Estimation of instantaneous indicated torque in multicylinder engines

• US 5,771,482 A
• Filed: 12/15/1995
• Issued: 06/23/1998
• Est. Priority Date: 12/15/1995
• Status: Expired due to Fees

• Current Assignee: Ohio State University, Ohio University
• Original Assignee: Ohio State University
• Inventors: Rizzoni, Giorgio
• Primary Examiner(s): LOUIS JACQUES, JACQUES H
• Application Number:
  US08/573,327
• Time in Patent Office: 921 Days
• Field of Search: 364/431.03, 364/431.07, 364/431.08, 364/431.01, 364/550, 364/551.01, 364/431.061, 364/431.053, 73/117.3, 73/116, 73/115, 73/660, 123/479, 123/630, 123/425, 123/627, 123/655, 123/416, 123/435, 123/436, 123/492, 123/481, 123/419, 123/676, 123/417, 123/478, 324/388, 324/399, 324/379
• US Class Current: 701/101
• CPC Class Codes: F02D 2041/1415 using a state feedback or a state space representation
• CPC Class Codes: F02D 2041/1416 Observer
• CPC Class Codes: F02D 2041/1433 using a model or simulation of the system
• CPC Class Codes: F02D 2041/1434 Inverse model
• CPC Class Codes: F02D 2041/288 for performing a transformation into the frequency domain, e.g. Fourier transformation
• CPC Class Codes: F02D 2200/1004 Estimation of the output torque
• CPC Class Codes: F02D 41/1401 characterised by the control or regulation method F02D41/1473, F02D41/1477 take precedence
• CPC Class Codes: G01L 3/00 Measuring torque, work, mechanical power, or mechanical efficiency, in general
• CPC Class Codes: G01M 15/042 by monitoring a single specific parameter not covered by groups G01M15/06 - G01M15/12

Abstract

A method and apparatus for estimating instantaneous torque in an internal combustion engine includes a comprehensive model of internal combustion engine dynamics. Instantaneous net torque is estimated using a model which describes the relationship between engine indicated torque and crankshaft angular velocity. The first method and apparatus perform an explicit model inversion to solve for individual cylinder combustion torques. The second method and apparatus perform an implicit model inversion for reconstructing combustion torques produced by individual combustion events in an internal combustion engine. Unknown input observers are used in the implicit model inversion. The individual cylinder combustion torques are monitored as an indication of engine performance.

Claims

1. A method of reconstructing combustion torques produced by individual combustion events in an internal combustion engine, the method comprising the steps of:

obtaining a first set of measured outputs including a first set y of measured outputs from at least one of an engine and drivetrain of the internal combustion engine by determining instantaneous angular velocity of the at least one of the engine and drivetrain at a first set of preselected points along the at least one of the engine and drivetrain;

providing a dynamic mathematical model of an engine assembly of the internal combustion engine relating a fist set of net individual cylinder torques to a first set of outputs of the internal combustion engine, by providing an unknown-input state space model;

space="preserve" listing-type="equation">x(t)=f(x(t), u(t), d(t))

space="preserve" listing-type="equation">y(t)=g(x(t), u(t), d(t))

relating a first set of unknown combustion torques d(t) to a first set of measured outputs y(t), wherein x(t) is a state vector and u(t) is a known input vector;

reconstructing a first set of estimated net individual cylinder torques by inverting said mathematical model and applying said first set of measured outputs to the inverted mathematical model according to an implicit inversion of said unknown-input state space model based on at least one of an input observer and input estimates; and

,

performance of the internal combustion engine based upon the estimated net individual cylinder torques.

2. The method according to claim 1 wherein the step of providing said unknown-input state space model includes providing a linear unknown-input observer model;

space="preserve" listing-type="equation">x(t)=A x(t)+Bu(t)+D d(t)

space="preserve" listing-type="equation">y(t)=C x(t)

wherein D is a constant matrix associated with a q-dimensional unknown input vector d, x is states of the unknown-input state space model, y is a measured output vector, u is a measured input vector, A represents system dynamics, B represents known inputs distribution, and C represents an output measurement matrix.

3. The method according to claim 2 wherein the step of obtaining said first set y of measured outputs includes determining an angular position of said at least one of said engine and drivetrain of the internal combustion engine.

4. The method according to claim 2 wherein the step of obtaining said first set y of measured outputs includes determining an angular torque of said at least one of said engine and drivetrain of the internal combustion engine.

5. The method according to claim 2 wherein the step of obtaining said first set y of measured outputs includes determining an angular acceleration of said at least one of said engine and drivetrain of the internal combustion engine.

6. The method according to claim 2 wherein the step of obtaining said first set y of measured outputs includes determining a shaft torque measurement of said at least one of said engine and drivetrain of the internal combustion engine.

7. The method according to claim 2 wherein the step of obtaining said first set y of measured outputs includes determining at least one of an angular position, an angular torque, an angular acceleration and a shaft torque measurement of said at least one of said engine and drivetrain of the internal combustion engine.

8. A method of reconstructing combustion torques produced by individual combustion events in an internal combustion engine, the method comprising the steps of:

obtaining a first set of measured outputs Y(s) from a rotating member in the internal combustion engine, said step of obtaining including the substep of determining at least one of an angular position, an angular torque, an angular acceleration and a shaft torque measurement of at least one of an engine and a drivetrain of the internal combustion engine;

providing a dynamic mathematical model of an engine assembly of the internal combustion engine relating a fist set of net individual cylinder torques to a first set of outputs of the internal combustion engine, by providing a transfer function model H(s) of the internal combustion engine, the transfer function odel H(s) relating a first set of net individual cylinder torques X(s) to said first set of outputs Y(s) of the internal combustion engine;

reconstructing a first set of estimated net individual cylinder torques by inverting said mathematical model and applying said first set of measured outputs to the inverted mathematical model, including explicitly inverting said transfer function model H(s) and applying said first set of measured outputs to the inverted model according to X(s)=H^-1 (s) Y(s); and

,

monitoring performance of the internal combustion engine based upon the estimated net individual cylinder torques.

9. A method of estimating combustion torques produced by combustion events in an internal combustion engine, the method comprising:

sampling a first set of measured outputs from a moving member in the internal combustion engine;

providing an inverted mathematical model of an engine rotating assembly of the internal combustion engine relating a first set of net individual cylinder torques to a first set of outputs of the internal combustion engine, said step of providing including providing an unknown-input state space model;

space="preserve" listing-type="equation">x(t)=f(x(t), u(t), d(t))

space="preserve" listing-type="equation">y(t)=g(x(t), u(t), d(t))

relating a first set of combustion torques d(t) to a first set of outputs y(t), wherein x(t) is a state vector and u(t) is a known input vector;

reconstructing a first of estimated net individual cylinder torques by applying said first set of measured outputs to the inverted mathematical model; and

,

monitoring performance of the internal combustion engine based upon the estimated net individual cylinder torques.

10. The method according to claim 9 wherein the step of providing said unknown-input state space model includes providing a linear unknown-input observer model:

space="preserve" listing-type="equation">x(t)=A x(t)+Bu(t)+Dd(t)

space="preserve" listing-type="equation">y(t)=C x(t)

wherein D is a constant matrix associated with a q-dimensional unknown input vector d, x is states of the unknown-input state space model, y is a measured output vector, u is a measured input vector, A represents system dynamics, B represents known inputs distribution, and C represents an output measurement matrix.

11. A method of estimating combustion torques produced by combustion events in an internal combustion engine to monitor performance of the internal combustion engine, the method comprising:

sampling a first set of measured outputs from a moving member in the internal combustion engine;

providing an inverted transfer function mathematical model H^-1 (s) of an engine rotating assembly of the internal combustion engine, the inverted transfer function mathematical model relating a first set of net individual cylinder torques X(s) to a first set of measured outputs Y(s) of the internal combustion engine;

reconstructing a first of estimated net individual cylinder torques by applying said first set of measured outputs Y(s) to the inverted mathematical model according to X(s)=H^-1 (s) Y(s), wherein said step of reconstructing including the substep of

forming a plurality of look-up tables, each of the plurality of look-up tables containing transfer function model parameters relating a respective plurality of first sets of net individual cylinder torques with a corresponding plurality of first sets of measured outputs of the internal combustion engine; and

monitoring the performance of the internal combustion engine based on the estimated combustion torques.

12. The method according to claim 11 wherein the step of forming said plurality of look-up tables includes forming each of the plurality of look-up tables to reflect a different operating condition of the internal combustion engine.

13. The method according to claim 12 wherein the step of forming each of the plurality of look-up tables includes forming each of the plurality of look-up tables to reflect a different operating condition of the internal combustion engine including at least an engine mean speed condition and throttle position condition.

14. The method according to claim 11 wherein the step of forming said plurality of look-up tables includes forming each of the plurality of look-up tables to reflect a different state of an operating condition of the internal combustion engine.

15. The method according to claim 14 wherein the step of forming each of the plurality of look-up tables includes forming each of the plurality of look-up tables to reflect a different state of a single operating condition of the internal combustion engine including an engine mean speed condition and throttle position condition.

16. An apparatus for reconstructing combustion torques produced by individual combustion events in an internal combustion engine, the apparatus comprising:

a set of sensors for obtaining a first set of measured outputs from a rotating member in the internal combustion engine, said set of sensors including means for obtaining a first set y of measured outputs from at least one of an engine and drivetrain of the internal combustion engine by determining instantaneous angular velocity of the at least one of the engine and drivetrain at a first set of preselected points along the at least one of the engine and drivetrain;

mathematical model providing means for providing a dynamic mathematical model of an engine rotating assembly of the internal combustion engine, the mathematical model relating a is first set of net individual cylinder torques to a first set of outputs of the internal combustion engine, said mathematical model providing means including means for providing an unknown-input state space model;

space="preserve" listing-type="equation">x(t)=f(x(t), u(t), d(t))

space="preserve" listing-type="equation">y(t)=g(x(t), u(t), d(t))

relating a first set of unknown combustion torques d(t) to a first set of measured outputs y(t), wherein x(t) is a state vector and u(t) is a known input vector; and

,

reconstructing means for reconstructing a first set of estimated net individual cylinder torques by inverting said mathematical model and applying said first set of measured outputs to the inverted mathematical model, said reconstructing means including means for performing an implicit inversion of said unknown-input state space model using at least one of an input observer and input estimates.

17. An apparatus for reconstructing combustion torques produced by individual combustion events in an internal combustion engine, the apparatus comprising:

a set of sensors for obtaining a first set of measured outputs including means for obtaining a first set of measured outputs Y(s) from said rotating member in an internal combustion engine;

mathematical model providing means for providing a dynamic mathematical model of an engine rotating assembly of the internal combustion engine, said mathematical model providing means including means for providing a transfer function model H(s) of the internal combustion engine, the transfer function model H(s) relating said first set of net individual cylinder torques X(s) to a first set of outputs Y(s) of the internal combustion engine; and

,

reconstructing means for reconstructing a first set of estimated net individual cylinder torques by inverting said mathematical model and applying said first set of measured outputs to the inverted mathematical model, said reconstructing means including means for explicitly inverting said transfer function model H(s) and applying said first set of measured outputs to the inverted model according to X(s)=H^-1 (s) Y(s).