Apparatus for opening and closing cover

摘要

An activating device (10) for a cover (92) has: a shaft unit (20) having a rotary shaft (21); an arm unit (40) which is coupled to the cover (92) and the rotary shaft (21); and an actuator (60) which drives the rotary shaft (21). The actuator (60) has: a motor (61) having a first output portion; a first reducer (62) having an input portion (62a) and an output portion (62b); and a second reducer (63) having an input portion (63a) and an output portion (63b). The reciprocal of a reduction ratio (R 2 ) of the second reducer (63) is larger than a quotient which is obtained by dividing a product by a torque (T R1 ) that is required for rotating the output portion (62b) when a torque is not applied to the input portion (62a), the product being obtained by multiplying a difference between a maximum torque (T L ) that is applied to the output portion (63b) when the cover (92) is opened, and a torque (T R2 ) that is required for rotating the output portion (63b) when a torque is not applied to the input portion (63a), with a ratio (· 2 ) of a torque that is a remainder of a torque applied to the output portion after subjecting to a mechanical loss due to the second reducer (63), to the torque applied to the output portion.