US1483064A - Motor-controlling device - Google Patents

Description

Feb. 12 1924. 1,483,064

Bf S. AIKMAN l MOTOR CONTROLLING DEVICE Filed Oct. 14 1919 2 Sheets-Sheet l ATTORNEY B. s. AIKMAN MOTOR CONTROLLING DEVICE Feb. 12 1924. 1,483,064

Filed oct. 14. 1919 2 sheets-sheet 2 INVENTOR BurgrYQn S. Ai kmem ATTORNEY Patented Feb. 12, 1924.

UNITED STATES P 1,483,064 ATENT ori-Ical BURTON S. AIKMAN, OF MILWAUKEE, WISCONSINLASYSIGNOR TO NATIONAL BRAKE ELECTRIC COMPANY, OF MILWAUKEE, WISCONSIN, A CORPORATION OE WISCONSIN.

MOTOR-CONTROLLING DEVICE.

Y Application led October 14, 1919. Serial No. 330,601.

To all 'whom t may concem:

, Be it known that I, BURTON S. AIKMAN, a citizen of the United States, residing at Milwaukee, in the county of Milwaukee and State of Wisconsin, have invented new and useful Improvements in Motor-Controlling Devices, of whichthe following is a speciication.

This invention relates to electric motor controlling devices, and more particularly to a controlling device fora motor. employedI to operate an air compressor.

The principal object'of my invention is to provide an improved motor controlling device of the above character.

In the accompanying drawings; Fig. 1 is a central sectional view of a motor. controlling device embodying my improve-v ments, and showing the parts in the switch open position; Fig. 2 a view similar to Fig. 1, showing the parts in positionwith the switch closed and the resistance short-circuited; Fig. 3 a view'of a portion o fthe mechanism shown in Fig. 1, showing the switch closed and operatlng through a re.v sistance; Fig. 4 an elevational view of the motor controlling device; Fig. 5 a wiring diagram, showing the circuit connections in the open position of the switch; Fig.v 6 a wiring diagram, showing the circuit connections with the switch closed and operat ing through a resistance; and Fig. 7 a wir-4 ing diagram, showing v'the switch closed with the resistance short-circuited.

As shown inthe drawings, the apparatus comprise a motor controlling Adevice mag' 1, avingla chamber 2 connected to a cyl-` inder 3 containing a' piston 4 for operating, `through a stem 5, a suction valve 6 'of a fiuid compressor.

The casing of the motor controlling de vvice 1 has a piston chamber 7, containing a piston 8 and provided with aV piston -stem 9. Pivotally mounted on the casing of the motor controlling device and arranged on opposite sides of` the piston stem 9 are two main switch arms 10, each having al contact 11 adapted to first engage a corresponding yielding contact 12 and then a corresponding fixed contact 13. Each main switch arm is pivotally connected to an auxiliary switch arm '14, which is also pivoted to the controller casing and has a common depending latch mem r 15 pivoted thereto. v

The switch arms 10 and 14 are pivotally connected to the piston stem 9 at opposite sides by means of floating pins 16, adapted l to work in slots 17 and 18 of the respective switch arms 1() and 14 and a slot 19 in the piston stem 9. A coil spring 20 mounted in pockets provided in the switch arms 10 y and 14 tends tol ieldingl1 hold said arms apart, as s own in ig. 2. Mounted on the controller casing are two magnet coils 21, each havin a pivotally mounted armature 22 provi ed with a projection f23'` adapted to y Mounted centrally from said chamber to a fluid sup ly asl* sage 32, controlled by the dou le at va ve 26.

Secured to the motor controller casing is a pumpv governor 39 of any desired construction and ,shown in the drawings as comprising a movable diaphragm 33, subject on one side to the pressure in the usual storage reservoir into which the com ressor or pum4 compresses fluid, said fiui being supplie thereto through pipe 34 and passage 35, and on the oppositeside to the pressurefof an adjustable spring 36. The movement of the diaphragm 33 is adapted tobe transmitted to an arm 37 for operat- 'ing a movable .contact 38, which controls Where the construction is designed for controlling a resistance in two legs of the primar circuit, there is provided a switch controlling-mechanism for the resistance in each leg, as hereinbefore described and as shown in the wiring diagrams; Figs. to 7 inclusive.

A manually operated lever 40 is provided which is adapted to operate a n er 41 and the piston stem 9 is provided wit' a pin 42 adapted to be engaged by lthe finger 41 and in operation, when there is little or no fluid.

lpressure in the storage reservoir and it is desired to start the compressor, the handle 40 is moved to its full upward position, as shown in Fig. 3 of the drawings. This movement causes the linger to vengage pin 42 and lift the piston stem 9. The main and auxiliary switch arms 10 and 14 are then lifted through the floating pins 16, so that the contacts 11 engage the yielding contacts 12, but not suiciently-to engage the fixed contacts 13, as shown in wiring diagram, Fig. 6. resistance element 43 is then connected into two legs of the primary circuit of the motor. K

Since there is little or no pressure in the reservoir, the pump governor 39 will operate so 'that contact 38 will close a shunt circuit through the coil 24 causing armature 25 to move to its closed position.

@ne switch arm i0 then connects one resistance element 43 through the corresponding magnet coil 21 with one leg of the primary circuit of the motor, while the other switch arm connects another resistance elevment 43 through the corresponding magnet coil 21 with another leg of the primary circuit, as shown in the wiring diagrams.

22 to move forward, so that the projections 23 of the armatures 22 engage they latch 15, moving the same forward, so that the latch :will be tripped from engagement with the locking member 44 of the armature 25.

The lever 40 must be manually held in its full upward `position until the motor has" reached a speed such that the current flow .in the coils 21 will be insuicient to hold the armatures 22 in closed'position. The armatures 22 will then drop back by gravity, permitting the latch to resume its normal vertical position. The lever 40 may now be released, allowing the latch 15 to engage the locking member' 44. The latch 15 and the auxiliary switch arms 14 will thus be prevented from moving downwardly by the locking member 44, while piston 8 willbe permittedv to move downwardly to the action of thespring 49.

The auxiliary arms 14 being now held in position by latch 15, the downward movement of piston 8 moves the main switch arms 10, compressing the springs 20, so that the contacts 12 will be pressed upwardly,

lto be moved permittin the contacts 11 to engage the contacts 13, t us short-circuiting the resistance 43 in each leg of the circuit, as shown 1n Figs. 1 and 7.

l'n this position of the parts, the magnet coil 24'. being in a shunt circuit with the motor, is energized, so that armature 25 is held in its closed position in which the stem 27 operates the double beat valve 26 to close communication from the storage reservoir pipe 34 to chamber 2, and open communication from said chamber through passage 45 to passage 32 and thence to the atmosphere through a port 46 in the valve 30.

rhe compressor is now operated by the motor to compress fluid into the storage reservoir, and when the pressure "in said reservoir has been increased to a predetermined degree, the diaphragm 33 of the pump governor 39 is operated by reservoir pressure to throw the switch contact 38, so as to open' the shunt circuit containing coil 2A, so that said coil is deenergzed, a1- lowing armature 25 to move outwardly, so as to cause the. latch 15 to be tripped from its engagement with the lockmg memher 44.

This will permit the auxiliary arms 14 and the associated parts to dro down rapidly due to the pressure exerte by the spring 49, thus causing the movement of the contacts 11 to open the motor circuit and thus stop the pump.

When thc armature 25 moves away from the magnet 24, the stem 27 will be free to move, permitting the double beat valve 26 by reservoir pressure so that communication is opened from the reservoir pipe 34 to passage 45, permitting the chamher 2 to be charged with fluid at reservoir pressure and causing thev piston 4 to be operated so as to open the inlet valve 6 of thecompressor t-hrou h the stem 5, thus rendering the inlet valzve of the compressor ineffective.

1vWhen the pressure in the storage reservoir has fallen to a 7iredetermined degree, the pump governor diaphragm 33 will be operated tol permit the spring 36 to shift the contact 38 to its closed position, thus closing the shunt circuit through the coil 24. The armature 25 will then be movedl toward the coil 24. cousin the stem 27 to operate the double beat va ve 26, so as to cut of the' reservoir supply passage and connect passage with the passage 32.

.Since at this time, the chamber 2 contains fluid at reservoir pressure, uid from said chamber will flow to valve 30,y forcing same i to its outer osition, in which communication is opene so the Huid can ow from the chamber 2 to the piston chamber 7. Piston 8 is thereupon moved to its extreme upper position, causing the switch arms 10 to be moved so that the contacts 11 engage the contacts 12. This closes the motor circuit through. the resistances 43, as hereinbefore described, starting the motor. The coils 21 are then initially energized with the rush ofcurrent in starting, so as to attract the armatures 22, rendering the latch 15 ineffective and also closing the exhaust port- 47 to the piston chamber 7.

As soon as the motor speeds up, the cur-l rent falls sufficiently to permit the armatures 22 to drop away, thus opening the exhaust port 47 to the piston cylinder 7. The piston 8 will then be moved downwardly by the spring 49, and since the4 latch 15 will now engage the arm 44, the movement of the piston 8 will operate the switch .arms 10 to connect the contacts 11 and 13 and thus short-circuit the resistances 43. The pressure in chamber 2 and the unloading cylinder 3 will also be rapidly vented through the port 47, until the pressure has fallenA sufliciently to permitsp'ring 48 to move the,n valve 30 and thereby open a direct atmospheric vent from the piston chamber 7 to v the exhaust port 31. The fluid pressure on f the unloading piston 4 being relieved, the suction' valve 6 will be permitted to close :lindi allow the compressor to operate under oa f It will be noted that the time between the starting of the motor and theA loadingv of the compressor is governed not vonly by thel current input to the motor "but also by they time necessary to exhaustfthe fluid pressure from the unloading cylinder'. This ensures the motor being at full speed before imposing the load on the compressor.

Should there occur an interruption of the line circuit between the cutting in and cutting out points of the governor, the action of restoring the parts to their\off or open positions Vandthe unloading of the compressor will be accomplished in the same manner as hereinbefore described, with the exception that there will be no movement of any part" of the pump'governor.

If, while the compressor is in operation, the current value should rise sufficiently above full load, the coils 21 will be energized sufliciently to cause the armatures 22 to move forward and trip the latch `15, thereb permitting the piston 8 tomove downward) ly and cause the switch arms to open the 'motor circuit.

The starting resistance is protected by means of the blow down port 46 through valve 30, since if the motor fails to start, the pressure will be depleted through this port to a point sufiicient to allow spring 48 to o n valve 30, after a time well within the sa e limits necessary to protect -the resistance vagainst burn out and since the latch 15 during this period would be rendered ineffective bythe movement of armatures 22, it will be readily seen that when the valve 30 opens, the switch portion will also promptly open.

Having now described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. In a motor controlling device, the combination with a resistance, of a switch mechanism movable to an initial position for connecting said resistance `into the motor circuit and adapted upon a further movement to a final position to short-circuit said resistance, means for moving said switch mechanisml to its initial position. and a spring for moving said switch mechanisml to its final position upon the reverse movement of said means.

2. In a motor controlling device, the combination with a resist-ance, of a main switch arm having an initial position for connecting said resistance into the motor circuit and a final position for short-circuiting said resistance, an auxiliary switch arm constitilting a fulcrum for the main switch arm, meansfor moving said switch arms to the initial position, a latch for holding said 'auxiliary switch arm, and a spring for mov-l ing .said main switch arm to its first position upon release of said means.

'3g/In a motor controlling device, the com- Biliation with a resistance, of a main switch arm having an initial position for connecting Said resistance into the motor circuit and another position for short-circuiting said resistance, an auxiliary switch arm pivoted to the main switch arm, means for moving said switch armsl to the initial position, a spring acting on said switch arms and adapted to be compressed upon movement of the switch arms to their initial position, a latch adapted to lock the auxiliary arm against movement upon a predetermined decrease in current flow to the motor, to permit the spring to act on the main switch arm and move same to its position for cutting out said resistance from the motor circuit.

4. The combination with a motor for operating a fluid compressor and la compressor governor operated according to the pressure of fluid compressed by the compressor for controlling a shunt circuit, o a magnet controlled by said shunt circuit, a switch device for controlling the motor circuit, means operated by said magnet upon energization for effecting the movement of the switch device to 4close the motor circuit, and means operated by said magnet upon deenergization for releasingsaid switch device to open the'motor circuit.

5. The combination with a motor for operating a fluid com ressor and a compressor governor operated y variations in pressure of fuid .com ressed by the compressor for controlling t e opening and closing of a shunt circuit, of a resistance, a switch device l for controlling having an initie. position in which said resistance is connected into the motor circuit, and a final position in which seidresistance is cut out, a piston for operating said switch device, e magnet coil in the shunt circuit, means operated upon energization of said coil for eilecting the suppiy of fluid under pressure to said piston zor moving the switch device to its initial position, e spring tending to move said switch device to its final position, and means operated upon a predetermined decrease in. current in the motor -circuit for causing sei@L spring to move sei. switch device to its final positief:Ac

ln e motor controlling device, tir oination with a switch device for control the motor circu o; e nienus"' operates. device :for inifziellgv operet c swr n device to ciose the motor circuit, r pressure operated means for hol switch device closed position release fr the menueiy operated dezfioet Y. The combination e rector for opn @rating a compressor, e switch device motor circuit, ineens opersted upon e predetermined decrease J:ie pressure ci compressed 'cy the pumpior eiec'ing mover ci' seid switch device to close the o w cuit, ande in el net or centroid @ne cneration csere;

means and opcrct d .pon failure ci? current in the motor ci.. t for ef'ectmg ne movement of switch device to its poei= tion.

move said switch device to its 8. In a motor controlling device, the cinnbination with a resistance and a switch device having an initial position in ywhich said resistance is cut into the motor circuit and a. i'inal position in which said resistance is short-circuited, of a piston operated by fluid under pressure for moving said switch device to its initial position, a sprinfr tending final pos-ition, and means operated upon a predetermined decrease in the How of current in the niotor circuit venting,r iuid from said lHSG-i miie combination with a motor for operating e {iuid compressor, of a resistance,

c main switch arm having an initie-i position for connecting said resistance into the motor circuit and a final position for cutting scid resistance out of the motor circuit, an auxiliary switch arm pivoted tc the main switch erin, e ietcii connected to the auxil y swi't i arm, a pump governor operetedaccording to the pressure of fluid compressed by the compressor for controlling a shunt circuit, a magnet coil in said shunt circuit.A an armature controlled by said coil for holding said latch, a. magnet coil in the motor circuit, and an armature controlled by said last mentioned coil for tripping said cto testimony whereof I have hereunto set BUirroN s. AIKMAN.

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