Патент USA US2403605код для вставки
July 9, 1946. 2,403,605 R. N. LESNICK SPEED AND ACCELERATION RESPONSIVE DEVICE Filed July 1, 1942 . 0 uW z71/ (5 /d 9_ z / F/. 1m31k7 ||m1w”‘ m@Z12:Ih / P./ 5 w M v ‘Mn 0 mm J L MM 8 . mm. 95 \ J w .1 a A no1 6ow .»um‘#1m?/ O .F 0 M P. 0 y . 3 c.. . 5 HM 2 8 N. A “m. L r _ ., d .m .50 Gttomeg ' 2,403,605 Patented July 9, 1946 UNITED STATES PATENT OFFICE 2,403,605 SPEED AND ACCELERATION RESPONSIVE ‘ DEVICE Robert N. Lesnick, Camden, N. 1., vass'lgnor to Radio Corporation of America, a ‘corporation oi" Delaware Application July 1, 1942, Serial No. 449,231 3 Claims.‘ (Cl. 172-239) 1 This invention relates to speed and accelera tion responsive devices and more particularly to systems for producing displacement or opera tion of acontrcl device in response to-the speed or acceleration, or both, of a rotating shaft. _ Speed and acceleration responsive devices of ' this type iind application in servo systems or vfol low-up systems such as are used to move a rel 2 not exactly alike, or vary di?crently with tem perature or age, the springs it and 20 maybe arranged to bear against stops 22 on the support-, ing member 2i. The spring arrangement illus trated will accommodate angular displacements oi the shalt it of approximately ten degrees in either direction from the position or static equl- - librium. If lawn-displacements are, required, a modi?ed spring structure or suitable gearing may atively massive object in accordance withthe motion of a relatively small control device, In ‘til The orbit sears 23 oi the differential 8 are ro certain cases, it is desirable to add to the-elfect tatably mounted on radially, extending shafts 25 of the control device an auxiliary factor which is a function of the speed or acceleration of the . which are secured to a ring 21. The ring 21- may be of relatively massive construction in order to driven object, in order to compensate lag or hunt ing of the driven object with respect to the con 15 function as a ?y wheel or inertia load, as here inaiter described. Radlalvanes 29 may be pro trol device. vided on the surface of the ring l‘! to provide a Accordingly it is an object of this invention to frictional load on the system by air drag, orv provide an improved method of and means for by similar action in any suitable'?uld in which deriving a displacement component related in magnitude and direction vto the ‘angular. veloc 20 the device may be immersed. vThe vanes 28 may. be omitted and sliding friction means substitut ity or acceleration, or both, of a rotatable shaft. ed, such as brake shoes 42 bearingin the ring It is a. further object to provide an improved 21, as illustrated in Fig. 3. Another alternative means for correcting the errors inherent in cer is to provide the ring 21 with a radial ?ange of tain types of servo systems. conductive material, and produce an eddy cur These and other and incidental objects will rent drug related to the speed by means of mag become apparent to those skilled in the art upon nets, as in the well known watt-hour meter con consideration of the following description, with struction. ‘ reference to the accompanying drawing, in which ' The operation of the device is as follows; Ro Fig. 1 is a side elevation, partly in section, of a speed and acceleration responsive device con 30 tation of shaft l imparts to the gear ‘I an equal motion which is divided by- well known di?eren structedaccordinglto the invention, Fig. 2 is a tlal action between the shaft l3 and the ring 21 view through the section 2-2 of Fig. 1, Fig. 3 inversely as they tend to. oppose' motion. The shows a modi?ed speed-responsive means, and motion of the shaft I2 is opposed by one of the Fig. 4 is a schematic diagram of a servo system embodying the invention. 35 springs Ii and 20, and that of the rind 21 is op posed by the inertia force of the ring and the Referring to Fig. l, a shaft I is driven at any frictional force against the vanes 28. The spring predetermined angular velocity and acceleration ‘force is a vfunction of the angular displacement by a device 3, which may be an electric motor, in of the shaft II, and the inertia and frictional accordance with the operation of controlling means associated with said device. The shaft 1 40 forces on the ring 21 are functions respectively of the angular acceleration and angular velocity may be connected with a mechanical load gen of the ring. Thus the device functions as a yield-. erally designated by the block ll in the draw able coupling between the shaft; 1 and I3 with ing. The shaft 1 is also connected to a gear ‘I components responsive to the acceleration and to of a differential 9. ' A corresponding gear H at the other side of the diiferentlal i is connected 46 the velocity of the shaft] to rotate the shaft l2 against the spring restraining force. . ‘through a shaft II to a control device (not The shaft M will be rotated to an angular po shown) which responds to movement of the shaft sition in which the spring force balances the‘ in l3 under the forces of springs l0 and inertia ertia and frictional torces on the ring 21. Hence forces of the means 2°! and 29 to control the 9.9- ' plicatlon of power to the motor I. A radial arm 50 the position of the shaft 13, and the control de vice ls related'to the annular acceleration and i7 is secured to the shaft 13 and extends between the'angular velocity of the shaft l. The exact two springs ll and 20 fastened on a fixed sup relations are determined by the moment of ln-l port 2| (Fig. 2). In order to determine posi ertla of the ring 21, the area and arrangement tively the equilibrium position of the arm l'l, of the vanes 20 or other frictional means. and the even if the characteristics of the two spring; are be employed. , ' _ v M _ _ 2,403,605 3 constants of the springs I9 and :0. These fac tors are all to be considered in the design of the system for any specific application. For example with the system initially at rest Referring to Fig. 4, an electrical servo system embodying the invention is illustrated. A pair of Belsyn type transformers 30 and ii are me chanically connected to a control shaft 31 and a wntrolled shaft IM respectively. The shaft :3 is arranged to be rotated by any desired means such as a manually operable crank 35. The shaft III is connected to a driving motor I03 and to a device 31 like the mechanism illustrated in Figs. 1 and 2 of the drawing. The mechanical load to be operated is represented by the block I05, also connected to the driving motor W3. A Selsyn transformer H5, similar to trans formers l0 and 3|, is electrically connected be tween corresponding windings of said transform era; the rotor, for example, of the transformer [l5 being connected to the stator of the trans former I0 and the stator of the transformer i ii being connected to the stator of the transformer II. The stator of the transformer H5 is main~ tained stationary, and the rotor is connected through a shaft llll, corresponding to the shaft it of Fig. 1, to the device 31. displacing the rotor of the transformer H5 by means of the device of Fig. 1 described above. , The rotor winding of the transformer 3| is ‘ the crank 35 is rotated through some predeter mined angle. Voltage applied to the transformer II from the A.-C. lines 39 is converted to three separate in-phase voltages which are applied to the stator of the transformer H5. The ampli tudes of these voltages with respect to each other l0 depend upon the angular position of the rotor of the transformer 3i. Corresponding voltages are produced in the stator of the transformer I I5 and as long as the rotor remains in its initial position with respect to the stator thereof, the 15 output of the transformer I I5 corresponds exactly to the output of the transformer 31 . This output is applied to the stator of the transformer 30, providing a resultant field through the armature thereof and inducing a voltage in the rotor wind 20 ing which corresponds in amplitude to the differ ence in the angular positions of the crank 35 and the output shaft IIH. This voltage is ampli?ed by the amplifier ll, causing the motor I03 to rotate toward a position corresponding to that 25 of the crank 35. As' soon as the motor I03 starts to rotate, the input shaft of the device 31 is rotated, causing the output shaft to rotate in the opposite direc lines 88. The rotor of the transformer 30 is con tion due to inertia and friction loading on the nected to the signal input circuit of an ampli?er 30 differential spider member. This causes the rotor and motor control device designated by the of the transformer H5 to move through an angle block 4:. The device if is also energized from which is a predetermined function of the accel the lines 38, and is arranged to control the motor eration and velocity of the driving motor I03, in accordance with the amplitude of the control altering the relationship between the three volt input voltage and its polarity with respect to a 35 ages in the output circuit of the transformer and voltage derived from the supply lines 89. hence advancing the angular position of the field The operation of the system of Fig. i is as fol in the transformer 30 ina direction opposite to lows. The output voltage of the transformer to the direction of rotation of the crank 35. This is amplified in the device 4!. If said voltage‘ is increases the magnitude of the control signal zero, the motor I0! is not energized. If the volt 40 applied to the ampli?er 4i, providing more ener use is not zero, the motor His is caused to rotate gization of the motor Hi3 and hence a greater and turn the rotor of the transformer 3i, chang torque than would normally be produced as a ing the voltages applied to the transformer H5 . result of the difference in angular position be and through it the voltages at the primary of tween the crank and the driving motor. Thus the transformer 30. The voltage at the secondary 45 upon starting, the inertia of the load is overcome of the transformer it depends on both the volt by increasing the total control signal in response ages impressed upon its primary, and the physical to the acceleration of the output shaft. If rota position of its rotor with respect to its stator. tion of the crank 35 is continued, the output shaft Thus the voltage at the input of the device 4| will rapidly assume the velocity of rotation of changes with the rotation of the motor I03 until the crank and as soon as acceleration ceases the it is again zero, whereupon the motor I03 stops rotor of the transformer I [5 will tend‘ to assume and the system remains at rest until unbalanced its initial position under the action of the springs energized with alternating current from supply by some outside force such as rotr Z'Jh of the l9 and 20. crank 35. In nearly all systems of this class, certain errors device 31 will continue to provide its original effect, maintaining an advance in the position of the field in the transformer 30 proportional to the velocity of the shaft IOI. Thus the mag_ nitude of the control signal is higher at the higher velocities of operation, although not directly pro are inherent. For example, a consideration of the ‘principles of operation shows that there must be some difference in the angular positions of the controlling and driven shafts in order to pro vide a difference in the two voltages compared in the device H and operate the motor. Hence the two shafts normally do not remain .in posi tional agreement while the system is in motion. Another and often troublesome effect is that of However the frictional load on the portional to either the displacement or the ve locity. Upon retardation of the crank 35 the inertia of the device 31 acts in the opposite direc tion from that during acceleration, reducing the resultant control signal applied to the amplifier "hunting,” oroverrunning and reversal of the M to a value which is less than the normal dis driven member about the point of positional agreement with the control shaft. Servo systems placement proportional signal, tending to reduce the energization of the motor more rapidly than the difference between the positions of the crank subject to such difficulties. 35 and the output shaft Jill ‘is reduced. At the It has been found that the above described 70 same time the frictional load on the device 31 defects may be partially or substantially elimi tends to maintain the control signal at a higher nated by adding to the control signal or equiva level in response to the velocity of rotation of lent force a quantity related in magnitude to the the shaft ID]. This component retains its orig velocity and acceleration of the driven member. inal sense although the acceleration component In the system illustrated in Fig. 3 this is done by 75 is reversed. Thus as the output shaft tends to of many types, as well as electrical systems, are 2,4033% 5 sponse to the displacement of said restraining overshoot, reversing the displacement signal, this reversed signal is materially reduced by the ve locity component, causing the shaft [ill to rotate member. ' 2. In a servo system comprising a control shaft. ’a driven shaft, means responsive to the differ» to its correct angular position more slowly so as to prevent overshooting in the opposite direction and further reversal. Thus the invention has been‘ described as an ence in the angular positions of said shafts to control a motor to drive said driven sliaf t toward positional‘ agreement with said control shaft, improved speed and/or acceleration responsive means responsive to the angularvclocity and acceleration of said driven shaft to produce an device, comprising mass and drag or friction ele ments driven through a differential having an 10 auxiliary control effect on said motor. including a differential connected between said driven shaft output shaft restrained by spring means. The and an auxiliary control shaft resiliently re spring force is balanced against the inertia and strained against rotation, anda mechanical load‘ drag or frictionforces, resulting in a displace- - connected to said differential to control the trans ment of the output shaft which is a function of the velocity and acceleration of the input shaft. An illustrative application of this device in an electrical servo system has also been described. I claim as my invention: 15 mission of-torque from said driven shaft through said differential to said auxiliary control shaft. 3. In a servo system including a driven shaft, a motor coupled to said shaft, and means for energizing said motor in response to a control 1. In a servo system including a, control shaft, a controlled shaft, means for comparing the an 20 input signal, angular displacement responsive means for producing an auxiliary signal in addi tion to said control input signal, differential gear ing including two shafts and a spider member, said shafts being connected respectively to said ' so as to drive said controlled shaft toward a posi tion corresponding to that of the control shaft, 25 driven shaft and to said displacement responsive means for deriving auxiliary forces related in means, and a mechanical load comprising fric magnitude and direction to the velocity and to tion and inertia elements coupled to said differ the acceleration of said controlled shaft compris ential spiderymember to cause rotation of said gular positions of said shafts, means for deriving a force related to the difference in said positions and applying said force to said controlled shaft displacement responsive means as the sum of ing differential means connected to said con trolled shaft and connected to drive a mechanical 30 predetermined functions of thepspeed and the load comprising inertia and friction elements against a resilient restraining member, and means for deriving said auxiliary forces in re acceleration of said driven shaft. ROBERT N. LESNICK.