US2978219A - Stove system for blast furnaces - Google Patents

Description

April 1961 c. G.'BIGELOW ETAL 2,978,219

STOVE SYSTEM FOR BLAST FURNACES Filed June 27, -1958 5 Sheets-Sheet 1 CONTROL.

SYS T50) J5F"- CAM c 1 5316 53mg -75 OT J s 621i SPEED EEDUCER I MSCHAN ICAL LINKAGE g .1. J

I JJ I BLAST FUJZHACL 10 srove MAIN INVENTORS CHARLES G. BIGELOW, HENOLD J. Kr9267Z/V, BY 9)? 77102 \J. wflrrcarvs.

April 1961 c. G. BIGELOW ETAL 2,978,219

STOVE SYSTEM FOR BLAST FURNACES Filed June 27, 1958 5 Sheets-Sheet 2 .107 PC 1115+- 1Z Q .10 4 3 I l 124 I J7 101 J L I wbnw 405 K 425' i I I I I I 12ei .152 7 J51 5 70?! .118 .106 1 fi an": e 7- 70.4?1/5/77' CLOSED April 4, 1961 c. G. BlGELOW ETAL STOVE SYSTEM FOR BLAST FURNACES 5 Sheets-Sheet 4 Filed June 27, 1958 INVENTRS their QTTOJP April 4, 1961 c. G. BIGELOW EI'AL 2,978,219

STOVE SYSTEM FOR BLAST FURNACES Filed June 27, 1958 5 Sheets-Sheet 5 um :05 c'a'ldg snouoanamg so INVENTORS. CHQELES a. aIcELowT fiR/YOLD J. Kazs-ns/v, QRTHUR J. CIf/VIT'COMB United States Patent STOVE SYSTEM FOR BLAST FURNACES Charles G. Bigelow, Arthur J. Whitcomb, and Arnold J.

Karsten, Pittsburgh, Pa., assignors to Koppers Company Inc., a corporation of Delaware Filed June 27, 1958, Ser. No. 744,952

16 Claims. (Cl. 251- 81) off, gas burner shut-off, blow-off, mixer selector, and

chimney valves. The operation of these valves controls the inflow of gas and the outflow of flue gas to heat the stoves and the inflow and outflow of the air blast through the stoves to the blast furnace. weight of these valves, each valve is actuated by aseparate power driving means such as an electrical motor. The valves are individually operated in accordance with the demands of the stove system and blast furnace. In some blast furnace installations there may be provided a central control station which is operative to selectively control the energization and de-energization of each of the valve motor actuators so as to control the movement of the valves.

In these prior hot stove systems difficulties have been encountered in achieving trouble-free operation. These difliculties have been caused primarily by the failure of the valves to function properly. These malfunctions can be traced to overload or overtravel of the motor or valve. For example, overloading often times occurs when the movable element of the valve is jammed within the valve body because of the presence of foreign material or a tight stuffing box or because the valve gate or disc comes against a mechanical stop at the end of Because of the size and valve travel in the closed position in order to assure tight closure of the valve. Under these conditions, when valve member jars to a sudden stop at its limit of movement causing excessive stresses which often result in damage to either the valve or motor drive mechanism.

It is an object of the present invention to provide a blast furnace stove system with an improved valve operating means.

alt is a further object to provide an improved stove valve actuating arrangement incorporating therein a means for disconnecting the valve driving means from the motor in the event loads exceeding the stalling torque of the motor are encountered as in opening or closing the valve.

It is still another object to provide an improved stove 2,978,219 Patented Apr. 4, 1961 trol circuit for starting and stopping the motor to move the valve from one position to another.

It is another object to provide an improved stove valve actuating arrangement including a two-speed motor and an improved control circuit for operating the same.

A feature of the invention is the provision in the valve control circuit of a time delay circuit which is effective for a predetermined interval of time after the valve member has reached its limit of travel so as to ensure a positive opening or closing of the valve.

Generally, the invention is accomplished by providing each of the valves of a blast furnace stove system with an actuating mechanism comprising an electric motor which is mechanically coupled to the valve by the means of a fluid coupling, speed reducer, and a mechanical linkage. To control the energization of the motor there is provided an electrical control system.

Further objects and features will hereinafter appear.

Fig. 1 is a schematic representation of a blast furnace stove valve and an arrangement embodying the invention for actuating the valve.

1 Fig. 2 is a schematic wiring diagram of a control cir- (hit for operating a single-speed motor used to drive the valve members. Y

Fig. 3a is a schematic wiring diagram of a circuit for operating a two-speed motor used to drive the valve member. a

.Fig. 3b is a schematic wiring diagram of the control circuit for operating the two-speed motor of Fig. 3a.

.Fig. 4 is a graph illustrating the torque characteristics of, the motor and the fluid coupling at various speeds.

Referring now to Fig. 1, there is schematically illustrated a stove main of a blast furnace stove system embodying the present invention. 'Thenumerial 11 designates a valve, such as hot blast, cold blast, gas shut-01f, gas burner shut-off, blow-01f, mixer selector, or chimney valve, located in the main 10 between the inlet end 11a and outlet end 12 thereof to control the passage of air or gas therethrough. The valve .11-is operated in accordance with the demands of the stove and blast furnace and includes a valve member 13 movably mounted to travel a predetermined distance t between a closed position 0, in which position it is seated Within a valve seat 14, to an open position 0 in which position the air or gas flows through the port '15. The valve members 13 used in the blast furnace stove systems each generally weigh from 500 to 2000 pounds and a considerable force must be applied to move the valve member between its open and closed positions. In most cases, a

counterweight (not shown) is connected to the valve.

member 11 in such a way as to counterbalance the weight of the valve member and make it operate easier.

To actuate the valve 13 between its open and closed positions 0 and 0, there is connected thereto an actuating mechanism generally designated by the numeral 16. The actuating mechanism comprises an electric motor 17 connected by a motor driven shaft 18 to the input side 19 a of a fluid coupling 20 of which the output side 21 is convalve actuating arrangement including an improved connected to the driving shaft 21-a of a speed reduction unit 22 having an output shaft 23 connected to a mechanical linkage 24 which is operatively connected to the valve member 13. I I

The mechanical linkage 24 is usually of the type which imparts-a mechanical advantage for moving the valve member 13, such as for example by a crank, gear and pinion, or a pulley arrangement. The type of mechanical linkage used may vary in accordance with the structural characteristics of the valve. For example, in a hot blast valve it is preferred to use a cable and pulley arrangement, while in a gas burner shut-off valve, it is preferred to use ,a gear and pinion drive. It is to be understood, of course, that in the event the characteristics of the valve are such that a mechanical linkage is not required, it may be omitted and the output shaft 23 may be connected directly tothe valve member 13.

Mechanically connectedto' and ,driven by the speed reducer 22 is thecam type limit. switch 154 in which there are cam switches later described in Fig, 2' as156 and 176 and in Fig. 3b as 280, 28 2, 284-a, and 286", which are usedin conjunction with the control system 10010 govern the speed and stopping of the valve member 13. i

Connected to the input shaft 21-aof the gear reduction unit 22 by way of the shaft 21-a is the output end 21 of the fluid coupling 20 of which the other end 19 is con-' nected to the driving shaft 18of the motor 17'. The

. fluid'coupling may be similar to the typemanufactured by the Twin Disc Clutch Conipanyof Rockford, Illinois.

The fluid coupling 20 is selected of such a size that it counter clockwise deeenergi'zation of the'clockwise solenoi'dr112 of 'contactor R0, the armatures 113, 115, and 117' move outo'f contact with their respective contacts 114, 116, and 118 so as to de-energ'ize the motor.

Ener-gization of the counter clockwise solenoid 120,

- whichis a part of contactor RC, causes three armatures 121, 123, and 125 to move downwardly to engage the will transmit less than the pull-out or stalling torque of the motor 17 when running at a motor speed approximately the speed at which the motor stalling torque occurs. This relationship is shown in Fig.4 wherein the curve a represents the percentagesof torque transr nitted by the fluid coupling at various percentages of synchronous speed of the motor and the curve b represents the percentages of torque developed by the motor. Preferably this coupling size is such that the fluid coupling will be unable to transmit full motor torque until the speed of the driver end of the coupling is approximately 65% of the synchronous speed of the motor. Below65% of the synchronous speed of the motor should the valve become jammed, the slip will be at 100% and the coupling Normally as the speed of the motor '17 and the disc 19 in I will be transmitting less than full motor torque.

creases, the starting torque exerted on the member 21 correspondingly increases untilthe'motor and member 21 reach relative speedsiat which the torque-required to drive the load is, developed. During this time the slip increases and the torque applied on the valve member 13 correspondingly increases. This assures a shockless and cushioned start of the valve driving mechanism. I

In the event that there is excessive load frornstuffing box :friction, or the valve disc 13 reaches a mechanical stop at the end of valve travel, the torque required to move the valve disc 13 will exceed the pull-out or stalling torque of the motor with the result that the motor speed and the fluid coupling speed will be decreased and as a contacts 122, 124, and 126, respectively, thereby connecting the lead 107 to lead 105 byway of leads 127 and 128, the lead 108 to lead 104 by way of leads 129 and 130, and the lead 109 to lead 106'by way of leads 131 and 132. In this manner, the phases of the power supply to the motor'are reversed thereby causing the motor to rotate in a counter clockwise'direction and close the valve. Upon de-ener-gization of the counter clockwise solenoid 120, the armatures 121, 123, and 125 move to the positions shown, de-energizin-g the motor 17.

The operation of the clockwise and counter clockwise directional contactors R0 and RC are controlled by a motor control system generally designated as VM.

The control system VM is energized by the secondary winding of the step-downftransformer 184 of which the 1 primary 135 is connected'to leads 108 and 109. Upon closing 'of'the master switches 136, the excitation of the second-ary'winding133 causes the terminals 137 and 138 ,to become energized. Connected in parallel to-terrninals 137 and '138 is a control circuit generally designated as and a secondcontrol circuit generally designate as VC for rotating-the motor counter clockwise to close the valve.

For rotating the motor c-lock wise and'closing the valve,

control circuit V0 is energized.

, When the selector switch 140 is in engagement with contact -1'40-a,the circuit VO will be governed by the master control system (not shown) by means of the-armature 141. When armature 141 is engaged with contact result, the torque output of the fluid coupling 20 will not of the fluid coupling 20 and thedriven end 2 1 of the coupling will be at a standstill ,while the motor 17 continues to rotate. As a result of this action, the driven end or the valve member 13 is brought'to a sudden stop which is cushioned with no shock or severe overload on the motor or the valve driving mechanism.

In carrying out the invention, either a single-speed or a two-speed motor may be used depending on the structural characteristics of the valve. For example, in the operation of a typical hotblast valve, it has been found preferable to use a two-speed motor and in a typical burner shut-ofi valve, to use a single-speed motor.

This design value must be 142, a circuit is completed toenergize clockwise solenoid 1 12 of contactor R0 from terminal 137 by way of lead 144, lead 143, contact 142, armature 141, contact 140-51,

selector switch 140, normally-closed armature 139, contact .139-a, through the solenoid 112 to terminal 138. The master control system, not shown, is usually located in a central location in the blast furnace installation and includes the electrical circuitry for controlling the opera- Referring now to Fig. 2, there is illustrated a singletion, sequencing, and interlocking of all of, the valves of the hot blast stove system.

Manual operation of the solenoid 1-12 of the directional contactor R0 is effected by-positioning the switch in engagement with the terminal 145 and depressing the push button 146-a into engagement with the contacts 147 and 146 such that it connects the lines 148 and 149. The line 148 is connected to contact 145 while the line 149 is connected to the terminal 137.

When the valve member 13 reaches its predetermined "open position 0, there is operatively associated with the motor 17,by way of the speed reduction unit 22, a cam type limit switch mechanism 154 including a shaft 75 carrying a cam 155 which is set to move the switch 156 into engagement with the contact 157 when the valve reaches its open position 0. Closing of the switch 156 connects the contact 157 to one end of the valve opening limit solenoid 161 to the terminal 137 by way of the lines '158 and 159 thereby to energize the valve opening limit solenoid 161 which is connected to the terminal 138 by way out the line 160. When the valve opening limit When the selector switch 165. is in engagement with contact 166, the circuit VC will be governed by the master control system (not shown) by means of ,the armature 167. When armature 167 is in engagement with contact '168, a circuit is completed to energize counter clockwise solenoid 120 of contactor RC from terminal 137 by way of leads 159 and 170, contact 168, armature 167, lead 169, contact 166, selector switch 7 165, lead 164, normally closed armature, 162, through the counter clockwise solenoid 120' of contactor RC through lead 120-a to terminal 138. In this connection, it is to be noted that the master control system may incorporate interlocking meansto prevent the simultaneous closing of the armatures ,141, the circuit VO, andthe armature 167 of the circuit VC. .By using such interlocking means, the contactors R and :RC cannot.

be operated at the same time. s

' Manual operation of the circuit to energize the solenoid 120 of the directional contactor RC is eltected when the selector switch 165 engages the terminal 171 and the push'button 172 is depressed into engagement with the contacts 173 and 174, thereby completing a circuit from the solenoid 120 to the terminal 137 by way of lead 159, the contact 174, the pushhutton 172, the contact 173, lead 171-a, contact 171, selector switch 165, lead 164, normally closed armature 162, contact 163, through solenoid 120, through lead 120-a to terminal 138. 1

When the valve member K13 reaches its predetermined closed position c, a cam 175 on the cam' type limit switch mechanism 154 is set to move the limit switch 176into engagement with the contact 177 thereby to connect one end of the close limit solenoid 178 of a close limit relay having a normally closed armature 1 62to terminal 137 by way of lines 159. Theother end of the close limit solenoid 178 is connected to theterminal 138 by way of the lead 178-a. Hence, when the limit switch 176 is closed, the close limit solenoid 178 is energized thereby to move the armature 162 out of engagement with the contact 163. In this manner, the circuitto the counter clockwise vsolenoid 120 of the directional contactor RC is de-energized, and its armatures 121, 123, and 125 open, and the motor 17 is de-energized. I

In Figs. 3a and 3b, there is shown a two-speed motor 17 for actuating the valve operation. While the motor 17 may be of any conventional two-speed type such as a squirrel cage induction motor having taps for varying the fields and thereby the speed in the well known manner, there is shown, for purposes of illustration, a threephase motor having Y and delta connections. The electrical motor 17 has six terminals of which terminals 201, 202, and 203 convert the motor to a delta wound motor for driving the motor at a slow speed and terminals 204, 205, and 206 convert the motor to a Y winding for a faster speed. This motor is energized from the three- phase power terminals 207, 208, and 209.

Control of the rotation and the speed is obtained by use of four contactor relays, namely directional contactors R0 and RC which determine the direction of rotation, and speed contactors MS and MF which control the motor speed.

For the purpose of operating the motor both clockwise and counter clockwise in order that the valve member may be moved from its open to closed. and from its closed to open positions, there is provided a directional relay contactor R0 and a directional relay contactor RC respectively as shown in Fig. 3. The directional 6 contactor R0 comprises a clockwise solenoid 242, which when energized, is effective .topull thearmatu'res 243 and 245 of the relay contactor R0 into engagement with the contacts 244 and 246, respectively. As a 'result, terminal 207 is connected to power lead 247 by way of lead 249, contact 244 and armature 243, while terminal 208 is connected to power lead 248 by way of lead 250, contact 246, and armature245. Connected to the terminal 209 is a power lead 251. The power leads'247, 248, and 251 are connected to a suitable source of threephase power 252. When the armatures 243 and 245 of contactor R0 are closed, the power supply circuit is set up to cause the motor 17 to rotate in a clockwise direction so as to move the valve member from its closed to open position but such action takes place only after a speed contactor has closed to determine whether the motor runs at slow speed or at fast speed. i

The directionalcontactor RC is operative to rotate the motor17" counter clockwise and does so by reversing the connections to the power supply, that is terminal 207 is connected to power lead 248 instead ofpower lead 247 as was the case for clockwise rotation. Likewise, terminal 208 is connected to power lead 247 instead of power lead 248 as was the casefor clockwise rotation. The relay contactor RC includes the counter clockwise solenoid 253, which upon excitation, causes its armatures 254 and 256 to be pulled into engagement: with the contacts 255 and 257, respectively. As a result, terminal 208 is connected to power lead 247 byway of lead 250, lead 259, contact 255, armature 254, and lead 258, while terminal 207 is connected to power lead 248 by way of lead 261, contact 257, and armature 256. "The relay. contactors MS and MF select the speedfat which the motor'is to run. The slow speed relay contactorMS comprises the slow speed solenoid 210 which actuates the armatures 211, 213, and 215. The solenoid 210 pulls the armatures 211, 213, and 215 into engagement with contacts 212, 214, and 216, respectively, thereby connecting motor lead 201 to terminal 207 by way of lead 217, contact 212, armature211, and lead 2 18and also connecting motor lead 202 to terminal 209-a by way of terminal 240, lead 219, contact 214, armature 213, and lead 220; and also connecting motor lead 203 to terminal 208 by way of lead 221, terminal 239, contact 216, armature 215, andlead221-a. Thus, upon the excitation of the solenoid 210, of speed contactor MS, and solenoid 120 of directional relay contactor R0, the motor 17' is energized from the power source 252 and operates as a delta wound motor at slow speed.

Upon energization of the fast speed solenoid 222, armatures 223, 225, 227, 229, and 231 move downwardly to engage contacts 224, 226, 228, 230, and 232, respectively. This connects terminal 206 through lead 233 and lead 234 to power terminal 209, connects terminal 204 through lead 235 and lead 236 to power terminal 207, and connects terminal 205 by lead 237 and lead 238 with power terminal 208. The engagement of armatures 225 and 227 with contacts 226 and 228 shorts terminals 239 and 240 with terminal 241 thereby destroying thedelta connection. Accordingly, this changes the delta connection to a Y connection and enables the motor to be operated at its fast speed. In the above manner, a provision is made for operating the motor at two speeds from the same power source. v i

As in the single-speed motor described above, the op eration of the two-speed motor is controlled by a control systemgenerally designated as VM. The control system VM is energized by the secondary winding 263 of a step-down transformer 264 of which the primary is connected to the power leads 247 and 248 by leads 264-0 and 264 12. Upon closing the master switches 265, the excitation from the secondary winding 263 causes the terminals 266 and 267 to becomeenergized."

Connected in parallel to terminals 266 and 267 is'a first circuit v: for controlling. the directional contactor- R0 which governs the rotation of the motor 17 in a clockwise. direction toopen the. valve-13 and: afsecondi circuit VC' for controlling the directional contactor RC which governs the rotation. of the motor 17 in a counter clockwise direction to close the valve :13. Also there isa third circuit RF for controlling the speedrelay con tactor' MF which causes. the motor to operate attest a circuit for energizing solenoid 210 of the speed con-- tactorMS thereby causing the motor 17- to. run at slow speed- The open timer relay-TO is of the well known pneu-'- matictype and comprises the solenoid 291, two normally open armatures 276 and 295, together with one normally speed,'and a fourth circuit RS-for controlling the-speed relay contactor MS which causes the motor toop'erate at slow speed. For rotating the motor 17-clockwise and closing the valve, the control circuit V0 is energized.

When the selector switch 301 is in engagement with contact 302, the circuit 'VO will be governed by the master control system (not shown) by means of the; armature 304. When the armature304 is in engagement with contact 304-a, a circuit is completed to energize opening. solenoid 2420f the relay cont-actor RO' from terminal 266 by way of armature 304, contact 304-a, contact 302, selector switch 301, lead 303, normally closedarmature 297, contact 298, lead'304, "through the solenoid 242 to terminal 267. Energization of opening sole,-

noid 242 of the directional relay'contactor R0 closesv armatures 243 and 245' of the same 'contactor and sets up the power circuit to cause the motor 17 to run clock wise as soon as one of the speed'relay contactors MF or MS is closed." a 1 Also actuated by the solenoid 242 of the directional relay contactor R0 is the armature 268, which when closed sets up a circuit for energizing the solenoid 222 of the MF speed relay contactor or 210 of the MS speed originates fromterminal 266 and terminates at terminal 272-a by way of lead 270, armature 268, contact 269, lead 272, to terminal 272-a.

Connected inparallel between terminals 9 272-11 and closed armature 274. When thesolenoid' 291 is energized, the armatures276 and 295 instantly engage contacts 277 and 296, respectively, and simultaneously the normally closed armature 274 disengages from contact 275.. When the solenoid 291 isde-energized, there is an adjustable preset time delay caused by the pneumatic action of the relay mechanism before the through arma-' tures resume their normal positions.

The cam 281 of the cam type limit switch mechanism 154 is positioned so as to move the switch 282 into engagement with the contact 282 12 at approximately the point at which the valve member Breaches its open posiand 297. i Asa result of the actions described about the switch 282 causes energization of the solenoid 295 of the open limitzrelay OR which in turn opens the. circuit through its armature'297 thereby breaking one of the relay contactor, through circuits RF or RS. This circuit 273 are two circuits RF'and RS, which are operative to.

select whether the motor 17 runs fast or slow. i The circuit RF starts from terminal 272-a andpasses successively through the normally closed arrnature274 of the open timer relay TO, through the contact 275,. through the :fast speed solenoid 222 of the speed relaycontactor MP to the terminal 273. The second circuit RS starts from terminal 272- w and passes successively through the normally open armature 276 of the open timer relay TO, the contact 277, through the slow speed solenoid 210 of the, speed relay contactor MS to terminal 273. When the clockwise armature 268 of the directional relay contactor R0 is closed, a selection is made as to whether the motor operates fast or slow depending upon whether open limit timer relay T0 is energized or de-energized so as to close the armature 274 or close the armature 276 as more fully to be explained below. I Operatively connected to the motor by way of the gear reduction unit- 22 is ashaft 75'. including a cam type limit switch mechanism 154' including four cams 279,

281, 283, and 285. Cam 279 is positioned so that when the valve13 approaches its open position 0 or slowdown switch 280 energizes the circuit tothe solenoid 29.1" of the open timer relay TO. Energization of the solenoid 291 causes the armature 274 to break its connectionwith contact 275 and interrupt the circuit to the solenoid 222 of the speed contactor MF thereby preventing the motor 17' from operating at fast speed. Simultaneous with this action is the engagement of armature 276 with contact 277 of the open timer relay TO which action completes parallel circuits feeding the solenoid 242 of the directional contactor R0. This action would de-energize the solenoid 242 except for the parallel feed from terminal 266..to the solenoid 242v by way of lead 300, contact 296, armature 295aof the open timer TO, lead 299 to the solenoid 242. Energization of solenoid 295 of the open relayORtalso opens its second normally closed armature 293. Disengagement of armature 293 from its contact 294 breaks the circuit from terminal 266 to the solenoid. 291 of the open timer relay TO. At the end of the timing period, the three armatures 295a, 274, and 276 of theopen time'r relay T0. will reverse their positions; This. changefin armature position has no effect at this time in the case of armatures 274 and 276, but the disengaging ofarmature 295a from contact 296 breaks the circuit from terminal 266 to the solenoid 242 of the directional contactor R0 by way of lead 300, contact 296,

armature 295a, tothe solenoid: 242. This action results in de-energization of the solenoid 242 and causes its three armatures 243, 245, and 268 to disengage from their respective contacts Arrnatures 243 and 245 disconnect the power supply to the motor, causing the motor to stop, while armature 268 breaks the power supply to the solenoid 210 of the speed relay contactor MS causing it to supply after a preselected time interval.

spective contacts.

The net result of the foregoing is as follows: the motor is caused to rotate in a clockwise direction at fast speed to open the valve. .When the valve approaches the open position or slowdown point, the camswitch causes the disengage its armatures 211, 213, and 215 from their re .motor torun at slow speed. Just before valve reaches the full open position near final stop, another cam switch de-energizes the open timer relay T0 with the result that the motor willbe disconnected from the power Meanwhile, the valve member reaches the full open position and is against a mechanical stop preventing further movement. As a result, the fluid coupling is overloaded and slips leaving the driven end'at a standstill while the motor continues to run at slow speed.

Automaticoperationof the circuit VM is effected whenthe selector switch 301 is in engagement with the terminal 302 and the armature 304 engages the contact 304a thereby to connect the lead 303 to the terminal 266 by Way of the lead 270. Actuation of the armature 304 to its closed position is accomplished by way of the operation of the master control system as, explained hereto- 9 fore in connection with the single speed motor. Connected to the line 303 is the'armature 297 of the open relay OR which remains in engagement with the contact 298 during the fast speed operation of the motor and in this position is eflective to complete the circuit and energize the solenoid 242 of the directional contactor R which is connected thereto by way of the lead 304.

1 Manual operation of the opening of the valve member 13 is accomplished when the selector switch 301 engages the terminal 307 and the manual push button 308 is depressed so as to bridge the leads 309 and 310 of which the lead 310 is connected to the terminal 266 by way of the line 278. I

. The control circuit VC' for closing the valve is similar to the control circuit V0 for opening the valve and includes the solenoid 253 of thedirectional relay contactor RC which when energized as explained above is operative to move the armatures 254 and 256 to engage the contacts 255 and 257 respectively andthereby cause the motor to rotate counter clockwise when-one of the speed contactors MF or MS is energized. The solenoid 253 of directional contactor RC also causes the armature 310 to engage the contact 311 and thereby set up a circuit RF to the solenoid 2220f the fast speed relay contactor MF or a circuit RS for the slow speed relay contactor MS, depending upon the selection made by the close timer relay TC. Since the solenoid 329 of the close timer relay TC is not energized, the normally closed armature 315 on this timer will be closed against its contact 316 and the circuit will be completed from terminal 266 to the solenoid 222 of the fast speed contactor MFby way of lead 278, lead 313, armature 310, contact 311, lead 312, terminal 314, armature 315, contact 316, lead 317 to the solenoid 222 of the fast speed contactor MF.

In starting the closing movement of the valve member 13, the control system is energized so as to operate the motor at fast speed until the valve member 13 reaches the slowdown point as it approaches the closed position c. At this time, the cam'283 of the cam typelimit switch mechanism 154 is set 'to move the switch 284q into engagement with the contact 284 so as toconnect the terminal 266 to the solenoid 329 of the close timer relay TC by way of the lines 278 and 323, armature 284a, contact 284, normally closed armature 320, and contact 321. Hence, when the cam switch 284 is closed, the solenoid 329 of the close timer relay TC is energized. The close timer relay TC has two normally open armatures 326 and 317 which engage contacts 327 and 318, respectively, when the solenoid 329 is energized. In addition, this timer relay TC has a normally closed armature 315, which disengages from contact 316 when the solenoid 329 is energized. All of these armatures tion 0, the cam 285 of the'cam type limit switch 154,

causes the switch 286 to engage with its contact 286-a 321 of the close limit relay CR breaks the circuit to the move instantly when the solenoid is energized but there is an adjustable prmet time delay before these armatures move in the opposite direction after de-energization of the solenoid 329 due to the pneumatic bellows action of the timer mechanism.

Energization of the solenoid 329 of the close timer relay TC, caused its normally closed armature 315 to be disengaged from its contact 316, breaking the circuit RF through the solenoid 222 of the fast speed contactor MF thereby discontinuing the fast speed operation of the motor. [At the same time, the armature 317, of the lowing paragraph.

When the valve member 13 approaches the closed posisolenoid 329 of the close timer relay TC. As a result of the action of the pneumatic bellows in this timer, the functioning of the armatures 315, 317, and 326 of this close timer relay TC is delayed for a preset time. This permits the motor town at slow speed driving the valve 13 to final stop in the closed position' At this valve position, the torque required to move the valve member is'too great for the fluid coupling to transmit with the result that there is slipin the'fluid coupling thereby permitting the motor and the driven end of the fluid coupling to run atslow speed while thedriven end of the coupling and the ,valve member are at a standstill. The torque relationship of the motor operating at slow speed and the torque characteristics of the fluid coupling are represented by the curves d and a, respectively, in Fig. 4.

At the end of the preset time interval, the three armatures 315, 317, and 326 reposition themselves. Armature'317 disengages from its contact 318 on the close timer relay TC, thereby breaking the circuit RS to the solenoid 210 of the slow speed contactor MS, while at the same time, armature 326 disengaged from its contact 327, thereby breaking the circuit to the solenoid 253 of the directional contactor RC, thereby de-energizing and stopping the motor 17. i I Y Automatic operation of the circuit VC' is effected when the selector switch 334 is engaged with the terminal 335, and the armature 336, under the control of the master control system, engages the contact 337 such that when thearmature 331 of the close relay OR is in its normal position of engagement with the contact 332, the circuit to the solenoid 253 of the directional contactor RC is completed to the terminal 266 by way of the lines 313 and 278. In connection with the armature 336, it is to be observed that interlocking means may be provided in the master control system between the armature 336 in the circuit VCand the armature 304 in the circuit V0 811C111 that both the circuits are not energized simultaneous y.

Manual energization of the circuit VC' for closing the valve member 13 is accomplished when the selector switch 334 engages the terminal'338 and the manual push button 340 is depressed so as to bridge the lines 341 and 311a, the latter being connected to the terminal 266 by way of line 278. l

Since the motor is not stopped instantly when the valve reaches the closed position, there is a decided advantage in having the motor run at reduced or slow speed when the valve reaches the closed or 0 position because there will be less shock and jar to the valve member as well as the driving mechanism. Such action is obtained through the use of a two-speed'motor, because the-fast speed can be used to obtain fast operation of the valve, while a change to slow speed at the slowdown point slightly ahead of the final stop will give the result that the motor will be running at slow speed when the valve reaches final stop. Because it is running at slow speed, the fluid coupling transmits far less torque to the valve driving mechanism with the result that when the valve member stops abruptly in the closed position, the fluid coupling is unable to transmit sufficient torque resulting in 100% slip in the fluid coupling and a CllSh! ionedstoppage of the valve'member while the motor continues to. run.

In closing a valve and in some cases. in opening a valve,

the valve member comes against a positive metallic stop with the result that the valve member or disc is 'forced 12 for controlling said motor at said first operating speed during aportion of the said valve member movement and means to de-energize such said first control system and energize a second control system a selected distance from said openor closed position of said valve member thereby 'to operate. said motor at said second speed a during the. latter movement, of said valve member.

resultin incomplete valve travel andvalve leakage. The time delay circuit described above for maintaining the motor operation after the valve member 1 3 has reached its limit of travel is advantageous since it forces seating of the valve at either end of travel and. permits the final making its adjustment easy and simple. Variations and modifications may be made may be used without others.

What is claimed is: g l. A blast vfurnace stove system comprising -a gaseous fluid conducting main having an inlet and an outlet end; a valve mounted in said main for controlling the flow of gaseous fluid through said inlet and outlet end, said valve comprising a valve seat and a valve member movable between closed posit-ion preventing the flow of said fluid through said main, an open position permitting the flow of said fluid through said main; actuating means for moving said valve between said open and closed positions, said actuating means including an electrical motor and a fluid coupling. operatively connecting said motor with said valve member, said fluid coupling having a torque output less than the stalling torque of said motor at motor speeds equal to and lessthan the speed at which the motor stalling torque occurs.

2. The invention as defined in claim 1 including a control system having means for causing said motor to rotate in a direction to move said valve member to said open position and also for causing said motor to rotate in a direction to move said valve to said closed position. 3. The invention as defined mclaim 2- in which said I control system includes limit means for die-energizing said motor when'said valve member reaches said open or closed positions. i a

6. The invention. as defined in claim 5 in which said control system and said limit means include relay means responsive to electric energy and operative to positively interrupt the supply of electrical energy to said motor. .7. The invention as defined in claim 1 in whichgsaid within the scope of the claims and portions of the improvements the supply of 9. The invention as defined in claim 7 in which said control system includes control means for causing said motor to rotate in a direction to move said valve member to said open position and also for causing said motor to rotate in a direction to move said valve to said closed position.

10. The invention as defined in claim 9 in which said controlmeansincludes means rfor energizing a first control system for controlling said motor at said first operating speed during a portion of the valve member movement from one position 'to another, and means to deenergize said first control system and energize a second control system a. selected distance from the final limit of travel of said valve member thereby to operate motor at second speed during another portion of the movement of said valvemember. i

11. The invention as defined in claim 10 in which said control system includes limit means for de-energizing said motor when. said valve member reaches said open or closed positions.

12. The invention as defined in claim 8 in which said control system includes a preset limit means for initiating the change fro-m said first operating speed to said second operating speed at a predetermined distance from said open or closed position, and a second preset limit means for de-energizing said motor when said valve member reaches said open or closed position.

13. The invention as defined in claim 10 in which said control system. includes. a first preset limit means for initiating the change from said first operating speed to said second-operating speed at a predetermined distance from said open or closed positions, and a second preset limit means for de-energizing said motor when said valve member reaches said open or closed position.

14. The invention as defined in claim 10 in which said control system includes time delay means for maintaining said motor energized for a selected time after said limit means are normally effective to de-energize said motorwhen said valve member reaches said open or motor is a two-speed motor having a first operating speed closed positions.

15. The invention as defined in claim 13 in which said control means and said limit means includes a relay means responsive to electrical energy operative to positively interrupt the supply of electrical energy to said motor;

16 The invention as defined in claim 13 in which the control system includes a time delay means for maintalnmg said motor energizedior a selected time after i said limit means are normally effective to de-energize said motor when said valve member reaches said open or closed positions.

' References Cited in the file of this patent Q UNITED STATES PATENTS 1,339,044 Sears May 4, 1920 1,908,763 Kelty May 16, 1933 2,342,414 'Magill Feb. 22, 1944 2,598,062 Krecan May 27, 1952 2,629,264 Kron Feb. 24, 1953

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