Variable compression ratio apparatus
A variable compression ratio apparatus, which is provided to an engine rotating a crank shaft upon receiving combustion power of a mixture from a piston for changing a compression ratio of the mixture, may include a connecting rod transferring combustion power of the mixture received from the piston to the crankshaft, and including a small end rotatably connected with the piston and a large end forming a circular hole, a crank pin, an eccentric cam disposed to be concentrically rotatable in the hole of the large end, an eccentric link at which the eccentric cam is disposed at a first end, a variable link having a first end rotatably connected with a second end of the eccentric link, a control link having a first end rotatably connected with a second end of the variable link, and a control shaft controlled by a controller and rotated together with the control link.
1. A variable compression ratio apparatus provided to an engine rotating a crankshaft upon receiving combustion power of a mixture of fuel and air from a piston for changing a compression ratio of the mixture, the variable compression ratio apparatus comprising:
a connecting rod transferring the combustion power of the mixture received from the piston to the crankshaft, and including a small end rotatably connected with the piston and a large end including a first hole for rotatable and eccentric connection with the crankshaft;
a crank pin disposed at the crankshaft;
an eccentric cam disposed to be concentrically rotatable in the first hole of the large end for eccentric insertion and rotatable connection of the crank pin in the first hole;
an eccentric link including a first end at which the eccentric cam is disposed to rotate together with the eccentric cam;
a variable link having a first end rotatably connected with a second end of the eccentric link;
a control link having a first end rotatably connected with a second end of the variable link; and
a control shaft disposed at a second end of the control link and controlled by a controller to be rotated together with the control link,
wherein the eccentric cam comprises:
a main body at which the eccentric link is formed or disposed, and at which a first part of a second hole into which the crank pin is inserted is formed; and
a sub body at which a second part of the second hole into which the crank pin is inserted is formed, and
wherein a sub body insertion space is formed in the main body and the sub body is disposed in the sub body insertion space, and
wherein the sub body is formed in a semicircle shape and the sub body insertion space is formed in a shape corresponding to the sub body.
2. The variable compression ratio apparatus of claim 1 , wherein the rotation of the control link rotating together with the control shaft rotates the eccentric link through the variable link.
3. The variable compression ratio apparatus of claim 1 , wherein the control shaft is controlled by the controller to rotate according to driving conditions of the engine.
4. The variable compression ratio apparatus of claim 1 , wherein the sub body insertion space is formed in a shape depressed along a radial direction from an external circumference of the eccentric cam.
5. The variable compression ratio apparatus of claim 1 , wherein the second hole into which the crank pin is inserted is formed by insertion of the sub body of the eccentric cam into the sub body insertion space of the main body.