An internal combustion engine with a lubrication path

Abstract

The present invention relates to a lubrication system for an internal combustion engine 100. The internal combustion engine 100 comprising an engine block 102, a crankshaft 104, an auxiliary shaft 118, and an oil path 120. The crankshaft 104 includes a crankpin 118 and a crank arm 110a. The crankshaft 104 is supported by the engine block 102. The auxiliary shaft 118 extending concentrically through the crankshaft 104 and having a centreline 128 coinciding with the crankshaft axis 112. The oil path 120 is disposed between the engine block 102 and the crankpin 110. The oil path includes a first oil channel 120a extending through the auxiliary shaft 118 in a longitudinal direction.

Description

TITLE OF INVENTION:AN INTERNAL COMBUSTION ENGINE WITH A LUBRICATION PATHTECHNICAL FIELD

[0001] The present subject matter relates generally to an internal combustion engine. More particularly but not exclusively the present subject matter relates to lubrication of one or more parts of the internal combustion engine.BACKGROUND

[0002] Nowadays, with the advancement in the technology, a variable compression ratio is used to adjust / change a compression ratio of an internal combustion engine. The internal combustion engines employing variable compression ratio permits a volume above a piston of the engine at a top dead centre to be changed / varied. The internal combustion engines running at higher loads need lower compression ratios to increase power, whereas the internal combustion engines running at lower loads need higher ratios to increase the efficiency of the internal combustion engine. The variable compression ratio facilitates in lower the fuel consumption while increasing the efficiency of the internal combustion engine.BRIEF DESCRIPTION OF THE DRAWINGS

[0003] The details are described with reference to an embodiment of an internal combustion engine along with the accompanying diagrams. The same numbers are used throughout the drawings to reference similar features and components.

[0004] Figure 1 exemplarily illustrates a cross- sectional side view of the internal combustion engine.

[0005] Figure 2 exemplarily illustrates a localized cross sectional side view of the crankshaft with the lubrication path.

[0006] Figure 3 exemplarily illustrates one or more one or more bushes used in the lubrication path.DETAILED DESCRIPTION

[0001] A variable compression ratio is used to increase the efficiency of an internal combustion engine while ensuring a lower fuel consumption. The Variable Compression Ratio (hereinafter to be referred as ‘VCR’) is a ratio by which fuel / air mixture is compressed before the fuel / air mixture is ignited. There are different ways to vary the compression ratio already known in the art. In a known prior art, a Saab Variable Compression (SVC) lowers a cylinder head closer to a crankshaft, which alters the compression ratio. It is done by replacing a typical one part engine block with a two part unit, with the crankshaft in a lower block and the cylinders in an upper portion. The drawback of such mechanism is that moving mass of SaaB VCR is very high. Also, complex pivot arrangement is used to achieve changes in compression ratio.

[0002] In yet another known art, the piston top exceeds a top of the cylinder by a given amount, this volume must be subtracted from the combustion chamber volume, which will increase the compression ratio. However, the piston position directly affects piston-to-head clearance, so caution and precision is to be taken at the time of manufacturability so that the piston-to-head clearance stays within the specification and is not affected, which may lead to a defective engine. Achieving this piston-to-head clearance is very difficult during manufacturability and there are high chances of manufacturing of defective parts.

[0003] In yet another known art, a VCR system is provided which includes one or more gears assembled in a crankshaft assembly. The one or more gear includes an eccentric gear which is located between a piston and a crank pin. A VCR gear, the eccentric gear, and an intermediate gear are connected together to form the VCR system. To vary the compression ratio, the VCR gear is adjusted by moving the piston up and down to change the volume and thus changes the effectivecompression ratio in the combustion chamber. However, these gears, and other parts of the internal combustion engine need to be lubricated for durability, as with time, the gears and the other parts will wear and tear. The working of these gears of the VCR system and the other parts and the other parts may get affected and may not work smoothly if not lubricated properly.

[0004] In conventional system, an oil path is provided at a magneto side of a crankcase which travels up to a needle bearing, passing through a crankshaft and a crankpin. The problem occurs when the oil lubrication path is at clutch side, more specifically when the oil lubrication path is to be made at the same side as that of a VCR (variable compression ratio) system, then the oil lubrication path becomes complex and difficult to manufacture. This is a problem in existing system in which multiple gears are provided on the clutch side of the crankcase, making it difficult to have oil path between the multiple gears. The presence of multiple gears results in space crunch for laying out the oil lubrication path. If the oil lubrication path is routed from the magneto side of the crankcase, the oil path will be long, complex, and will be difficult to manufacture in the internal combustion engine.

[0005] Further, in the variable compression ratio system, crankshaft actuation of an eccentric gear / bearing is through a VCR shaft, this shaft is arranged inside the crankshaft. In conventional engines, lubrication of connecting rod big end bearing is done by lubrication path through the crankshaft and the crankpin. Since there is an actuation shaft inside crankshaft of VCR system, oil lubrication path is required to ensure lubrication of the bearing.

[0006] The above-mentioned problems are very critical and therefore, effective lubrication of the gears of the VCR system is required to be carried out for proper functioning of the internal combustion engine with variable compression ratio. Thus, there is a need to overcome the above-mentioned problems and other problems of known art.

[0007] An objective of the present subject matter is to provide an effective and efficient lubrication of parts of an internal combustion engine, which maintains the durability of the engine and thus increases the life of the engine while avoiding failure of the parts and reduce the friction while the different parts of the engine isin operation. The embodiments of the present invention will now be described in detail with reference to an internal combustion engine along with the accompanying drawings. However, the present invention is not limited to the present embodiments. The present subject matter is further described with reference to accompanying figures. Wherever convenient, the same reference numbers are used throughout the drawings to refer to the same or like parts. While examples and features of disclosed principles are described herein, modifications, adaptations, and other implementations are possible without departing from the scope of the disclosed embodiments. It should be noted that the description and figures merely illustrate principles of the present subject matter. Various arrangements may be devised that, although not explicitly described or shown herein, encompass the principles of the present subject matter. Moreover, all statements herein reciting principles, aspects, and examples of the present subject matter, as well as specific examples thereof, are intended to encompass equivalents thereof.

[0008] As per an aspect of the subject matter, an internal combustion engine comprising an engine block, a crankshaft, an auxiliary shaft, and an oil path. The crankshaft includes a crankpin and a crank arm. The crankshaft is supported by the engine block and the crankshaft being rotatable about a crankshaft axis. The auxiliary shaft extending concentrically through the crankshaft and having a centerline coinciding with the crankshaft axis. The oil path is disposed between the engine block and the crankpin. The oil path includes a first oil channel extending through the auxiliary shaft in a longitudinal direction.

[0009] As per an aspect of the subject matter, the engine comprising a transmission system through which an eccentric member and the auxiliary shaft being drivably coupled to each other at a same side of the crank arm and the crankpin.

[0010] As per an aspect of the subject matter, the first oil channel in the auxiliary shaft communicates with a second oil channel in the engine block.

[0011] As per an aspect of the subject matter, the oil path includes one or more second passage, the one or more second passage is disposed at a predetermined distance from the one or more first passage.

[0012] As per an aspect of the subject matter, the first oil channel in the auxiliary shaft communicates with a third oil channel disposed in the engine block through the crank arm and the crankpin.

[0013] As per an aspect of the subject matter, the first oil channel in the auxiliary shaft extends concentrically through the auxiliary shaft.

[0014] As per an aspect of the subject matter, the at least one of the one or more first passages and the one or more second passages extends radially from the crankshaft axis. One or more annular groove is located in an outer surface of the auxiliary shaft, the one or more first passages and the one or more second passages forms an opening.

[0015] As per an aspect of the subject matter, the opening receives one or more first bushes to connect the one or more first passages with the second oil channel and the one or more second bushes to connect with the third oil channel. The one or more first passages and the one or more second passages includes the one or more annular groove.

[0016] As per an aspect of the subject matter, the one or more first bushes and the one or more second bushes are provided with one or more o-ring to seal the oil path. The one or more first bushes are press fitted in a cover clutch and the one or more second bushes being press fitted in the crankshaft.

[0017] As per an aspect of the subject matter, the transmission system is adapted so that under operating conditions the bearing rotates with respect to the crankpin at a half speed of a speed of the crankshaft with respect to the engine block and in opposite direction of rotational direction of the crankshaft with respect to the engine block in an event that the auxiliary shaft having a fixed position with respect to the engine block.

[0018] As per an aspect of the subject matter, the transmission system is formed by an eccentric member gear being an external gear provided at the bearing, an auxiliary gear is an external gear provided at the auxiliary shaft and an intermediate gear is an external gear being rotatably mounted to the crankshaft. The intermediate gear meshes with the auxiliary gear and the eccentric member gear.

[0019] As per an aspect of the subject matter, the intermediate gear is a two-stage gear, having a first intermediate gear which meshes with the eccentric member gear and a second intermediate gear which meshes with the auxiliary gear. The first intermediate gear and the second intermediate gear being located next to each other in an axial direction.

[0020] Fig.l exemplarily illustrates exemplarily illustrates a cross- sectional side view of the internal combustion engine 100. Fig. 1 shows an embodiment of a four- stroke internal combustion engine 100 according to the invention. The engine 100 comprises a crankcase 108 which supports a crankshaft 104 through a bearing 106. The crankcase 108 is divided into a left- side crankcase 108a and a right-side crankcase 108b. The crankshaft 104 includes a crankpin 110 which is located between two crank arms 110a and is rotatable with respect to an engine block 102 about a crankshaft axis 112. The crankshaft 104 includes at least a central main portion, the crankpin 110 and a crankshaft web (not shown), where the crankshaft web is located between the central main portion and the crankpin 110. One or more piston 116 is rotatably connected to a first end of the one or more connecting rod 114. The engine 100 comprises an eccentric member (not shown) which is rotatably mounted on the crankpin 110. The eccentric member is provided with the bearing 106 which is disposed eccentrically with respect to the crankpin 110. The bearing 106 has an outer circumferential wall which bears a big end of one or more connecting rod 114. One or more piston 116 is rotatably connected to a first end of the one or more connecting rod 114.

[0021] Fig.2 exemplarily illustrates a localized cross sectional side view of the crankshaft 104 with a lubrication path 120. Fig.3 exemplarily illustrates one or more one or more bushes used in the lubrication path 120. For brevity, fig.2 and fig.3 shall be discussed together. Hereinafter, oil path and lubrication path may interchangeably used 120. An auxiliary shaft 118 is provided inside the crankshaft 104. The auxiliary shaft 118 extends concentrically through the crankshaft 104 and having a centreline 128 coinciding with the crankshaft axis 112. The crankshaft 104 includes the crankpin 110 and the crank arms 110a, and the crankshaft 104 is supported by the engine block 102. The crankshaft 104 is rotatable about thecrankshaft axis 112. A transmission system is provided through which an eccentric member (not shown) and the auxiliary shaft 118 being drivably coupled to each other at a same side of the crank arm 110a and the crankpin 110. The oil path 120 is disposed between the engine block 102 and the crankpin 110. The oil path 120 includes a first oil channel 120a which extends concentrically through the auxiliary shaft 118. A third oil channel 120c is disposed between the engine block 102 and the crankpin 110. The auxiliary shaft 118 has a first passage 122 through which the first oil channel 120a communicates with a second oil channel 120b in the engine block 102 and a second passage 124 at a pre-determined distance from the first passage 122 through which the first oil channel 120a communicates with the third oil channel 120c through one of the crank arms 110a and the crankpin 110. However, it is to be understood that there is no limitation on the number of oil channels of oil path 120 and thus it is not restricted and can be less or more than three oil channels, as mentioned in the embodiment above. At the locations of the auxiliary shaft 118 where the respective first passage 122 and second passage 124 form openings to an outer surface thereof, annular grooves 126 are formed such that the oil channel continuously communicates with the second oil channel 120b and the third oil channel 120c through the crank arms 110a and the crankpin 110. Under operating conditions oil is transported from an oil pump (not shown) through the second oil channel 120b to the first oil channel 120a and then to the third oil channel 120c and from there in radial direction to the bearing 106 in order to lubricate the above mentioned parts.

[0022] The oil path 120 is connected to one or more bushes 130. One or more first bush 130a of the one or more bushes 130 is disposed inside the first oil channel 120a created inside the auxiliary shaft 118 at a first end, and at a side of the second oil channel 120b. The other end of the first oil channel 120a has one or more second bush 130b connected to it and is disposed at a side of the third oil channel 120c. There are one or more passages which includes a first passage 122 and a second passage 124 at both the ends of the first oil channel 120a which connects the first oil channel 120a with the one or more bushes 130a and 130b at both the ends. The opening near the first end of the first oil channel 120a is screwed to seal the opening.The third oil channel 120c is provided partially in the crankshaft 104 and partially in the crankpin 110 so that the third oil channel 120c extends to reach the bearing 106. The one or more bushes 130 are used for sealing and for minimum clearances. Due to some clearances between the one or more bush 130 and the first oil channel 120a, leakage may happen, so to avoid the same, one or more o-ring (not shown) is placed to seal the same. Durability of the bearing 106 is improved because of the lubrication, improving the life of the crankshaft 104. Friction is reduced due to the lubrication. Cooling of the engine 100 is achieved by the flow of oil and the oil is cooled by natural means or forced cooling means.

[0023] The present invention provides one or more lubrication path 120 for the bearing 106 and any other part of the engine 100 to avoid any failure of any moving parts of the engine 100 while in operation. The lubrication of the one or more parts of the engine 100 improves the durability and life of the part as well as the engine 100. Lubricating the parts will reduce the friction and thus will help in maintaining the efficiency of the internal combustion engine 100. The oil flowing in the lubrication path 120 also ensures cooling of the parts in the vicinity of the flowing oil.

[0024] While the present disclosure has been described with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made, and equivalents may be substituted without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from its scope. Therefore, it is intended that the present disclosure may not be limited to the particular embodiment disclosed, but that the present disclosure will include all embodiments falling within the scope of the appended claims.List of Reference Numerals100: Internal combustion engine102: Engine block104: Crankshaft106: Bearing108: Crankcase108(a): Left side crankcase108(b): Right side crankcase110: Crankpin110a: Crankarms112: Crankshaft axis114: One or more connecting rod116: One or more piston118: Auxiliary shaft120: Oil path / Lubrication path120a: First oil channel120b: Second oil channel120c: Third oil channel122: First passage124: Second passage126: Annular grooves128: Centreline130: Bush130a: one or more first bushes130b: one or more second bushes

Claims

We claim:

1. An internal combustion engine (100) comprising: an engine block (102); a crankshaft (104), said crankshaft (104) includes a crankpin (110) and a crank arm (110a), said crankshaft (104) being supported by said engine block (102) and said crankshaft (104) being rotatable about a crankshaft axis (112); an auxiliary shaft (118), said auxiliary shaft (118) extending concentrically through said crankshaft (104) and having a centreline (128) coinciding with said crankshaft axis (112); and an oil path (120); wherein, said oil path (120) being disposed between said engine block (102) and said crankpin (110), said oil path (120) includes a first oil channel (120a) extending through said auxiliary shaft (118) in a longitudinal direction.

2. The internal combustion engine (100) as claimed in claim 1, said engine (100) comprising a transmission system, said transmission system through which a bearing (106) and said auxiliary shaft (118) being drivably coupled to each other at a same side of said crank arm (110a) and said crankpin (HO).

3. The internal combustion engine (100) as claimed in claim 1, wherein said first oil channel (120a) in said auxiliary shaft (118) communicates with a second oil channel (120b) in said engine block (102).

4. The internal combustion engine (100) as claimed in claim 1, wherein said oil path (120) includes one or more second passage (124), said one or more second passage (124) being disposed at a predetermined distance from one or more first passage (122).

5. The internal combustion engine (100) as claimed in claim 1, wherein said first oil channel (120a) in said auxiliary shaft (118) communicates with a third oil channel (120c) disposed in said engine block (102) through said crank arm (110a) and said crankpin (110).

6. The internal combustion engine (100) as claimed in claim 1, wherein said first oil channel (120a) in said auxiliary shaft (118) extends concentrically through said auxiliary shaft (118).

7. The internal combustion engine (100) as claimed in claim 4, wherein said at least one of said one or more first passages (122) and said one or more second passages (124) extends radially from said crankshaft axis (112), wherein one or more annular groove (126) being located in an outer surface of said auxiliary shaft (118), wherein said one or more first passages (122) and said one or more second passages (124) forms an opening.

8. The internal combustion engine (100) as claimed in claim 7, wherein said opening receives one or more first bushes (130a) to connect said one or more first passages (122) with said second oil channel (120b) and said one or more second bushes (130b) connect with said third oil channel (120c), wherein said one or more first passages (122) and said one or more second passages (124) includes said one or more annular groove (126).

9. The internal combustion engine (100) as claimed in claim 8, wherein said one or more first bushes (130a) and said one or more second bushes (130b) being provided with one or more o-ring to seal said oil path (120).

10. The internal combustion engine (100) as claimed in claim 9, wherein said one or more first bushes (130a) being press fitted in a cover clutch and saidone or more second bushes (130b) being press fitted in said crankshaft (104).

11. The internal combustion engine (100) as claimed in claim 1, wherein said transmission system being adapted so that under operating conditions said bearing (106) rotates with respect to said crankpin (110) at a half speed of a speed of said crankshaft (104) with respect to said engine block (102) and in opposite direction of rotational direction of said crankshaft (104) with respect to said engine block (102) in an event that said auxiliary shaft (118) having a fixed position with respect to said engine block (102).

12. The internal combustion engine (100) as claimed in claim 1, wherein said transmission system being formed by an eccentric member gear being an external gear provided at said bearing (106), an auxiliary gear being an external gear provided at said auxiliary shaft (118) and an intermediate gear being an external gear being rotatably mounted to said crankshaft (104), said intermediate gear meshes with said auxiliary gear and said eccentric member gear.

13. The internal combustion engine (100) as claimed in claim 12, wherein, said intermediate gear being a two-stage gear, having a first intermediate gear which meshes with said eccentric member gear and a second intermediate gear which meshes with said auxiliary gear, wherein said first intermediate gear and said second intermediate gear being located next to each other in an axial direction.

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