GB2227522A

GB2227522A - Opposed piston twin crankshaft I.C. engine

Info

Publication number: GB2227522A
Application number: GB8901895A
Authority: GB
Inventors: Terence Joseph Kelleher
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-01-28
Filing date: 1989-01-28
Publication date: 1990-08-01
Also published as: GB8901895D0

Abstract

The crankshafts of the two pistons are connected to rotate in unison with one piston reciprocating in advance of the other. Maximum combustion pressure occurs when the one piston is past top dead centre in a position to maximise crankshaft torque. The engine may be a two or four-stroke with spark or compression ignition. <IMAGE>

Description

Dual Torque Opposed Piston Internal Combustion Engine This invention relates to an internal combustion engine.

The conventional well known internal combustion engine,whether petrol, diesel, two stroke or four stroke, generally works on the reniprocating piston principle. Motive power to the piston is caused by the detonation of an air-fuel mixture, the action of the piston transmitting rotary movement to a crankshaft via a con rod. This movement although simple is geometrically inefficient.

With reference to Fig. Ia,it can be seen that the initial power force taking place with the piston towards the top of the stroke ,has a very reduced resultant torque (F x rI). As the piston moves down, the radius increases until maximum resultant radius at the tangential position (F xr2), but where the combustion force is beginning to dissipate. As the piston moves still further down into the lower segment both motive force and resultant radius reduce to a stage where very little useful power is produced. (Fx r3).

It can be seen therefore that if the combustion force could be made to work either side of the tangential radius , within a confined segment, almost the best possible torque situation could be achieved.(Fig Ib ).

With the conventional engine, if the detonation point acted on the piston with the crank at this ideal angle, the piston would have lowererd to a position from the TDC., so enlarging the.combustion chamber that the fuel compression would have been lost.

The ideal situation therefore,is if this crank segment could be reached, with the correct volume still bing achieved in the combustion chamber.

The initial detonation ,also acting on the ideal crank position would also benefit by a very increased inertia effect.

According to the invention there is provided an engine system where, in a single cylinder engine there is a common cylinder inside which is housed a pair of opposed pistons. Each piston is connected via a con rod to seperate crankshafts, situated at either end of the cylinder. The pistons, which are refered to as 'primary'and'secondary have their respective crankshafts driven together by means of a transmission system nr) that they rotate together in unison, the piston stroke positions, threfnre be in" continuously related to each other.

F1g.? shows the sequence of the system during one cycle of the crankshafts.

With the secondary piston at TDC. ,the explosion on the power stroke is delivered to the primary piston with its crank position at the beginning of its ideal angular segment. At that point the bsocondnry piston, beinp at TDp.is unyielding and furl power is delivered to the primary piston.

AS the primary piston is for are down zrnducinp maximum torsue, the secondary piston is driven round , being assisted by the opposing detonation force on its nisto.As the primary crankshaft nears the end of its ides segment, power is transfered to the secondary crankshaft, due to the fact that the still expanding gases are now acting on the secondary piston with its crank now also positioned at the start of its ideal angular segment. This piston continues the power stroke, in turn producing maximiur torque to its crsnkshaft untill the priory srankshaft reaches 3DC.

At this point the secondary crank is now also towards the end of its ideal segment, and the driving torque starts to decay. The still expanding gases however continue to exert force to the secondary piston which still transmits a rotary movement to its crankshaft.

At this point in the cycle there is a short period where the pistons are both moving in the same direction, but the volume between them still increasing slightly due to the angular positions of their respective cranks. As the secondary crankshaft rotates past its 3DC., the opposing pistons start to close together once more, to eventually produce a minimum volume condtion.An interesting feature of this system, that can be used to advantage, is that this minimum volume condition moves from secondary side to primary side before the cycle restarts.

The invention also allows for other desirable features to be satisfied: Due to the combined movement of the opposing pistons in the same cylinder, their individual strokes can be reduced to still maintain the required maximum compression ratio.

With a bore to piston length ratio maintained ,the compression ratio can be achieved using minimum capacity pistons,their mass reducing the generation of stress to the con rod and main bearings.

Although not essential the design lends itself to the use of sleeve valves, -which could allow for fast induction and exhaust conditions, giving the possibility of higher compression ratios , or lower octane fuel usage.

As with the conventional engine , cylinders can be employed in multiples, to even out pulsation effect, obtain ballance and increase power.

These features could be beneficial to where the invention is employed as an internal combustion engine, whether petrol, diesel,two stroke or four stroke.

According to the invention: The Dual Torque Opposed Piston Internal Combustion Engine applied as: a Four Stroke. (Petrol) As with the conventional four stroke engine, one complete cycle consists of two revolutionsOReferenee to Fig.3 shows the sequence of the first revolution and Fig.4 , the second.

3a- Secondary crankshaft/piston at TDC.

Primary crankshaft/piston at start of ideal angular segment at ignition stage. Both valves closed.

3b- Combustion forces primary piston down,rotational drive being transmitted to the secondary crankshaft,untill it reaches its ideas segment when power is transferred.Both valves still closed.

c Secondary crankshaft/piston at BDC.

Primary pistop,.ret,rning to reduce volume. Gases start to escape out of open exhaust valve.Tnlet valve closed.

3d- Primary piston at TDC.

Secondary piston closes to produce minimum volume condition, forcing exhaust gases out of open exhaust valve.

The second revolution: 4a- Minimum volume condition transfers to primary side.

Secondary crankshaf/piston at TDC.

Primary cranks haft/piston at start of ideal segment at induction stage.Exhaust valve closed,Inlet valve open.

4b- Primary piston and secondary piston retract to induce in the air / petrol mixture. Exhaust valve closed, Inlet valve open.

4ck Primary and secondary pistons move together as the crankshafts rotate. Both valves closed.

4d- Primary piston at TDC.

Secondary piston closes to produce minimwn volume condition, cmpressing the fuel mixture on the secondary side before transsferring to the primary side, where the complete cycle will re-start.

According to the invention: The Dual Torque Opposed Piston Internal Combustion Engine applied as aaTwo Stroke.(Petrol) -crankease scavanged.

As with the conventional two stroke engine, one complete cycle consists of only one revolution. Reference to Fig. 5 shows the sequence.

5a- Secondary crankshaft/piston at TDC.

Primary crankshaft/piston at tart of idea) angular segment at ignition stage. Transfer and exhaust ports closed, inlet port exposed,allowing air fuel mixture to be drawn in.

5bl Combustion forces primary piston down, rotational drive being 5c transmitted to the secondary crankshaft, until it reaches its ideal segment when power is transferred. Transfer, exhaust andinlet ports closed, with the descending piston on the secondary side, compressing the fuel mixture in the crankcase.

5d- Secondary crankshaft/piston at 3DC.exposing a transfer port to allow the pre-ompressed mixture into the cylinder,and exposing an exhaust port, allowing ths exhaust gases to escape.

Se- Primary piston nt TDC.

Secondary piston closes tn produce minimum volume condition, compressing the fuel mixture on the secondary side beforp trsnsferr- inp to the primary side, where the complete cycle will start.

All ports are closed until that point.

According to the invention: The Dual Torque Opposed Piston Internal Combustion Engine applied me a Two Stroke. (Petrol)- Blower Pump.

Another virsion of the conventional two stroke in existance is where tha crankease is not lzsed in the fuel mixture compression cycle,but mixture is forced into the cylinder by means of an external pump system.

The invention can be applied to an engine of this type, whereby the numbers of ports are reduced to two, the inlet and exhaust.The exhaust port would be positioned as previosly described Figs. 5, and the inlet would be positioned qt the previous transfer abort Do.,ition.

Anart from these differences the cycle will be as described for Fig.5 According to the invention: The Dual Torque Opposed Piston Internal Combustion Engine applied as a Diesel.

As with the conventional diesel, the engine will differ from the petrol engine in that instead of the air/petrol mixture being compressed prior to ignition by a spark plug, only the air will be compressed, to such a pressure that the heat generated will ignite a fuel which is injected into the combustion chamber. Due to the fact that in the invention the connression chamber is formed on the secondary side before transfer agness to the primary side it gives a number of options.

The fuel could be injected into the pre-compressed air via a swirl chamber at the primary side only.

Aweak mixture could be injected into the compressed air on the secondary qide,and on transfer to primary side, combustion could be achieved by ignition from an injection of rich mixture. This could,in turn, require a spark plug, All other well known principles applied to diesels would remain.

This diesel system can be applied as a Four Stroke, a Two Stroke (crankcase scavanged) and a Two Stroke ( blower pump) and apart from the differences mentioned, the cycles will be as previously described.

General: In each of the engine systems described, engine construction, flywheels, balancing, timing, ignition, va7ving, electrics etc., unless described otherwise, will be by well known mechanical means, using well known mgehfmic and electrica] compononts, and allowing for al] necessary timine adjustments within the cycles. The drive transmission from primary to secondary crankshafts can be by simple gear train or any other well known method. An illustration for this is shown in Fig. 6.

Tt is also probable that the varying pressures created throughout one combustion process, related to the differing angles of the primary and secondary cranks, cou]d requir;? s bias to the start angles of their respective i!7ea] se,nnts. A]th0iia. this would require further research to establish the actual amount, the bias can be accomodated within the concept of the invention. In the petrol engines, the spark plug will be located in a' combustion pocket, to enable adjustments to ignition timing to be accomodated.

Claims

I An internal combustion engine, comprising, in a single cylinder engine, a common cylinder inside which is housed a pair of opposing pistons. Each piston is connected, via a con-rod to separate crank shafts, situated either end of the cylinder. The crankshafts are connected by a drive system so that they rotate in unison.

The opposing pistons and their crankshafts are so related that during the combustion stroke, the detonation force acts on the pistons, with their respective crankshafts, in turn, being positioned at their most advantageous angular segment of rotation, utilising the maximum torque condition of both movements. The maximum torque output, therefore, transfers from primary to secondary within one cycle. The pistons continue to separate to full volume capacity,prior to closing to form the minimum volume condition. This occurs initially on the secondary side ,before transfer across to the primary,at the start condition for commencement of the following cycle.

All other aspects of the engine system will be by well known conventional means.

The engine will have at least one cylinder system, but may be employed in multiples.
2 A Dual Torque Opposed Piston internal combustion engine as claimed in Claim I applied Rs a Four Stroke Petrol engine.
3 A Dual Torque Opposed Piston internal combustion engine as claimed in Claim I applied as a Two Stroke Petrol engine.(Crankcase scavanged)
4 A Dual Torque Opposed Piston internal combustion engine as claimed in Claim I applied as a Two Stroke Petrol engine. (Blower pump)
5 A Dual Torque Opposed Piston internal combustion engine as claimed in Claim I applied as a Four Stroke Diesel engine.
6 A Dual Torque Opposed Piston internal combustion engine as claimed in Claim I applied as a Two Stroke Diesel engine.(Crankcase scavanged) 7 A Dual Torque Opposed Piston internal combustion engine as claimed in Claim I applied as a Two Stroke Diesel engine.(Blower pump) 8 A Dual Torque Opposed Piston internal combustion engine substantially as described herein with reference to Firures I - of the accompanying drawings.