Predictive analysis method and system for engine performance and control program for use in the same

• US 20040220716A1
• Filed: 02/03/2004
• Published: 11/04/2004
• Est. Priority Date: 02/05/2003
• Status: Active Grant

• Current Assignee: Mazda Motor Corporation
• Original Assignee: Mazda Motor Corporation
• Inventors: Ueki, Yoshiharu, Yokohata, Hideaki
• Granted Patent: US 7,017,399 B2
• Time in Patent Office: Days
• US Class Current: 701/102
• CPC Class Codes: G05B 17/02 electric

Abstract

In a computer system for analyzing the flow of an intake/exhaust gas of, for example, a four-cycle multi-cylinder engine through application of CFD, the dimension of a space where the flow of the intake/exhaust gas is analyzed can be selected with respect to each of four processes, that is, intake, compression, expansion and exhaust processes, of each cylinder (in selecting step S1), and a physical model for simulating the flow of the intake/exhaust gas from a part of an intake system to a part of an exhaust system of the engine in the dimension selected with respect to each of the four processes is set (in model setting steps S2, S31, S41 and S51). The flow of the intake/exhaust gas is subjected to a CFD operation using the physical model, and chemical reactions caused in combustion is simulated (in operating steps S33, S43 and S53), so as to output an output about engine performance on the basis of the results of these simulation operations. Thus, while keeping sufficiently high accuracy in the analysis, time required for the CFD operation can be reduced as much as possible, resulting in improving the utility as a design/development tool.

Claims

1. A predictive analysis method for predicting performance of an engine by analyzing movement of a working fluid of the engine through application of CFD, comprising the steps of:

dividing a combustion cycle of the engine into four processes of intake, compression, expansion and exhaust processes, and setting, with respect to each of said four processes, a dimension of a space where the movement of said working fluid is analyzed;

analyzing the movement of said working fluid at least from a part of an intake system to a part of an exhaust system of the engine by performing a CFD operation in said dimension having been set with respect to each of said four processes; and

predicting the performance of the engine on the basis of a result of analysis.

2. A predictive analysis system for predicting performance of an engine by analyzing movement of a working fluid of the engine through application of CFD, comprising:

selecting means for allowing an operator to select a dimension of a space where the movement of said working fluid is analyzed with respect to each of four processes of intake, compression, expansion and exhaust processes in a combustion cycle of the engine;

model setting means for setting a physical model used for simulating the movement of said working fluid at least from a part of an intake system to a part of an exhaust system of the engine in said dimension selected with respect to each of said four processes; and

operating means for describing the movement of said working fluid of the engine through a CFD operation using said physical model.

3. The predictive analysis system of claim 2,

wherein it is selectable by said selecting means whether the movement of said working fluid is assumed to be a one dimensional flow or a three dimensional flow in said intake process of the engine.

4. The predictive analysis system of claim 2,

wherein it is selectable by said selecting means whether the movement of said working fluid is assumed to be a one dimensional flow or a three dimensional flow in said exhaust process of the engine.

5. The predictive analysis system of claim 2,

wherein it is selectable by said selecting means whether the movement of said working fluid is assumed to be a one dimensional flow or a three dimensional flow in said intake and exhaust processes of the engine, and

said model setting means sets a physical model in said selected dimension with respect to said intake or exhaust process of the engine and sets a zero dimensional physical model with respect to said compression and expansion processes assuming that said working fluid does not move at least in a combustion chamber of the engine in said compression and expansion processes.

6. The predictive analysis system of claim 2,

wherein said model setting means sets a three dimensional physical model for a section of a portion extending from at least a part of the intake system to a part of the exhaust system of the engine and sets a one dimensional physical model for another section of said portion.

7. The predictive analysis system of claim 2, further comprising a database where design CAD data of engines are accumulated,

wherein said model setting means constructs a physical model on the basis of data read from said database.

8. The predictive analysis system of claim 2, further comprising a database of component models each of which simulates a basic shape of a given section for allowing said working fluid of the engine to pass and is changeable in a dimension, a shape and at least one of physical characteristic values,

wherein said model setting means accepts input of data about the dimension and at least one of physical characteristic values of said given portion, reads a corresponding component model from said database, and constructs a physical model for use in the CFD operation by modifying said component model on the basis of said input data.

9. The predictive analysis system of claim 2,

wherein when said dimension of the space where the movement of said working fluid of the engine is simulated is changed, said operating means transforms values of variables used for describing the movement of said working fluid in accordance with the change of said dimension.

10. The predictive analysis system of claim 2, further comprising outputting means for outputting an output about the performance of the engine on the basis of a result of the CFD operation performed by said operating means.

11. A control program for a computer system for predicting performance of an engine by analyzing movement of a working fluid of the engine through application of CFD, comprising:

a selecting step of selecting a dimension of a space where the movement of said working fluid is analyzed with respect to each of four processes of intake, compression, expansion and exhaust processes in a combustion cycle of the engine;

a model setting step of setting a physical model for use in simulating the movement of said working fluid from at least a part of an intake system to a part of an exhaust system of the engine in said dimension selected with respect to each of said four processes; and

an operating step of describing the movement of said working fluid of the engine by a CFD operation using said physical model.

12. The control program of claim 11,

wherein it is selectable in the selecting step whether the movement of said working fluid is assumed to be a one dimensional flow or a three dimensional flow in said intake process of the engine.

13. The control program of claim 11,

wherein it is selectable in the selecting step whether the movement of said working fluid is assumed to be a one dimensional flow or a three dimensional flow in said exhaust process of the engine.

14. The control program of claim 11,

wherein it is selectable in the selecting step whether the movement of said working fluid is assumed to be a one dimensional flow or a three dimensional flow in said intake and exhaust processes of the engine, and

in the model setting step, a physical model of said selected dimension is set with respect to said intake or exhaust process of the engine and a zero dimensional physical model is set with respect to said compression and expansion processes by assuming that said working fluid does not move at least in a combustion chamber of the engine in said compression and expansion processes.

15. The control program of claim 11,

wherein in the model setting step, a three dimensional physical model is set for a section of a portion extending from at least a part of the intake system to a part of the exhaust system of the engine and a one dimensional physical model is set for another section of said portion.

16. The control program of claim 11,

wherein in the model setting step, desired data is read from a database where design CAD data of engines are accumulated, and a physical model is constructed on the basis of data read from said database.

17. The control program of claim 11,

wherein a database of component models each of which simulates a basic shape of a given section for allowing said working fluid of the engine to pass and is changeable in a dimension, a shape and at least one of physical characteristic values is prepared,

said control program further comprises an inputting step of inputting data about the dimension and at least one of physical characteristic values of said given section, and

in the model setting step, a corresponding component model is read from said database, and a physical model for use in the CFD operation is constructed by modifying said component model on the basis of said input data.

18. The control program of claim 11,

wherein when said dimension of the space where the movement of said working fluid of the engine is simulated is changed, the operating step includes a data transforming sub-step of transforming values of variables used for describing the movement of said working fluid in accordance with the change of said dimension.

19. The control program of claim 11, further comprising an outputting step of outputting an output about the performance of the engine on the basis of a result of the CFD operation performed in the operating step.