US 3031641 A
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Description (OCR text may contain errors)
April 1962 J. P. CAMZI 3,031,641
ELECTRIC CONTACT MEMBER Filed Oct. 14, 1958 (/0155 19404 @mwz/ ttes Electric contact members, generally constituted by a rigid male member coupled to a flexible female member or inversely, have the disadvantage of establishing contact, between the male and female members, along ridges represented as lines. As a result the points of contact between the said members are relatively few, thus, on the one hand, creating a resistance to the passage of the current and, on the other hand, causing but a light adherence of one member to the other; the said members thus risk becoming overheated and may separate under the action of light pulling. The contact member object of the invention, constituted by a hollow rod and divided into strips by longitudinal slots tends-to overcome the said disadvantages by the fact that the central part of the said rod which ensures the contact is cylindrical, thus establishing a sustained contact between the surfaces of the members adapted to be coupled one to the other and that the said central part has a cross section which differs from that of the ends which ensure the flexible action. There is thus produced a very eflicient contact by means of large surfaces; the electrical resistance is thus reduced and the adherence of the male members to the female members increased.
FIGS. 1 to 6 of the accompanying drawing shows, by way of example, two embodiments of the contact member, object of the invention. I
FIG. 1 is an outer view of a male contact member.
FIG. 2 shows the inside of the said member.
FIG. 3 is a view of the same in cross section, as also FIG. 4 which shows the male member coupled to a female contact member.
FIG. 5 is an outer view of a female contact member.
FIG. 6 is a longitudinal section thereof.
According to the first embodiment, the male contact member is constituted by a hollow rod 1 (FIG. 1) the central part 2 of which is a cylinder of a greater diameter than that of the end cylinders 3 and 4 situated on either side of the central cylinder 2. Longitudinal slots 5 are made in the cylinders which they divide into strips 6 which are connected one to the other by their extremities. The upper part 3 of the contact member the diameter of which is less than the bore of a female contact me.. her 8 (FIG. 4), penetrates easily into such a contact member, while the central part 2, of a greater diameter than the bore of the female contact member, only penetrates therein under the action of pressure which has for a result to bend the ends 3 and 4 of the strips 6. The elasticity of the said strips tends to maintain the diameter of the cylinder 2 at its original dimension, which causes the walls of the said cylinder to press against the inner walls of the female contact member 8 and consequently establishes an eflicient contact, the said contact occurring over the whole surface of the central cylinder 2. The ends 3 and 4 of the strips 6 have, over their whole length, parallel inner and outer surfaces, which constitutes a favourable shape for the elasticity of the said strips and for the permanent state of the said elasticity. in the case shown in FIG. 1, there are six slots, which thus constitute strips of small width thus having good elasticity and the shape of which is appreciably the same as that of parallel faced flat strips. It is obvious that a similar result could be obtained with a different number of slots 5.
In order effectively to produce a sustained contact of 3,031,641 Patented Apr. 24, 1962 the surfaces, the central cylindrical part 2 must not be a cylinder with a circular section; the strips 6, seen in section (FIG. 3), must have a curve the radius of which is equal to that of the female contact member, thus less than that of the enveloping circle 7, when the contact element is in the extension condition. When the strips contract, at the moment of penetration into the female contact member, the diameter of the central cylinder lessens to become equal to the bore of the female contact member 8. Since the strips 6 have a curve equal to that of the said contact member, contact occurs over the whole surface of the strips as shown in section in FIG. 4. The section shown in FIG. 3 may be obtained in a simple manner; the contact member which has, after machining on the lathe, a circular section, is passed through an edge tool having a bore equal to that of the female contact member 8; a rod of suitable diameter, inserted inside the contact member, limits the contracting of the strips to the amount necessary for the cutting spindle to remove the excess of material arising from the difference in the curves and thus gives the desired curve to the said strips.
To strengthen the elasticity of the strips 6, a flexible member pressing against the inner walls of the contact member may be inserted into the hollow part of the said member. FIG. 2 shows, inside the contact member, a flexible device of this kind. Flexible strips 9, in the shape of an open cylinder following a longitudinal slot, are inserted inside the cylinder 2 of the contact member and bear against the inner wall of the said cylinder. The action of the said strips 9 is to add their elasticity to that of the flexible strips 6 which on the one hand, may increase the pressure of the contact member against the inner walls of the female contact members and, on the other hand, reduce the possible strain on the said flexible strips. Since the strips 9 do not play any part from the point of view of conductibility, they may be of a material having a very high elasticity, without being a good conductor, such as steel. According to the required degree of elasticity, the necessary number of split flexible strips may be inserted inside the contact member.
FIGS. 5 and 6 show an outer view and a section of a female contact member. Such a member is adapted to receive a rigid male member constituted by a solid cylindrical rod; the pressure which establishes the contact is, in this case, ensured by the elasticity of the ends of the strips of the female member. The latter is constituted by a hollow rod and divided into strips by slots 10. The central part 11 has a smaller bore than that of the male contact member with which it must be coupled and the end parts 12 and 13 have a bore which exceeds that of the male contact member. The male contact member penetrates easily into the part 12, and then enters into the central part 11 by forcing the strips of the latter to separate, thus creating the necessary pressure. The surface of the male contact member is thus in contact with the whole surface of the central part of the female contact member, thus producing a very eflicient contact and strong adherence between the two members. The necessary cut to obtain the contact over the whole surface of the cylinder may be obtained by a spindle cutting method similar to the one provided for the male member. in the embodiment shown in FIGS. 5 and 6, the walls of the central cylindrical part are strengthened outside in thickness in order to increase their rigidity and leave the elastic action to the ends alone of the strips.
1. A female contact member machined in a piece of metal comprising a hollow rod having a continuous raised outer central part and two end members, said central part having a greater outer diameter than said end members, said central part having an inner continuous raised 3 portion with a diameter less than the inner diameter of said end member's, interior inclined surfaces with progressively decreasing diameters extending from the inner diameter of said end -members to the inner diameter of said central part, and longitudinal slots dividing said hollow rod into longitudinal flexible strips connected one to the other by their extremities, said strips showing in transve'rsal cross-section the general shape of ring sectors, said strips being strengthened at the central part in thickness to increase their rigidity thereby leaving elastic action to the end members.
2. A female contact member comprising a machined piece of metal in the form of a hollow rod having the end portions thereof consisting of the same outer diameter and substantially the same inner diameter, a continuous central portion having a greater outer diameter than that of said end portions and an inner diameter less than that of said end portions, the inner diameter of said end portions connected to the inner diameter of said central portion by progressively declining surfaces, one of the declining surfaces being longer than the other, and longitudinal slots disposed in said hollow rod equally dividing said rod into longitudinal flexible strips connected one to the other by their extremities in said end portions, said strips showing in transverse! cross-section the general shape of ring sectors whereby the central portion being of increased thickness increases the rigidity of said flexible strips and elastic action is effected by said end portions.
References Cited in the file of this patent UNITED STATES PATENTS 2,456,764 Bach et a1. Dec. 21, 1948 2,711,524 Beaver L June 21, 1955 2,724,096 Klosterrnann Nov. 15, 1955 FOREIGN PATENTS 258,622 Great Britain Feb. 24, 1927 403,864 Great Britain Ian. 4, 1934 739,472 Great Britain Oct. 26, 1955