GB2349417A

GB2349417A - I.c. engine with piston connected by two con-rods to a pair of contra-rotating crankshafts

Info

Publication number: GB2349417A
Application number: GB9909371A
Authority: GB
Inventors: Brian Mawdsley
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-04-26
Filing date: 1999-04-26
Publication date: 2000-11-01
Also published as: GB9909371D0

Abstract

A single or multi-cylinder internal combustion engine in which a piston or pistons reciprocate in a cylinder or cylinders. Each piston is connected to two connecting rods 2 and 3 which are in turn connected to the offset crank bearings 8 and 9 of a pair of parallel crank shafts. The crank shafts are connected together by gears 10 and 11 or some other means such that they contra-rotate at the same speed with their offset crank bearings moving in tandem such that the piston 1 can reciprocate in its cylinder while being supported in a constant relationship to the cylinder axis by the two connecting rods. The contra-rotation and relative positioning of the offset bearings of the two crank shafts create a balanced mechanism in the plane of the two crank shafts. The maintenance of the piston position relative to the cylinder by the two connecting rods allows short stroke lengths to be employed to increase engine speed and power output. Opposed twin cylinder configurations are also described (figs. 4, 5).

Description

IMPROVEMENT TO INTERNA COMBUSTION ENGINE.

This invention relates to an improved internal combustion engine.

Internal combustion engines have many different configurations, each with their own particular advantages. Single cylinder engines are mechanically simple, light, compact and cheap to produce. Multi-cylinder engines are better balanced and have shorter strokes. This allows them to rotate faster and produce more power.

The power output of existing single cylinder engines is limited by their poor balance and high piston speeds. There currently exists no configuration that t combines the advantages of a single cylinder engine or an engine with a small number of large capacity cylinders with those of a multi-cylinder engine with a larger number of smaller capacity cylinders.

According to the present invention there is provided a single or multi-cylinder engine in which a piston or pistons reciprocate in a cylinder or cylinders. Each piston is connected by pivoting means to two connecting rods, the axes of these two pivoting means being positioned parallel to each other and some distance apart. The opposite ends of the two connecting rods are connected to the offset crank bearings of a pair of parallel crank shafts. The crank shafts are connected by gears or some other means so that they contra-rotate at the same speed with their offset crank bearings moving in tandem such that the piston or pistons can reciprocate in the cylinder or cylinders while being continuously supported in a fixed relationship to the cylinder axis in all directions perpendicular to the cylinder axis by the two connecting rods. The contra-rotation and relative positioning of the offset bearings of the two crank shafts creates a balanced mechanism in a direction perpendicular to the cylinder axis. The combination of the piston and crank shafts counter-weights produces balance in the direction of the cylinder axis in the normal way.

As the piston is supported in a fixed relationship to the cylinder bore by the action of the two connecting rods it is not free to rock in the bore unlike a normal piston mounted on a single connecting rod. This eliminates any constraining relationship between bore and stroke length allowing the bore to be larger and the stroke to be shorter than similar existing engines. The provision of both good balance and short stroke length allows the engine to revolve at much higher speeds and thus produce more power. The crank shafts may be connected to one piston to create a single cylinder engine or to two pistons to create an opposed twin engine. Multiples of these two configurations could be used to create multi-cylinder engines.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which ;- Fig 1 shows a side elevation of a single cylinder engine Fig 2 shows a perspective view of the twin crank shafts, gears and connecting rods with all other parts removed.

Fig 3 shows another perspective view with the piston in place.

Fig 4 shows an opposed twin cylinder configuration in which the two crank shafts are connected to two pistons by way of two pairs of connecting rods.

Fig 5 shows an opposed twin cylinder configuration in which the two pairs of connecting rods are attached to two different pairs of offset bearings 180 degrees apart.

With reference to the drawings a piston 1 is connected via two bearings or bushes 6 & 7, commonly known as'little ends', to two connecting rods 2 & 3. The opposite ends of the connecting rods are connected to the offset crank bearings 8 & 9, commonly known as'big ends', of two parallel crank shafts 4 & 5. The crank shafts are connected by gears 10 & 11 so that they contra-rotate at the same speed.

The offset bearings 8 & 9 are positioned relative to each other such that the piston is held perpendicular to the cylinder bore 14 throughout its cycle by the two connecting rods. As the crank shafts rotate the connecting rods 2 & 3, the offset crank bearings 8 & 9 and the counter weights 12 & 13 continuously move in opposing directions in the plain perpendicular to the cylinder axis creating dynamic balance. The piston 1 does not require a skirt because it is maintained in its correct position by the two connecting rods.

The other components necessary for the working of a combustion engine are not shown and are not the subject of this patent.

The bore/stroke ratio, which in existing engines is restricted to approximately 1.5: 1 can be freely chosen to optimise engine performance. For example a ratio of 2.5: 1 will produce a total piston area/stroke ratio approximately equivalent to a six cylinder engine with a bore/stroke ratio of 1: 1.

There is an added advantage to the configuration shown in Figure 5. The opposing movement of the two pistons reduces the need for crank shaft counter weights whilst retaining perfect balance.

It is envisaged that the cylinder head design needed to create good combustion over such a large piston area would be laid out as a number of smaller 'sub'combustion areas.

Claims

Claims; 1-a single cylinder internal combustion engine in which the piston is connected by pivoting means to two connecting rods, the axes of these two pivoting means being positioned under the piston parallel to each other and some distance apart. The opposite ends of the connecting rods are connected to the offset crank bearings of a pair of parallel crank shafts. The crank shafts are connected together by gears or some other means such that they contra-rotate at the same speed with their offset crank bearings positioned to move in tandem so that the piston is free to reciprocate in the cylinder whilst being continuously supported in a fixed relationship to the cylinder axis in all directions perpendicular to that axis by the two connecting rods.

2-a single cylinder internal combustion engine as in claim 1 in which a second piston and cylinder are added and where the second piston is mounted on two additional connecting rods in a similar manner to the first on the opposite side of the crank shafts. These connecting rods are connected to the same offset bearings of the same two crank shafts as the first pair of connecting rods.

3-an internal combustion engine as in claims 1 and 2 in which the connecting rods of the second piston are connected to additional offset bearings on the same two crank shafts positioned at 180 degrees or any other convenient angle to the first offset bearings supporting the first piston.

4-an internal combustion engine as in claims 1,2 and 3 in which a multi-cylinder engine is created from any multiple or combination of the configurations described in claims 1,2 and 3.

5-an internal combustion engine as in claims 1,2,3 and 4 in which each piston is supported by an additional second pair of connecting rods, the second pair being placed alongside the first and identically duplicating the motion of the first pair.