Patent ID: 7089671

Claim:
A circular saw comprising: a base plate; a saw blade assembly mounted on the base plate, the saw blade assembly including a rotatably driven saw blade; a lower blade guard coupled to the saw blade assembly and removably covering a portion of the saw blade protruding below the base plate, wherein the lower blade guard rotates about an axis of rotation, the lower blade guard including an annular sleeve portion disposed about the axis of rotation, a sectoral portion which extends radially from the sleeve portion behind the saw blade and an elongated connecting bar projecting radially from an upper edge of the sectoral portion; and an extension spring which has a longitudinal axis and is stretched between a first portion of the saw blade assembly and a top end of the connecting bar of the lower blade guard, wherein the extension spring is connected to the first portion of the saw blade assembly at a location that is below the axis of rotation of the lower blade guard, and wherein the top end of the connecting bar is located above the axis of rotation of the lower blade guard, the extension spring rotatably biasing the lower blade guard to a closed position in which the blade guard covers the saw blade, and the extension spring forms a substantially straight line extending from the first portion of the saw blade assembly to the top end of the connecting bar when the lower blade guard is in the closed position, wherein the connecting bar, at which the extension spring is connected to the lower blade guard, is selected such that the angle between the line from the connecting bar to the axis of rotation of the lower blade guard and the line of action of the tensile force of the spring gradually decreases as the lower blade guard is rotated from the closed position to expose the saw blade, wherein the lower blade guard is rotatable between the closed position and a fully open position through an intermediate position in which the extension spring comes into contact with the sleeve portion, the spring bending around the sleeve portion with further rotation of the lower blade guard so that a torque acting on the lower blade guard decreases once retraction of the lower blade guard has passed the intermediate portion as a result of the relative positioning of the connecting bar of the lower blade guard to the saw blade assembly.