GB2437088A

GB2437088A - Geared drive system for a diesel engine

Info

Publication number: GB2437088A
Application number: GB0605076A
Authority: GB
Inventors: John Daborn
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-03-14
Filing date: 2006-03-14
Publication date: 2007-10-17
Also published as: GB0605076D0

Abstract

A diesel engine requires a long stroke relative to the cylinder bore size. All diesel engines have the piston stroke slightly greater than the bore diameter. The stroke given by a crankshaft cannot be very much longer than the cylinder bore size. The reason for this is that if a piston stroke was twice the bore size, then the inertia loads would be so great that the engine speed would have to be much slower than a standard engine, and the power output would be much lower than a standard engine. The drive system for a diesel engine allows a piston stroke of up to twice the cylinder bore size, with inertia loads lower than those of a standard diesel crankshaft. The drive system of the invention comprises, for each piston 8, a gear set 1 with two fixed internal gears 2 inside which runs a rotating gear 3, each internal gear 2 having twice as many teeth as the rotating gear 3. Each rotating gear 3 is located by a bearing 5 on a robust drive arm 4 an each connecting rod 7 is connected to extensions of the gears 3 by bearings centred on the pitch circle radius of gear 3. Each gear set 1 has an output shaft 6 connected to adjacent gear set output shaft(s).

Description

Drive system for a diesel internal combustion engine Sheet 1 Described

below is a pre history of engines and engine patents.

A patent for an engine is normally complex, and requires many main features to make such an engine successful.

A simple devise may need only two features to make it successful.

The normal crankshaft has been used for engines for a very long time. The standard crankshaft has a top dead centre and a bottom dead centre. At top dead centre the primary forces and secondary forces combine to give a very high force at high engine speeds.

At mid stroke the connecting rod is at the maximum angle to the vertical, this causes a large side thrust and friction on each piston due to the high diesel engine pressures.

Fuel prices will continue to rise and more efficient engines are required to give improved fuel economy.

Diesel engines give improved fuel economy and give acceptable performance. The aim of the engine drive concept is to provide an improved diesel engine.

Diesel fuel has a low cost to produce compared with petrol, yet costs more than highly refined petrol. The oil companies charge more for diesel fuel for profit motives only.

On the power stroke the exhaust valves open before bottom dead centre, full combustion is not always complete before the exhaust valves open on a normal engine If the standard crankshaft was made to give twice the normal stroke, a diesel engine would be able to have the required compression with ease. No heaters would be required for a cold start. Combusted gas could be used at a lower pressure to produce power, and efficiency would increase. However the inertia increase this would cause would only allow a low engine speed, and the normal crankshaft has poor torque conditions after mid stroke. The crankshaft giving each piston twice the normal stroke would produce less power than an engine with a normal crankshaft, and would have a lower efficiency.

The concept drive has a piston stroke longer than that of a normal engine. The inertia loads are lower than an engine with a normal piston stroke crankshaft.

The drive improves the efficiency of diesel and petrol engines.

The concept drive can replace an in line crankshaft, and an apposed piston crankshaft.

The four in line piston engine is described. Any normal engine format is possible Described below are some of the drive main features.

* There is a straight line drive to each piston.

* The engine drive has lower inertia loads than for a normal engine.

* There is a longer piston stroke than that of a normal engine.

* The normal crankshaft is replaced by a gear drive system.

* The engine can easily reach the high compression of diesel engines.

* Piston side loads are eliminated.

* There is a high torque output * The drive is mainly for diesel engines, but can be used for petrol engines.

Sheet 2 A brief description of the diesel engine concept drive now follows.

The concept uses a series of gear drives to replace the normal crankshaft. The engine that is described in this example is a compact four cylinders in line engine. This is the most common type of engine produced all over the world.

The concept has a gear housing containing four gear drive sets. The mechanism consists of moving gears running inside internal fixed gears. The four gear sets drive the pistons in the same way, as for a normal four in line engine. The pistons have a straight line drive. The pistons can have a stroke longer than is normal, with no increase in inertia.

A more detailed description now follows, with the help of the following drawings.

Fig 1 Shows one side of the gear drive at TDC, mid stroke and BDC.

Fig 2 Shows a gear set 1 driving a piston.

Fig 3 Shows a four in line drive system with two pistons at TDC and two at BDC.

Figs 1 and 2 and 3 are diagrammatic and are not to scale. The terms TDC and BDC depict top dead centre and bottom dead centre, on drawings and descriptions.

The four in line piston engine in this example has the two end cylinders at TDC when the two centre pistons are at BDC, as is standard with this type of engine.

One gear set is described only all other drives are the same. See Fig 1, 2 and 3.

The gear set 1 has two fixed internal gears 2. Running inside each fixed gear is a rotating gear 3. Gear set 1 drives one piston 8 of a four piston in line engine. Four gear sets 1 drive the four pistons 8. The two rotating gears 3 have a suitable number of teeth. Each fixed internal gear has double the number of gear teeth that are on each gear 3.

Each rotating gear 3 is located in a bearing housing 5 on a robust drive arm 4. Each arm support shaft runs on bearings at the centre of each fixed gear 2. Each drive arm has a bearing housing for gear 3. Gears 3 have extensions with connecting rod 7 bearing shaft and bearings on the pitch circle radius of gear 3.

Each gear set I has an output shaft 6 that connects to each adjacent gear set output shaft.

Suitable balance masses are used to give the engine balance.

The concept drive can have a piston stroke that is much longer than that of a normal engine. Diesel engines require the low heat loss of a large swept volume, and a small combustion chamber area.

The concept drive long piston stroke is ideal for diesel engines.

The rotating gears inside the fixed gears give a straight line drive to the pistons.

The engine drive has a torque output higher than a standard crankshaft at least 10 mm closer to TDC, and has a higher torque at mid stroke and near BDC also.

The pistons can have a lower mass due to reduced inertia loads, and no side thrust.

Sheet 3 The pressure in each cylinder on the power stroke drives the piston and connecting rod that drives the gears 3 round. When in this example the engine runs in an anti clockwise direction, the gears 3 are driven in a clockwise direction. The connecting rods have support bearings on a radius that is the same as the pitch circle of the gears 3.

SeeFigsl, 2and3.

Engine drive details The drive sets I having the gears 3 running inside them gives a straight line drive to each of the four pistons 8. Each piston has a straight line drive. Gears 3 are mounted on robust drive bars 4 by ball or roller bearings that have very low friction. The torque due to each piston at the straight line drive is transmitted to the pitch circle of each fixed gear, the driving of gears 3 against the gear teeth of each fixed gear ring, has a reaction force at the pitch circle radius of each fixed gear, driving the engine in the direction of travel, and gives a high torque output for the engine.

The gears 3 rotate at twice the engine speed, and complete a full revolution for 1800 rotation of the engine.

At BDC each gear 3 has completed one revolution and has travelled from the top to the bottom of each fixed gear, this gives the piston twice the stroke of a normal crank throw.

The arrangement gives good torque about gears 3 near TDC and BDC, and the force at the pitch circle radius of each fixed gear as a reaction to the drive against it, gives a high torque output for the engine.

The fact that gears 3 rotate at twice the speed of the engine, as TDC and BDC are reached the inertia of gears 3 will carry the engine through these points and will add a small torque to the engine at these points via the gear teeth.

The reaction driving force at the fixed gear pitch radius and the long stroke the concept gives with no increase of inertia forces, make the concept ideal for diesel engines.

The extended stroke is mainly to give ease of high compression, and allows power to be obtained from lower pressure combusted gases than is normal.

A description of pistons travelling down from TDC

As each piston descends from TDC, and drives each gear 3 about its bearings, if the drive arm 4 in this example rotates anti clockwise ten gear teeth past TDC on each fixed gear 2, then each gear 3 will rotate ten teeth in a clockwise direction, and will return each connecting rod big end back to the centre line of each fixed gear set 1. This action will repeat at all positions and gives a straight line drive to the pistons eliminating side thrust.

The turning back of each connecting rod to the centre of each fixed gear, slows the piston descent, and reduces piston acceleration forces. The action repeats on the return stroke.

The concept drive at 180 after TDC on each fixed gear, the gears 3 have completed revolution one, have completed the down stroke, giving a long period of high torque radius about gears 3, and about each fixed gear 2 pitch radius by reaction forces that drives the engine. The concept drive inertia forces are lower than for a normal engine.

Sheet 4 As each piston travels towards the concept BDC gears 3 move into a good torque position near to BDC. The gas pressure at the extended engine strokes will produce power and will improve fuel economy. The exhaust system will have less emissions and noise.

The long stroke of the concept engine allows more time to ensure ulill combustion always takes place before the exhaust valves open.

Induction stroke The induction stroke will have more time to induce air into the cylinder due to the extended piston stroke.

Compression stroke The compression stroke for diesel engines having the long stroke, and smaller bore, should be able to cold start without using a cylinder heating system.

The long stroke gives a high swept volume and a small area combustion chamber area.

The inertia forces due to the concept gear drive are very low for such a long piston stroke length. The concept inertia forces are less than that for an engine having the same cylinder capacity and a nonnal diesel engine stroke.

A petrol engine could have a near spherical combustion chamber.

Engine types that can use the concept drive Apposed piston engines with any number of cylinders that are in line to give low production costs and good balance, (not drawn).

V2 to V24 cylinder engines can be made (not drawn).

In line engines from 2 to 24 cylinders can be made. Only a four in line engine is drawn, as this is the most common engine produced all over the world.

All the engines use the same kind of gear sets as used for the four in line engine.

Diesel or petrol engines can use the concept drive system.

A specific embodiment of the concept will now be described by way of example See Figs 1, 2 and 3, and sheets 1, 2, 3 and 4.

The concept is a drive system that can be used as a replacement for crankshaft engines.

The drive gives a longer piston stroke than normal engines, with lower inertia forces, and the piston drive is straight line giving no piston side thrust.

The concept drive is ideal for diesel engines as the large swept volume to the small combustion chamber area loses less heat. The long stroke allows easy high compression.

The drive gives the engine a higher torque output than a normal crankshaft, and allows power to be obtained from low gas pressures. Full combustion will always be achieved.

The engine exhaust system will be simple and will have lower emissions than is normal.

Claims

CLAiMS Sheet A drive system for a diesel internal combustion engine,

comprising a drive that is described for one gear set, to give a straight line drive to a piston, the gear set has two fixed internal gears that are spaced a suitable distance apart, in a one piece housing, two drive arms have their bearings at the centre of the two fixed gears, the drive arms have bearings that rotating gears shafts run in, running inside each of the fixed gears is a rotating gear, the two rotating gears have extensions that support a joining crank pin that has its centre on the pitch circle radius of the gears, the fixed gears have twice the number of gear teeth that each of the two rotating gears have, to drive a four in line engine as given as an example, requires four gear sets, the rotating gears give an engine a very high torque, their drive is from the fixed gear teeth, the drive arms supporting the gears are in bearings at the centre of the fixed gears, the torque is almost double that of a normal engine crank throw, the piston stroke is equal to the diameter of the fixed gears, this is twice the crank throw of the rotating gears, this is ideal for a diesel engine that requires a high compression and a small combustion chamber, the long piston stroke is achieved with no increase in inertia, the long stroke enables full combustion in each cylinder to take place, before the exhaust valves open.

2 The drive system for a diesel internal combustion engine according to claim 1, can be used for any kind of internal combustion engine.

3 An engine drive substantially as hereinbefore described, with reference to and as illustrated in the accompanying drawings