US1675333A - Control mechanism - Google Patents

Description

2 Sheets-Sheet 1 July 3, 1928.

' R. E. DE CAMP CONTROL MECHANISM Original Filed Nov. 11, 1919 a m III, ill|l Int. 7 I ll Ill in .n 1 min A "W l INVENTOR R0 5. De Camp. Y

ATTORNEY WITNESSES:

July 3, 1928. 1575.333

R. E. DE CAMP CONTROL MECHANI SM Original Filed Nov. 11, 1919 2 Sheets-Sheet 2 INVENTOR Ray/5.0:? Camp.

f/ X ATTORNEY -WITNESSES:

Patented July 3, 1928.

cairn STATES PAENT FFE.

RAY E. DE CAMP, OF GLENDALE, CALIFORNIA, ASSIGNOR TO W'ESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CQRPORATEON OF PENNSYLVANIA.

CONTROL MECHANISM.

Original application filed November 11, 1919, Serial No. 337.175.

August 25. 1923.

My invention relates to control mechanisms and particularly to devices which operate automatically to control the acceleration of electric motors.

This application is a continuation of my copending application Serial No. 337,175, filed November 11, 1919, for improvement in control mechanism.

My invention has for its object to provide a simple and eflicient device for automatically controlling the circuits of electric m0- tors.

My invention comprises a relay mechanism for controlling the operation of the usual accelerating switches of electric motors. The several movable contact members of the relay mechanism are automatically actuated to close the circuits controlled by them when they are released by a controlling electromagnet. The magnetic circuits or the actuating means for the respective contact members are so arranged as to per mit their operation in a desired sequence. If alternating current is employed, the movable contact members are so arranged. that the sequence of operation diiiers from the order in which the contact members are 10- caled. Adjacent contact members are not operated successively.

A second electromagnet controlsa bar or detent for rendering the first electromagnet eiiective only under predetermined conditions. lVhen the second electromagnet is energized below a predetermined degree, all of the. contact members are retained in their open positions regardless of the conditions obtaining in their respective magnetic circuits. lVhen the second electromagnet is energized to withdraw the bar or detent, the relays may close in accordance with the con ditions obtaining in their magnetic circuits, as determined by conditions in the motor circuits.

In the accompanying drawings, Figs. 1, 2 and 3 are, respectively, top plan, end and side views of a relay mechanism constructed in accordance with my invention; Fig. 4 is a side view of one of the electroinagnets; Fig. 5 is a diagrammatic view of circuits and apparatus ofa direct-current system of motor control embodying thev rela mecha Fig, 6 is a view, similar to ig. 5, of

-faatiug-c11rreiit system.

Divided and this application filed Serial No. 659,265.

Referring to Figs. 1, 2, 3 and 4, a base member 1, of suitable insulating material, supports a relay mechanism 2 that is arranged i'or use connection with an alternating-current circuit. The relay mechanism consists of four relays 3, 4r, 5 and 6, the stationary contact members of which are secured to the base member 1 and the n'iova'ble contact members of which are pivotally supported by a pin 7. Each of the movable contact members is biased to its closed position by a spring 8.

The movable contact members are controlled by an electromagnet consisting of a core member 9, a magnetizing coil 10 and a plate member 11 of magnetizable material that. is secured to the core member 9. A shading coil 12 is imbedded in that portion of the member .11 adjacent to each of the movable contact members. A second plate member '13, which is secured to the core member 9, has a portion extending at right angles to the main portion and para] lel to the base member 1 to constitute at tachi ng means for suitable spacing bolts that secure the magnet structure to the base member. A second portion of the member 1 3 is bent inwardly adjacent to the side of the coil 10 to constitute a material portion of the i'nagnetic circuit of the electromagnet.

The sequence of operation of the relays is secured by suitable adjustment of the air gaps of the several magnetic circuits and by adjustment of the springs 8 for biasing the relays to closed positions.

The movable contact members are controlled, also, by an electromagnet 14: which comprises a core member 15, a coil 16 and a movable armature member 17. A spring 18 normally retains the armature member 17 in the position in which it is illustrated in Fig. 4. A rod 19, which is rigidly secured to the armature member 17 and extends at right angles thereto. engages the supporting arms of the movable contact members and normally retains them in their open positions.

It may be assumed that the coil 10 is connected across a portion of the circuit of an electric motor. The coil is, in such case,

energized in accordance with the ditlerence' inpotential between the points of connection to such circuit. .lt he assumed Further that the coil 16 is connected directly across the line of a supply circuit, in which case, it is energized at substantially a constant voltage.

In the operation of the relay mechanism, the coil 16 is energized when its circuit is completed by the closing of the usual line switch. The armature 17 is drawn downwardly against the force of the spring 18, and the rod 19 is actuated to the left, as viewed in Figs. 1, 2 and 3, to release the movable members of the several relays.

The closing of the line switch has, however, caused a rush of current to flow through the circuit to which the coil 10 is connected, and the latter is energized to retain the movable contact members in their open or illustrated positions. When the difference in potential between the terminals of the coil 10 falls to a predetermined value, one of the contact members is released by the electromagnet and is actuated by its cor responding spring 8 to its closed position. It may be assumed, for example, that the relay 4 is the first to close.

A rush of current follows the closing of the relay 4, and the remaining relays are retained in their open positions until the coil 10 is energized below a second and'lower predetermined value, whereupon the relay 6 is closed in the manner described in connection with relay 4. The operations described above are repeated for relays 3 and 5, in order.

V hen the circuit controlled by the relay mechanism is opened, the coil 16 is de-energized and the spring 18 actuatos the armature member 17 and the rod 19 to their initial positions and thus effects the opening of the several relays 3, l. 5 and 6.

It will be noted, from the above-described sequence of operation, that the switches do not close in the same order as that of their mechanical arrangement. It has been found, in practice, that better results are obtained if adjacent switches do not operate successively. This condition is due to the fact that the magnetic circuits are so closely related as to interfere with the operation of adjacent contact members if they are adjusted to close at slightly different degrees of energization of the electromagnet. The order of operation is, therefore, arranged to occur in a sequence similar to that in which combustion occurs in the cylinders of a gas engine.

Reference may now be had to Fig. 5, in which is illustrated a direct-current system embodying a relay mechanism similar to that illustrated in Figs. 1, 2 and 3 but modilied slightly with respect to certain details. Instead of employing shading coils, as is the case when it is employed in connection with an alternatingcurrent circuit, adjustable pole pieces 19/1- are provided for each of the several movable switch members.

Line conductors 20 and 21 supply cur rent to an electric motor having an armature 22, a series field-magnetwinding and a shunt field-magnet winding A sectional starting resistor 25 is controlled by a series of successively operable switches 26, 27, 28 and 29 that are respectively provided with actuating coils 30, 31, 32 and 33. The several, actuating coils of the accelerating switches are in series with the relays 3, 4, 5 and 6 of the relay mechanism 2. A master switch 35 controls the circuits of the several actuating coils and of the actuating coil 36 of a line switch 37.

W'hen the master switch 35 is actuated to the right, as viewed in Fig. 5, to its second position, a. circuit is completed for the actuating coil 36 of the line switch 37, and the latter closesto complete the main circuit of the motor. An interlock 38, which is mechanically connected to the line switch 37 completes a circuit for the coil 16 of the relay. The latter coil is energized to draw the armature 17 downwardly against the force of the spring 18 and thus move th rod 19 out of engagement with the movable contact members of the relay. It may be assumed that the master switch 35 has been actuated to its final operative position by a quick movement. It will be understood, however, that the master switch may be actuated at any desired rate to correspondingly control the operation of the accelerating switches.

When the motor circuit is closed by the line switch, a rush of current traverses it, and the difference of potential across the resistor 25 is of such value as to cause the coil 10 to be energized to such degree. as to maintain the movable contact members in their initial or open positions.

When the motor has accelerated to such rate that the current traversii'ig the resist-or 25 has fallen to a predetermined value, the relay 5 closes to complete acircuit for the coil 30 which extends from line conductor 20 through conductor 39, master switch 35, coil 30, relay 5 and conductor 4-0 to line conductor 21. The switch 26 closes to shunt a section of the resistor 25 and a. second rush of currentiraverses the motor circuit.

When the current again falls to the predetermined value, the difference in potential across the remaining portion of the resistor 25 is such as to permit the closing of relay 3 and the latter closes to complete a circuit for the coil 31. This circuit is similar to that traced above in connection with the circuit of coil 30. The switch 27 then closes to shunt another section of the resistor 25. The operation is repeated and the relays 6 and 4 close in order. The switches 28 and lit) 29 close in succession to shunt the remaining sections of the resistor 25.

When the entire resistor 25 is shunted, the coil 10 is de-energized and the movable contact members are retained in their respective closed positions by the corresponding springs 8. The coil 16 maintains its armature 17 in its lower position to retain the rod 19 in its retracted position out of engagement with the movable switch members.

To stop the motor, the master switch is actuated to the left to open the circuits of the several actuating coils of the accelerating switches and the coil 36 of the line switch 37. The interlock 38 opens the circuit of coil 16 of the relay, and the spring 18 actuates the armature member 17 and the rod 19 to their respective initial positions to etl'ect the opening of the relays 3, 4, and 6. The system is then in readiness tor the succeeding starting operation.

A system, similar to that of Fig. except that it is arranged for use in connection with alternating current, is illustrated in Fig. o. Like numerals are employed to designate parts corresponding to those of the previous figures. An alternating-curler]t motor, having primary windings t2 and secondary windings 43, is supplied with energy through line conductors 44, 45 and 46. The primary circuit is controlled by a blllQQ-ptlle line switch 47 having an actuating coil 48.

The secondary circuits of the motor include sectional resistors 49 that are controlled by double- pole switches 50, 51, 52 and 53 having actuating coils 5st, 55, 56 and 57, respectively.

The coil 1c of the relay 2 is connected across two of the line conductors and it is. accordingly, energized in acm'u'dance with the value of the line voltage that is impressed upon the primary circuits of the motor. The coil is connected across two terminals of the secondary winding and it is, therefore, cngergized in accordance with the values of the currents traversing the secondary circuits as measured by the dil'l' erence in potential across two of the resistors 49. lvhcn the resistors are shunted, the coil in is energized in accordance with the valve of the second ary voltage.

The master switch 3;), when actuated to the right. to its second position, etlects the closing of line switch 47 to complete the primary circuit of the motor. The master switch may be actuated, by a continuous movement, to its final operative position. The closing of the primary circuit effects the energization of coil 16, since the latter is connected across two of the line conductors.

The relay i'nechanism then operates, in the manner described above in connection with the system of Fig. 5, to ctl'ect the closing of switches 54, .55, 56 and 57 in the order named. The motor is thus automatically accelerated to normal speed by the removal of the resistors 4-9 from its secondary circuit, the operation of the relay contact members being controlled in accordance with the values of the currents traversing the second ary circuits of the motor subsequent to the closing of each of the accelerating switches.

\Vhen the master switch is returned to its oil position, the resistors 49 are again inserted in the secondary circuit of the motor, and the line switch 47 opens the primary circuits of the motor. The coil 16 is (lo-energized and the spring 18 effects the opening of the several switch members.

If, during the operation of the motor, an overload occurs, the values of the currents traversing the secondary circuits of the motor are correspondingly increased by reason of the increased slip, as is well known. The coil 10 is energized in accordance with the values of the currents in the secondary circuits and, in case the overload is sufficiently heavy, certain or all of the relays 4, 5 and (i are opened to insert the corresponding sections of the resistors 49 in circuit.

\Vhen the overload decreases to such degree that the coil 10 permits the closing of such relays as may have been opened, the latter operate in sequence. as described above, to shunt the resistors 49 and thus restore normal operating conditions. The relay mechanism thus operates as an automatic safety device for protecting the motor when overload conditions obtain without interrupting its operation.

lt'. while the motor is operated at full speed in one direction. the connections are reversed by any suitable reversing switch (not shown). that is. the motor is plugged, the relay mechanism 13 operates in the manner described above in connection with over load conditions to open the circuits of the seieral actuating coils of the accelerating switches and thus effect the insertion of the resistors 49 in the secondary circuits of the motor. ("onditions correspomling to overload conditions obtain until the motor speed passes through zero value when initial or starting conditions obtain. The relays then operate in the same sequence and in accordance with the same controlling factors that govern its action during starting to effect the acceleration of the motor to full speed in the new direction.

By means of the relay mechanism. which has been described in detail with regard to its structure and with respect to its operation in conjunction with the systems to be used in connection with it, an electric motor may be automatically accelerated smoothly and gradually and without loss of time by reason ot the automatic closing ot the ac celerating switches at the instant that the proper circuit conditions Obtain. The relay mechanism is entirely automatic in its operation to permit the closing of the accelerating s itches only when the circuit of the motor has been conu'iletcd.

It will be noted further that motors may be ac elerated entirety antomaticaliy or at any rate de ired in accordance with the actuation of the master switch. The quick actuation ot' the master controller to its final operative po ition transfers the control of the accelerating switches to the automatic action of the reia v'. The accelerating switches c nnot. however, operate to shunt the coriesponding sections of the starting resistor until the master switch has been oper ated to partialiy complete he respective circuits of the actuating coils. The motor may be deceterated either by a relatively slow movement ot the master switch to its off position and thus gradually llir-tlt'illtl the starting resistor, or by opening:- the circuits ol' the mceicrating switches and the line switch by a reiatively quick movement of the master switch.

The relay mechanism operates automatically as a protective device to prevent damage to the motor by exce sive currents when overload onditions obtaiin when the motor operates in a single direction or when simiiar condition obtain upon the reversal of the motor when operating at full speed.

1 claim as my invention l. The combination with a plurality of movable members and separate means for biasing said members to certain positions, of an elcctromagnet coat-ting directly with said members for opposing said biasing means, a second electromagnet having a member coacting with said movable nit-tubers and actuatel by said second electromagnet. and means tor biasing said coacting member in such direction as to oppose the tirst biasing means.

The combination with a plurality of movable members and means comprising a plurality of springs for biasing said members to certain positions. of an electromagnet enacting directly with said members for opposing said biasing means, a second electromagnet having a member coacting with said movable members and actuated by said sec ond electron'iagnet, and a relatively strong spring tor biasing said coacting member to render the first biasing means ineffective.

3. The combination with a plurality of movable members and means for independently biasing said members to opposite ends i their respective paths of movement, of an elctromagnet coacting directly and separately with said members for opposing one or" the biasing means with a arying force, and an eleetromagnet coacting simultaneously with said members for opposing another bias ng means with a substantially constant force.

4. The combination with a magnctizable niz-mler and a niagnetizing coil therefor, ot' a pluralit of movable members coacting inle endently therewith, means for actuating each of said members separately when the n ""netization of said member tails to successively lower predetermined degrees and an electromagnet and a spring-controlled mcmber for controlling the operation of said members.

' The combination with a plurality of a. switch members and means comprising a plurality of springs for independently biasing said members to their respective closed positions and a relatively strong spring for biasing all of said members to their open positions. of an electromagnet for separately opposing the springs for biasing the members to closed positions with a force varying in accordance with circuit conditions between the terminals ot its magnetizing coil and a second elect romagnet which, when energized, renders said last-named spring inetlective.

In testimony whereof. I have hereunto subscribed my name this 11th day of August, 1923.

RAY E. DE CAMP.

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