GB2188981A

GB2188981A - Balanced rotary cylinder reciprocating piston i.c. engine

Info

Publication number: GB2188981A
Application number: GB08608968A
Authority: GB
Inventors: Brian Gale Macdonald
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-04-12
Filing date: 1986-04-12
Publication date: 1987-10-14
Also published as: GB8608968D0

Abstract

A two stroke engine has a rotary cylinder member (12) and a piston assembly (13) acting within the cylinder. The cylinder (12) rotates on a fixed mounting (11) about an axis (15) which is both the centre of rotation and the centre of balance of the engine. The piston assembly (13) includes a connecting rod (18) having its big end (19) mounted on an offset crank pin (17) so that it is pivoted about an axis (26) which is both the axis of pivoting movement and the axis of balance of the piston assembly. Similarly the piston (22) is mounted to a gudgeon pin (21) in such a way that the rocking movement of the piston in use is about an axis coinciding with its own axis of balance. Because the entire engine and each sub-assembly is arranged to rotate or rock about its own axis of balance, the amount of vibration to be expected is very low and the engine can be run at relatively high speed with an excellent power to weight ratio. Two cylinder and three cylinder versions of the engine are also described (Figs. 8 to 11). <IMAGE>

Description

SPECIFICATION Internal combustion engine This invention relates to an internal combustion engine of the rotary cylinder type.

Rotary cylinder internal combustion engines have the theoretical advantage that they can produce a rotary power output directly with the use of a stationary crank shaft. The oscillating motion of the connecting rods is substantially reduced in this type of engine.

However, previously proposed rotary cylinder internal combustion engines have suffered from vibration problems due to small but unavoidable unbalanced oscillating forces.

It is an object of the present invention to provide a rotary cylinder internal combustion engine which overcomes or reduces this disadvantage.

According to the invention there is provided a rotary cylinder internal combustion engine comprising; a fixed mounting; a cylinder member rotatably mounted on said fixed mounting; a piston assembly also rotatably mounted on said fixed mounting within the cylinder member and cooperating with a cylinder of the cylinder member; the axes of rotation of the cylinder member and piston assembly respectively coinciding with their axes of balance and said axes of rotation being spaced and parallel.

The fixed mounting may include an off-set crank pin on which the piston assembly is rotatably mounted about an axis of rotation spaced from and parallel to the axis of rotation of the cylinder member on said fixed mounting.

The piston assembly preferably comprises a piston pivotally mounted on a connecting rod which is in turn rotationally mounted at said axis of rotation of the piston assembly on the fixed mounting.

The axis of pivotal mounting of the piston on the connecting rod preferably coincides with the axis of balance of the piston.

The invention will now be described in more detail by way of example only with reference to the accompanying drawings in which; Figure 1 is an axial section of a two stroke engine embodying the invention.

Figure 2 to Figure 7 are diagrammatical sequence drawings of the rotary cylinder of Fig.

1 in plan section.

Figure 8 is an axial section of a three cylinder two stroke engine embodying the invention.

Figure 9 is a plan sectional view of the engine of Fig. 8.

Figure 10 is an axial section of a two cylinder two stroke engine embodying the invention.

Figure 11 is a plan sectional view of the engine of Fig. 10.

Referring firstly to Fig. 1 of the drawings, a rotary cylinder internal combustion engine generally indicated at 10 comprises a fixed mount 11, a rotary cylinder member 12 and a piston assembly 13 which is mounted within the cylinder.

The cylinder member 12 is mounted on main ball race bearings 14 to the fixed mounting 11 and is rotatable about an axis 15. The fixed mounting 11 has a stub 16 projecting within the cylinder member 12 and providing an offset crank pin 17 for the piston assembly 13.

The piston assembly 13 comprises a connecting rod 18 having its big end 19 mounted on the offset crank pin 17 and being connected at its little end 20 by a gudgeon pin 21 to opposite sides of the hollow domed piston proper 22. The piston is provided with piston rings 23 of generally known type and is capable of reciprocation within a cylinder bore 24 of the cylinder member 12. The connecting rod 18 has a projecting bob weight 25 extending from the big end in a direction away from the piston proper 22.

The axis or rotation of the piston 22 coincides with its axis or balance at the centre line of the gudgeon pin 21.

The piston assembly 13 comprising the connecting rod 18, the gudgeon pin 21, rings 23 and piston proper 22 is balanced by the bob weight 25 so that its axis of balance or rotary centre of gravity is coincident with the axis of rotation 26 defined by the offset crank pin 17 on the stub 16.

Similarly, the axis of rotation 15 of the cylinder member coincides with the axis of balance or rotary centre of gravity of the cylinder member including its various external components to be described.

In use, the cylinder member 12 rotates about the axis 15, in a balanced fashion and the piston assembly 13 rotates about the axis 26 in a balanced fashion so that no oscillating forces are produced by the rotation of the engine.

Incorporating these principles, various types of engine can be produced. By way of example, the two stroke engine illustrated has a single cylinder provided with a spark plug 27 having a high tension lead 28 which rotates with the cylinder member 12 and which has a brush type contact 29 with a distributor 30 so as to produce a timed spark at the spark plug 27.

Injection means 31, also rotating with the cylinder member, are provided to inject petrol and lubricating oil mixture into the cylinder for ignition by the spark plug 27. The fuel injector 31 is fed through a fuel injection pipe 32 from a rotating fuel supply element 33 which is provided with a rotating petrol and oil seal at its connection, on the axis 15, with the fixed mounting.

Exhaust gases from the cylinder member 12 are discharged through an exhaust passageway 34 which is concentric with the rotating fuel supply elements 33 and which communicates with an exhaust pipe 35 in the fixed housing. A rotating gas seal 36 prevents leakage of exhaust gases and the connection between the exhaust outlet 34 and the exhaust pipe 35 passes through a spider 37 supporting the rotating fuel supply element 33.

Fig. 2 diagrammatically illustrates an air intake scoop 38 which is designed to achieve ram compression. This is provided with a reed valve 39 to prevent back flow whilst crank case compression takes place during piston descent. Air induction ports 40 are provided alongside the piston assembly and these act as transfer ports to provide air induction to the cylinder for combustion of the fuel.

Considering the sequence of drawings Figs.

2 to 7, which illustrate the operation of the engine diagrammatically, it will be seen that the axes 26 and 15 remain fixed in both relative and absolute position throughout the engine cycle. However, both the cylinder member 12 and the piston assembly inside it rotate around their respective axes of rotatation 15 and 26 during the cycle.

On starting the engine, the rotating cylinder member 12 moves to the position shown in Fig. 3 and draws the piston assembly 13 down the cylinder 24 as shown in Fig. 3.

Combustion of fuel in air takes place under the action of the spark plug 27 and the continued rotation of the cylinder to the exhaust position shown in Fig. 5 then uncovers the exhaust ports 34. The exhaust ports 34 are at right angles to the air induction transfer ports 40 and the action of the illustrated engine is of the Schnuerl type in which the entering air intake is angled so as to scavenge the remaining exhaust gases from the cylinder.

It will be appreciated that the rotating cylinder member effectively acts as its own flywheel, since the centre of balance of the cylinder member coincides with its axis of rotation 15 so that it does not exert any oscillating forces on the fixed mounting member.

Similarly, although the piston 22 moves in the cylinder bore 24, the whole piston assembly 13 rotates about the axis 26 which coincides with its centre of balance so as to exert no nett oscillating force on the stub 16 of the fixed mounting 11. The piston proper 22 rocks slightly with respect to the connecting rod 18 about the axis of the gudgeon pin 21 but this provides only a small perturbation in the rotation of the piston assembly 13.

Because the moving mengine components can theoretically be balanced to normal balancing tolerances the amount of vibration to be expected is very low. This means that the engine can be run at a relatively high speed so that the power-to-weight ratio of the engine is much better than would normally be expected with a standard two stroke engine.

The same principles can be applied to other forms of engine than the two-stroke and to pumps, compressors and similar machines.

The engine described may have particular application in for example model aircraft or in the powering of other apparatus where it is important to ensure minimum vibration but where, for example, a gas turbine engine would be too expensive.

Figs. 8 and 9 of the drawings illustrate a three cylinder version of the engine. The three cylinders 40, 41 and 42 are angled at 1200 axes relative to the centre line of a fixed mount 43 on which they are rotatably mounted by bearings diagrammatically illustrated at 44. A fixed stub or crank pin 45 is provided with its axis 46 spaced from the centre line 47 of the fixed mounting 43. The two have spaced and parallel axes as before.

However, three connecting rods 48, 49, 50 are all pivotally mounted on the crank pin 45.

The apparatus functions as described above in relation to the single cylinder version with the exception that, because the three cylinders are at different phases of their power cycle at any given time, crank case compression may not be created by the movement of the individual pistons. Unless high speed rotation provides ram compression, this means that a separate compressor must be used to feed compressed air to the system. This is done through a central passageway 51 in the fixed mounting 43.

It will be noted, that in order to fix the connecting rods to the common crank pin 45, they must be offset axially along the crank pin. In the example illustrated, the connecting rod 48 is journalled between the connecting rods 49 and 50. Correspondingly, the cylinders are positioned at different levels to accommodate the pistons which will not be described in further detail.

The crank case again rotates and drive is taken from the external gear 52.

Referring to Figs. 10 and 11 of the drawings, a two cylinder two stroke engine is iliustrated. This is basically the same as the first described embodiment illustrated in Figs. 1 to 7 with the exception that the cylinder 60 is additionally provided, in line with the cylinder 24. The piston proper, 22, is extended to provide a second piston 61 moving in the cylinder 60. These pistons move in unison and are articulated on a common gudgeon pin 21.

As the crank case rotates, the two pistons operate in anti-phase.

With both of the last described embodiments the rotating parts will again be balanced so that their axes of rotation correspond with their axes of balance.

However, in the case of the last embodiment described with reference to Figs. 10 and 11, it is possible to use the engine as a stationary engine by keeping the crank case sta tionary and allowing the central mounting 62 and crank pin 63 to rotate. The pistons will recipriocate in the cylinder bores 24, 60.

Claims

1. A rotary cylinder internal combustion engine comprising; a fixed mounting; a cylinder member rotatably mounted on said fixed mounting; a piston assembly also rotably mounted on said fixed mounting within the cylinder member and cooperating with a cylinder of the cylinder member; the axes of rotation of the cylinder member and piston assembly respectively coinciding with their axes of balance and said axes of rotation being spaced and parallel.

2. An engine according to Claim 1 wherein the fixed mounting includes an offset crank pin on which the piston assembly is rotatably mounted about an axis of rotation spaced from and parallel to the axis of rotation of the cylinder member on said fixed mounting.

3. An engine according to Claim 2 wherein the piston assembly comprises a piston pivotally mounted on a connecting rod which is in turn rotationally mounted at said axis of rotation of the piston assemly on the fixed mounting.

4. An engine according to Claim 3 wherein the axis of pivotal mounting of the piston on the connecting rod coincides with the axis of balance of the piston.

5. A rotary cylinder internal combustion engine substantially as hereinbefore described with reference to and as illustrated in Figs. 1 to 7 of the accompanying drawings.

6. A rotary cylinder internal combustion engine substantially as hereinbefore described with reference to and as illustrated in Figs. 8 and 9 of the accompanying drawings.

7. A rotary cylinder internal combustion engine substantially as hereinbefore described with reference to and as illustrated in Figs. 10 and 11 of the accompanying drawings.