GB2399598A - Multi-pass fuel separation and injection system for i.c. engines - Google Patents
Multi-pass fuel separation and injection system for i.c. engines Download PDFInfo
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- GB2399598A GB2399598A GB0306902A GB0306902A GB2399598A GB 2399598 A GB2399598 A GB 2399598A GB 0306902 A GB0306902 A GB 0306902A GB 0306902 A GB0306902 A GB 0306902A GB 2399598 A GB2399598 A GB 2399598A
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- Prior art keywords
- fuel
- reservoir
- fractioned
- component
- surplus
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D19/00—Degasification of liquids
- B01D19/0073—Degasification of liquids by a method not covered by groups B01D19/0005 - B01D19/0042
- B01D19/0078—Degasification of liquids by a method not covered by groups B01D19/0005 - B01D19/0042 by vibration
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/006—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping by vibration
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
- F02D19/06—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed
- F02D19/0639—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed characterised by the type of fuels
- F02D19/0649—Liquid fuels having different boiling temperatures, volatilities, densities, viscosities, cetane or octane numbers
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
- F02D19/06—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed
- F02D19/0663—Details on the fuel supply system, e.g. tanks, valves, pipes, pumps, rails, injectors or mixers
- F02D19/0668—Treating or cleaning means; Fuel filters
- F02D19/0671—Means to generate or modify a fuel, e.g. reformers, electrolytic cells or membranes
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
- F02D19/06—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed
- F02D19/0663—Details on the fuel supply system, e.g. tanks, valves, pipes, pumps, rails, injectors or mixers
- F02D19/0686—Injectors
- F02D19/0692—Arrangement of multiple injectors per combustion chamber
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
- F02D19/06—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed
- F02D19/08—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed simultaneously using pluralities of fuels
- F02D19/081—Adjusting the fuel composition or mixing ratio; Transitioning from one fuel to the other
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M1/00—Carburettors with means for facilitating engine's starting or its idling below operational temperatures
- F02M1/16—Other means for enriching fuel-air mixture during starting; Priming cups; using different fuels for starting and normal operation
- F02M1/165—Vaporizing light fractions from the fuel and condensing them for use during starting
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M25/00—Engine-pertinent apparatus for adding non-fuel substances or small quantities of secondary fuel to combustion-air, main fuel or fuel-air mixture
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M27/00—Apparatus for treating combustion-air, fuel, or fuel-air mixture, by catalysts, electric means, magnetism, rays, sound waves, or the like
- F02M27/08—Apparatus for treating combustion-air, fuel, or fuel-air mixture, by catalysts, electric means, magnetism, rays, sound waves, or the like by sonic or ultrasonic waves
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/30—Use of alternative fuels, e.g. biofuels
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Fuel-Injection Apparatus (AREA)
Abstract
Multi-component fuel is fractioned inside a cylindrical fuel reservoir 10 by means of an ultrasonic transducer 22 which creates a high energy acoustic field within the fuel exceeding the cavitation threshold of the lower boiling point fraction of the fuel, thus causing only that fraction to form cavitation bubbles. A coaxial centrifugal flow field is induced near the transducer 22, eg by the flow of returned fuel from the tangential return pipe 20, causing the fuel to swirl and the cavitation bubbles to migrate toward the central region 24 where the bubbles later collapse back to liquid thus forming a central region containing a relatively richer concentration of the lower boiling point fuel fraction. The fuel pump 12 draws a surplus-to-demand stream of fuel from the central region of the reservoir 10 via suction pipe 26 and supplies the fuel injectors 16 with fuel enriched in lower boiling-point fractions. As enriched surplus fuel is continually being returned and is fractioned again by the transducer, the enriched concentration of the lower boiling point fuel fraction builds up incrementally.
Description
MULTI-PASS FUEL SEPARATION AND INJECTION SYSTEM
Field of the invention
The present invention relates to a method and a system for supplying an internal combustion engine at times with a component-fractioned fuel derived from a multi-component fuel blend.
Background of the invention
It is well known that gasoline is a multi-component fuel with an average set of properties tailored to satisfy a broad range of engine operating conditions including good volatility for cold start, easy ignition with lean mixtures at low loads, high knock tolerance at high loads, and at the same time, free from problems such as vapour lock and deposits. Many of these are conflicting requirements and a compromise must be found in blending the properties of the So fuel in order to provide adequate performance all round with no significant defect in any one aspect, but no outstanding characteristic either.
A corollary of the above is that different fuel groups 2s have been selected intentionally to make up the commercial fuel blend based on the unique properties of each fuel group being better suited for a particular operating condition among a wider range of operating conditions. For example, the paraffin group is more volatile and more ignitable, Jo while the aromatic group has higher knock tolerance, these being mixed to produce the averaged general properties of the blend. Thus for a given multi-component fuel, instead of using it directly, it would be more advantageous to separate it again into its component groups before supplying it to the engine, using a higher proportion of one group in preference to another according to operating conditions. In this way the distinct properties of each fuel group may be - 2 - utilised in a more targeted manner, thus extending the operating boundaries of the engine in many aspects while overall still using the standard commercial fuel blend.
In one example, a higher concentration of the lower boiling point fuel fraction may be used during engine cold start, warm up, idle and light load operating conditions, in order to reduce exhaust emissions, improve drive quality and increase vehicle fuel economy. In another example, the lower boiling point fuel fraction, which has a higher hydrogen/carbon ratio than the original fuel blend, may be used advantageously for fuelling the engine during cold start with a sufficiently rich fuel-air mixture in order to produce in the exhaust gas a more hydrogen-augmented ignitable mixture for burning in an afterburner for rapidly heating a catalytic convertor in the engine exhaust system to its light-off temperature by the method of exhaust gas ignition (EGI) described in US 5425233.
so Conventional fuel separation systems rely on fractional distillation of the fuel by heating the fuel and condensing the vaporised fraction. For use on board a vehicle, in order to cope with a wide range of variable fuel demand from the engine, known systems have been designed either as a batch system in which the separated fuel components are produced in batches and stored in separate fuel tanks as described in GB 2209796, or as a continuous supply = demand equilibrium flow system in which the production flow rate of the separated fuel components is variable in response to the demand flow rate from the engine as described in GB 2330179.
Other systems, such as that described in US 4220120, aim to extract fuel vapour from the fuel tank to support a limited number of cold starts but ignores the consequence that the fuel in the tank would eventually be depleted of the light fractions resulting in poorer and poorer starts as the tank fuel is progressively being used up. All these systems suffer many disadvantages in that they are complicated and - 3 - costly, and are prone to instability and surges due to the time delay inherent in the fractional distillation process, making it unsuitable for use as stable fuel sources to meet all the transient demands from the engine requiring accurate fuel metering.
In order to mitigate at least some of the above- mentioned problems, GB 2361746 describes a fuel separation and injection system comprising means for drawing a fuel lo stream from a fuel reservoir, means for separating the fuel stream into at least two flow streams containing different fuel components having different fuel properties, means for connecting the separated flow streams to respective separate fuel rails arranged in parallel with one another with at least one fuel rail supplying at least one fuel injector, means for combining the unused flow streams from the separate fuel rails back into a single fuel stream, and means for returning the recombined fuel stream to the fuel reservoir. This system has the advantage that the fuel fractioning and separation processes are steady flow processes which take place always at the maximum constant flow rate which is the rated flow of the fuel pump, but the separated flow streams are not wholly used by the engine nor the surplus stored in separate fuel tanks. Instead, the unused surplus flow streams are recombined and returned to the fuel reservoir to be re-fractioned and re-separated again, along with some fresh fuel, so that the fuel fractioning and separation processes will proceed always at the same maximum rate and remain steady regardless of how so much or how little of the separated flow streams are actually dispensed by the fuel injector to the engine. This allows instantaneous demand of the separated fuel fractions from the respective separate fuel rails with no transient delay, hysteresis or surge as long as the demand flow does not exceed the rated flow of the pump. - 4
GB 2361746 described above however has several disadvantages in respect to the position of the fuel pump.
If a single fuel pump is positioned upstream of the fuel fractioning section, the fuel fractioning process could be s seriously suppressed by the high delivery pressure of the pump and a lot of energy is required to sustain the fractioning process. On the other hand, if two fuel pumps are positioned downstream of the fuel fractioning section each delivering one of the two separated flow streams to 0 separate fuel rails, then although the fuel fractioning process takes place at the suction pressure of the pump requiring much less energy, the two fuel pumps could cause cross-dilution of flows unless the separated flow streams are produced in equal quantities which is difficult to achieve.
Summary of the invention
In order to mitigate at least some of the disadvantages of GB 2361746 while retaining the advantages and introducing further improvements, there is provided according to a first aspect of the present invention a method for operating a fuel separation and injection system for an internal combustion engine, the method comprising the steps of drawing a surplus-to-demand component-fractioned fuel stream from a fuel reservoir of the said fuel separation and injection system topped up as necessary with a multi- component fuel from a main fuel tank, delivering the component-fractioned fuel stream at an elevated fuel pressure to a fuel rail supplying at least one fuel injector for dispensing the said component-fractioned fuel to be used in the engine, and returning the unused surplus component- fractioned fuel stream from the fuel rail back to the fuel reservoir thus completing a closed-loop for the surplus component-fractioned fuel, and further comprising the steps of fractioning and separating within the fuel reservoir at least the said returned surplus component-fractioned fuel into an incrementally more concentrated set of fuel fraction distribution radially across the fuel reservoir containing progressively different concentrations of fuel fraction components having different boiling properties, and drawing from the fuel reservoir for delivery to the fuel rail the incrementally more concentrated component-fractioned fuel stream from the central region of the radially distributed fuel fractions, thus compounding through multi-passes of the return fuel the concentration gradient of the fuel fraction lo distribution within the fuel reservoir each time the surplus fuel completes the said closed-loop and producing an increasing concentration of the said component- fractioned fuel stream drawn from the fuel reservoir for delivery to the said fuel rail.
According to a second aspect of the present invention, there is provided a fuel separation and injection system for an internal combustion engine, the system comprising flow suction means for drawing a surplus-to-demand component fractioned fuel stream from a fuel reservoir of the said fuel separation and injection system topped up as necessary with a multicomponent fuel from a main fuel tank, pumping means for delivering the component-fractioned fuel stream at an elevated fuel pressure to a fuel rail supplying at least one fuel injector for dispensing the said component- fractioned fuel to be used in the engine, and flow regulator means for returning the unused surplus component-fractioned fuel stream from the fuel rail back to the fuel reservoir thus completing a closed-loop for the surplus component fractioned fuel, and further comprising energising means for fractioning and separating within the fuel reservoir at least the said returned surplus component-fractioned fuel into an incrementally more concentrated set of fuel fraction distribution radially across the fuel reservoir containing progressively different concentrations of fuel fraction components having different boiling properties, and said flow suction means for drawing from the fuel reservoir for - 6 delivery to the fuel rail the incrementally more concentrated component-fractioned fuel stream from the central region of the radially distributed fuel fractions, thus compounding through multi-passes of the return fuel the concentration gradient of the fuel fraction distribution within the fuel reservoir each time the surplus fuel completes the said closed-loop and producing an increasing concentration of the said component-fractioned fuel stream drawn from the fuel reservoir for delivery to the said fuel lo rail.
In the invention, the fuel fractioning and separating section of the system is contained in the fuel reservoir of a conventional fuel injection system so that the closed-loop of fractioned surplus fuel returned to the fuel reservoir also constitutes a closed-loop returning the fuel to the fuel fractioning and separating section, thus enabling the return fuel to be fractioned again and again in multi-passes each time the surplus fuel completes the closed-loop and thereby producing more and more pronounced concentrations across the distribution of fuel fractions within the fuel reservoir. This compounding effect makes it possible to achieve very quickly a high concentration of the component- fractioned fuel stream drawn from the fuel reservoir for delivery to the fuel rail, without relying on a high energy fuel fractioning and separating system.
Preferably, the fuel reservoir is cylindrical in shape and the energising means for fractioning and separating the returned fuel within the fuel reservoir comprises cavitation means for inducing cavitation bubbles in the fuel, and centrifugal separating means for causing the fuel to swirl and the cavitation bubbles to migrate towards the central region of the centrifugal field concentric with the cylindrical axis of the fuel reservoir. - 7 -
Preferably, the cavitation means comprises an ultrasonic transducer vibrating within the fuel creating a high energy acoustic field exceeding the cavitation threshold of the lower boiling point fraction of the fuel.
Preferably, the centrifugal separating means comprises a fuel pump for drawing the surplus-to-demand component- fractioned fuel stream from the fuel reservoir for delivery to the fuel rail, and a pressure regulator for returning the lo unused surplus component-fractioned fuel stream from the fuel rail back to the fuel reservoir, characterized in that the surplus-to-demand fuel stream is drawn axially from the central region of the fuel reservoir and the surplus fuel stream is returned tangentially to the peripheral region of the fuel reservoir near the fuel fractioning section thereby creating a strong centrifugal flow field in the vicinity of the fuel fractioning section and concentric with the cylindrical axis of the fuel reservoir.
Apart from the above novel feature of compounding through multi-passes the fuel fraction concentration, the present invention is also an improvement over GB 2361746 in that a single fuel pump is sufficient positioned downstream of the fuel fractioning section so that the fuel fractioning process takes place at the suction pressure of the pump requiring less energy, while the pump delivers only one fuel stream at elevated pressure to only one fuel rail. This simplification would however restrict the use of the present fuel separation and injection system to supplying only one fuel fraction (the lower boiling fuel fraction) which has fuel properties advantageous for use during cold start, warm up, idle and light load operating conditions.
Unlike GB 2361746, the conjugate fraction of the component-fractioned fuel (the higher boiling point fuel fraction) is retained in the fuel reservoir and not circulated through a separate fuel rail for selective use by - 8 the engine. Instead, this heavier fuel fraction is concentrated progressively into the peripheral region of the fuel reservoir by the compounding multi-pass effect of the present invention, and not drawn out and later re-combined and mixed in a return flow with the lighter fraction to start the fuel fractioning process all over again in single passes each time from the bottom baseline resulting in only one incremental step in the fuel fractioning, as was the case in GB 2361746.
The above higher boiling point fuel fraction will nevertheless be used up by the engine through the same fuel rail for the lower boiling point fuel fraction after the latter has been depleted and the residual fuel in the fuel reservoir can no longer be fractioned. Thus the present invention still allows all the fractions of the fuel to be consumed, but in sequence of using up the lower boiling point fuel fraction first followed by the higher boiling point fuel fraction. Of course the same system of the present invention could be used to supply un-fractioned fuel by switching off the energising means when the component- fractioned fuel is not required.
In an additional arrangement, the higher boiling point fuel fraction concentrated near the peripheral region of the fuel reservoir may be tapped off by another fuel pump to another fuel rail supplying another set of fuel injectors and the surplus fuel returned through another fuel pressure regulator back to the same peripheral region remote from the fuel fractioning section in the fuel reservoir. In this case, it is possible to introduce selective use of either the lower boiling point fuel fraction or the higher boiling point fuel fraction in the engine, but the higher boiling point fuel fraction circulation loop plays no part in the multi-pass fuel separation system of the present invention (except for assisting the swirl) and merely takes advantage - 9 - of the fuel fraction distribution already established within the fuel reservoir.
The present invention retains the advantage of GB 2361746 in that the fuel fractioning process is a steady flow process and always takes place at the maximum constant flow rate which is the rated flow of the fuel pump. This allows instantaneous demand of the component- fractioned fuel from the fuel rail with no transient delay, hysteresis or lo surge as long as the demand flow does not exceed the rated flow of the pump.
The present invention may be used to supply a vehicle engine with a higher concentration of lower boiling point fuel fraction during cold start, warm up, idle and light load operating conditions in order to reduce exhaust emissions, improve drive quality and increase vehicle fuel economy. The lower boiling point fuel fraction is drawn only from the fuel reservoir of the fuel separation and injection system and does not depreciate in any way the fuel quality of the original fuel blend in the vehicle main fuel tank. In the case where an additional fuel injection circulation loop for the higher boiling point fuel fraction is included in the system, this fuel fraction may be used at times during acceleration and high load operating conditions in order to increase the knock tolerance and improve engine power output. In another application, the lower boiling point fuel fraction and the higher boiling point fuel fraction may be introduced simultaneously into different regions inside the combustion chamber of an engine in order to create a stratified charge with controlled variation within the charge according to fuel composition as well as fuel concentration.
When the fuel separation system of the present invention is not in use, the same fuel injection system comprising the fuel pump, fuel rail, fuel injectors and fuel - 10 pressure regulator may be operated in the conventional manner with the surplus-to-demand fuel stream drawn from the main fuel tank and the surplus fuel returned to the main fuel tank. In this case, a bypass valve may be included to divert the surplus fuel to return directly to the main fuel tank.
Brief description of the drawing
lo The invention will now be described further, by way of example, with reference to the accompanying drawings in which: Figure 1 is a schematic view of a preferred embodiment of a fuel separation and injection system of the invention, and Figure 2 is a schematic view of an additional fuel injection circulation loop included in the fuel separation and injection system of Figure 1.
Detailed description of the preferred embodiment
In Figure 1, fractioning of a multi-component fuel is achieved within the fuel reservoir 10 by means of an ultrasonic transducer 22 which creates a high energy acoustic field within the fuel exceeding the cavitation threshold of the lower boiling point fraction of the fuel, thus causing only that part of the fuel to form cavitation bubbles.
The shape of the fuel reservoir 10 is cylindrical and the ultrasonic transducer 22 is positioned near the bottom of the fuel reservoir 10 concentric with the cylindrical axis of the fuel reservoir 10. A centrifugal flow field also concentric with the cylindrical axis is induced in the vicinity of the ultrasonic transducer 22 and this causes the fuel to swirl and the cavitation bubbles to migrate towards the central region 24 of the centrifugal field where the - 11 bubbles later collapse back to liquid thus forming a component-fractioned region near the centre of the fuel reservoir 10 containing a relatively richer concentration of the lower boiling point fuel fraction.
To create the centrifugal flow field, a fuel pump 12 draws a surplus-todemand stream of the component-fractioned fuel from a suction pipe 26 axially from the central region 24 of the fuel reservoir 10 and delivers it at a regulated lo fuel pressure to a fuel rail 14 supplying a set of fuel injectors 16. A fuel pressure regulator 18 sets the fuel rail pressure and returns the surplus component-fractioned fuel via a return pipe 20 tangentially back to the peripheral region of the fuel reservoir 10 near the IS ultrasonic transducer 22, thus creating a strong centrifugal flow field in the vicinity of the fuel fractioning section 24 concentric with the cylindrical axis of the fuel reservoir 10.
The fuel injectors 16 dispense fuel for use in the engine and this fuel is the component-fractioned fuel containing a relatively richer concentration of the lower boiling point fuel fraction. As the fuel pump 12 circulates this fuel around a close-loop designated by 24, 26, 12, 14, 2s 18, 20, 24, any fuel dispensed by the fuel injectors 16 will be replaced by introducing top-up fuel drawn from a main fuel tank 30. The top-up fuel will be fresh fuel containing the original multi-component fuel blend and this is arranged to enter tangentially via a pipe 32 into the peripheral region of the fuel reservoir 10 in the same swirling direction as the return surplus fuel thus assisting the centrifugal flow field. In Figure 1, although the pipe 32 is shown above the pipe 20 for clarity, it could preferably be positioned in the same plane as the pipe 20 so that both 3s the top-up fuel and the return surplus fuel arrive in close vicinity of the ultrasonic transducer 22. - 12
In so far described, because the ultrasonic transducer 22 induces a high energy acoustic field in the original fuel blend containing as much higher boiling point fuel fraction as the lower boiling point fuel fraction, a relatively large proportion of the energy will be absorbed by the higher boiling point fuel fraction and less energy transferred to the lower boiling point fuel fraction resulting in a relatively small enrichment of the lower boiling point fuel fraction at the central region 24 of the fuel fractioning lo section. However, as the enriched surplus fuel is continuously being returned tangentially to the ultrasonic transducer 22 and fractioned again and again through multi- passes, with each pass picking up an incrementally more enriched fuel drawn from the central region 24 of the fuel fractioning section, more and more energy will be transferred to an increasing proportion of the lower boiling point fuel fraction in the fuel and a cumulative effect will soon build up by positive feedback where the enriched concentration of the lower boiling point fuel fraction delivered to the fuel rail 14 increases rapidly to a sufficiently high level to show a recognizable change in the fuel properties dispensed to the engine. Correspondingly the energy output by the ultrasonic transducer 22 may need to be increased progressively as the concentration of the lower boiling point fuel fraction in the componentfractioned fuel increases so that sufficient energy is available to cause substantially all of the said lower boiling point fuel fraction to form cavitation bubbles.
Parallel to the above, the conjugate fraction of the fuel (the higher boiling point fuel fraction) will progressively accumulate with increasing concentration in the upper peripheral regions 28 of the fuel reservoir 10.
This will remain in the reservoir until most of the lower boiling point fuel fraction contained in the fuel reservoir has been depleted through the fuel injectors 16 and the residual fuel remaining in the reservoir can no longer be - 13 fractioned by the ultrasonic transducer 22. This residual fuel will then be circulated through the same fuel rail 14 and dispensed by the fuel injectors 16 to the engine so that all the fractions of the original fuel blend will eventually be consumed by the engine. During this time, the ultrasonic transducer 22 may be switched off and the fuel in the fuel reservoir 10 will be gradually replaced with fresh fuel from the main fuel tank 30 until finally the fuel dispensed by the fuel injectors 16 is the original un-fractioned fuel lo blend.
The above sequence of events will be ideal for exploiting the beneficial properties of the lower boiling point fuel fraction in a vehicle engine during cold start, warm up, idle and light load operating conditions, in order to reduce exhaust emissions, improve drive quality and increase vehicle fuel economy during the early part of a driving trip. This lower boiling point fuel fraction drawn from the fuel reservoir 10 is used earlier than the higher boiling point fuel fraction, but the sequential use of both fractions drawn only from the fuel reservoir 10 does not depreciate in any way the fuel quality of the original fuel blend in the vehicle main fuel tank 30. At the end of the sequence, with the ultrasonic transducer 22 switched off, a bypass valve 34 may be activated to divert the surplus un- fractioned fuel to return directly to the main fuel tank 30 along the pipe 36.
The fuel separation system of Figure 1 is therefore essentially a semibatch system in which a substantially fixed quantity of the lower boiling point fuel fraction in the original fuel blend initially contained within the designed volume of the fuel reservoir 10 is extracted as a batch for use during starting and warm up of the engine.
This fixed quantity, and the associated volume of the original fuel blend in the fuel reservoir 10, must therefore be chosen to be sufficient to last the expected demand - 14 period of the engine, followed by the conjugate higher boiling point fuel fraction also being used up before the fuel reservoir 10 is filled again with a fresh batch of the original fuel blend.
The fuel separation system of Figure 1 may also be used as a continuous flow system by introducing, as shown in Figure 2, an additional fuel injection circulation loop 28, 56, 42, 44, 48, 50, 28. In this loop, the higher boiling lo point fuel fraction concentrated near the upper peripheral region 28 of the fuel reservoir 10 is tapped off tangentially by a pipe 56, drawn by another fuel pump 42 and delivered to another fuel rail 44 supplying another set of fuel injectors 46, and the surplus fuel returned through IS another fuel pressure regulator 48 tangentially along a pipe back to the same upper peripheral region 28 remote from the fuel fractioning section 24 in the fuel reservoir 10.
This allows selective use of the lower boiling point fuel fraction and the higher boiling point fuel fraction So alternately or simultaneously in the engine, but the higher boiling point fuel fraction circulation loop plays no part in the multi-pass fuel separation system of Figure 1 (except for assisting the swirl) and merely takes advantage of the fuel fraction distribution already established within the Is fuel reservoir 10. In this case, by providing the additional fuel injection circulation loop for the higher boiling point fuel fraction, this fuel fraction may be used at times during acceleration and high load operating conditions in order to increase the knock tolerance and improve engine power output. In another application, the lower boiling point fuel fraction and the higher boiling point fuel fraction may be introduced simultaneously into different regions inside the combustion chamber of an engine in order to create a stratified charge with controlled variation within the charge according to fuel composition as well as fuel concentration.
The fuel separation and injection system of Figure 1 uses many standard components found in most conventional fuel injection systems, with the addition of the fuel reservoir 10, the ultrasonic transducer 22 and the bypass valve 34. The system has the advantage that the fuel fractioning process is a steady flow process and always takes place at the maximum constant flow rate which is the rated flow of the fuel pump 12. This allows instantaneous demand of the component-fractioned fuel from the fuel rail lo 14 with no transient delay, hysteresis or surge as long as the demand flow does not exceed the rated flow of the pump 12.
The component-fractioned fuel supply may be activated or deactivated at any time by switching on or off the ultrasonic transducer 22 as required. In a special case, for a short time period after the engine is stopped, the fuel pump 12 may be kept running and the ultrasonic transducer 22 is switched on for long enough to produce sufficient quantity of the lower boiling point fuel fraction to be stored in the fuel rail 14, so that this stored fuel is immediately available for use in the engine when the engine is started again at a later time. This stored fuel, with a higher hydrogen/carbon ratio than the original fuel blend, is also suitable for fuelling the engine during cold start with a sufficiently rich fuel-air mixture in order to produce in the exhaust gas a more hydrogen-augmented ignitable mixture for burning in an afterburner for rapidly heating a catalytic convertor in the engine exhaust system to its light-off temperature by the method of exhaust gas ignition (EGI) described in US 5425233. - 16
Claims (1)
1. A method for operating a fuel separation and injection system for an internal combustion engine, the method comprising the steps of drawing a surplus-to-demand component-fractioned fuel stream from a fuel reservoir of the said fuel separation and injection system topped up as necessary with a multi-component fuel from a main fuel tank, delivering the component-fractioned fuel stream at an lo elevated fuel pressure to a fuel rail supplying at least one fuel injector for dispensing the said component-fractioned fuel to be used in the engine, and returning the unused surplus component-fractioned fuel stream from the fuel rail back to the fuel reservoir thus completing a closed-loop for the surplus component-fractioned fuel, and further comprising the steps of fractioning and separating within the fuel reservoir at least the said returned surplus component-fractioned fuel into an incrementally more concentrated set of fuel fraction distribution radially JO across the fuel reservoir containing progressively different concentrations of fuel fraction components having different boiling properties, and drawing from the fuel reservoir for delivery to the fuel rail the incrementally more concentrated component-fractioned fuel stream from the central region of the radially distributed fuel fractions, thus compounding through multipasses of the return fuel the concentration gradient of the fuel fraction distribution within the fuel reservoir each time the surplus fuel completes the said closed-loop and producing an increasing concentration of the said component-fractioned fuel stream drawn from the fuel reservoir for delivery to the said fuel rail.
2. A fuel separation and injection system for an internal combustion engine, the system comprising flow suction means for drawing a surplus-to-demand component- fractioned fuel stream from a fuel reservoir of the said - 17 fuel separation and injection system topped up as necessary with a multi- component fuel from a main fuel tank, pumping means for delivering the component-fractioned fuel stream at an elevated fuel pressure to a fuel rail supplying at least one fuel injector for dispensing the said component- fractioned fuel to be used in the engine, and flow regulator means for returning the unused surplus component-fractioned fuel stream from the fuel rail back to the fuel reservoir thus completing a closed-loop for the surplus component lo fractioned fuel, and further comprising energizing means for fractioning and separating within the fuel reservoir at least the said returned surplus component-fractioned fuel into an incrementally more concentrated set of fuel fraction distribution radially across the fuel reservoir containing progressively different concentrations of fuel fraction components having different boiling properties, and said flow suction means for drawing from the fuel reservoir for delivery to the fuel rail the incrementally more concentrated component-fractioned fuel stream from the central region of the radially distributed fuel fractions, thus compounding through multi- passes of the return fuel the concentration gradient of the fuel fraction distribution within the fuel reservoir each time the surplus fuel completes the said closed-loop and producing an increasing concentration of the said component-fractioned fuel stream drawn from the fuel reservoir for delivery to the said fuel rail.
3. A fuel separation and injection system as claimed in claim 2, wherein the fuel fractioning and separating section of the system is contained in the fuel reservoir so that the closed-loop of fractioned surplus fuel returned to the fuel reservoir also constitutes a closed-loop returning the fuel to the fuel fractioning and separating section, thus enabling the return fuel to be fractioned again and again in multi-passes each time the surplus fuel completes the closed-loop and thereby producing more and more - 18 pronounced concentrations across the distribution of fuel fractions within the fuel reservoir.
4. A fuel separation and injection system as claimed in claim 2 or 3, wherein the fuel reservoir is cylindrical in shape and the energising means for fractioning and separating the returned component-fractioned fuel within the fuel reservoir comprises cavitation means for inducing cavitation bubbles in the fuel, and centrifugal separating lo means for causing the fuel to swirl and the cavitation bubbles to migrate towards the central region of the centrifugal field concentric with the cylindrical axis of the fuel reservoir.
5. A fuel separation and injection system as claimed in claim 4, wherein the cavitation means comprises an ultrasonic transducer vibrating within the fuel creating a high energy acoustic field exceeding the cavitation threshold of the lower boiling point fraction of the fuel.
7. A fuel separation and injection system as claimed in claim 4 and 5, wherein the energy output by the ultrasonic transducer is increased as the concentration of the lower boiling point fuel fraction in the component fractioned fuel increases so that sufficient energy is available to cause substantially all of the said lower boiling point fuel fraction to form cavitation bubbles.
8. A fuel separation and injection system as claimed in claim 4, wherein the centrifugal separating means comprises a fuel pump for drawing the surplus-to-demand component-fractioned fuel stream from the fuel reservoir for delivery to the fuel rail, and a pressure regulator for returning the unused surplus component-fractioned fuel stream from the fuel rail back to the fuel reservoir, characterized in that the surplus- to-demand fuel stream is drawn axially from the central region of the fuel reservoir - 19 and the surplus fuel stream is returned tangentially to the peripheral region of the fuel reservoir near the fuel fractioning section thereby creating a strong centrifugal flow field in the vicinity of the fuel fractioning section and concentric with the cylindrical axis of the fuel reservoir.
9. A fuel separation and injection system as claimed in any preceding claim, wherein the conjugate fraction of lo the fuel concentrated near the peripheral region of the fuel reservoir is tapped off by another fuel pump to another fuel rail supplying another set of fuel injectors and the surplus fuel returned through another fuel flow regulator back to the same periphery region remote from the fuel fractioning section in the fuel reservoir.
10. A fuel separation and injection system as claimed in any preceding claim, wherein when the fuel separation system is not in use and after the separated fuel in the JO fuel reservoir is completely used up by the engine, the same fuel injection system comprising the fuel pump, fuel rail, fuel injectors and flow regulator are operated in the conventional manner with the surplus-to-demand fuel stream drawn through the fuel reservoir from the main fuel tank and the surplus fuel returned directly to the main fuel tank.
11. A fuel separation and injection system as claimed in claim 10, wherein the volume of the fuel reservoir, when it is filled with the original fuel blend drawn from the main fuel tank, is such that when the fuel separation system is activated again during a subsequent cold start of the engine, the associated quantity of the lower boiling point fuel fraction separated out from the said original fuel blend contained in the fuel reservoir is sufficient to meet the fuel demand from the engine at least during the cold start and the early warm up period of the engine. -
12. A fuel separation and injection system as claimed in any preceding claim, wherein for a short time period after the engine is stopped, the fuel pump is kept running and the ultrasonic transducer is switched on for long enough to produce sufficient quantity of the lower boiling point fuel fraction to be stored in the fuel rail, so that this stored fuel is immediately available for use in the engine when the engine is started again at a later time.
lo 13. A fuel separation and injection system as claimed in claim 12, wherein when the engine is started again from cold, the said lower boiling point fuel fraction stored in the fuel rail is used for fuelling the engine with a sufficiently rich fuel-air mixture in order to produce in the exhaust gas an ignitable hydrogen-containing mixture for burning in an afterburner for rapidly heating a catalytic convertor in the engine exhaust system to its light-off temperature.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GBGB0306118.1A GB0306118D0 (en) | 2003-03-18 | 2003-03-18 | Multi-pass fuel separation and injection system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB0306902D0 GB0306902D0 (en) | 2003-04-30 |
| GB2399598A true GB2399598A (en) | 2004-09-22 |
Family
ID=9954957
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GBGB0306118.1A Ceased GB0306118D0 (en) | 2003-03-18 | 2003-03-18 | Multi-pass fuel separation and injection system |
| GB0306902A Withdrawn GB2399598A (en) | 2003-03-18 | 2003-03-26 | Multi-pass fuel separation and injection system for i.c. engines |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GBGB0306118.1A Ceased GB0306118D0 (en) | 2003-03-18 | 2003-03-18 | Multi-pass fuel separation and injection system |
Country Status (1)
| Country | Link |
|---|---|
| GB (2) | GB0306118D0 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2682933C1 (en) * | 2018-02-05 | 2019-03-22 | федеральное государственное бюджетное образовательное учреждение высшего образования "Пензенский государственный аграрный университет" | Auto tractor diesel engine dual fuel supply system |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2084681C1 (en) * | 1994-09-28 | 1997-07-20 | Алексей Викторович Афанасьев | Cavitation generator |
| RU2120562C1 (en) * | 1996-10-08 | 1998-10-20 | Михаил Ионович Браславский | Method of processing of heavy fuel before injection into combustion chamber of internal combustion engine or boiler and system for preparation of fuel for multifuel diesel engine |
| GB2361746A (en) * | 2000-04-25 | 2001-10-31 | Jonathan Austin Ma | Fuel injection system for supplying to an i.c. engine fuel divided into separate components |
-
2003
- 2003-03-18 GB GBGB0306118.1A patent/GB0306118D0/en not_active Ceased
- 2003-03-26 GB GB0306902A patent/GB2399598A/en not_active Withdrawn
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2084681C1 (en) * | 1994-09-28 | 1997-07-20 | Алексей Викторович Афанасьев | Cavitation generator |
| RU2120562C1 (en) * | 1996-10-08 | 1998-10-20 | Михаил Ионович Браславский | Method of processing of heavy fuel before injection into combustion chamber of internal combustion engine or boiler and system for preparation of fuel for multifuel diesel engine |
| GB2361746A (en) * | 2000-04-25 | 2001-10-31 | Jonathan Austin Ma | Fuel injection system for supplying to an i.c. engine fuel divided into separate components |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2682933C1 (en) * | 2018-02-05 | 2019-03-22 | федеральное государственное бюджетное образовательное учреждение высшего образования "Пензенский государственный аграрный университет" | Auto tractor diesel engine dual fuel supply system |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0306902D0 (en) | 2003-04-30 |
| GB0306118D0 (en) | 2003-04-23 |
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| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |