GB2487550A

GB2487550A - Internal combustion engine with valved lower cylinder ports

Info

Publication number: GB2487550A
Application number: GB1101315.8A
Authority: GB
Inventors: Peter Einar James; Thomas Peter James
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-01-26
Filing date: 2011-01-26
Publication date: 2012-08-01
Also published as: GB201101315D0

Abstract

Exhaust and/or inlet ports (b and f) are positioned at or near the bottom of the piston stroke of an internal combustion engine in addition to the conventional exhaust and inlet valves in the cylinder head which remain. The additional lower ports improve the flow of gases in and out of the cylinder. The movement of the piston is used to uncover the ports and partly determines the timing of the port opening. During the 4-stroke cycle the port will be exposed twice so in order to prevent unwanted flow a valve (a) is positioned in the port to prevent the exhaust port flowing during the intake stroke and/or the intake port flowing during the exhaust stroke. The lower cylinder ports may also move up and down, independently of the valves, to alter and further control the timing of the effective opening and closing of the lower ports.

Description

Improvements in. or relating to Internal Combustion Engines By the use of Lower Cylinder Ports We, Peter Einar James and Thomas Peter James of 3, Station Terrace, Minehead, Som.TA24 5BD do hereby declare the nature of this invention and in what manner the same is to be performed and arranged to be particularly described and ascertained in

and by the following statement:

1. Our invention relates to internal combustion engines such as used in automobiles, motor cycles and applications using reciprocating pistons in the 4 stroke (and may also be applied to the 6 stroke cycle) Otto cycle and has for its object to improve the induction of air (or air fuel mixture) and the better exhausting of the products of combustion together with reducing detonation, knock and pre-ignition by lowering the inlet charge temperature and promoting a more turbulent charge.

2. In order that our invention may be properly understood we will describe the existing practice and how our invention achieves its objectives. We will also describe the same with the aid of drawings: Conventional practice is to use a valve period longer than the theoretically ideall 80 deg of an inlet or exhaust stroke (typically in excess of 250 deg) this being required due to the acceleration constraints of the cam and valve system and the need to ensure that a useful amount of valve lift is available during the stroke.

A typical exhaust valve will open 50-60 deg before the piston has reached the bottom of the power stroke. Because of the articulation of the connecting rod and the big end, little mechanical advantage and hence work is to be gained by leaving the valve closed (in fact this sudden early release of exhaust may be beneficial in helping scavenging in tuned length exhaust manifolds) The early opening of the exhaust valve ensures that full valve lift is available during the exhaust stroke. The exhaust valve is also kept open after the piston has reached the top of the exhaust stroke and does not close until typically 20 deg into the induction stroke, this not only helps extend the valve period but also helps scavenge residual exhaust gases by the incoming new charge.

Returning to the bottom of the power stroke our invention would introduce an exhaust port (retaining the existing poppet valves in the cylinder head) which would be uncovered by the piston (in a similar manner to the piston in a two-stroke engine) at say 50-60 deg before BDC This port would then be closed off again when the piston was on its way up on the exhaust stroke( a period of over 1 Oodeg could be achieved).

This would allow a substantial amount of hot exhaust gas to be removed, reducing the pressure on the piston and hence the work done (pumping loss) by the piston in ejecting the exhaust gases on the exhaust stroke. As a consequence much of the heat nonnally transmitted to the exhaust valve would be removed through the new port, this will significantly reduce the combustion chamber (and especially exhaust valve) temperature thereby reducing pre-ignition and combustion knock allowing a raised compression ratio to be used.

It will be noted that this new lower cylinder exhaust port would interfere with the induction stroke, the piston would open the port whilst drawing in a fresh charge (via the original inlet valve). Our invention would introduce a rotary valve( run at 1/4 engine speed) sliding or sleeve valve to close the port off during the intake stroke. The opening of the port is controlled by the piston, the rotary valve is not subjected to combustion pressures and is only used to close off the port during the intake stroke. It is the position of the piston which opens and closes the port the rotary or sliding valve will not influence or change the port timing. The lower cylinder port may be arranged to move up and down (independently of the valve) thus altering its effective period and therefore its timing. The conventional exhaust valve would be retained and may be reduced in size and its period altered to reflect is reduced function.

The lower cylinder valve may be of various designs e.g. rotary,sliding plate,sleeve or any gas tight closing and many be operated by mechanical, hydraulic or electro-mechanical systems.

The quick opening achieved by the new additional exhaust port would produce a pressure wave which may be usefully employed in promoting scavenging or improving turbocharging systems either in conjunction with or separate to the existing exhaust system. Indeed one lower cylinder port may be arranged to scavenge an adjacent cylinder via its conventional valve or vice-versa and coud also be applied to the inlet system. There would also be the possibility of recovering some useful work e.g. via a turbine to charge a battery Turning to the intake stroke a similar lower cylinder port and valve arrangement could be employed to improve the induction process. The lower cylinder intake port would also be exposed by the piston when nearing the bottom of the intake stroke thereby improving the volumetric efficiency and reducing pumping losses. The position of the lower cylinder port could be arranged to move up or down the cylinder to alter its timing so as to improve economy and fuel efficiency. The conventional inlet valve would be retained, but its dimensions and its period and timing might be altered to reflect its new function.

With the use of lower cylinder ports the cylinder would be charged and exhaused by two separate valve systems one using conventional valves in the combustion chamber and a piston operated port in the cylinder. There would be no need to use this system on both exhaust and intake, either could be used independently without employing the other.

3. Benefits of using lower cylinder ports would be: the improved volumetric efficiency of an engine and hence its performance, a reduction of pumping losses, the ability to use a higher compression ratio and a reduced need for long valve periods and overlap. -The above is to be read in conjunction with accomparting drawings: Fig 1. Shows rotary valve a open to exhaust port b with piston c about to uncover the port.

(the rotary valve may be operated by gears, eccentric, hydraulic, electro-mechanical, pneumatic or a combination of these systems) Fig 2 Shows the exhaust port b uncovered by the piston c at the bottom of the power stroke and flow of exhaust gases through the rotary valve a The position of the port b (and portf in Fig 4.) could be arranged to move up or down (e.g. by use of moving sleeve) to alter timing (an inlet port would flow in the opposite direction) Fig 3. Shows the rotary valve a closed to the exhaust port b at the bottom of the intake stroke (whilst the port is uncovered no flow is possible due to the closed valve) Fig 4. shows an arrangement using both exhaust port Ii and intake portf shown at the bottom of the power stroke FigS. shows an alternative slide valve e operated by an eccentric, cam,hydraulic, gear, electro-mechanical, pnumatic or a combination of these systems (which may combine both inlet & exhaust ports) Fig 6. shows a alternative sleeve valvef operated by an eccentic, cam, hydraulic, gear or electro-mechanical, pnumatic or a combination of these systems (which may combine both inlet & exhaust ports) Fig 7. shows an alternative piston type plunger valve operated by an ecentric, this may also be used on the inlet side and may also be arranged to perform the functions of the existing valves in the cylinderhead by extending the plunger piston to form a compound sleeve valve. Thereby creating an engine with sleeve valves operating at both ends of the cylinder.

Claims

Claims The filling & scavenging of the cylinder( volumetric efficiency) will be improved and as a result an increase in output will be seen. It would be posible to reduce the duration of the (cam driven) valve period so that a reduction of emissions can be realised. The exhausting of hot gases away from the cylinder head would allow a higher compression ratio to be used by reducing combustion charge temperatures and exhaust gas contamination. The quick opening of the lower cylinder exhaust port would allow some usful energy to be recoverd from the still expanding gases. asdetailed in the full description.AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWSClaims Improvements in or relating to Internal Combustion EngJnes By the use of Lower Cylinder Ports The improvements to the induction and exhaust cycles of a 4 stroke internal combustion engine 1. Allow more power to be produced as a result of improved volumetric efficiency and a reduction of pumping losses.
2. Allow exhaust energy to be used more easily e.g. driving a turbine or generator
3. Have a benificial effect on harmful! emmisions as less conventional valve period may be used and valve overlap reduced.
4. Reduce the temperature in the combustion chamber allowing a higher comression ratio to be * used there by increasing power and reducing unwanted enimisions. Alternatively fuels of a lower octane ratio may be used *: : :
5. Allow the more exhaust pulse to be used to scavenge adjacent cylinders. * e.S