This invention relates to an engine.

Most engines use pistons, connecting rods, and a crankshaft. Such engines are difficult to balance and generate considerable internal friction losses. Turbines engines on the other hand are very expensive to make and offer very poor throttle response.

An aim of the present invention is to provide an engine which has rotating parts which can be perfectly balanced, and which is such that it generates minimal internal friction losses, and offers a high power/weight ratio and excellent low-end torque.

Accordingly, in one non-limiting embodiment of the present invention there is provided an engine comprising a power section where gas is expanded, with inlet means for air and fuel, and outlet means; a central output shaft on which is mounted at least one rotor rotated by pressure applied to the rotor surface, and a plurality of variable-volume chambers with their volumes part-bounded by members attached to arms attached to oscillating outer shafts extending parallel to the central output shaft, and the engine being such that the oscillating movement of the outer shafts is controlled by arms with parts co-operating with at least one cam profile rigidly fixed to the central output shaft.

The engine of the present invention may be constructed to be free of conventional pistons, connecting rods and a crankshaft, and therefore the

engine can operate much more smoothly than known engines that are dependent on the use of a crankshaft. The compressor may operate to provide required compressed air in a direct manner, or in an indirect manner via a buffer chamber. If desired, exhaust gases from the engine may be re- circulated. The use of the rocking arms causes substantially no or very little sliding friction, thereby enabling the engine to operate with improved efficiency. The use of the arms co-operating with at least one cam enables rotary motion to be converted to oscillating motion, and vice versa.

The members may move in arcuate paths.

The engine may be such that the members are vanes. The rotor may abut a cylindrical housing at its nearest contact point, causing two consecutive chambers of varying volume to be formed either side of this area. In addition to these chambers, the engine has other chambers which are from time to time not subdivided.

The engine may be one in which combustion takes place in the variable-volume chambers in the combustion module, with the variable- volume chambers being bounded by the housing, the vanes and a rotor surface. Gas expansion may take place in the variable-volume chambers in the compressor module, with the variable-volume chambers being bounded by the housing, the vanes and a rotor surface.

The vanes may touch the rotor surface. Alternatively, the vanes may not touch the rotor surface. Alternatively, the vanes may have rollers which roll on the rotor surface.

In an alternative embodiment of the engine of the present invention, the members are pistons. The engine may then be one in which combustion takes place in the variable-volume chambers, the variable-volume chambers being chambers in which the pistons operate. Gas expansion may take place in the variable-volume chambers, the variable-volume chambers being chambers in which the pistons operate.

In all embodiments of the invention, the compressor may be driven directly or indirectly by the central output shaft. Alternatively, the compressor may be such that it is not driven by the central output shaft and, in this case, the compressor will normally be driven by an indirect power source which may be an external one.

The engine of the present invention may include a buffer chamber connected to the compressor and the power section.

The engine may be one in which the arms co-operate with the cams via roller means, the cams being mounted on the central output shaft. Alternatively, the arms may co-operate with the cams, the arms being such that they do not have roller means.

The engine may be such that it has three outer shafts, the outer shafts being three equally radially-displaced outer shafts which extend parallel to the central output shaft. The three outer shafts may oscillate out of phase with each other. Pairs of arms rocking on the three outer shafts may rock out of phase with each other. When the three outer shafts oscillate out of phase with each other, then the rocking motion of all three outer shafts may be controlled by one pair of cams. The rocking motion may also

be controlled by one cam. When the engine comprises pairs of arms rocking on the three outer shafts which rock out of phase with each other, then the rocking motion of the pairs of arms may be controlled by more than one pair of the cams. This rocking motion may also be controlled by single cams.

The engine may include a plurality of power sections. Some of the power sections may work out of phase with others of the power sections.

The engine may include a plurality of compressor sections.

The cams may be conjugate cams. Thus the engine may comprise one cam working with another cam as a conjugate pair.

The engine may be one in which the power sections also act as compressors.

The various components may be made of any suitable material. The surfaces of the components may have coatings, for example ceramic coatings.

Embodiments of the invention will now be described solely by way of example and with reference to the accompanying drawings in which;

Figure 1 is a schematic view of a first engine of the present invention, the engine comprising a power module, a buffer module, a compressor module, and a conjugate cams module;

Figure 2 shows an end plate which is on the left side of the conjugate cams module as shown in Figure 1 ;

Figure 3 shows in detail components of the conjugate cams module;

Figure 4 shows a wall plate which is situated on the right of the conjugate cams module as shown in Figure 1 ;

Figure 5 shows a section through the left side of the compressor module as shown in Figure 1 ;

Figure 6 shows a section through the middle of the compressor module as shown in Figure 1 ;

Figure 7 shows a section through the right side of the compressor module as shown in Figure 1 ;

Figure 8 shows a wall plate located on the left side of the buffer module shown in Figure 1 ;

Figure 9 shows the slot control disk in the buffer module shown in Figure 1 ;

Figure 10 shows a wall plate located on the right side of the buffer module shown in Figure 1 ;

Figure 11 shows a section through the left side of the power module shown in Figure 1 ;

Figure 12 shows a section through the middle of the power module shown in Figure 1 ;

Figure 13 shows a section through the right side of the power module show in Figure 1;

Figure 14 shows the wall plate located at the right hand side of the power module shown in Figure 1 with a rotating disk abutting it; and

Figure 15 shows a wall plate like that shown in Figure 14 but with all exhaust holes uncovered.

The engine comprises a housing having a series of plates 1, 2, 3, 4, 5 which are separated by hollow spacers 6, 7, 8, 9. The plates and the spacers are secured together by a plurality of nuts 11 fixing on bolts 10 which pass through holes 14. The engine is in various sections which can be regarded as separate modules. Through all of the modules runs an output shaft 12 which is located in bearings 13, and three outer shafts 15 which are located in bearings 16.

(a) The Power Module

A rotor 42 is mounted on the output shaft 12. The rotor 42 rotates inside a cylindrical housing spacer 9 forming variable-volume chambers 43, 44, 45. The rotor 42 preferably rotates with a few microns of clearance, thereby avoiding friction losses and any need for lubrication. This is a trade¬ off against some blowby losses. However, in an alternative embodiment, it may be preferable to fit moving shoes 32 to vanes 28 as shown for sealing purposes with minimal contact pressure. The rotor tip 35 may also touch the spacer 9 for sealing purposes.

The vanes 28 are attached to arms 47 locked to the three parallel outer shafts 15. The vanes 28 are deployed to form the separating walls of the variable-volume chambers 43, 44, 45. It is important to note that the vanes 28 are not sliding vanes. The vanes 28 are pivoting rocking vanes. The major thrust loads on the vanes 28 are taken by the bearings 16 for the outer shafts 15.

As the rotor 42 rotates, a succession of variable-volume chambers is formed. Each one of the variable-volume chambers is bounded by the cylindrical wall, rotor surface, at least one vane and sidewalls. Advantageously, there does not need to be any actual contact between the fixed and moving chamber parts. So, again, there are no frictional losses other than generated by rubbing seals 30 and other seals if these are fitted. Rollers running on the cam surfaces in the conjugate cams module accurately-position the vanes with simple harmonic motion as they ultimately control all vane movement.

As the rotor 42 rotates, compressed air is admitted through inlet ports 41 from the buffer chamber. Fuel, injected through a direct injector 46, then burns. This causes a rapid pressure increase which turns the rotor 42 clockwise. The air flow through the inlet ports 41 is controlled by a disk 39 which is locked to the shaft 12. The shaft 12 rotates in the buffer chamber which is bounded by the wall plates 3, 4 and the spacer 8. The disk 39 abuts plate 4 and has a slot 40 in it. The slot 40 lines up with the ports 41. The disk 47 is locked to the output shaft 12. The other disk 47 locked to the output shaft 12 determines when the exhaust ports 48 are uncovered. This process usually starts when the positive turning moment in a chamber dwindles and, if the ports were not open, a negative turning moment would result.

As the tip 35 of the rotor 42 sweeps through each of the three sectors bounded by the rotor surface, vanes, sidewalls and housing, the rotor 42 is double-acting. As some rotor surfaces are being pushed by combustion

pressure, the other rotor surfaces are expelling the combustion products of the previous combustion stroke through the outlet ports 48 in the plate 5 to join the exhaust stream. There is no fluid movement reversal. If exhaust gas re-circulation is desired, for example to lower combustion temperatures and thus the formation of NOx, some of the exhaust gases can be sent to the buffer chamber. The amount of the exhaust gas sent back to the buffer chamber is easily regulated.

Each of the three sectors contributes one power stroke and one exhaust stroke for each revolution of the output shaft without any gearing. The power density may be better than state-of-the-art two-stroke engines.

In one embodiment of the present invention, the "torque curve" is flatter because the three power strokes are out of phase. If three power modules work out of phase with each other, only the number of power modules that are required need to be deployed. For example, in an automobile engine, just one power module would need to be deployed for freeway cruising, two for normal use, and three for very fast acceleration.

The engine of the present invention may be of various designs and all of these various designs of the engine are easily started at any degree of rotation of the output shaft. Thus the engine is far better suited to stop/start conditions that conventional engines. The expense, weight and current drain of a normal starter motor can be saved.

Induction + compression strokes and compression + exhaust strokes may be provided in separate modules. Larger valves mean flow rates can

be much higher. A number of different types of air compressor can be used for the compressor module.

Conventional liquid cooling may or may not be needed for the engine. If conventional liquid cooling is needed, then it may be provided for by adding appropriate cooling modules. Emission considerations aside, ceramic coatings may allow the power module to run near-adiabatically. Some of the energy in the exhaust stream can also be recovered. Water vapour injection, which is easily provided for, may both lower temperatures and increase power output. The cleaning up of start-up arid transient condition emissions is easier with the engine of the present invention than with many known engines.

(b) The Compressor Module

The compressor module provides the induction and compressor function of the engine. More specifically, the compressor module supplies clean high pressure air (free of any exhaust gas re-circulation at this stage) to the power module. The supply of the clean high pressure air may be direct or it may be via the buffer chamber 3, 4, 8, where intercooler technology can be employed.

The compressor module features three variable-volume chambers 24, 25, 26. Each one of the three variable-volume chambers 24, 25, 26 is circumscribed by a circular wall of part 7, the vane arms 27, the vanes 28, vane shoes 32 if fitted, a surface of the rotor 36, and sidewalls 2, 3. The vanes 28 may or may not need to run between seals 30. The vanes 28 are

attached to arms 27 attached to the oscillating shafts 15. The housing 7 has spaces 29 for the arms 27 to retract into.

As the rotor 36 rotates in a clockwise direction, air gets sucked into chambers 24, 25, 26 when each is expanding, through their respective inlet ports 33a, 33b, 33c. Each inlet port 33a, 33b, 33c has preferably a spring- biased flap 34a, 34b, 34c respectively which closes when the pressure inside the respective chamber 24, 25, 26, exceeds the pressure in the inlet port. The air in the chamber 24 gets compressed by the rotor 36, starting from when the volume of the chamber changes from increasing to decreasing. The air in the chamber 24 exits through a one-way valve 38 in the outlet port 37 in the wall plate 3, similarly with other chambers.

The rotor 36 is double-acting so that while air is being sucked into the chamber immediately one side 36a of the rotor tip 35, air is also being expelled from the chamber immediately the other side 36b of the rotor tip.

The three chambers 24, 25, 26 operate out of phase. Figure 5 shows the volume of chamber 24 increasing and the position of flap 34a, the volume of chamber 25 decreasing and the position of flap 34b, and the volume of chamber 26 near or on the turn and the position of flap 34c.

The profile of the rotor 36 is the same as that of the cam 18. The shoe 32, if fitted, pivots around a point 31. This point 31 in each case is on the axis of the roller 20 running on the cam 18. The contact points of the shoes 32 will gradually wear as the presented shoe profile changes. The shoes 32 may thus not be fitted if desired, in which case vane ends with the roller profile may alternatively be employed. The chambers 24, 25, 26 do

not need to be the same width as the power chamber 43, 44, 45. The chambers 24, 25, 26 can be longer or shorter. Additional air can be supplied to the buffer chamber.

(c) The Conjugate Cams Module

The conjugate cams module features conjugate cams. As shown, the conjugate cams mechanism converts rotary motion in the drive shaft 12 to simple harmonic oscillating motion in the outer shafts 15. The same arrangement works vice versa, and is primarily used this way in a second engine of the present invention, described later.

Figure 3 shows a side view looking at the conjugate cams etc. inside the spacing ring 6. Two cams 17, 18 are mounted on a straight drive shaft 12. The two cams 17, 18 each have a different peripheral cam profile. Also mounted on the straight drive shaft 12 is a balancing weight 19. The two cams 17, 18 and the balancing weight 19 form a perfectly balanced rotating mass. Rollers 20, 22a run on the peripheries of the two cams 18, 17, respectively. The rollers 20, 22a rotate on pins 21 , 22b respectively located on rocking arms 23, 22 respectively. The rocking arms 23, 22 are mounted on three shafts 15 parallel to the output shaft 12.

For each rotation of the output shaft 12, each of the shafts 15 rotates 30° clockwise and then 30° anti-clockwise with simple harmonic motion. The three shafts oscillate out of phase.

The rotating conjugate cams 17, 18 co-operate with the two rollers on each of the three pairs of arms to generate simple harmonic motion arm

movement. In each case, one of the rollers 20 runs on one cam 18, with the other roller 22a running on the other cam 17. Each roller 20, 22a always rotates in the same direction. Each roller working in a pair precisely controls the location of the other roller. There is a critical fixed spatial relationship between the rollers 20, 22a. There is no scuffing. Unlike in conventional piston engines, the rotating assembly in the engine of the present invention can be perfectly balanced. It may also serve as a flywheel. It may feature an integrated starter-alternator.

(d) Second Engine

A second engine of the present invention may use powered simple harmonic motion-oscillating shafts to deliver rotary motion to the output shaft. This is easy to achieve by attaching single or double-acting paddle- pistons to the arms, in this case just to the longer roller-carrying arms. Thus the shafts can be made to oscillate putting pressure on the rollers to turn the cams. The pivoting paddle-pistons describe arcs. The pivoting paddle- pistons may move 30° one way, and 30° back. Again, the three oscillating shafts operate out of phase for a flatter torque curve. High loads may induce high contact stresses. The friction losses at the roller/pin interfaces may be unacceptable for automotive powertrain applications. However, for many applications this simpler engine could be better.

The oscillating shafts 15 can be used to power a compressor which uses paddle pistons or round pistons. This alternative can be interfaced with the aforementioned buffer chamber.

It will be appreciated from the drawings that the illustrated engines of the present invention can be produced as a range of smooth high-power engines. The smooth operation is largely due to all the rotating parts being perfectly balanced. The engines can be started at any degree or rotation of the output shaft. The engines are able to offer very high torque at all times, coupled with instant throttle response. The manufacture of the engine in modular parts facilitates the easy and cost-effective production of the engine, and also the recycling of parts. Fluid flow from the engine may result in less environmentally-unfriendly emissions per kilometer than with known comparable engines. Similarly, acoustics should be better than, for example, generators, with substantial noise-cancellation being possible with the engine of the present invention.

It is to be appreciated that the embodiments of the invention described above with reference to the accompanying drawings have been given by way of example only.