WO2005085596A1

WO2005085596A1 - Reciprocating mechanism for piston engine

Info

Publication number: WO2005085596A1
Application number: PCT/AU2005/000321
Authority: WO
Inventors: Norman Leslie Matthews
Original assignee: Norman Leslie Matthews
Priority date: 2004-03-08
Filing date: 2005-03-08
Publication date: 2005-09-15

Abstract

An engine including a cylinder block that defines at least one bore (102) in which a piston (104) can reciprocate, an elongate connecting rod (106) and means (108) to convert the reciprocating motion of the piston into rotational motion, wherein this means is rotating about a centre of rotation (116) that is not fixed relative to the cylinder block, but which is instead constrained via means (118) that allow movement of said centre of rotation (116) along a defined path only, so that when the piston (104) reciprocates the pinion gears (110) centre of rotation (116) oscillates along the defined path. In use during an engine cycle then, this minimises the angle subtended between the direction of elongation of the connecting rod (106) and the direction of travel of the piston (104) throughout at least a portion of the cycle.

Description

TITLE

RECIPROCATING MECHANISM FOR PISTON ENGINE

TECHNICAL FIELD

The present invention relates to improvements to engines, and in particular internal combustion engines.

BACKGROUND ART

The crankshaft of a conventional internal combustion engine converts the reciprocating motion of the pistons into a rotational output, and is generally located at the bottom of the engine block (or, aside the engine when the cylinders are horizontally arranged). A crankshaft has a journal or a gudgeon pin that is offset from the crankshaft's centre and axis of rotation. An elongate member called a connecting rod is connected to this journal and pin at one end, and to the piston at its further end.

When a conventional internal combustion engine is in operation, the crankshaft is rotated by the reciprocation of the piston(s) via the connecting rod(s). Conventionally, the centre of rotation of the crankshaft is fixed in one position relative to the engine block, by a bearing and bearing mount that is bolted to the engine block in a precise position where it remains fixed, allowing only rotation of the crankshaft.

Conventional reciprocating piston engines are known to incur high friction and wear from excessive pressure to the sides of the combustion chamber and the piston itself, caused by the connecting rod angle from the piston to the crankshaft. This problem occurs because the journal is offset from the position centrally below the piston for the majority of a cycle.

Various attempts have been made to solve this problem and also the related problem that the same angle of the connecting rod's direction from the piston force application to the rotation of the crankshaft is less in its efficiency to rotate the crankshaft; solutions such as: 1. Replacing the crankshaft with a multi-lobate cam rotor(s).

2. Substituting the crankshaft with a scotch yoke.

3. A rotating cam to the crankshaft journal for the piston's connecting rod connection or to part connecting rods.

These solutions have not been adopted by the auto industry however, possibly because they are unacceptable to the industry due to the fact that they change or replace the crankshaft, and by doing so, move away from a component of engines that is well accepted and performs reliably and otherwise suitably, and that has remained unchanged since the beginning of engine development.

It is an object of the present invention to provide an improved engine that overcomes or at least substantially ameliorates the problems associated with the internal combustion engines of the prior art.

Other objects and advantages of the present invention will become apparent from the following description, taken in connection with the accompanying drawings, wherein, by way of illustration and example, an embodiment of the present invention is disclosed.

DISCLOSURE OF THE INVENTION

According to the invention then there is an engine including a cylinder block that defines at least one bore in which a piston can reciprocate, an elongate connecting rod and means to convert the reciprocating motion of the piston into rotational motion, wherein this means is rotating about a centre of rotation that is not fixed relative to the cylinder block, so that when the engine is in use, the angle subtended between the direction of elongation of the connecting rod and the direction of travel of the piston is minimised throughout at least a portion of a complete cycle of the engine.

Preferably, the means to convert the reciprocating motion of the piston into rotational motion is a pinion gear, and the connection point between the connecting rod and the pinion gear is offset a distance from the centre of rotation of the gear. Preferably, the reciprocating motion of the piston into rotational motion is a crankshaft connected to a pinion gear such that the crankshaft and the pinion gear share a common axis of rotation.

Preferably, the centre of rotation for the pinion gear is constrained via means that allow movement of said centre of rotation along a defined path only, so that when the piston reciprocates the pinion gears centre of rotation oscillates along the defined path.

Preferably, the means for constraining the movement of the centre of rotation is a slot of finite length.

Preferably, the length of the slot is approximately twice the connecting rods offset distance from the centre of rotation of the pinion gear.

Preferably, the slot is arcuate and concentric with a further gear.

Preferably, the midpoint of the slot is aligned with the centre of the piston.

Preferably, the block is stationary and the pinion gear drives the further gear, said further gear driving an output shaft.

Preferably, the movement of the centre of rotation of the pinion gear relative to the cylinder block is to a first end of the slot and then back again as the piston completes one stoke.

Preferably, the one-way and lateral travel of the crankshaft begins when the piston moves down, and ends when the piston is midway down, and that is approximately half of one stroke, the crankshaft then moves back toward the centre of the slot back to its first position, and does so progressively, as the piston completes the stroke, which is completed when the piston reaches the bottom of its stroke again.

Preferably, the engine includes a plurality of cylinders arranged radially around the second gear.

Preferably, the line of action of the piston is directed radially outwards. Preferably, pairs of cylinders are arranged so as to be directly opposing one another.

Preferably, the crankshaft centre of rotation for opposing pairs of cylinders are connected by an arm that pivots about the centre of rotation of the output shaft.

In a further form the radial arc is defined by a pivot arm connected to the centre of rotation of the crankshaft.

Preferably, the pivot arm pivots about the centre of rotation of the output shaft.

Preferably, the pivot arm connects opposing pairs of cylinders.

In a further form the cylinder block rotates relative to a fixed portion of the engine, and the cylinder block is attached to an output shaft.

Preferably, the fixed portion is a casing, the further gear is fixed relative to the casing, and the cylinder block is a rotor retained by the casing such that the rotor is free to rotate about an axis passing through its centre.

Preferably the piston is oriented within the cylinder block such that the magnitude and sense of combustion are directed so as to maximise rotational effect of the cylinder block around its axis of rotation, relative to the fixed portion.

Preferably the gear fixed to the fixed portion is an internal ring gear.

Preferably the piston is oriented in a plane normal to the centre of rotation of the block.

Preferably the piston is oriented with its head pointed in the direction that the cylinder block will rotate.

Preferably the piston is offset form the centre of rotation of the block.

Preferably the engine is an internal combustion engine. Preferably, the radial arc through which the crankshaft travels is substantially the same as the radius of the fixed gear.

In a further form of the invention, the means for constraining movement of the centre of rotation of the pinion gear is an elongate element having first and second ends, where the first end is pivotally attached to a fixed point so that the second end can swing through a finite distance, and the second end retains the centre of rotation of the pinion gear.

In a further form of the invention, the means for constraining movement of the centre of rotation of the pinion gear is a disc that is free to rotate a finite distance around a fixed centre point.

In a further form of the invention, there is an engine including a cylinder block that defines at least one bore in which a piston can reciprocate, an elongate connecting rod and a crankshaft which is not the output shaft for the engine, where the crankshaft is rotating about a centre of rotation that is not fixed relative to the cylinder block.

Preferably, there are pinion gears and constrainment means at both ends of the centre of rotation of the crankshaft and pinion gears.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of this invention it will now be described with respect to the preferred embodiment which shall be described herein with the assistance of drawings wherein;

Figure 1 is an exploded view of an engine according to the present invention showing hidden detail; and

Figure 2 is a sectional view through the block and casing at A-A;

Figure 3 is a sectional view through an engine according to a further form of the invention;

Figures 4a to d are detailed sectional views through the engine in Figure 3; Figure 5 is a sectional view through an engine according to a yet a further form of the invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Now referring to the illustrations, and in particular to Figure 1 , there is a fuel burning internal combustion engine 1 having a fixed portion in the form of a casing 2 and a separate cylinder block 3. The block 3 is a rotor that is retained by the casing 2 such that the block 3 is free to rotate about an axis of rotation 14 passing through its centre.

It is to be understood by a person skilled in the relevant art that an external casing is not a rigid requirement to make this engine work, all that is need is an external structure to which a ring gear can be attached, such as a plate, block or the like.

The block 3 defines combustion chambers 22 for four cylinders 4; each cylinder including pistons 5, connecting rods 6, and crankshafts 7. Gudgeon pins 9 and 10 connect the pistons 5 to crankshafts 7, which in turn have pinion gears 11 attached to them so that the crankshaft and the pinion gears have a common axis of rotation B.

There is an arcuate slot 30 of finite length machined into the block 3. This slot 30 constrains the centre of rotation B for the crankshaft 7 and pinion gear 11 so that this centre of rotation B can move relative to the block 3 along the finite path defined by the slot 30.

This common axis of rotation B then floats within the slot 30 of finite length that is formed into the block 3, so that when the piston reciprocates the crankshaft 7 and pinion gears 11 centre of rotation B oscillates within the slot 30.

In use then, combustion of an air fuel mix in combustion chambers 22 drives the piston 5 and block 3 in opposing directions, this in turn rotates the pinion gear 11 that is connected to the crankshaft 7, the pinion gear 11 also engages a ring type gear 12 fixed to the casing 2, such that the rotation of the pinion gear 11 on the ring type gear 12 contributes to the rotation of the cylinder block 3 relative to the casing 2 thereby providing a work output, whilst simultaneously driving the piston 5 back into a position where it can accept and then compress a fresh charge of air and fuel.

At the moment following ignition in the combustion chamber 22, engine block 3 begins moving rotationally, and the piston 5 moves, down or away from the cylinder head 20.

As the piston 5 moves down, the centre of rotation of the crankshaft and pinion gear travels along the slot 30, which is arcuate and concentric with the ring gear 12. With the block 3 rotating in a clockwise direction, the centre of rotation B of the crankshaft 7 is then retained by the slot so that it moves laterally through a radial arc relative to the cylinder block 3, thereby minimizing the angle subtended between the direction of elongation of the connecting rod 6 and the direction of travel of the piston 5 throughout a complete cycle of the engine.

An advantage of this arrangement is that it extends the time the piston 5 is held at top dead centre (TDC); the crankshaft 7 is moved laterally along the arcuate slot 30, and that arc of travel is a portion of said cylinder circle radius, and by the direction of its travel at that time of the piston stroke being clockwise, when the engine block's rotation is clockwise and the crankshaft's rotation is clockwise. This movement of the crankshaft closer to the piston is unique to this engine configuration as the piston cylinders are offset from centre on a tangent and to one side of the engine's centre.

By delaying the piston at top dead centre after ignition, the amount of work transferred to the cylinder block, and therefore to the rotation of the block is increased.

Now referring to Figure 3, which illustrates an engine having a fixed cylinder block 100, that in this case defines eight bores 102 in which eight pistons 104 can reciprocate. The line of action of each piston 104 is directed radially outwards, and each piston 104 has a connecting rod 106, which connects to a crankshaft 108, and a pinion gear 110 attached to the crankshaft. There is a second gear 112 attached to an output shaft 114 that is free to rotate relative to the block 100, the second gear 112 engages each of the pinion gears 110. It is to be understood by a person skilled in the relevant art that the pistons are not restricted to being directed radially outwards, they may for instance be directed radially inwards, or in fact not radially directed at all, with the second gear engaging on either of the inner or outer sides of the pinion gear.

Each pinion gear and crankshaft is mounted to means that ensure rotation of the gear and crankshaft in one direction only. The pinion gears 110 and crankshafts 108 each share a common centre of rotation. Each crankshaft 108 is located in an elliptically shaped cavity 120 in the block; this cavity is sized and adapted to provide clearance for the crankshaft even as it oscillates.

It is to be understood by a person skilled in the relevant art that for each pinion gear 110 and crankshaft there can be more than one piston.

There is an arcuate slot 118 of finite length machined into the block 100. This slot 118 constrains the centre of rotation 116 for the crankshaft 108 and pinion gear 110 so that this centre of rotation 116 can move relative to the block 3 along the finite path defined by the slot 118.

The crankshaft 108 is rotating about a centre of rotation 116 that can move laterally, along the defined radial arc relative to the cylinder block 100, so as to minimise the angle subtended between the direction of elongation of the connecting rod 106 and the direction of travel of the piston 104 throughout the engine cycle.

The radial arc is defined by a slot 118 that retains the rotational centre of the crankshaft 116; this slot 118 is formed into a portion of the engine that is fixed relative to the block. The centre of the slot 118 is located directly below the centre of the piston 104, and the distance from the centre of the slot to an end of the slot is the same as the offset of the piston 104 on the crankshaft 108.

Some significant advantages of reducing the angle subtended between the direction of elongation of the connecting rod 106 and the direction of travel of the piston 104 throughout the engine cycle is that it reduces friction and wear on the sides of the pistons, improves the angle of the connecting rod relative to the crankshaft throughout the engine cycle, and keeps the piston near Top Dead Centre for longer, thereby ensuring better, more complete combustion. In operation then, when the piston is at Top Dead Centre (TDC), as shown in Figure 4a, the rotational centre of the crankshaft 116 sits at the top centre of the radial slot 118 so that the connecting rod 106 is directly below the centre of the piston 104.

As combustion occurs and the flame grows, the piston is driven down (see Figure 4b), the rotational centre of the crankshaft 116 moves downwardly and outwardly to the right, along the slot 118 as the pinion gear 110 rotates, and the connecting rod in a position directly below the centre of the piston 104, even though the pinion gear has been rotated and drive transmitted via the second gear 112 and output shaft 114.

As the piston reaches Bottom Dead Centre, (BDC) as shown in Figure 4c, the pinion gear has rotated through 180 degrees, but the connecting rod is again in a position directly below the centre of the piston 104.

As the piston is driven upwardly (see Figure 4d) during as per during a compression or exhaust stroke, the rotational centre of the crankshaft 116 moves downwardly and outwardly to the left, along the slot 118 as the pinion gear 110 rotates, returning the connecting rod to a position directly below the centre of the piston 104. Off setting the crankshaft before it begins or as it begins to move up reduces the energy needed to return, although some energy is used some to off set it initially.

A significant advantage of this arrangement is that the line of action of combustion is maintained substantially axially through the connecting rod. This means that smaller, lighter connecting rods, pins and bearings can be utilized, and side wear on pistons will be significantly reduced.

When operating as an internal combustion engine, running for instance on a known four stroke cycle, the combustion of a fresh air fuel mixture causes the cylinders104 to reciprocate, this reciprocation is converted into a rotational motion by the crankshaft 108, which in turn drives the second gear 112 attached to the output shaft 114, via the pinion gear 110 attached to the crankshaft

Referring now to Figure 5, where a further embodiment of the invention is illustrated. Here the radial arc that the crankshafts centre of rotation travels on is defined by a pivot arm 140 that pivots about the centre of rotation of the output shaft 142. Furthermore, the pivot arm 140 connects opposing pairs of cylinders 144 and 146.

It is to be understood by a person skilled in the art that the crankshaft may be moved to one side a greater distance than needed, thereby moving the connecting rod past the vertical, a small discrepancy will not significantly effect performance.

An important additional advantage of engines of the type with a fixed block above is that the diameter of the block can be increased to permit incorporation of extra cylinders, so that an engine with approximate dimensions of 1.2m in diameter by 100mm height can be produced with 18 cylinders. Such sizing allows also for the inclusion of engine ancillaries such as exhaust, alternators and the like.

Such an engine has significant benefits because fuel consumption can be reduced by up to 30%, and thermal efficiency can be increased by improving piston, connecting rod and crankshaft thrust alignment in this manner. This is achieved by using the disclosed invention, and is made possible because the crankshafts are not used to output the work directly, as per a conventional engine, and so can be moved relative to the block.

Although the invention has been herein shown and described in what is conceived to be the most practical and preferred embodiment, it is recognised that departures can be made within the scope of the invention, which is not to be limited to the details described herein but is to be accorded the full scope of the specification as to embrace any and all equivalent devices and apparatus.

Claims

1. An engine including a cylinder block that defines at least one bore in which a piston can reciprocate, an elongate connecting rod and means to convert the reciprocating motion of the piston into rotational motion, wherein this means is rotating about a centre of rotation that is not fixed relative to the cylinder block, so that when the engine is in use, the angle subtended between the direction of elongation of the connecting rod and the direction of travel of the piston is minimised throughout at least a portion of a complete cycle of the engine.

2. The engine as in the immediately preceding claim further characterised in that the means to convert the reciprocating motion of the piston into rotational motion is a pinion gear, and the connection point between the connecting rod and the pinion gear is offset a distance from the centre of rotation of the gear.

3. The engine as in claim 1 further characterised in that the means to convert the reciprocating motion of the piston into rotational motion is a crankshaft connected to a pinion gear such that the crankshaft and the pinion gear share a common axis of rotation.

4. The engine as in any one of the preceding claims further characterised in that the centre of rotation for the pinion gear is constrained via means that allow movement of said centre of rotation along a defined path only, so that when the piston reciprocates the pinion gears centre of rotation oscillates along the defined path.

5. The engine as in any one of the preceding claims further characterised in that the means for constraining the movement of the centre of rotation to the defined path is a slot of finite length.

6. The engine as in any one of the preceding claims further characterised in that the length of the defined path is approximately twice the connecting rods offset distance from the centre of rotation of the pinion gear.

7. The engine as in any one of the preceding claims further characterised in that the slot is arcuate and concentric with a further gear with which the pinion gear is in rotational contact.

8. The engine as in any one of the preceding claims further characterised in that the midpoint of the path is aligned with the centre of the piston.

9. The engine as in any one of the preceding claims further characterised in that the cylinder block is stationary and the pinion gear drives the further gear, said further gear driving an output shaft.

10. The engine as in any one of claims 1 to 8 further characterised in that the cylinder block rotates relative to a fixed portion of the engine, and the cylinder block is attached to an output shaft.

11. The engine as in claim 10 further characterised in that the fixed portion is an engine casing, the further gear is fixed relative to the casing so as to be non rotating, and the cylinder block is a rotor retained by the casing such that the rotor is free to rotate about an axis passing through its centre, and the pinion gear rotates on and around the further fixed gear.

12. An engine including a cylinder block that defines at least one bore in which a piston can reciprocate, an elongate connecting rod and means to convert the reciprocating motion of the piston into rotational motion, wherein this means is rotating about a centre of rotation that is not fixed relative to the cylinder block, but which is instead constrained via means that allow movement of said centre of rotation along a defined path only, so that when the piston reciprocates the pinion gears centre of rotation oscillates along the defined path.

13. The engine as in any one of claims 1 to 4 further characterised in that the means for constraining movement of the centre of rotation of the pinion gear is an elongate element having first and second ends, where the first end is pivotally attached to a fixed point so that the second end can swing through a finite distance, and the second end retains the centre of rotation of the pinion gear.

14. The engine as in as in any one of claims 1 to 4 further characterised in that the means for constraining movement of the centre of rotation of the pinion gear is a disc that is free to rotate in a first direction a finite distance around a fixed centre point and then return.

15. The engine as in either of claims 13 or 14 further characterised in that the finite distance is approximately twice the connecting rods offset distance from the centre of rotation of the pinion gear.

16. The engine as in any one of the preceding claims further characterised in that the defined path is arcuate and concentric with a further gear.

17. The engine as in any one of the preceding claims further characterised in that the midpoint of the finite path is aligned with the centre of the piston.

18. An engine including a cylinder block that defines at least one bore in which a piston can reciprocate, an elongate connecting rod and a crankshaft, which is not the output shaft for the engine, where the crankshaft is rotating about a centre of rotation that is not fixed relative to the cylinder block.

19. The engine as in any one of the preceding claims further characterised in that the engine is an internal combustion engine, steam engine or generator.

20. The engine as in any one of the preceding claims further characterised in that that the engine is a compressor or pump.

21. An engine substantially as described in the specification with reference to and as illustrated by the accompanying illustrations.