US2232625A - Electric switch - Google Patents

Description

Feb. 18, 1941. .e, w. OKEEFFE ELECTRIC SWITCH Filed D60. 27, 1958 3 Shuts-Sheet 1 msu/afxon Feb. 18, 1941. G. w. O'KEEFF-E ELECTRIC SWITCH Filed Dec. 27, 1938 3 Shuts-Sheet, 2

Patented Feb. 18, 1941 UNITED. STATES PATENT OFFICE ELECTRIC SWITCH Application December 27, 1938, Serial No. 247,783

5 Claims.

This invention relates in general to electric switches and particularly to electric switches adapted to the control of industrial motor circuits.

Motor controllers of the above type usually include at least three different types of switches. In order that these controllers may utilize as little space as possible, the starters of the prior art have been crowded into a small space and simplicity of assembly of the parts has suffered considerably from such crowding. Due to the fact that during its normal life a motor starter is operated a great many times, often handling heavy currents. it is very desirable that the various elements thereof be readily available for inspection. It is further very desirable that certain elements, such as the contacts, be easily removable in order that they may be replaced when necessary. In order that motor starters oi the above type may be utilized for various motor circuits and under various predetermined conditions, the electromagnetic coil should be easily replaceable by a coil designed for another voltage or frequency. It is likewise desirable that the heater element of the thermal overload relay be easily replaceable by a heater element designed for another predetermined current value. It is further desirable that the above inspections and replacements be easily effected without removal of the line wires from the terminals.

The present invention obtains the desirable characteristics above stated by utilizing a unit construction of the several important parts of the motor starter. The fixed contact of one pole, the terminals for the line wires connected to that pole, the insulation mounting for the terminals and contact, and the arc interrupting chamber for such contact are all removable from the supporting plate as a single unit in a very simple manner. Similarly the electromagnetic movable contact operator is very easily removable from the supporting plate as a single unit.' The thermal overload relay is removable as a single unit from its supporting base without necessity of removal of the line wires with which it is in circuit. Although the above unit has been made removable merely by loosening one or perhaps two bolts or screws, a simple means is provided for perfect alinement of the contacts and a very rugged construction of moving parts is obtained.

It is therefore an object of the present invention to provide a rugged motor starter in which inspection, replacement or repair are effected simply and easily.

It is also anobject oi the present invention to provide a unit construction of the contact assembly wherein individual poles are mounted on rigid conductive plates.

It is also anobject oi the present invention to I provide an individual arc chamber per contact which provides efllcient arc extinguishing and permits an easy means for contact inspection.

It is also an object of this invention to provide in apparatus of the above type a complete electromagnetic contact operator assembly which is easily removable as a unit from the other elemerits of the motor starter.

It is a further object of this invention to provide a flexible, easily detachable connection between the movable contact assembly support and the armature of the solenoid.

It is also an object of the present invention to provide in apparatus of the above type a thermal overload relay, including a heat element, easily detachable from its support base, thereby permitting ease of inspection and replacement.

It is a further object of this invention to provide a thermal relay in which the heater element is provided in a slot in the melting alloy container.

It is also an object of the present invention to provide an envelope rigidly fastened in the cover of the enclosing case in which instructions a for the installation of the starter may be placed.

Objects and advantages other than those above described will be apparent from the following description, when read in connection with the accompanying drawings, which illustrate a sin 35 gle embodiment of this invention and in which: Fig. 1 is a front elevation thereof with the enclosing case removed:

Fig. 2 is a side elevation, partly in section,

of the construction shown in Fig. 1, with the 40 enclosing case included;

Fig. 3 is an exploded side view of the construction shown in Fig. 2 without the enclosing case; Fig. 4 is a section view taken along the line IV-IV of Fig. 2; I

Fig. 5 is a view of the construction in Fig. 4 with the contact and bridging member removed; Fig. 6 is a section view through a part of the thermal overload relay taken on the line VI-VI so of Fig. 2;

Fig. 7 is a detail front elevation view showing the connection of the armature to the contact supporting member;

Fig. 8 is a detail view of the thermal overload u toning bolt 18 threaded into the plate.

relay contact structure taken on the line VIII- vrn of Fig. 8: and

Fig. 8 is a diagram of connection which may be utilised with the present invention.

As shown in the drawings, a main supporting plate II has an upper bent section II held in position by the bracket 81. This heavy steel plate 88 forms the chassis of the starter and is supported on the casing 81 by means of fastening members ll acting through apertures 88. Separate pole units 18 are mounted in closely fitting apertures in the horisontal portion of the plate and these pole units I8 are therefore easily held in alinement merely by a sin lg lfmiasremovable pole unit 78 includes the fixed contact support I! of insulating material, the fixed contact 88 held in position by washer l8 and nuts 8| forming the line terminals. and the enclosing chamber 88 slidably mounted on the fixed contact and held in the position shown in Fig; 2 by spring 38.

By utilising the unit pole construction, each unit separate from the other, several advantages are obtained. The pole units are readily removable. Each unit may be held in alinement with a single fastening member. In prior art starters, the various pole mountings have been combined in a single piece of insulating material. It was therefore practically impossible to obtain one large molded base free from a twisted or warped condition such as would allow true contact alinement when the contacts are mounted thereon. The separate unit construction also provides long vertical self-cleaning surfaces between poles and also provides long creepage surfaces between phases, thereby insuring safety of operation in dimcult atmospheric conditions. The fixed contacts 38 are supported in the housing 82 by means of a washer 88 fitting both against a shoulder of the fixed contact and a shoulder of the housing and held in position by the nut 8| forming a terminal. The contact is prevented from turning by lllg 82 riding in a slot 88 in the housing.

The movable contact assembly, including the core II. the coil II, and the movable armature It. also forms a single unit designated generally as II. This entire operator assembly unit is removable from the frame 28 merely by removing the magnet cover 88 and the magnet connections. The magnet cover. relay reset button 82, and the coil supporting bolts 88 are removable as a unit. The coil supporting bolts 88 are covered with insulating tubing 81 which cushions the magnet coil and prevents chafing thereof.

The solenoid and contact operator assembly II, as shown more clearly in Fig. 3, comprises generally a core ii, a coil ii and an armature i8.

Armature II has side plates ll which extend upwardly above the armature to provide for connection thereof to the movable contact support bar. These plates 14 have lugs 18 which cooperate with extensions 88 on the core side plate 88 to form guides at the lower end of the armature- The armature is guided at its upper end by extending lugs II which are integral with the core side plates 88 and are bent around the armature side plates ll, as shown more clearly in Figs..3 and i.

The movable contact support bar I is a strong steel channel also having unit type insulators on which the movable contacts 28, provided with arcing tips 24, are supported. This unit construction of the movable contacts cooperates with the fixed contact units to provide the separated pole units. The bar it is flexibly connected to the armature side plates 14 in order to avoid transmission of vibrations from the coil to the contact. This flexible connection isshown more clearly in Fig. '7. Two arms II, the upper ends of which are rigidly fastened to the bar II, are biased away from each other by the spring i8. The ends of each bar are bent into a U shape, the tips of which have extension ll extending through holes in the side plates ll. Notches H are cut in the arms I! which coact with notches in the upper end of the side plates ll. Bearing cylinders II are held in place by pins 28 to form additional bearing surface. The contact assembly is therefore easily removed from the armature and magnet assembly by compressing the arms it toward the other and disengaging the ends i8 and pin 28 from the side plates 18.

The-movable contacts 23 for each pole unit are carried on a conductive bridging member 28, as shown in section in Fig. 2 and as shown in detail in Figs. 4 and 5. A pin 28 having a flat and wide extension 88 on the bottom thereof is slidably mounted in the support 2i and is biased upwardly by the spring 21. The housing 2| has a slot 22 in the bottom thereof. In order to remove the movable contact, a screw driver is inserted in the slot in the pin 28 and turned a quarter of a turn from the position shown in Fig. 4. The extension 88 and the slot 80 thereby coincide and the bridging member 28 is allowed to drop free. As the slot 22 is at right angles to the slot Iii, the pin 28 stays in position unless turned another quarter of a turn so that the extension 88 coincides with the slot 22, upon which the pin may be removed from the housing ii.

The coil II is positioned relative to the core I! and the armature i3, by means of the tube 81 and bent over armature guides 15 on the core side plates 68. The four lugs 15 form a rectangle which makes a snug fit in the rectangular hole in coil II. The tubes 81 of insulating material are held against the lower face of coil H by the bolt 88, when coil II is in position as shown in Figs. 2 and 3. Upon disconnection of the armature from the contact bar supporting arms ii, the armature may be readily dropped out of the core and coil. The coil is therefore readily re-- movable from the core for inspection or replacement by a coil of another voltage or frequency. The side plates 88 of the core member have lugs 12 which fit in holes 88 in the plate 28 to aid in support of the operator assembly. The plates 88 likewise have lugs 13 fitting in holes 94 in the cover plate 84 so that by tightening bolts 88, the operator assembly is securely positioned. The bolts 88 are provided with self-locking washers 81. Shading coils ll aid in preventing chattering of the armature II.

The thermal overload relay shown generally at 38 is also formed as a unit. This relay is mounted on a bracket ll as shown more clearly in Fig. 3. The relay comprises essentially an insulation base 38 which with its cover 40 completely encloses the heater element 48. The heater element acts on a solder pot type of release for the switch arm 49, thereby actuating contacts 85 and 56. The relay 38 is so formed that the heater element may be readily removed for inspection or replacement without the necessity of removal of the relay, merely by removal of screws 42 which function also to fasten electrical conductors to terminals 92.

The heater element 43 is connected by terminals 90 and 92in the line circuit'as shown in the diagram of Fig. 9. The heater element 43 is held in place between two extensions 48 of the solder pot 45 by two screws 44. The extensions 48 are formed by a milling operation in order to obtain a low energy device having great accuracy. Pot 45 has a low temperature melting allow which, when heated to a predetermined temperature by the heater 43, melts and allows the tripping pin 46 to rotate, thereby allowing switch arm 49 to move to the left, as shown in Fig. 3. Movement of the arm 49 moves the switch operator 54 to open the normally closed contacts 56 which are closed by the bridging member 55. A slot 53 permits disengagement of the arm 48 and operator 54 upon removal of the heater element assembly.

After the relays operate the molten alloy quickly solidifies and allows the relays to be reset. The resetting is performed by movement of the reset button 62 against the bias of spring 63, thereby moving arm 64, having insulating actuators 65 thereon, to the right in slot 88, as seen in the drawing, which moves the switch arm 49 to normal position. The spring latch 4'! slides past notches in the head of the pin 46. When the cover 58 is on the casing 51, the reset button 62 is operated by an auxiliary reset button extending through the cover and biased out wardly by a spring 8|.

The circuit through the magnet H which is controlled by either or the thermal overload relay contacts may beentirely isolated from the main circuit controlled by contacts 25 and 33 and also from the circuit of the heater element of the thermal overload relay 38. As shown more clearly in Fig. 8, the conducting member 55, which bridges the contacts 56, is insulated from the switch actuator 54 by means or a cylinder of insulation 52. The contacts 68 are insulated from the other elements by the housing 39. There is therefore a control circuit for the magnet H from the terminal 88 through the contacts 56, 55 0! the left hand thermal overload relay shown in Fig. 1, left hand magnet coil terminal 91, magnet coil ll, right hand magnet terminal 91, right hand thermal overload relay contacts 55, 58 to the right hand terminal 95. This circuit may be entirely isolated and utilize a voltage entirely different from that controlled by the main contacts. Tabs 89 are utilized to identify the terminals by a letter or numeral marked thereon.

In the present embodiment, line voltage was used for this control circuit and the terminal 86 is connected to one of the main terminals as shown in the connection diagram of Fig. 9. In the diagram 9. conventional start stop push button is connected to the terminals C, Cr and 03. A motor is shown connected to the terminals '1', "1: and Ta.

In order to provide a readily accessible container for installation and operating instructions, an envelope 58 is securely fastened on the upper inside surface of the cover 58. The instructions may be placed in the envelope rather than pasted on the cover and may be removed when utilized. This avoids the necessity of removin the cover in order to read the instructions.

Although a single embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

It is claimed and desired to secure by Letters Patent:

1. In a circuit maker and breaker, the combination of a fixed contact supporting member with a unitary electromagnetic movable contact operator assembly, said assembly comprising a laminated magnet core, an armature movable relative to said core and constituting the center leg thereof, an extension member on said armature, a movable contact supporting member flexibly connected to said extension member, guiding members for said armature, a magnet coil surrounding said armature, and means comprising said guiding members for positioning said coil relative to said core and for easily removably attaching said operator assembly as a unit to said fixed contact supporting member.

2. A circuit maker and breaker comprising a supporting plate, a fixed contact assembly easily detachably supported on said plate, said assemblycomprising separate insulation contact supports for each circuit made and broken, an electromagnetic movable contact operator unit supported on and easily detachable as a unit from said plate, said unit comprising a magnet, an armature, a contact carrying member, a plurality of movable contacts, and insulation members on said member separate for each circuit made and broken for supporting said contacts, said insulation members being arranged in alinement with said fixed contact insulation supports.

3. In combination, a supporting plate, an electromagnetlc operator assembly comprising a magnet core, a coil and an armature, means for detachably supporting said assembly on said plate as a unit, said means comprising means for positioning said coil relative to said core and said armature.

4. In an electromagnetic contact operator assembly unit, a laminated magnet core, an armature movable relative to said core, a member supporting a plurality of pairs or movable contacts, means for flexibly and easily detachably connecting said armature directly to said member.

5. The combination of a supporting plate and an electromagnetic operator assembly comprising a magnet core, a coil, an armature, a member supporting a plurality of movable contacts and means for easily detachably connecting said armature to said member, with means for detachably supporting said assembly on said plate as a unit, said means comprising means for pcsitioning said coil relative to said core and said armature.

GEORGE W. OKEEFFE.

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