WO2018142097A1 - Perfectionnements apportés au fonctionnement de moteurs - Google Patents

Perfectionnements apportés au fonctionnement de moteurs Download PDF

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Publication number
WO2018142097A1
WO2018142097A1 PCT/GB2018/000016 GB2018000016W WO2018142097A1 WO 2018142097 A1 WO2018142097 A1 WO 2018142097A1 GB 2018000016 W GB2018000016 W GB 2018000016W WO 2018142097 A1 WO2018142097 A1 WO 2018142097A1
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WIPO (PCT)
Prior art keywords
piston
engine
combustion
cylinder
movement
Prior art date
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PCT/GB2018/000016
Other languages
English (en)
Inventor
Peter Martin
Original Assignee
Combustion Order Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Combustion Order Ltd filed Critical Combustion Order Ltd
Publication of WO2018142097A1 publication Critical patent/WO2018142097A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B75/00—Other engines
    • F02B75/32—Engines characterised by connections between pistons and main shafts and not specific to preceding main groups
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D15/00—Varying compression ratio
    • F02D15/02—Varying compression ratio by alteration or displacement of piston stroke
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B75/00—Other engines
    • F02B75/04—Engines with variable distances between pistons at top dead-centre positions and cylinder heads
    • 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
    • F02D19/10—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 peculiar to compression-ignition engines in which the main fuel is gaseous
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B2275/00—Other engines, components or details, not provided for in other groups of this subclass
    • F02B2275/36—Modified dwell of piston in TDC
    • 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

Definitions

  • the present invention relates to improvements in the method of operation of internal combustion engines in order to achieve improved performance, fuel efficiency and exhaust emissions.
  • Combustion is the burning of a fuel compound in air. Combustion is initiated by free radicals, normally produced by heating and aided by an increase in pressure. Combustion itself is characterised by chain branching reactions which generate further radicals. This can lead to rapid propagation of the chain branching reactions under favourable conditions, which is normally the desired result.
  • Combustion of hydrocarbon based fuel is at the heart of the internal combustion engine, of which the reciprocating engine is the dominant type by market volume.
  • the reciprocating engine has particular characteristics.
  • a piston moves in a sinusoidal mode inside an engine cylinder, connected at an offset position to a crankshaft by a connecting rod.
  • each up and down stroke of the piston is identical to the next, regardless of what stroke it is in the engine cycle, the down stoke typically being the power stroke and the upstroke the return or exhaust stroke in a 2-stroke engine.
  • the down stroke would correspond with either the power stroke or the intake stroke in a 4-stroke engine.
  • the piston undergoes a speed difference on the power stroke when the combustion of the fuel generates the expanding gasses which drive the piston down the cylinder bore and thus rotate the crank to generate rotational mechanical energy. Typically, this generates an acceleration of the crankshaft rotation even at steady state (constant rpm) conditions. Likewise, there could be speed differences, both positive and negative on the other strokes of the engine.
  • the gasoline (petrol) engine typically operates with a compression ratio of approximately 10:1 , uses spark ignition and requires a stoichiometric ratio of air to fuel ratio of 14:1 for optimal combustion. When ignition occurs, combustion occurs rapidly. This conforms to the Otto thermodynamic cycle.
  • the diesel engine typically operates with a compression ratio of 20:1 , uses compression ignition and is not strictly stoichiometric, being able to combust with much higher ratios of air. When ignition occurs, combustion progresses less rapidly. This conforms to the diesel thermodynamic cycle.
  • thermodynamic cycles are ideal and thus unlikely to be seen in the real world.
  • a hybrid cycle sometimes known as the Trinkler cycle which is a combination of both.
  • HCCI Homogenous Charge Compression Ignition
  • ARC Activated Radical Combustion
  • RCCI Reactivity Controlled Compression Ignition
  • the term primary fuel used above and hereinafter is referring to the fuel which is the majority component of the fuel supplied to the engine by molecular volume and whose combustion provides the main power for the engine.
  • Additives which have been demonstrated in the prior art to be effective with diesel engines include liquid petroleum gas (LPG), hydrogen and Nitrous Oxide.
  • the compression ignition engine operates with a pilot injection of primary fuel, which is employed to raise the in cylinder temperature and pressure to effectively activate the additive prior to the main injection of primary fuel.
  • the net effect is that combustion of the main injection of primary diesel fuel exhibits characteristics similar to those of gasoline (petrol). These include low ignition delay, fast combustion propagation and more complete combustion of the fuel. This results in lower particulate emissions (soot & unburnt fuel) and a significant reduction in the oxides of Nitrogen (NOX).
  • Gasoline (petrol) engines are generally less efficient that diesel engines due to the lower compression ratios. However, because gasoline combusts rapidly with low ignition delay (following spark ignition) they are well suited to high speed applications. Diesel cycle engines on the other hand can typically either be low or high speed.
  • An example of a low speed diesel engine is a marine diesel that uses heavy oil as a fuel. Typically, these operate by heating the fuel (to reduce viscosity) and with a maximum speed of a few hundred rpm.
  • An example of a high speed diesel engine is found in a passenger car engine. Typically, these operate on a single fuel (pump diesel) and have a maximum speed only slightly less than a gasoline (petrol) engine. Because of the combustion characteristics of the diesel fuel compared to gasoline these require exhaust after treatments to deal with particulates and NOX.
  • the standard reciprocating engine motion minimises the time that the gasses are constrained on the power stroke, due to the sinusoidal motion of the piston and the acceleration of the piston during the power stroke.
  • the piston speed within an internal combustion engine is never constant.
  • the piston will experience acceleration during the power (i.e. combustion) stroke (due to the generation and rapid expansion of the combustion gases) and deceleration on the other strokes, most noticeably on the compression stroke. Thus, it is only during the compression stroke where the engine is generating energy, during other times it is consuming energy.
  • the amount of energy generated will depend on the quantity of fuel and air supplied to the engine cylinder prior to combustion and the efficiency and speed of the combustion and the peak pressure achieved during combustion.
  • the energy consumed during the other cycles of the engine will depend on the amount of air in the engine, the pressure inside the engine cylinder and the pumping efficiency of the engine. This will be dependent on the design of the engine, but factors will include the compression ratio, the friction losses, the valve timings and any restrictions in the intake and exhaust systems.
  • the piston speed will also change dependent on the operational conditions of the engine.
  • the load applied to the engine will also affect the piston speed as this is the desired consumer of the energy output from the engine.
  • an engine design whereby the power stroke is of increased time duration, or is subject to a high load (thus slowing the rate of crankshaft rotation), compared to a standard reciprocating engine design, may address these drawbacks and generate longer periods of actual or pseudo constant volume combustion with the aim of improving combustion completeness and efficiency.
  • a change in piston speed i.e. reducing the rate of piston acceleration during all or part of the power stroke
  • the inventor has further realised that a concentration of free radicals generated immediately prior to the main combustion event can be maintained with combustion enhancement techniques, and that the only logical explanation for the efficacy of combustion enhancement is that it is related to a change in the free radical environment in the engine cylinder prior to the main combustion event.
  • a method of improving the efficiency of an internal combustion engine having a piston configured for reciprocating movement within a cylinder characterised by at least reducing the rate of movement of the piston along the cylinder with respect to the combustion chamber during at least a part of the first 90 degrees of each combustion stroke, the movement of the piston being reduced for a continuous period starting after the top dead centre of the piston within the cylinder and finishing not later than 90 degrees after top dead centre, and the reduction being applied each cycle of the engine such that the path of the piston during each cycle of the engine is cyclic but not completely sinusoidal for at least part of the first 90 degrees of the combustion stroke.
  • the movement of the piston with respect to the combustion chamber is retarded or arrested during the first 90 degrees of each combustion stroke, the restriction being applied to each cycle of the engine so that the piston still executes a periodic movement but the path is not sinusoidal for at least part of the first 90 degrees of the combustion stroke.
  • pseudo constant volume it is meant that the rate of increase of the volume of the combustion chamber is reduced as compared with a piston which is undergoing a normal combustion induced sinusoidal movement. Accordingly, the timing of the combustion is controlled in a manner which changes the combustion conditions so as to change the combustion characteristics by moving the combustion along the combustion spectrum rather than by changing the reactivity of the fuel.
  • the combustion of the diesel fuel is made to be more characteristic of petrol, so that the particulate and NOX emissions are reduced whilst maintaining the advantage of the higher fuel efficiency associated with diesel fuel, or the combustion of petrol fuel is shifted further to provide even less emissions, more power, or both.
  • the movement of the piston may be controlled during just a part of, or for the whole of the first 90 degrees of rotation of the crankshaft after TDC of the piston, but it is important that it controlled on every engine cycle.
  • the portion during which the movement of the piston is controlled or retarded may, though, be varied between cycles to achieve optimum engine performance at different engine speeds and loads.
  • the movement of the piston is completely stopped for at least part of the first 90 degrees of the combustion stroke so as to keep the volume of the combustion chamber constant for said at least part of the first 90 degrees of the combustion stroke.
  • the movement of the piston may be controlled by mechanical means. This may be by, for example, controlling the length of the rod which connects the piston to the crankshaft, using opposed pistons, dual crankshafts in the engine, a geared arrangement such as planetary gears for the connecting rod and crankshaft, a camming arrangement between the connecting rod and the crankshaft configured to reduce the rate of or even stop the movement of the piston during a period of the rotation of the crankshaft.
  • the motion of the piston need no longer be sinusoidal.
  • the connecting rod is of fixed length but acts on a cam rather than the crankshaft, such as the swash plate engine.
  • the piston movement can be non-sinusoidal, it is always cyclic and follows a repetitive cycle, although in some designs this can be varied over time.
  • the magnitude and shape of the excursion on the displacement (Y) axis can be customised in addition to changes along the time (X) axis. The purpose of this is generally to change the compression ratio of the engine.
  • the cylinder may be allowed to move in the direction of rotation of the crankshaft for the required portion of the combustion stroke or a part thereof so as to compensate for the rotation of the crankshaft and thereby reduce the relative movement of the piston in the cylinder or even stop it, the cylinder then being rotated back to its original position during at least a part of the remainder of the engine cycle.
  • the increase in peak cylinder pressure is the only energy storage mechanism.
  • the cylinder moving mechanism will require energy to operate it during each power stroke. This can be considered akin to an active engine mount.
  • a standard passive engine mount (traditionally rubber) is deflected when the crank shaft accelerates on the power stroke.
  • a standard engine arrangement is maintained with a fixed connecting rod with a single bearing at each end connecting to the piston and an offset position on the crankshaft respectively.
  • the purpose of the invention is intended to alter the sinusoidal characteristic of such a standard engine in the time domain only.
  • inducing constant or pseudo constant volume combustion conditions will elongate part of the sine wave (where it was previously compressed) on the time (X) axis for the power stroke.
  • applying stored energy to generate rotational force on the crankshaft could also be used to compress part of the sine wave (where it was previously elongated) on the time (X) axis for the compression stroke.
  • the invention does not change the compression ratio of the engine, or the valve timing.
  • the movement of the piston may be controlled by controlling the load on the engine which is transmitted to the piston back through the crankshaft.
  • this may be achieved by, for example, varying an electrical load as might be applied by an alternator, the power from which may be used to charge on-board batteries for powering an alternative drive means such as in a hybrid vehicle.
  • This approach has the advantage that it could be retro applied to existing engine designs by appropriate reprogramming of the engine management system rather than requiring a completely new design for implementation.
  • Such loading may be applied as one continuous load or may be applied in multiple bursts, the latter being more suitable for power generation or providing power for an electric drive system.
  • a variable load is applied to the engine that is synchronised with the rotational position of a reciprocating engine and the position in the engine cycle.
  • Measurement of cylinder pressure may also be used to control the application of the variable load to the engine in a closed loop control system.
  • a variable load may advantageously be applied after combustion of the primary fuel charge has started in a compression ignition engine.
  • Primary combustion occurs at different positions depending on the operational conditions (such as rpm), and the implementation, in some embodiments, may be better linked to the combustion event.
  • an electrical load is applied the crankshaft to slow the rate of increase of the combustion volume after ignition with the objective of inducing constant or pseudo constant volume combustion conditions, energy can additionally be stored as electrical charge. This could typically be in a capacitor or a battery.
  • a proportion of the energy employed to increase the combustion efficiency of the engine is available to be re-used as electrical energy.
  • Energy stored during the combustion stroke may be used to increase the rate of piston movement during the compression stroke.
  • this is the cycle where the piston decelerates most because of the work required to compress the air in the cylinder to raise the temperature and pressure to a point where auto ignition of the fuel will occur in a compression ignition engine. Therefore, to assist this movement using stored energy will reduce the piston speed fluctuations in the engine.
  • it makes it possible to make a smoother running single cylinder engine, thus reducing the need for multi cylinder engines in some applications. This is particularly advantageous when used in a motor/generator type implementation whereby the same electrical unit is used as a generator during the combustion stroke and as a motor during the compression stroke.
  • the stored energy may alternatively or additionally be used to increase the rate of piston movement during the exhaust stroke. This has the advantage of potentially improving emissions.
  • Both the start point and the end point of the retardation of the piston during the first 90 degrees after top dead centre may be varied depending on operating conditions. It is not necessary that the retardation starts at top dead centre nor that it stops at a fixed period or fixed angle after it starts. So, for example, the mechanical or load based retardation might start at 10 degrees after top dead centre and stop at 30 degrees at 2000 rpm, but might be applied from 15 degrees to 55 degrees at 4000 rpm. The exact requirements will be different for different engine designs and requirements.
  • a key feature of the method of the first aspect of the invention is that energy is not wasted, as it is effectively stored up in the combustion chamber in the form or increased pressure during the combustion, which, when the retardation is released, will result in faster acceleration of the piston and therefore greater torque delivered to the crankshaft for the same fuel consumption.
  • the retardation is released at 90 degrees so as to provide the maximum moment arm on the crankshaft and hence the maximum torque.
  • energy can also be recovered through the load applying means, such as by storing as electrical energy as set out above.
  • Combustion enhancement according to this first aspect of the invention produces faster, or more intense combustion, both in terms of auto ignition delay and combustion propagation.
  • the net effect is that for the same ignition timing the combustion event is advanced in time. This corresponds with either a smaller cylinder volume, or a lower rate of increase of cylinder volume, or both, because of the position of the piston relative to TDC. This results in higher engine cylinder pressure and temperature being achieved.
  • the piston has an increased resistance to movement, which slows the increase in cylinder volume, as the turning moment on the crankshaft is reduced the closer the piston is to TDC in a reciprocating engine.
  • the movement of the piston relative to a fixed engine cylinder is sinusoidal. This results in sinusoidal variation in the effective volume of the combustion chamber.
  • the method according to the invention enables this sinusoid movement to be modified to, for example, a flat topped sinusoid relationship (X direction change) or a gapped sinusoid relationship (Y direction change), or a combination of both.
  • the method employed to slow the rate of increase of the combustion volume after ignition, with the objective of inducing constant or pseudo constant volume combustion conditions must be variable and individually controlled for each engine cycle. This ensures that optimum combustion conditions are achieved for each engine cycle regardless of the operational state of the engine.
  • the constant or pseudo constant volume combustion conditions change the nature of the combustion by moving it along the combustion spectrum. This shift from deflagration towards detonation produces faster, more complete combustion that generates a different emission profile.
  • a necessary characteristic of constant or pseudo constant volume combustion conditions is increased peak cylinder pressure during the power stroke. This is achieved for each individual engine cycle using a variable mechanism.
  • a closed loop system to implement the control for this would preferably use cylinder pressure as the feedback signal.
  • An open loop system would preferably use the operating conditions of the engine to predict the requirement for the next engine cycle based on the current cycle.
  • a preferred system would most likely use elements of both to provide redundancy and fail safe operation.
  • a method of enhancing the combustion in a cylinder of an internal combustion engine comprising providing a primary hydrocarbon based fuel for igniting in the combustion chamber of an engine in order to drive a piston along a cylinder to provide drive to an engine, providing a secondary hydrocarbon based fuel into the combustion chamber, the LFL of the secondary fuel being higher than the LFL of the primary fuel, the concentration of the secondary fuel being less than or equal to its LFL relative to the amount of air in the cylinder, whereby during the combustion of the primary fuel, the temperature and pressure of the secondary fuel is increased such that the secondary fuel experiences chemical decomposition and generates free radicals.
  • a method in accordance with the further aspect of the invention has the advantage that, by selection of the secondary fuel to have a higher LFL than the primary fuel, the secondary fuel does not combust during an initial combustion of the primary fuel and instead has its temperature and pressure increased by the heat and vapour gas expansion resulting from the combustion of the primary fuel until it exceeds its auto ignition temperature, whereupon it will generate radicals and experience chemical decomposition, which is similar to the onset of combustion but without the rapid propagation, due to the low concentration of the secondary fuel (i.e. below the LFL).
  • the higher LFL of the secondary fuel ensures that the secondary fuel experiences the combustion of the primary fuel when the secondary fuel has exceeded its LFL and, therefore, no longer exhibits the normal rate of combustion.
  • the chemical decomposition of the secondary fuel will result in the generation of radicals which enhance the combustion of the primary fuel with the overall aim being to move the combustion along the combustion spectrum.
  • a pilot combustion of the primary fuel occurs prior to a main injection of the primary fuel, the secondary fuel being present in the combustion chamber during the pilot combustion such that it experiences the increased temperature and pressure resulting from the pilot combustion.
  • injection of the primary fuel into the combustion chamber is separated into a pilot injection and a main injection, the secondary fuel being injected prior to or during the pilot injection.
  • the purpose of the secondary fuel is to generate radicals which will enhance the combustion of the main injection of the primary fuel, so that the radicals must therefore persist in the short time between the pilot and main injections of the primary fuel.
  • the pilot injection of primary fuel should be of sufficient volume to combust normally. This is because the concentration will, by definition, be between the LFL and UFL limits for the primary fuel.
  • the combustion of the primary fuel will increase the temperature and pressure in the engine cylinder. This is in addition to the increase in pressure and temperature in the engine cylinder generated by the reduction in cylinder volume induced during the compression stroke of the engine.
  • the secondary fuel is introduced into the cylinder prior to the end of the compression stroke of the piston, and, in particular, substantially at the start of the compression stroke.
  • the secondary fuel is fed into an air intake of the engine at a concentration which is less than its LFL.
  • Increased pressure is known to reduce the auto ignition temperature of a combustant. Furthermore, it is also known that increased pressure can change the flammability limit of a combustant. It is therefore likely that some of the products of decomposition of the secondary fuel could be experiencing traditional combustion under the increased pressure and temperature conditions in the engine cylinder and thus generating radicals, during the period between the pilot and main injections of the primary fuel.
  • H2 Hydrogen
  • C2H2 Acetylene
  • the primary fuel combusts following the pilot injection pulse and radicals are generated as part of the normal combustion process.
  • the secondary fuel may not start combustion at all, or alternatively stops traditional combustion before the primary fuel, as the secondary fuel has exceeded its LFL.
  • the remaining secondary fuel is still experiencing the standard combustion of the primary fuel, because the primary fuel has a lower LFL, which raises the temperature and / or pressure in the engine cylinder.
  • This method sustains the combustion and chemical decomposition cycles and therefore the availability of free radicals following the pilot injection of the primary fuel until the main injection of the primary fuel.
  • the availability and distribution of free radicals prior to the main injection of primary fuel ensures optimal combustion results.
  • Hydrogen itself would also serve as a secondary fuel but does not require the pyrolysis stage to be effective.
  • the secondary fuel is injected into the engine cylinder throughout the compression stroke to ensure that the secondary fuel is not consumed prior to the main injection of primary fuel.
  • a secondary fuel is injected into the engine cylinder between the pilot and main combustion events, the concentration of the co- combustant being above its LFL, as modified by the engine cylinder conditions. This has the advantage that it sustains the generation of radicals via traditional combustion.
  • Figure 1 is a schematic view of an engine utilising a combustion enhancement system.
  • Figures 2A and 2B are schematic side views of a cylinder of an engine to which the present invention may be applied with the piston shown in two different positions;
  • Figures 3A and 3B are schematic side views of the cylinders of Figures 2A and 2B with rotation applied thereto in order to produce a period of constant volume of the combustion chamber in accordance with an aspect of the invention
  • Figure 4 is a schematic view of a first embodiment of an electrical energy storage system for use in conjunction with the present invention.
  • Figure 5 is a schematic view of a second embodiment of a mechanical energy storage system for use in conjunction with the present invention.
  • FIG. 1 there is shown a schematic view of a combustion enhancement system for a combustion ignition diesel engine according to the invention.
  • An engine 1 has an electronic control unit (ECU) 2 connected to it by means of which operation of the engine 1 , such as fuel delivery to the engine 1 , may be controlled.
  • the system includes a turbo 3 by means of which the pressure of the air which is mixed with the fuel may be increased.
  • a motor 4 which is controlled by the ECU 2, is provided to control the delivery of a secondary fuel to the cylinders of the engine 1 for combustion.
  • the secondary fuel is Liquefied Petroleum Gas (LPG) which is stored under pressure in a canister 5 that is preferably replaceable or refillable.
  • LPG Liquefied Petroleum Gas
  • Other secondary fuels may also be used within the scope of the invention, the important thing being that it is hydrocarbon based and has a higher LFL (Lower Flammability Limit) than the primary fuel, which in the case of the illustrated example is diesel fuel.
  • LFL Lower Flammability Limit
  • the secondary fuel is used as an additive to generate a co-combustant as explained in more detail below.
  • the outlet of the canister 5 is connected to the engine air inlet 6 at a point 7 upstream of the turbocharger 3 so that the injection of the secondary fuel into the engine air inlet 6 prior to the turbocharger 3 occurs nominally at atmospheric pressure.
  • the flow rate of the secondary fuel into the air inlet 6 is controlled so that the concentration of the secondary fuel in the air inlet 6 is below the LFL of the secondary fuel and hence the mixture of air and secondary fuel in the air inlet is inflammable.
  • the pump 8 is preferably a peristaltic pump.
  • the pump 8 is controlled by the motor 4 which receives commands from the ECU 2. This controls the pump speed to ensure that the secondary fuel concentration is maintained within acceptable parameters.
  • This control loop nominally updates at least once per engine cycle.
  • a single ECU 2 controls the whole engine system and the communication between the ECU 2 and the pump motor 4 is via a CANbus 9.
  • the motor 4 driving the peristaltic pump 8 is preferably a stepper motor.
  • the ECU 2 also monitors the gas pressure on the input to the pump using pressure sensors 10 to check for leaks and also to alert the system when the secondary fuel supply is getting low.
  • a gas valve 11 such as an electric gas valve, is also provided in the outlet feed from the canister 5 which is operable to isolate the secondary fuel canister 5 is also controlled in a similar fashion.
  • a pressure regulator 12 for the gas is used to ensure that an accurately metered amount can be delivered to the injector 7, via the pump 8.
  • FIG. 2A and 2B there is shown a single cylinder 15 which houses a reciprocating piston 16 therein connected to a crankshaft 17 by a connecting rod 18 as a basic example of a reciprocating engine.
  • the piston 16 moves within the engine cylinder 15 due to the connection via the connecting rod 18.
  • the piston 16 describes both an up and a down stroke.
  • the piston speed is at a minimum at the end of the stroke when it changes direction. These points are defined as TDC (when the piston is at the top of its stroke) and BDC (when the piston is at the bottom of its stroke).
  • the engine cylinder 15 may be rotated in the same direction as the crankshaft 17 about a common axis as shown in Figures 3A and 3B.
  • the engine could instead be loaded during the power stroke in order to apply some resistance to the rotation of the crankshaft 17 during the power stroke in order to reduce the acceleration of the piston during the combustion event and thus produce a period of pseudo constant volume combustion sufficient to change the combustion environment and hence combustion characteristics.
  • pseudo constant volume it is meant that the acceleration of the piston downwards in the cylinder is reduced so that the rate of increase of the volume of the combustion chamber above the piston is correspondingly reduced.
  • this is akin to applying a brake to the crankshaft and thus retarding the normal rotation of the crankshaft relative to the engine cylinder.
  • This loading to force the engine to do additional work could be achieved in a number of different ways which are within the knowledge of the skilled. This can be achieved with selective mechanical, fluid, magnetic or electrical coupling.
  • this energy is instead stored, either in mechanical form or electrical form. This stored energy is then available to be used when required so as to deliver increased system efficiency in addition to combustion efficiency of the engine.
  • the loading could be applied for a continuous period during the first 90 degrees after TDC, and could be applied as a constant load or a load which varies during the period for which it is applied to match changing engine conditions.
  • the load could be applied during part of or the whole 90 degrees as indicated above.
  • the load could be applied in a pulsed manner during the period of application rather than in a single burst, which could make it more suitable for electric power generation or power supply to an electric drive system.
  • an electronic controller is provided, which may be separate to or integrated into the standard engine ECU.
  • FIG. 4 illustrates an electrical based system for loading the engine according to one embodiment of the invention.
  • An electrical generator 20 which could take the form of the existing alternator or an additional generator that could be used in electric propulsion, has its field windings 21 connected by a switching controller 22 (using components such as via FET switches or thyristors) when the additional engine load is required and the field winding 21 open circuited at other times.
  • the synchronisation of the switching controller is achieved using sensors 23 which monitor the rotational position of the engine and the engine cycle.
  • the generator provides pulses of electrical power. These are converted using an electronic power supply 24 to generate DC power, which can be used for electrical power 25, for battery charging 26 as in a standard or hybrid automobile, or the like.
  • the pulses of power especially if at a high voltage, could be used for direct drive of electric actuators or motors 27, or be used to energise an electrical accumulator 28.
  • FIG. 5 illustrates an alternative embodiment in which an electrical winding 30 is used with the same electronic switching arrangement.
  • the electrical winding 30 acts on a mass 31 that rotates.
  • the mass is connected to the crankshaft using a flexible coupling 32 (e.g. spring or torsion bar) that is designed to store energy when the mass is retarded.
  • a flexible coupling 32 e.g. spring or torsion bar
  • the retardation of the mass is released (by electronic switching of the winding) the stored energy is released to generate an acceleration of the crankshaft directly.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Output Control And Ontrol Of Special Type Engine (AREA)

Abstract

L'invention concerne un procédé destiné à améliorer l'efficacité d'un moteur à combustion interne (1) ayant un piston (15) conçu pour un mouvement de va-et-vient à l'intérieur d'un cylindre (16). La vitesse de déplacement du piston (15) le long du cylindre (16) par rapport à une chambre de combustion est au moins réduite pendant au moins une partie des premiers 90 degrés de chaque course de combustion. Le mouvement du piston (15) est réduit pendant une période continue commençant après le point mort haut du piston (15) à l'intérieur du cylindre (16) et ne se terminant pas au-delà de 90 degrés après le point mort haut. La réduction est appliquée à chaque cycle du moteur de telle sorte que le trajet du piston (15) pendant chaque cycle du moteur est cyclique mais pas complètement sinusoïdal pour au moins une partie des premiers 90 degrés de la course de combustion.
PCT/GB2018/000016 2017-02-02 2018-01-30 Perfectionnements apportés au fonctionnement de moteurs WO2018142097A1 (fr)

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GB1701707.0 2017-02-02
GB1701707.0A GB2559361A (en) 2017-02-02 2017-02-02 Improvements to operations of engines

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2020025915A1 (fr) 2018-08-01 2020-02-06 Combustion Order Ltd Dynamomètre synchrone en temps réel et système de commande

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EP2677144A1 (fr) * 2011-02-16 2013-12-25 Toyota Jidosha Kabushiki Kaisha Moteur a combustion interne a carburants multiples, et son procede de commande
EP2682588A1 (fr) * 2011-03-04 2014-01-08 Toyota Jidosha Kabushiki Kaisha Système de commande d'alimentation en carburant destiné à un moteur à combustion interne polycarburant
US8770158B1 (en) * 2013-06-05 2014-07-08 Thien Ton Consulting Services Co., Ltd. Hybrid vehicles with radial engines
US9194287B1 (en) * 2014-11-26 2015-11-24 Bernard Bon Double cam axial engine with over-expansion, variable compression, constant volume combustion, rotary valves and water injection for regenerative cooling

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Publication number Priority date Publication date Assignee Title
US3769788A (en) * 1972-03-09 1973-11-06 Conservor Inc Low pollution, high efficiency prime mover system and process
EP0137621A1 (fr) * 1983-08-15 1985-04-17 Andreas Demopoulos Moteurs à combustion interne
WO2004053345A1 (fr) * 2002-12-11 2004-06-24 Dapomot Oy Mecanisme a manivelle de moteur a combustion
US7007669B1 (en) * 2004-12-03 2006-03-07 Caterpillar Inc. Distributed ignition method and apparatus for a combustion engine
CN2883694Y (zh) * 2005-06-01 2007-03-28 庞乐钧 定容燃烧内燃机
DE102011084891A1 (de) * 2010-10-20 2012-04-26 Albert Magnus Thiel Gleichraumverbrennungsmotor
EP2677144A1 (fr) * 2011-02-16 2013-12-25 Toyota Jidosha Kabushiki Kaisha Moteur a combustion interne a carburants multiples, et son procede de commande
EP2682588A1 (fr) * 2011-03-04 2014-01-08 Toyota Jidosha Kabushiki Kaisha Système de commande d'alimentation en carburant destiné à un moteur à combustion interne polycarburant
US20130055984A1 (en) * 2011-09-07 2013-03-07 William Snell High efficiency engine for ultra-high altitude flight
US8770158B1 (en) * 2013-06-05 2014-07-08 Thien Ton Consulting Services Co., Ltd. Hybrid vehicles with radial engines
US9194287B1 (en) * 2014-11-26 2015-11-24 Bernard Bon Double cam axial engine with over-expansion, variable compression, constant volume combustion, rotary valves and water injection for regenerative cooling

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2020025915A1 (fr) 2018-08-01 2020-02-06 Combustion Order Ltd Dynamomètre synchrone en temps réel et système de commande

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GB2559361A (en) 2018-08-08
GB201701707D0 (en) 2017-03-22

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