Patent GB-628550-A (GB)
Title: A system for synchronising the speeds of two or more motors
IPC: H02P5/50
Filed: 1946-05-02
Abstract: 628,550. Fluid-pressure servomotor-control systems. REGIE NATIONALE DES USINES RENAULT. May 2, 1946, No. 13416. Convention date, May 24, 1940. [Class 135] [Also in Group XXXV] A system for synchronizing the speeds of two motors by aligning the speed of one of them to that of the other, either by accelerating the slower or by slowing down the more rapid, comprises a comparing device embodying two elements, each of which is adapted to be energized in accordance with the speed of one of the motors by means of a generator which is adapted to be driven by a motor, the effect of said generator on the corresponding element of the comparing device being proportional to the speed of the appropriate motor, and the effect of the comparing device being to move, in the desired sense, a control member actuating a servomotor controlling the supply to the motor, the speed of which is to be aligned to that of the other. If one of the motors 1 or 1<SP>1</SP>, which may be Diesel engines, operates at a higher speed than the other, the slower motor is accelerated until the speeds are substantially re-aligned. The motors are controlled by rods 3, 3<SP>1</SP>, which adjust the output of pumps 2, 2<SP>1</SP>, supplying fuel to the motors. The rods are driven by compressed air cylinders 4, 4<SP>1</SP>, movement of the pistons of which is restricted by springs 10, 10<SP>1</SP>, and the mechanical resistance of the actuated members, so that the pistons take up predetermined positions corresponding to a given pressure in the air-supply line 5. Tachometer generators 6, 6<SP>1</SP>, are mechanically coupled to the motors and are electrically connected to supply solenoid coils 7, 7<SP>1</SP>, respectively, of a speedcomparison device, the arm 8 of which is in a neutral position when the motor-speeds are equal. When the speed of the motor 11, for example, increases, the arm 8 is moved to close contacts 13 and energize the operating-coil of an electrically-operated valve 9, so admitting air to an auxiliary cylinder 15. The rod 3 is thereby moved to accelerate the motor 1 until its speed becomes substantially equal to that of the other motor, and the arm 8 is returned to its neutral position. Alternatively, auxiliary cylinders 15, 15<SP>1</SP>, may both be normally operative, and the energization of one of the valves 9 or 91 cuts off the air supply to the appropriate cylinder so moving the speed-control gear to a lower speed position. By these means, when one of the motors tends to over-speed it is decelerated until its speed equals that of the other motor. This result may also be obtained by arranging that the auxiliary cylinders 15 and 15<SP>1</SP> operate to reduce the speed of the appropriate motor when supplied with air under pressure. A third motor may be synchronized by employing another speed-comparison device similar to that shown, a coil of which is connected, in parallel with the coil 7<SP>1</SP>, across the armature of the tachometer generator 61, the other coil of said additional speed-comparison device being energized from the armature of a tachometer generator coupled to the third motor. Similarly, a greater number of motors may be synchronized by a suitable connection of the operating-coils of the comparison devices. In these arrangements some of the tachometer generators may supply only one operating-coil, and other may supply a plurality thereof, resistors are therefore connected across the lightly-loaded generators in order to ensure uniform operation.