Crankshaft

A crankshaft is in the oscillating piston machine linear ( translational ) movement of one or more pistons with the aid of connecting rods in a rotary movement around (or vice versa). The required for the conversion of the motion components together result in the crank drive. A distinction is built, ie composed of individual parts, and forged or cast, that is made ​​from one piece crankshafts.

Bearings, the crankshaft in the crankcase. The result cheek - crank pin - cheek is called the crank throw.

History

The first known machine in which using a rotary motion of the crankshaft and connecting rod was converted into a linear movement, is the Roman Hierapolis sawmill (3rd century).

Function

The crankshaft has the function of the piston forces that are transmitted via the connecting rod to take up, to convert it into a torque and transmit torque through the clutch to the transmission.

Crankshafts can also be stored vertically adjustable, so that is a variable compression possible. An eccentric bearing crankshaft bearings, the crankshaft is lifted. The advantage of a variable compression is in the partial load range by up to 25 % lower fuel consumption.

In order to conduct lubrication purposes engine oil within the crank piece to the main and connecting rod bearings, the crankshaft is hollow, the oil is supplied by a main bearing and then exits through holes in the shaft and the crank pin. In -built waves the main and connecting rod bearings are not plain bearing, but Rolling and these do not require high pressure oil pump, but are supplied by the oil mist in the cylinder crankcase lubricant.

Construction

A crankshaft consists of the following elements:

• Shaft journal. Those running in the basic storage (main storage), and define the axis of rotation of the shaft.
• Crank pins that receive the push rods ( conrods ). They describe a circular path during operation about the rotary axis of the crankshaft. The diameter of this circular path is exactly the stroke of the pistons.
• Crank webs that connect the crank pin with the shaft journal.
• The balancing counterweights are attached to the cheeks are usually used (eg, in -line engines ).

The rotating mass forces are complete and the oscillating mass forces of the first order are usually 50% balanced by attaching counterweights. However, this has the effect of increasing the weight of the crankshaft. A further reduction of oscillating mass forces of the first and second order is not carried out on actions on the crankshaft, but on the Lanchester balancer.