WO2000029733A1

WO2000029733A1 - Fuel boost compensator controller

Info

Publication number: WO2000029733A1
Application number: PCT/ZA1999/000121
Authority: WO
Inventors: Heinrich François LATEGAN; Stephen John Fischer
Original assignee: Lategan, Hendrik, Adriaan
Priority date: 1998-11-13
Filing date: 1999-11-12
Publication date: 2000-05-25
Also published as: AU1480200A

Abstract

The invention provides an accessory (20) for an internal combustion engine (10) including sensing means (22, 24) for sensing the temperature of the exhaust gas of an engine (10); a valve arrangement (16) connected selectively to regulate air pressure exerted on a boost compensator (18) operable to control fuel fed into the combustion chamber and control means (26) connected to and responsive to the sensing means (22, 24) and adapted to control the valve arrangement (16) in response to a compensation factor associated with a particular temperature. Furthermore the invention provides a method for controlling fuel fed into the intake of an internal combustion engine (10). The method including sensing the temperature of the exhaust gas of the engine an regulating the air pressure exerted on a boost compensator (18) thereby to control a portion of the fuel fed into the fuel intake.

Description

FUEL BOOST COMPENSATOR CONTROLLER

TECHNICAL FIELD

This invention relates to internal combustion engines. In particular, it relates to an accessory for internal combustion engines that controls the quantum of fuel fed into the combustion chamber by controlling a boost compensator or boost sensor in response to the temperature of the engine.

BACKGROUND ART A conventional internal combustion engine, especially a forced diesel induction engine, may include a boost compensator for controlling the quantum of fuel fed into its combustion chamber in relation to the pressure inside the combustion chamber. In response to an increase or decrease in the pressure inside the combustion chamber, the boost compensator increases or decreases, respectively, the quantum of fuel fed into the combustion chamber. For the purposes of this specification the term boost compensator should be interpreted broadly to include boost sensors and any device operable to control the quantum of fuel fed into the combustion chamber in response to pressure exerted on it.

Accessories to internal combustion engines that regulate the quantum of fuel injected into the combustion chamber in order to optimise fuel consumption and improve exhaust purification are well known in the field. US 5, 564,404 discloses an invention in which an air/fuel ratio control device is provided for feeding the engine with a mixture of a desired lean air/fuel ratio for a given time from the time on which the engine is started. Both the temperature of the exhaust gas and that of the coolant are measured to infer the engine temperature, which determines the time for which the air/fuel ratio is to be regulated. US4,020,814 discloses an invention that also measures exhaust gas temperature to infer the temperature of the engine and subsequently compares the sensed temperature with a preselected reference which corresponds to a maximum safe operating temperature. In the case that the sensed temperature exceeds the preselected value, a valve in the fuel supply system is sized to vary the fuel flow rate to the engine, decreasing the fuel intake. OBJECTIVES OF THE INVENTION

An objective of the invention is to provide a means of protecting an internal combustion engine from over-temperature by controlling the quantum of fuel fed into the combustion chamber in relation to the surrounding engine conditions, specifically the temperature of the engine.

DISCLOSURE OF INVENTION

Accordingly, the invention provides an accessory for an internal combustion engine comprising sensing means for sensing the temperature of the exhaust gas of an engine; a valve arrangement adapted to regulate air pressure exerted on a boost compensator which is responsive to such pressure and which operates to control fuel fed into the combustion chamber; and control means connected to the sensing means and adapted to control the valve arrangement in response to a compensation factor associated with a particular engine temperature.

The valve arrangement is typically a binary or flip-flop valve having a single inlet port and two outlet ports, for example a DENSO - 9091012157. The inlet port may be connected to an outlet port of an engine manifold which is normally connected to the boost compensator in prior art engines, and one of the outlet ports may be connected to a boost compensator. The second outlet port may define a vent for venting gas thereby to regulate the pressure exerted on the boost compensator. Accordingly, the valve arrangement is typically connected intermediate the conventional outlet port of the engine and the conventional boost compensator.

The control means may include storage means with a compensation profile stored therein. The compensation profile typically provides at least one compensation factor as a function of temperature.

The control means may be operable to control the opening and closing of the valve arrangement dependent on the compensation profile. For example, the compensation profile may include ten fixed compensation factors corresponding to a sensed engine temperature, and accordingly, the control means may control the opening and closing of the valve arrangement in response to the compensation factor associated with a particular temperature.

The control means may be operable to provide and transmit a pulsed output signal to the valve arrangement, the frequency and duty cycle of the signal being dependant upon the sensed temperature. Typically, the output cycle is a pulse width modulated signal which is characterised by the compensation profile.

The temperature sensing means may be provided by a probe positioned at the engine outlet, which measures the exhaust gas temperature and transmits this measurement to the control means via an electronic signal.

The storage means may intermittently store or log vehicle operating parameters for subsequent analysis. Typically, the control means stores the temperature sensed at the exhaust of the combustion chamber at predetermined time intervals.

The accessory may include an RS-323 serial interface or the like. Accordingly, the control means is typically a microprocessor based controller which may be programmed via the serial interface. The compensation profile may be stored in the storage means via the serial interface. Further, the vehicle operating parameters may be downloaded from the accessory via the serial interface.

The accessory may include a power supply or voltage regulator for powering its electrical circuitry. Typically a voltage regulator is connected to a conventional electrical supply line of the vehicle. Preferably, the accessory includes polarity protection means for protecting the accessory in the event of it being connected to the conventional electrical system with incorrect polarity. Also included within the scope of the invention, a fuel regulating system for an internal combustion engine is provided which includes a boost compensator; and an accessory as described above.

The accessory is typically, but not exclusively, fitted to a conventional turbo-charged diesel engine, a super-charged engine, or the like.

Also included within the scope of the invention, a method is provided for controlling fuel fed into an internal combustion engine including the steps of sensing the temperature of the exhaust gas of the engine and regulating air pressure exerted on a boost compensator which is responsive to such pressure, thereby to control the quantum of fuel fed into the fuel intake.

BRIEF DESCRIPTION OF DRAWINGS The invention is now described by way of example only, with reference to the accompanying diagrams

Figure 1 : shows a schematic diagram of part of a diesel engine in accordance with the invention;

Figure 2: shows a schematic circuit diagram of a power supply providing voltage for the electronics of the controller via a voltage regulator in connection with the conventional electrical system of the vehicle; and

Figure 3: shows a schematic circuit diagram of a diesel engine accessory, also in accordance with the invention, of the diesel engine of Figure 1.

BEST MODES FOR CARRYING OUT THE INVENTION

Referring to the drawings, reference numeral 10 generally indicates part of an internal combustion engine in accordance with the invention. The engine 10 includes an intake manifold 12 connected via a conduit 14 and a valve arrangement 16 to a conventional boost compensator 18. The valve arrangement 16 forms part of a diesel engine accessory 20, also in accordance with the invention, which further includes temperature sensors 22, 24, control means in the form of a microprocessor controller 26, and a visual warning indicator in the form of an LED 28. In use, the engine accessory 20 is operable to control the quantum of fuel fed to a fuel intake of the engine 10 indirectly via the boost compensator 18, as described in more detail below.

Referring in particular to Figure 2 of the drawings, the controller 26 includes a power supply 30 which provides a 5 V regulated output voltage to various components of the controller 26 via its output terminal 32. The power supply 30 includes a conventional voltage regulator 34 (e.g. an LM 2931 AT50) which is connected via a resistor 36 and a diode 38 to a positive terminal 40 of an electrical system of the engine 10. A negative terminal 42 is connected to an earth of the controller 26 and to a negative supply of the engine 10. A 12 V output is provided at terminal 44 which is connected via diodes 46, 48 to the positive terminal 40. The power supply 30 further includes conventional circuitry 50 which is normally associated with the voltage regulator 34 for normal operation thereof.

The controller 26 further includes an RS-232 interface chip 52 (e.g. a MAX 232 level converter) connected via lines 54 to a microcontroller 56 (e.g. an ATMEL at 89C2051). The microcontroller 56 is, in turn, connected via lines 58 to a processor re-booting chip 60 (e.g. a MAX 813L) which monitors operation of the microcontroller 56 and selectively re-boots the microcontroller 56 in the event of it hanging. The microcontroller 56 is connected via lines 62 to storage means in the form of an EEPROM 64 (e.g. a 24LC02) which stores compensation profile details (See table 1) and data which is logged during operation of the accessory 20, as described in more detail below. The interface chip 52 is connected via lines 66 to a connector 68 which may be selectively connected to a personal computer or the like for programming the controller 56 or retrieving data stored in the EEPROM 64 in use. The interface chip 52 and the microcontroller 56 include oscillator circuitry 70, 72 respectively to enable them to function in a conventional fashion. The temperature sensor 24 (see Figures 1 and 2) is connected to terminals 74 (see figure 2) and associated circuitry 76 and via lines 78 to ports of the microcontroller 56. The temperature sensor 24 is a conventional DS 1820 temperature sensing chip which is typically operable to provide an accuracy of about 1°C over a range of 0°C to 125°C in a digital output format. In a similar fashion, the temperature sensor 22 is connected to the microcontroller 56. The temperature sensors 22, 24 are typically operable to sense gas temperature in an exhaust manifold (not shown) of the engine 10.

The controller 26 further includes switching circuitry 82 defined by transistors 84, 86 and their associated circuitry. The transistor 84 is connected via line 88 to an output port of the microcontroller 56 and the transistor 86 is connected via terminals 90 to the valve arrangement 16 thereby to allow the microcontroller to control opening and closing of the valve arrangement 16.

The LED 28 (see Figure 1) is connected via terminals 92 (see figure 2) to a switching transistor 94. The switching transistor 94 is connected via line 96 to an output port of the microcontroller 56. In use, if the temperature of the engine 10 rises above a predetermined value, the controller 56 switches the transistor 94 on thereby to illuminate the LED 28.

In a conventional internal combustion engine, pressure from an intake manifold is transferred to a boost compensator. When the pressure in the intake manifold increases, the boost compensator then enhances the quantum of diesel fuel fed into the fuel intake of the engine 10 i.e. it increases the richness of the air/diesel mixture in the fuel intake. However, a richer mixture produces increased heat and, in certain circumstances, the increased temperature may rise to such a level so as to cause damage to the diesel engine.

However, in the diesel engine 10 which is fitted with the engine accessory 20, the accessory 20 monitors engine temperature via its sensors 22, 24 and reduces the pressure sourced from the intake manifold which is applied to the boost compensator 18 thereby compensating for increased engine temperature. In particular, the controller 22 via its sensors 22, 24 intermittently (typically at a rate of about 2 Hz) senses the temperature in the exhaust path of the gases from the combustion chamber and accesses the following compensation profile table which is stored in the EEPROM 64.

COMPENSATION PROFILE

TABLE 1

The microcontroller 56 then retrieves a frequency value (column 3) and a duty cycle value (column 4) and a control output is generated along line 88 to the switching circuitry 82 which controls operation of the valve arrangement 16. The valve 16 is typically a DENSO - 90910-12157 which has a control mechanism which reciprocates between its output ports 16.1 and 16.2 (see figure 1). Thus, a pulse width modulated waveform, of a particular frequency and duty cycle which is sourced from the compensation profile table, is transmitted valve controller to the effect the pressure sourced from the intake manifold 12 and applied to the boost compensator 18. As shown in Table 1, the duty cycle may be varied depending upon the temperature sensed in the intake manifold 12. As a result of a reduced pressure being transmitted to the boost compensator 18, the quantum of fuel fed into the fuel intake of the engine 10 is decreased. This results in a reduction of power from the engine 10 as shown by the power loss/boost reduction column (column 5) in Table 1 for a particular engine tested. If the temperature sensed in the intake manifold drops below 100°C, the microcontroller 56 is configured to activate the valve arrangement 16 so that all of the pressure sourced from the intake manifold 12 via the conduit 14 is directed to the boost compensator 18. If the temperature rises above 104°C, 5% of the pressure is fed to the boost compensator 18 and 95% is dissipated via the outlet port 16.2.

It is however to be appreciated that a variety of different frequencies and duty cycles may be programmed into the EEPROM 64 via the RS-232 interface chip 52. Thus, the compensation profile may be customised for each particular internal combustion engine to which the accessory 20 is fitted. When performing maintenance on a vehicle including the engine 10, operating temperatures stored or logged in the EEPROM 64 may be downloaded onto a personal computer via the interface chip 52 for analysis. The personal computer when connected to the accessory 20 may be programmed to show, in real time, the temperature sensed, the operative frequency and duty cycle of the waveform transmitted by the controller, the compensation profile table, or the like.

The inventors believe that the invention, as illustrated, provides an effective method of controlling fuel fed into the diesel engine 10. As the quantum of fuel fed into the diesel engine 10 by the boost compensator 18 is reduced when predetermined temperatures are reached, the heat generated in the engine 10 may be reduced to inhibit the engine 10 from operating under unfavourable operating conditions.

Claims

1. An accessory for an internal combustion engine comprising sensing means for sensing the temperature of the exhaust gas of an engine; a valve arrangement adapted to regulate air pressure exerted on a boost compensator which is responsive to such pressure and which operates to control a portion of the fuel fed into the combustion chamber; and control means connected to the sensing means and adapted to control the valve arrangement in response to a compensation factor associated with a particular engine temperature.

2. An accessory as claimed in claim 1 wherein the valve arrangement is a binary or flip- flop valve having a single inlet port and two outlet ports, the inlet port being connected to an outlet port of an engine manifold, one of the outlet ports being connected to a boost compensator and the second outlet port defining a vent for venting gas, thereby to regulate the pressure exerted on the boost compensator.

3. An accessory as claimed in claim 1 wherein the control means includes storage means with a compensation profile, providing at least one compensation factor as a function of temperature, stored therein.

4. An accessory as claimed in claim 3 wherein the control means is operable to control the opening and closing of the valve arrangement, such opening and closing of the valve arrangement being dependent on the compensation profile.

5. An accessory as claimed in claim 3 wherein the control means transmits a pulse width modulated output signal characterised by the compensation profile, to the valve arrangement.

6. An accessory as claimed in claim 1 wherein the sensing means for sensing the temperature of the engine comprises a probe positioned at the engine outlet, which measures the exhaust gas temperature and transmits this measurement to the control means via an electronic signal.

7. An accessory as claimed in claim 1 or 6 wherein the control means is operable to provide and transmit a pulsed output signal to the valve arrangement, the frequency and duty cycle of the signal being dependent upon the sensed temperature.

8. An accessory as claimed in claim 3 wherein the storage means intermittently stores vehicle operating parameters for subsequent analysis.

9. An accessory as claimed in claim 1 wherein the control means is a programmable microprocessor based controller.

10. An accessory as claimed in claim 9 wherein a serial interface is provided which enables the control means to be programmed, the compensation profile to be stored in the control means and the vehicle operating parameters to be downloaded from the control means.

11. An accessory as claimed in claim 1 wherein a power supply or voltage regulator is provided for powering its electrical circuitry in conjunction with conventional electrical supply line of the vehicle.

12. An accessory as claimed in claim 11 wherein polarity protection means is provided for protecting the accessory in the event of it being connected to the conventional electrical system with incorrect polarity.

13. A fuel regulating system for an internal combustion engine comprising a boost compensator and an accessory as claimed in any one of the preceding claims.

14. A method of controlling the fuel operatively fed into an internal combustion engine, the method including the steps of sensing the temperature of the exhaust gas of the engine and regulating air pressure exerted on a boost compensator which is responsive to such pressure thereby to control a portion of the fuel fed into the fuel intake.

15. A method as claimed in claim 14 wherein the step of regulating the air pressure exerted on a boost compensator includes connecting the inlet port of a valve arrangement to an outlet port of an engine manifold; connecting one of the outlets to a boost compensator; and providing a second outlet port as a vent for venting gas, thereby to rgulate the pressure exerted on the boost compensator.

16. A method as claimed in claim 14 wherein the step sensing the temperature of the engine is provided by positioning a probe at the engine outlet thereby measuring the exhaust gas temperature and transmitting this measurement to the control means via an electronic signal.

17. A method as claimed in claim 14 wherein the step of regulating the air pressure exerted on a boost compensator includes storing a compensation profile on control means, the compensation profile providing at least one compensation factor as a function of temperature.

18. A method as claimed in claim 17 wherein the step of regulating the air pressure exerted on a boost compensator includes the opening and closing of a valve arrangement, such opening and closing of the valve arrangement being dependent on the compensation profile.

19. A method as claimed in claim 14 or 15 wherein the step of regulating the air pressure exerted on a boost compensator includes connecting the inlet port of a valve arrangement to an outlet port of an engine manifold; connecting one of the outlets to a boost compensator; and providing a second outlet port as a vent for venting gas, thereby to regulate the pressure exerted on the boost compensator.

20. A method as claimed in claim 17 wherein the step of regulating the air pressure exerted on a boost compensator includes transmitting a pulse width modulated output signal characterised by the compensation profile, to the valve arrangement.

21. A method as claimed in claims 14 wherein the step of regulating the air pressure exerted on a boost compensator includes storing, intermittently, vehicle operating parameters for subsequent analysis.

22. A method as claimed in claim 14 wherein the step of regulating the air pressure exerted on a boost compensator includes programming a programmable microprocessor-based control means.

23. A method as claimed in claim 22 wherein the step of regulating the air pressure exerted on a boost compensator includes providing a serial interface enabling the control means to be programmed, the compensation profile to be stored in the control means and the vehicle operating parameters to be downloaded from the control means.

24. A method as claimed in claim 14 wherein the step of regulating the air pressure exerted on a boost compensator includes powering the electrical circuitry with a power supply or voltage regulator in conjunction with a conventional electrical supply line of the vehicle.