HK1105443B - Fuel delivery system for engine - Google Patents

Description

Fuel delivery system for engine

The application is a divisional application, the application date of the corresponding parent application is 4-9.2002, the application number is 02811591.0, and the invention is named as a fuel delivery system.

Technical Field

The present invention relates to a fuel delivery system. In one embodiment of the invention, the fuel delivery system delivers liquefied gas to a compression ignition engine for mixing with diesel fuel. In another embodiment, the present invention delivers liquefied gas to a spark ignition engine as a dedicated fuel. In the present specification, the term "liquefied gas" means a liquefied petroleum gas, liquefied natural gas, any number of methanol/ethanol and propane and butane mixtures, and other similar fuels.

Background

It is known that in order to reduce fuel consumption and reduce fuel costs, liquefied petroleum gas can be supplied to the cylinders of a diesel engine together with diesel oil.

Australian patent application No. 71909/00 describes a fuel delivery system which successfully delivers lpg gas and diesel fuel together in controlled proportions into an engine and ensures proper operation of the engine.

Disclosure of Invention

The present invention relates to a further improvement in such a delivery system, which, while suitable for use in diesel engines, is suitable for use in other types of engines, such as those utilizing an electric spark ignition process or a compression ignition process.

According to the present invention, there is provided a fuel delivery system for an engine, comprising:

a diesel fuel delivery device for delivering diesel fuel to the engine;

a second fuel delivery device for delivering liquefied gas to an engine simultaneously with the diesel fuel, the second fuel delivery device comprising:

injecting the liquefied gas into an injector of the engine;

a control device for controlling the fuel injector;

means for maintaining the liquefied gas fuel in a liquid state after the liquefied gas fuel leaves the storage vessel and while the liquefied gas is in the oil injector, such that the liquefied gas fuel is injected in the liquid state by the oil injector, and

a fuel bubble collection system, the collection system comprising:

means for collecting vapor bubbles from the liquefied gas generated when the liquefied gas is supplied to the oil jet;

a liquefied gas system for receiving the bubbles and removing bubbles from the liquefied gas; and

a return means for returning the bubbled liquefied gas in vapor form to the engine.

Preferably, the oil injector injects the liquefied gas into an intake manifold of the engine.

Preferably said means for delivering said diesel fuel to said engine also delivers said diesel fuel to an intake manifold of said engine or to a cylinder of the engine.

Preferably, the fuel injector comprises an injector housing and an injector body within the housing.

Preferably, the control means receives information from one or more of the following detection means:

a fuel sensor that detects a temperature of liquefied gas supplied to the engine;

fuel pressure detecting means for detecting a pressure of the liquefied gas supplied to the injector;

an engine temperature detection device that detects the engine temperature;

air temperature detecting means that detects a temperature of air delivered to the engine through an air inlet;

a throttle position detecting device that detects a position of an accelerator pedal;

a cam angle sensor that detects a position of the engine cam; or

An engine inlet pressure detection device that detects inlet air pressure to the engine.

According to another aspect of the present invention, there is provided a fuel delivery system of an engine, comprising:

a diesel fuel delivery device for delivering diesel fuel to the engine;

a second fuel delivery device for delivering liquefied gas to an engine simultaneously with the diesel fuel, the second fuel delivery device comprising:

injecting the liquefied gas into an injector of the engine;

control means for controlling said injector, and

means for maintaining the liquefied gas fuel in a liquid state after the liquefied gas fuel leaves the storage vessel and while the liquefied gas is in the oil injector, such that the liquefied gas fuel is injected in the liquid state by the oil injector,

wherein the means for maintaining the liquefied gas fuel in a liquid state comprises a housing for receiving liquefied gas;

the fuel injector is mounted in the housing and has a liquefied gas fuel inlet for admitting the liquefied gas into the fuel injector and a liquefied gas fuel outlet for injecting liquefied gas from the fuel injector into the engine cylinder;

a chamber in the housing at least partially surrounding the oil injector, the chamber also for receiving liquefied gas to cool the oil injector around the oil injector for maintaining the liquefied gas in the oil injector in a liquid state for ejection from the oil injector;

an outlet on the chamber allowing vapour and any liquefied gas in the chamber to exit the chamber; and

a pressure regulator for regulating the pressure of the vapour and liquefied gas within the chamber to maintain cooling of the injector using vaporisation of liquefied gas in the chamber;

a vaporizer connected to the outlet for maintaining vapor from the chamber in a vapor state and converting any liquefied gas received from the chamber to a vapor state; and

a vapor delivery section to deliver the liquefied gas in a vapor state to a cylinder of the engine.

According to another aspect of the present invention, there is provided a fuel delivery system of an engine, comprising:

a first fuel delivery means for delivering a first fuel to the engine, the first fuel being diesel fuel; and

a second fuel delivery means for delivering a second fuel from the storage vessel to the engine simultaneously with the first fuel, wherein the second fuel delivery means comprises:

injecting the second fuel into an injector of the engine;

control means for controlling said injector, and

an inlet line providing communication between the storage vessel and the fuel injector;

wherein the second fuel is a liquefied gas fuel that exits the storage vessel in a liquid state;

the second fuel delivery means comprises maintaining means to maintain the temperature and pressure of the second fuel in the inlet line such that the second fuel remains at least partially in the liquid state; and

the second fuel delivery means includes means for preventing vaporization and foaming of said second fuel in said fuel injector so that said second fuel is ejected from said fuel injector in a liquid state.

Preferably, the fuel injector injects the second fuel into an intake manifold of the engine.

Preferably, the first fuel delivery means delivers the first fuel to an intake manifold of the engine or to a cylinder of the engine.

Preferably, the fuel injector comprises an injector housing and an injector body within the housing.

Preferably, the preventing means comprises a fuel bubble collecting system comprising:

means for collecting, from the second fuel, vapor bubbles generated when the second fuel is supplied to the oil jet;

a system for receiving the bubbles and converting them to vapor; and

a conduit for supplying the steam to the engine.

A first aspect of the invention relates to a fuel delivery system for an engine, comprising:

a fuel delivery arrangement for delivering a first fuel to the engine;

a second fuel delivery device for delivering liquefied gas to an engine simultaneously with the first fuel, the second fuel delivery device having:

injecting the liquefied gas into an oil nozzle of the engine;

and a control device for controlling the oil nozzle.

It has been found that the use of a fuel injector for delivering liquefied gas can be used to successfully deliver liquefied gas to an engine and also to overcome the problems inherent in delivering gaseous fuels to an engine simultaneously with other fuels.

In one embodiment, the fuel injector injects liquefied gas into an intake manifold of the engine.

In one embodiment, the means for delivering primary fuel to the engine also delivers primary fuel to an intake manifold of the engine or to a cylinder of the engine.

In one embodiment, the primary fuel is a fuel for a diesel engine, in which case the fuel is delivered to the cylinders of the engine.

In one embodiment, the fuel injector comprises:

an injector body;

a pintle (pintl), a bore in the injector body for receiving the pintle, a pintle seat defining an orifice (orifice) closed by the pintle;

means for moving the pintle away from the pintle seat such that liquefied gas supplied to the injector body may exit the injector body through the orifice.

In one embodiment, the means for moving the pintle comprises an electrical coil which is energized to move the pintle away from the pintle base.

In one embodiment, a biasing means is provided to press the pintle against the pintle seat such that when the electrical coil is energized, the electrical coil forces the pintle away from the seat against the bias of the biasing means.

In one embodiment the injector comprises an injector housing in which the injector body is located, the injector body having an opening in the form of an inclined narrow bore allowing liquefied gas to pass through the opening and into the bore.

Preferably the housing has an inlet for supplying liquefied gas together with the injector housing which defines a chamber around said injector housing so that liquefied gas can flow into the chamber and then through said opening and into said bore.

In one embodiment, the fuel delivery system has a collection system comprising:

means for collecting vapour bubbles from the liquefied gas, said vapour bubbles being generated when the liquefied gas is supplied to the injector;

a liquefied gas system for receiving the vapor bubbles and removing bubbles from the liquefied gas;

and a returning device for returning the bubble-removed liquefied gas to the engine in the form of vapor.

In one embodiment, the delivery system has a conduit leading from the injector up to the system so that naturally rising gas bubbles will flow up through the pintle to the collection system.

In one embodiment of the invention, an engine control unit is provided that collects parameters relating to the engine to control the liquefied gas injectors.

The engine control unit may comprise the engine control system of the engine or a separate processing part.

In one embodiment, the engine control unit receives information from one or more of the following sensing devices:

a fuel sensor that detects a temperature of the liquefied gas supplied to the engine;

fuel pressure detecting means for detecting a pressure of the liquefied gas supplied to the fuel injection nozzle;

an engine temperature detection device that detects an engine temperature;

gas temperature detection means for detecting a temperature of gas delivered to the engine through the air inlet;

throttle position detecting means for detecting a position of an accelerator pedal;

a cam angle sensor that detects a position of a cam of the engine;

engine inlet pressure detecting means for detecting an inlet gas pressure to the engine;

in one embodiment the engine control unit receives parameters from some or all of the above mentioned sensing means and controls the liquid gas injector by providing suitable signals to the electronic coil corresponding to the data received from these sensors.

A second aspect of the invention relates to the structure of the liquefied gas injection nozzle used in the invention;

this aspect of the invention relates to a liquefied gas injection nozzle for injecting liquefied gas into an engine, comprising:

an injector body;

a bore formed in the injector body, the bore having a pin seat defining an orifice;

a needle disposed within the bore, seated on the needle mount, closing the orifice, the needle being removable from the needle mount to open the orifice and allow the liquefied gas to exit the injector;

means for moving said needle latch between a position removed from said needle latch seat and a position seated against said needle latch seat, thereby selectively opening and closing said injector;

an opening in the injector body communicating with the bore to ensure that liquefied gas enters the injector body through the opening and into the bore in a direction perpendicular to the direction of the pintle;

a passage through the injector body extending from the orifice to an upper portion of the injector body ensures that gas bubbles pass through the orifice and the passage from near the opening to the upper portion of the injector body.

In one embodiment, the control means includes an electrical coil which is energised to pull the tumbler away from the pin holder, and which is de-energised to ensure that the pin is returned to the pin holder.

In one embodiment, the injector body includes a biasing device that biases the pin against the pin seat.

In one embodiment, the passage comprises an injector chamber disposed above the needle into which gas bubbles generated during the ejection of lpg gas from the injector can flow upwardly.

In one embodiment, the chamber is connected to a liquefied petroleum gas vaporization system for receiving and eliminating gas bubbles from the liquefied petroleum gas prior to returning the liquefied petroleum gas to the engine.

In one embodiment of the invention, the vaporization system returns the debubbled liquefied gas to the engine as a vapor, however in other embodiments the vapor may be returned to other locations.

Another aspect of the invention relates to the elimination of bubbles from the liquefied gas supplied to the engine.

This aspect of the invention relates to a fuel delivery system of an engine, comprising:

a liquefied gas supply device for supplying liquefied gas to the engine;

collecting means for collecting vapor bubbles in the liquefied gas, the vapor bubbles being generated when the liquefied gas is supplied to the engine;

return means for returning the vapour to the engine intake manifold.

This aspect of the invention also relates to an oil injector for delivering liquefied gas to an engine, comprising:

an oil nozzle body;

the hole on the oil nozzle body

A pin holder formed on the hole to define a nozzle hole;

a needle disposed within said bore for seating against said needle seat to close said orifice and prevent the exit of liquefied gas through said orifice, said needle being removable from said needle seat to allow the exit of liquefied gas through said orifice;

control means for moving said pin towards and away from said pin seat;

a bubble flow path in the body of the injector for collecting liquefied gas bubbles generated when liquefied gas is discharged from the injector.

In one embodiment, the path comprises:

a cavity defined between the pin and a wall defining the bore;

the injector has an upper collection chamber therein for receiving gas bubbles for supply to the liquefied gas vaporization system.

In one embodiment, the vaporization system includes a conduit connected to the upper collection chamber through which bubbles can rise from the upper collection chamber to the vaporization system where they are removed and the liquefied gas from which bubbles have been removed is returned to the engine inlet in a vapor state.

Preferably the injector body includes a cooling outlet and a cooling inlet so that coolant can flow into the inlet, then into said body and around the injector body and then out through the cooling outlet.

Another aspect of the invention relates to the boiling (buckling) and evaporation of liquid when fuel is delivered to an engine using a fuel delivery system. In a common liquefied petroleum gas delivery system for delivering liquid to an engine, such as an ordinary vehicle engine, or in combination with diesel fuel to a diesel engine, liquefied gas is supplied to the intake manifold of the engine, where it evaporates and is drawn into the engine cylinders along with air for ignition. It is necessary to deliver liquefied gas to the engine in this manner, since liquefied gas is normally at a high pressure and relatively cold in the liquefied gas tank, and when supplied from the liquefied gas tank, it evaporates at room temperature, making it virtually impossible to deliver fuel to the engine other than in the form of vapour.

It is thus a common way of supplying liquefied gas to the inlet port (intake) where it simply evaporates and is drawn into the engine together with the inlet air. As the fuel leaves the cold and high pressure environment of the fuel tank and is supplied to the air inlet, the fuel evaporates in the form of fuel boiling. This evaporation or boiling produces fuel bubbles, which we have found in the prior art cannot deal with the delivery of this type of fuel, nor can it be simply delivered to the air inlet without the evaporation causing any difficulties. In this delivery form, the fuel is simply drawn into the engine without any delivery control. This form of liquefied gas is therefore very inefficient to supply. Since lpg is inexpensive, in the past, these deficiencies could be tolerated without creating any particular difficulties. However, as the cost of liquefied petroleum gas increases, highly efficient fuel delivery systems are desired.

This aspect of the invention provides a fuel delivery system for delivering liquefied gas to an engine cylinder, the fuel delivery system comprising:

a supply device for supplying liquefied petroleum gas;

an injector for receiving liquefied gas from the supply and discharging said liquefied gas in liquid form into an engine cylinder;

and a preventing means for preventing the liquefied gas in the oil jet from evaporating or boiling, whereby the liquefied gas is discharged from the oil jet in a liquid form.

In one embodiment of the invention the inhibiting means comprises cooling means for cooling the liquefied gas so that the temperature of the liquefied gas delivered to the injector and the liquefied gas discharged from the injector is lower than the temperature of the liquefied gas in the liquefied gas supply means so that the liquefied gas does not evaporate or boil in the injector.

Preferably the cooling means comprises a liquefied gas delivery line for supplying liquefied gas to the injector for cooling the injector.

Preferably, the fuel injector comprises:

an injector body for receiving the supplied liquefied gas and discharging the liquefied gas from the injector body;

a housing surrounding the injector body, said housing defining a chamber between said housing and the injector body;

the cooling device further comprises a coolant inlet opening and a coolant outlet opening in the housing, said inlets being connected to coolant supply means so that coolant can be supplied into said chamber and around the injector body for cooling the injector body and the liquefied gas in the injector body.

Preferably the coolant is a low pressure liquefied petroleum gas liquid, but any suitable coolant may be used.

In a preferred embodiment of the invention, the inhibiting means comprises bubble removing means for removing bubbles generated in the liquefied gas before being supplied to the oil jet.

Preferably the bubble removal means is combined with cooling means for cooling the liquefied gas so that the liquefied gas delivered to the injector is maintained at a low temperature, at least to reduce the likelihood of boiling or vaporisation on injection.

Preferably the injector is provided with a housing comprising a bubble elimination passage for ensuring rising of bubbles and vapour, the injector being located in the housing below the passage and being connected to a first bubble elimination mechanism for reducing the pressure of the liquefied gas on which bubbles and evaporation occur, a conduit extending from said first bubble elimination mechanism to a second bubble elimination mechanism outside the housing for converting the liquefied gas into a pure vapour state.

Preferably the injector communicates with the engine inlet and the second bubble removal means is connected to the engine inlet by a second conduit whereby the injector discharges liquefied gas sprayed from the injector and the second conduit delivers liquefied gas in vapour form from the second bubble removal means.

This aspect of the invention also relates to a fuel delivery system for delivering liquefied gas to an engine cylinder, comprising:

a liquefied gas supply device for supplying liquefied gas;

a plurality of injectors for receiving the liquefied gas from the supply means and discharging the liquefied gas to the cylinders;

cooling means for cooling the liquefied gas supplied to the fuel injector so that the liquefied gas is maintained at a temperature lower than the temperature of the liquefied gas in the supply means, thereby preventing bubbling or boiling of the liquefied gas in the fuel injector so that the liquefied gas can be discharged from the fuel injector in liquid form.

Another aspect of the invention also relates to a liquefied gas system.

This aspect of the invention may relate to a liquefied gas system for receiving bubbles of liquefied gas and converting the bubbles to a liquid or vapor state for return to a collection point, comprising:

a chamber for receiving the bubble;

a float within the cavity;

a switching element connected to the float;

a cooperating switch element which is actuated by the switch element when the float is in a predetermined position;

an outlet of the chamber;

a valve for closing the outlet;

when a bubble enters the chamber, the bubble may collapse and return to a liquid or vapor state on which the float floats;

when a pressure builds up in the chamber due to the supply of bubbles into the chamber and the formation of liquid or vapour from the collapse of the bubbles, the float is pushed by the pressure to a predetermined position whereby the switch member actuates a corresponding switch member, opening the valve, allowing vapour to pass from the outlet to the collection station.

In one embodiment of the invention, the collection station may simply be the engine intake manifold, so that after the bubbles are eliminated, the vapor may be returned from the vaporization system to the engine.

In yet another embodiment of the invention, the vapor or liquefied petroleum gas may be returned to another location for use or storage.

In one embodiment of the invention, the valve includes a solenoid valve, and when the float is in a predetermined position, the sensor is activated to open the solenoid valve to ensure vapor passage through the outlet.

In one embodiment, the switch element includes a magnet associated with the float and the cooperating switch element includes a sensor that senses the magnet such that when the float is moved to a predetermined position, the magnet is adjacent the sensor, energizing the sensor, thereby opening the valve.

The liquefied gas used in all the above aspects of the present invention may be liquefied petroleum gas or compressed liquefied natural gas.

If liquefied petroleum gas is used, the preferred embodiment of the invention also includes, prior to the fuel delivery system:

the heat exchange device is used for receiving the compressed natural gas and cooling the natural gas;

and the pressure reducing device is used for reducing the pressure of the compressed natural gas before the compressed natural gas is conveyed to the fuel conveying system.

A filter may be provided between the heat exchanger and the pressure reduction device.

Another aspect of the invention relates to a fuel and fuel delivery system for two-stroke.

This aspect of the invention may relate to a fuel comprising liquefied gas mixed with oil.

Preferably the fuel comprises liquefied petroleum gas and the oil is a two-stroke oil.

In this preferred embodiment of the invention, a mixture of liquefied petroleum gas and oil can be injected into a two-stroke engine, with the advantage that the liquefied petroleum gas which evaporates when injected into the engine allows the "dry" oil to be coated onto the mechanical components of the engine for lubrication. The vaporized lpg gas may be drawn into the chamber of the two-stroke engine for combustion.

This aspect of the invention may also relate to a fuel delivery system as described above, wherein the fuel comprises a mixture of liquefied petroleum gas and two-stroke oil (two stroke oil).

Preferably the oil injector used in this aspect comprises a bleed off line which is heated by the heat of the engine and arranged to drain any oil in the injector.

Preferably the bleed line communicates with the crankcase of the engine in which the fuel delivery system is installed.

The invention also provides a fuel comprising an alcohol mixed with a liquid hydrocarbon that readily evaporates at standard temperature and pressure.

Preferably, the alcohol is methanol or ethanol and the liquid hydrocarbon is butane or propane.

Preferably said fuel comprises water.

Drawings

A preferred embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a schematic view showing an embodiment of the present invention that may be adapted for use in an electric spark ignition engine or a compression ignition engine;

FIG. 2 is a diagram illustrating in greater detail one embodiment of a vapor system used in the embodiment shown in FIG. 1;

FIG. 3 is a view schematically showing a preferred embodiment of the present invention;

FIG. 4 is a view showing a portion of the embodiment of FIG. 3;

FIG. 5 is a detail view, assembled, of the components of FIG. 4 attached to the intake manifold and thus to the cylinder head of the compression ignition engine in a convenient correct operating orientation;

FIG. 6 is a top cross-sectional view showing four injection devices properly aligned with intake ports of the cylinder head and connected to the intake manifold;

FIG. 7 is a schematic view showing another embodiment of the present invention, specifically an embodiment for supplying liquefied natural gas to an engine;

fig. 8 is a schematic view showing another embodiment of the present invention, specifically an embodiment for supplying fuel and lubricating oil to a two-stroke engine.

Detailed Description

The fuel delivery system 10 shown in fig. 1 includes a liquefied petroleum gas cylinder 12 for storing liquefied petroleum gas. The cylinder 12 has a fuel cut off valve 14 and an output line 16 for supplying lpg gas through a filter lock valve 18 to an lpg gas injector 20. The injector 20 has an injector body 22 with an electrical coil 24 disposed thereon. The injector body 22 is provided with an aperture 26 in which a pin 28 is located.

The pin 28 is slightly loosely fitted within the bore 26. At the lower end of the bore 26 is a pin holder 30 defining a nozzle hole 31 leading to an intake manifold 32 of the engine E. The engine E has an exhaust 34. The bore 26 has an upper end 35 and a spring 36 is located between the upper end 35 and the pin 28 to bias the pin 28 against the pin seat 30 to close the bore 31 leading to the intake manifold 32.

The injector body 22 has an injector chamber 40 communicating with the bore 28 through a narrow passage 37, the narrow passage 37 extending from the end 35 to the chamber 40. The chamber 40 is connected to a rising bubble line 44, and the rising bubble line 44 is connected to a liquefied petroleum vapor system 48, which will be described in detail below. The liquefied petroleum vapor system 48 has a vapor line 50 extending from the liquefied petroleum vapor system 48 back to the intake manifold 32 for supplying vapor back to the intake manifold 32, as will be described in greater detail below.

The intake manifold 32 has an air inlet 60, and a universal throttle device 62 for an electric spark ignition engine is disposed within the air inlet 60. In the compression ignition engine, the throttle device 62 is not provided.

The system shown in fig. 1 is controlled by an engine control unit 70, which engine control unit 70 may be an on-board computer or engine control system associated with the engine E. Input parameters from the fuel system and the engine are provided to the control unit 70 for processing and control purposes. The fuel temperature sensor 72 monitors the temperature of the fuel in the liquefied petroleum gas cylinder 12. A pressure sensor 74 monitors the fuel delivery pressure through line 16. A throttle position sensor 76 monitors the throttle position of the throttle device 62 and a temperature sensor 78 monitors the temperature of air entering the intake manifold 32 through the air intake 60. Another pressure sensor 80 monitors air pressure at the intake manifold 32, and RPM and cam position sensors 82 measure engine rotation and cam position to control intake valves of the engine E.

The engine E control unit 70 also has an output line 84 for controlling the check valve 14 and an output line 86 for energizing the coil 24 of the injector 20.

The injector body 22 includes two inclined slots 90 (only one shown) formed in the nozzle body wall which communicate with the bore 26 leading to the bore 31. A housing (not shown) surrounds the injector body 22 and has an inlet for receiving the conduit 16 so that liquid petroleum gas can be supplied into the housing and then through the slot 90 into the bore 26 in a direction transverse to the pintle 26 for supplying gas to the engine E. When the engine control unit outputs a pulse on line 86 to energize the coil 24, the pin 28 is pulled away from the pin holder 30 against the spring force of the spring 36, thereby opening the hole 31. The liquefied petroleum gas in the bore 26 is injected from the nozzle body into the intake manifold 32 and is provided to the engine E. When the control unit 70 cancels the pulse on line 86, the coil 24 is de-energized and the needle 28 seats against the needle hub 30 to close the orifice.

The natural vaporization or evaporation of the liquefied petroleum gas leaving the high pressure and relatively low temperature environment of the cylinder 12 and being supplied to the higher ambient temperature region causes the liquefied petroleum gas to bubble. Such a temperature change is thus effective to ensure that the liquefied petroleum gas vaporizes as it is converted from the liquid state to the gaseous state. The lpg gas is thus effectively admitted from a direction transverse to the direction of movement of the pin 26 and the pin, rather than from a direction substantially parallel to the pin 26 as is the case with conventional fuel injector systems. So that a bubble which naturally tends to rise will rise upwardly from the vicinity of the aperture 26, through the spring 36, and then through the narrow passage 37 into the ejection chamber 40. The bubbles can then flow through the up-bubble line 44 to the transducer 48.

The transducer 48 provides a relatively large volume of low pressure and relatively high temperature chamber so that bubbles entering the transducer 48 can simply collapse and be converted to a vapor state due to the relatively low pressure and high ambient temperature. The vapor may then be provided along line 50 to the air intake 32 of the engine E. Alternatively, the vapor may be delivered to another environment where it is stored for later use.

The transducer 48 may be replaced with a bubble elimination chamber as shown in fig. 2, which includes a housing 100 defining a transducer chamber 102. The housing 100 has an inlet 104 connected to the conduit 44 so that bubbles within the conduit 44 can enter the inlet 104 and enter the cavity 102. A float 106 is located within the chamber 102, with a magnet 108 carried on the underside of the float 106.

A pair of proximity switches 110 and 112 are secured to the housing 100, the switches 110 or 112 being actuated by the magnet 108 when the magnet 108 is moved to a position adjacent the respective switch 110 or 112.

As bubbles of liquefied petroleum gas flow into chamber 102 through inlet 104, the bubbles can collapse and reform as liquid or vapor within chamber 102, and as pressure builds up due to the rise of the bubbles through conduit 44, the vapor pressure, which naturally tends to move above the liquid surface, will tend to push float 106 downwardly in the direction indicated by arrow a in fig. 2, so that float 106 moves from a position adjacent switch 110 to a position adjacent switch 112. When magnet 108 is adjacent switch 112, switch 112 is activated.

The chamber 102 has an outlet 114, and a solenoid valve 116 is disposed within the outlet 114 for selectively opening or closing the outlet 114. The outlet 114 is then connected to the conduit 50 shown in figure 1. When magnet 108 is pushed by vapor pressure within chamber 102 so as to be adjacent switch 112, switch 112 is activated as described above, and activation of switch 112 activates solenoid valve 116 to open valve 116.

Opening valve 116 allows vapor within chamber 102 to pass through valve 116 to vapor line 50 for return to intake manifold 32 and then to be provided to engine E. With the vapor released, the liquid level within the chamber 102 can rise, the float 106 can return to the position shown in FIG. 2, and the switch 112 is deactivated. The magnet then abuts switch 110, switch 110 then indicating an inactive state, and valve 116 is closed until pressure builds again pushing float 116 and the magnet 108 to a position adjacent switch 112.

This embodiment of the invention is thus able to cope with bubbles generated when the lpg gas is ejected from the injector 20 under pressure, which can be collected and eliminated and then returned to the engine as fuel.

In this embodiment of the invention, to reduce the amount of evaporation of fuel injected from the fuel injectors 20 into the engine E, the intake manifold 32 is preferably cooled by water passages or other coolant passages extending through the intake manifold 32. This maintains the intake manifold 32 at low temperatures and protects the lpg fuel from the radiant heat of the engine E, thereby maintaining the lpg gas primarily in a liquid state. The cooling passages through intake manifold 32 may be connected to a vapor converter system of the type shown in FIG. 2 but containing liquid cooling, whereby cooling liquid is circulated from the vapor converter to intake manifold 32.

A sensor 80 that measures the pressure in the intake manifold 32 provides a signal to the unit 70. Throttle position sensor 76 and sensor 80, and taking into account air temperature, are monitored by unit 70, which unit 70 in turn controls the amount of lpg liquid injected through intake manifold 32. Equal spraying (equi-volume spraying) of each of the engine injectors of the engine is achieved by using an equidistant path length from the needle mount 30 to the vapour system 48 for each injector, by the first in last out principle. The number of injectors of the lpg gas liquid injection system will depend on the number of cylinders of the diesel engine, but this is not necessarily the case for spark ignition engines. Pulse width modulation (pulse width modulation) of the nozzle supplying on line 86 to operate coil 24 is controlled based on engine load, RPM, temperature, intake air temperature, fuel temperature, throttle position under pressure, acceleration and deceleration transient boost pressure, all of which are determined by unit 70. The unit 70 is in turn programmed to provide all RPM settings, predetermined fuel quantities introduced (diesel engine referred to dg blend) to achieve specific power curves, emission standards and economy. On a diesel engine, the cam angle sensor 82 provides time sequential injection. I.e. when the exhaust valve is opened, no lpg gas is present, and when it is closed and the inlet valve is opened, lpg gas is introduced in sequence. The engine temperature is monitored to ensure that the temperature cooled mixture is correct, as per the specifications of unit 70, to ensure that control of emissions is achieved.

In this embodiment of the invention, steam is applied from the system 48 through the conduit 50 to flush (flush) the end of the needle 28 adjacent the orifice 31 and near the orifice 31.

In the case of a compression ignition system, the timed sequential injection of each injector 20 is ensured so that there is no lpg gas in the scavenging air. The sensor 80 is designed such that its signal provided to the engine control means in the form of a raw equipment manufacturing engine control unit is modified to obtain a controlled reduction in diesel usage. The sensor may be disabled if it is desired to run the engine using only diesel fuel, rather than a mixture of diesel fuel and liquefied petroleum gas.

A more preferred embodiment of the present invention is described below with reference to FIGS. 3-6. Rather than relying solely on the collection of bubbles being formed in this embodiment, this embodiment preferably initially prevents or at least greatly reduces the likelihood of bubble formation, thereby ensuring that the lpg gas is injected in liquid form from the injector 20. In fig. 3-6, like reference numerals refer to like elements that have been described above.

In the embodiment shown in fig. 3-6, the supply of liquefied petroleum gas is carried out in another manner as will be described in more detail below. Thus, in this embodiment, the slot 90 need not be provided, or if the slot 90 is provided, a single form of nozzle 20 may be used with the embodiments shown in FIGS. 1 and 2 and 3-6, with the slot 90 being closed to prevent the escape of liquefied petroleum gas from the nozzle body 22. The lpg gas is delivered axially through the nozzle body 22 in a conventional manner rather than transversely as shown in fig. 1.

Referring to fig. 3, the lpg tank 12 supplies lpg gas through a tank lock 14 to an inlet line 16 and into an on-line filter 4, the filtered lpg gas then being delivered through an inlet line 37 to a distribution block 38. From the distributor block 38 the lpg gas flows through an isolated delivery line 39 to the injector housing 3 (shown in more detail in figures 4 and 5).

Referring to fig. 4, the lpg gas from line 39 enters a respective weir T (weir Tpiece)8 in each housing 3. The liquefied petroleum gas flows upward to the shut-off valve 9 controlled by the shut-off valve solenoid 5. When energized on circuit 127 by ECU70, the interrupter valve solenoid 5 opens.

When the shut-off valve 9 is opened, bubbles of liquefied petroleum gas liquid and steam flow through the shut-off valve 9, the liquid falls by gravity to the injector inlet 201, and the bubbles rise to the converter inlet 11.

As best shown in fig. 4, the injector housing 3 supports the injector 20 and carries gas bubbles away from the injector inlet 201. The injector housing 3 also provides cooling to the injector 20 to maintain the fuel in the injector 20 in a liquid state, thereby preventing the fuel from switching to a vaporized or bubbled state within the injector 20.

With liquid at the injector inlet 201 and pulse width provided from the ECU70, the lpg gas passes through the injector 20 and is injected into the intake manifold 32 (see figure 5) with the jet directed towards the inlet port 29 (see figure 5). The injection of lpg gas is timed by the ECU70 so that a pulse is generated after the exhaust valve 133 closes (see figure 5) and before the intake valve 132 closes (see figure 5) so that the downward action of the piston 131 (see figure 5) can pull all of the injected lpg gas into the engine E without being blown out through the exhaust valve 133.

As the lpg gas falls into weir T8, supplying lpg gas to the injector inlet 201, any existing or formed vapour bubbles rise to the converter inlet 11 and depressurise in the chamber 203 within the housing 3. The case 3 has a cap portion 203a closed by the septum 202. The diaphragm 202 forms one wall of the cavity 203 and the spring 205 biases the diaphragm 202 inwardly toward the cavity 203. The diaphragm 202 carries a connecting rod 206 connected to a flat valve 207, said flat valve 207 closing the inlet 11 according to the pressure inside the chamber 203. As best seen in fig. 4, the oil jet 20 is mounted in the chamber 203 and has an inlet 201 supported on a platform 251, the central portion 20a of which is sealed by wall members 252 and 253 of the chamber 203. The outlet end of the injector 20 is sealed by an aperture 256 exposed to the cavity of the intake manifold 32 of the engine E.

The pressure of the liquefied gas supplied to the inlet 11 through the weir T8 is significantly higher than the pressure inside the chamber 203, which pushes the valve 207 open against the diaphragm 202 and biases the spring 205 so that bubbles and vapour generated in the liquefied gas supplied to the inlet 201 will rise and flow into the port 11 and into the chamber 203. The reduced pressure in chamber 203 allows the bubbles to collapse and any liquid that enters chamber 203 is converted to vapor, thereby cooling the injector 20 exposed to chamber 203. Cooling of the injector 20 ensures that the liquid petroleum gas entering the inlet 201 is maintained in a liquid state due to the cooling state of the injector 20 and is not converted to vapour within the injector 20 which would impair operation of the injector 20 and prevent proper discharge of fuel from the injector 20. In the event that the pressure in the chamber 203 rises above the pressure of the liquefied petroleum gas at the inlet 11, the diaphragm 202 in figure 4 is pushed upwards against the bias of the spring 205 causing the lever 206 to cause the flat seat valve 207 to close off the inlet preventing further entry of bubbles and vapour into the housing 203 until the pressure in the housing 203 drops due to the outflow of liquefied petroleum gas from the housing 203 through the outlet line 209. Thus, the vapour and liquid of reduced pressure in chamber 203 has a cooling effect on the housing 3 and the injector 20. The cooling effect is required to reduce the likelihood of evaporation of the liquid petroleum gas within the injection system, and in particular within the injector 20. After the housing 3 and injector 20 are cooled sufficiently so that the low pressure lpg gas does not evaporate, the remaining lpg gas enters line 209 and is delivered to the vapour block 208. The block 208 includes an aperture 118. The orifices 118 restrict the flow of lpg gas and create a back pressure to control the amount of lpg gas vapour entering the engine through line 119. The vapor block 208 has a hot water inlet 120 and a hot water outlet 121, and holes (not shown) extend through the block 208 to heat the block so that the fuel within the block 208 remains in a vapor state. The inlet 120 and outlet 121 are connected to a heater circuit within the vehicle cabin to maintain the block 208 at the engine coolant temperature. While block 208 is at engine coolant temperature, the low pressure lpg gas cannot be maintained in liquid form, preventing inadvertent supply of lpg gas via block 208, so that only vapour is supplied to the engine through line 119.

In another embodiment, block 208 may be equipped with second stage orifice 117 and a solenoid valve 116 so that varying amounts of vented vapors may be supplied to the engine through line 119. ECU70 controls solenoid valve 116 via circuit 125.

Block 208 may also contain a coolant temperature sensor 123 that feeds engine temperature information back to ECU70 through loop 124.

Figures 5 and 6 also show a diesel injector 171 for supplying lpg gas to the cylinders of engine E and diesel oil to the cylinders of engine E via injector 20 and line 119. Thus, by supplying fuel in the form of lpg gas from injector 20 and line 119, the amount of diesel fuel required to be supplied can be reduced, increasing fuel economy compared to what would occur if diesel fuel were supplied solely through diesel injector 171.

In fig. 7, a standard compressed natural gas tank 400 is shown filled with natural gas from a compressed natural gas supply station 401 via line 402. The compressed natural gas pressure within compressed natural gas tank 400 mounted on a vehicle is typically on the order of 3000 psi. The compressed natural gas from the tank 400 is supplied to the air conditioning heat exchange unit 404 so as to lower the temperature of the compressed natural gas supplied from the tank 400, keeping the compressed natural gas in a cold state. The compressed natural gas is then supplied to a filter 406 to remove undesired materials and contaminants within the compressed natural gas, and then supplied to a pressure regulator 408 to reduce the pressure of the compressed natural gas to about 100 psi. Since the compressed natural gas has been cooled by the air conditioning unit 404, the pressure may be reduced to a level that still maintains the compressed natural gas in a liquid state. The compressed natural gas is then supplied to a heat exchanger 410 and then through a fuel line 412 to each of the same housings 3 as described in connection with fig. 3-6. The housing 3 also includes a fuel injector 20 in the manner described above, which is cooled in the same manner as described above, the fuel within the injector being maintained in a liquid state for ejection from the injector. Any bubbling fuel from the housing 3 passes through the heat exchanger 410 on line 209 to exchange heat with the fuel in line 412, helping to maintain the fuel in line 412 in a cold state. The conduit 209 is then connected to an evaporation block 208 that is identical to the evaporation block 208 described above. The vaporized fuel exits the evaporation block through line 119 and is delivered to the intake of the engine in the same manner as described above.

Fig. 8 shows another embodiment of the invention particularly suitable for a two-stroke engine, in this embodiment of the invention the fuel comprises a mixture of liquefied petroleum gas and two-stroke oil (two stroke oil). The two-stroke oil mixes with and is readily mixed with the liquefied petroleum gas so that both the liquefied petroleum gas and the two-stroke oil are delivered from the tank 501 through the fuel line 500 to the housing 3 which has the same structure as the housing 3 described in connection with figures 3 to 6. An oil injector 20 in the housing 3 injects a mixture of liquefied petroleum gas and two-stroke oil into a sump (temp) 512 of the two-stroke engine 550. Engine 550 includes a piston 551 and a crank 552, with piston 551 and crank 552 connected together by a connecting rod 553, as is conventional. Transfer holes 554 allow fuel injected into sump 512 to be pulled into chamber 555 for ignition by spark plugs 556.

This embodiment has the advantage that since the fuel is a mixture of lpg and two-stroke oil, as soon as the fuel is ejected from the injector 20 the lpg evaporates leaving a "dry" two-stroke oil component which can be applied to the operating components of the engine 550 for lubrication. The vaporized liquefied petroleum gas is pushed through transfer port 554 and ignited in chamber 555. The fuel mixture also cools and lubricates these mechanical parts.

In the same manner as the embodiment of fig. 3-6, the conduit 209 extends from the housing 3. However, in this embodiment, the conduit 209 not only drains liquid fuel and vapor that has been de-bubbled within the cavity 203 of the housing 3, but also any two-stroke oil that has accumulated within the cavity 203. The oil and fuel are supplied to a vapor block 208 which is the same as the vapor block 208 in the embodiment of FIGS. 3-8, except that in this embodiment, since the two-stroke engine has no liquid cooling system, no coolant is supplied through the vapor block 208. Rather, the block 208 may simply be heated slightly by the ambient engine temperature due to its proximity to the engine shown in FIG. 8. In the same manner as described above, fuel entering block 208 is converted to vapor form, and the vapor fuel and any two-stroke oil are supplied to the sump 512 of engine 550 via line 119.

In other embodiments of the invention, the fuel used in the fuel delivery system of the internal combustion engine may comprise any proportion of liquefied petroleum gas and methanol/ethanol mixture, any proportion of liquefied petroleum gas, methanol/ethanol and water, which are further mixed with the two-stroke lubricating oil.

In other embodiments, the fuel may comprise an alcohol, such as methanol or ethanol, mixed with a liquid hydrocarbon, such as butane or propane, that readily vaporizes at standard temperatures and pressures. The fuel may also include water other than water already present in the alcohol included in the fuel.

Modifications within the spirit and scope of the invention will be apparent to those skilled in the art, and it should be understood that this invention is not limited to the above-described embodiments.

Claims (10)

1. A fuel delivery system for an engine, comprising:

a diesel fuel delivery device (171) for delivering diesel fuel to the engine;

a second fuel delivery arrangement (20, 3) for delivering liquefied gas to the engine simultaneously with the diesel fuel, the second fuel delivery arrangement comprising:

-injecting the liquefied gas into an injector (20) of the engine;

-control means (70) for controlling said injector;

means (3, 100) for maintaining the liquefied gas fuel in the liquid state after it leaves the storage container (12) and while the liquefied gas is in the oil injector (20), so that the liquefied gas fuel is injected in the liquid state by the oil injector (20), and

a fuel bubble collection system (208), the collection system comprising:

means for collecting vapor bubbles from the liquefied gas generated when the liquefied gas is supplied to the oil jet;

a liquefied gas system (117, 118, 208) for receiving the bubbles and removing bubbles from the liquefied gas; and

a return means (119) for returning the bubbled liquefied gas in vapour form to the engine.

2. The fuel delivery system of claim 1, wherein said fuel injector (20) injects said liquefied gas into an intake manifold of said engine.

3. The fuel delivery system of claim 2, wherein said means (171) for delivering said diesel fuel to said engine also delivers said diesel fuel to an intake manifold of said engine or to a cylinder of said engine.

4. The fuel delivery system of claim 1, wherein said fuel injector (20) comprises an injector housing (252, 253) and an injector body (20a) within said housing.

5. The fuel delivery system of claim 1, wherein the control device (20) receives information from one or more of the following sensing devices:

a fuel sensor (72) that detects the temperature of the liquefied gas supplied to the engine;

fuel pressure detecting means (74) for detecting the pressure of the liquefied gas supplied to the injector;

an engine temperature detection device that detects the engine temperature;

air temperature detection means (78) for detecting the temperature of air delivered to the engine through an air inlet;

a throttle position detecting device (76) that detects a position of an accelerator pedal;

a cam angle sensor (82) that detects a position of the engine cam; or

An engine inlet pressure detection device (80) that detects inlet air pressure to the engine.

6. A fuel delivery system for an engine, comprising:

a diesel fuel delivery device (171) for delivering diesel fuel to the engine;

a second fuel delivery arrangement (20, 3) for delivering liquefied gas to the engine simultaneously with the diesel fuel, the second fuel delivery arrangement comprising:

-injecting the liquefied gas into an injector (20) of the engine;

a control device (70) for controlling the injection nozzle, and

means (3, 100) for maintaining the liquefied gas fuel in a liquid state after it leaves the storage container (12) and while the liquefied gas is in the oil injector (20), so that the liquefied gas fuel is injected in a liquid state by the oil injector (20),

wherein the means (3, 100) for maintaining the liquefied gas fuel in a liquid state comprises a housing for receiving liquefied gas;

the fuel injector is mounted in the housing and has a liquefied gas fuel inlet for admitting the liquefied gas into the fuel injector and a liquefied gas fuel outlet for injecting liquefied gas from the fuel injector into the engine cylinder;

a chamber (203) in the housing at least partially surrounding the injector, the chamber also being adapted to receive liquefied gas so that the liquefied gas cools the injector around the injector to maintain the liquefied gas in the injector in a liquid state for ejection from the injector;

an outlet (209) on the chamber to allow vapour and any liquefied gas in the chamber to exit the chamber (203); and

a pressure regulator (202-207) for regulating the pressure of the vapour and liquefied gas within the chamber (203) to maintain cooling of the injector by vaporisation of the liquefied gas in the chamber;

a vaporizing device (208) connected to the outlet (209) for maintaining vapor from the chamber (203) in a vapor state and converting any liquefied gas received from the chamber (203) into a vapor state; and

a vapor delivery section to deliver the liquefied gas in a vapor state to a cylinder of the engine.

7. A fuel delivery system for an engine, comprising:

a first fuel delivery means for delivering a first fuel to the engine, the first fuel being diesel fuel; and

a second fuel delivery arrangement for delivering a second fuel from a storage vessel (12) to the engine simultaneously with the first fuel, wherein the second fuel delivery arrangement comprises:

-injecting the second fuel into an injector (20) of the engine;

a control device (70) for controlling the injection nozzle, and

an inlet line (16) communicating between the storage vessel (12) and the fuel injector (20);

wherein the second fuel is a liquefied gas fuel that leaves the storage vessel (12) in a liquid state;

the second fuel delivery means comprises maintaining means to maintain the temperature and pressure of the second fuel in the inlet line (16) such that the second fuel remains at least partially in a liquid state; and

the second fuel delivery means includes means for preventing vaporization and foaming of the second fuel in the fuel injector (20) so that the second fuel is ejected from the fuel injector (20) in a liquid state.

8. The fuel delivery system of claim 7, wherein said fuel injector (20) injects said second fuel into an intake manifold of said engine.

9. The fuel delivery system of claim 8, wherein the first fuel delivery device delivers the first fuel to an intake manifold of the engine or a cylinder of the engine.

10. The fuel delivery system of claim 7, wherein said fuel injector (20) comprises an injector housing (252, 253) and an injector body (20a) within said housing.

11. The fuel delivery system of claim 7, wherein the preventing means comprises a fuel bubble trap system (208) comprising:

means for collecting, from the second fuel, vapor bubbles generated when the second fuel is supplied to the oil jet;

a system (117, 118, 208) for receiving said bubbles and converting them into a vapor; and

a conduit (119) for supplying the steam to the engine.