Field of the Invention

The invention relates to catalyst mounting in internal combustion engines and particularly, but not exclusively to internal combustions engines operating an engine cycle as disclosed in WO2015/040427 and WO2015/040428, the contents of which are incorporated herein by reference.

Background to the Invention

It is known to provide a catalyst in a combustion chamber of an internal combustion engine to facilitate reactions in fluids injected into in the combustion chamber. Oxidation of such catalysts is a problem as oxidation of a catalyst may have a detrimental effect on the catalytic reaction performance.

Summary of the Invention

The invention includes an internal combustion engine as specified in claim 1.

The invention provides an internal combustion engine injector mounting as specified in claim 10.

The invention also includes an internal combustion engine injector mounting as specified in claim 16.

Brief Description of the Drawings

In order that the invention may be well understood, some examples thereof, which are given by way of example only, will now be described with reference to the drawings in which:

Figure l is a schematic representation of an internal combustion engine;

Figure 2 is a schematic representation of an example of valving for the internal combustion engine of Figure 1; Figure 3 is a schematic representation of an example of a controller for the internal combustion engine of Figure 1;

Figure 4 is a schematic representation of an injector and an injector mounting of the internal combustion engine of the valving of Figure 2

Detailed Description

Referring to Figure 1, an internal combustion engine 10 comprises a variable volume combustion chamber 12 defined by a cylinder head 14, an engine block 16 and a body that is movable in a cylinder defined by the engine block. In the illustrated example, the body is a reciprocating piston 18 that is connected with a crankshaft 20 by a connecting rod 22. Although not essential, in the illustrated example, the combustion chamber is a single variable size volume bounded by the walls against which the piston seals, the piston head and the cylinder head 14.

The internal combustion engine 10 comprises first valving 24 operable to admit an intake gas comprising an aspirant into the combustion chamber 12. In the illustrated example, the intake gas is air received from an air supply system 26 connected with the first valving 24. The air supply system 26 may comprise a manifold configured to receive ambient air and conduct the air to the first valving 24. The first valving 24 may comprise one or a plurality of valves connected with the air supply system 26. The air supply system 26 may comprise suitable filters to clean the air. Although not essential, the intake air may be pressurised by turbo charging or supercharging, both of which are techniques that will be familiar to those in skilled in the art and so will not be described in detail herein.

The internal combustion engine 10 comprises second valving 30 that is connected with an aqueous fluid supply system 32 and a reservoir 34 containing a fuel for the internal combustion engine. The second valving 30 is operable to admit heated aqueous fluid from the aqueous fluid supply system 32 and fuel from the reservoir 34 into the combustion chamber 12 as a mixture or blend. The heated aqueous fluid received from the aqueous fluid supply system comprises droplets, vapour or a combination thereof. Preferably, the heated aqueous fluid, or at least the major proportion thereof, is steam. As shown in Figure 2, the second valving 30 may comprise one or a plurality of injectors 36 that are arranged to inject the aqueous fluid/fuel mixture into the combustion chamber 12 and one or more valves 38 disposed between the aqueous fluid supply system 32 and the injector or injectors 36 so as to isolate the injectors from the aqueous fluid supply system and permit it/them to admit fuel alone into the combustion chamber.

The internal combustion engine 10 is provided with an exhaust system 40 and exhaust valving 42 comprising at least one exhaust valve that is operable to release exhaust gases from the combustion chamber 12 into the exhaust system. In the illustrated example, the exhaust system 40 is cooperable with the aqueous fluid supply system 32 to extract heat from exhaust gases flowing in the exhaust system to provide heat used to heat the aqueous fluid that is supplied to the one or more injectors 36. This may, for example, be achieved by having piping through which the exhaust gases flow winding around a pipe or a vessel through which the aqueous fluid flows or flowing the exhaust gases through a vessel containing one or more steam pipes.

The internal combustion engine 10 comprises a controller 48 to control the operation of the first valving 24, second valving 30 and exhaust valving 42. In the illustrated example, the first valving 24, second valving 30 and exhaust valving 42 comprise electrically actuated valves, for example solenoid valves, that are opened and closed in response to electrical command signals issued by the controller 48. In other examples, at least one of the first valving 24, second valving 30 and exhaust valving 42 may include one or more valves that are hydraulically or pneumatically actuated in response to electrical command signals issued by the controller 48 to a source of hydraulic or pneumatic actuating fluid.

The internal combustion engine 10 further comprises one or more sensors 50 connected with the controller 48 to provide the controller with signals indicative of the pressure/temperature in the combustion chamber 12. The one or more sensors 50 may comprise a pressure sensor or a temperature sensor. The one or more sensors 50 may be any suitable type of sensor capable of operating at the relatively high temperatures that will be encountered in use of the internal combustion engine 10. For the purposes of controlling operation of the internal combustion engine 10, at least during some phases of its operation, a temperature sensor needs to be highly responsive to temperature changes taking place within the combustion chamber 12. Where one or more temperature sensors are used, an infrared temperature sensor that senses the temperature in the combustion chamber through a translucent window (not shown) may be used. Alternatively, for example, a high temperature embedded photodiode such as is disclosed in US5 659 133 (the content of which is incorporated herein by reference) may be used.

The internal combustion engine 10 may be provided with a combustion initiator 52 to assist in initiating combustion events in the combustion chamber 12. The combustion initiator 52 may be an electrical combustion initiator such as a glow plug, hot wire, spark plug or the like. The combustion initiator 52 may be connected directly or indirectly with the controller 48 so as to be actuable by the controller.

In Figure 1, the connections between the controller 48 and the valving 24, 30, 42 and the one or more sensors 50 are not shown. This is simply for the sake of clarity of illustration and the skilled person will have no difficulty in envisaging suitable ways and means for making the connections.

In Figure 1, the internal combustion engine 10 is shown comprising just one combustion chamber 12. While this may be appropriate for some applications, typically the internal combustion engine 10 will comprise a plurality of combustion chambers 12, each having a piston 18 connected to the crankshaft 20. In a multiple chamber, or cylinder, engine, the chambers may be arranged in any suitable known configuration such as inline, flat or a V.

Referring to Figure 3, a suitable controller 48 for the internal combustion engine 10 may comprise one or more processors 1600 and signal conditioning components 1602. The signal conditioning components 1602 may, for example, be configured to amplify signals output to the first valving 24, second valving 30, exhaust valving 42, the one or more sensors 50 or the combustion initiator 52, and/or convert analogue signals to digital and digital signals to analogue to permit the controller 48 to receive and use signals from the one or more sensors 50 and output usable signals to the valving 24, 30, 42 and other components of the internal combustion engine 10 that may be controlled by the controller. The controller 48 may additionally comprise one or more random access memories (RAM) 1604 for storing data generated during operation of the internal combustion engine and circuitry 1606 for use in sampling incoming signals from the one or more sensors 50 to provide a usable input for the one or more processors 1600. The controller 48 may additionally comprise one or more data storage components in the form of permanent memory 1608, which may be a read only memory (ROM), in which one or more control software portions 1610 are permanently stored. Of course, for some applications, no permanent memory is required. For example, the controller 48 may be connected with a master computer in which the control algorithms are stored and which uploads them to a RAM in the controller at start-up of the controller. Another alternative would be for the controller to be slaved to a master controller or computer. Yet another alternative would be for the controller 48 to comprise one or more hard wired control circuits.

Referring to Figure 4, an injector 36 is shown mounted in an injector mounting 1700. The injector mounting 1700 comprises a mounting body 1710 fitted to an aperture 1712 provided in the cylinder head 14 and a catalyst 1714. The mounting body 1700 has an upstream end 1716 and a downstream end 1718. The upstream end 1716 is provided with an injector recess 1720 to receive at least an outlet end 1722 of the injector 36. The injector 36 may be secured to the mounting body 1710 by any suitable known means for securing injectors to internal combustion engines.

The downstream end 1718 of the mounting body 1710 is provided with a catalyst holding space 1724 in which the catalyst 1714 is held. The mounting body 1710 is provided with at least one connecting passage 1726, or leading duct, extending between the injector recess 1720 and the holding space 1724 so that, in use, fluid output from the outlet end 1722 of the injector 36 can pass into the combustion chamber 12 via the holding space 1724. There may be one relatively large diameter/width connecting passage 1726 or a plurality of relatively smaller diameter/narrow connecting passages. Having a plurality of relatively small diameter/narrow connecting passages 1726 may enable evaporation of the fluid output by the injector 36 before it reaches the catalyst 1714 contained in the holding space 1724.

The holding space 1724 is defined by a recess provided at the downstream end 1718 of the mounting body 1710 and at least one porous retaining member 1728 provided in the recess to retain the catalyst 1714 in the catalyst holding space 1724. In the illustrated example, there are two porous retaining members 1728 disposed in opposed spaced apart relationship and the catalyst 1714 is held between them. The porous retaining members 1728 may comprise drilled, punched or otherwise perforated metallic sheets or a metallic mesh.

The injector mounting 1700 is provided with means by which it may be secured to the cylinder head 14. For example, the downstream end 1718 of the mounting body 1710 may be provided with a fastening element by which it can be secured to the cylinder head 14. The fastening element may comprise an external screw thread that is engageable with an internal screw thread provided in the aperture 1712. In some examples, the mounting body 1710 may be provided with a groove or slot that is engageable by a fixing plate that may be screwed to the cylinder head 14.

Preferably, the mounting body 1700 is configured such that at least the portion thereof that contains the catalyst 1714 is housed within the cylinder head 14. Thus, the sidewall of the mounting body 1700 where it surrounds the catalyst 1714 is at least substantially disposed within the cylinder head 14. At least where it contains the catalyst 1714, the mounting body 1700 is in intimate contact with the cylinder head 14 to facilitate the conduction of heat from the cylinder head into the mounting body. A heat conducting paste may be provided between the mounting body 1700 and cylinder head 14.

The mounting body 1710 is made of a metal that is a good heat conductor and may, for example, be made of the same metal as the cylinder head 14. In some examples, the mounting body 1710 may be made of one of the following metals:

Metal Thermal Conductivity W/m.K

Brass 150

Tungsten 174

Aluminium 237

Copper 386

In use, a fuel and aqueous fluid are supplied to the injector 36 from the aqueous fluid supply system 32 and the reservoir 34. The blend or mixture of aqueous fluid and fuel supplied from the injector 36 passes through the connecting passages 1726 and into the holding space 1724. The blend may be at least partially vapourised in the connecting passages 1726 and absorbs heat from the cylinder head 14 via the mounting body 1710. The heat from the cylinder head 14 absorbed by the aqueous fluid/fuel mixture in the holding space 1724 in the presence of the catalyst 1714 causes a steam reformation process by which hydrogen is separated from at least one of the fuel and the aqueous fluid.

In some examples, the fuel supplied to the injector 36 is selected to facilitate steam reformation and a different fuel may be supplied to the combustion chamber 12 for the main combustion event in each cycle. In such examples, the different fuel may be supplied through a separate dedicated injector or injectors.

Housing the catalyst 1714 in a holding space 1724 outside of the combustion chamber 12 may protect the catalyst 1714 and the reaction it promotes or enhances from oxidation due to exposure to oxygen. The heat that is required to be absorbed by the catalytic reaction, and by the evaporation process, is mainly absorbed through the cylinder head 14 that is connected to the mounting body 1710. This may reduce the cooling requirement for the cylinder head and improve the overall thermal efficiency of the engine by reusing heat that would otherwise be conducted away from the combustion chamber 12 or cylinder head 14 by the coolant flow.

The tables below show some possible desired relative properties of a mounting body such as the mounting body 1710 shown in Figure 4.

It is to be understood that although the injector mounting 1700 has been described in connection with a reciprocating piston internal combustion engine, the concept may also be applied to Wankel engines. It will be understood that by providing the catalyst in an injector mounting such as the injector mounting 1700, it is possible to retrofit to existing engines and allow the operation of an engine cycle that includes the production of hydrogen by steam reformation in legacy engines not designed for onboard hydrogen production. For example, the injector mounting 1700 may be configured to fit in an opening in a cylinder head that has been configured to receive a conventional injector and secured to the cylinder head by the same means as the conventional injector.