WO2010043915A2

WO2010043915A2 - Throttle assembly and method

Info

Publication number: WO2010043915A2
Application number: PCT/GB2009/051402
Authority: WO
Inventors: Shaun Addy
Original assignee: Ip Consortium Limited
Priority date: 2008-10-17
Filing date: 2009-10-19
Publication date: 2010-04-22
Also published as: GB201108059D0; GB2476919A; WO2010043915A3

Abstract

A throttle assembly comprising first (181) and second (186) conduits through each of which a mixture of a fuel and an oxygen bearing gas may be passed, the first conduit (181) having means (170) for heating the mixture passed therethrough, the assembly being operable to supply the mixture from a selected one of the first (181) and second (186) conduits through an outlet (141) of the assembly.

Description

THROTTLE ASSEMBLY AND METHOD

FIELD OF THE INVENTION

The present invention relates to internal combustion engines. In particular but not exclusively the invention relates to cold start devices for internal combustion engines.

BACKGROUND

The starting of internal combustion engines from a cold condition (i.e. a condition in which the engine is substantially at ambient temperature and not at operational temperature) is known to be a problem under certain conditions. This is because in some cases difficulty is encountered causing a fuel/air mixture injected into the engine to ignite and generate sufficient power to cause sustained running of the engine. This problem is known to be particularly acute in engines running on heavy fuel such as diesel oil and kerosene.

FIG. 1 shows an induction system of a Wankel rotary engine 10 having a housing 40 in which a rotor 45 rotates. A throttle body 15 is connected to the housing. The throttle body supports a fuel injector 20 and has an air intake 30. The throttle body 15 is arranged to direct a mixture of fuel and air through an aperture 41 into a chamber 42 of the engine 100. A butterfly valve 32 is arranged to control an amount of air that can flow through the air intake 30 and into the throttle body 15.

It is known to provide a cold start device in the form of a hot air blower arranged to blow hot air into an air intake of an engine. It is also known to supply more volatile fluids or gases to a fuel/air mixture passing into the chamber 42 to encourage starting of the engine.

A disadvantage of these known methods is that an external power source and/or starting rig is required.

STATEMENT OF THE INVENTION

In a first aspect of the invention there is provided a throttle assembly comprising first and second conduits through each of which a mixture of a fuel and an oxygen bearing gas may be passed, the first conduit having means for heating the mixture passed therethrough, the assembly being operable to supply the mixture from a selected one of the first and second conduits through an outlet of the assembly.

The assembly may comprise director means for directing a supply of the gas through the selected one of the first and second conduits.

Preferably the assembly comprises a restrictor member arranged to control the rate of flow of gas through the second conduit.

The restrictor member may also be referred to as a throttle member in some embodiments.

Preferably the restrictor member comprises the director means.

The restrictor member may be arranged to control the rate of flow of gas through the selected one of the first and second conduits.

Preferably in a first condition the restrictor member is arranged to supply the flow of gas through the first conduit and in a second condition the restrictor member is arranged to supply the flow of gas through the second conduit.

Preferably in a third condition the restrictor member is arranged to supply the flow of gas through the first and second conduits substantially simultaneously.

The first, second and third conditions may be arranged whereby a flow of the mixture may be established from the outlet via the first conduit and subsequently via the second conduit without substantially interrupting the flow of mixture from the outlet.

Preferably in the first condition the restrictor member is arranged to provide a flowpath for the gas from a gas inlet of the assembly through the first conduit, the restrictor member being arranged to provide a channel arranged to deflect the gas into the first conduit.

In the second condition the restrictor member may be arranged to allow the gas to flow substantially directly into the second conduit from the gas inlet of the assembly. The restrictor member may be provided with an aperture therethrough by means of which a flowpath may be provided directly into the second conduit.

Preferably the assembly comprises a fuel injector arranged to inject fuel into a flow of gas whereby the restrictor member is arranged to direct a mixture of the fuel and gas to the selected one of the first and second conduits.

Alternatively the assembly may comprise a first fuel injector arranged to inject fuel into the first conduit and a second fuel injector arranged to inject fuel into the second conduit.

The second fuel injector may be arranged to inject fuel into the second conduit along a direction substantially parallel to a direction of flow of gas through the second conduit.

Preferably the second fuel injector is arranged to inject fuel into the second conduit along a direction substantially coaxial with the second conduit.

The restrictor means may comprise a rotator member rotatable between the first, second and third conditions.

The means for heating the mixture may comprise means for heating the mixture to a temperature not exceeding a temperature at which combustion of the fuel/air mixture occurs.

The means for heating the mixture may comprise at least one heat exchange element. The element may be provided away from an outer boundary of flow of the mixture through the assembly.

Preferably the means for heating the mixture comprises a heat source.

Preferably the heat source comprises an electric heating element, optionally a glow plug.

Preferably the at least one heat exchange element comprises at least one fin element.

The assembly preferably comprises a plurality of fin elements. Preferably the at least one fin element is provided in thermal communication with a stem, the heat source being arranged to heat the stem.

Preferably the at least one element is arranged to heat the at least one fin to a temperature below that at which combustion of the mixture occurs.

Preferably the heat source is arranged to heat the at least one fin to a temperature of at least 300⁰C, optionally a temperature of at least 400⁰C.

The heat source may be arranged to heat the at least one fin to a temperature not exceeding 300⁰C, optionally a temperature not exceeding 400⁰C. The heat source may be arranged to heat the at least one fin to a temperature in the range 300-400⁰C, optionally a temperature in the range 400-500⁰C.

The assembly may be coupled to an inlet of a combustion chamber.

The director means may be configured to provide means for switching on and off the means for heating the mixture.

Preferably the director means is provided with at least one electrical contact arranged to complete a circuit thereby to switch on the means for heating the mixture.

By completion of a circuit is included completion of a circuit to directly pass current to the means for heating the mixture or to trigger supply of current to the means for heating the mixture, such as relay, or a control signal to a microcontroller.

In a second aspect of the invention there is provided an engine having a throttle assembly according to the first aspect of the invention.

In a third aspect of the invention there is provided one selected from amongst a vehicle, an aircraft and a vessel having an engine having a throttle assembly according to the first aspect of the invention.

In a fourth aspect of the invention there is provided a method comprising: providing a throttle assembly comprising first and second conduits through each of which a mixture of a fuel and an oxygen bearing gas may be passed, the first conduit having means for heating the mixture passed therethrough, the assembly being operable to supply the mixture from a selected one of the first and second conduits through an outlet of the assembly; passing a mixture of fuel and oxygen bearing gas through the first conduit; and heating the mixture by means of the means for heating.

Preferably the method further comprises passing the mixture through the second conduit.

The throttle assembly may be coupled to an engine and arranged to supply the mixture to the engine.

Preferably the step of passing the mixture through the first conduit is performed during a process of starting the engine, the step of passing the mixture through the second conduit being performed after the engine has started.

In a fifth aspect of the invention there is provided a heat exchange assembly for an internal combustion engine, the assembly being arranged to heat a mixture of a fuel and an oxygen bearing gas before the mixture passes into a combustion chamber of the engine, the assembly comprising at least one heat exchange element provided in a path of travel of the mixture through the assembly, the at least one element being provided away from an outer boundary of flow of the mixture through the assembly, wherein the at least one heat exchange element comprises a fin element.

In a further aspect of the invention there is provided a heat exchanger assembly for an internal combustion engine, the assembly being arranged to provide substantially uniform heating of a mixture of a fuel and an oxygen bearing gas before the mixture passes into a combustion chamber of the engine, the assembly comprising at least one heat exchange element arranged to heat the mixture to a temperature not exceeding a temperature at which combustion of the mixture occurs.

Preferably the at least one element is provided away from an outer boundary of flow of the mixture through the assembly.

In a still further aspect of the invention there is provided a heat exchanger assembly for an internal combustion engine, the assembly being arranged to heat a mixture of a fuel and an oxygen bearing gas before the mixture passes into a combustion chamber of the engine, the assembly comprising at least one heat exchange element provided in a path of travel of the mixture through the assembly, the at least one element being provided away from an outer boundary of flow of the mixture through the assembly.

In other words, the heat exchanger is provided in the path of travel of the mixture of fuel and oxygen bearing gas and is not merely provided by a wall of a conduit through which the fuel and oxygen bearing gas pass. It is to be understood that the heat exchanger is provided in an induction portion of the engine.

Preferably the heat exchanger according to any earlier aspect of the invention is arranged to heat the mixture to a temperature not exceeding a temperature at which combustion of the mixture occurs.

The fuel may be a hydrocarbon-bearing liquid fuel in the form of one selected from amongst a vapour, atomised particles and droplets. Particles of the fuel may be entrained in the flow of oxygen bearing gas. The oxygen bearing gas is preferably air. Other gases are also useful.

Embodiments of the invention have been found to dramatically improve an ease with which an engine may be started in all conditions (whether hot or cold) using kerosene based aviation fuels (JP-8 and Jet-A1 ). A particularly significant improvement is seen when starting engines running on gasoline.

By heating the fuel as well as the oxygen bearing gas in which the fuel has become entrained or vaporised (e.g. in the form of a mist and/or a vapour) a dramatic improvement in an ease with which an engine may be started may be observed. This is in contrast to known techniques in which only the oxygen bearing gas is heated, before it enters the throttle body of an engine.

In some embodiments of the invention rotary engines were observed to start the first time a rotor of each engine was turned when a heat exchange assembly according to an embodiment of the invention was employed.

Preferably the assembly comprises a heat source.

The heat source may comprise an electric heating element, optionally a glow plug. The at least one heat exchange element may comprise a fin element.

The assembly may comprise a plurality of fin elements.

The at least one fin element may be arranged to project from a stem.

The heat source may be arranged to heat the stem.

The heat source may be arranged to heat the stem and the fins to a temperature below that at which combustion of the fuel/oxygen bearing gas mixture occurs.

This has the advantage that substantially none of the fuel/oxygen bearing gas mixture is burned before the mixture enters the chamber of the engine, enabling more power to be developed by the engine.

The heat source may be arranged to heat the stem and fins to a temperature of at least 300⁰C, optionally a temperature of at least 400⁰C.

Other temperatures are also useful.

The assembly may be arranged to be coupled to an outlet of a throttle body and to an inlet of a combustion chamber thereby facilitating insertion of the assembly in a flowpath of the fuel/oxygen bearing gas mixture.

The assembly may be provided in an adaptor housing, the adaptor housing having an inlet arranged to be coupled to the outlet of the throttle body and an outlet arranged to be coupled to an inlet of a combustion chamber.

The assembly may be arranged to be inserted within a fluid conduit downstream from a source of the fuel/oxygen bearing gas mixture.

The assembly may be formed from a metallic material.

The assembly may comprise a portion formed from at least one selected from amongst copper and brass. In a further aspect of the invention there is provided an engine comprising an assembly according to an aspect of the invention inserted within a fluid conduit of the engine downstream from a source of a fuel/oxygen bearing gas mixture.

The source of the fuel may be a fuel injector of the engine.

The assembly may be provided substantially coaxial of a flow of fuel injected by the fuel injector.

Alternatively the assembly may be provided downstream from a carburettor arranged to generate a fuel/oxygen bearing gas mixture.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described with reference to the accompanying figures in which:

FIGURE 1 shows a known arrangement for injecting a fuel/air mixture into a combustion chamber of a rotary engine;

FIGURE 2 is a schematic illustration of a throttle assembly according to an embodiment of the present invention in a bypass or mixture heating mode of operation in (a) rear elevation showing a mixture outlet, (b) cross-section along line A-A of (a), (c) front elevation showing a fuel and gas inlet and (d) 3D cross-section;

FIGURE 3 is a schematic illustration of a throttle assembly according to the embodiment of FIG. 2 in a normal mode of operation in (a) rear elevation showing a mixture outlet, (b) cross-section along A-A of (a), (c) front elevation showing a fuel and gas inlet and (d) 3D cross-section along A-A;

FIGURE 4 is a schematic illustration of a throttle assembly according to an embodiment of the present invention having a twin injector arrangement in a bypass or mixture heating mode of operation in (a) rear elevation showing a mixture outlet, (b) cross- section along A-A of (a), (c) front elevation showing a fuel and gas inlet and (d) 3D cross-section along A-A; and FIGURE 5 is a schematic illustration of a throttle assembly according to the embodiment of FIG. 4 in a normal mode of operation in (a) rear elevation showing a mixture outlet, (b) cross-section along A-A of (a), (c) front elevation showing a fuel and gas inlet and (d) 3D cross-section along A-A;

FIGURE 6 shows an engine according to an embodiment of the invention having a heat exchanger provided downstream from a throttle body of the engine;

FIGURE 7 shows a heat exchanger module according to an embodiment of the invention; and

FIGURE 8 shows the heat exchanger module of FIG. 7 provided in an adaptor.

DETAILED DESCRIPTION

FIG. 2 shows a throttle assembly 101 according to an embodiment of the invention. The assembly 101 has a throttle body 1 15 having a gas inlet 130 having first and second inlet apertures 130.1 , 130.2. The first inlet aperture 130.1 is arranged to allow fuel and an oxygen-bearing gas such as air to pass into the assembly 101 . The second inlet aperture 130.2 is arranged to allow an oxygen bearing gas to pass into the assembly 101 when required.

The assembly 101 has a corresponding outlet 141 in the form of an aperture through which a mixture of the fuel and the oxygen bearing gas may pass out from the assembly 101.

A fuel injector 120 is shown, the injector 120 being arranged to inject a flow of fuel into the first inlet aperture 130.1. A flow of air F into inlet aperture 130.1 is also shown in FIG. 2(a). It is to be understood that the assembly is arranged to allow the air to mix with the flow of fuel to form a fuel/air mixture.

The assembly 101 is provided with two separate conduits through which the mixture may flow through the assembly 101 . The first conduit 181 is provided with a heat exchange module 170 that is operable to heat mixture passing through the first conduit 181. The second conduit 186 is arranged to allow mixture to pass through the assembly in a substantially direct path from the inlet 130 to the outlet 141 . The inlet 130 and outlet 141 are therefore substantially 'inline' with a substantially unrestricted flow path therebetween. The inlet to the second conduit 186 may therefore also be referred to as an unrestricted port. Mixture flowing through the second conduit 186 experiences substantially no bends thereby reducing a resistance to flow of mixture through the conduit 186 relative to a conduit having one or more bends.

The throttle assembly 101 has a rotatable restrictor member 190 provided close to the inlet 130 and arranged to be rotatable about an axis A. The restrictor member is provided with a channel 191 in a face thereof arranged such that with the restrictor member 190 in a first rotational condition the channel 191 is presented to the first inlet aperture 130.1 . Mixture passing through the assembly 101 is thereby directed by the channel 191 through the first conduit 181 and not through the second conduit 186.

The restrictor member 190 also has first and second apertures 192.1 , 192.2 formed therethough and arranged such that in a second rotational condition of the restrictor member 190 the first and second apertures 192.1 , 192.2 align with the first and second inlet apertures 130.1 , 130.2 respectively of the throttle body 1 15.

In the second rotational condition a flow path is provided allowing mixture passing through the first inlet aperture 130.1 to pass through the first aperture 192.1 of the restrictor member 190. In this condition a flowpath is also provided for air to pass through the second inlet aperture 130.2 and through the second aperture 192.2 of the restrictor member 190. Thus, mixture passing through the first aperture 192.1 of the restrictor member and air passing through the second aperture 192.2 of the restrictor member 190 are both directed to pass through the second conduit 186 to the outlet 141 .

This feature allows a greater flow of air through the second conduit 186 compared with the first conduit 181 allowing the engine to develop larger amounts of power during normal operation (as opposed to a start-up or warm-up configuration).

It is to be understood that in the embodiments shown in FIG.'s 2 to 5, in the second rotational condition of the restrictor member 190 (FIG. 3 and FIG. 5) a flowpath does not exist for mixture to pass through the channel 191 and into the first conduit 181 . Other arrangements are also useful, however. In the embodiment of FIG. 2 and FIG. 3 the restrictor member 190 is arranged such that as the restrictor member 190 is rotated from the first rotational position to the second rotational position a flow of mixture through the first conduit 181 is decreased and a flow of mixture through the second conduit 186 is increased, thereby ensuring that a flow of mixture from the outlet 141 is not interrupted as the restrictor member 190 is rotated.

In the configuration shown in FIG. 2 the throttle assembly 101 is shown in a "bypass" mode of operation (also referred to as a 'start-up' or 'warm-up' configuration) in which the restrictor member 190 is in the first condition and mixture is directed through the first conduit 181.

In the configuration of FIG. 3 the throttle assembly 101 is shown in a "normal" mode of operation in which the restrictor member 190 is in the second condition and mixture is directed through the second conduit 186.

In the embodiment shown the relative positions of the channel 191 , apertures 192.1 , 192.2 and apertures 130.1 , 130.2 are such that the second rotational condition of the restrictor member 190 corresponds to a range of rotational positions. In other words, the restrictor member 190 may be rotated to one of a range of rotational positions at which mixture is directed only into the second conduit 186.

As the restrictor member 190 is rotated between these rotational positions a cross- sectional area of a flow path from the inlet apertures 130.1 , 130.2 to the restrictor member apertures 192.1 , 192.2 changes thereby to allow a rate of flow of mixture through the assembly to be controlled.

It is to be understood that the bypass mode of operation is useful when starting an engine from cold, where a high rate of flow of mixture through the assembly 101 is not required. The presence of the heat exchange assembly 170 increases a thermal energy of the mixture thereby enabling starting of an engine from cold.

Provision of first and second conduits 181 , 186 has the advantage that when a high throughput of mixture is required, for example during relatively high power operation of the engine, the heat exchange module 170 may be eliminated from the flowpath of the mixture thereby increasing a rate at which mixture may be passed through the assembly 101.

FIG.'s 4 and 5 show a throttle assembly 201 according to an embodiment of the invention similar to that of FIG.'s 2 and 3 but having first and second fuel injectors 220.1 , 220.2. In the embodiment of FIG. 4 and FIG. 5 each fuel injector 220.1 , 220.2 is arranged directly to inject fuel into a respective one of the first and second conduits 281 , 286.

The first fuel injector 220.1 is arranged to inject a flow of fuel into the first conduit 281 through a first injector aperture 221 in a direction towards a heat exchange assembly 270 provided in the first conduit 281 .

The second fuel injector 220.2 is arranged to inject a flow of fuel into the second conduit 286 through a second injector aperture 222. This differs from the arrangement of the embodiment of FIG.'s 2 and 3 in that fuel is not injected into the second conduit 286 via the inlet aperture 230.1 as in the case of the embodiment of FIG.'s 2 and 3. Rather, air is arranged to pass into the second conduit 286 through the first and second inlet apertures 230.1 , 230.2 and fuel is arranged to pass into the second conduit 286 through the second injector aperture 222. The second injector aperture 222 is located between the first and second inlet apertures 230.1 , 230.2 in the embodiment shown.

In FIG.4 the assembly 201 is shown in a bypass mode in which a channel 291 of the restrictor member 290 is arranged to direct a flow of air from the first inlet 230.1 into the first conduit 281. In this mode the first fuel injector 220.1 is arranged to inject a corresponding flow of fuel into the first conduit 281 . The restrictor member 290 is arranged to block the second air inlet 230.2 so that substantially no air flows into the second conduit 286.

In FIG. 5 the assembly is shown in a normal mode of operation in which the restrictor member 290 blocks a flowpath of air from the inlet 230.1 through the first conduit 281 and the first fuel injector 220.1 no longer injects fuel into the first conduit 281. In the normal mode, air passes through the inlets 230.1 , 230.2 and through first and second apertures 292.1 , 292.2 in the restrictor member 290. As the air passes through the restrictor member 290 and into the second conduit 286 it mixes with fuel injected by the second fuel injector 220.2. The presence of two fuel injectors 220.1 , 220.2 has the advantage that one or both of the injectors 220.1 , 220.2 can be positioned such that a centreline of a flow of fuel from the injector 220.1 , 220.2 is substantially parallel to a centreline of a portion of the respective conduit into which fuel is injected, thereby to reduce an amount of fuel impinging on a wall of the conduit. A risk that fuel will condense or otherwise deposit on the wall of the conduit is also reduced. This feature is particularly useful at high rates of flow of mixture through a conduit, for example through the second conduit 286 during high power engine operations.

In the embodiment of FIG.'s 4 and 5 the injector is arranged such that the centreline of the flow of fuel from the injector 220.2 is substantially coincident with a centreline of the portion of the second conduit 286 into which fuel is injected. In other words, the flow of fuel from the injector 220.2 is arranged to be substantially coaxial with the second conduit 286.

The arrangement of FIG.'s 4 and 5 has the further advantage that a greater flow of fuel and air through the second conduit 286 may be established since the presence of the fuel injector 220.2 does not reduce a cross-sectional area of the first air inlet 230.1 .

As described above, eliminating the heat exchanger from a flowpath of mixture when the engine is developing relatively large power enhances an efficiency of operation and a maximum power the engine can develop. This is in part due to reduced disruption of airflow in the absence of a heat exchanger in the flowpath.

It is to be understood that at relatively low throttle openings (i.e. relative low rates of airflow through the throttle assembly) the presence of an airflow disrupter such as a heat exchanger does not result in a significant amount of fuel loss from a fuel-bearing airflow. However, at relatively high flow rates a size of fuel droplets in the airflow can increase, increasing a likelihood of fuel deposition on objects in the flowpath and thereby fuel loss from the airflow.

Other arrangements are also useful.

In some embodiments the assembly is arranged to energise the heat exchange assembly 170, 270 when the restrictor member 190, 290 is in a prescribed condition. In some embodiments the prescribed condition corresponds to a condition in which the restrictor member is arranged to direct air through the first conduit only. In some embodiments a further position of the restrictor member 190, 290 is provided at which the heat exchange assembly is not energised but air is also directed to flow through the first conduit only.

Thus, in some embodiments the restrictor member is provided with means for energising the heat exchange assembly. For example, the restrictor member may be provided with electrical contacts or actuating means arranged to close an electrical circuit thereby to directly or indirectly (e.g. by means of a relay or microcontroller) energise the heat exchange assembly 170, 270.

The assembly may be further arranged to preheat fuel injected by one or more injectors of the assembly.

In use with an engine in an off condition the assembly may be placed in a start condition in which the heat exchange assembly 170, 270 is energised and air is directed by the restrictor member 190, 290 to flow through the first conduit only.

Once the engine has been started the restrictor member 190, 290 may be moved to an idle condition in which air is still directed to flow through the first conduit only. In some alternative embodiments, in the idle condition air may be directed to flow through the first and second conduits simultaneously. In some embodiments, in the idle condition air may be directed to flow through the second conduit only.

In some embodiments the assembly may be arranged to pass mixture through the first conduit to heat the mixture when required during operation of the engine after starting. For example if an inlet air temperature falls below a prescribed temperature (e.g. during cold weather and/or at altitude), when a risk of icing exists or any other suitable conditions.

It is to be understood that other arrangements are also useful. In some embodiments the first conduit is only used for starting the engine. Once the engine has started the restrictor member is moved to a condition in which air is directed through the second conduit only. FIG. 6 shows an engine 300 according to an embodiment of the invention in which a heat exchange assembly 350 has been installed downstream from a throttle body 315 of the engine 300. It is to be understood that the heat exchange assembly 350 is suitable for use with a throttle assembly according to either of the embodiments of FIG.'s 2 and 3 or 4 and 5.

The heat exchange assembly 350 has a heat exchange module 370 which is shown separately in FIG. 7. In FIG. 8 the module 370 is shown installed in an adaptor frame 360 thereby to provide the heat exchange assembly 350.

The heat exchange module 370 has a plurality of fins or vanes 372 in the form of substantially flat sheets of a material of relatively high thermal conductivity. The sheets are arranged such that a plane of each sheet lies in a plane substantially parallel to a direction of flow of fluid through the heat exchange assembly 350. Other arrangements are also useful. Other shapes of fins or vanes are also useful.

A stem member 374 in the form of a hollow cylindrical member is arranged to pass through and in contact with each of the fins 372. The stem member 374 is sized to receive an electrical heating element (not shown) through an aperture 375 formed in a housing portion 376 of the heat exchange module 370. The housing portion 376 is arranged to support the stem member 374.

The heating element is in the form of an elongate rod arranged to heat the stem member 374 and thereby the fins 372 of the heat exchange module 370.

The adaptor frame 360 is arranged to allow the assembly 350 to be mounted in a throttle body 315 (FIG. 6) or other suitable component. An aperture 365 is formed in the adaptor frame 360 at a location corresponding to that of the aperture 375 formed in the housing portion 376 of the heat exchanger module 370. In some embodiments this aperture is provided to allow the heating element to be inserted into the stem member 374 through the adaptor frame 360. In some embodiments the aperture also facilitates management of electrical cabling supplying power to the heating element.

In use, the heating element of the heat exchanger assembly 350 is energised to heat the heat exchange module 370 as a fuel/air mixture is passed through the heat exchanger assembly 350. The electrical element is energised so as to heat the heat exchange module 370 to a temperature below that at which combustion of the fuel/air mixture would occur, but a temperature that is sufficiently high to facilitate starting of an engine from cold if a sufficient volume of mixture is passed therethrough. The electrical heating element is arranged to be energised for a period of time long enough to heat a sufficient quantity of fuel/air mixture passing therethrough to allow starting of the engine.

The heat exchanger assembly 350 is shaped and configured to allow heating of the module 370 in a relatively uniform manner. Thus the formation of 'hot spots' being regions of the module 370 that reach a temperature sufficient to cause combustion of the fuel/air mixture may be avoided.

In some embodiments the assembly 350 is arranged such that the heat exchange module 370 has sufficient thermal mass to enable the fins 372 of the module 370 to remain at a temperature sufficient to heat a fuel/air mixture flowing therethrough for a period of time following termination of the supply of power to the heating element. The engine 300 may be arranged whereby this period of time is sufficiently long to ensure reliable starting of an engine from cold.

In some embodiments of the invention heating of the fins 372 of the module 370 is performed by heating the housing portion 376 of the heat exchange assembly 350 in addition to or instead of heating a stem 374 of the module 370. Thus, in some embodiments the module 370 is not provided with a stem 374.

In some embodiments the housing portion 376 is provided with a heating element therein and/or therearound. In some embodiments at least a portion of the adaptor frame 360 is heated thereby to heat fins 372. It is to be understood that in some embodiments the fins 372 are in direct thermal contact with the housing portion 376.

It is to be understood that a thermal capacitance of the heat exchange module 370 may be increased by increasing a thickness of a wall of the housing portion 376 of the module. The thicker the wall of the housing portion 376 the higher the thermal capacitance and therefore the longer the 'cranking period' of the engine. The cranking period is the period of time for which heated mixture may be supplied to the combustion chamber of the engine. However, it follows that a larger amount of energy is typically required in order to heat the frame in this case. Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example "comprising" and "comprises", means "including but not limited to", and is not intended to (and does not) exclude other moieties, additives, components, integers or steps.

Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith.

Claims

CLAIMS:

1. A throttle assembly comprising first and second conduits through each of which a mixture of a fuel and an oxygen bearing gas may be passed, the first conduit having means for heating the mixture passed therethrough, the assembly being operable to supply the mixture from a selected one of the first and second conduits through an outlet of the assembly.

2. An assembly as claimed in claim 1 comprising director means for directing a supply of the gas through the selected one of the first and second conduits.

3. An assembly as claimed in claim 1 or claim 2 comprising a restrictor member arranged to control the rate of flow of gas through the second conduit.

4. An assembly as claimed in claim 3 as dependent on claim 2 wherein the restrictor member comprises the director means.

5. An assembly as claimed in claim 4 wherein the restrictor member is arranged to control the rate of flow of gas through the selected one of the first and second conduits.

6. An assembly as claimed in claim 5 wherein in a first condition the restrictor member is arranged to supply the flow of gas through the first conduit and in a second condition the restrictor member is arranged to supply the flow of gas through the second conduit.

7. An assembly as claimed in claim 6 wherein in a third condition the restrictor member is arranged to supply the flow of gas through the first and second conduits substantially simultaneously.

8. An assembly as claimed in claim 7 wherein the first, second and third conditions are arranged whereby a flow of the mixture may be established from the outlet via the first conduit and subsequently via the second conduit without substantially interrupting the flow of mixture from the outlet.

9. An assembly as claimed in any one of claims 6 to 8 wherein in the first condition the restrictor member is arranged to provide a flowpath for the gas from a gas inlet of the assembly through the first conduit, the restrictor member being arranged to provide a channel arranged to deflect the gas into the first conduit.

10. An assembly as claimed in claim 9 wherein in the second condition the restrictor member is arranged to allow the gas to flow substantially directly into the second conduit from the gas inlet of the assembly..

1 1. An assembly as claimed in claim 10 wherein the restrictor member is provided with an aperture therethrough by means of which a flowpath may be provided directly into the second conduit.

12. An assembly as claimed in claim 3 or any one of claims 4 to 1 1 depending through claim 3 comprising a fuel injector arranged to inject fuel into a flow of gas whereby the restrictor member is arranged to direct a mixture of the fuel and gas to the selected one of the first and second conduits.

13. An assembly as claimed in claim 3 or any one of claims 4 to 1 1 depending through claim 3 comprising a first fuel injector arranged to inject fuel into the first conduit and a second fuel injector arranged to inject fuel into the second conduit.

14. An assembly as claimed in claim 13 wherein the second fuel injector is arranged to inject fuel into the second conduit along a direction substantially parallel to a direction of flow of gas through the second conduit.

15. An assembly as claimed in claim 13 wherein the second fuel injector is arranged to inject fuel into the second conduit along a direction substantially coaxial with the second conduit.

16. An assembly as claimed in claim 7 or any one of claims 8 to 15 depending through claim 7 wherein the restrictor means comprises a rotator member rotatable between the first, second and third conditions.

17. An assembly as claimed in any preceding claim wherein the means for heating the mixture comprises means for heating the mixture to a temperature not exceeding a temperature at which combustion of the fuel/air mixture occurs.

18. An assembly as claimed in any preceding claim wherein the means for heating the mixture comprises at least one heat exchange element, the element being provided away from an outer boundary of flow of the mixture through the assembly.

19. An assembly as claimed in claim 18 wherein the means for heating the mixture further comprises a heat source.

20. An assembly as claimed in claim 19 wherein the heat source comprises an electric heating element, optionally a glow plug.

21 . An assembly as claimed in any one of claims 18 to 20 wherein the at least one heat exchange element comprises at least one fin element.

22. An assembly as claimed in claim 21 comprising a plurality of fin elements.

23. An assembly as claimed in claim 21 or claim 22 wherein the at least one fin element is provided in thermal communication with a stem, the heat source being arranged to heat the stem.

24. An assembly as claimed in any one of claims 21 to 23 wherein the at least one element is arranged to heat the at least one fin to a temperature below that at which combustion of the mixture occurs.

25. An assembly as claimed in claim 24 wherein the heat source is arranged to heat the at least one fin to a temperature of at least 300⁰C, optionally a temperature of at least 400⁰C.

26. An assembly as claimed in any preceding claim arranged to be coupled to an inlet of a combustion chamber.

27. An assembly as claimed in claim 2 or any one of claims 2 to 26 depending through claim 2 wherein the director means is configured to provide means for switching on and off the means for heating the mixture.

28. An assembly as claimed in claim 27 wherein the director means is provided with at least one electrical contact arrange to complete a circuit thereby to switch on the means for heating the mixture.

29. An engine having a throttle assembly as claimed in any preceding claim.

30. One selected from amongst a vehicle, an aircraft and a vessel having an engine having a throttle assembly as claimed in any one of claims 1 to 28.

31 . A method comprising: providing a throttle assembly comprising first and second conduits through each of which a mixture of a fuel and an oxygen bearing gas may be passed, the first conduit having means for heating the mixture passed therethrough, the assembly being operable to supply the mixture from a selected one of the first and second conduits through an outlet of the assembly; passing a mixture of fuel and oxygen bearing gas through the first conduit; and heating the mixture by means of the means for heating.

32. A method as claimed in claim 31 further comprising passing the mixture through the second conduit.

33. A method as claimed in claim 31 or 32 wherein the throttle assembly is coupled to an engine and arranged to supply the mixture to the engine.

34. A method as claimed in claim 33 as dependent on claim 32 wherein the step of passing the mixture through the first conduit is performed during a process of starting the engine, the step of passing the mixture through the second conduit being performed after the engine has started.

35. A heat exchange assembly for an internal combustion engine, the assembly being arranged to heat a mixture of a fuel and an oxygen bearing gas before the mixture passes into a combustion chamber of the engine, the assembly comprising at least one heat exchange element provided in a path of travel of the mixture through the assembly, the at least one element being provided away from an outer boundary of flow of the mixture through the assembly, wherein the at least one heat exchange element comprises a fin element.

36. An assembly as claimed in claim 35 comprising a plurality of fin elements.

37. An assembly as claimed in claim 35 or claim 36 wherein the at least one fin element is arranged to project from a stem.

38. An assembly as claimed in claim 37 further comprising a heat source, the heat source being arranged to heat the stem.

39. An assembly as claimed in claim 38 wherein the heat source is arranged to heat the stem and the at least one fin to a temperature below that at which combustion of the fuel/oxygen bearing gas mixture occurs.

40. An assembly as claimed in claim 39 wherein the heat source is arranged to heat the stem and at least one fin to a temperature of at least 300 ^<€, optionally a temperature of at least 400 ^<€.

41 . An assembly as claimed in any one of claims 35 to 40 arranged to be coupled to an outlet of a throttle body and to an inlet of a combustion chamber thereby facilitating insertion of the assembly in a flow-path of the mixture.

42. An assembly as claimed in claim 41 provided in an adaptor housing, the adaptor housing having an inlet arranged to be coupled to the outlet of the throttle body and an outlet arranged to be coupled to an inlet of a combustion chamber.

43. An assembly as claimed in any one of claims 35 to 42 arranged to be inserted within a fluid conduit downstream from a source of the mixture.

44. An assembly as claimed in any one of claims 35 to 43 formed from a metallic material.

45. An assembly as claimed in any one of claims 35 to 44 comprising a portion formed from at least one selected from amongst copper and brass.

46. An engine comprising an assembly as claimed in any one of claims 35 to 45 inserted within a fluid conduit of the engine downstream from a source of a mixture of a fuel and an oxygen bearing gas.

47. An engine as claimed in claim 46 wherein the source of the fuel is a fuel injector of the engine.

48. An engine as claimed in claim 47 wherein the assembly is provided substantially coaxial of a flow of fuel injected by the fuel injector.

49. An assembly substantially as hereinbefore described with reference to the accompanying drawings.

50. An engine substantially as hereinbefore described with reference to the accompanying drawings.

51 . One selected from amongst a vehicle, an aircraft and a vessel having an engine having a throttle assembly substantially as hereinbefore described with reference to the accompanying drawings.

52. A method substantially as hereinbefore described with reference to the accompanying drawings.