US 2682649 A
Description (OCR text may contain errors)
June 29, 1954 Filed Oct. 4, 1947 fig. 1.
l. s. BLONDER 2,682,649
ELECTRICAL CONNECTOR 3 Sheefcs-Sheet l v 4 v Caz/4N7 4 16 14 gi 5 figgr BY ATTORNEY I. S. BLONDER ELECTRICAL CONNECTOR June 29, 1954 5 Sheets-Sheet 2 Filed Oct. 4, 1947 INVENTOR. Isaac 6. Bimvder ATTORNEY June 29, 1954 BLONDER 2,682,649
ELECTRICAL CONNECTOR Filed Oct. 4, 1947 5 Sheets-Sheet 3 r W r. I. z s W E a m 1 Mu W mm B f c w 4 M a a S I A 5 ATTORNEY- Patented June 29, 1954 UNITED PATENT OFFICE 7 Claims.
The present invention relates to clamping mechanisms, and more particularly to mechanisms employed in electrical work, such as electrical connectors, clips, clamps and the like for gripping or clamping electrical conductors, such as wires, lugs, terminals, and tube-socket and other elements.
Present-day electrical devices of the abovedescribed character are of various types, but all are unsatisfactory.
The connectors known as alligator clips, for example, are subject to numerous disadvantages. In the first place, the meta1 teeth dig into, and thus remove pieces of, the clamp-ed work. This is particularly serious where the clamped work comprises a soldered junction. The difficulties attendant upon this type of connector increase with increase in size of the work to be clamped. This is because the larger the work the wider it is necessary to open the hinged jaws.
The alligator type of clip is subject to other disadvantages also. Since the teeth only of the jaws can make electrical contact with. the work, the area of contact is necessarily small, and, therefore, frequently faulty. For the same reason, the mechanical gripping provided by the teeth is frequently infirm. Very slight jarring of the clips, in normal use, consequently results in the clips often losing their hold upon the work. This, too, is a defect that becomes more troublesome on relatively large-sized work.
It is difficult, furthermore, with electrical connectors of this alligator type, to obtain a with ciently firm grip upon an electrical element that happens to be crowded near some other element. Even where the jaws of the clip do succeed in obtaining a grip, under these crowded conditions, moreover, the frequently short-circuit adjacent electrical connections. In using these clips, furthermore, the operator is often shocked, despite the presence of insulation that may be used to cover part of the clip. In order to prevent these effects, when it is desired to take a measurement of voltage or current, for example, it is generally necessary, therefore, to disconnect the vacuum-tube electrical equipment from its power source before attaching the connector to the part to be clamped; and it becomes necessary then to reconnect the electrical equipment to its power source, and to wait for the vacuum tubes to warm up again before the measurements can be taken. This, of course, is extremely timeconsuming and ineflicient.
It has accordingly been proposed to use clips of other types, such as spring-controlled loops of wire insertible about the electrical element to be connected into circuit by the connector. These other types of clips, however, are equally unreliable and disadvantageous, though for other reasons. They are particularly susceptible, for example, to slipping during the normal testing operations.
An object of the present invention, therefore, is to provide a new and improved electrical clip that shall not be subject to these disadvantages.
Another object i to provide a new and improved mechanism for clamping different-size work with equal efficiency.
A further object is to provide an electrical test clip that, besides providing reliable contacting area, shall have also unusual gripping and holding power.
Other and further objects will be explained hereinafter and will be particularly pointed out in the appended claims.
The invention will now be described more fully in connection with the accompanying drawings, in which Fig. l is a longitudinal section illustrating an embodiment of the electrical connector of the present invention; Fig. 2 is a fragmentary perspective, upon a larger scale, illustrating a piece of work clamped between the three coopcrating clamping members or jaws of the connector of the present invention; Fig. 3 is a longitudinal section taken along the line 33, of Fig. 1, upon a larger scale, showing more clearly the mechanical and electrical connection between a conductor and the opposite end of the stem carrying one of the jaws; Fig. 4 is a fragmentary longitudinal section similar to Fig. 1, upon a larger scale, of a modification according to which one of th clamping jaws is resilient, and illustrating the simultaneous clamping of different-size work; Fig. 5 is a diagrammatic perspective illustrating the electrical connector of the present invention clamping a piece of work for the purpose of making an electrical measurement; Fig. 6 is a section similar to Fig. 4, taken upon the line 6-6 of Fig. 5, looking in the direction of the arrows; Fig. '7 is a section taken upon the line l-l looking in the direction of the arrows shown in Fig. 6; Fig. 8 is a section taken on the line 8-8 of Fig. 6, looking in the direc-.
tion of the arrows; Fig, 9 is a view similar to Fig. 8 of a modification embodying a rectangular clamping wall; Fig. 10 is a longitudinal section similar to Fig. l of a modification; Fig. 11 is an underside plan of the connector shown in Fig, 1 or Fig. 10; Fig. 12 is a longitudinal section similar to Fig. 1 embodying the invention in preferred form; 13 is a perspective view of the eyelet used in the embodiment of Fig. 13; and Fig. 14 is a longitudinal section similar to Fig. 1, but embodying the construction of Fig. 12.
A tubular insulating handle 1 is shown in Fig. 1, provided with an axial longitudinally extending guiding recess 3 and a clamping jaw member 5 disposed at one end. The effective clamping surface of the clamping jaw 5 extends throughout the area of the said end of the handle. At the other end of the handle i, an insulating tubular member is slidably mounted in the axial recess 3. This tubular member comprises a longitudinally extending portion 7 terminally provided with a separate though integrally joined enlarged portion 26 interiorly threaded axially to form a recess El. The threaded recess 9 is intersected by a conductor-receiving recess H, disposed at an angle, preferably at right angles, thereto.
A conducting stem i3 is disposed in the axial recess 3, and extends into the tubular opening 2 of the tubular member I. The end of the conducting stem I3 adjacent to the tubular member 1 is threaded, as shown at I5, and is screwed into the axial recess 9. The conducting stem is is thus rendered threadedly adjustable into electrical engagement with a conductor :1 disposed in the conductor-receiving recess I I.
The recess I I is preferably provided with a depression I9, alined with the axially disposed recesses 3 and 2 and the threaded recess 9, and the said threaded end of the stem I3 is preferably provided with a pointed conducting terminal 2!. The conductor ll, moreover, is preferably covered with flexible insulation '23 of diameter slightly less than that of the cross-section of the conductor-receiving recess I I. The conducting stem I3 may, therefore, be adjusted threadably within the threaded recess 9 to cause the pointed conl ducting terminal 2| to penetrate the flexible insulation 23 of the conductor I'I, thereby establishing electrical contact with the conductor (1, as shown more particularly in Fig. 3. With further threaded adjustment, the conducting stem i3 will force the insulation 23 into wedging engagement with the walls of the depression is in the recess II, thus providing both excellent electrical contact and a rigid mechanical non-rotatable grip between the stem I3 and the conductor II.
Though this constitutes a feature of the preferred embodiment of the invention, other features are not limited thereto. A modified electrical and mechanical connection between a stem I3 and a conductor H is illustrated, for example, in Fig. 10. According to this modification, the free end of the conductor I1, bared of its insulation, is inserted through an enlargement 26' and the recess 2 of the tubular member I and is bent into a recess 28 having a function somewhat similar to that of the conductor-receiving recess II. The threaded end I5 of the stem I3 is now threaded into a recess 29 of the tube I. Adjustment of the threaded end I5 of the stem I3 within the recess 29 will effect the same result already described of clamping the conductor I1, thereby providing both an electrical and a mechanical connection.
Electrical connection between the test clip of Fig. 1 or Fig. and the conductor IT or IT is thus established within the insulating handle I, or preferably within the enlargement 26 or 26' of its insulating member 1, consequently eliminating any possibility of shocking the operator,
The other end of the conducting stem I3 or I3 extends through the handle I and beyond the clamping member 5, and is provided with a cooperating clamping member, jaw or spur 4 for cooperating with the handle clamping jaw 5. Since the stem I3 or I3 is conducting, provision is thus made for connecting the conductor I"! or H to the clamping jaw 4. The stem I3 or I3 extends beyond the jaw 4, terminating in a pointed terminal 30 which serves to displace adjacent electrical components from the particular component that is to be clamped, while the clamping jaw i is being inserted about the particular component. The terminal 38 serves a further function as an electrical prod for making point contact in testing.
A coiled spring 6 is disposed about the stem I3 within the handle I between the portion of the handle I that carries the clamping jaw 5 and the slidable tubular member I. The spring 5 biases the handle I and the tubular member I away from each other, and, therefore, the cooperating clamping jaws l and 5 toward each other. Relative movement toward each other of the handle I and the tubular member I, in opposition to the action of the coiled spring 5, which may be effected manually as illustrated, for example, in Fig. 5, will therefore permit separation of the cooperating jaws 4 and 5, in order to permit of clamping work therebetween.
In accordance with an important feature of the present invention, when a piece of work, such as a wire conductor 8, becomes thus clamped, an unusualy strong clamping action is produced. To the attainment of this end, the clamping jaw It is caused to incline from its outer end I0 toward the conducting stem I3, and a region A of the stem i3 is also caused to serve as a clamping jaw member. The inclining face of the jaw member 4 forces the work 3 against not only the jaw member 5, but also against the work-engaging region A of the jaw member i3, thus providing for a very rigid clamping action between these three jaw members 4, 5 and I3. The inclined nature of the inclining face of the jaw member 4 serves also a further purpose in that, within limits, work 8 of very different diameters will become rigidly clamped between these three jaw members 4, 5 and I3, as the spring 6 will automatically adjust the converging jaw 4 to effect this result. If the work is a cylindrical wire conductor and if the stem I3 is also cylindrical, this region A of engagement between the stem I3 and the conductor 8 will be constituted of a single point, as illustrated in Figs. 6 and 8. If the conducting stem is of rectangular cross-section, as shown at I2, in Fig. 9, however, the region A of engagement of the conducting stem I2 and the work 8 will be constituted of a single line of clamping engagement.
The region of engagement between the work 8 and the clamping jaw 5 is illustrated in Figs. 2, 6 and 7 at B. If the clamping jaw 5 is rigid and convex, the region B may also be constituted of a single point. As hereinafter stated, however, the region B need not be a single point though it should be a single region.
The clamping jaw 4 may incline toward the member I3 in any desired way. It is preferred, however, that the inclining be arcuate, as shown, as a very advantageous hooked clamping jaw 4 becomes thereby provided. The jaw 4 may be provided with two work-engaging regions, shown at C and D, Figs. 2 and '7. The regions 0 and D may be spaced along the jaw at any desired angle to the direction of relative adjustment of the jaws 4 and 5. Preferably, the spacing is at right angles to this direction, as illustrated. If the outer end IQ of the jaw A is pointed, the spacing of the work-engaging regions C and D will increase with increasing distances from the point It along the arc of the jaw 4.
The point it is very useful also as a prod in electrical testing, as it enables ready engagement of the work 8 in order that the work may slide i easily in between the jaws. No matter what may be the relative adjustment of the members 4 and 5 on a given piece of work 8, therefore, the jaw 4 will always provide work-engaging regions C and D on opposite sides of the plane through the axis of the stem I3 and the point Iii, illustrated as the plane E of Fig. 2. The direction of relative adjustment of the members a and 5 is parallel to this plane The plane of the regions A, C and D is at an angle to the plane E. The engaging regions A and B of the members l3 and 5, respectively, will naturally lie on this plane E. I
By reason of this construction, the two workengaging regions C and D, on opposite sides of the plane E, and the work-engaging regions A and B provide a firm four-region clamping contact which prevents the work from slipping out of clamping engagement. Tests have shown that it is necessary to exert a very large purposeful force, far greater than any force exerted in normal or in unusually careless use, to cause the work 8 to'slip out from this four-region clamping engagement, even to the slightest degree.
The tubular member I, into which the stem 43 is threaded, as before described, is rotatably, as well as slidably, mounted within the handle guiding recess 3. The hooked clamping jaw 4 may therefore cooperate with the handle-clamping jaw 5 at different areas thereof. It is for this reason that the handle-clamping jaw 5 is rendered effective to cooperate with the jaw 4 throughout its area, as before described. It therefore becomes unnecessary to deal with any problems of alinement of the jaws 4 and 5, as no such problems can arise.
If, for example, a voltage measurement across a network 22 is to be read on a meter 2d, the operator need merely push the insulating tubular member I relative to the insulated handle I, as illustrated in Fig. 5, to permit the conductor 8 to be inserted within the jaws 4, 5 and I3. Upon the release of the member 7, the spring 5 will cause the conductor 8 to become clamped tightly between the jaws 4, 5 and I3. A measurement may now be read on the meter 24. The electrical connector may then be removed, or replaced at another part of the circuit, while the voltages are still applied to the circuit, and without any danger of shocking the operator. Because the jaw 4, furthermore, is in the form of a hook, there is but little chance of short-circuiting adjacent electrical components during the measurements.
The handle-clamping jaw 5 may be made of any suitable material, but is preferably constituted of a cap of insulating material affixed over the end of the handle and the convexity of which corresponds to the concavity of the jaw It may be rigid or flexible. It is very desirable, indeed, that the jaw 5 be constituted of a resilient material, such as rubber, neoprene, and the like. In addition to being rigidly clamped, as heretofore described, the surface of the work engaged by the jaw 5 will then become depressed g the end 40 of the handle I.
into the resilient jaw, as illustrated in Fig. 4, thus providing an added frictional grip, in that the region B becomes thereby increased in area and depth. This is particularly advantageous in connection with the clamping of work of dilferent sizes, especially when it is desired to clamp work of different sizes simultaneously. This is illustrated by the small conductor I4 and the larger conductor I6, shown in Fig. 4; these conductors may both be simultaneously clamped rigidly. The resilient jaw 5 will become depressed in clamping the conductor I 4 to an extent illustrated at 29, while the larger conductor I6 will depress the jaw to a greater degree, as shown at I8.
It is not necessary that the handle clamping jaw 5 be supported directly upon an integral portion of the handle I. It is particularly advantageous, indeed, for purposes of manufacture, for example, to construct the clamping-jaw end of a modified insulating handle I according to the preferred embodiment illustrated in Figs. 12 and 14. A portion of the inner walls of the guiding recess 3' of the handle I' may be threaded or otherwise roughened, for a purpose hereinafter explained, at 36, near the end 49 of the handle I. One end of a hollow cylindrical eyelet member 34, preferably constructed of metal tubing such as, for example, of brass, and of diameter preferably slightly larger than the diameter of the stem I3, may then be inserted within the guiding recess 3', the other end of the eyelet member extending beyond the end 46 of the handle I'. The eyelet 34 may be provided with a flange 42 positioned near the inner end of the threaded portion 36. A plug of material 32, pref erably molten plastic, though any glue or similar substance may be used, may then be inserted within the space between the eyelet 34 and the threaded portion 36 to provide a secure joint between the eyelet 34 and the threaded wall at of the guiding recess 3. The jaw 5, preferably of resilient material, as above-mentioned, may then fit about the extension of the eyelet 3d beyond The jaw 5 is thus provided with the metal bearing surface of the eyelet 34, which serves to reduce the amount of friction created when the jaw 5 becomes depressed during the clamping operation.
Though the handle I or I and also the member I, with its enlargement 26 or 265', are each shown integral, they may, of course, for purposes of manufacture, be constructed of separate pieces. The position of the inclining and the other clamping members, again, may be interchanged. Further modifications, too, will occur to those skilled in the art, and all such are considered to fall within the spirit and scope of the invention, as defined in the appended claims.
What is claimed is:
1. A clamp comprising first and second cooperating clamping members normally held in contact with each other but relatively adjustable in order to separate the members and thereby to permit work to become clamped therebetween, an intermediate cooperating clamping member extending substantially in the direction of relative adjustment of the first and second clamping members, the first clamping member inclining with respect to the intermediate clamping member and being connected thereto providing for clamping different-size work between different portions of the first and intermediate clamping members in different positions of relative adjustment of the first and second clamping members, the second clamping member and the intermediate clamping member each being provided with only a single work-engaging region disposed in a plane substantially parallel to the said direction of relative adjustment, and the first clamping member being concave in transverse cross section to provide two work-engaging regions respectively disposed on opposite sides of the said plane, the width of the first clamping member progressively increasing as it inclines toward the intermediate member in order that the separation of the two work-engaging regions may correspondingly progressively increase.
2. An electrical connector comprising a tubular insulating handle provided at one end with a first clamping member and a longitudinally extending axial guiding recess, a conducting stem having near one end a second clamping member and slidably mounted within the axial guiding recess in order to provide relative adjustment between the first and second clamping members, thereby to permit work to become clamped therebetween, the second clamping member inclining with respect to the conducting stem near the said one end and providing for clamping different-size work between different portions of the second clamping member and the conducting stem near the said one end thereof in different positions of relative adjustment of the first and second clamping members, the first clamping member and the conducting stem being provided with only a single work-engaging region disposed in a plane substantially parallel to the direction of relative adjustment of the first and second clamping members, and the second clamping member being concave in transverse cross section to provide two work-engaging regions respectively disposed on opposite sides of the said plane, the width of the second clamping member progressively increasing as it inclines toward the conducting stem in order that the separation of the two work-engaging regions may correspondingly progressively increase.
3. A clamp comprising first and second coopcrating clamping members relatively adjustable in order to separate the members and thereby to permit work to become clamped therebetween, an intermediate cooperating clamping member extending substantially in the direction of relative adjustment of the first and second clamping members, the first clamping member inclining with respect to the intermediate clamping member and being connected thereto providing for clamping difierent-size work between different portions of the first and intermediate clamping members in different positions of relative adjustment of the first and second clamping members, the second clamping member and the intermediate clamping member each being provided with only a single work-engaging region disposed in a plane substantially parallel to the said direction of relative adjustment, and the first clamping member being concave in transverse cross section to provide two work-engaging regions respectively disposed on opposite sides of the said plane, the width of the first clamping member progressively increasing as it inclines toward the intermediate member in order that the separation of the two work-engaging regions may correspondingly progressively increase.
4. A clamp as claimed in claim 1 and in which the second clamping member is convex to correspond to and cooperate with the concavity of the said first clamping member.
5. A clamp as claimed in claim 1 and in which the second clamping member is cap-shaped, the convexity of the cap corresponding to and cooperating with the concavity of the said first clamping member.
6. A clamp as claimed in claim 5 and in which the second clamping member is constituted of resilient material.
7. An electrical connector as claimed in claim 2 and in which the first clamping member comprises a resilient cap disposed about the said one end of the said insulating handle.
References Citcdin the file of this patent UNITED STATES PATENTS Number Name Date 698,218 Norden Apr. 22, 1902 714,144 Chapman Nov. 25, 1902 1,250,175 Hill et a1. Dec. 18, 1917 1,373,838 Scoppola Apr. 5, 1921 1,650,779 Williams Nov. 29, 1927 1,737,506 McCracken Nov. 26, 1929 1,833,835 Hieronymus Nov. 24, 1931 1,979,091 Alsaker et al. Oct. 30, 1934 2,071,002 Rudd Feb. 16, 1937 2,074,324 Brown Mar. 23, 1937 2,236,279 Von Hoorn Mar. 25, 1941 2,237,588 De Barbieri Apr. 8, 1941 2,438,350 Reichard Mar. 23, 1948 2,459,832 McKinley Jan. 25, 1949 2,478,994 White Aug. 16, 1949 2,516,657 Spendlove July 25, 1950 FOREIGN PATENTS Number Country Date 30,313 Great Britain Mar. 23, 1911 272,331 Great Britain June 16, 1927 553,869 Great Britain June 9, 1943