US2027576A - Circuit controller - Google Patents

Description

M, N357 H. P. CHANDLER @225276 CIRCUIT CONTROLLER Filed June 8, 1955 /PU/V/V//l/J-I Patented Jan. 14, 1936 UNITED STATES PATENT OFFICE CIRCUIT CONTROLLER Application June 8, 1933, Serial No. 674,901

9 Claims.

My invention relates to control devices for electric motors.

One of the objects of my invention is to provide a device for controlling the current to the motor upon starting.

Another object is to provide means for supplying a small current to the motor eld when not in use in order to keep the motor warm and dried out. This is particularly advantageous Where the motor is employed in damp places, such as mines.

Another object is to provide means for preventing a dangerous rush of current through the motor when the motor is first energized.

A still further object of my invention is to provide means for maintaining the circuit closed under predetermined voltage conditions but permitting the circuit to the motor to be opened automatically when the line voltage drops below a predetermined amount.

Another object of my invention is to automatically open the circuit to the motor should the current operating the motor exceed a predetermined amount for a predetermined time.

A still further object of my invention is to permit the stopping of the motor from a point at a distance from the motor or the control device at will of an operator.

Further objects of my invention will be apparent to those skilled in the art as I disclose my invention herein.

My invention resides in the new and novel construction, combination, and relation ci' the Various parts and circuits herein shown and described in the drawing and specification.

In the drawing- Fig. 1 is a schematic arrangement of the essential parts and circuits.

Fig. 2 shows a View in elevation in partial section of my invention to show largely its manner of mounting within a casing and three positions of the switch which I employ.

Fig. 3 is a View of the magnetic holding device for maintaining the switch closed under normal conditions.

Fig. 4 is a sectional View on the line 4 4 or Fig. 3.

Fig. 5 is a sectional View on the line 5 5 of Fig. 1 showing the switch blade in its fully closed position.

Fig. 6 is a view in partial section taken on the line 6 5 of Fig. 2 and shows a method of mounting terminal and switch blade to the casing and method oi manually operating the switch blade to its closed position.

Fig. 7 is a perspective view of an electrothermally controlled switch.

In the preferred embodiment of my invention l provide a metal casing or retainer I which shown more in detail in my Letters Patent 1,927.2,979 issued September 11, 1934.

Secured to the casing is an insulating support member 2 and upon which an insulating base member 3 is mounted. The support memberv 2. aiiords a space between the receptacle I and the base 3.

Mounted upon the base 3 are a plurality of terminals il, 5, E and l. Mounted upon the inner wall of the receptacle i is a terminal 8 with an interposed insulating block Ei which may be of wood or other insulating material.

l rivotally mounted in the terminal member 4 is a knife blade i@ shown in its fully closed or runmng position in full lines, and in its partially closed or starting position and in its d oii position in broken lines.

My invention also includes a resistance elenient il which is included in the main circuit through the motor when the switch blade is in its s trting position, but is fully cut out or" circuit when the switch blade is in its running position.

My invention also includes a thermal switch I2 shown in Fig. '7 and comprises a U-shaped element i3 of bimetal connected with its free ends connected to the terminals I4 and l5 which in turn are mounted on the base 3. Attached to the unsecured end of the U-shaped thermal element i3 is an insulating member IB and to this insulating member I0 is secured a Contact member l1.

Mounted upon the base 3 is a terminal member it provided with an adjusting screw I9 arranged to make and break contact with the member I'I, depending upon the flow of current through the thermal element I3.

Secured to the blade I0 is a member 20 of magnetic material.

Mounted upon the base 3 is a coil 2I having end holesl 22 secured to a core 23 arranged to act upon the member 2li when the switch is in its fully closed position to hold it in positionwhile the coil 2I is energized to a predetermined amount.

The switch blade I0 is provided with one or more coil springs 24 constantly acting to move the switch blade to its off position.

As the switch blade is moved from its off position toits running position, it will have an intermediate or starting position where it will contact with the terminals 5 and 6, but when the blade is in its running position it will contact with the terminals 5 and l but not with the terminal 6, as shown in Fig. 5;

The switch blade is pivotally secured to the terminal d and the pivotal shaft 25 provided with an insulating member 25 may be made 'suoiently long to extend through the side wall of thel receptacle I and is further insulated therefrom by means of the insulating bushing 26 and the shaft 25 has its inner end secured to the blade Iii to move the blade from its oi position to its running position when the handle 2i' secured to theV outer end of the shaft 25 is manually operated.

The switch blade may be operated through a mechanism producing delayed action when the switch has reached its starting position and such operating mechanism is shown in my Letters Patent above referred to.

Having described the various elements aside from the conductors which form a part of my invention, I will now describe the various connections and operation of my invention.

The invention is provided with terminals '28 and 25 for connecting to source of power L and L respectively. The terminal 23 is connected to the switch terminal 4i by the conductor 30 thus the terminal i is constantly charged when the device is connected to the source of power. When the switch is in its off position the terminal 8 will be energized and current Will flow through the conductor 3i, resistance. 52, conductor 33, to the field F of the motor M and then through the field F, conductor 3d and terminal 2S to the power line L'. This permits what I term a. warming current to flow constantly through the field F when not in use, thus keeping it warm and dry and the resistance 32 is adjusted to give the proper amount of current based on the voltage of the source of power.

When the operator has moved the switch blade to the starting position the terminals 5 and will be energized. Current will flow from the terminal 5 through the conductor 35, holding coil 2l, conductors 35, 31, 33, iield F, conductor Sl, terminal 29 to L. Ihis will place the field F directly across the source of power I r-L in series with the interposed holding coil 2i, thus fully energizing the eld in advance of the switch being fully closed.

Current will also iiow from the terminal 6 through the conductor 33, resistance II, conduotors 39 and :iii to the armature A, then through the conductor Sil and terminal ZSVto the source of power L.

With the blade in the starting position the operator maintains the switch in the starting position until he feels that the motor has picked up such speed as the current controlledby the resistance I i will permit or if the starting mechanism referred Yto in the above Letters Patent is employed the operator of course is compelled to hold the switch in the starting position for a short interval or" time before he is able to move it to the running position. Y

When the operator moves the switch blade to the running position the terminal 6 is rendered dead (see Fig. 5) and the terminal 'I is energized, while the terminal 5 remainsl energized. Current now iiows from the line Lvthrough the terminal 28, conductor 30, terminal 4, blade I0, terminal l, conductor LlI, fuse l2 (if used), conductor 43, thermal switch l2, conductor 4I),

armature A, conductor 34, terminal 29 to lin L', thus placing the motor in fully running condition.

It will be noted that the 'main' current to the motor will flow through the thermal switch I2 and so long as this current does not exceed a predetermined amount for a predetermined time the switch I2 will not change materially, but if the sustained current exceeds a predetermined value then the thermal switch I2 will be heated and the contact I 'I will engage the adjustable contact I 9 thus closing a circuit which will shunt the coil ZI.

When the contact I7 engages the contact I9 the shunt about the coil 2l will comprise the conductors 36, @4 and 65, terminal I8,`contacts I S and I'I, conductors 45 and 47. Y

The Yengaging of the contacts I'I and I9 and short-circuiting of the coil 2l will deenergize the coil 2l and the blade IB will be released and the spring 24 will return the blade to its startingposition. f e

If it is desired to open the switch at a point remote from the control device conductors 48 and 69 are provided which lead to the terminals 5i? and 5i respectively and from these terminals leads 52 and 53 may be run wherever desired and connected to a switch 54 which when closed will shunt the coil 2I the same as is the case when the contacts I1 and I9 engage.

It will be evident to those skilled in the art that from the above disclosure it would be possible to modify my invention without departing,- from the scope thereof and therefore I do not wish to be limited other than by my claims.

I claim:-

i. The Vcombination with an electric motor having a eld winding and an armature, of a circuit controller operable to off, starting and running positions adapted to supply electrio power to the motor, the said controller having a switch blade movable to each of the said positions and having atleast one contact for each position and selectively engageable by the CIU switch blade, means for connecting the arma- .f".

ture to a contact in the running position, a resistor and means for connecting the armature in series with the resistor and to a contact in,

the starting position, a second resistor andl Y means for connecting the said field winding in series with the second resistor to a contact in the off position to energize the neld winding below normal to warm the winding when the motor is inoperative and the armature deenergized.

2. The combination with an electric motor having a iield winding and an armature, of a circuit controller movable to off and running positions to supply electric current to the armature and ield winding, the controller being provided with at least one contact for each position and a switch blade movable into selective engagement with the contacts at will of an operator, a normally open and thermally controlled h switch and means for connecting the motor armature and switch in series to a contact in the running position, electrically operated holding means to hold the blade in the running position and connected for energization by the current through the eld winding when the blade to release the blade, means to return the blade to the off position when released, a resistor and means to connect the resistor and the field winding in series and to a contact in the off position to energize the winding below normal when the motor armature is deenergized.

3. The combination with an electric motor having an armature and a field winding, of a controller manually movable to 01T and running7 positions and automatically movable from the running to the ofi positions and to control electric power to the motor, the controller being provided with only one switch blade and at least one contact for each said positions and selectively engageable by the blade, a resistor and means to connect it successively in and out of series with the armature as the blade moves from the 01T to the running position, a second resistor, means to connect it to the field winding and to a contact in the ofi position to sub-energize the eld winding to heat the same while the armature is deenergized and automatic and manually releasable holding means to hold the blade in the running position.

4. The combination with an electric motor having a eld winding and an armature, of a circuit controller operable to off and running positions to supply the motor with electric power, the controller being provided with at least one contact for each said position and a switch blade arranged to selectively engage the contacts, a coil operated holding means arranged to releasably hold the blade in the running position and means to connect the coil to the field winding, means to return the blade to the ofi position when the holding means releases the blade, a resistance element and means to connect the resistance element to the field winding and to the oir contact to energize the field winding below normal when the motor armature iS deenergized.

5. The combination with an electric motor having a iield winding and an armature, of a circuit controller operable to an off and to a running position to supply current to the motor, the controller having at least one contact for each position and switching means to selectively engage the contacts, holding means and means to connect the holding means to the iield winding to operate the holding means by current through the iield to releasably hold the switching means in the running position, thermally operated means connected to the holding means to eiect the release of the switching means when the sustained current through the armature exceeds a predetermined value, manually operable means connected to the holding means to effect the release of the switching means at will of an operator, a resistor and means to connect the resistor in series with the ield winding and to a contact in the oi position to sub-energize the winding to maintain heat therein when the motor is inoperative.

6. An electricmotor controller comprising a switch blade movable to off, on and intermediate positions and at least one contact for each position and selectively engageable by the blade, an armature resistor connected to the intermediate contact, a field resistor connected to the off contact, the switch blade movable to cut either of the resistors out of circuit when the blade engages either of the other two contacts and to cut both resistors out of circuit when the blade engages the on contact, electro-magnetic means to normally hold the blade in the on position and releasing the same when de-energized, a device for shunting the holding means and having a thermal operating element electrically connected to the on contact and operable to shunt the holding means only when the blade engages the on contact and the sustained current through the thermal element exceeds a predetermined value and means to return the blade to the o position when the holding means is shunted.

7. A circuit controller for a motor, comprising a switch blade operable manually in one direction and a plurality of contacts selectively engageable by the blade, spring means constantly urging the blade to engage one of the contacts and a field resistor connected in circuit and to the said Contact, a second contact engaged by the blade, a holding coil connected to the said second 'contactand energized when the blade engages the second contact and arranged to hold the blade in engagement with a third contact, a thermo-statically controlled switch connected to and energized from the said third contact to shunt the holding coil when the sustained current through the thermal switch exceeds a predetermined value, a fourth contact to be engaged by the blade in. moving from the rst to the third contact and an armature resistance connected in circuit and to the said fourth contact and arranged to be cut out of circuit when the blade is in engagement with the third said contact and manually controlled means to shunt the holding coil to de-energize the same.

8. A motor controller, comprising a manually operated switch blade having oil, starting and running positions, a contact corresponding to each position and engageable by the blade, a holding coil to maintain the blade in its running position when the coil is energized to a predetermined degree, a thermo-statically controlled switch to effect the deenergization of the holding coil, an armature resistance to control the initial rush or" current and connected in circuit with the contact corresponding to the starting position, a resistance connected in circuit with the contact corresponding to the off position, and a contact engaged by the blade in both the starting and running positions and connected to the holding coil to energize the coil while the blade is in the starting and running positions and to hold the blade in the running position until deenergized as above provided.

9. The combination with an electric motor having an armature and a field winding, of a controller manually movable to off and running positions and automatically movable from the running position to the oil position and to control electric power to the motor, the controller being provided with only one switch blade and at least one contact for each said positions and selectively engageable by the blade, a resistor and means to connect it successively in and out of series with the armature as the blade moves from the off position to the running position, a secondresistor, means to connect it to the field winding and to a contact in the off position to sub-energize the field winding to heat the same while the armature is deenergized.

HOMER P. CHANDLER.

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