| 摘要 |
1,214,600. Controlling reactors. UNITED STATES ATOMIC ENERGY COMMISSION. 20 Nov., 1969 [18 Dec., 1968], No. 56760/69. Heading G6C. A nuclear reactor control rod drive assembly comprises: (a) primary motor means for delivering a variable speed drive; (b) primary transmission means for delivering the output of the primary motor means; (c) secondary motor means for delivering a constant speed drive; and (d) secondary transmission means for receiving drive from the secondary motor means and from the primary transmission means, and delivering a differential output, whose direction of output and rate of rotation are a function of its relative inputs, adjustment of the speed of the primary motor means determining the direction and rate of the differential output. Referring to Fig. 1, a cold type brake 16 is engaged and physically grabs and prevents rotation of a shaft 28 extending from primary motor 14 should the power source fail. Mounted integrally on shaft 28 is a ring gear 32 in a gear system 22, which system also includes idler gears 38 and a pinion gear 34. Pinion gear 34 is mounted on the end of a shaft 36 which passes through secondary motor 18 and carries a prime drive wheel 60 which supports three planet gears 61a engaged with internal teeth 52a of a flywheel ring gear 52. Ring gear 52, which is of large mass, is mounted on a hollow shaft 54 driven by the motor 18. Planetary gear system 24 is completed by a sun gear 66 mounted on the end of a shaft 68 which extends to form a ball screw 26. A control rod is connected to the ball screw 26 by a ball nut 74. In operation both primary and secondary motors 14, 18 are running continuously and with the gear ratios properly selected for gear systems 22, 24, motor 14 operating at 30 r.p.m. and motor 18 operating at 360 r.p.m., ball screw 26 is stationary. When it is desired to raise the control rod, motor 14 is increased in speed to 30À252 r.p.m. and sun gear 66 rotates 0À05 rev. for ech rev. of prime drive wheel 60. To lower the control rod, motor 14 is reduced in speed to 29À752 r.p.m. Motor 14 is a synchronous motor and the three speeds of 29À752, 30 and 30À252 r.p.m. are true synchronous speeds based on varying the number of poles in the stator, acting upon the rotor, with a 60 c/s. line frequency. Should cold brake 16 be actuated due to power failure, shaft 36 and prime drive wheel 60 are locked against rotation and there is a 5 : 1 speed increase for a rapid shut-down or scram. In the event of a power failure causing both actuation of cold brake 16 and failure of motor 18, the energy stored in flywheel ring gear 52 is sufficient to effect rapid shut-down. |
