WO2004057165A2

WO2004057165A2 - Control of an internal combustion engine

Info

Publication number: WO2004057165A2
Application number: PCT/IB2003/006031
Authority: WO
Inventors: Cornelius Burger
Original assignee: Cornelius Burger
Priority date: 2002-12-20
Filing date: 2003-12-17
Publication date: 2004-07-08
Also published as: AU2003294152A1; WO2004057165A3; AU2003294152A8

Abstract

A method of modifying an output signal (34) of an electronic engine control unit (32) controllable connected to an internal combustion engine, including receiving at least one sensor signal (12.6, 12.8), representative of an engine performance parameter, from at least one sensor, modifying the sensor signal (12.2, 12.4) by means of a control algorithm (44, 46), and sending to an input of an engine control unit (32) the modified sensor signal (14). The engine control unit (32) output signal (34) is thereby varied to modify the performance of the engine, via the engine control unit (32).

Description

CONTROL OF AN INTERNAL COMBUSTION ENGINE

THIS INVENTION relates to the control of an internal combustion engine. It relates more particularly to a method of modifying an output signal of an engine control unit, to a signal modification accessory, and to an engine control installation.

In the operation of an internal combustion engine controlled by an engine control unit (ECU), the ECU is typically programmed to provide predetermined levels of output signals in response to predetermined levels of input signals received from sensors sensing engine performance and also, optionally, environmental conditions. ECU'S are typically designed to optimise certain engine performance characteristics such as exhaust gas emissions, but not necessarily to optimise certain other engine performance characteristics such a fuel consumption or power output.

In the operation of an internal combustion engine, the invention provides a method of modifying an output signal of an electronic engine control unit (ECU) controllably connected to an internal combustion engine, which method includes receiving at least one sensor signal, representative of an engine performance parameter, from at least one sensor; modifying the sensor signal by means of a control algorithm; and sending to an input of the engine control unit the modified sensor signal, thereby to vary the engine control unit output signal and thus to modify the performance of the engine, via the engine control unit.

The method may include supplying to the ECU a feedback signal representative of engine performance as a result of the modification. If necessary, the feedback signal may be used still further to modify the input signal to the ECU, and hence the output signal of the ECU.

Further in accordance with the invention, there is provided a signal modification^' accessory (SMA), connectable between at least one engine sensor and an engine control unit (ECU) controllably connected to an internal combustion engine, the signal modification accessory including a signal modification accessory input terminal connectable to the engine sensor; a signal modification accessory output terminal connectable to at least one input terminal of the engine control unit; and a processor intermediate the signal modification accessory input terminal and the signal modification accessory output terminal, the processor being operable to generate a modified signal at the signal modification accessory output terminal in accordance with a value of a signal received at the signal modification accessory input terminal, thereby to control performance of the engine via the ECU. Even further in accordance with the invention, there is provided an engine control installation, which includes at least one sensor for measuring at least one engine parameter; a signal modification accessory (SMA) having a signal input terminal connected to the sensor, thereby to receive a signal from the sensor, and, in response, to generate a modified sensor signal at a signal output terminal; and an engine control unit (ECU) having an input terminal connected to the signal output terminal of the signal modification accessory for receiving the modified sensor signal and having at least one output terminal controllably connected to an engine, for controlling the operation of the engine.

The sensor from which the sensor signal originates may be an air mass (A/M) sensor provided in an inlet manifold to the engine, a manifold ambient pressure (MAP) sensor provided in the inlet manifold of the engine, and a throttle position (TP) sensor, all of which may be used to measure the engine load, a lambda (λ) sensor provided in an exhaust path of the engine, a revolutions per minute (RPM) counter, a crankshaft position sensor, an exhaust gas temperature (EGT) sensor, an engine temperature sensor, or the iike, for sensing the engine condition.

If desired, a sensor may be retrofitted to monitor a particular engine performance parameter, such as exhaust gas temperature or crankshaft position, if such a sensor has not been factory fitted during manufacture of the engine. If desired, the method may include sensing at least one environmental condition, such as ambient temperature or pressure, and feeding the information sensed to the control algorithm.

The installation may then include an environmental condition sensor such as a temperature sensor, barometer, or the like.

The A/M sensor provides an indication of the amount of air that is fed into the engine. The MAP sensor provides an indication of the engine load by measuring the reduction of ambient pressure in the inlet manifold. The TP sensor also provides an indication of the engine load as it indicates the desired load to the engine as deduced from the throttle position. A λ value provided by the λ sensor is an indication of the air to fuel ratio fed into the engine, and the RPM counter counts the number of engine revolutions per minute.

The sensor signal may be modified by use of one or more algorithms stored in the processor of the SMA. Thus, the processor may be programmed selectively to use a selected algorithm to generate the modified output signal. By modifying the sensor signal to the ECU, the output signal from the ECU is modified.

The processor may be programmed with an open loop control algorithm, operable, when executed, to generate a modified sensor output signal at the SMA output terminal in accordance with a value of each particular sensor input signal received at the SMA input terminal. The method of modifying an output signal of an electronic engine control unit may thus include modifying the sensor signal by means of an open loop control algorithm which generates a simulated sensor output signal in response to at least one sensor signal received.

For example, the processor may be programmed to generate predetermined λ and A M output signals for a specific RPM of the engine and for a specific MAP or TP.

The sensor output signals may be pre-programmed while the engine is operationally tested in an engine test environment, e.g. on a dynamometer.

Instead or in addition, the processor may be programmed with a closed loop control algorithm, operable, when executed, to generate a modified sensor output signal at the signal modification accessory output terminal to obtain a desired sensor input signal value at the input terminal.

By modifying the input to, and hence, the output from the ECU, the engine performance can be changed so as to obtain a desired sensor input signal at the SMA signal input terminal. For example, the processor may be programmed initially to generate a pre-programmed output signal such as a particular λ signal for a specific engine RPM and for a specific MAP/TP, but the λ output signal at the SMA signal output terminal may automatically be adjusted by the processor during operation of the engine to change the performance of the engine, and thereby to obtain the desired λ input signal at the SMA signal input terminal. Hence, the processor unit is controlling the engine in a "closed loop" feedback path configuration.

The method of modifying an output signal of an electronic engine control unit may thus include modifying the sensor signal by means of a closed loop algorithm which generates a simulated sensor output signal to obtain a desired sensor input signal.

The processor may be programmed selectively to switch between the open loop and closed loop control algorithms.

The method of modifying an output of an ECU may include mapping a set of simulated sensor output signal values to a set of sensor input signal values.

The processor may thus include storage means operable to store the set of simulated sensor output signal values, which may be mapped in, a single-dimensional array to the set of sensor input signal values, to serve as an input to the control algorithm.

Alternatively, or in addition, the storage means may be operable to store at least one set of simulated sensor output signal values, mapped in a multi-dimensional array to at least two sets of sensor input signal values, to serve as an input to the control algorithm. In the method of modifying an output of an electronic control unit by means of a closed loop algorithm, the desired sensor input signal may originate from one sensor and the sensor signal that is modified may originate from another signal.

In particular, the desired sensor signal may originate from an exhaust gas temperature ^■ sensor and the sensor signal that is modified may originate from a lambda sensor.

Further in accordance with the invention, there is provided a method of modifying the performance of an internal combustion engine during operation, which method includes measuring the temperature of exhaust gas from the internal combustion engine; and adjusting an air/fuel ratio supplied to the internal combustion engine to obtain a desired exhaust gas temperature.

An embodiment of the invention will now be described, by way of example only, with reference to the following diagrammatic drawings.

In the drawings, Figure 1 shows a schematic circuit diagram of a signal modification accessory in accordance with the invention;

Figure 2 shows a functional block diagram of the signal modification accessory implementing an "open loop" control algorithm in accordance with the invention; and Figure 3 shows a functional block diagram of the signal modification accessory implementing a "closed loop" control algorithm in accordance with the invention.

In the drawings reference numeral 10 generally indicates a signal modification accessory (SMA) in accordance with the invention.

As shown in Figure 1 , the SMA 10 includes a set of signal input terminals 12 (shown in broken line), a set of signal output terminals 14 (shown in broken line), and a processor 16. The set of signal input terminals 12 includes input terminals (12.2, 12.4, 12.6, and 12.8) which are connectable to various sensors which sense operating parameters of an internal combustion engine (not shown), during operation. Additional sensors (not shown) may optionally be provided to sense environmental conditions.

Input terminal 12.2 is connectable to a lambda (λ) sensor, terminal 12.4 is connectable to an air mass (A/M) sensor or to a manifold ambient pressure (MAP) sensor, terminal 12.6 is also connectable to a manifold ambient pressure (MAP) sensor, or a throttle position (TP) sensor which provides an indication of the engine load, and terminal 12.8 is connectable to a revolutions per minute (RPM) counter. The RPM counter generates a digital signal from a hall-effect sensor, a magnetic sensor, or the like, used to determine the angular velocity of the crankshaft.

The set of signal output terminals 14 provides output terminals which are connectable to inputs of an engine control unit (ECU) 32 (see Figures 2 and 3) of the internal combustion engine. The set of signal output terminals 14 includes a λ output terminal 14.2 which is connectable to a λ input of the ECU, an A/M output terminal 14.4 which is connectable to an A/M input of the ECU, or to a manifold ambient pressure (MAP) input of the ECU, and two digital output terminals 14.6 and 14.8, which are for example connectable to fuel injectors or to a solenoid gas valve, operable to control a supply of NOx to the engine. Output terminals 14.6 and 14.8 are not shown in Figure 2 and 3.

The processor 16 is programmed with a control algorithm to generate modified signals at the set of signal output terminals 14 in response to signals received at the set of signal input terminals 12.

The set of signal input terminals 12 is connected through signal conditioning circuitry 18 (shown in broken line), comprising zener diodes, resistors, and unity gain amplifiers, to an analog input of an Analog-to-Digital

(A/D) converter 20. The signal conditioning circuitry 18 for the RPM counter input terminal 12.8 includes a resistor and an opto-coupler circuit, which, when operational, provides a shaped digital pulse stream, to an input of the processor 16.

Digital outputs from the A/D converter 20 are connected to inputs of the processor 16. Digital outputs from the processor 16 are connected to digital inputs of a Digital-to-Analog (D/A) converter 22. Analog outputs of the D/A converter 22 are connected through an amplification stage 24 (shown in broken line) to the set of signal output terminals 14. The SMA 10 also includes power regulation circuitry 26 for supplying power, at a regulated voltage to the SMA circuitry, from a regular vehicle battery. It further includes a serial communication port 28 for communicating with a computer (not shown) during programming of the processor 16, and a set of interface terminals 30, used in conjunction with the communication port 28, when communicating with the computer via a serial port on the computer.

Figure 2 shows a functional block diagram of an engine control installation 40 which includes the SMA 10 connected, as an accessory, to the engine control unit 32. In addition, SMA 10, shown in Figure 2, includes an input terminal 12.10, an output terminal 14.10 and a pulse processor 50, operably connected between the input- and output terminals 12.10 and 14.10. The terminals 12.10, 14.10 are not shown in Figure 1.

The SMA 10 shown in Figure 2 is programmed with an "open loop" control algorithm. A lambda λ sensor, an air mass (A/M) sensor, a revolutions per minute (RPM) counter, a manifold ambient pressure (MAP) / throttle position (TP) sensor and an ignition pulse sensor, (none of which is shown) are connected to SMA signal input terminals 12.2, 12.4, 12.6, 12.8 and 12.10 respectively. In another embodiment, a manifold ambient pressure (MAP) sensor instead of the A/M sensor is connected to SMA signal input terminal 12.4. In yet another embodiment, an exhaust gas temperature sensor is connected to the SMA signal input terminal 12.6.

The signal output terminals 14.2, 14.4 and 14.10 are connected to the λ, the A/M, and the ignition pulse inputs of the ECU 32. Outputs 34.2, 34.4 and 34.6 from the ECU 32 are controllably connected to the engine (not shown). Reference numeral 42 represents a two-dimensional array used as a lookup table in which is stored sets of simulated λ and A/M sensor output signal values, mapped to sets of RPM and MAP/TP sensor input signal values. The RPM and MAP/TP sensor input signal values are received on terminals

12.6 and 12.8, and the simulated λ and A/M (or MAP) sensor output signal values are generated on lines 12.21 and 12.41 , respectively. Blocks 44 and 46 are signal addition operators which add the simulated λ and A/M (or MAP) signals received on lines 12.21 and 12.41 to the λ and A/M (or MAP) signals read from the engine into the input terminals 12.2 and 12.4, to generate λ and

A M (or MAP) signal output values at terminals 14.2 and 14.4 which are connected to the ECU 32. The λ and A/M (or MAP) signals received on terminals 12.2 and 12.4 are therefore modified before being sent to the ECU 32 via output terminals 14.2 and 14.4. Hence, output signals 34.2 and 34.4 of the ECU 32 are modified by the modification of the input signals received on the

SMA terminals 12.2 and 12.4. In addition, the ignition pulse received on input terminal 12.10 is read into the SMA 10 and is fed into the pulse processor 50 which is operable to modify the ignition pulse, for example by retarding or advancing the pulse in a following ignition cycle.

Figure 3 shows a functional block diagram of an engine control installation 40 similar to the engine control installation in Figure 2, but the SMA 10 shown in Figure 3 is programmed with a "closed loop" control algorithm. The same numerals have been used to refer to the same, or like components. Reference numeral 42 again represents a two-dimensional array used as a look-up table that generates simulated λ and A/M (or MAP) sensor output signal values on lines 12.21 and 12.41 respectively for each value of RPM and MAP/TP sensor input signal values received on terminals 12.8 and 12.6. The λ and A/M (or MAP) sensor output signal values 12.21 and 12.41 , instead of being fed directly into the signal addition operator 44, are sent through a feedback control algorithm 48 in which is stored a desired λ sensor input signal value.

The feedback control algorithm also reads the sensor output signals from the λ and A/M (or MAP) sensor input signals on terminals 12.2 and 12.4 along lines 12.22 and 12.42. The combination of the two-dimensional array 42 and the feedback from the λ and A/M (or MAP) sensors is used to generate the modified sensor output signal values on line 12.211 and 12.411 which are sent to the signal addition operators 44 and 46. The feedback control algorithm 48 may be tuned to adjust the λ and A/M (or MAP) sensor output signal values at the output terminals 14.2 and 14.4, thereby to modify the outputs 34.2 and 34.4 of the ECU 32 so that the engine (not shown) is controlled to obtain the desired λ values at the input terminals 12.2 and 12.4.

In another embodiment of the engine control installation 40 shown in Figure. 3, a manifold ambient pressure (MAP) sensor instead of the A/M sensor is connected to SMA signal input terminal 12.4. In yet another embodiment, an exhaust gas temperature sensor is connected to the SMA signal input terminal 12.6. In this embodiment, the λ sensor output signal value is adjusted to obtain a desired exhaust gas temperature. The closed loop control algorithm, as implemented in the feedback control algorithm 48 for the A/M (or MAP) signal value, controls the SMA 10 to obtain the desired sensor input signal value for λ by means of the following formula: Δ = Δp + K (current λ - desired λ) / desired λ where:

Δ = new modification to output (to be added to the sensor input signal value (via 12.411)),

Δp = previous modification to output, K = control constant.

The closed loop control algorithm, as implemented in the feedback control algorithm 48 which uses λ sensor input signals can also be used to control the λ output signal value at 14.2, via 12.211. Alternatively the feedback control algorithm 48 can control the λ output signal value at 14.2 via 12.211 to be stoichiometric, i.e. λ = 1.

The values used by the feedback control algorithm 48 to obtain the desired λ value, are stored by the processor. Thus, when using the "closed loop" algorithm, the SMA 10 is capable of "learning" which values provided the desired λ value. The "learning" of the SMA 10 is done by storing the last sensor signal output values for λ and A/M (or MAP) that produced the desired sensor signal input values from the λ and A/M (or MAP) sensors, against the specific RPM and MAP/TP values. Different λ and A/M (or MAP) sensor signal output values are thus stored for different values of RPM and MAP/TP. If one of the digital output terminals 14.6 or 14.8 (see Figure 1 ) of the SMA 10 is connected to a fuel injector, and the desired signal values can not be obtained by means of the modification of the sensor signals to the ECU, the fuel injector can be triggered to supply an increased amount of fuel to the engine until the desired signal values have been achieved.

It is to be appreciated that in this example, only one feedback control algorithm 48 is shown, but other feedback control algorithms similar to reference numeral 48 can be provided to control other engine parameters.

It is further to be appreciated that, where necessary, the two- dimensional array 42 shown in Figures 2 and 3 can be simplified by using only one value from input terminal 12 thus forming a one-dimensional array.

Where ECU'S of engines are typically controlling the engine to optimise exhaust gas emissions, the invention can provide a method of varying the ECU output to modify engine performance and/or fuel consumption by adjusting ignition timing and/or fuel injection of the engine thereby to modify performance and/or fuel consumption of the engine. This can be achieved by use of output terminals 14.6, 14.8 and 14.10.

The invention, as illustrated, provides a new method of modifying an output signal of an engine control unit and provides a new signal modification accessory for use in combination with an engine control unit and whereby the accessory can be readily fitted as an accessory to an ECU. The accessory can be fitted in series with the ECU as shown, but may also be fitted in parallel with the ECU.

Claims

CLAIMS:

1. A method of modifying an output signal of an electronic engine control unit controllably connected to an internal combustion engine, which method includes receiving at least one sensor signal, representative of an engine performance parameter, from at least one sensor; modifying the sensor signal by means of a control algorithm; and sending to an input of the engine control unit the modified sensor signal, thereby to vary the engine control unit output signal and thus to modify the performance of the engine, via the engine control unit.

2. A method as claimed in claim 1 , in which the received sensor signal originates from at least one of the following sensors: an air mass sensor, a manifold ambient pressure sensor, a throttle position sensor, a lambda sensor, a revolutions per minute counter, a crankshaft position sensor, an exhaust gas temperature sensor, and an engine temperature sensor.

3. A method as claimed in claim 2, in which the sensor signal is modified by means of an' open loop control algorithm which generates a simulated sensor output signal in response to at least one sensor signal received.

4. A method as claimed in claim 2, in which the sensor signal is modified by means of a closed loop control algorithm which generates a simulated sensor output signal to obtain a desired sensor input signal.

5. A method as claimed in claim 3 or claim 4, in which a set of simulated sensor output signal values is mapped in a single-dimensional array to a set of sensor signal values, to serve as an input to the control algorithm.

6. A method as claimed in claim 3 or claim 4, in which at least one set of simulated sensor output signal values is mapped in a multi-dimensional array to at least two sets of sensor signal values, to serve as an input to the control algorithm.

7. A method as claimed in claim 4, in which the desired sensor input signal originates from one sensor and in which the sensor signal that is modified originates from another sensor.

8. A method as claimed in claim 7, in which the desired sensor input signal originates from an exhaust gas temperature sensor and in which the sensor signal that is modified originates from a lambda sensor.

9. A method of modifying the performance of an internal combustion engine during operation, which method includes measuring the temperature of exhaust gas from the internal combustion engine; and adjusting an air/fuel ratio supplied to the internal combustion engine to obtain a desired exhaust gas temperature.

10. A signal modification accessory connectable between at least one engine sensor and an engine control unit controllably connected to an internal combustion engine, the signal modification accessory including a signal modification accessory input terminal connectable to the engine sensor; a signal modification accessory output terminal connectable to at least one input terminal of the engine control unit; and a processor intermediate the signal modification accessory input terminal and the signal modification accessory output terminal, the processor being operable to generate a modified signal at the signal modification accessory output terminal in accordance with a value of a signal received at the signal modification accessory input terminal.

11. A signal modification accessory as claimed in claim 10, in which the engine sensor is selected from at least one of the following sensors: an air mass sensor, a manifold ambient pressure sensor, a throttle position sensor, a lambda sensor, a revolutions per minute counter, a crankshaft position sensor, an exhaust gas temperature sensor, and an engine temperature sensor.

12. A signal modification accessory as claimed in claim 11 , in which the processor is programmed with an open loop control algorithm, operable, when executed, to generate a modified sensor output signal at the signal modification accessory output terminal in accordance with a value of each particular sensor input signal received at the signal modification accessory input terminal.

13. A signal modification accessory as claimed in claim 11 , in which the processor is programmed with a closed loop control algorithm, operable, when executed, to generate a modified sensor output signal at the signal modification accessory output terminal to obtain a desired sensor input signal value at the input terminal.

14. A signal modification accessory as claimed in claim 12 or claim 13, in which the processor includes storage means operable to store a set of simulated sensor output signal values, mapped in a single-dimensional array to a set of sensor input signal values, to serve as an input to the control algorithm.

15. A signal modification accessory as claimed in claim 12 or claim 13, in which the processor includes storage means operable to store al least one set of simulated sensor output signal values, mapped in a multi- dimensional array to at least two sets of sensor input signal values, to serve as an input to the control algorithm.

16. An engine control installation, which includes at least one sensor for measuring at least one engine parameter; a signal modification accessory having a signal input terminal connected to the sensor, thereby to receive a signal from the sensor, and, in response, to generate a modified sensor signal at a signal output terminal; and an engine control unit having an input terminal connected to the signal output terminal of the signal modification accessory for receiving the modified sensor signal and having at least one output terminal controllably connected to an engine, for controlling the operation of the engine.

17. A method as claimed in claim 1 or claim 9 substantially as described and as illustrated herein.

18. A signal modification accessory as claimed in claim 10, substantially as described and as illustrated herein.

19. An engine control installation as claimed in claim 16, substantially as described and as illustrated herein.