GB2173855A

GB2173855A - Variable volume stratified charge engine

Info

Publication number: GB2173855A
Application number: GB08601562A
Authority: GB
Inventors: Stephen Peer
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-03-25
Filing date: 1986-01-23
Publication date: 1986-10-22
Also published as: GB8601562D0; GB8507640D0

Abstract

A gasoline engine which also has a multifuel capability has its combustion initiated by spark in a small cylinder 12 closed at one end by a piston 9 actuated by a camshaft or eccentric to close its volume after ignition and to open on the induction stroke of the main piston 2. This cylinder 12 lies to one side of the main cylinder 7 and communicates with it via a small passage or combustion window 21. Above the cylinder 12 is located the spark plug and a small inlet valve 18 or a fuel injection nozzle 23, Fig. 1A, whilst above the main cylinder 7 are located the inlet and exhaust valves. The shaft driving the piston 9 of the small cylinder 12 is driven at half crankshaft speed. <IMAGE>

Description

SPECIFICATION This invention relates to a variable volume engine with stratified charge The invention contained in this description with associated drawings and graphs shows important improvements to internal combustion engines for use in passenger cars.

The following improvements contain one major feature over other engines in that its function reduces the effects of exhaust emissions without losing power performance.

This is mainly due to its important improvements in the fuel air burn cycle and stratified charge effect for better combustion thus improving exhaust emissions. These improvements consist of the incorporation of an additional cylinder and piston lying to one side and communicating with the main cylinder but of a smaller size and which the piston is driven by the crankshaft.

It has a special relationship to the crankshaft motion or speed in each cycle, the small piston being haft the speed or motion of the main crankshaft drive piston. The main piston takes the normal expansion of gases as with any internal combustion engine but the small additional piston plunger accomplishes a better local charge admission of rich fuel mixture of small quantity which is drawn in through a small inlet valve which has a separate passage of its own ie. separate to the main cylinder inlet port & valve.

This has the advantage of feeding a local rich mixture to the spark plug located directly above the cavity whilst a weaker mixture is drawn in through the larger inlet valve directly above the main piston. On the compression stroke the local rich mixture charge is held and stabilized in the cavity ready for ignition where the spark plug is located. Thus allowing a better ignition to commence more effectively with the weaker mixture held in the main cylinder & the expulsion of the initial flame front from the small cylinder. This is effected by the cavity piston closing on the cavity cylinder volume.

The admission cycle has additional displacement volume caused by the small cylinder extending to a position where on admission stroke this expands and assists the main piston to draw in a greater charge volume than in the conventional case.

It will also sustain more cylinder pressure m.e.p. as time loss will be reduced on the power stroke due to volume conservation.

This can be explained by the volume of combustion reducing faster than pressure drop (ie.

cylinder pressure is not weakened by too fast piston flight out growing pressure development in the cylinder as the cylinder expands on the power stroke.) Through the effects of the plunger piston closing on the exhaust stroke it has a larger displacement volume closing to expulse exhaust gases more rapidly than the conventional case thus permiting the valve timing to close sooner for better admission trapping and also to close later for exhaust timing to provide additional cylinder pressure conservancey on the power stroke for more engine torque.

All this will give better volumetric & thermal performance by the admission of more charge volume through the displacement of the small cylinder cavity piston.

Thus effectively increasing and decreasing the displacement volume by utilising dead volume that normally exists in the conventional engine. Also one important feature is that the cam action of the inlet ports 19 & 16 can be phase angle changed as an additional variable 17 thus allowing tuning for improved combustion.

The two inlet ports 16 & 19 lead to a common inlet manifold but still having separate passages to a dual venturi carburettor whose venturi diameters will be proportionate to the port size and power requirement of the engine.

The smaller venturi can be incorporated in the same body as the main intake venturi but being much smaller in order to deal with the feeding of the small rich mixture previously mentioned entering port 19. Whilst the other venturi, being much larger provides for a much higher proportion of air to fuel mix and will feed a weaker mixture to port 16. The butterfly can be ganged or compounded for opening movement when throttling.

One alternative is to locate a direct injection nozzle located in the small cylinder instead of the miniscale valve and port arrangement so to direct fuel near the spark plug. This has the added advantage of less complicated valve train therebye reducing frictional losses.

EXAMPLE; To illustrate by sketches and graphs we can show case examples of the invention as follows; Figure 1 A section through one cylinder as applied to an internal combustion engine showing PISTON 2, CONROD 3, CAVITY CHAMBER 8 and PISTON 9. The action PIS TON 9 is by eccentric & small conrod Figure la is similar to Fig. 1 but has fuel injection directed into the small cylinder 8.

Figure 2 shows side view section of one cylinder with side view of eccentric cam & BR< conrod to small piston 9.

Figure 2A shows the same view but with alternative cam action 6 with alternative fuel feed to the small cavity chamber 8 ie. miniscale valve & port arrangement.

Figure 3 shows in planview the cylinder 7 showing location of sparkplug & porting arrangement.

Figure 3A shows in planview the same as Fig. 3 but with fuel injection as an alternative.

Figure 4 represents in graphic form an air cycle showing an improved cycle against the coventional case. TIME SAVING; WORKDONE; and ADDITIONAL DISPLACEMENT.

Figure 5 represents the motion of the cavity piston 9 with motion of the main crankshaft & BR< piston Figure 6 shows a section through the piston 9 but with detail of the cam action 6.

Claims

CLAIMS A variable volume gasolene engine comprising of various ways of assisting flame travel by the action of a cavity piston arrangement. The arrangement incorporates a small piston cylinder to one side of the main cylinder and leading to it. The small cylinder is closed by a small piston whos action pulses the flame travel and induces small charge volumes.

CLAIM 1 Stratified charge internal combustion engine which has a variable volume capability in the induction combustion & exhaust cycles.
CLAIM 2 A stratified charge engine having a variable volume feature as CLAIM 1 but where it is possible to draw in a separate charge or inject a separate charge mixture by the action of the small piston localised near the spark plug.
CLAIM 3 A stratified internal combustion engine having as in CLAIM 1 & 2 wherein a rich fuel mixture of small quantity can be held in the cavity cylinder whilst a weak majority air fuel mixture is drawn in by the normal process of the main piston receding and inlet valve opening.
CLAIM 4 A stratified internal combustion engine that has the possibility of using alternative fuels like ALCOHOL, KEROSENE or METH ANE GAS having a multi-fuel purpose.
CLAIM 5 A stratified charge engine as in CLAIM 3 where after ignition to the local rich mixture held near the spark the flame front is pushed into the main stream of cylinder turbulence by the cavity piston action which closes this local volume. This assists flame growth and ensures that the weak mixture is burnt in the main cylinder by a torch effect.
CLAIM 6 A statified charge engine as claimed in any proceding claim wherebye after complete combustion burn on exhaust stroke the plunger piston in the cavity closes the volume in the cavity to assist exhaust gas expulsion thus allowing late exhaust valve opening event with subsequent gas torque saving.
CLAIM 7 A stratified charge engine as in CLAIM 6 that by reducing the volume as in CLAIM 6 such that exhaust gas residuals are expulsed more efficiently and effectively than the conventional case therebye improving combustion and reducing polutants.
CLAIM 8 A stratified charge engine as claimed in any proceding claim wherebye that feature of varying the cavity volume will produce additional displacement volume charge on the induction stoke thus improving volumetric efficiency.

CLAIMS Amendments to the claims have been filed, and have the following effect: New or textually amended claims have been filed as follows:-
9. A stratified charge variable volume improving the Flame Volume to Combustion Volume Ratio by reducing unburnt Flame mixture volume after ignition by the effect of volume reduction caused by the plunger piston. Reduction of unburnt flame volume to crankshaft angle reduces the effects of flame extinction or quench therefore reducing Hydrocarbon residuals in the exhaust.