| 摘要 |
<p>A speed reducer is proposed whose rollers are axially long relative to the axial length of its cage to extend its lifespan. The speed reducer includes an input shaft (7) and an output shaft (11) arranged coaxial with each other with their ends facing each other. Their ends facing each other are covered by a housing (1). The housing (1) supports an internal gear (3). An eccentric disk (9) is mounted on the end portion of the input shaft (7) so as to be located radially inwardly of, and rotatable relative to, the internal gear (3). A cage (13) is provided at the end of the output shaft (11) so as to be disposed between the internal gear (3) and a bearing (10) press-fitted on the radially outer surface of the eccentric disk (9). The cage (13) is formed with pockets (18) which are not equal in number to the number of the internal teeth (4) of the internal gear (3). A roller (19) is received in each pocket (18) so as to be rollable along the radially outer surface of the outer race of the bearing (10). The rotation of the input shaft (7) is transmitted to the output shaft (11) at a reduced speed ratio which is determined by the number of the internal teeth (4). An annular recess (21) is formed along the corner between the closed end surface (14) and the radially inner surface (20), of the cage (13). The recess (21) makes it possible to increase the axial length of the pockets (18) and thus the axial length of the rollers (19). This reduces surface pressure at the contact portions between the rollers and the pockets and thus increases the lifespan of the speed reducer.</p> |
