GB2385375A - I.c. engine with balanced crankshaft and opposed integrally-linked pistons - Google Patents

Abstract

By using the horizontally opposed piston arrangement but with exact cylinder alignment and in combination with an external balanced crankshaft 2, both piston crowns 1 can be linked to create a linked piston 3, which shares a single conrod 4 and gudgeon pin 10, utilising a two arm 16 connection, where the bottom and top arm 16 might pass beneath and above the crankshaft's main journals 11 respectively, and where the saxon window 25 in each arm 16 allows the uninhibited rotation of the conrod 4 and associated crankshaft connector web 31 and crankpin 43.

Description

Siamese Piston This invention relates to reciprocating opposed pistons.

It is particularly applicable to any internal combustion engine or pump. Then invention utilises reciprocating opposed (boxer) pistons, well known in engine manufacture.

A specific embodiment of the invention will now be described by way example with the accompanying drawing in which: Figure 1-6 show in side view the effects of side forces between a contemporary piston 1 and cylinder 5.

Figure 7 shows in perspective a siamese opposed piston 3 featuring four connecting legs 6,7,8,9.

Figure 8 shows in perspective a siamese opposed piston 3 featuring external balancer cut outs 14.

Figure 9 shows in perspective a siamese opposed piston 3 featuring internal balancer cut outs 15.

Figure 10 shows a vertical and axial externally balanced siamese piston 20 centre section in-situ in the engine.

Figure 11 shows a vertical and axial internally balanced siamese piston 21 centre section in-situ in the engine.

Figure 12 shows an horizontal and axial externally balanced siamese piston 20 centre section in-situ in the engine.

Figure 13 shows an horizontal and axial internally balanced siamese piston 21 centre section in-situ in the engine.

Figure 14 shows split view vertical section normal to the axis, through the gudgeon pin 10 and crankshaft 2 of an externally balanced siamese piston 20 centre section in-situ in the engine.

Figure 15 shows split view vertical section normal to the axis, through the gudgeon pin 10 and crankshaft 2 of an internally balanced siamese piston 21 centre section in-sit'' in the engine.

Figure 16 shows splittable 3 bearing crankshaft 25 with counter balance webs omitted for visual clarity.

Figure 17 shows conventional 3 bearing internally balanced crankshaft 26 with standard positioned counter balancer webs 17 but reduced diameter (necked) shaft 30 either side of the balance webs 17.

Figure 18 shows 3 bearing externally balanced crankshaft 27 with outboard (externally) positioned counter balance webs 18 and reduced diameter (necked) shaft 30 either side of the connector web 31.

Figure 19 shows 3 bearing double balanced crankshaft 28 with standard positioned counter balance webs 17, reduced diameter (necked) shaft 30, and additional outboard counter balance webs 18.

Figure 20 shows an externally balanced siamese piston 20 in isometric perspective, featuring an upper stiffening bridge 32.

Figure 21 shows an externally balanced siamese piston 20 in exploded isometric perspective, featuring an upper stiffening bridge 32 and 3 bolts.

Figure 22 shows an internally balanced siamese piston 21 in isometric perspective featuring an upper stiffening bridge 33.

Figure 23 shows an internally balanced siamese piston 21 in isometric perspective, featuring two Remountable upper legs 34.

Figure 24 shows an internally balanced siamese piston in isometric perspective featuring male 35 and female 36 pistons and centre coupling.

Figure 25 shows a siamese piston 3 in isometric perspective, featuring a bolted leg 24 junction, also shown is a lock ring 37 proposal and an option of an attachable stiffening bridge 38.

Figure 26 shows a siamese piston 3 in isometric perspective, featuring a curved tube union, 39 also shown is a locking collet 40 proposal.

Figure 27 shows a siamese piston 3 in isometric perspective, featuring a bolted straight rod union 41, with a clip over stiffening section 42.

Figure 28 shows a balanced flat 8 siamese boxer layout.

Figure 29 shows a "X" siamese boxer layout.

Figure 30 shows a "Cross siamese boxer layout.

Figure 31 shows a two legged siamese piston.

Figure 32 shows vertical section normal to the axis crankshaft 2 of a side balanced siamese piston 52 centre section in-situ in the engine.

In figure 1-6 it is shown that due to the nature of reciprocation, side forces are exerted on the walls of the cylinder 5 by the piston 1, at various stages of in the cycle of operation, conventionally these side forces are counteracted by piston skirts 12.

The axial distance between the top of the piston 1 and lowermost point on the opposing skirt effectively produces the true height of what we shall call the angular control height.

This angular control height is relatively short in comparison to the combined height of cylinder 5 and connecting rod 4, this means the piston 1 will achieve a relatively high level of angular position for a given force, whereby accompanying; cylinder 5 wall gouging, high friction and looser tolerance between piston 1 and cylinder 5, must be considered for every stroke.

In an opposed cylinder engine, exactly the same situation exists for the opposing piston 1 found operating 180 degrees but offset to one side around the crankshaft 2.

By using the horizontally opposed arrangement but with exact cylinder alignment, both pistons 1 can be linked to create a Siamese piston 3 illustrated in figure 7, which shares a single Conrad 4 and gudgeon pin 10, utilising a four leg connection, where the bottom two legs 8 and 9, and top two legs 6 and 7, might pass beneath and above the crankshaft's main ioumals 11 respectively, and where also the left hand legs 6 and 8, and right hand legs 7and 9, might pass the left hand and right hand side respectively of the path generated by the uninhibited rotation of the Conrad 4 and associated crankshaft connector web 31 and crankpin 43.

This Siamese piston 3 will be stabilised axially by opposing ends of the piston, vastly increasing angular control height, proportionally reducing cylinder 5 to piston 1 friction.

in addition, by linking the opposed pistons 1, manufacture is facilitated, particularly in consideration of machining accuracy and tolerances.

With the basic invention described we can consider the specific parameters and choices for crankshaft 2, Conrad 4, type of counter balance web(s) 17 and type of siamese piston 3, in order for the siamese piston invention to be optimised.

The siamese piston 3 shown in figure 7 is a single component, producing excellent tolerance and manufacture possibilities, but thereby requiring a splittable crankshaft 25, i.e. dissemble at each crank pin 7, as shown by example in figure 16. This type of splittable crankshaft 25, although in existence, is not favoured by manufacturers, and therefore, splitting the siamese piston 3 in order to assemble the crankshaft 2 is deemed preferable.

The siamese piston 3 can either be split into two connecting pistons (figures 24-27), or can remain as a unitary siamese piston body 13 connected by the lower legs 8,9 (figures 20-23), with the two upper legs 6,7 attaching after crankshaft 2 assembly. The unitary siamese piston body 13 is likely to be favoured for manufacture.

The conrod 4 designed for conventional piston engines will require a clean sheet designed to be optimised for this application, although the standard design will also function with the siamese piston 3 as seen in section in figure 10. An alternative conrod 44, better able to cope with the new tensile forces is seen in figure 11.

The counter balance webs 17 and position are critical to the design of the main bearings 23, width of the engine, and especially siamese piston 3 itself. In figure 16 we see a crankshaft 25 denuded of balance webs 17 to illustrate the primary function of the crankshaft 25, however, this type of crankshaft 25 is unfavoured due to inherent engine vibration.

The conventional crankshaft 26 is shown in figure 17, whereby the balance webs 17 are a continuation of the connector webs 31 for the crank pin 43 This is hereon termed internally balancing. Internal balancing requires extensive cut outs 15 between the upper and lower leg pairings respectively, thereby weakening the siamese piston 3.

An alternative crankshaft 27 is shown where the balance webs 18 are moved outboard on the main journals 11, adjacent to the bearing 23, hereon known as externally balancing. The external balance web 18 is totally separate from and additional too the connector web 31. This allows the siamese piston 3 to have a much smaller clearance

balance web 18 externally would appear to create a width penalty on the engine arrangement, by thickening the tip of the web 18, the web 18 can circumnavigate the bearing shell 92 on its outer edge, whilst also passing through grooves provided on the extemally balanced siamese piston 14. These grooves 14 are cut in an area that does not significantly reduce the strength of the externally balanced siamese piston 20. This maintains a relatively compact engine width best illustrated in figure 12.

A fourth double balanced crankshaft 28 alternative is shown in figure 19, whereby both intema! 17 and external balance webs 18 are employed. Due to the nature of the siamese piston 3 concept? despite overall reciprocating weight being reduced, the reciprocating weight per Conrad 4 is increased, thereby requiring increased counter balancing, doubling the balancing provision comfortably provides the necessary extra counter balancing.

Figures 1 1,13 and 15 show orthographic sectional elevations of a four cylinder internally balanced siamese piston 21 engine assembly.

Figures 10,12 and 14 show orthographic sectional elevations of a four cylinder externally balanced siamese piston 20engine assembly.

Figures 20 and 21 show a practical assembly solution for an externally balanced siamese piston 20, whereby a uniter,' combination u pper leg bridge 32 attaches to the main siamese piston body 13 with screws. Of further interest is the assembly sequence of the engine which follows; siamese piston bodies 13, bearing shells 22, crankshaft 27 then upper leg bridge 32, this allows the upper leg bridge 32 to have a thickness wel! beyond that of the cylindrical piston profile, because the gap within the crankcase, betA'en the cylinders 5, is longer than that of the stroke of the piston 20, hereon known as the oversize section zone 45, so it is possible to increase the sectional size of the upper leg bridge 32 as shown. This greatly improves rigidity and integrity of the upper leg bridge 32, and the union to the main siamese piston body 13.

Figures 22 and 23 show havoc alternative solutions for upper leg bridges 33,34 to be used on an internally balanced siamese piston 21. Figure 22 shows an integrated leg pair 33 including a raised roof zone link, which assembles vertica!!y but avoids contact

to Conrad 4 sweep, whilst also providing increased integrity and rigidity to the component. Figure 23 shows separate upper legs 34 that assemble from the side and screw separately down to the siamese piston body 13. These legs also feature large section thickening in the oversize section zone 45.

Figure 24 shows a unique male 35 and female siamese piston 36 union, whereby the male piston 35 assembles into the sump zone, over the crankshaft 27 then rotates and slides into its cylinder. The female piston 36 is assembled conventionally through the cylinder block 46, so that all four leas 24 on the female piston 36 then slide over around the crankshaft 27 and home into recesses on the male piston 35. The considerable leg overlap provides a high level of integration. Two bolts then pass through holes in the left hand and right hand leg pairs respectively. Small nicks on the female piston legs 24 engage against these bolts to prevent removal.

Figures 25-27 all show more conventional siamese piston 3 construction concepts where four similar to one another legs 24 complete the siamese union, the advantage of all these concepts, is that they are assembled and dissembled following crankshaft 2 assembly (except the curved rod 39 solution). This prevents disturbing the crankshaft 2 and bearing shells 22 for piston maintenance and also potentially provides narrower spacing between main bearings 23, because space is not required to deliver the siamese piston body 13 through the sump zone. However it is shown in figures 12,13,14,15 that by using bearing shells 22 that are assembled after the siamese piston body 13 is delivered through the block, the width between main bearings 23 can be minimised.

In figure 25 the non-gudgeoned piston 47 end has four integral legs 24, which once passed over the crankshaft 2 locate on to matching recesses on the gudgeoned piston 48, where they can be screwed. In addition a proposal by way of example, shows an alternative fastener wire 49 used to fix the leas 24 instead of bolts.

Also shown is a stiffener section 50, to be bonded to the siamese legs 24, positioned in the oversize section zone 45, to reinforce the leas 24.

In figure 26 both siamese piston ends 47 and 48 resemble conventional pistons 1, whereupon four independent curved rod leas 39 or tubes are affixed to the pistons 47

and 48. The lower rod legs and upper rod legs are located into the pistons before and after crankshaft assembly respectively.

Whereupon they are fixed by means of screws, a collet 40, a lock ring, an expanding circlip or adhesive.

In figure 27 both siamese piston ends 47, 48 are conventional in appearance and the union is made by means of straight rods 41, permanently affixed to one of the piston ends' and held fast at the other by means of screws, lock rings or adhesive. The curved rod 39 and straight rod 41 solutions have the advantage that tubular and higher strength material can be employed in this critical area to reduce weight and increase strength. The straight rod 41 solution has the advantage of simpler engine assembly, while the curved rod 39 solution may use a larger diameter tube or other section.

Further siamese piston 3 construction solutions can be achieved by mixing and matching solutions, for example a siamese piston 3 with two straight rod 41 lower legs 8, 9, with an upper leg bridge 32 would be a practical compromise between strength, lightweight and ease of assembly.

In figures 28-30 we can see alternative engine arrangements for the siamese piston 3 opposed cylinder engine.

In figure 28 we can see an alternative engine block 51 for a flat 8 arrangement to that shown in figures 10-15. While this block 51 is not very compact by comparison, and would require extravagant valve componentry if contemporary valves were employed, it retains a better level of engine balance.

In figures 29 and 30 we can see an "X" and "cross arrangement of cylinders respectively. In figures 31 and 32 we see a two-legged siamese piston proposal. Although four legs would appear to provide the highest stability, 3, 2 or 1 leg(s) can also be used effectively to link both ends of the siamese piston, when a sympathetic; crankshaft, Conrad and counter balance web(s) are employed. The two-legged proposal seen has much larger section legs permissible due to the offset position of the Conrad, the single offset balance web. In addition the distance between main bearings is reduced and should a unitary siamese piston be employed, the crankshaft would only have to split into three parts on a four cylinder engine. In the diagram the siamese piston is shown with a removable upper leg.

Claims (5)

Claims.

1) External balanced type crankshaft and linked piston combination, whereby external balancing refers to repositioning of the crankshaft counterweights on completely separate webs to the crank webs, whereby the position of the counterweight web or webs is outboard relative to the piston axis of one or both of the crank webs, so that the crank pin crankshaft portion denuded of counterweight drives one end of a linked piston via a connecting rod, whereby the linked piston requires only a modest sized upper and lower cut-out to avoid contact to the driving crank pin portion, where the crank pin portion is comprising; crank pin, crank webs and connecting rod and where both ends of the linked piston are connected by four links, with two of each said links sliding above, and two links sliding below, the said external balanced crankshaft, and where the links all reciprocate inboard relative to the external positioned counterweight web or webs, but also reciprocate outboard of the crank pin portion.

2) External balanced type crankshaft and linked piston combination as described in claim 1 featuring inside undercut faces on the counterweight web or webs, which under rotation avoid contacting the linked piston by passing through corresponding and approximately matched width recesses, provided at both ends of the linked piston beneath the piston ring lands, so that the main counterweight thickness pass beside or below the gudgeon pin and through said provided width recesses, thus enabling a larger volume of counter weight, in a narrow overall block width.

3) External balanced type crankshaft as described in claim 1 featuring an outside undercut face on one or more of the counterweights, where the swollen portion of the counterweight circumnavigates behind the full width main bearing, and where the main bearing features an undercut support ring, approximately matching in negative section to that of the outside face of the counterweight, thus enabling a larger volume of counter weight, in a narrow overall block width while still maintaining full width main bearings.

4) External balanced type crankshaft as described in claim 1 featuring swollen tip counterweights, where the outside and inside face undercut features of claims 2 and 4 are combined on the counterweight web or webs, engine block and linked piston, enabling the largest volume of counter weight possible In a narrow overall block width.

Claims continued. O\ 5) External balanced type crankshaft as described in claim 1 featuring a necked smaller diameter zone on the crankshaft portion located between the crank web and the counterweight web, this necked zone being of considerably smaller diameter to that of the main bearing diameter to allow the maximum size possible for the four links of the linked piston which pass around the crankshaft at this point.

6) External balanced type crankshaft as described in claims 2 - featuring a necked smaller diameter zone on the crankshaft portion located between the crank web and the counterweight web, this necked zone being of considerably smaller diameter to that of the main bearing diameter to allow the maximum size possible for the four links of the linked piston which pass around the crankshaft at this point 7) A external balanced type crankshaft and linked piston combination as described herein with references to figures 1-11 of the accompanying drawing.

....CLME: her Amendments to the claims have been filed as follows Claims.! 1) External balanced type crankshaft and linked piston combination, whereby external balancing refers to repositioning of the crankshaft counterweights on completely separate webs to the crank webs, whereby the position of the counterweight web or webs is outboard relative to the piston axis of one or both of the crank webs, so that the crank pin crankshaft portion denuded of counterweighting, drives one end of a double ended linked piston via a connecting rod, whereby the linked piston requires only a modest sized upper and lower cutout to avoid contact to the driving crank pin portion, where the crank pin portion is comprising; crank pin, crank webs and connecting rod and where both ends of the linked piston are connected by four links, with two of each said links sliding above, and two links sliding below, the said external balanced crankshaft, and where the links all reciprocate nearer to the piston axis than the external positioned counterweight web or webs, but also reciprocate further outboard from the piston axis than the crank pin portion.

2) External balanced type crankshaft and linked piston combination as described in claim 1 featuring swollen upper portion(s) on the inside faces on the counterweight web or webs, whereupon rotation, these swollen counterweight portions avoid contacting the linked piston by passing through corresponding and sympathetically matched width recesses, provided at both ends of the linked piston beneath the piston ring lands, so that the main counterweight inside face thickness passes beside or below the gudgeon pin and through said provided width recess or recesses on the linked piston, thus enabling a larger volume of counter weight, in a narrow overall block width, while still permitting full width linked piston links which reciprocate in the area just outside the sweep of the swollen upper portions on the inside face of the counterweight or counterweights.

3) External balanced type crankshaft as described in claim 1 featuring an outside undercut face on one or more of the counterweights, whereby the swollen portion of the counterweight's outer face circumnavigates behind the full width of the main bearing, and where the main bearing features an undercut support ring, approximately matching in negative section to that of the outside face of the counterweight, thus enabling a larger volume of counter weight, in a narrow overall block width while still maintaining full width main bearings.

: . I. t r;.

claims continued. Ill 4) External balanced type crankshaft as described in claim 1 featuring swollen tip counterweights, where the outside and inside face features of claims 2 and 4 are combined on the counterweight web or webs, engine block and linked piston, enabling a large volume of counter weight possible in a narrow overall block width.

5) External balanced type crankshaft as described in claims 1, 2, 3 or 4, featuring a necked smaller diameter zone on the crankshaft portion located between the crank web and the counterweight web, this necked zone being of considerably smaller diameter to that of the main bearing diameter to allow the maximum size possible for the four links of the linked piston which pass around the crankshaft at this point 6) A external balanced type crankshaft and linked piston combination as described herein with references to figures 1-11 of the accompanying drawing.

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