BACKGROUND ART Principles of the present invention will be discussed in relation to a method of manufacturing internal combustion engines such as those commonly used in motor vehicles. It should be appreciated however that the principles of the present invention can apply to the manufacture of other engines.

Present methods of manufacturing an engine block is to either sand cast, die cast or investment cast iron (or more recently aluminium).

These processes are complicated, expensive, labour intensive and places limitations on the design of the engine block.

Sand casting involves the placement of a mould (generally wooden) into casting sand which is packed around the mould. The mould, and hence the engine eventually manufactured, must be tapered to allow ready removal of the mould from the packed sand. It should be noted that the sand mould may include inserts for more complicated parts of the engine design.

Once the mould is removed, iron (or sometimes aluminium) is then poured into the sand mould. Once the metal has cooled sufficiently, the sand mould is broken and the rough engine cast removed.

Next, the engine block has to be machined considerably to provide smooth surfaces. An alternative to machining the inside of the cylinders is the inclusion of a cast iron sleeve.

Engines are also heavy because they are generally cast in full form with all of the cylinders at one time, or at least half of the cylinders if the engine is a V6 or V8.

A typical engine block is through the nature of the casting process extremely heavy due to the limitations of the casting process requiring thicker walls, and has a large number of parts or add ons that cannot be provided through the moulding process.

The destruction of the mould inserts every time a block is manufactured is expensive. Also expensive is the labour required to provide the extra machining and incorporation of additional parts.

Limitations of the design of an engine block formed by a casting process means that dead ends are included in the water jackets of the engine block.

This restricts the flow of cooling fluid through the engine and thus reduces the efficiency of the engine.

A number of these problems are present in die casting and investment casting methods also.

Another problem is that the complicated nature of engine design required for these methods means that manufacturers are reluctant or slow to change to more advantageous engine designs because of perceived difficulties.

It would be desirable if there could be provided a method of engine block manufacture that overcomes these problems.

It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.

Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.

DISCLOSURE OF INVENTION According to one aspect of the present invention there is provided a method of manufacturing an engine block characterised by the steps of: a) extruding a length of material to form at least part of an engine block, and b) cutting the length of material when it reaches the desired length for said engine block part.

The process of extrusion is one not normally thought of when looking at engine manufacture. This is because the current design of engines is such that it would be difficult to apply the extrusion process. Present designs do not have the substantially constant cross section required for extrusion.

The applicant has recognised that a new engine design could enable at least part of an engine to be produced by the extrusion process with all of its advantages.

It is envisaged that standard extrusion processes can be used with the present invention.

In preferred embodiments of the present invention the extrusion process is applied to engine designs having side valves. In particular, the applicant has designed a new side valve engine as detailed in New Zealand Patent Application Nos. 314113 and 299841.

It should be appreciated however that the present invention can apply to engine blocks having alternate designs. For example, an engine block may be constructed using the above method which employs poppet valves, as opposed to piston valves.

In preferred embodiments of the present invention the portion of the engine which is extruded includes the main piston cylinder, cylinders for side piston valves, water jackets surrounding the cylinders and, if appropriate, cooling fins.

A single main cylinder and side cylinder"block"may be manufactured by the extrusion process, or in alternative embodiments a whole engine block with multiple cylinders may be extruded at one time.

One advantage of extruding single cylinder blocks as opposed to a whole engine is that the extrusion process is considerably easier. For example, the extrusion has less material and less mass and thus is easier to handle in terms of sheer size and weight and the extrusion forces required.

Further, the less mass there is, the less restrictions there has to be made on the extrusion design to ensure that there is minimal distortion of the extrusion during the cooling process.

Even so with the extrusion process, considerably tighter tolerances can be obtained with extrusion than with casting.

Obviously, if the cylinders are extruded singularly, then there must be provided a means by which they can by joined together to form a single engine.

Means of attachment may be through a conventional method such as bolts, brackets, welding, and so forth.

However, in preferred embodiments the extruded cylinder is made so that it has complimentary lugs and indentations, readily allowing the individual extrusions to fit readily together.

In particular, it is envisaged that an interlocking connection such as that either a dove tail or tongue and groove arrangement would be employed.

These arrangements have the advantages in that they can be readily incorporated into an extrusion and that the engine is secured over the whole depth of the block rather than just at point sources.

The engine may be made out of a variety of materials, for example conventional materials such as iron and aluminium or even KevlarTM reinforced aluminium.

Plastics, composites and ceramics may also be used depending on the working parameters of the engine. For example, it may be possible that the design of an engine produced in accordance with the present invention runs sufficiently cool that plastics material can withstand the heat generated.

One advantage of the present invention is that the length of the engine block can vary according to the capacity required for the engine.

For example a three litre engine may have the same cross-section as a two litre engine, but just be 50% longer. This is a remarkable achievement which provides a startling degree of uniformity not previously found in engine manufacture. It should be appreciated with traditional cast manufacturing methods that different capacity engines have quite different design moulds, along with the added features. The present invention ensures that there is uniformity of design and thus efficiency in the manufacturing and management process.

Another advantage of the present invention is that apertures can be extruded which run through the engine block. This provides a single locking system that enables the sump and engine head to be readily bolted onto the extruded block using bolts which run through these apertures.

This is in contrast to traditional methods of manufacture which had individual connections of the sump to the block and of the head to the block.

It should be appreciated that this locking together of the three main components of the engine using a single locking system such as tie rods or bolts ensures that an extremely strong structure is produced. This strong structure means that a material weaker than iron-such as aluminium can be used.

It should be appreciated that aluminium will reduce the weight of the engine by approximately 40% as compared to cast iron engine.

A comparison of possible materials that can be used with the present invention besides past materials used is given below. It can seen that the present invention allows for lighter more easily worked material to be used. Cast Engine Present Invention CapitalCosts: Plant & Machinery cost to produce Plant & Machinery for 200mm and 100 engines per hour is $100m. bigger extrusions-$5-10m to ($1m/engine/hour). produce +1000 engines/hour. Each ASME by Robert J. Perry, new engine design cost for die only. Automated Machine Division of Babcock & Wilcox, C322/73 EnvironmentalPollution: Iron casting furnaces need Coking No toxic fumes Coal of which there will be a world No Smelting at the extrusion plants shortage. Burning of Coal produces No waste-completely recyclable. 'Cupola emissions'-an environmentally disastrous gas. Design & Product life expectancy: Cast Engines-5 years from initial design to production. 10-15 years Design to full production is very fast production life (due to high initial 6-8 weeks (time it takes to cut the capital costs). die). Designs can easily be changed -very low production costs. Cast Engine Present Invention DimTolerances: Thin wall castings average thickness Average thickness 4.5mm 4.75mm. Tolerances +/-0.33mm Tolerances +/-0.813 Final overall thickness 4.5mm Final overall thickness 3.81 +/-0.33 (+0.76/0.38) Alloys: Hypereutectoid Aluminium Silicon 6261/6351 alloys 0.7% Silicon 390/336 0.4% Copper 16-18% Silicon 0.35% Manganese 4-5% Copper 0.2% Titanium Ultimate tensile strength-295 MPa Can be Anodised Weights: Mitsubishi Evo-3-4 Cyl/2 Litre Power Beat Piston Valve Extruded Engine : Engine : Cast Iron Block 4 Cyl/2 Litre Engine Cast Alloy Head w/twin OHC Extruded Alloy Block, Sump, Head Cast crank, rods & pistons Piston Valves 87.2 Kg's Cast crank, rods & pistons 53.5Kg's Cast Engine Present Invention Cooling: Considerable problems with the Superior cooling with internal fabrication of the cooling core. cooling fins in the block in addition to the heat sinks on the sump and head.

The entire engine block may be configured with separate sump and head portions for each cylinder or, there may be a common sump and head for all or some of the cylinders.

It is envisaged that the sump may also include the crank shaft and main bearings of the engine.

It should be appreciated that a single extrusion tool can be used to make variable capacity cylinders in an engine block.

It is believed that the extrusion process will minimise the amount of machinery required on the engine block. Thus, it may be possible that the cylinder wall may not need to be machined or that a sleeve need not be inserted into the cylinder.

In some embodiments however, a hardened plastic cylinder block may be extruded including cooling fins surrounding the cylinder. Metal sleeves may in this embodiment be inserted into the block to form the engine cylinders.

The metal sleeves may be configured to absorb and manage most of the waste heat generated in the cylinder which may be radiated to cooling fins surrounding the cylinder.

Following extrusion, the engine block may be readily liquid treated on- account of its flow-through characteristics resulting from the extrusion process. For example, the engine block may be readily anodised.

Anodising the inside of the cylinders can protect the cylinder wall from wear and tear. The applicant has recognised that if the anodised coating is coloured, the amount of wear and tear in the cylinder wall can be gauged visually. It is also possible to use other coating methods already used in cost aluminium engines.

In some embodiments, the cylinders will be machined after extrusion and then coated-perhaps with a hard chrome or NikasilTM treatment.

The flow-through design of the present invention also enables superior cooling systems to be used in relation to the engine.

For example, in some embodiments no dead ends need be incorporated into the water jacket as with a traditional cast iron block. Instead, the cooling fluid can flow from the head past the cylinder and into the sump.

Circulation of the cooling fluid through the sump may also cools the engine oil.

The extrusion of the engine block allows thin walls of uniform thickness to be produced which results in a larger volume of free space surrounding each cylinder which in turn enables greater heat transfer from the engine.

Further, a low strength coolant pump need only be used as there is less requirement to force fluid through the engine.

Other componentry making up the engine may also be extruded. Typically some of the additional componentry such as hte sump was bolted to the cast engine block. This is an inherently weak connection.

While the present invention in preferred embodiments uses tie-rods to hold the major components together, an additional connection means may also be employed which can also assist in the assembly of the engine.

In one embodiment this additional connection means may be dowelling sleeves which can fit in apertures between the components and serve to align and secure the components to each other. The tie rods may pass through these sleeves.

One advantage of having extruded componentry is that fluid passages such as oil ways can be readily extruded. This is in stark contrast to previous processes which involved a complicated and time consuming machining process to create the fluid passages.

It should be appreciated that additional cooling such as provided by the present invention improves considerably the engine efficiency and reduces wear and tear.

It should be apparent that the present invention has a number of advantages over the prior art. These advantages include: a) an efficient manufacturing process b) reduced machining required c) cheaper tools such as those used in the extrusion process d) less waste as separate mould and inserts are not destroyed every time an engine block is produced e) the design of the engine block does not have to be tapered to be removed from the mould f) less parts are involved in the manufacture of the engine thus making the engine block quick and easy to assemble g) a single extrusion tool may be used to make variable capacity cylinders and engine block involving a variable number of cylinders h) improved flow characteristic of the cooling fluid allows a low strength pump to be used to circulate the cooling fluid i) the ability to use alternate materials to cast iron means that the engine can be lighter in weight-which amongst other things gives easier handling and greater power to weight ratios.

BRIEF DESCRIPTION OF DRAWINGS Further aspects of the present invention will become apparent from the following description which is given by way of example only and with reference to the accompanying drawing in which: Figure 1 is a perspective view of a single cylinder block made in accordance with one embodiment of one design of the present invention, and Figure 2 is an alternative design of a single cylinder block in accordance with one embodiment of the present invention, and Figure 3 is an extruded engine head which can be used with the cylinder block shown in Figure 2, and Figure 4 is an extruded sump which can be used with the cylinder block shown in Figure 2, and Figure 5 is an extruded sump cover plate engine head which can be used with the cylinder block shown in Figure 2, and Figure 6 is an exploded view of an assembled four cylinder engine using the componentry illustrated in Figures 2 to 5, and Figure 7 is a table outlining some of the perceived advantages of the present invention, and Figure 8 is an exploded view of an alternate design of the present invention.

BEST MODES FOR CARRYING OUT THE INVENTION Figure 1 is a diagrammatic perspective view of a single cylinder block generally indicated by arrow 1.

The cylinder block 1 has been designed to have a substantially constant cross section to readily allow the block 1 to be extruded.

It can be seen that the cylinder block 1 has minimal additional machining, namely the bolt holes 2 and exhaust and inlet ports 3 and 4.

The cylinder block 1 has a main cylinder 5 and two side cylinders 6 and 7.

In preferred embodiments of this invention the cylinders 5,6 and 7 are anodised.

Surrounding the cylinders are water jackets 8 and 9 which allow cooling- fluid to travel from the head of the engine (when assembled) down to the sump.

Protruding into the water jacket 8 are cooling fins 9 which act to transfer heat from the exhaust cylinder 7.

The design of the cylinder block 1 has been constructed to provide a number of channels and plugs which enable the individual cylinder blocks to be fitted together with a dove tail arrangement. These channels and lugs are indicated by arrows 10.

In addition, bolt holes 11 have been provided which enables the engine cylinder block 1 to be readily bolted to the sump (not shown) and the head (not shown) of the assembled engine.

It can be seen from Figures 3 to 5 that other componentry in addition to the engine block can be machined as well.

Figure 3 shows an engine head which has its underside (not shown) machined to provide a combustion chamber.

Figure 4 is an illustration of a sump.

Figure 5 is an illustration of a sump cover plate.

The workings of the exploded four cylinder engine shown in Figure 6 should be readily apparent to one skilled in the art and therefore a table of the various componentry is given below. Component Reference Number SparkPlug 20 Extruded Engine Head 21 TieRods 22 ExhaustManifold 23 InletManifold 24 Main Piston Head 25 Side Piston Valve Heads 26 Main Piston Con Rod 27 CrankShaft 28 Extruded Engine Block 29 ExtrudedSump 30 Extruded Sump Cover 31 DowelSleeve 32 OilWay 33 Figure 7 is a table outlining some of the perceived advantages of this invention.

Figure 8 is an alternate design of an engine block which includes cooling fins 34.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof as defined in the appended claims.