US2520509A - Resistor - Google Patents

Description

Aug. 29, 1950 H. F. PFEFFER ETAL RESISTOR Filed June 28, 1946 FIG.

FIG. 3

FIG. 2

INVENTOR. HERMAN F. PFEFFER CARL W. WAGENHALS ATTORN EY.

Patented Aug. 29, 1950 RESISTOR Herman F. Pfefier, Philadelphia, and Carl W. Wagenhals, Glenside, Pa., assignors, by mesne assignments, to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application june 28, 1946, Serial No. 679,968

' 9 Claims. (01. 201-56) The present invention relates to resistance units and more particularly to a small resistance unit or spool that may be easily and inexpensively manufactured in large quantities.

The resistance elements of the present invention are intended primarily as calibrating re-. sistances to be used in precisionelectrical instruments, although they are sturdy enough to be used in many other places. In resistances heretofore used for this purpose the main item of expense in their manufacture was the labor required to fasten the terminals to the spool itself. The construction of the resistance requires that the terminals be inserted by hand, and the'use of the resistance, which is usually mounted by its terminals, requires that they be rigidly fastened in place.

The present invention has for an object the production of a resistance element in which the terminals are rigidly held in place and one in which the terminals may be easily and rapidly assembled.

It is a further object of the invention to provide a rigid, wound resistance unit in which the terminals are held in place in the core partly by the core and partly by a separate plug element.

The various features of novelty which characterize our invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, however, its advantages and specific objects obtained with its use, reference should be had to the accompanying drawings and descriptive matter in which are illustrated and described preferred embodiments of the invention.

In the drawings:

Figure 1 is a sectional view of a resistance showing one manner of fastening the terminals in place.

Figure 2 is an end view looking from the right of Figure 1; and

Figure 3 is a sectional view of a resistance having the terminals attached thereto in a different manner.

Referring to Figure 1 of the drawingrit will be seen that there is provided a core I upon which a resistance winding 2 is placed. This core is preferably made of fibreglass although it may be made of any other suitable material that is rigid enough to. support the resistance winding. If the core is made of fibre glass it is cut to length from a tube of that material and impregnated with a suitable insulating material and baked so that it will retain its shape. The winding 2 is then placed upon the core I by any suitable type of winding machine. Leads 3 and 4 extending from the ends of the resistance winding are attached to'the terminals 5 and 6, preferably by twisting the ends of these leads around the ends of the terminals and soldering the leads to the terminals as is shown at 8 in the drawing. Terminals 5 and 6 are made of a heavier wire that has the strength to support the resistance element when these terminals are fastened to some mounting means. It has heretofore been extremely difficult to fasten rigidly the terminals to a resistance of this type in a simple manner so that the assembly is rigid enough to be supported by them. By means of the present invention the terminals may be rigidly fastened to the core in an inexpensive and simple manner. This is done with a minimum of hand labor. The ends of the terminals are bent as is shown in the drawing and forced through openings I in the core. This is preferably done before the leads 3 and 4 from the resistance winding are attached to the terminals. After the leads from the resistance winding have been soldered to the ends of the terminals, as shown at 8, these ends are bent into close engagement with the outer surface of core I so that the unit will not have any projections extending from its surface.

The free ends of the terminals 5 and 6 are held in place against the inner surface of the core by means of a suitable ceramic plug 9 placed in its end. As is shown this plug is formed at its right end with a slight taper so that it may easily be forced into the end of the core. Referring to Figure 2 it will be seen that the plug is provided with grooves In which receive the terminal wires 5 and 6 and hold the ends of the terminals rigidly in place against the inner surface of the core.

, While it is not generally necessary, it is some times desirable to place a second ceramic member II in the core at its opposite or right end in order to hold the terminal wires tightly against the interior of the core just behind the openings I where they project through the same. This is particularly true when terminals 5 and 6 are so assembled that one of them projects from each end of the core. After the resistance assembly has been made it may be dipped in some suitable insulating material and baked so that the entire assembly is protected from the effects of moisture or from rough usage.

- It will be seenthat the construction shown in Figure 1 of the drawing may easily be assembled. It is merely necessary to form an opening in the core for each of the terminal wires and to place the wires through these openings by hand. This is a relatively simple process and may be easily performed. The ceramic plugs 9 and II can be forced into the ends of the core I by a simple operation. Thus after a resistance has been wound the attaching of the terminals consumes a minimum amount of time and labor. The terminals, furthermore, are attached to the resistance unit rigidly enough so that they can be used to sup-. port the unit when it is later mounted in an electrical circuit.

Another way of mounting the terminals in the core unit is shown in Figure 3. In this instance the resistance assembly is exactly the same as that disclosed in Figures 1 and 2 except that the right ends of the terminals 5 and 6 are bent back upon themselves as shown at I2 in the drawing, instead of being forced through openings in the core I Preferably the ends of the terminals would not lie flush against the outer surface of the core until after the leads from the resistance wires had been attached thereto. When this is done the terminals will be bent to the shape shown. In this case also the left ends of the terminals are held in engagement with th inner surface of the core by means of a ceramic plug 9 that is provided with grooves ill through which the terminal wires extend. It is noted that the unit may be so assembled that one terminal is bent over each end of the core and projects from the opposite end.

In this embodiment of the invention a secondplug Ii may also be used in the right end of the core i to hold the terminal wires in place. As was stated in connection with Figure 1. the use of the plug in the right end of the core is not necessary, although in some cases it may be used to give added rigidity to the assembly.

From the above description it will be seen that we have made a resistance element in which the terminals may b easily and rigidly fastened to the core itself with a minimum of labor and in a minimum of time.

While, in accordance with the provisions of the statutes, we have illustrated and described the best forms of our invention now known to us. it will be apparent to those skilled in the art that certain changes may be made in the form of the apparatus disclosed without departing from the spirit of our invention as set forth in the appended claims, and that certain features of our invention may sometimes be used to advantage without a corresponding use of other features.

Having now described our invention, what we claim as new and desire to secure by Letters Patent is:

1. An electrical resistance element comprising a flexible tubular core, a resistance winding on said core having two ends, a protective material with which said core is impregnated and which is applied to said winding to provide protection for the latter, a pair of terminals, each attached to a respective one of said ends of said winding, each of said terminals being located within said core with one end extending through an opening in said core to the exterior thereof, said end of each terminal being the one that is attached to said winding, and means to hold said terminals rigidly in position against the interior of said core.

2. An electrical resistance element comprising a flexible tubular core, a resistance winding on said core having two ends, a protective material with which said winding and said core are impregnated, a pair of terminals, each attached to a respective one of said ends of said winding, each of said terminals being located within said core with one end extending through an opening in said core to the exterior thereof, said end of each terminal being the one that is attached to said winding, and means to hold said terminals rigidly in position against the interior of said core, said last mentioned means comprising a single plug forced into one end of said core to hold both of said terminals rigidly in position against the interior of said core.

3. An electrical resistance element comprising a flexible tubular core, a resistance winding on said core having two ends, a protective material with which said winding and said core are impregnated, a pair of terminals, each attached to a respective one of said ends of said winding, each of said terminals being located within said core with one end extending through an opening in said cor to the exterior thereof, said end of each terminal being the one that is attached to said winding, and means to hold said terminals rigidly in position against the interior of said core, said last mentioned means comprising a single plug forced into one end of said core and having grooves through which said terminals extend, whereby said plug holds both of said terminals rigidly against the interior of said core.

4. A resistance element comprising a flexible hollow core of tubular form, a resistance winding wound on the exterior of said core and having two ends, a pair of terminals, each attached to arespective one of said ends of said winding, each of said terminals having a portion located inside said hollow core and having an end extending through an opening in said core to the exterior thereof, said end of each terminal being the one that is attached to said winding, and a single plug forced into one of the open ends of said hollow core and provided with grooves through which said terminals extend, said plug having an outside diameter substantially equal to the inside diameter of said hollow core, whereby said plug holds both of said terminals rigidly against the interior of said core.

5. A resistance element as specified in claim 4, wherein said core is of fibre glass.

6. A resistance element as specified in claim 4, wherein said plug is of ceramic material.

7. A resistance element comprising a flexible hollow core of tubular form, a resistance winding wound on the exterior of said core and having two ends, a pair Of terminals, each attached to a respective one of said ends of said winding, each of said terminals having a portion located inside said hollow core and having an end extending through an opening in said core to the exterior thereof, said end of each terminal being the one that is attached to said winding, a single plug forced into one of the open ends of said hollow core, and a second plug forced into the remaining open end of said hollow core, both of said plugs being provided with grooves through which said terminals extend and each having an outside diameter substantially equal to the inside diameter of said hollow core. whereby each Number of said plugs holds both of said terminals rigidly 1 408 403 against the interior of said core. 1:525:831

8. A resistance element as specified in claim 7, I

REFERENCES CITED The following references are of record in the tile of this patent:

UNITED STATES PATENTS Name Date Ruehl et al. Feb. 28, 1922 Steiner et al. Feb. 10, 1925 Seaman Apr. 2, i946 Reiser Apr. 29, 1947 FOREIGN PATENTS Country Date Great Britain June 28. 1928

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