| 摘要 |
1,136,138. Ratchet clutches. S.S.S. PATENTS Ltd. 7 July, 1967 [20 July, 1966; 24 Aug., 1966], Nos. 32577/66 and 38022/66. Heading F2C. A synchronous self-shifting clutch comprising two rotary members, an intermediate sleeve splined to one of said members and carrying clutch teeth engageable with clutch teeth on the other of said members, and pawls on either the intermediate sleeve or said other member which engage ratchet teeth on the other member or the sleeve when the rotary members reach synchronism to initiate clutch engagement, has the engaging surfaces of the pawls and ratchet teeth inclined relative to the clutch axis so that the contact forces between them have an axial component to move the sleeve for clutch engagement, and as the clutch teeth approach full driving engagement their interaction disengages the pawls from the ratchet teeth. In Fig. 1, the ratchet teeth 5 have a helix angle of 35 degrees and the clutch teeth 2, 12 have a helix angle of 30 degrees, straight splines 9, 10 connecting the sleeve 11 to the input member 7. When the input member 7 reaches the speed of the output shaft 1, pawls 3 engage ratchet teeth 5 on the sleeve 11, causing the sleeve to be moved leftwards so that teeth 12 thereon move between teeth 2 on the shaft 1. Because of the different helix angles, as the sleeve moves leftwards, the teeth 12 engage the teeth 2 to generate an axial force urging the sleeve leftwards, and continued movement causes the pawls to move out of engagement with the ratchet teeth, so that on full clutch engagement, all the load is transmitted by the clutch teeth 2, 12. In a modification, the splines 9, 10 may be helical to assist clutch engagement. In Fig. 2, the clutch teeth 25 and the ratchet teeth 27 on a shaft 15 are combined as at 18, the clutch teeth 25 and clutch teeth 23 on the intermediate sleeve 22 being straight, while the ratchet teeth 27 and the faces 28 of pawls 24 have a helix angle of 10 degrees in the opposite sense to the helical splines 20, 21 between the sleeve 22 and the shaft 19. Thus as shaft 15 starts to drive shaft 19, both sets of helical surfaces urge the sleeve leftwards. In Fig. 3, clutch teeth 43 with a helix angle 30 degrees are combined with ratchet teeth 45 with a helix angle 35 degrees, as at 34, the intermediate sleeve being connected to its shaft by straight splines. |
