| 摘要 |
PURPOSE:To improve accuracy in working an extraction preventing device and ensure oiling by inserting a ball for preventing extraction of a spherical body of an connecting rod into a cylindrical hole provided in a piston sliding surface to have the center portion always in a cylinder. CONSTITUTION:A piston 3 is provided with an hollow portion 11 having a spherical portion 9 engaging a spherical body 5 of a connecting rod 4 in a kinematic pair of spherical surfaces and a cylindrical portion 10, and in the upper portion sliding in the cylinder 2 with a cylindrical hole 12 communicating to the cylindrical portion 10. A ball 13 having diameter approximately equal to the inner diameter of the cylindrical hole 12 is inserted into said hole 12 while the center portion is always located in the cylinder 2 and a portion of the cylindrical hole 12 is opened outside the cylinder 2 when the piston 3 is in the lower dead point. Thus, the ball 13 bears always against both the inner wall of the cylinder 2 and the spherical body 5 without springing out of the cylindrical hole 12 to improve accuracy in fitting dimension of the piston 3 and the connecting rod 4 for preventing play while flowing oil from the opening portion of the cylindrical hole 12 to lubricate the contact portion of the spherical body 5 and the ball 13. |
