WO2005038227A2

WO2005038227A2 - Engine management system

Info

Publication number: WO2005038227A2
Application number: PCT/AU2004/001439
Authority: WO
Inventors: Mike Thompson
Original assignee: Mike Thompson
Priority date: 2003-10-20
Filing date: 2004-10-20
Publication date: 2005-04-28
Also published as: WO2005038227A3

Abstract

A management system for use in compression ignition engines (50) wherein the management system comprises the steps of: measuring engine demand of the engine; and regulating the flow of a gas phase fuel injected into the air intake (42) of the compression ignition engine in response to the measured engine demand.

Description

A MANAGEMENT SYSTEM FIELD The present invention relates to a performance improvement system for compression engines and in particular for use in diesel engines.

BACKGROUND Diesel provides an efficient fuel source for generating power, in particular in powering motor vehicles. Typical diesel engine efficiencies are in the order of 75% with compression ratios ranging from 14:1 to 25:1 being attainable. This makes diesel engines more attractive that petrol engines which run at efficiencies in the order of 50% and having compression ratios of between 8:1 and 12:1. Thus, in effect, almost double the power can be attained from the same amount of diesel fuel as petrol fuel. While diesel engines are still not as efficient as kerosene engines which can attain thermal efficiencies of up to 95%, diesel fuel is less volatile than kerosene, therefore making it a safer fuel to contain, especially when stored on motor vehicles. Typically, in a diesel engine, air will be drawn through an air valve into a combustion chamber where it is compressed to a desired pressure, then diesel fuel is sprayed into the combustion chamber by spray injectors in droplet form, at which point the diesel fuel is ignited due to increased pressure, causing it to reach its flash point and combusting the diesel fuel within the combustion chamber. The combustion reaction drives the piston to turn a crankshaft thereby providing mechanical power, for instance for propelling a motor vehicle. After combustion of the fuel, an exhaust valve will open to release the combustion products from the combustion chamber into the exhaust manifold. These exhaust or waste products include reaction products from the combustion reaction as well as excess air and unspent fuel. It will be appreciated that any excess air or unspent fuel will be heated by the combustion reaction and released to the exhaust thereby decreasing the efficiency of the engine. The exhaust products may be removed through the exhaust, but commonly are redirected to drive, for instance a turbo charger, where the exhaust air drives a compressor to provide air at increased density to the combustion chamber to enhance the combustion reaction efficiency. In this way the provision of additional air drives the reaction equilibrium to consume more fuel to react during combustion, thereby increasing the amount of fuel burnt and the reducing the fuel in the waste products. The thermal efficiency of the fuel is dependant on the percentage of fuel burnt during combustion. This is a limit peculiar to each fuel, with diesel typically limited to 75% thermal efficiency due to the slow speed at which it burns in relation to the timing of the combustion cycle. The thermal efficiency can be improved by the addition of more combustible fuels to the diesel fuel. A problem with combining such fuels, is the low flash point of the diesel causes it to ignite readily when in contact with the second fuel making the combustion difficult to control. Previous attempts have been made to combine Liquid Petroleum Gas with diesel with limited success. It has been attempted to control the addition of Liquid Petroleum Gas using a metering valve connected to throttle position, but this method has proved cumbersome and inefficient and has not been widely adopted. We have found a way to improve the performance of compression engines ameliorating or at least providing a useful commercial alternative to the aforementioned problems.

SUMMARY OF THE INVENTION According to a first broad form of the invention, there is provided a management system for use in compression engines wherein the management system comprises the steps of: measuring engine demand of a compression engine; and regulating flow of a gas phase fuel injected into the air intake of said compression engine in response to the measured engine demand. In a second broad form of the invention there is provided a gas phase fuel supply for a compression engine wherein the supply comprises a tank, a regulator, an engine demand sensor and an injector, said injector being adapted to spray a gas phase fuel into an air intake of a compression engine, wherein the demand sensor is controllingly connected to the regulator whereby a regulated supply of gas phase fuel is supplied to the injector from the tank. In a third broad form there is provided a compression engine comprising: a combustion chamber for receiving and combusting fuel; at least one fuel inlet into the combustion chamber; at least one air intake valve to allow air into the combustion chamber; an exhaust valve to allow combustion products to exhaust from the combustion chamber; and at least one injector to spray a gas phase fuel into the air intake before said air enters the combustion chamber wherein the gas phase fuel is regulated in response to engine demand. We have found that by measuring engine demand and using the engine demand to regulate gas phase fuel flow, we obtain improved fuel efficiency and engine performance. The engine demand may be measured by using a sensor to measure manifold absolute pressure (MAP) and thereby the condition of the engine. This allows for the actual engine demand to determine the amount of gas phase fuel to be mixed with air so that the amount can be increased when the engine is under an increased load. We have found that this is a better indicator than a throttle position sensor which only indicates when the accelerator is being used by a driver. The manifold absolute pressure (MAP) is measured by a pressure sensor, preferably an electronic transducer being placed in the manifold to record the pressure inside the engine inlet manifold. The absolute pressure is the difference between the barometric or atmospheric pressure and the vacuum created by the pistons inside the manifold. The transducer includes a flexible component such as a strain gauge, flexible plate or diaphragm which is displaced by the pressure, the displacement being proportional to the pressure at the gauge. MAP sensors generally have a three wire circuit. The first wire being a 0 - 5 volt reference, the second a ground and the third wire being the output. Thus the displacement is recorded by transducer and sent as output to the controller. At idle, the MAP sensor will give a floating value/ voltage, depending on atmospheric pressure. The gas lock will remain closed at idle, as there should be no engine demand. The 12v signal is converted to 255 step values with maximum 12v reached at 255. The MAP sensor gas lock (on) is set at step 64 so that when the MAP sensor input reaches this level, the gas lock at the regulator is engaged, while MAP sensor gas lock (off) is set at step 62 to allow a slight lag. The floating value for MAP is set at step 57. An upper limit may be set any where from 0 to 255. Preferably the upper limit is set at step 130, being approximately the value for full throttle. The regulator may be a first stage regulator or a phase converter capable of delivering variable amounts of gas phase fuel to be mixed with the air. The amount of gas phase fuel supplied is in response to the engine demand as reported to the controller by the pressure gauge or sensor. The regulator allows gas to flow into a first stage, with pressure building as more gas is introduced, this applies force to a diaphram which activates a valve to release gas on demand. The phase conversion occurs as the pressure of the liquid is increased and heat is applied by heat exchange from a coolant operating at radiator temperature passed through the regulator. The gas phase fuel supply may be blocked by using a lock in concert with the regulator to inhibit the flow of gas phase fuel therefrom. Preferably a negative converter is used with the high pressure side being down stream to draw the liquid into the regulator. However a positive flow regulator could be used, if adapted with suitable safety measures to stop back flow. The controller may be a microprocessor incorporating, for example, a Modbus ASCII slave driver. Typically a direct digital control microprocessor will be used having typically 64 points, 16 points each for digital input, digital output, analog input and analog output. Using this type of controller, up to 32 sensing devices can be used measuring up to 16 analog or 16 digital activities. Thus the controller can monitor events (digital inputs) such as a maintenance switch being on or off, or variables (analog inputs) including the MAP or temperature readings. Similarly the controller may effect an event such as turning a device off (digital output), or send a variable instruction (analog output) such as the amount of gas phase fuel to be supplied to the air intake. The controller may be programmed to block supply of the gas phase fuel when predetermined conditions are met, such as one of the sensors stops working (thus no signal is received by the controller) to ensure safety of the system. The controller may include a lambda setting so that the condition of the engine and the other measured parameters are continually monitored and compensated for to provide optimal operating conditions within the engine. The controller may be programmed to shut off fuel supply when predetermined parameters are met. This may include for instance the activation of a switch for maintenance, so that the gas lock may be locked inhibiting gas phase fuel flow outside of the tank and any remaining gas phase fuel in the lines may be used up before maintenance is started on the engine. This is important for safety during maintenance, as the gas phase fuel has a low flash point and may be easily ignited when the engine is under repair. This problem is alleviated by containing the gas phase fuel within the tank. It will be appreciated that during storage in the tank, the gas phase fuel is stored under pressure and may be in liquid form. The controller may be controllable remotely by use of modem and wireless technology. The system may include a temperature sensor on the exhaust manifold. By measuring the exhaust air, the controller may add sufficient gas phase fuel to compensate for the changes in air density within the combustion chamber. The supply of gas phase fuel may be cut off for high exhaust temperature readings. The controller may control a heater fitted in the exhaust system prior to a catalytic converter. The controller engages the heater in response to a low temperature reading measured relative to a set point. The controller disengages the heater in response to a high temperature reading measured relative to a set point. This is especially useful for cool climates where coolant can drop below the operating temperature of the catalytic converter. The system may include a oxygen sensor on the exhaust so that the gas phase fuel level may be adjusted to reduce excess air and unspent fuel, such as diesel, which represents inefficient fuel consumption. The system may include a water temperature sensor in the cooling system to monitor engine coolant temperatures. The controller may lock the gas in response to the coolant temperature falling below a set point. This prevents the phase converter freezing due to low temperatures which may cause damage to the engine or phase converter. When the engine operating temperature is obtained the controller may unlock the gas lock at the converter to allow the gas phase fuel to mix with the air. The controller may engage a stepper motor in response to the measured engine demand. The stepper motor may be used to control the regulator, allowing a linear increase in the amount of fuel supplied from the regulator to the air intake for mixing. The controller may respond to an alternator signal so that the system shuts off when there is no charge and recalibrates when it receives a signal from the controlled that the alternator is on. Typically, the controller will require a 12v signal to disengage the gas lock. The controller may monitor the oil pressure using an oil pressure sensor to ensure the engine is operating at safe levels. The controller may measure when the engine brake is applied so that the gas phase fuel supply may be blocked to reduce the engine power. Similarly the presence of foot brake may be measured so that gas phase fuel supply may be reduced. The gas phase fuel may be stored in liquid form in a storage tank and introduced into the air intake in a desired amount by a regulator. The tank may include a gas lock to restrict the flow of liquid from the tank into the liquid line. The tank may include a fuel meter to measure the amount of fuel left in the tank for refilling purposes. The fuel injectors are located in the air intake to allow the gas fuel to be mixed with air before entering the combustion chamber. Typically the injector sprays a jet of gas phase fuel into the air, which is then drawn into the combustion chamber. The engine may be a typical diesel engine having a cylinder block containing a plurality of cylinders driven by associated pistons, within cylinder bores.

The base of the pistons are attached to a crankshaft located below the cylinder block.

Within each bore are three ports, one being an air inlet, another being an exhaust outlet and the third being the fuel inlet for the diesel. Typically the flow of fluid through the air inlet and exhaust outlet are controlled by inlet and exhaust valves respectively. A combustion chamber is provided at the top of the cylinder bore between the valves and the cylinder. The diesel fuel is sprayed into the combustion chamber by an injector at the fuel inlet. The timing of the piston is such that the inlet valve is opened and air is drawn into the bore during the upstroke of the piston. The air (mixed with gas phase fuel) is compressed as the piston continues its upstroke.

Just before the top of the stroke is reached, the diesel is injected causing the fuels to combust. The combustion reaction drives the piston down, in turn driving the crankshaft. The exhaust valve opens and exhaust is expelled during the upstroke, then closed to allow the air valve to open. A person skilled in the art would appreciate that other compression engines could be substituted for a diesel engine. The system may include a turbo charger to further improve efficiency of the fuel. The exhaust gases leaving the engine may be expanded through a turbine and used to drive a compressor on a turbo charger. The compressor raises the density of the air drawn into the combustion chamber which means more reactants are present for the combustion reaction thereby generating more or boosted power. The pyro temperature of the exhaust air in the turbo charger may be monitored to ensure the manufactures specifications are not exceeded, and if necessary the amount of gas phase fuel may be reduced. The system may include an emulator to mimic the manifold absolute pressure readings at a scaled factor so that the (ECU) is governed to limit the gas phase fuel supplied to thereby reduce horsepower output. The system may include a display unit eatable in the cab of a vehicle or external to a motor. The display unit may be wired to an existing instrument panel, for instance in the cab of a truck. The driver may view all of the measured parameters from the display panel, especially the level of fuel remaining in the tank. The display unit may be in the form of a road relay. A preferred embodiment of the invention will now be described by way of example only, in reference to the drawings.

BRIEF DESCRIPTION OF DRAWINGS FIG 1 shows a schematic view of the performance improvement system according to an embodiment of the invention; FIG 2 shows a wiring diagram of the performance improvement system according to an embodiment of the invention; FIG 3 shows a wiring diagram of the performance improvement system according to an embodiment of the invention; FIG 4 shows a wiring diagram of the display device of the performance improvement system according to an embodiment of the invention; and FIG 5 shows a wiring diagram of the display device of the performance improvement system according to an embodiment of the invention; and FIG 6 shows the digital and analog inputs and outputs of the controller according to the embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG 1 shows a schematic view of the performance improvement system comprising an engine 50 having a combustion chamber an inlet manifold 46 for drawing air into the combustion chamber, an exhaust manifold 60 for exhausting combustion products and an air intake 42 where a gas phase fuel is added to the air prior to combustion. The gas phase fuel is contained in a tank 10 in liquid form for storage before passing through a phase converter 20 to form a gas to be mixed with the intake air. The phase converter 20 is controlled by a logic unit (not shown) to regulate the amount of gas phase fuel supplied to the air intake 42. The logic unit regulates the gas phase fuel supplied according to the engine demand as measured by a manifold absolute pressure (MAP) sensor 30. In this way the amount of primary fuel, for example diesel, consumed is optimised. Supply from the gas tank can be blocked using a gas lock 11. When allowed to flow, the pressure of gas phase fuel in a line 13 can be measured by a sensor 12. The gas phase fuel may then enter a phase converter or first stage regulator to be sprayed into the air intake through injectors 40. The fuel/air mix may then be drawn into the combustion chamber. Further sensors can be used to measure air temperature 41 at the air intake, so that adjustments can be made to the gas phase fuel supplied. Oxygen levels in the exhaust 63 may be measured to reduce wastage. Air temperatures in the exhaust 64 may also be measured to maximise the combustion reaction. In FIG 2 the wiring diagram of the performance improvement system shows the flow of gas phase fuel from the tank 10 may be inhibited by the gas lock 11 which is controlled by the controller. Thus the controller may be programmed to cut off supply of the gas phase fuel from the gas tank 10 to the air intake. This allows for a maintenance or safety program to run containing the gas phase fuel within the tank 10 as constrained by the running program. Additionally the controller may measure the gas phase fuel level within the tank, displayable for use of a driver. The phase converter 20 or regulator includes another gas lock 11 so that the flow of gas phase fuel into the air intake may be inhibited or regulated by the controller to supply a desired amount of gas phase fuel to the air intake in response to the conditions of the engine, including engine demand. The manifold absolute pressure (MAP) is measured by a MAP sensor which signals the controller, indicating the condition of the engine. The controller may control a stepper motor 90 located between the regulator and gas phase fuel to adjust the amount of gas phase fuel delivered. The stepper motor 90 allows for the amount to be adjusted linearly as determined by engine demand. The controller may respond to a signal from an alternator so that the gas lock on the gas phase fuel is locked to inhibit the supply of gas phase fuel when the alternator is inactive. FIG 3 shows the controller with sensors on the exhaust gas temperature using a pyro sensor 110 located in the exhaust pipe. The pyro sensor 110 is particularly useful where the exhaust gases are run through the system for example through an air purifier and back into the air intake. In this particular instance, the exhaust air raises the temperature of the air drawn into the combustion chamber affecting the engine demand and gas phase fuel required by changing the density of mixed gas phase fuel and air. Thus the supply of gas phase fuel can be increased or decreased in response to this signal. Similarly the exhaust brake can be measured 120 as well as the foot brake (not shown). When the controller receives these signals, the gas lock on the regulator 21 can shut off the supply of gas phase fuel to the air intake. FIGS 4 and 5 show the wiring diagram for installing a display unit on the existing instrument panel of a motor vehicle. FIG 6 shows digital and analogue inputs and outputs for a controller, including the parameters to be measured and controlled. A person skilled in the art would understand that other parameters may be used to optimally control the system. Whilst the above has been given by way of illustrative example of the invention, many modifications and variations may be made thereto by persons skilled in the art without departing from the broad scope and ambit of the invention as herein set forth. The term "comprise", or variations of the term such as "comprises" or "comprising", are used herein to denote the inclusion of a stated integer or stated integers but not to exclude any other integer or any other integers, unless in the context or usage an exclusive interpretation of the term is required.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A management system for use in compression engines wherein the management system comprises the steps of: measuring engine demand of a compression engine; and regulating flow of a gas phase fuel injected into the air intake of said compression engine in response to the measured engine demand.

2. A gas phase fuel supply for a compression engine wherein the supply comprises a tank, a regulator, an engine demand sensor and an injector, said injector being adapted to spray a gas phase fuel into an air intake of a compression engine, wherein the demand sensor is controllingly connected to the regulator whereby a regulated supply of gas phase fuel is supplied to the injector from the tank.

3. In a third broad form there is provided a compression engine comprising: a combustion chamber for receiving and combusting fuel; at least one fuel inlet into the combustion chamber; at least one air intake valve to allow air into the combustion chamber; an exhaust valve to allow combustion products to exhaust from the combustion chamber; and at least one injector to spray a gas phase fuel into the air intake before said air enters the combustion chamber wherein the gas phase fuel is regulated in response to engine demand.