US2605450A - Computer automatic reset - Google Patents

Description

J ly 1952 L. A. NETTLETON ET AL 2,605,450

COMPUTER AUTOMATIC RESET Tiled Jan. 7, 1946 2 SIIEETS-SHEET 2 FIG. 5

INVENTORS LEROY A. NETTLETON I HENRY S. OMMERSMR- ATTORNEY Patented July 29, 1 952 2,605,450 COMPUTER- AUTOMATIC RESET Leroy A. NettletomBrookline, and Henry S. Sommers, Jr., Belmont, Mass., assignors, by mesne assignments, tothe United States of America as represented'by the Secretary of the Navy Application'January 7, 1946', Serial No. 639,67

6 Clailris.

, 1 This" invention relates to synchros, and more particularly to synchros used to position auxiliary apparatus.

.fSynchros are well knownin the art-,and are usually encountered in data transmission systems. Whena driven element in'data transmission apparatus must be reset at the conclusion of'some operation to one certain position and held stationary at that point, mechanical power from some source other than synchros is usually necessary. Generally this source of power is a motor with associated gears or other driving mechanisms which necessarily complicate many systems using synchros. v

Therefore the general object of the; present invention is to provide for the utilization of a synchro, normally used for data transmission, as a motor to operate a driven element. I

It is a further object of the present invention to provide'means for switching a synchro so that .it may function to transmitdata, to operate as a motor, orto lock a driven element.

'These and other objects will be apparent from the following specification when taken with the accompanying, drawings in which:

Fig; 1 is a schematic'diagram of an embodiment types of. synchro-unitsmay be used. Magnetic switch 1 [operates upon the energization of magnet 24 whenswitch 23 is closed to connect the synchro to a data transmission circuit, and when switch 23 is openedthe synchro connects to magnetic switch l2. Magnetic switch I2 is operated .by magnet 25-and switch 22, the latterbeing controlled by cam l3. Switches l I and [2, although shown for convenience as magnetic switches, may be any other suitable switching apparatus.

Transformer [4 when connected to a suitable alternating voltage supply, furnishes a voltage pattern at its secondary suitable for locking a synchro unit in a stationary position in a manner known to the art.

to a stator winding of the synchro motor through Capacitor I5 is connected switch l6 which is operated bycam [1. The capacitor l5 causes the synchro motor to operate as a two phase induction motor, the running direction being determined by the position of switch l6. Cams l3 and Il are mechanically connected to the rotor of the synchro motor as indicated by dotted lines 18, I9, 20 and rotation reduction mechanism 2|. Magnetic switches II and [2 are powered by a suitable supply connected at terminals 28 and 29. A single phase alternating voltage supply, connected at terminals 26 and 21, and 26' and 21, furnishes power to synchro motor I0 and transformer M.

Fig. 2 illustrates a form of driven element mechanically connecting a cam system, the latter comprising cams l3 and H, to synchro motor [0. Thus, synchro motor III has its rotorshaft 30 operati g a small gear 3| which turns large gear 32. Large gear 32 turns shaft 33 on which cams I3 and I1 are mounted. These cams operate switches 22 and I6 respectively. Arrow 34 indicates a point on the periphery of large gear 32 which corresponds in position to the protrusion in cam l3. Arrow 35 is a point adjacent to large gear 32 so determined that if arrows 34 and 35 coincide, cam I3 operates switch 22. It may be further seen that switch It is operated one way or the other by cam ll depending on whether arrow 34 is in one or the other half region of large gear 32 as viewed in Fig. 2.

Fig. 3 illustrates an alternative driven element and cam system mechanically connecting synchromotor l0 and switches l6 and22. In this figure a single cam 40 replaces cam system [3, I! (Fig. 2). Cam 40, however, operates switches 16 and 22 in the same relation to large gear 32 as was shown to occur in Fig. 2.

Fig. 4 is a simplified schematic diagram showing how a pattern of voltage isapplied tothe windings of synchro motor I0 to cause it to lock in a particular stationary position. Transformer I4 is shown with conventional primary and tapped secondary windings. However the synchro may be directly connected to the line voltage supply, or an auto transformer may be used to provide a different excitation level. The process here shown is generally known in the art as locking at electrical zero or zeroing. This operation is effected when the switching elements of Fig. 1 are operated as will be described-below.

Fig. 5 shows in simplified form how the synchro I0 is made to operate as a two phase induction motor. Two stator coils are connected in series across the single phase alternating voltage supply 26 and 21, and the third stator-coil is connected to one side of the supply through series capacitor l5. This capacitor provides a shift in phase angle of the current through the third stator coil, so that the resulting efiect is two phase stator excitation. This phase shift may be accomplished by any other impedance element, as for example, a resistor or inductor, as is well understood. This two phase excitation produces a rotating magnetic field within the synchro, causing the rotor to revolve in the manner well known for induction motors. Changing the position of switch it reverses the direction of rotation because the time relations in the magnetic field are reversed. Induced currents in the laminated core of the synchros rotor act in the same manner as currents in the rotor of an ordinary motor. Hence the synchros rotor may be short circuited, open circuited, or closed through a resistance.

Referring again to Fig. 1, it Will be shown how the present invention may be used for data transmission, or as an apparatus for resetting and looking a driven element at a predetermined point. When synchro motor ii] is used for data transmission, it is connected by the switching system shown to a data transmission circuit by means or magnetic switch it when the movable arms thereof are thrown upward as viewed in Fig. 1. Magnetic switch H thus electrically disconnects all other parts of the circuit from the synchro motor.

When synchro motor is used to reset and lock a driven element (such as shown in Fig. 2 or 3) at a predetermined point, magnetic switch H is operated to disconnect the synchro motor from the data transmission circuits, and to connect the synchro motor to magnetic switch l2. This occurs when the movable switch arm of switch 1 I is thrown downward as viewed in Fig. 1. If switch 22 is not closed, switch [2 is in the downward position. Cam I? and associated switch it then connects capacitor Iii and the single phase alternating voltage supply at 26, 2? to synchro motor In through the contacts of switch 12, causing the synchro motor to act as a two phase induction motor. The direction of rotation of the synchro motor is determined by the position of switch It, which in turn is determined by which side of cam 17 operates switch it. Being connected as a two phase motor, synchro motor It) operates the driven element and the cam system in one direction or the other until the protrusion on cam 13 operates switch 22. Switch 22 then operates magnetic switch l2 and throws the movable arms thereof upward as viewed in Fig. i. This disconnects the synchro motor from capacitor 55 and the single phase supply, terminals 26 and 2?, and connects the synchro motor to transformer I l which furnishes a voltage pattern which looks the synchro motor in a single stationary position, as previously described in connection with the simplified zeroing circuit, Fig. 4.

Since changes may be made in th system described, and difierent embodiments of the Present invention may be made without departin from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted in an illustrative and not limiting sense, and therefore that the invention is to be limited only by the prior art and the spirit of th appended claims.

What is claimed is:

1. A synchro system comprising a synchro motor, a driven element mechanically connected to said synchro motor, a cam system mechanically connected to said driven element, a switching system mechanically operated by said cam system, a capacitor and source of voltage, said cam system operating said switching system and causing said synchro motor to be a reversible motor in all but one position of said cam system, and causing said synchro motor to be stationary at the remaining position of said cam system.

2. A synchro system comprising, a voltage source, a capacitor, a synchro, a driven element, rotation reduction means connecting said synchro to said driven element, a cam system connected to said driven element, and switching apparatus operated by said cam system, whereby said capacitor is switched into the circuit between said voltage source and a stator winding of said synchro, said synchro thereby being operative as a reversible two phase motor in all but one position of said cam system, and whereby said capacitor is switched out and voltages from said source selected to lock said synchro are applied to its stator windings at a predetermined remaining position of said cam system.

3. A synchro-automatioreset system comprising a receiver synchro, a voltag source, an impedance element, means connecting said impedance element with said synchro to said voltage source to operate said synchro as a reversible motor, a transformer energized from said source to provide a locking voltage pattern, and switching means operated by said synchro at a predetermined position to disconnect said synchro from said voltage source and said impedance element and connect said synchro to said transformer locking voltage pattern whereby said synchro is locked in said predetermined position.

4. A synchro automatic reset circuit for a synchronous data transmission system comprising a receiver synchro, a voltage source, a locking voltage pattern derived from said source, a phase shifting impedance, switching means disconnecting said synchro from said data transmission system and connecting said impedance with said synchro to said voltage source for operation of said synchro as a reversible motor, and means operated by said synchro at its zero position to disconnect said synchro from said impedance and voltage source and connect said synchro to said locking voltage pattern whereby said synchro is locked at said zero position.

5. In a synchronous data transmission system, an automatically reset circuit comprising, a receiver synchro, an auxiliary voltage supply, a transformer energized from said supply to provide a locking voltage pattern, means to operate said synchro as a reversible motor from said voltage supply, and switching means operated by said synchro at a predetermined position to disconnect said synchro from said voltage supply and to apply said locking voltage pattern to said synchro to lock said synchro in said position.

6. In a remote position indicating system in which the position of a synchronous transmitter is followed by the position of a synchronous receiver, an automatic zero reset circuit comprising, an auxiliary voltage source, a transformer energized from said source to provide a locking voltage pattern, a normally de-energized magnetic switch connecting said receiver to said transmitter, means energizing said switch to disconnect said receiver from said transmitter and to apply voltages from said source to operate 5 said receiver as a reversible motor, and switching means operated by said receiver at its zero position to disconnect said receiver from said voltage source and to connect said receiver to said locking voltage pattern whereby said. re- 5 REFERENCES CITED The following references are of record in the file of this patent:

Number Number 6 UNITED STATES PATENTS Name Date Hewlett et a1 Apr. 9, 1929 Read, Jr Mar. 12, 1946 FOREIGN PATENTS Country Date Germany Mar. 13, 1930 Great Britain June 17, 1938

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