US3436709A - Variable transformer having terminals held by core housing - Google Patents

Description

April 1, 1969 w. w. SCHAPIRA ET AL 3,436,709

VARIABLE TRANSFORMER HAVING TERMINALS HELD BY CORE HOUSING Filed May 22, 1967 wa /WI.

United States Patent 3,436,709 VARIABLE TRANSFORMER HAVING TERMINALS HELD BY CORE HOUSING William W. Schapira, Skokie, and Louis H. Berkelhamer,

Glencoe, Ill., assignors to Consolidated Electronics Industries Corp., Skokie, 11]., a corporation of Delaware Filed May 22, 1967, Ser. No. 640,194 Int. Cl. H01f 15/10 US. Cl. 336-192 6 Claims ABSTRACT OF THE DISCLOSURE Transformers are commonly made with a central core encased in a housing of plastic or other insulative material. The housing and core are at least partially enclosed by a spirally wound electrical coil. The coil is connected to metal terminals which are fixedly mounted on the housing by suitable connection means. A movable contact is usually connected to a terminal on the housing and is positioned for engagement with the coil to enable the output of the transformer to be varied. The terminals of these prior art transformers are in turn connected to electrical circuitry. A variable transformer constructed in the manner set forth above is disclosed in United States Patent No. 2,985,857 to Ellin et al.

Widespread usage of these prior art variable transformers clearly indicates that they are generally satisfactory in service. However, these prior art transformers are relatively difiicult and expensive to assemble. One assembly problem involves fixedly mounting the terminals on the core housing. The metal terminals must be connected to the plastic housing with sufficient rigidity so that the terminals do not loosen when they are connected to the coil and the movable contact during assembly. Of course, the terminals must also be fixedly connected on the housing with sufficient rigidity to enable associated or exterior circuitry to be connected to the transformer without loosening the terminals.

Therefore, it is an object of this invention to provide a variable transformer structure which overcomes the aforementioned limitations of prior art constructions. Specifically, it is an object of this invention to provide an inexpensive means for fixedly mounting terminals of a variable transformer on an insulative housing for a core of the transformer.

It is another object of this invention to provide a combination housing and terminal assembly having relatively few components.

These and other objects and features of the invention will become more apparent upon a consideration of the following detailed description taken in connection with the accompanying drawings wherein:

FIGURE 1 is an exploded perspective view of a transformer including a core housing upon which terminals are mounted in accordance with a preferred embodiment of the invention;

FIG. 2 is an exploded perspective view of the core housing and core of FIG. 1;

FIG. 3 is an enlarged perspective View, taken along the line 3-3 of FIG. 2, illustrating the structure of a terminal mounting section which is integrally formed with one section or element of the core housing of FIG. 2;

FIG. 4 is an enlarged sectional view, taken along the line 44 of FIG. 3, illustrating a cross sectional configuration of a set of mounting slots for holding terminals;

FIG. 5 is an enlarged plan view of the. mounting section of the housing structure illustrating the relationship of terminals positioned in mounting slots formed in the housing element;

FIG. 6 is an enlarged sectional plan view of a portion of the housing illustrating the relationship of a terminal to the slots in the mounting sections of the housing elements; and

FIG. 7 is an enlarged perspective view of a preferred embodiment of the terminals.

Referring now to the drawings in greater, a variable transformer unit or assembly 10 forming a preferred embodiment of the invention is shown exploded in FIG. 1 to illustrate the structure of the components of the transformer unit. The variable transformer unit 10 includes a core and winding assembly 12, a drive shaft and con tact arm assembly 14 and a dial and mounting plate assembly 16. The core and winding assembly 12 includes a spiral wound electrical winding 18 which is connected to metallic terminals 20. The terminals 20 are fixedly mounted on a mounting area 22 of an insulative core housing 24 which is formed of a phenolic plastic and is best seen in FIG. 2 taken in conjunction with FIG. 1. The insulative housing 24 includes a pair of substantially identical cup-shaped housing elements or sections 26 and 28 which encase an annular magnetic core 30. The mounting area 22 is formed by a pair of radially outwardly projecting mounting bosses or sections 32 and 34 which are integrally formed with the generally toroidal housing elements 26 and 28. The housing elements 26 and 28 are normally retained by the electrical winding 18 with open end face surfaces 38 and 40 in abutting engagement to position the mounting sections 32 and 34, as shown in FIG. 1, to form mounting area 22.

The drive shaft and contact arm assembly 14 includes a contact assembly 42 which is mounted on a central axially extending drive shaft 44. The contact assembly 42 includes a contact arm unit 48 upon which a movable or wiper contact 50 is mounted. When the transformer unit 10 is assembled, the wiper 50 engages the electrical winding 18 and is movable to vary the output of the transformer unit 10. Insulation is ground or otherwise abraded from the electrical winding 18 to form a track which can be plated in a well-known manner with rhodium or other suitable metal to improve electrical connections between the contact 50 and to improve wear resistance of the electrical winding 18 in the area or track where the contact 50 engages the winding.

The dial plate mounting assembly 16 includes a dial plate 54, having suitable indicia thereon, which is mounted on a backing or mounting plate 56 which is in turn fixedly connected to the housing assembly 24. A knob 58 is connected to the drive shaft 44 and includes a pointer section 60 which cooperates with the indicia on the dial plate 54 to indicate the position of the movable contact 50 relative to the electrical winding 18. The structure and functional interrelationship of the core and winding assembly 12, the drive shaft and contact arm assembly 14 and the dial mounting plate assembly 16 are well known to those skilled in the art. A preferred embodiment of these assemblies is set forth in application Ser. No. 456,- 978 filed on May 19, 1965 by Ellin for Variable Transformer with Winding Holding Core Housing, now issued as U.S. Patent No. 3,316,517. Those who are interested in the specific structure of these assemblies and their interrelationship are referred to this application.

The mounting sections 32 and 34 are substantially identical in structure. Therefore, only the structure of the mounting section 34 will be described in detail, it being understood that the mounting section 32 is substantially the same in structure as the mounting section 34. The mounting section 34 is shown in greater detail in FIGS. 3 and 4 and includes a plurality of parallel generally T- shaped terminal mounting slots or grooves 62, 64 and 66. The T-slots 62 through 66 have generally rectangular axially extending body sections 68, 70 and 72 which extend from open ends 76, 78 and 80 at the face wall 40 to transversely extending end surfaces or walls 84, 86 and 88. The T-slots 62 through 66 also include axially extending head sections 90, 92 and 94 (see FIG. 4) which are offset transversely relative to a central axis of the body sections 68 through 72. It should be noted that the head sections 90 and 94 are offset in a first direction, that is to the left, as viewed in FIG. 4, while the head section 92 is offset in a second direction, that is to the right as viewed in FIG. 4. The head sections 90, 92, 94, are positioned inwardly of the 'body sections 68 through 72 and are separated from the body sections by transversely projecting shoulders 96.

Referring now to FIG. taken in connection with FIG. 2, it can be seen that the mounting area 22 is formed by positioning the housing elements 26 and 28 with face surfaces 38 and 40 of the mounting sections 32 and 34 in abutting engagement. The mounting sections 32 and 34 are oriented so that the T-slots which are integrally formed with the mounting section have their open ends adjacent to each other and body sections in longitudinal or axial alignment. However, since the housing element 26 is rotated 180 relative to the position of the substantially identical housing element 28, the offset head sections of the T-slots are not in alignment.

This misalignment of the head sections of the T-slots is best seen in FIG. 5. The T-slots in the mounting section 32 have been designated in FIG. 5 with numerals similar to the numerals used in connection with the T- slots in the mounting section 34. However, the suflix letter a has been added to the numerical designation for the T-slots in the mounting section 32 in order to avoid confusion. The alignment of the mounting sections 32 and 34 results in the T-slot 62 in the mounting section 34 being opposite to T-slot 66a in the mounting section 32 while the T-slot 66 in the mounting section 34 is opposite to the T-slot 62a in the mounting section 32. The center T- slots 64 and 64a are in general alignment with each other. However, it should be noted that the head section 911 of the T-slot 62 is offset relative to the head section 94a of the T-slot 66a. Therefore, only the body sections of the T- slots 62 and 66a are aligned. From a further inspection of FIG. 5, it can be seen that the head section 92 of 4 the T-slot 64 is offset relative to the head section 92a of the T-slot 64a. Similarly, the head section 94 of the T- slot 66 is offset relative to the head section a of the T- slot 62a.

This offsetting interrelationship between the head sections of the T-slots is shown in greater detail in FIG. 6. From FIG. 6 it can be seen that a longitudinally extending transversely outer sidewall of the head section 90 is located outwardly of a longitudinally extending transversely outer side wall or surface 102 of the head section 94a of the T-slot 66a. This offset relationship of the side walls 100 and 102 provides a transversely extending positioning surface 186 which is engaged by a positioning tab or ear 108 of the terminal 20 which is mounted in the T-slot 62. The end wall 84 of the T-slot 62 is engaged by an oppositely extending positioning tab or ear 110 to fixedly locate the terminal 20 against longitudinal movement in the T-slot 62. If a terminal 20 was mounted in the T-slot 66a, the terminal would be oriented with the positioning ear or tab 110 in engagement with an end wall 88a of the T-slot 66a. The positioning ear or tab 108 would engage a positioning surface 112 formed by the offset between the head sections 90 and 94a at an outward or opposite end of the T-slot 66a. It should be noted that the terminal 20 engages the face surface 38 of the housing element 26 at the positioning surface or section 106 to fixedly retain or hold the terminal against longitudinal movement relative to the T-slot 62. Similarly, if the terminal 20 was mounted in the T-slot 66a, the terminal would engage the surface or offset shoulder 112 formed by the surface 40 at the open end of the housing element 28.

The structure of the terminal 20 is illustrated in greater detail in FIG. 7. The terminal 20 includes a base 114 from which the positioning ears or tabs 108 and 110 extend longitudinally outwardly.

When the terminals 20 are mounted in the slots in the mounting sections 32 and 34, they are retained against radially outward movement relative to the housing sections 26 and 28 by the shoulders 96 of the T-slots which engage the base section 114 of the terminals. A pair of connector sections 116 and 118 extend upwardly from the base 114. The connector section 116 includes a hole or aperture 122 to which a wire from apparatus associated with the variable transformer 10 can be soldered. The connector section 116 is also advantageously formed to receive slip-on type connectors to enable the transformer 10 to be connected to associated circuitry without the time-consuming process of soldering. The connector section 118 is soldered to leads extending from the electrical winding 18.

Turning once again to a consideration of FIG. 5, taken in conjunction with FIG. 6, a plurality of grooves or slots 126 and 128 are formed in the mounting area 22 for receiving wires or leads 130 which are connected to the terminals 20 and the coil 18. The grooves 126 and 128 are formed by recesses 132 (see FIGS. 3 and 6) which extend inwardly from the face surfaces 38 and 40 of the housing elements 26 and 28. The leads 130 extend through the grooves 126 and 128, which have a generally U-shaped cross section, into the body sections 68 and 72 of the T- slots 62 and 66. Since the leads 130 are positioned in the grooves 126 and 128 beneath the surfaces of the mounting sections 32 and 34, the leads are protected and positioned for connection to the terminals by the grooves.

In view of the foregoing remarks, it will be apparent to those skilled in the art that the housing assembly 24 is assembled by sliding terminals 20- into the slots 62 and 66 in mounting section 34 and sliding a third terminal 20 into the slot 64a of the mounting section 32. The terminals will be retained or held against longitudinal movement relative to the slots by the abutting engagement of the positioning tabs 108 and 110 with the face surface of the opposite or opposing housing element. Thus, the positioning tabs 108 of the terminals 20 mounted in the slots 62 and 66 engage the face surface 38 of the housing element 26 while the positioning tab 110 of the terminal 20 mounted in the slot 64a engages the base surface 40 of the housing element 28. This engagement between the terminals and the opposite housing element results from the transverse offset of the head sections of the T-slots. The terminals 20 will be retained against radially outward movement relative to the T-slots by the shoulders 96 which project over the base section 114 of the terminals 20. It should be noted that the mounting tabs 108 and 110 are positioned within the relatively large offset portion of the head sections 90 through 94 to enable the connector sections 116 and 118 of the terminals to extend upwardly through the body sections 68 through 72 of the T-slots. After the terminals 20 have been slid into position in the -slots, the electrical winding 18 is Wound around the housing to fixedly interconnect the housing sections 26 and 28 as shown in FIG. 1. The leads from the electrical winding 18 are then connected to the terminals 20. It should be noted that the connector sections 118 of the terminals 20 are maintained in a spaced apart relationship relative to each other by the positioning tabs 108 and 110 to facilitate connecting of the electrical winding to the terminals 20.

While particular embodiments of the invention have been shown, it should be understood, of course, that the invention is not limited thereto since many modifications may be made; and it is, therefore, contemplated to cover by the appended claims any such modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. A variable transformer comprising: an annular magnetic core; an electrical winding on said core; an electrically insulative housing between said core and said winding, said housing including first and second rigid housing elements, said housing also including a mounting section in which a plurality of slots is formed; and a plurality of terminal members slidably mounted in the slots, said terminal members being in abutting engagement With first surfaces of said first housing element and with second surfaces of said second housing element to fixedly position said terminal members in the slots, wherein the slots in said housing have a relatively narrow body section and a relatively wide head section located inwardly of the body section and wherein said terminal members include a relatively wide base section which is slidably received in the head section of the slot to retain the terminal members against outward movement relative to said housing.

2. A variable transformer as set forth in claim 1 wherein said slots are generally T-shaped in cross section.

3. A variable transformer as set forth in claim 1 and further including: a groove formed in said housing and extending transversely to and intersecting one of the slots in said housing; and a wire connected at a first end to said electrical winding and connected at a second end to a terminal member in the slot intersected by the groove, said wire being positioned in the groove beneath a plane of an outer surface of the mounting section.

4. A variable transformer comprising: an annular magnetic core; an electrical winding on said core; an electrically insulative housing between said core and said Winding, said housing including first and second rigid housing elements aligned with open end faces in abutting engagement to form an enclosure for said core; a first mounting section connected to said first housing element and at least partially defining a first longitudinally extending slot which includes a relatively narrow longitudinally extending body section intersecting the face surface of said first housing element and a relatively Wide longitudinally evtending head section which also intersects the face surface of said first housing element; a second mounting section connected to said second housing element and at least partially defining a second longitudinally extending slot which includes a relatively narrow longitudinally extending body Section which intersects the face surface of said second housing element and a relatively wide longitudinally extending head section which also intersects the face surface of said second housing element; first terminal means mounted in said first slot for connecting electrical circuitry to the variable transformer; said first terminal means engaging the face surface of said second housing element and a transversely extending end surface of said first slot to retain said first terminal means against longitudinal movement relative to said first mounting section, said first terminal means including a base section positioned in engagement with the head section of said first slot to retain said first terminal means against outward movement relative to said first mounting section; and second terminal means slidably mounted in said second slot for connecting electrical circuitry to the variable transformer, said second terminal means engaging the face surface of said first housing element and a transversely extending end surface of said second slot to retain said second terminal means against longitudinal movement relative to said second mounting section, said second terminal means including a base section positioned in engagement with head section of said second slot to retain said second terminal means against outward movement relative to said second mounting section.

5. A variable transformer assembly as set forth in claim 4 wherein: said first terminal means includes an upstanding connector section and a longitudinally extending positioning tab, said positioning tab of said first terminal means engaging the face surface of said housing element to space the upstanding connector section of said first terminal means apart from the face surface of said second housing element; and said second terminal means includes an upstanding connector section and a longitudinally extending positioning tab, said positioning tab of said second terminal means engaging the face surface of said first housing element to space the upstanding connector setcion of said second terminal means apart from the face surface of said first housing element.

6. A variable transformer comprising: an annular magnetic core; an electrically insulative housing between said core and said winding, said housing including first and second rigid housing elements aligned with open end face surfaces in abutting engagement to form an enclosure for said core; a first mounting section integrally formed with said first housing element and at least partially defining a first set of longitudinally extending slots, each slot of said first set of longitudinally extending slots including a relatively narrow longitudinally extending body section which intersects the face surface of said first housing element at an open end of the body section and a relatively wide longitudinally extending head section which intersects the face surface of said first housing element at an open end of the head section, the head section being located radially inwardly of said body section and offset transversely relative to said body section; a second mounting section integrally formed with said second housing element and at least partially defining a second set of longitudinally extending slots, each slot of said second set of longitudinally extending slots including a relatively narrow longitudinally extending body section which intersects the face surface of said second housing element at an open end of the body section and a relatively wide longitudinally extending head section which intersects the face surface of said second housing element at an open end of the head section, the open end of the body section of each slot of said second set of slots being positioned in alignment with the open end of the body section of said first set of slots, the head section of said first set of slots being located radially inwardly of and offset relative to the body section of said first set of slots, and the head section of said second set of slots being located radially inwardly of the body section of said second set of slots and offset relative to both the body sections of said second set of slots and the head section of said first set of slots; first terminal means mounted in a slot of said first set of slots for connecting electrical circuitry to the variable transformer, said first terminal means extending through the open end of the head section of a slot of said first set of slots to engage the face surface of said second housing element and hold said first terminal means against movement relative to said first housing element; and second terminal means mounted in a slot of said second set of slots for connecting electrical circuitry to the variable transformer, said second terminal means extending through the open end of the head section of a slot of said second set of slots to engage the face surface of said first housing element and hold said second terminal means UNITED STATES PATENTS 5/1965 Helberg 336-192 4/1967 Ellin 336149 LEWIS H. MYERS, Primary Examiner.

l0 THOMAS J. KOZMA, Assistant Examiner.

US. Cl. X.R. 336--l98, 149

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