US2413414A

US2413414A - Frictional holding means

Info

Publication number: US2413414A
Application number: US517255A
Authority: US
Inventors: John A Obermaier
Original assignee: Individual
Current assignee: Individual
Priority date: 1944-01-06
Filing date: 1944-01-06
Publication date: 1946-12-31
Anticipated expiration: 1963-12-31

Description

Dec- '31, 1945- J. A. oBERMAn-:R

FRICTIONL HOLDING MEANS File'd Jan. 6, 1944 ff bgg/+5 IN V EN TOR. bhp erm'er;

Patented Dec. 31, 1946 UNIT-EDv STATES PATENT OFFICE 2,413,414 FRICTIONAL HOLDING MEANS John A. Obermaier, River Forest, Ill.

"Application January 6, 1944, Serial No. 517,255

, Claims.

,1 y This invention relates to adjustable devices, and has to do with means for frictionally holding in adjustment an arm or analogousmember movable about an axis relative to an associated supporting member.

^ VIt is known in electrical measuring instruments,

for example volt meters'and'electrical pyrometers, to provide an adjustable arm for assuringV that the pointer of the instrument will be at the zero mark o-n the dial when the movable coil of the instrument is deenergized, friction means being provided for holding the arm in adjustment. The friction means commonly used is a known type of spring washer confined under pressure so as to exert pressure on the adjustable arm for holding it in pressure contact with a cooperating surface for holding the arm frictionally in adjustment. That necessitates the use of an additional part, the spring washer, which involves additional operations in assembly and production, and also involves an increase in overall height of the structure to accommodate the spring washer, all of which contributes to increased co-st and is objectionable for that reason and, in certain cases, where space is restricted, isV objectionable as contributing to increased overall height of the structure. While the frictional holding means of my invention is particularly suited for use in electrical measuring instruments having a movable coil, and analogous devices, it is also applicable, in its broader aspects, to a structure having an arm or analogous member pivoted for movement between two cooperating supporting members. In electric switches, for example, a spring washer of known type commonly is disposed between the switch blade and an arm of the associated supporting clip for holding the blade frictionally in adjustment, which is objectionable as involving increased operations and increased cost in material, above referred to.

My invention is directed to the provision of frictional holding means of comparativelyA simple and inexpensive construction and operation, in

vwhich the necessity for providing an additional part, such as the known type of spring washer referred to, is eliminated. More specifically, I provide two supporting or mounting members between which an arm or analogous member is pivoted, one of the mounting members being provided with resilient fingers cooperating with the arm and the other mounting member for frictionally holding the arm in adjustment. Further objects and advantages of my invention will appear from the detail description.

In the drawing:

Figure 1 is a semi-diagrammatic fragmentary plan View of a, known type of electrical measuring instrument embodying the frictional holding means of my invention;

Figure 2 is a vertical sectional view through the instrument of Figure 1, certain parts being shown in elevation, and the instrument casing being shown fragmentarily and in section;

FigureB is a plan view of the bridge member of the instrument of Figures 1 and 2, on an enlarged scale;v f

Figure 4 is a fragmentary sectional View taken substantially on line 4-4 of Figure 3;

Figure 5 is a sectional view taken substantially on. line 5 5 of Figure 3, butV showing the adjustable arm and associated parts;

Figure 6 is a-view similar to Figure 3, but showingl a modified form of bridging member;

Figure 7A is a sectional View taken substantially on line 'I--l of Figure l;

Figure 8 is a fragmentary side View of a knife switch embodying the frictional holding means of my invention; and

Figure 9 is a sectional view taken substantially on line 9-9:of Figure y8.

,-In Figures 1, 2 and 5, I have illustrated the frictional holding means of my invention as applied to an electrical measuring instrument of known type, such as a volt meter or an electrical pyrometer. These instruments are well known, and a brief description of the portions of the instrument shown will sufce. This instrument comprises pole pieces I0 secured to and extending toward each other from thev pole ends of a permanent magnet (not shown) the opposed faces of the pole pieces I0 being provided with arcuate recesses I I which receive a movable coil I2. This coil I2 isv mounted on a suitable frame to which are-secured upper and lower arbors I3 and I II, respectively. The lower arbor I4 is pointed at its lower end and is there mounted, preferably in a jewel bearing, in the upper end`r of a screw I5v threaded through a lower bridge member I6, formed of copper or other suitable non-magnetic metal, suitably mounted on the pole pieces I 0 and bridging the gap therebetween. A jam nut I1 is threadedv on screw I5 atthe lower face of bridge memberlli and cooperates with the latter for locking screw I5 in adjustment. An attaching clip I 8 of substantially L shape is secured on bridge member I 6 and projects upward therefrom, the upwardly extending arm of clip I8 having secured thereto, by soldering or otherwise, one end of a torsion spring I9 extending spirally about arbor I4, secured at its other end to the downwardly extending arm of a clip 20 secured to arbor I4, conveniently by being clamped between two nuts 2i screwed on arbor I4, or in any other suitable manner. The upper arbor I3 is pointed at its upper end and is there pivoted in the lower end of a mounting screw 23, preferably in a jewel bearing member carried by this screw, threaded through an upper bridge member 24. An adjusting arm 25 is conned between the upper face of. bridge member 24 and a nut 25 screwing on the screw 23 and having a hub, as will be explained more fully presently, contacting bridge member 24 for securing screw 23 in adjustment. Arm 25 is provided, at one end thereoi, with a downwardly extending nger 21 to which is secured one end of a torsion spring 28 wound spirally about arbor I3 in opposite re-A lation for torsion spring I9, the other end of torsion spring 28 being secured to the upwardly extending arm of an L-shaped clip 35 secured on arbor i3. Conveniently, clip 30 is clamped between an upper nut 3l screwing on arbor I3 and an indicator arm 32 mounted on arbor I3 and secured thereto by being clamped, together with clip 35, between nut 3 lV and a lower nut 33 screwed on arbor i3. `The indicator arm or pointer 32 is appropriately shaped and disposed to move over a dial4 (not shown) of the instrument, and is provided with a balancing arm 34 weighted in a suitable` manner, as by a drop of solder deposited thereon. It will be understood that the clipsIS and 25., and the clip 30, and the pointer 32 may be mounted and secured in any suitable known manner other than that disclosed. Arm 25 projectsV outward beyond the upper bridge member 24 at the opposite side thereof from nnger 21, and is provided with an elongated slot 35. This slot 36 receives a pin 31 secured in an` adjusting arm 38, at one end thereof, arm 38 being secured at its other end to a nut 39, conveniently by soldering, which isthreaded on the inner end of va screw 4I passing through an opening in top Wall 42 of the instrument casing, there being a ber washer 43 interposed between arm 33 and wall 42. Nut 39 is fixed to screw 4I in a suitable manner, conveniently by being soldered thereto at 44, armi. 3S being soldered` to nut 349-, as noted, at 45.

The instrument so far described is of known construction and operation, it being understood that the upperA bridge member and the lower bridge member and parts associated therewith are formed of non-magnetic metal, as is usual. In the known instruments of this character, the adjustable arm 25 is frictionally held in adjustment by the action of a spring washer f known type, above referred to, and adjustment of arm 25Y is effected by turning'screw 4r in appropriate directions. It willbe noted that the torsionsprings I9 and 28 act in opposition, with the coil I2- mounted` by needle point bearings for rotation about a vertical'axis, and that the torsion spring 2 8 tends to turn arm 25 about the screw 23. 'Ihe frictionof the spring washer, in known instruments, suces to hold arm 25 in adjustment so that, by proper adjustment of arm 25 by means of screw 4| and the parts associated therewith, the instrument can be adjusted so that thepointer 32 thereof is at the Zero position of the dial when the coil I2 is deenergized.

The upper bridge member 24 is ofconsiderable thicknessand-is formed ofv spring copper or other` suitable non-magnetic metal; This bridge member 24.is mounted adjacenteachend on abrass block 41 provided, at its-lower end, with a-reduced central hub element 55a.

screw stud 48 threaded into the associated pole piece IU. Block 41 is suitably bored and tapped from its upper end, for reception of a securing screw 49 passing through bridge member 24 and threading into block 41, there being a washer 5B interposed between the head of screw 49 and bridge member24. Referring more particularly to Figures l and 3, bridge member 24 is of approximately oblong shape and is provided, at opposite sides of its longitudinal axis, with lengthwise slots 52 from which extend, at the inner ends thereof, outwardly inclined slots 53, providing two pairs of resilient fingers 54 disposed at opposite sides of the transverse axis of bridge 24, and a central hub element 55 from which extend strips 55, the latter and fingers 54 being integrally connected at their outer ends to the bridge 24. The inner ends of the fingers .54 are free from` hub. element 55, those of one pair of the fingers 54 being disposed at the opposite side 0f element 55 to those of the other pair of ngers, and the terminalpportions of ngers 54 being formed at 58 fonsubstantially point contact with an overlying element of arm 25, as will appear presently. The ngers 54 are deflected upward relative to bridge 24, and the free terminal portions thereof are bent upward at an angle, as in Figure 4.

The nut 23 is pro-vided with a reduced inner hub 5.0 seating at its inner or lower end on hub element 55 of bridge 24,this nut 26 serving as a nut for locking the upper screw 23 in adjustment. Hub 550i nut 2S passes through hub 5i of the adjustable arm 25, it being noted that hub 6G of nut 25 is of slightly greater height than the thickness of hub 6I of arm 25, providing slight clearance, a few thousandths of an inch, between the upper face of hub element 55 of bridge member 24 and the-underfaceof hub 5I of arm 2,5, thereby providing slight vertical clearance for hub 6I. When nut 26 is turned tightly onto s:rew 23, the under face of head 62 thereof, which isiiat and projects radially outward beyond hub 55 a-V considerable extent, overlies hub 6I of arm 25, and also overlies-the inner free end portions of resilient ngers 54 of bridge member 24. These fingers possess considerable strength and hold hub 5I of arm 25 in pressure contact with the nat under face of the flange of headv 62 of nut 25, eiective'for holding-arm25ml adjustment about

hub

5,5. Inthat manner, theV resilient fingers 54 of the bridge member 24` provide means for holding adjustable arm25 inl adjustment, in conjunction with the head1h orrrlange of` nut 23', avoiding necessity for providing an additional spring element, Vsuch as -arspringwasher of known type, and rendering` possible reduction in the overallheight ofthe bridge: structure. Itwill be noted that; the fingers `5.4 contact hub 5 1 of. arm 25 at a plurality of points disposedk diametrically opposite` of hub 5I., vwhich guards against any tendency to tiltingY of this, hub. with possible binding thereof on hub 6.0;of nut 261 Inl'i'gure 6 I have shown amodiiiedv form of bridge member 24a,A this bridge. member being provided with elongated U-'shaped slots 52dy defining resilient lingers 5L4aiintegrally connected at their outer ends to the bridge member and with their inner ends spaced at opposite sides of a rFne fingers 54a are deflected upwardand havertheir inner terminal portions 58a bent Vupward at an anglefor contact with the hub BSI.- of arm-25. Inusing-this form of bridge member,4 when the nutlisturned tightly onto screw 23, the resilient-l fingers-54a ana/n4l 5 are forced downwardly and thereby placed under tension, in the same manner as the fingers 5d of the bridge 24 in Figures 1 toll, inclusive, are placed under tension when nut 26 is turned fully onto screw 23. In either case, the spring fingers hold hub 6l of adjustable arm 25 in pressure contact with the inner or under face of the flange of head 62 of nut 26, effective for maintaining arm 25 in adjustment in the manner above def scribed.

In Figures 8 and 9 I have shown a knife switch of known type embodying the frictional holding means of my invention. This switch comprises a mounting clip 65, bolted or otherwise suitably secured to an insulating base B. The clip 65 has two upwardly extending substantially

parallel arms

67 and 68 secured together in spaced apart relation by a pivot member, conveniently a rivet 69, headed at its ends. A switch arm or blade Ill is mounted between arms Gl and 68 on rivet 69 for pivotal mo-vement thereabout. The mounting clip 65 is formed of spring metal of high electrical conductivity, preferably spring copper, and arm E8 thereof has struck therefrom a plurality of fingers 'H which are deflected inwardly so as to bear upon one side of arm l?, the other side of this arm or blade l!) being in flatwise contact with the inner face of arm 6i oi' the clip 65 and having a considerable area of contact therewith. The fingers ll ino-lj switch arm or blade 1E in pressure contact with arm El of the clip, effective for maintaining blade iii in adjustment about the pivot member or rivet 69. The effective length of the rivet 69 is such as to maintain the fingers 'Il under proper tension, it being understood that in Figure 9 the distance between the

arms

67 and 68 of clips 65 and the inward defiection of the fingers ll have been exaggerated for clearness of illustration. By providing the arm 68 of clip 65 with the resilient lingers 7|, necessity for providing a separate spring washer, as is the present practice. is avoided, effecting a saving in material and saving in time in assembling the switch structure.

As has been indicated above, and will be understood by those skilled in this art, changes in construction and arrangement of parts of my invention may be resorted to without departing from the eld and scope thereof, and I intend to include all such variations, as fall within the scope of the appended claims, in this application in which the preferred forms only of my invention have been disclosed.

I claim:

1. In frictional holding means of the class described, in combination, a supporting member, a second member positioned in closely spaced relation to said supporting member, a pivot member supported by said supporting member, and an adjustable member mounted between said supporting member and said second member for turning movement on said pivot member to different angular positions, said supporting member being formed of spring metal and having struck therefrom inwardly deflected resilient fingers bearing on the adjacent face of said adjustable member and holding the opposite face of said adjustable member in pressure contact with said second member effective to hold said adjustable member in adjustment on said pivot member.

2. In frictional holding means of the class described, in combination, a supporting member, a pivot screw in threaded engagement with said supporting member, a nut threaded on said screw into closely spaced relation to said supporting member, and an adjustable member mounted between said supporting member and said nut for turning movement to different angular positions aboutL the axis of said screw, said supporting member being formed of spring metal and having struck therefrom inwardly deflected resilient fingers bearing on the adjacent face of said adjustable member and holding the opposite face of said adjustable member in pressure contact with said nut effective to hold said adjustable member in adjustment on said pivot.

3. In frictional holding means of the character described, a fixed bridge member of spring metal, a nut secured to said bridge member having an inner reduced hub and an outer flange projecting radially outward beyond said hub having a flat inner face, and an adjustable arm having a hub rotatably mounted on the hub of said nut, said bridge member having integral resilient fingers bearing on the inner face of the hub of said arm maintaining the outer face thereof in pressure contact with the inner face of said. flange effective for holding said arm frictionally in adjustment about the hub of said nut.

4. In frictional holding means of the character described, e, fixed bridge member of spring metal, a, nut secured to said bridge member having an inner reduced hub and an outer flange projecting radially outward beyond said hub having a fiat inner face, and an adjustable arm having a hub rotatably mounted on the hub of said nut, said bridge member having integral resilient fingers bearing on the inner face of the hub of said arm at diametrically opposite points thereof maintaining the outer face of the hub of said arm in pressure contact with the inner face of said flange effective for holding said arm frictionally in adjustment about the hub of said nut.

5. In frictional holding means of the character described, a xed bridge member of spring metal, Ia nut secured to said bridge member having an inner reduced hub and an outer flange projecting radially outward beyond said hub having a at inner face, and an adjustable arm having a hub rotatably mounted on the hub of said nut, the latter hub being of slightly greater height than the thickness of the hub of said arm providing slight vertical clearance therefor, said bridge member being slotted thereby providing resilient fingers integral therewith, said fingers being deflected toward the flange of said nut and bearing on the inner face of the hub of said arm maintaining the outer face thereof in pressure contact with the inner face of said flange effective for holding said arm frictionally in adjustment about the hub of said nut.

6. In frictional holding means of the character described, a fixed bridge member of spring metal, a nut secured to said bridge member having an inner reduced hub and an outer flange projecting radially outward beyond said hub having a fiat inner face, and an adjustable arm having a hub rotatably mounted on the hub of said nut, the latter hub being of slightly greater height than the thickness of the hub of said arm providing slight vertical clearance therefor, said bridge member being slotted thereby providing resilient fingers integral therewith at their outer ends and shaped at their inner ends for point contact with the hub of said arm, said flngers being deflected toward the flange of said nut and bearing on the inner face of the hub of said arm maintaining the outer face thereof in pressure con- 7 tact with the inner face of said iiange effective for holding said arm friction'al-ly in adjustment about the hub of said nut.

'7. In a measuring instrument, a coil pivotedfor rotation about an axis, a fixed bridge member, a screw threaded through said bridge member providing a pivot for said coil, a nu'tsthread'ed on said screw locking it to said bridge member, said nut having an inner reduced hub seat-ing at its inner end on said bridge member and an outer flange projecting radially outward beyond said hub having a flat inner face, an adjustable arm having a hub rotatably mounted o n thev hub off said nut, the latter hub being of slightly greater height than the thickness of the hub of Said arm 'providing slight vertical clearance therefor, and a torsion spring anchored at one end to said coil andjat its other end to said arm tending to turn the latter about the hub of said nut, said bridge member being formed of spring metal and slotted thereby providing resilient iing'ers integral therewith at their outer endsI and free therefrom at their inner ends, said iingers being deflected toward the flange of said nut and bearing on the inner face of the hub of said arm maintaining the outer face thereof in pressure contact with the inner face of said Aflange eiective for holding said arm frictionally in adjustment about the hub of said nut.

8. In a lmeasuring instrument, a coil pivoted for rotation `about an axis, a fixed lbridgeA `member of spring metal slotted lengthwise at opposite sides of its longitudinal axis -to provide -a Acentral hub and two pairs of resilientvr fingers integral with said bridge member "at their outer ends having their inner ends free ffrom'sa'id bridge member with the inner ends of one pair of fingers Adisposed at `one side and ythe inner 4ends of the other pair of `iing'ers 'disposed at the Vopposite side of the transverse axis of said bridge member, a screw threaded through said hubproviding a pivot-for said coil. a nut ifhreaded on said screw "locking it `to the hub of said bridge member, said nut having-an inner reduced'hub seating-'at its inner 8 end on the 'hub of said bridge member and an outer iiange projecting radially outward beyond the hub of said nut having a iiat inner face, an adjustable arm having a hub rotatably mounted on the hub of said nut, the latter hub being of slightly greater height than the thickness of the hub of said arm providing slight vertical clearance therefor, and a torsion spring anchored at one end to said coil and at its other end to said arm tending to turn-the latter about the hub of said nut, said fingers being deflected toward the iiange of said nut and bearing on the inner face of the hub of said arm maintaining the outer face thereof in pressure contact with the inner face of said flange effective for holding said arm frictionally in adjustment about the hub of said nut.

9. In frictional holding means of the character described, a mounting clip having two substantially parallel supporting arms, a pivot member securing said arms together in spaced relation, and a member mounted between said arms on said pivot member for turning movement abo-ut the latter, said member having a flat surface of appreciable area in Contact with one of said arms, the other of said arms being formed of spring metal and having struck therefrom inwardly deflected resilient iingers bearing on the opposite face of said member and holding said flat surface thereof in pressure contact with said one arm eiiective for holding said member frictionally in adjustment about said pivot member.

10. In a devicey of the class described, in cornbination, a pair of adjacent members, a pivot supported by at least one of said members, and an adjustable member mounted between said adjacent members on said pivot for turning movement about the axis of the pivot, one of said adjacent members being formed of spring metal and having struck therefrom inwardly deflected resilient 'fingers adapted to bear on the adjacent face of the adjustable member to hold said adjustable member in angular adjustment.

JOHN A. OBERMAIER.