based on one or more operational parameters 204 of the engine. The operational parameters 204, for example, may include engine horsepower, engine speed, and ambient conditions, a maximum cylinder pressure, speed of the turbochargers 114, 116, or the like. The ambient conditions, for example may include pressure, temperature and humidity. The operational parameters 204, for example, may be measured by sensing devices (not shown) disposed on the engine 101 or may be input to the engine control unit 150 by a user based on historical knowledge or after inspection of the engine 101. In one embodiment, the desired amount of oxygen fraction 206 in the intake manifold 106, for example, may be determined by mapping the operational parameters 204 to the desired amount of oxygen fraction 206. In another embodiment, the desired amount of oxygen fraction 206 may be determined by processing a transfer function using the operational parameters.
[0024] The engine control unit 150 further includes a second module 208 communicatively coupled to the first module 202. The second module 208 is configured to determine a desired amount 210 of exhaust gas to be recirculated within the engine 101 based on the desired amount of oxygen fraction 206. As discussed herein, the term “desired amount of exhaust gas recirculated within the engine” refers to an amount of exhaust gas to be recirculated within the engine at a future time stamp for achieving desired amount of emissions. In one embodiment, the desired amount 210 of exhaust gas to be recirculated within the engine 101 may be a desired amount of the recirculated exhaust gas 121. In another embodiment, the desired amount 210 of exhaust gas to be recirculated within the engine 101 may be an amount of a portion of the exhaust gas 110, 112 to be recirculated within the engine 101.
[0025] The second module 208 is further configured to determine a desired boost pressure 212 in the intake manifold based on one or more of the operational parameters 204. In one embodiment, the desired boost pressure 212, for example, may be determined by mapping one or more of the operational parameters 204 to the desired boost pressure 212. In another embodiment, the desired boost pressure 212 may be determined by processing a transfer function using the operational parameters 204.
[0026] Further, the engine control unit 150 includes a first dynamic controller module 214 and a second dynamic controller module 216 operationally coupled to the second module 208. The first dynamic controller module 214 and the second dynamic controller module 216 may be a proportional-integral-derivative controller, a proportional controller, proportional integral controller, proportional derivative controller, a lag compensator, a lead compensator, a lag-lead compensator, a static decoupler, or the like.
[0027] The first dynamic controller module 214 is configured to receive the desired amount 210 of exhaust gas to be recirculated within the engine 101 from the second module 208. Furthermore, the first dynamic controller module 214 is configured to receive a current amount 218 of the exhaust gas recirculated within the engine 101 from the engine 101. As used herein, the term “current amount of exhaust gas recirculated within the engine” refers to an amount of exhaust gas recirculated within the engine 101 at a present/current time stamp. In one embodiment, the current amount 218 of exhaust gas to be recirculated within the engine 101 may be equal to the desired amount of the recirculated exhaust gas 121 at a present time stamp. In another embodiment, the current amount 218 of exhaust gas recirculated within the engine 101 may be equal to the amount of the portion of the exhaust gas 110, 112 recirculated within the engine 101 at a present/current time stamp. The first dynamic controller module 214 is configured to determine an exhaust-gas-recirculation error (not shown) based on the current amount 218 of the exhaust gas recirculated within the engine 101 and the desired amount 210 of the exhaust gas to be recirculated within the engine 101. The first dynamic controller module 214 may determine the exhaust-gas-recirculation error by subtracting the current amount 218 of the exhaust gas recirculated within the engine 101 from the desired amount 210 of the exhaust gas to be recirculated within the engine 101.
[0028] Subsequently the first dynamic controller module 214 is configured to determine an amount 220 of opening of the first fluid regulation component 120 or an amount 222 of opening of the second fluid regulation component 122 based on the exhaust-gas-recirculation error. For example, the first dynamic controller module 214 may determine the amount 220 of opening of the first fluid regulation component 120 or the amount 222 of opening of the second fluid regulation component 122 by mapping the exhaust-gas-recirculation error to the amount 220 of opening of the first fluid regulation component 120 or the amount 222 of the opening of the second fluid regulation component 122. In one embodiment, the first dynamic controller module 214 may store the amount 220 of opening of the first fluid regulation component 120 or the amount 222 of opening of the second fluid regulation component 122 in the data repository 152.
[0029] The engine control unit 150 further includes an exhaust-gas-recirculation coupling module 224 coupled to the first dynamic controller module 214. The exhaust-gas-recirculation coupling module`224 is configured to obtain the amount 220 of opening of the first fluid regulation component 120 or the amount 222 of opening of the second fluid regulation component 122 from the first dynamic controller module 214 or the data repository 152.
[0030] In one embodiment, the exhaust-gas-recirculation coupling module 224 may determine the amount 220 of opening of the first fluid regulation component 120 if the amount 222 of opening of the second fluid regulation component 122 is obtained. The amount 220 of opening of the first fluid regulation component 120 is determined based on a coupling relationship 226 between the first fluid regulation component 120 and the second fluid regulation component 122 and the amount 222 of opening of the second fluid regulation component 122. In another embodiment, the exhaust-gas-recirculation coupling module 224 may determine the amount 222 of opening of the second fluid regulation component 122 if the amount 220 of opening of the first fluid regulation component 120 is obtained. The amount 222 of opening of the second fluid regulation component 122 is determined based on the coupling relationship 226 between the first fluid regulation component 120 and the second fluid regulation component 122 and the amount 220 of opening of the first fluid regulation component 120. The coupling relationship 226, for example, may be at least one of a power law constrained coupling relationship, a sigmoid coupling relationship, a linear coupling relationship, a polynomial coupling relationship, a spline coupling relationship, and a quadratic coupling relationship. An example of a power law constrained coupling relationship, a linear coupling relationship, a spline coupling relationship, or a quadratic coupling relationship may represented by equation (1) based on value of m:
(1)
where A is an amount of opening of the first fluid regulation component 120, B is an amount of opening of the second fluid regulation component 122, m is a real number greater than zero and is representative of an optimization parameter. An example of the sigmoid coupling relationship is represented by equation (2):
(2)
where A is an amount of opening of the first fluid regulation component 120, B is an amount of opening of the second fluid regulation component 122, a, b and c are optimization parameters. The optimization parameters a, b, and c, for example, may be determined by engineering design of experiments or solving a constrained optimization problem. The coupling relationship 226 may be retrieved by the exhaust-gas-recirculation coupling module 224 from the data repository 152. In one embodiment, the coupling relationship 226 may be determined by the engine control unit 150 at the time of commissioning of the engine 101 or after commissioning of the engine 101 and thereafter may be stored in the data repository 152. In one embodiment, the coupling relationship 226 may be determined by generating and solving an unconstrained objective function. In one embodiment, the objective function may define the exhaust-gas-recirculation error as being less than or equal to a first threshold. The first threshold, for example, may be determined by trial and error or design of experiments. In an alternative embodiment, the objective function may be generated to define a pressure differential across the first fluid regulation component 120 and/or the second fluid regulation component 122 which is less than or equal to a second threshold. The second threshold, for example, may be determined by trial and error or design of experiments. An example of the objective function is represented by equation (3):
(3)
where Z is a cost function, is representative of a pressure differential across the first fluid regulation component 120 or a pressure differential across the second fluid regulation component 122, is representative of the current amount 218 of the exhaust gas recirculated within the engine 101, is representative of the desired amount 210 of the exhaust gas to be recirculated within the engine 101, A is representative of the amount of opening of the first fluid regulation component 120, is representative of a lower limit of the amount of opening of the first fluid regulation component 120, is representative of a lower limit of the amount of opening of the second fluid regulation component 122, is representative of an upper limit of the amount of opening of the first fluid regulation component 120, is representative of an upper limit of the amount of opening of the second fluid regulation component 122.
[0031] The current amount 218 of the exhaust gas recirculated within the engine 101 , for example may be determined as a function of the amount 220 of opening of the first fluid regulation component 120 and the amount 222 of opening of the second fluid regulation component 122. The current amount 218 of the exhaust gas recirculated within the engine 101 , for example may be represented by the following equation:
(4)
where A is the amount of opening of the first fluid regulation component 120 and B is the amount of opening of the second fluid regulation component 122.
[0032] The desired amount 210 of the exhaust gas to be recirculated within the engine 101 may be defined as a function of the amount 220 of opening of the first fluid regulation component 120 and/or the amount 222 of opening of the second fluid regulation component 122. The desired amount 210 of the exhaust gas to be recirculated within the engine 101 may be represented by the following equation:
(5)
where a is a constant, and B is the amount of opening of the second fluid regulation component 122.
[0033] Another manifestation of the objective function may define that the pressure differential across the first fluid regulation component 120 or the pressure differential across the second fluid regulation component 122 is a function of the amount 220 of opening of the first fluid regulation component 120 and/or the amount 222 of opening of the second fluid regulation component 122. An example of the third condition wherein g(..) represents a function, is represented by equation (6):
(6)
[0034] Subsequently, the exhaust-gas-recirculation coupling module 224 or the engine control unit 150 is configured to control the engine 101 to control the first fluid regulation component 120 and the second fluid regulation component 122 to execute the amount 220 of opening of the first fluid regulation component 120 and the amount 222 of opening of the second fluid regulation component 122. In other words, the engine control unit 150 is configured to control the first fluid regulation component 120 to open the first fluid regulation component 120 equal to the amount 220 of opening of the first fluid regulation component 120. Similarly, the engine control unit 150 is configured to control the second fluid regulation component 122 to open the second fluid regulation component 122 equal to the amount 222 of opening of the second fluid regulation component 122. The execution of the amount 220 of opening of the first fluid regulation component 120 and the amount 222 of opening of the second fluid regulation component 122 results in regulating amount of emissions from the engine 101 to a desired level.
[0035] Furthermore, as previously noted, the engine system 100 includes the second dynamic controller module 216. The second dynamic controller module 216 is configured to receive the desired boost pressure 212 in the intake manifold 106 from the second module 208. Additionally, the second dynamic controller module 216 is configured to receive a current boost pressure 228 from the engine 101. The current boost pressure 228, for example, may be measured by one or more sensors disposed in the engine 101. Furthermore, the second dynamic controller module 216 is configured to determine a boost-pressure-error 230 based on the current boost pressure and the desired boost pressure 212. For example, the second dynamic controller module 216 may determine the boost-pressure-error 230 by subtracting the current boost pressure 228 from the desired boost pressure 212.
[0036] In the illustrated embodiment, the engine system 100 further includes a boost pressure regulation module 232 coupled to the second dynamic controller module 216. The boost pressure regulation module 232 is configured to receive the boost-pressure-error 230 from the second dynamic controller module 216 and determine an amount of opening of the third fluid regulation component 148 based on the boost-pressure-error 230. The amount of opening of the third fluid regulation component 148 may be determined by a proportional, integral, derivative controller (PID) controller, using gain scheduling. In one embodiment, the boost pressure regulation module 232 is configured to control the third fluid regulation component 148 to achieve the desired boost pressure 212 in the intake manifold 106 so as to regulate the emissions from the engine 101 to a desired level.
[0037] Fig. 3 is a flow chart of a method 300 for controlling emissions levels from an engine to a desired level in accordance with one embodiment of the present invention. At block 302, the coupling relationship may be determined or retrieved from a data repository. The coupling relationship may be determined by an engine control unit. The coupling relationship may be determined by generating and solving an objective function subject to satisfaction of a plurality of constraints that define a plurality of conditions. The objective function, for example, may be similar to the objective function represented by equation (3) and the plurality of conditions may be similar to the equations represented by equations (4)-(6) discussed herein. The coupling relationship, for example may include at least one of a power law constrained coupling relationship, a sigmoid coupling relationship, a linear coupling relationship, a polynomial coupling relationship, a spline coupling relationship and a quadratic coupling relationship.
[0038] Subsequently at block 304, one of the amount of opening of a first fluid regulation component and the amount of opening of a second fluid regulation component is obtained. The amount of opening of the first fluid regulation component or the amount of opening of the second fluid regulation component may be obtained from the data repository or a dynamic controller module. At block 306, a check is performed to determine whether the amount of opening of the first fluid regulation component or the amount of opening of the second fluid regulation component is obtained. At block 306, if the amount of opening of the first fluid regulation component is obtained, then the control is transferred to block 308. Again at block 306, if the amount of opening of the second fluid regulation component is obtained, then the control is transferred to block 310.
[0039] At block 308, the amount of opening of the first fluid regulation component is determined if the amount of opening of the second fluid regulation component is obtained. The amount of opening of the first fluid regulation component may be determined based on the coupling relationship between the first fluid regulation component and the second fluid regulation component and the amount of opening of the second fluid regulation component.
[0040] At block 310, the amount of opening of the second fluid regulation component may be determined if the amount of opening of the first fluid regulation component is obtained. The amount of opening of the second fluid regulation component may be determined based on the coupling relationship between the first fluid regulation component and the second fluid regulation component and the amount of opening of the first fluid regulation component.
[0041] Furthermore, at block 312 the first fluid regulation component and the second fluid regulation component is controlled to execute the amount of opening of the first fluid regulation component and the amount of opening of the second fluid regulation component. The execution of the amount of opening of the first fluid regulation component and the amount of opening of the second fluid regulation component results in regulating amount of emissions from the engine to a desired level.
[0042] Embodiments of the present method and system control an amount of exhaust gas recirculation and an amount of exhaust gas emitted out of an engine by controlling fluid regulation components so as to control amount of emissions from the engine to a desired level. Particularly, the fluid regulation components of an engine are coupled to each other to control the amount of emissions from the engine. For example, the exemplary embodiments disclose determining an amount of opening of first and second fluid regulation components based on a coupling relationship between the first fluid regulation component and the second fluid regulation component.
[0043] While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.