US1891226A - Motor control system - Google Patents

Description

G. Fox 1,891,226

MOTOR CONTROL sYsTmi Dc. 2o, 1932.

Filed March 28, 1926 2 Sheets-Sheet 1 Dec. 2U, 1932. G, FOX 1,891,226

MOTOR coNTRoLsYsTEM Filed March 26. 1926 2 Sheets-Sheet 2 .SHUNTF/ELD CNTHCTOS SLUW DOWN L/M/ sw/Tchl Patented Dec. 20, 1932 UNITED lSTATES 'PATENT' oFFlcE GORDON FOX, F CHICAGO, ILLINOIS, ASSIGNOR TO FREYN ENGINEERING COMPANY,

' 0F CHICAGO, ILLINOIS, A CORPORATION OF MAINE MOTOR CONTROL SYSTEM Application flled March 26, 1926. Serial No. 97,811.

The present invention relates to electric hoists.

The present invention is particularly applicable to blast furnace operation and constitutes a carrying forward of the invention described and claimed in application Serial No. 696,139, filed March 1, 1924, by the present applicant. The present application is a continuation as to common subject matter of the prior application aforesaid. As mentioned 1n said prior application, blast furnaces are ordinarily provided with one or more bells at the top thereof, which are opened for the purpose of loading a charge into the blast furnace. Said bell or bells should be in closed position at times when the loading operation is not being performed. l

An obj ect of the present invention is to provide an improved electric bell hoist which will be more positive in operation than has been the case with prior installations.

A further object is to provide an improvement over the structure shown in applicants prior application above referred to in which improvement the speed of the movements of the bell hoist may be controlled with nicety and in which the Vperiod of time permitted for dumping may be controlled.

A further object is to provide an improved bell hoist which will use to advantage the dynamic braking features of a dynamo electric machine and which will operate with safety under all conditions likely to ber encountered in service.

A further object is to provide an improved electrical control system applicable to bell hoists.

Further objects will appear as the description proceeds.

Referring to the drawings- Figure 1 is a diagrammatic illustration of an embodiment of the present invention;

Figure 2 is a schematic view of the electrical connections of the dynamo electric machine involved in the disclosure of Figure 1; and

Fig. 3 is a schematic view of the dynamo electric machine involved in the disclosure of Fig. 1.

The numeral 1 indicates a bell forming part of a blast furnace which blast furnace is indicated by the numeral 2. Only a fragment of the blast furnace 2 is shown, said fragment being sufficient, however, to illustrate the resent invention. The bell 1 is connected y means of the flexible connector 3 to one end of the lever 4, which lever is pivoted intermediate of its length, as indicated by the numeral 5. The other end of the lever 4 is provided with the flexible connector 6.

According to the embodiment of the present invention illustrated in Figure 1, the connector 6 is connected to the counterweight 7, which counterweight 7 has also connected thereto the flexible connector 8. Said flexible connector 8 is mounted upon the drum 9, to which rotative movement may be communicated by the gear 10 meshing with the pinion 11. The numeral 12 indicates a dynamo electric machine, which may drive the couplingl 13 to communicate motion to the speed changing mechanism, which is indicated as whole by the numeral 14.

The bell 1 is normally held in a sealed position by the counterweight 7 Under these conditions no current fiows in the electrical y controlling mechanism, and no current 'is applied to the motor, except to the shunt field thereof, as will be clear from the description which follows.

Referrin particularly to Figure 2, the armature of t e dynamo electric machineA 12 is indicated by the numeral 15 and the series field winding and shunt field winding of said dynamo electric machine 12 are indicated by the numeralsl 16 and 17, respectively. The numerals 18-18 indicate the two leads of an electric circuit which may be controlled by i the blades 19-19 of a double pole switch.

Connected across the leads 18-18 is a circuit including contactor A, indicated by the numeral 20, the armature 15, the series eld winding 16, the sections'21, 22 and 23 of an accelerating resistance, and-the contactor B, indicated by the numeral 24. Also connected in the circuit referred to is the overload relay coil 25. The sections 21, 22 and 23 of the accelerating resistance are adapted to be shunted out of circuit, for which purpose accelerating contactors C, D and E are provided, which are indicated by the numerals 27, 28 and 29, respectively. Connected in parallel across the circuit of the armature 15, series field winding 16 and section 21 of the accelerating resistance is a shunting circuit controlled by the normally closed contactor F, which contactor is indicated by the numeral 30. The normally closed spring contactor G, which is indicated by the numeral 31, is provided for connecting the braking resistors 32 across the circuit including armature 15, series eld winding 16 and sections 21 and 22 of the accelerating resistance.

Connected across the leads 18-18 is a circuit including the normally closed time delay relay 33, the operating coils 34 and 35 (which coils are in parallel with each other), the normally closed time delay relay 36, and the normally open start button 37 The normally closed overload relays .38-38 may be provided in the circuit immediately above described, which overload relays 384-38 are responsive to energization of the overload relay coil 25. Connected in parallel relationship with the time delay relays 33 and 36 and the coils 34 and 35 is the operating coil 39 for contactor F, which contactor F is indicated by the numeral 30. Operation of the .start button 37 connects said operating coll 39 across the leads 18--18. Arranged in parallel relationship with the start button 37 1s the slow-down limit switch 40, 'which is biased to open position. Connected in parallel relationship with the start button 37 and the slow-down limit switch 40 is the auxiliary contact 41, which moves in unison with contactor A, which contactor A is indicated by the numeral 20. Said auxiliary contactor 41 is in closed position when contactor 20 is in closed position.

Mounted in parallel relationship with the operating coil 39 for the contactor F a circuit including the stalling limit sw1tch 42, the operating coil 43 for the contactor 31, and an auxiliary contact 44, which is mounted to move in unison with contactor 20. Said auxiliary contact 44 is in closed circuit positlon when contactor 20 is in closed position. Connected across the operating coil 43 is the operating coil 45 for the accelerating relays 46, 47 and 48, which control the relay coils 46a, 47a and 48a, respectively, which coils in turn control contactors C, D and E, respectively. Also connected in parallel circuit across the operating coil 39 for the contactor F, whlch contactor is indicated by the numeral 30, is the operating coil 49 for the time delay relay 36 and the auxiliary contact 50, which moves in unison with the contactor G, which contactor G is indicated by the numeral 31. Said auxiliary contact 50 is closed when contactor G is closed.

As indicated above, the bell 1 is normally held in sealed position by the counterweight 7. In practice, a charge for the blast furnace will be loaded upon the bell l before lifting movement is communicated to the counterwelglht 7. In order to set the dynamo electric mac ine 12 in operation to lift said counterweight 7, the start' button 37 is depressed momentarily. This closes thc circuit from the positive lead 18 through he operating coils 34 and 35 of contactors A and B, indicated by the numerals 20 and 24, respectively, and through the time delay relays 33 and 36 to the negative lead 18. By reason of the energization of the coils 34 and 35, the contactors A and B, indicated by the numerals 20 and 24, respectively, are closed, connecting the dynamo electric machine 12 across the leads 18-18 as a motor, having the sections 21, 22 and 23 of the accelerating resistance in series with the armature and series field of said motor. The closing of contactor A, indicated by the numeral 20, results in the closing of the auxiliary Contact 41, which auxiliary contact is in parallel relationship with the start button 37. Said auzgiliary contact 41, therefore, provides a maintaining circuit after the operator has released the start button 37. At this time the circuit of the controlling coil 39 of contactor F is energized, causing contactor F, indicated in the drawings by the numeral 30, to open. Circuit is also completed at this time from the positive lead 18 through the stalling limit switch 42, through the operating coil 43 of contactor G, indicated by the numeral 31, through the auxiliary contact 44 and auxiliary contact 41, to the negative lead 18. The energization of the operating coil 43 causes the opening of contactor G. At this time the stalling limit' switch 42 is closed and the slow-down limit switch 40 is open. As a result of the actions recited above, the dynamo electric machine is energized as a motor to cause the turning oi the drum 9 to raise the counterweight 7. At this time the sections 21, 22 and 23 of the accelerating resistance are in series with the armature 15, and the armature shunting circuits controlled by the contactors F and G are open. Simultaneously with the above actions, a circuit is completed through the accelerating relay 45, which results in the successive energization of the coils 46a, 47a and 48a, which coils control the accelerating contactors 27, 28 and 29, respectively. Said accelerating contactors will be chosen of the time element type, which are well known to those skilled in the art. The successive energizations of the operating coils 46a, 47a and 48a will cause the successive closing of said accelerating contactors 27, 28 and 29, whereby the dynamo electric machine 12 will be connected across the leads 18-18 with no sec tions of accelerating resistance in circuit. The dynamo electric machine 12 roceeds to hoist the eounterweight 7, and the ell 1 opens .A

by gravity.

When the counterweight 7 has traveled a short distance, the slow-down limit switch will be moved to closed position, any preferred means responsive to movement of said counterweight being suitable for operating said switch 40. There is no immediate eiect from this closure. When the bell 1 reaches a substantially full open position, the stalling limit switch 42 will be opened. Opening of said stalling limit\switch 42 results in the deenergization of the operating coil 43 of contactor G, causing said contactor G to close. Opening of said stalling limit switch 42 also results in the deenergization of the operating coils 46a, 47 a and 48a, whereby the accelerating contactors 27, 28 and 29 are caused to open. At this time the dynamo electric machine 12 is connected across the line with all of the sections 21, 22 and 23 of the accelerating resistance in circuit and with the braking resistors 32 shunted across said dynamo electric machine and a portion (21 and 22) of the accelerating resistance. The values of these resistors can be so adjusted that the dynamo electric machine will practically stall, developing only suiiicient torque to hold up the counterweight. If there should be any movement, thespeed oftravel would be exceedingly slow. At this time the burden is being permitted to drop from the bell into the blast furnace.

It will be understood that the counterweight 7 will be chosen of a suflicient value to counterbalance the weight of the bell 1 plus its burden, plus' a margin to hold the bell seated or sealed even when burdened.

When contactor Gr has closed, as referred .to above, the auxiliary contact 50, which moves in unison with said contactor Gr, is also moved to closedposition, completing a circuit through the time delay relay coil 49. As noted above, the slow-down limit switch 40 was closed in the opening movement of the bell 1. After a desired time interval, the time delay relays 33 and 36 are opened, following the energization of the time delay relay coil 49. The opening of the time delay relays 33 and 36 deenergizes the coils 34 and 35, resulting in the opening of contactors A and B. The armature circuit of the dynamo electric machine is now disconnected from the leads 18--18. Contactor F is still held open inasmuch as the circuit of the operating coil 39 of said contactor F is maintained through the slow-down limit switch 40. A reversal of rotation of the armature now takes place, the armature 15 being driven by the descending counterweight 7. Movement is restrained by reason of the fact that the armature is short-circuited through thev series field winding 16 and through the sections 21 and 22 of the accelerating resistance and through the braking resistors 32. The presence of the shunt field assists in this braking effect. The descent of the counterweight results in the movement of the bell toward closed position. The descent of 'the counterweight also causes the stalling limit switch 42 to close, but there is no effect therefrom due the presence of the 'auxiliary contact 44, which is open at this time and which 1s 1n serles with the operating coil 43 of contactor G. Movement of the bell toward its sealing position causes the slow-down Alimit switch 40 to open, open-circuiting the operating coil 39 of contactor F and .permitting sald contactor F to close. The resistance of the braking circuit of the dynamo electric machine 12 is thereby decreased and the speed of movement is slowed down. When the bell 1 closes, the counterweight 7 is supported thereb and there is no further movement. All .o the control circuits are open at this time, and only the contactors F and G are closed. This completes the cycle.

Should either of s the overload relays 38-38 operate at any point of the cycle, all of the contactors would open except the contactors F and G, which are biased to closed position. In the event that the overload relays 38-38 or either of them should open, the counterweight 7 would descend from the point at which it was located when such opening occurred, said descent being restrained by the braking circuits referred to.

Should the source of power fail at any point in the cycle, a similar 'action would take place, except that there would be no shunt field on the motor. However, the series field winding 16I would maintain the braking action unassisted to a very large degree.

Though a preferred embodiment of the present invention has been described in detail, it will beclear that many modifications will occur to those skilled in the art. It is intended to cover all such modifications that fall within the scope of the appended claims.

1. In combination, weight means, a dynamo-electric machine for lifting said weight' means, a switch for controlling said dynamoelectric machine, and means responsive to said switchfor maintaining a cycle of movement of said weight means from its lowermost position to its uppermost position and back to its lowermost position, said cycle maintaining means including resistance means and a switch responsive to the position of said weight means for inserting said resistance means into circuit with said dynamoelectric machine for stalling said dynamoelectric machine, and time responsive means for reducing the energization of said motor to permit the descent of said weight means.

2. In combination, weight means, a dynasaid electric control means includin time responsive means, resistance means a apted to be connected in circuit with said dynamoelectric machine, and a switch responsive to the position of said weight means for controlling said resistance means, said time responsive means being responsive to said switch and being adapted to control the energization of said dynamo-electric machine.

3. In combination, Weight means, a dynamo-electric machine for lifting said weight means, said weight means being adapted to drive said dynamo-electric machine when said weight means moves downwardly, said dynamo-electric machine including an armature, a series field winding and a shunt field winding, accelerating resistance means for said dynamo-electric machine, a braking re# sistor for said dynamo-electric machine, and means 'including time responsive means responsive to the movement of said weight means for controlling the connection of said resistance means and said resistor to said dynamoelectrie machine.

4. In combination, Weight means, a dynamo-electric machine for lifting said weight means, said weight means being adapted to drive said dynamo-electric machine when said weight means moves downwardly, said dynamo-electric machine including an arma-4 ture, a series field winding and a shunt field winding, accelerating resistance meansy for said dynamo-electric machine, a braking resistor for said dynamo-electric machine, means responsive to the movement of said weight means for controlling the connection of said resistance means and said resistor to said dynamo-electric machine to stall said dynamo-electric machine, and time responl sive means for causing reduction in energizetion of said dynamo-electric machine to permit dropping of said weight means.

5. In combination, weight means, a winding drum for lifting said weight means and adapted to be rotated by said weight means, a dynamo-electric machine, and power transmitting means between said drum and said dynamo-electric machine, said dynamo-electric machine being provided with a braking circuit adapted to carry the current generated by said dynamo-electric machine when said dynamo-electric machine is driven by said weight means, and time responsive electric control means for automatically stalling said dynamo-electric machine to hold said Weight means at the upper region of its travel for a predetermined interval of time.

6. In combination, weight means, a winding` drum for lifting said weight means and adapted to be rotated by said weight means, l

a dynamo-electric machine. and power transmitting means between said drum and said dynamo-electric machine, said dynamo-electric machine being provided with a braking circuit adapted to carry the current generated Vadapted to be rotated by said weight means,

a dynamo-electric machine and power transmitting means between said drum and said dynamo-electric machine, said d amo-electric machine being provided wit a brakin circuit adapted to carry the current generated by said dynamo-electric machine when said dynamo-electric machine is driven by said weight means, stalling means for automatically causing said dynamo-electric machine to hold said weight means at the upper region of its travel, time responsive means for reducing the energization of said dynamo-electric machine to permit the dropping of said weight means, and an electric control circuit for said dynamo-electric machine for varying the resistance of said braking circuit as said weight means approaches the limit of its downward movement. I

8. In combination, weight means, unitary means for lifting said weight means and for insuring that said weight means will move to a predetermined position in a safe manner whenever moved therefrom, said unitary means comprising an electric motor, and control means for said motor, said control means including stalling resistance means and a time responsive element for reducing the ener 'zation of said motor to permit said weig t means to descend. l

9. In combination, wei ht means, an electric motor for lifting saidgweight means and electric control means for inaugurating and maintaining a single cycle of movement for lifting said Weight means and returning same to its original position, said electric control means including switch-controlled means for stalling said motor for causing said motor to hold said weight means when said weight means is at the upper limit of its movement and time responsive means controlling said stalling means.

10. In combination, weight means, unitary means for lifting said weight means and for insuring that said weight means will move to a predetermined position in a safe manner whenever moved therefrom, said unitary means comprising an electric motor and a dynamic braking circuit for said motor, said dynamic braking circuit including a switchcontrolled stalling means for causing said motor to hold said weight means at the upper region of its movement for a predetermined period of time, and time-controlled means for controlling said stalling means.

11. In combination, Weight means, an electric motor for lifting said Weight means and electric control means for inaugurating and maintaining a single cycle of movement for lifting said Weight means and returning same to its original position, said electric control means including a switch-controlled resistor for carrying braking current set up by rotation of the rotor of said motor, and switchcontrolled stallin means for holding said Weight means at t e upper limit of its movement, and time responsive means for controlling said stalling means.

Signed at Chicago, Illinois, this 18th day of March, 1926.

GORDON FOX.

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