WO1994029574A1

WO1994029574A1 - Piston machine with differential or variable stroke

Info

Publication number: WO1994029574A1
Application number: PCT/NZ1994/000056
Authority: WO
Inventors: John Brengle Taylor
Original assignee: John Brengle Taylor
Priority date: 1993-06-03
Filing date: 1994-06-03
Publication date: 1994-12-22
Also published as: AU6900394A

Abstract

An engine, pump or compressor with a 'Z'-shaped crankshaft (2) providing either two or four strokes of differential length for every revolution of the crankshaft (2). The crankshaft (2) is connected to a piston (1, 1') via a spigot assembly (40) mounted on each crank journal (28, 29), which has at its piston end a spigot (36, 37) on which a stirrup crank (30, 31) is mounted, the stirrup crank (30, 31) being mounted on bearings at right angles to the main bearing journals, the spigot (36, 37) or the stirrup crank (30, 31) supporting a connecting rod (5, 5') for each piston (1, 1').

Description

PISTONMACHINEWITHDIFFERENTIALORVARIABLESTROKE

The invention relates to engines, pumps and compressors and in particular to an engine, pump or compressor with either a differential or variable piston stroke.

At present a wide range of engines and pumps have been produced and a number of these have proposed configurations of linkages and mechanism which result in different lengths of power stroke to exhaust or inlet stroke. This differential stroke length has certain advantages over the fixed stroke lengths of standard internal combustion engines. For example it provides a more efficient internal combustion engine by allowing high pressure gasses to further reduce their pressure in the form of effective mechanical effort before the exhaust valve opens.

An object of the invention is therefore to provide an engine, pump or compressor with either a differential or variable piston stroke.

An object of the invention is to provide an engine, pump or compressor in which four strokes occur in each revolution of its crankshaft.

Further objects and advantages of the invention will become apparent from the following description which is given by way of example only.

According to a first aspect of the invention there is provided an internal combustion engine, pump or compressor in which a crankshaft is shaped so that a cranking journal bearing centre-line thereof is not parallel to the centre-line of main supporting bearing journals of the crankshaft but is at an angle to them, the crankshaft being connected to a piston or reciprocating mass to cause the piston or reciprocating mass, during, one revolution of the crankshaft, to stroke through four movements comprising two stroking movements generally away from the crankshaft and two stroking movements generally towards the crankshaft.

The sequence of the stroking movements are an inlet stroke, a compression stroke, an ignition stroke and an exhaust stroke.

The crankshaft is connected to the piston by way of a spigot assembly mounted on the cranking journal of the crankshaft and has at its piston end a spigot on which a stirrup crank is mounted, the stirrup crank acting to stabilise the reciprocating movement of the spigot assembly by being mounted on bearings mounted at or near to right angles to the main bearing journals and in generally the same plane thereas, the spigot and/or stirrup crank supporting a connecting rod for each piston.

The centre-line of the stirrup crank main journals pass through the centre of action of the cranking journal. The centre-line of the spigot assembly is generally at right angles to the cranking journal.

According to a second aspect of the invention the internal combustion engine, pump or compressor additionally includes the piston or reciprocating mass being adapted to move through four stroking movements that are not all the same dimension or length in that some of the four stroking movements are greater or smaller than the others.

According to a third aspect of the invention there is provided an internal combustion engine, pump or compressor defined in the first aspect and in which the reciprocating arcuate movement of the stirrup crank is confined to one side of the centre-line of the stirrup crank main bearings in a manner that causes the reciprocating pistons to stroke twice in one revolution of the crankshaft.

Further aspects of the invention which should be considered in all its novel aspects will become apparent from the following descriptions which are given by way of example only.

Examples of the invention will now be described with reference to the accompanying drawings in which:

Figure 1 is a diagrammatic representation of an example of the invention with one piston at the end of its power stroke and the other piston at the top of its compression stroke, both strokes being of equal length;

Figure 2 shows a similar diagrammatic representation to that shown in Figure 1 with the relative positions of the crankshaft shown after a rotation of 180° in the crankshaft, the strokes being of variable length;

Figure 3 shows a diagrammatic representation of an alternative example in which the centre-line of the piston (not shown) is offset from the centre-line of the cranking journal to achieve strokes of varying length;

Figure 4 is a perspective view of the internal parts of another example of the invention in the form of an engine;

Figure 5 is a perspective view of a crankshaft for the engine according to the invention and as shown in Figure 4.

Figure 6 is a perspective view of a spigot assembly and its associated bob-weight for the engine shown in Figures 4 and 5;

Figure 7(a) and 7(b) are a perspective view and plan view respectively of a stirrup crank for the engine shown in Figures 4 to 6;

Figure 8 is a forked connecting rod for the engine shown in Figures 4 to 7;

Figure 9 shows a perspective view of the internal moving parts of an alternative construction of engine; and

Figure 10 shows a plan view of a crankshaft and pistons for a side by side cylinder engine according to the invention;

Figure 11 shows an isometric view of an engine block part of which is omitted to show with clarity the parts of a two cylinder engine according to the invention;

Figure 12 shows a side view of an alternative construction of two cylinder engines in which the pistons are in a side by side position;

Figure 13 is an end view in the direction of arrows XIII - XIII as indicated in Figure 12 and in which the crankshaft of the motor has rotated through 90 degrees; Figure 14 is an end view of yet another construction of engine in which the two pistons thereof are mounted in horizontally opposed configuration;

Figure 15 is a side view of an internal combustion engine according to a third aspect of the invention; and

Figure 16 is a plan view of an internal combustion engine according to the third aspect of the invention in which the crankshaft is parallel to the centre-line of the pistons of the engine.

The examples of the invention will be described with reference to its use as an internal combustion engine. It is however, to be appreciated that with modifications the technology can be used as a pump or compressor.

In the examples the same nomenclature has been used where possible to indicate similar parts of the example engines shown.

In Figures 1 and 2 is shown a diagrammatic representation of a piston 1 mounted relative to crankshaft 2. The crankshaft 2 has a cranking journal 3 the centre-line of which is at an angle relative to the centre-line of main supporting bearing journals. The connection between a gudgeon pin 4 mounted in the piston 1 and the cranking journal 3 is by way of a connecting rod 5 and a spigot assembly 6. The connection at 7 between the spigot assembly 6 and the connecting rod 5 allows the spigot assembly 6 to rotate through an arc while the spigot assembly 6 is reciprocating in the direction of arrows 8. In Figure 1 the two positions of the piston 1 are shown and the position dotted shows the position of the piston when it is at top dead centre immediately prior to ignition.

In Figure 2 is a diagrammatic representation similar to that shown in Figure 1. Similar parts of the engine are shown with reference to the same numerals. In this position the extent of reciprocating movement of the spigot assembly 6 is shown as are the limits of movement of the piston 1. The piston numerals 1 in Figure 2 represent the top of the piston in three positions namely top dead centre and at the bottom of its short and long strokes.

In this example the bold lines "a" and "b" (Figure 2) show the different stroke lengths. Also the crankshaft 2 is shown in its two aspects of rotation which are 180 degree apart.

In Figure 3 is shown a representation where the centre¬ line of the piston (not shown) is offset from the centre-line of the cranking journal 3 in order to achieve strokes of varying length. Again similar parts are referenced by the same numerals.

In the example of engine shown in Figures 4 to 8 similar parts are referenced by the same numerals as those used in Figures 1 to 3. The example is shown with an engine having a single piston 1, although it is envisaged that more than one piston can be adapted and connected to the spigot assembly 6 or to a stirrup crank part of the assembled engine is shown in Figure 4 while the parts are shown in more detail in Figures 5 to 8. In Figure 5 is shown the crankshaft 2. The crankshaft 2 has a cranking journal bearing surface 3 the centre-line 8 of which is at an angle to the centre-line of the main bearing journals 9. The crankshaft 2 is balanced by providing weights 10 in association with or integrally formed with the crankshaft.

In Figure 6 is shown a spigot assembly 6 the lower end of which is formed with a bob-weight 11. The spigot assembly 6 has a bore 12 which is used to mount it relative to the cranking journal bearing surface 3. The upper end of the spigot assembly 6 has a spigot 13.

In Figures 7(a) and 7(b) is shown a stirrup crank 14 which is adapted to stabilise the reciprocating movement of the spigot assembly 6 and its bob-weight 11. The stirrup crank 14 has a bore 15 in which the spigot 13 is engaged. The stirrup crank 14 has a pair of bearing journals 16, the centre-line of which may be at right angles to the centre-line of the main supporting bearing journals 9. In this example the centre¬ lines all meet at a common point. The stirrup crank 14 need not be mounted at 90 degrees to the crankshaft 2. Slightly different orientations can be utilised. The stirrup crank 14 may be unnecessary in a construction of the invention which is designed to act solely as a pump or compressor. Alternatively half a stirrup crank can be used. As an alternative (not shown) to the construction shown in Figure 6, the balancing for the engine can be provided by counter rotating masses interacting with the stirrup crank 14. In Figure 8 is shown a forked connecting rod 5. The forked connecting rod 5 is mounted to a gudgeon pin 4 of the piston 1. The end 18 of the connecting rod 5 is mounted relative to bearing surfaces 19 of the stirrup crank 14.

In Figure 9 is shown an alternative construction of engine. In this construction the piston and cylinder centre¬ line 20 is generally vertical and is offset from the centre of action of the cranking journal 3. The piston 1 in this example is shown at the end of its short intake stroke. The crankshaft 2 in this engine has mounted thereon a spigot assembly 13 journalled to move in association with a stirrup crank 14. The spigot assembly 13 is foreshortened in this example and does not include bob-weights which in this example are provided at

21 on the lower end of the stirrup crank 14. The connection at

22 between the stirrup crank 14 and connecting rod 15 is by way of a gudgeon pin type connection pin at 23. The distance "c" between the top of the stirrup crank 14 and pin at 23 is offset. By adjusting the length of this offset different stroke lengths can be obtained.

In use the motion of the piston 1 and its cylinder (not shown) is in accordance with the movement of the first two examples and different strokes exist for exhaust/power as opposed to inlet/compression. The fuel supply for the internal combustion system and its ignition system can be in accordance with standard engineering practices and the advantages are that the invention operates at a low revolutions per minute while at the same time providing high torque. It is to be appreciated that by adjusting the angles between some of the respective parts a variable length of stroke can be obtained. In most of the examples four strokes occur in each revolution of the crankshaft.

As an alternative to the construction shown in Figures 4 and 9 the piston can be connected to one side of the stirrup crank 14 instead of centrally as shown. This allows a twin cylinder construction on either side of the main crankshaft. This construction is shown diagrammatically in Figure 10 and in more detail in the example shown in Figures 12 and 13.

In the example of engine shown in Figure 11 an engine block 24 and sump 25 are shown diagrammatically in outline. The block 24 incorporates bearings (not shown) which support the crankshaft 2 and cylinders 26, 27 in which pistons 1 and 1' respectively can reciprocate. The cylinder block 24 incorporates in accordance with known engineering techniques oil and water passage for lubrication and cooling of the engine.

The crankshaft 2 has a pair of cranking journals 28, 29 to which the pistons 1 and 1' are mounted via stirrup cranks 30, 31 respectively. The stirrup cranks 30, 31 have a somewhat similar construction to that shown in Figure 9 except that bob- weights 32, 33 are manufactured separately and are bolted in known manner to the generally U-shaped sections 34, 35 of the cranks. The section 34, 35 support spigots 36, 37 respectively which act as bearing journals in bearings (not shown) on opposite sides of the engine block 24. The provision of bearings supporting the stirrup cranks 30, 31 stabilise the reciprocating motion in the direction of the arrows 38, 39 of the cranks.

In this example spigot assemblies 40 are for each of the cranks 30, 31 are stabilised by being mounted in bearings (not shown) in the cranks, 30 , 31 at the ends of spigots 41, 42. The cranks 30, 31 can be formed in two parts joined together at line 43 when the cranks 30, 31 are themselves assembled.

Upper ends of the cranks 30, 31 have supports 44, 45 respectively to which connecting rods 5, 5' for the pistons 1, 1' are mounted.

In this construction the relative positions of pistons 1 and 1' show the position 1 at bottom dead centre, this is at the bottom of a longer power stroke while the piston 1' is shown at the end of its shorter exhaust or inlet stroke.

In the construction of engine shown in Figures 12 and 13 this incorporates, as stated previously with reference to figure 10, a twin cylinder and piston construction in which the pistons 1, 1' are on either side of the crankshaft 2. The crankshaft 2 has a single cranking journal 3 on which a spigot assembly 6 with a pair of opposed spigot 46 is mounted. The spigot assembly 6 is supported on a stirrup crank 14 which has a bob-weight 47. The stirrup crank 14 has journal bearings 48 supported on ether side of an engine block (not shown) . The stirrup crank 14 has mountings 49, 50 between which connecting rods 5, 5' are supported on pins 51, 52 respectively. The reciprocating movement of the stirrup crank 14 is in the direction of arrows 53 and this is under the power of the pistons 1, 1' which move in an arc 54 between the centre lines 55, 56 show the limits of movement.

The position of the piston 1 in Figure 12 is at bottom dead centre, that is the end of a power stroke while pistons 1' is at the end of an inlet stroke. Figure 13 shows the position of the pistons 1, 1' after the crankshaft 2 has rotated through 90 degrees.

In Figure 14 is shown schematically a construction of engine with a pair of horizontally opposed pistons 1, 1'. The pistons have connecting rods 5, 5' supported at their inner ends by pins 57, 57' which are supported by a rectangular in end elevation stirrup crank 14 on opposite sides of which are mounts 58, 58' for the pins 57, 57'. The stirrup crank 14 in this example has opposed bearing journals 59 which are mounted in bearings in the engine block (not shown) .

The centre line of the crankshaft 2 in this example is the same horizontal plane 60 as the centre line of the pistons 1, 1' which reciprocate in the direction of the arrows 61, 62. In this constructions the spigot assembly 6 has spigots 63 mounted in bearings (not shown) in the side members 64 of the stirrup crank 14. The points 65, 66 are the tip and bottom points of the cranked regions of the crankshaft 2.

In use rotation of the crankshaft 2 causes the stirrup crank 14 via the spigot assembly 6 to reciprocate under the power supplied from pistons 1, 1'. In the example the pistons 1, 1' are shown in mid stroke.

In Figure 15 is shown a side view of an internal combustion engine with a single piston 1 on one side of the centre-line 67 of the stirrup crank main bearings (not shown) . In this construction the reciprocating arcuate movement (arrow 68) of the stirrup crank 14 is on one side 69 of the centre¬ line 67. The crankshaft 2 is shown in one position while the stirrup crank 14 is shown dotted in a second position where it has rotated through a minor arc. The respective positions of the piston 1 are also indicated. In this construction rotation of the crankshaft 2 through one revolution causes the piston 1 to stroke twice. That is one movement in each of direction. The strokes in this example are of the same length and the dotted position of the piston 1 is bottom dead-centre. The other piston 1 position is top dead-centre.

In Figure 16 is a somewhat similar construction of internal combustion engine. In this construction the crankshaft 2 is not at right angles to the centre-line 70 of the pistons 1 movements but is rather parallel to the centre¬ line 70 and off-set. Again this construction results in two stroking movements in each direction of the piston in one revolution of the crankshaft.

Other advantages of this invention are: to achieve by extended piston travel to give a greater power stroke; to reduce environmental pollution by continuing the combustion process for a greater duration; to provide a higher torque engine in that the complete four cycles are achieved in one crankshaft revolution; to provide a quieter operating engine; and to provide a cooler running longer life engine. Thus by this invention there is provided an engine, pump or compressor with either a differential or variable piston stroke.

Particular examples of the invention have been described by way of example and it is envisaged that improvements and modifications can take place without departing from the scope and spirit of the appended claims.

Claims

CLAIMS :

1. An internal combustion engine, pump or compressor in which a crankshaft is shaped so that a cranking journal bearing centre-line thereof is not parallel to the centre-line of main supporting bearing journals of the crankshaft but is at an angle to them, the crankshaft being connected to a piston or reciprocating mass to cause the piston or reciprocating mass, during, one revolution of the crankshaft, to stroke through four movements comprising two stroking movements generally away from the crankshaft and two stroking movements generally towards the crankshaft.

2. An internal combustion engine, pump or compressor as claimed in claim 1 wherein the crankshaft is connected to the piston by way of a spigot assembly mounted on the cranking journal of the crankshaft and has at its piston end a spigot on which a stirrup crank is mounted, the stirrup crank acting to stabilise the reciprocating movement of the spigot assembly by being mounted on bearings mounted at or near to right angles to the main bearing journals and in generally the same plane thereas, the spigot and/or stirrup crank supporting a connecting rod for each piston.

3. An internal combustion engine, pump or compressor as claimed in claim 2 wherein the centre-line of the stirrup crank main journals pass through the centre of action of the cranking journal.

4. An internal combustion engine, pump or compressor as claimed in claim 3 wherein the centre-line of the spigot assembly is generally at right angles to the cranking journal.

5. An internal combustion engine, pump or compressor as claimed in any one of the preceding claim which additionally includes the piston or reciprocating mass being adapted to move through four stroking movements that are not all the same dimension or length in that some of the four stroking movements are greater or smaller than the others.

6. An internal combustion engine, pump or compressor as claimed in claim 1 and substantially as hereinbefore described with reference to the accompanying drawings.

7. An internal combustion engine as claimed in claim 1 in which the sequence of the stroking movements are an inlet stroke, a compression stroke, an ignition stroke and an exhaust stroke.

8. An internal combustion engine as claimed in claim 7 wherein the compression and ignition strokes are longer than the inlet and exhaust strokes.

9. An internal combustion engine as claimed in claim 8 wherein more than one piston is mounted via a stirrup crank to spigot assembly to a single crankshaft.

10. An internal combustion engine as claimed in claim 8 wherein more than one piston is mounted to a single stirrup crank which is mounted via a spigot assembly to the crankshaft.

11. An internal combustion engine as claimed in claim 8 and substantially as hereinbefore described with reference to either Figures 4 to 8, Figure 8, Figures 11 and 12, Figure 13 or Figure 14.

12. An international combustion engine, pump or compressor as claimed in claim 1 in which the reciprocating arcuate movement of the stirrup crank is confined to one side of the centre-line of the stirrup crank main bearings in a manner that causes the reciprocating piston to stroke twice in one revolution of the crankshaft.