US1860493A - Grid resistance - Google Patents

Description

May 31, 1932. H. E, CAMPBELL GRID RESTSTANGE Filed Jan. 2l, 1929 vivre..

.549. 4 valant... ,2.5 A.

mu A TTORNEYS QW/5 A Patented May 31, 1932 UNTE STTES PATENT oFFlcE.

HARRY E. CAMPBELL, OF MILWAUKEE, WISCONSIN, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO CUTLER-HA1VI1VIER, INC., A CORPORATION OF DELAWARE GRID RESISTANCE Application led January 2l, 1929. Serial No. $33,900.

rlhis invention relates to improvements in grid resistances more particularly adapted for use with electric controllers and starters of various kinds.

It is one of the objects of the present invention to provide a grid resistance formed of cast iron or other metal in which each resistance grid or element consists of a number of parallel strips of thin metal connected together in staggered relation at their ends by return bends to provide a continuous length of material having slotted attaching lugs at its opposite ends.

A further object of the invention is to provide a grid resistance having means for maintaining assembled grids in position even though the grid holding members have become loosened.

A further object of the invention is to provide a grid resistance in which the grids when assembled in a bank are interlocked together in such a manner as to rigidly hold the grids together and form electrical contacts between pairs of terminal lugs to provide a continuous circuit'from one end of the bank to the other.

A further object of the invention is to provide a grid resistance which when assembled in a bank, individual grids may be removed or replaced without disturbing the other grids of the bank.

A further object of the invention is to provide a grid resistance which is of simple construction, is strong and durable and is well adapted for the purpose described.

With the above and other objects in view, the invention consists of the improved grid resistance and its parts and combinations as set forth in the claims, and all equivalents thereof.

In the acompanying drawings in which the same reference characters indicate the same parts in all of the views:

Fig. 1 is a longitudinal sectional view of a bank of the grid resistance units taken on line 1--1 of Fig. 2;

Fig. 2 is a transverse sectional view thereof taken on line 2-2 of Fig. 1; and

Fig. 3 is a top view of the grid resistance bank, the supporting frame being broken away.

Referring to the drawings the reference numeral 5 indicates sheet metal frame members of rectangular 'form and provided with reinforcing flanges 6 having openings formed therein for attachment to a support. T he frame members are spaced apart and are connected together by horizontally extending spaced rods 8 which extend through the frame members and are adjustably connected thereto by nuts 9. The nuts are threaded on the rods on each side of each frame member to rigidly clamp the rods thereto as clearly shown 1n Fig. 1. Portions of the rods between the frame members are enclosed in insulating tubes 10 and the terminal lugs 11 and 11 of cast iron grids 12 and 12 extend partly around said insulating tubes 10. Each upper grid consists of a pair of terminal lugs 11 having alined slots 13 which open edgewise in the same direction as shown in Fig. 2. The `lugs of each upper pair are connected together by a thin strip of metal 14 of serpentine shape in which the parallel portions 15 of the strip lte joined together by return bend portions The lower grids 12 are of the same shape as the upper grids and have strips 14, parallel portions 15 and return bends 16', and said strips 14 are connected to terminal slotted lugs 11 in the same manner as the upper strips and lugs are connected together. Each slotted lug is thicker than the strip portion 'and projects outwardly laterally on both sides of the strip to form shoulders 17 of circular shape. Washers 18 having annular laterally projecting shoulders 19 are mounted on the insulating tubes 10 between alternate adjacent lugs, and the annular flanges 19 of said washers extend over the annular shoulders 17 of the adjacent lugs 11 to prevent the accidental removal of the grids in the Lvent that the nuts 9 should become loosene Washers 20 and 21 and a spacer tube 22 mounted on the insulating tube 10 and interposed between the frame members and the opposite sides of the bank of grids provide for clamping the grid members in position by means of the inner nuts 9 and when thus tightened the outer nuts 9 are then threaded firmly against the frame members to clamp the rods to said members and to lock the inner nuts in position.

To provide a circuit through all of the grids from one end of the bank of upper and lower grids to the other, insulating washers or disks 22 are interposed between alternate pairs of slotted lugs and said washers are staggered with relation to the insulating washers 22 mounted on the opposite rodl 8.

Terminal connector posts 23 mounted on one of the rods and on the outer sides of the two end grids of the bank provide for connecting electric circuit wires 24 thereto. As thus connected, referring to Fig. 3, the current will flow rearwardly from the left hand terminal 23 through the lower grid 12 which is connected to the upper grid 12 and then forwardly through the said upper grid to `the next adJacent lug which forms part of the next lower grid and thus back and forth to the right hand terminal member 23.

Particular attention is directed to the fact that the lugs of a grid extend inwardly toywards each other so thatthe outer edges of the lugs are substantially flush with the outer edges of the outer parallel portions or legs of the grid strip to form a compact structure. Furthermore the lugvslots 13 open edgewise in the same direction to permit the easy revmoval of any one of the grids when the nuts have been loosened suliiciently to permit the lug lshoulders 17 to disengage the washer flanges 19.

The invention also contemplates the use of two or more grids placed together and the connecting and insulating the lugs of connected pairs of grids to provide greater current capacity.

From the foregoing description it will be seen that the grid resistance is of very simple construction and is well pose described.

y What Iclaim as my invention is:

1. vThe combination with a grid resistance and supporting means therefor including a rod, said grid having a lug with an open slot to receive said rod, of a member loosely mounted on said rod and movable relatively adapted for the pur- 4to said lug into and out of interlocking engagement therewith, said-member when in Vinterlocking engagement with said lug affording said lug additional securement to saidrod.

` 2. A grid resistance, comprising insulated rods, resistance units of grid formation having" inwardly projecting slotted lugs which extend partly around the insulation of the rods, said lugs having laterally extending shoulders, flanged washers interposed between-some' of theA lugs and engaging the shoulders to preventaccidental removal of thergrids, the slots of said lugs opening in one direction, insulating' washers interposed between alternate pairs of lugs on each rod,

the insulating washers between lugs on one rod being staggered with relation to the interposition of the insulating washers on the other rod, terminal members for the bank of grids, and threaded means for clamping the lugs and the washers and the terminal members rigidly together.

3. A grid resistance, comprising insulated rods, resistance units of grid formation having inwardly projecting slotted lugs which extend partly around the insulation of the rods, said lugs having laterally extending annular shoulders, washers interposed between some of the lugs and having laterally extending annular flanges which overlap the annular shoulders to prevent accidental removal of the grids, the slots of said lugs opening in one direction, insulating washers interposed between alternate pairs of lugs on each rod, the insulating washers between lugs on one rod being staggered with relation to the interposition of the insulating washers on the other rod, terminal members for the bank of grids, and threaded means for clamping the lugs and the Washers and the terminal members rigidly together.

ll. A grid resistance, comprising frame members, spaced rods connected thereto, insulating tubes extending around said rods between the frame members, resistance units of grid formation having slotted lugs which extend partly around the insulation on the rods, said grids being alternately positioned above and below the rods and said lug slots opening in one direction, said lugs having laterally extending annular shoulders, washers interposed between some of the lu s and having laterally extending annular anges which overlap the annular shoulders to prevent accidental removal of the grids, insulating washers interposed between alternate pairs of lugs on each rod, the insulating washers between lugs on one rod being staggered with relation to the interposition of the insulating washers on the other rod, terminal members for the bank of grids, and nuts threaded on the rods for clamping the lugs and the washers rigidly together.

5. The combination with a grid resistance and supporting means therefor including a rod, said grid having a lug with an open slot to support said grid on said rod, of a member surrounding said rod and movable along the latter into an interlocking relation with said lug to lock said grid against removal from said rod.

6. The combination with a grid resistance and supporting rods therefor, said grid having lugs with open slots for engagement with said rods, of members surrounding said rods respectively and movable along the latter into an interlocking relation with said lugs to lock said grid against removal fromI either of said rods.

7. The combination with a bank of grid lli) resistances andv common supporting rods therefor, said grids each having lugs with open slots for engagement with said rods, of a plurality of members surrounding each of said rods and each being movable along its respective rod into an interlocking relation With a lug of a grid to look such grid against removal, and means including parts on opposite sides of the bank of grids to con fine therebetween in interlocking relation all of said lugs and members.

8. The combination With a grid resistance and supporting means therefor including a rod, said grid having a lug with an open slot for engagement with said rod and said lug having a shoulder concentric with said rod, of a Washer surrounding said rod and having an annular flange to overlap said shoulder on said lug for locking said grid on said rod subject to release by relative m'cvement of said lug and member along said ro 9. The combination with a grid resistance and supporting rods therefor, said grid having lugs with open slots for engagement with said rods, of members supported by said rods and having parts to be interlocked with parts of said lugs of said grid to lock the latter on said rods, said interlocking parts enabling release of said grid for removal by relative movement of said lugs and members along said rods but said interlocking parts having overlap affording securement of said grid on said rods With a loose assembly of said grid and members.

In testimony whereof, I aix my signature.

HARRY E. CAMPBELL.

Images