Internal combustion engine

Abstract

An internal combustion engine has a crankshaft having at least one associated cylinder chamber for rotating the crankshaft. Each cylinder chamber is configured with at least two crank big end journals associated with the cylinder chamber. There are at least two variable-length conrods, each conrod being independently connected to one of the corresponding crank big end journals. Each conrod is operable to extend into and retract from the cylinder chamber during operation, such that, as the conrods extend and retract throughout a piston cycle, a first of the conrods lags behind a second of the conrods. During the compression stage of a piston cycle of a given cylinder chamber, the second conrod reaches full extension while the first lagging conrod remains partially extended, and as the first conrod reaches full extension, the second conrod contracts, thereby increasing the dwell time of the piston at or near top dead centre.

Description

[0001] Internal Combustion Engine

[0002] This disclosure relates to a system to improve efficiency and power of a combustion engine by increasing the dwell time of the piston within the combustion chamber. Currently combustion engines (especially diesel combustion engines) have a fixed crank and conrod which serve to control the motion of the piston as it cycles up and down within the piston chamber (the cylinder). The shape and profile of the crankand conrod are centred off a true vertical axis to cause the piston to “cycle” and increase the piston dwell time atTDC (top dead centre) and BDC (bottom dead centre) within the piston chamber. These dwell times are adjusted and set by the length of the conrod (gudgeon-pin to conrod bearing) and the distance from the centre of the crankshaft to the big end journal. This off-centre system helps achieve an optimum dwell time. The longer the “dwell time” the longer the period the fuel / air mixture is held in compression at the point of ignition and the more torque and efficiency the engine exhibits at the point of combustion. However, this can lead to a suboptimal burn of fuel, if the dwell time is too short and therefore allowing partially burnt fuel to pass out the cylinder chamber once piston is on its exhaust stroke (after peak dwell and the combustion stroke). The description below presents a novel system to increase the maximum dwell time.

[0003] According to the present disclosure, there is provided an internal combustion engine comprising a crankshaft having at least one associated cylinder chamber for rotating the crankshaft. Each cylinder chamber is configured with: at least two crank big end journals associated with the respective cylinder chamber; and at least two variablelength conrods, each conrod being independently connected to one of the corresponding crank big end journals and operable to extend into and retract from the cylinder chamber during operation, such that, as the conrods extend and retract throughout a piston cycle, a first of the conrods lags behind a second of the conrods; wherein, during the compression stage of a piston cycle of a given cylinder chamber, the second conrod reaches full extension while the first lagging conrod remains partially extended, and as the first conrod reaches full extension, the second conrod contracts, thereby increasing the dwell time of a piston at or near top dead centre.

[0004] The crank big end journals may be offset relative to each other to facilitate the complementary extension and retraction of the variable-length conrods during a piston cycle of a given cylinder chamber.

[0005] The at least two variable-length conrods of the or each cylinder chamber may share a common gudgeon pin that transfers load from the piston to the crankshaft.

[0006] The system works usin s key components. One is a cranks haft with two conrods within the area beneath each cylinder chamber. This means that two conrods will share a single gudgeon pin (specialist materials may be required for different engine specifications, in some cases custom piston design may also be needed) to connect the two variable conrods to the piston. Therefore allowing one to take the load from the piston (above) onto the two big end crank shaft journals (below a single cylinder). The crank shaft may require specialist materials depending on the engine specifications, inorder to sustain increased loads to achieve a comparable outcome. The second and third key features, are two, variable length conrods. The differing length conrods (both fixed independently into each of the twin crankshaft big end journals) means that one of the conrods extends while the other is shortened (and vice versa) to give an increased dwell time at BDC and TDC.

[0007] This varies from conventional combustion engines which exclusively rely on a single conrod servicing each piston / piston head within each cylinder chamber.

[0008] The benefits of the technology include increased fuel efficiency from the prolonged form a more efficient combustion due to the increased dwell time. Therefore creating more power out of the same engine.

[0009] Figs. A, B, C and D show the system when connected up to a piston (Part 1). As the piston descends down the bore it pushes on the variable conrod top eye (Part 6) through a gudgeon pin (part 4). This passes the load to the bottom half of the variable conrod (from part 6 to Part 5) when part 6 of the variable conrod is in its lowest position. This load is then transferred to the crank through the conrod big end bearingas seen in Fig’s G and H as (Part 7). Then the force is transmitted onto the crank big end journals as seen in (Part 10), (Part 11) in Figs. J and L.

[0010] This system focuses on utilising the wasted energy from the combustion of fossil fuels, especially (but not limited to) diesel. It does this by increasing the piston dwell time at and after TDC. This is to reduce the amount of inefficient combustion happening after TDC. This is done by having two variable conrods (as seen in Figs E, F, G, H and labelled as part 5, part 6 in Fig D). The two variable conrods are connected to a crank with two different crank big end journals for the same cylinder as seen in Fig J, Fig L labelled as part 10, part 11.

[0011] With these parts fitted to a piston (as seen in Fig A, B, C and D), there will be an increase in the piston dwell time at TDC. This is because as each variable conrod extends it holds the piston at TDC, with the combustion load being passed sequentially from one conrod to the second as the crankshaft rotates. This happens by allowing part 6 of the first variable conrod to extend away from part 5. Consequently, then allowing part 6 of the second variable conrod to bottom out on part 5, enabling the second variable conrod to support the load of the combustion.

[0012] The form, profile and distance between the crankshaft big end journals is key to making this all happen and the choice of materials used to form the crankshaft is important and depending on the engine size and packaging different specialist martials may be required. It does this by having two crank big end journals per piston which are offset to each other. This can be seen in Fig J, Fig L, parts 11,12. These crank journals attach to the variable conrods via the standard big end bearing (as seen in FigG, Fig H labelled 7). This allows the second variable conrod to reach its TDC later than the first variable conrod. The effect of this means that the first variable conrod will push the piston up to TDC, then the second variable conrod will support the load of the piston coming down from TDC.Then the crank continues to rotate and the cycle repeats.

[0013] The variable conrods cycle in a sequenced tandem to each other, one arriving at full extension whilst the second is not, and the second then arriving at full extension as the first contracts which therefore allows for the increased dwell time, at the top of the pistons’ stroke.

[0014] Alternatively, the crankshaft may be designed with more than two crank big end journals per cylinder, further improving the control over piston motion. By utilizing three or more crank big end journals, it is possible to distribute the load more evenly across multiple variable-length conrods, thereby reducing mechanical stresses and potentially improvingthe durability and efficiency of the engine.

[0015] The length of the variable-length conrods may alternatively be adjusted by means other than offsetting their respective crank big end journals (part 11 and part 12) orchanging the size of part 6, for example, by integrating hydraulic / pneumatic actuators or an electromechanical length control system into the conrod structure.

Claims

Claims1. An internal combustion engine, comprising:a crankshaft having at least one associated cylinder chamber for rotating the crankshaft, each cylinder chamber being configured with:at least two crank big end journals associated with the respective cylinder chamber; andat least two variable-length conrods, each conrod being independently connected to one of the corresponding crank big end journals and operable to extend into and retract from the cylinder chamber during operation, such that, as the conrods extend and retract throughout a piston cycle, a first of the conrods lags behind a second of the conrods; wherein, during the compression stage of a piston cycle of a given cylinder chamber, the second conrod reaches full extension while the first lagging conrod remains partially extended, and as the first conrod reaches full extension, the second conrod contracts, thereby increasing the dwell time of a piston at or near top dead centre.

2. An internal combustion engine according to claim 1 , wherein the crank big end journals are offset relative to each other to facilitate the complementary extension and retraction of the variable-length conrods during a piston cycle of a given cylinder chamber.

3. An internal combustion engine accordingto one of claims 1 or 2, wherein the at least two variable-length conrods of the or each cylinder chamber share a common gudgeon pin that transfers load from the piston to the crankshaft.

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