US3440382A - Contact assembly for electrical apparatus - Google Patents

Description

'A ril22, 1969 v P. SILVIUS 3,440,382

CONTACT ASSEMBLY FOR ELECTRICAL APPARATUS Filed Sept'. 29, 1967 United States Patent 3,440,382 CONTACT ASSEMBLY FOR ELECTRICAL APPARATUS Paul Silvius, Murraysville, Pa., assignor t0 Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Sept. 29, 1967, Ser. No. 671,689 Int. Cl. H01h 3/00, 9/00 U.S. Cl. 200166 7 Claims ABSTRACT OF THE DISCLOSURE A plurality of threaded electrical contact terminals are supported on a generally tubular housing formed from electrically insulating material and disposed to pass through a plurality of corresponding recesses in the housing which are each open at one of the axial ends of the housing. A reinforcing member is disposed in each recess to withstand the stresses which result when a nut is tightened on each contact terminal to secure the terminal to the associated housing.

Background of the invention Summary of the invention In accordance with the invention, a housing or support member formed from an "electrically insulating material includes a central tubular wall portion having a plurality of axially and angularly spaced recesses which are each openat one of the axial ends of the housing. A generally U-shaped reinforcing member is disposed in each recess and retained therein by improved means to take up or withstand the stresses which result when an elongated contact terminal is assembled in each recess and a nut is tightened on the contact terminal to apply the resulting stresses to the reinforcing member rather than to the associated housing.

It is therefore an object of this invention to provide an improved electrical contact assembly supported on an associated electrically insulating housing.

Brief description of the drawings Other objects of the invention will be apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a view, partly in side elevation and partly in section, of a rotary switch embodying the invention;

FIG. 2 is a view in section, taken along the line 11- 11 of FIG. 1;

FIG. 3 is an enlarged detail view showing a portion of the rotary switch of FIGS. 1 and 2; and

FIG. 4 is an enlarged exploded view, in perspective, of the portion of the rotary switch shown in FIG. 3.

Description of the preferred embodiments Referring now to the drawings and FIG. l in particular, the rotary switch structure shown therein comprises a mechanism housing 11, a dial plate assembly 12, a

3,440,382 Patented Apr. 22, 1969 stator housing or contact support member 13, and the spacing members 15 and 15' which are disposed at the opposite ends of the stator housing 13 and which may be disposed between successive stator housings where a plurality of stator housings are provided, as disclosed in greater detail in US. Patent 3,206,564 and the other patents previously mentioned for a rotary switch structure of the same general type as that shown in FIG. 1. A shaft 16 extends axially through the switch structure 10 and is rotatably disposed in a bearing 17 at one end of the switch structure 10 and in a similar bearing (not shown) near the other end of the switch structure 10. A handle 18 is removably attached or secured to one end of the shaft 16 and an end cover 19 is removably attached at the other end of the switch structure 10 opposite the handle 18. As best shown in FIG. 2 a rotor assembly 21 may be carried by the shaft 16 and be rotatable with the shaft 16. The switch structure 10 may be mounted on a switchboard panel 23 or other supporting structure by means of screws or bolts (not shown) which may extend through the dial plate assembly 12 disposed at one side of the panel 23 into the mechanism housing 11 disposed at the other side of the panel 23. The stator housing or contact support member 13 may be retained in axial alignment on the switch structure 10 by means of bolts (not shown) which extend axially from the mechanism housing 11 through the stator housing 13 and any additional stator housings where provided, as explained in detail in the patents previously mentioned. It will be understood that additional stator housings or contact sup port members may be provided by utilizing longer bolts and increasing the number of stator housings as required.

The stator housing 13, the spacing members 15, and the rotor 21 are preferably formed or molded from an electrically insulating material having excellent non-tracking arc and wear resistant characteristics, such as a glasspolyester material with an aluminum trihydrate filler. Thus, the parts of the switch structure 10 which are subject to wear have a relatively long life.

More specifically, the stator housing or contact sup port member 13, as shown in FIGS. 1 and 2, is generally cylindrical in configuration and includes a tubular central wall portion 13C having a central opening 13D which extends axially therethrough, as best shown in FIG. 4. The stator housing 13 also includes an insulating wall portion 13A which may be formed integrally with and project outwardly from the central wall portion intermediate the axial ends of the stator housing 13 and which extends substantially around the periphery of the stator housing 13. The insulating wall portion 13A lies generally in a plane which is disposed at substantially a right angle with respect to the axis of the stator housing 13, as shown in FIG. 1. The stator housing 13 also includes a plurality of angularly spaced insulating wall portions 13B which may be formed integrally with and project outwardly from the central wall portion 13C, as best shown in FIG. 4, with each of the wall portions 13B extending axially between the opposite ends of the stator housing 13 substantially parallel to the axis of the stator housing 13 and being disposed generally transversely with respect to the wall portion 13A to define a plurality of axially and angularly spaced generally rectangular compartments 102, as indicated in FIG. 1, which are separated from one another by the wall portions 13A and 13B to increase the electrically insulating creepage distance between the contact terminals which are disposed in the compartments 102, as will be explained hereinafter. In order to receive a plurality of contact terminals 37, as will be described hereinafter, the stator housing 13 also includes a plurality of axially and angularly spaced recesses 142 which are associated with the respective com- 3 partments 102, as best shown in FIG. 4. Each of the recesses 142 extends transversely through the central wall portion 13C of the stator housing 13 and includes a relatively wider portion 142B which is open to one of the axial ends of the stator housing 13 and a relatively narrower portion 142A adjacent to the wall portion 13A of the stator housing 13. A pair of laterally spaced axially extending grooves or recesses 132 are provided in the central wall portion 13C on the opposite sides of each of the narrower recess portions 142A intermediate the ends of the recess portion 142A at the opposite sides of the central wall portion 130 as shown in FIG. 4. In addition, a pair of laterally spaced recesses 154 and 156 may be provided at the outer end of the narrow recess portion 142A for a purpose which will be explained hereinafter.

As illustrated in FIGS. 1 and 2, twelve pairs of relatively stationary contact members 37 may be disposed in two rows around the periphery of the stator housing 13. The twelve pairs of contact members 37 are angularly or circumferentially spaced at 30 angles around the periphery of the stator housing 13. The two contact members 37 of each pair are spaced axially with respect to the stator housing 13. Each member 37 functions as both a terminal member and as a contact member. The member 37 has a head 38 which is enlarged in one plane to bridge the narrower recess portion 142A and to engage the central wall portion 13C of the stator housing 13 on the opposite sides of the narrower recess portion 142A, as best shown in FIG. 3. The head 38 may be beveled in a manner as shown in FIG. 4 and is engaged by a contact roller carried by a rotor, as will be described hereinafter. The members 37 are composed of a suitable electrically conducting material and the heads 38 of the members 37 may be silver plated if desired. As shown in FIG. 4, the end of each contact terminal 37 opposite the head 38 is threaded, as indicated at 37A.

Each contact member 37 is retained in the associated stator housing 13 by means of a nut 41 which is threaded onto the member 37 to engage a washer 42 which is preferably composed of a transparent material, which may be of the deformable plastic type. As shown in FIG. 3, each washer 42 is generally rectangular in configuration to substantially fill the associated compartment 102 to thereby assist in preventing rotation of the associated contact member 37 after the contact member has been assembled on the stator housing 13. The washer 42 enables a person to look through the opening or recess 142 to observe when the contact roller carried by the associated rotor is engaging a particular stationary contact member 37.

It is to be noted that when the nut 41 which is disposed on each contact member 37 is tightened down, the nut 41 is disposed in one of the compartments 102 and applies pressure or stress in a direction toward the head 38 of the associated contact member 37 through the washer 42. In order to take up the stresses which result when the nut 41 is tightened down on the associated contact member 37, a generally U-shaped reinforcing member 110 which is formed from a resilient metallic material having a greater mechanical strength in compression than the material from which the stator housing 13 is formed is disposed in each of the recesses 142, as best shown in FIG. 4. Each of the members 110 includes a pair of spaced sidewalls 122 and 126 which are interconnected by a bight portion 124. The sidewalls 122 and 126 of the member 110 include the offset tang or tab portions 112 and 113, respectively, which may be formed by lancing or cutting the respective sidewalls of the member 110. In addition, the member 110 includes a pair of laterally projecting flange portions 114 and 116 which may be formed integrally with the member 110 at one end of each of the sidewalls 122 and 126, respectivel Prior to the assembly of each contact member 37 into the associated recess 142, the reinforcing member 110 is assembled into the associated recess 142 with the bight portion 124 being inserted toward the back of the recess 142 and more specifically toward the back of the relatively narrower recess portion 142A with the tang portions 112 and 113 being pushed into the slots or recesses 131 and 132 at the opposite sides of the relatively narrower recess portion 142A until the tang portions 112 and 113 dig into or engage the central wall portion 13C of the stator housing 13 to thereby retain the reinforcing member in assembled relation with the stator housing 13. It is to be noted that the reinforcing member 110 is assembled into the associated recess 114 of the stator housing 13 with the flange portions 114 and 116 being disposed in generally nested relation with the associated recesses 154 and 156 provided in the central wall portion of the stator housing 13 so that the exposed surfaces of the flange portions 114 and 116 are substantially flush with the outer surface of the central wall portion 13C. It is also to be noted that the relatively wider recess portion 142B provided in the central wall portion 13C facilitates the assembly of the member 110 in the relatively narrower recess portion 142A and that the member 110 extends transversely in the associated recess portion 142A with respect to the central wall portion 13C and extends between the opposite ends of the recess portion 142A, as shown in FIG. 3. When each contact member 37 is assembled into the associated recess 142 in the stator housing 13 after the associated reinforcing member 110 has been assembled into the relatively narrower recess portion 142A of the corresponding recess, the nut 41 is tightened down on the associated washer 42 with the flange portions 114 and 116 serving to distribute the stress which results on the washer 42 and to substantially prevent any damage to the washer 42 during the assembly of the contact member 37 on the stator housing 13. It is important to note that the head 38 of each contact member 37 bears only against the lower end of the associated reinforcing member 110, as best shown in FIG. 3, and that the stress or pressure which results when the nut 41 is tightened on the threaded portion of each contact member 37 is applied only to the other end of the reinforcing member 110 to substantially eliminate any stress on the material from which the central wall portion 13C of the stator housing 13 is formed and any damage to the central wall portion 130 which might inadvertently result during the assembly of the contact members 37 on the stator housing 13. It is to be noted that the space between the sidewalls 122 and 126 of the member 110 is selected to fit the dimensions of the associated contact member 37 and that after the member 110 is assembled into the associated recess on the stator housing 13 with the sharp edges of the tang portions 112 and 113 engaging the surfaces of the central wall portion 13C along the slots or grooves 131 and 132, the member 110 is prevented from moving either axially with respect to the stator housing 13 or transversely with respect to the recess in which the member 110 is disposed by the engagement of the tang portions on the surfaces of the slots 131 and 132 respectively.

Depending upon the number of different operating positions desired in the rotary switch structure 10, the rotor assembly 21 may have four conact rotors '51 disposed at 90 angles, as indicated in FIGS. 1 and 2, or it may have a larger number of contact rotors with the angle between the rotors adjusted to suit the particular application. The rotor provided may be of a onepiece construction and comprise a hub 53 and a plurality of arms 54 formed integrally with the hub 53. Each contact rotor 51 is composed of a suitable electrically conductive material and is provided with two spaced integrally formed enlarged contact portions 55. Each contact rotor 51 is disposed in a slot 56 provided in each one of the arms 54 of the rotor. Each rotor 51 is biased radially outwardly in the associated rotor by a spring 57 which is generally of a rectangular shape. A spring seat 58 is disposed between one end of the spring 57 and the associated rotor 51. A wheel 59 composed of electrically insulating material may be rotatably mounted on each end of the contact rotor 51 outside of the enlarged contact portions 55. The function of the wheels 59 is described in detail in the patents previously mentioned. The hub 53 of the rotor has a square opening 61 as shown in FIG. 2 for receiving the shaft 16. Thus the rotor assembly 21 rotates with the shaft 16.

In the overall operation of the rotary switch structure as illustrated, the contact rotors 51 on the rotor assembly 21 may be actuated between different angular positions by manually rotating the shaft 16 through the handle 18 to selectively bridge different pairs of contact terminals 37 electrically, as desired. Since each contact rotor 51 is rotatably mounted in an arm 54 of the rotor assembly 21, the friction between the contact portions 55 of each contact rotor 51 and the heads 38 of the stationary contact members 37 is reduced compared with the friction that might otherwise result between sliding contact members and the friction is reduced still further by the operation of the wheels 59, as explained in detail in the patents previously mentioned.

It is to be understood that in certain applications the flange portions 114 and 116 on each reinforcing member 110 may be omitted where the washers 42 are formed of a material having a sufficient mechanical strength to resist damage or severe deformation. It is also to be understood that in a particular application the contact assembly which comprises the stator housing 13v and the associated contact members 37 may be part of a relatively movable structure in a particular electrical apparatus.

The apparatus embodying the teachings of this invention has several advantages. For example, a contact assembly as disclosed including a plurality of threaded contact terminals which are secured to the associated electrically insulating support member or housing 13 by tightening down an associated fastening means, such as the nuts 41, is protected from damage to the insulating housing by the reinforcing members 110 during the assembly of the contact members 37 as disclosed which withstand substantially all of the mechanical stresses which result during the tightening of the nuts 41 on the associated threaded contact members 37 with each reinforcing member 110 being securely retained in assembled relation with the stator housing 13 as previously described. The disclosed arrangement for assembling the contact members 37 on the stator housing 13 also substantially prevents twisting or rotation of the terminal head 38 on each contact member during the assembly of the contact members 37 on the stator housing 13. A further advantage of the applicants disclosed construction is that the thickness of certain wall portions of the insulating housing may be decreased to permit a more compact construction of the overall electrical apparatus in which the invention is incorporated. Finally, where a transparent plastic washer 42 is provided to permit viewing of the interior of the contact assembly, the flange portions which may be provided on the reinforcing member 110 serve to distribute the stress on the Washer 42 to a greater degree and thereby prevent damage to the washer 42 that might otherwise result during the tightening of the nuts 41 on the threaded contact members 37.

Since numerous changes may be made in the above described apparatus and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all the matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Iclaim:

1. A contact assembly comprising a genenally cylindrical housing formed from an electrically insulating material, said housing including a tubular central wall portion having a plurality of axially and angularly spaced recesses extending transversely therethrough, each of said recesses being open at one end of said central wall portion and including a pair of axially extending grooves at the opposite sides thereof, a generally U-shaped reinforcing member formed from resilient, metallic material and disposed in each of said recesses in generally nested relation, said U-shaped member extending transversely between the opposite ends of the associated recess and including a pair of tang portions at the opposite sides thereof disposed in said grooves to engage the adjacent housing material to thereby retain said U-shaped member in assembled relation with said housing, and a plurality of elongated contact terminals formed of electrically conducting material and disposed to pass through the respective recesses, each terminal having an enlarged head at one end which bears against one end of said U-shaped member and a threaded portion at the other end on which a nut is disposed and tightened to thereby apply pressure only to the other end of the associated U-shaped member and to assist in retaining said terminal in assembled relation with said housing.

2. The combination as claimed in claim 1 wherein a washer formed from deformable plastic material is disposed between the nut and the U-shaped member associated with each contact terminal and each U-shaped member includes a pair of spaced laterally projecting flange portions at the end adjacent the nut on the associated contact terminal against which the associated washer bears.

3. The combination as claimed in claim 1 wherein the housing includes an outwardly projecting wall portion which extends substantially around the periphery of the central wall portion intermediate the axial ends of the housing and a plurality of axially extending, spaced portions projecting outwardly from said central wall portions transversely with respect to the first-mentioned outwardly projecting wall portion to form a plurality of generally rectangular electrically insulating compartments around the outer ends of the respective recesses.

4. The combination as claimed in claim 3 wherein a generally rectangular washer is disposed between the nut and the U-shaped member associated with each contact terminal to assist in preventing the rotation of the associated contact terminal in place after the associated nut is tightened.

5. A rotary switch comprising a generally cylindrical housing formed from an electrically insulating material, said housing including a tubular central portion having a plurality of axially and angularly spaced recesses extending transversely therethrough, each of said recesses being open at one end of said central wall portion and including -a pair of axially extending grooves at the opposite sides thereof, a generally U-shaped reinforcing member formed from resilient, metallic material and disposed in each of said recesses in generally nested relation, said U-shaped member extending transversely between the opposite ends of the associated recess and including a pair of tab portions at the opposite sides thereof disposed in said grooves, said tab portions being deformable to engage the adjacent housing material to thereby retain said U-shaped member in assembled relation with said housing, a plurality of elongated contact terminals formed of an electrically conducting material and disposed to pass through the respective recesses, each terminal having an enlarged head at one end which bears against one end of said U-sh-aped member and a threaded portion at the other end on which a nut is disposed and tightened to thereby apply pressure only to the other end of the associated U-shaped member and to assist in retaining the U-shaped member in assembled relation with said housing, and a rotor member having at least one movable contact disposed thereon rotatably mounted disposed to axially extend through at least part of said housing to thereby cause said movable contacts to engage and disengage said contact terminals.

6. The combination as claimed in claim 5 wherein a washer formed of a deformable plastic material is disposed between the nut and the U-shaped member associated with contact terminal and each U-shaped member includes a pair of spaced laterally projecting flange portions at the end adjacent the nut on the associated contact terminal against which the associated washer bears.

7. The combination as claimed in claim 6 wherein the central wall portion of the housing includes a pair of recesses adapted to receive the flange portions on each U-shaped member with the outer surface of each flange portion being substantially flush with the adjacent outer surface of the central wall portion.

References Cited UNITED STATES PATENTS 3,206,564 9/ 1965 Hauser. 3,213,255 10/1965 Kussy et al. 3,229,052 1/ 1966 Silvius et al. 3,229,051 1/1966 I-Iauser et al.

ROBERT K. SCHAEFER, Primary Examiner.

H. O. J ONES. Assistant Examiner.

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