Claims:We Claim:
1. An internal combustion (IC) engine (10) with a variable compression ratio, said IC engine (10) comprising :
- a cylinder (12) having a piston (14);
- a gudgeon pin (26) positioned at bottom of said piston (14);
characterized in that:
- said gudgeon pin (26) is eccentrically placed in a bearing at said bottom of said piston (14) ;
- a first connecting rod (16) ;
- a second connecting rod (18) having a passage, said first and second connecting rods (16,18) are connected to said piston (14) via said gudgeon pin (26);
said gudgeon pin (26) adapted to move to a maximum position in said bearing (28) based on a movement of said first connecting rod (16) when a fluid is pumped into said passage of said second connecting rod (18), to vary said compression ratio in said IC engine (10).

2. The IC engine (10) as claimed in claim 1, wherein a portion of said first connecting rod (16) comprising a shaft (24) is in fluid communication with said passage (22) of said second connecting rod (18).

3. The IC engine (10) as claimed in claim 1, wherein said shaft (24) of said first connecting rod (16), adapted to move in said passage (22) of said second connecting rod (18) based on a flow of said fluid.

4. The IC engine (10) as claimed in claim 1, wherein said fluid is pumped into said passage (22) of said second connecting rod (18) at the start of an intake stroke by a hydraulic circuit (30) .

5. The IC engine (10) as claimed in claim 1, wherein said gudgeon pin (26) adapted to move to a minimum position in said bearing (28) and said shaft (24) of said first connecting rod (16) moves downwards in said passage of said second connecting rod (18) , when said fluid in said passage (22) is returned to said hydraulic circuit (30).

6. The IC engine (10) as claimed in claim 1, further comprises a control unit (36) adapted to detect an additional eccentric volume in said cylinder (12), when said piston (14) moves from a top dead center to a bottom dead center at the end of said intake stroke.

7. The IC engine (10) as claimed in claim 1, wherein said control unit (36) adapted to alter said compression ratio of said IC engine (10) upon detecting said additional eccentric volume, at the end of a compression stroke.
, Description:Complete Specification:
The following specification describes and ascertains the nature of this invention and the manner in which it is to be performed.
Field of the invention
[0001] This invention relates to an internal combustion (IC) engine with a variable compression ratio.

Background of the invention
[0002] It is widely known that the performance of an internal combustion engine is proportional to the pressure reached within the combustion chamber thereof during the compression phase of the combustible mixture. Furthermore, it is also known that compression accelerates combustion and increases the thermal efficiency and piston speed, hence the need for the highest possible degree of compression. Compression ratio in IC engines defines to what factor the injected air/fuel mixture is compressed. For a given engine, the compression ratio is fixed. By varying the compression ratio, the volume of air/fuel mixture injected & finally to the volume it is compressed is varied.
[0003] Prior art patent application WO2016016202 discloses a method for switching an adjustable compression ratio of an internal combustion engine having an adjustment device for the adjustment of the adjustable variable compression ratio in at least one first cylinder and one second cylinder with a first compression ratio of the first cylinder and a second compression ratio of the second cylinder. In particular taking into consideration a mean pressure to be generated in the first cylinder, a first target compression ratio for the first cylinder and a second target compression ratio for the second cylinder are determined. The first target compression ratio differs from the second target compression ratio, and the first compression ratio and the second compression ratio are adjusted to the first target compression ratio and to the second target compression ratio respectively.

Brief description of the accompanying drawing
[0004] Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawing:

[0005] FIG. 1 illustrates an internal combustion engine in accordance with one embodiment of the invention;
[0006] FIGURES. 2 (a),2 (b),2 (c) illustrates a method of working of the internal combustion engine.

Detailed description of the embodiments
[0007] FIG. 1 illustrates an internal combustion engine 10 with a variable compression ratio accordance with one embodiment of the invention. The IC engine 10 comprises a cylinder 12 having a piston 14 and a gudgeon pin 26 positioned at bottom of the piston 14. The gudgeon pin 26 is eccentrically placed in a bearing 28 at the bottom of the piston 14. The IC engine 10 further comprises a first connecting rod 16 and a second connecting rod 18 having a passage 22. The first and second connecting rods (16,18) are connected to the piston 14 via the gudgeon pin 26. The gudgeon pin 26 adapted to move to a maximum position in the bearing 28 based on a movement of the first connecting rod 16 when a fluid is pumped into the passage of the second connecting rod 18, to vary the compression ratio in the IC engine 10.

[0008] Further the construction of the IC engine 10 and the components of the IC engine 10 is explained as follows. One end of the second connecting rod 18 is connected to a crankshaft 20. The rotation motion of the crankshaft 20 is converted into the reciprocation motion of the second and first connecting rods (16,18) , thus moving the piston up and down in the cylinder 12. The gudgeon pin 26 positioned in the bearing 28, moves from a minimum position to a maximum position based on the movement of the connecting rods (16,18). A portion of first connecting rod 16 is in fluid communication with a portion of second connecting rod 18 as shown in the figure 1. The first connecting rod 18 comprises a shaft 24 at the bottom portion, which is fixed into a depression at the top portion of the second connecting rod 18. The shaft of the first connecting rod 16, adapted to move in the passage of the second connecting rod 18 based on a flow of the fluid.

[0009] The IC engine 10 is connected to a hydraulic circuit 30. According to one embodiment of the invention, the hydraulic circuit 30 is a placed in proximity to the IC engine 10 in the vehicle. The hydraulic circuit 30 comprises a tank 32 holding a fluid and a pump 34 adapted to pump 34 the fluid into the passage of the second connecting rod 18 of the IC engine 10. The fluid is pumped into the passage of the second connecting rod 18 at the start of an intake stroke by the hydraulic circuit 30. The movement of the fluid into the second connecting rod 18 passage, further moves the first connecting rod 16, the gudgeon pin 26 and the piston 14. The IC engine 10 further comprises a control unit 36 adapted to detect an additional eccentric volume in the cylinder 12, when the piston 14 moves from a top dead center to a bottom dead center at the end of the intake stroke. The control unit 36 adapted to alter the compression ratio of the IC engine 10 upon detecting the additional eccentric volume, at the end of a compression stroke.

[0010] Figures 2(a), 2(b) & 2 (c) illustrates a method of working of the internal combustion engine. The IC engine works in a four-stroke engine cycle, an intake stroke, a compression stoke a power stroke and an exhaust stroke as known to a person skilled in the art. At the start of the intake stroke as shown in the figure 2 (a), the piston 14 move from top dead center (TDC) to bottom dead center (BDC) in the cylinder 12. The movement of the piston 14 causes low pressure in the cylinder 12. A hydraulic force is applied on the connecting rods (16,18) by pumping the fluid from the tank of the hydraulic circuit 30 into the passage of the second connecting rod 18. Due to the movement of the fluid into the passage 22, the shaft 24 of the first connecting rod 16 is moved upwards, which further pushes the gudgeon pin 26 to a maximum position in the bearing 28. At the end of the intake stroke, the fluid is returned to the tank of the hydraulic circuit 30 and the gudgeon pin 26 moves to a minimum position in the bearing 28 from the maximum position.

[0011] The shaft 24 of the first connecting rod 16 comes into contact with the bottom surface of the passage of the second connecting rod 18 as shown in the figure 2(b). Due to the above-disclosed movement of the gudgeon pin 26 in the bearing 28 and the shaft 24 of the first connecting rod 16, an additional eccentric volume is formed above the piston head in the cylinder 12. As known to a person skilled in the art, the compression ratio of the engine 10 is the combination of the displacement volume (distance from TDC to BDC in the cylinder 12) and the clearance volume above the piston head (when the piston 14 is in TDC position) as shown in the figure 2(b). In addition to the above two volumes, due to the arrangement of the two connecting rods (16,18) and the gudgeon pin 26 the bearing 28, the additional eccentric volume is formed above the piston head (when the piston 14 in in BDC position) at the end of the intake stroke. The total compression ratio of the cylinder is the combination of the displacement volume, clearance volume and the eccentric volume as shown in the figure 2(c). Due to the additional volume, the compression volume of the cylinder 12 during the compression stroke is increased which further increases the pressure and the combustion in the cylinder 12.

[0012]The above method is explained with an example. With the conventional arrangement of the gudgeon pin 26 and the connecting rod (piston 14 and the crankshaft 20), the total compression ratio is the sum of the displacement volume and the clearance volume. For instance, let the compression ratio with the conventional arrangement is 10, Vd (displacement volume) is 9 & Vc (clearance volume) is1. Now, with the additional connecting rod and variable position of the placement of gudgeon pin 26 the bearing 28, an additional eccentric volume (Ve) is achieved. For instance, if Ve is 2, then the total compression ratio of the cylinder is 12. With the new compression ratio, a higher pressure can be managed in the cylinder 12 and a higher combustion rate is achieved.

[0013] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.