| 摘要 |
A compression-vacuum percussion machine comprises, located in a casing (1), a cylinder (2) in which are mounted a striker (7) and a piston (3) separated from the striker by an air cushion (8), a crank (5) connected to the piston (3) and linked with a driving shaft (6) by means of a counterweight (10), whose center of gravity is offset in relation to a straight line (A-A) connecting the intersection points of the axes (O1 and O2) of the drive shaft (6) and the crank (5) with a plane perpendicular to the axis (O1) of the drive shaft (6). The projection of the counterweight (10) onto said plane is constituted by a figure located on that plane and having two sections (12, 13), one (12) of which is oriented symmetrically in relation to the straight line (A-A) passing through the intersection points of the axes (O1 and O2) of the drive shaft (6) and the crank (5) with a plane perpendicular to the axis (O1) of the drive shaft (6), whereas the center of gravity (b) of the other section (13) is located on a line (B-B) rotated through an angle ( beta ) 45-90 DEG in relation to said straight line (A-A) in the direction (w) of rotation of the crank (5). The masses m1 and m2 of the parts (12, 13) of the counterweight (10), which correspond to said sections of the figure, are related by the following equation: m1r1 = m2r2/K, where r1 and r2 are the distances between the intersection point of the axis (O1) of the drive shaft (6) with the plane perpendicular to said axis and the centers of gravity (a, b) of the parts (12, 13) of the counterweight (10) with corresponding masses m1 and m2 whereas K is 1-2. |
