Polarity Reversing Electrical Switch

A. Field of the Invention

The invention relates to electric switches and, more particularly, to polarity reversing electric switches.

B. Prior Art

Electric switches are used to interrupt power flow to a circuit, and to switch power from one portion of a circuit to another. Various characteristics of such switches, such as cost, size, reliability, and power handling capacity, among others, are dependent on the particular application for which the switches are used. The present invention is directed to low cost, mass produced switches with a moderate current capacity and used for applications such as energizing circuits, e.g., electric motor circuits, in automobiles and the like, and the prior art will thus be described with particular reference thereto.

Exemplary of the prior art in these applications are U.S. Pat. No. 3,671,693 issued June 20, 1972 to Guy M. Farrell; U.S. Pat. No. 3,746,809 issued July 17, 1973, to Martin Gaber; U.S. Pat. No. 3,601,568 issued Aug. 24, 1971 to Wesley T. Sorenson; U.S. Pat. No. 3,403,237 issued Sept. 24, 1968 to R. D. Wysong; and U.S. Pat. No. 3,519,775 issued July 7, 1970 to F. J. Weremey. These illustrate primarily single pole, double throw switches which utilize three terminals, namely, a common terminal and two switched terminals. As illustrated in the patent to Wysong, however, a pair of these switches may be utilized together to form a double pole, double throw switch; such a switch has six terminals, namely two common terminals and two pairs of switched terminals.

In forming a polarity reversing switch, the present practice is to utilize a double pole, double throw; six terminal configuration and wire alternate ones of the switched terminals together in the switch housing. This wiring or busing can constitute a significant part of the cost of manufacturing the switch, particularly where the switch is used in a large volume, low cost application such as the auto industry. Further, each additional element, such as a terminal, that is used in the switch increases not only the materials cost, but the cost of assembly as well and the latter element of cost is frequently a significant portion of the cost of manufacturing the switch. Thus, quantitatively small savings in materials or assembly, or both, can be significant in producing a more competitively priced switch.

Accordingly, it is an object of the invention to provide an improved electrical switch.

Further, it is an object of the invention to provide an improved polarity reversing switch.

Another object of the invention is to provide a polarity reversing switch which eliminates busing between switch terminals.

Yet another object of the invention is to provide a polarity reversing switch using only four terminals.

In accordance with the present invention, an improved polarity reversing switch has first and second terminal pairs for connection into a circuit which is to be switchably and reversably energized from an electrical source such as a battery. One of the terminal pairs comprises first and second terminals having an elongated shank extending through the housing for connection to a circuit at one end thereof exterior to the housing and terminating at the other end, interior to the housing, in a cradle-forming configuration. Preferably, the terminals are each identically formed from a single stamping, the cradles being formed from pairs of fingers bent outwardly from the face of the terminal at one end thereof and defining, between pairs of the fingers, bearing surfaces on which a rocker arm rests.

The second pair of terminals comprises third and fourth terminals, each comprising an elongated shank extending through the housing and terminating at one end thereof exterior to the housing for connection to an electrical circuit and terminating at the other end thereof, interior to the housing, in a pair of contact surfaces for engagement with a contact arm. These terminals also are preferably identical in configuration and formed from a single stamping of metal. The contact surfaces on the third and fourth terminals are so arranged on the terminals, and the terminals are so positioned in the housing, that a first contact surface of each terminal is positioned spaced from, and opposed to, a second contact surface of the other terminal. Thus, within the switch, the contact surfaces are arranged in pairs, each pair including a first contact surface of one terminal and a second contact surface of the other.

First and second contact arms, each in the form of an elongated beam connected to a rocker base, are mounted in the respective common terminal cradles and extend from the first and second terminals such that the remote end of each beam lies intermediate one of the opposed contact surface pairs formed by the third and fourth terminals. A rocker arm carries a spring loaded follower which engages the contact arms and urges them against one contact surface or the other of the respective pairs of contact surfaces, dependent on the position of the rocker. When the contact arms are moved from one contact surface to the other of each pair, the order in which the first and second terminals are connected to the third and fourth terminals is effectively reversed. Thus, if an electrical source of a given polarity is applied to either one of the terminal pairs, the polarity of the source observed at the other pair of contact arms is reversed as the contact arms are moved by the rocker from one position to the other.

The construction of the terminals, and their positioning within the switch housing, not only eliminates a pair of terminals, but also obviates the wiring or busing which would normally connect them to other terminals. This greatly facilitates the manufacturing and assembly operation, and thereby lowers the costs. This result is achieved with only two different terminal configurations, and this further contributes to cost savings.

The foregoing and other and further objects and features of the invention will be more readily understood when taken in conjunction with the accompanying drawings in which:

FIG. 1 is a pictorial view of one embodiment of a switch in accordance with the present invention;

FIG. 2 is an exploded view of the switch of FIG. 1 showing the interior components and their positioning within the switch housing;

FIGS. 3A, 3B and 3C are pictorial views illustrating preferred forms of terminals in accordance with the present invention;

FIG. 4 is a side sectional view of the switch of the invention taken along the lines 4--4 of FIG. 5;

FIG. 5 is an end sectional view of the switch taken along the lines 5--5 of FIG. 4;

FIGS. 6A and 6B are diagrammatic views showing the contact arms in opposed switching positions.

In FIG. 1, a polarity reversing switch 10 in accordance with the present invention includes a rocker arm 12 pivotally mounted by means of pins 14 in apertures 16 (see FIG. 2) extending through the opposite walls of a housing 18. The housing is preferably of a one piece molded plastic which is slightly deformable from side to side to accommodate insertion of the pins 14 therein. Recesses 20 (FIG. 2) in the inner side walls of the housing surrounding the apertures 16 provide guideways to facilitate insertion of the pins. Ears 22 extending from the end walls of the housing accommodate through-holes 24 to enable mounting the switch.

Referring now particularly to FIGS. 2, 4 and 5, a first pair of terminals 30, 30' and a second pair of terminals 32, 32' are mounted within the housing 18. Contact arms 34, 34' extend between the terminals 30, 30' and 32, 32'. Disposed above the terminals 30, 30' for engagement with the contact arms 34, 34' are followers 36, 36' having hollow interiors for receiving springs 38, 38' and seated in corresponding wells 40 (only one of which is shown in the drawings, the other being similarly located above the arm 34'). When the rocker arm 12 is rotated in one direction or the other about pins 14, the followers 36, 36' engage corresponding surfaces of the arms 34, 34' and pivot these arms into contact with opposed contact surfaces as will shortly be described in detail. A web 42 in the housing 18 limits rotation of the rocker 12 in the clockwise direction (as seen in FIG. 4) by engagement with a lower edge 12a of the rocker arm, and correspondingly limits rotation in the counterclockwise direction by engagement with a surface 12b of the rocker arm. This limits the force with which the arms 34, 34' contact the terminals 32, 32'.

Turning now to FIGS. 3A through 3C, the terminals 30, 32 and arm 34 are there shown in detail; the corresponding terminals 30', 32' and arm 34' are identical with the respective ones of these terminals and arms and therefore are not shown. In FIG. 3A, the terminal 32 has a broad faced shank portion 41 which extends outwardly of the housing (see FIG. 4) for connection to a circuit and which terminates at its upper end in first and second contact surfaces 44, 46, respectively. A connecting portion 48, comprising a horizontal portion 48a and a vertical portion 48b, interconnects the contact surfaces 44, 46. The upper portion of the terminal including the contact surfaces is thus configured in the form of a step, the surfaces 44 and 46 forming the lands of the step, and the vertical portion 48b of the connecting portion forming the rise of the step. A dimple 50, formed by partially punching through the surface of the shank 41, facilitates securing the terminal in the housing. Insert tabs 52, 54 provide wear surfaces for the terminals.

Similarly, the terminal 30 comprises an elongated, broad faced shank 60 extending through the housing 18 at the lower end thereof (FIG. 4) for connection into a circuit and terminating at the upper end thereof in a cradle 62 formed by first and second pairs of fingers 64, 66, respectively. The fingers of each pair are spaced apart from each other and define between them bearing surfaces 68, 70, respectively. The fingers and bearing surfaces rockably accommodate contact arm 34 (FIG. 3C) which comprises a thin, elongated beam 72 having a rocker base 74 extending outwardly from the sides thereof for mounting between the fingers 64, 66 of the terminal 30. That portion 76 of the arm adjacent the opposed sides of the base 74 is curved upwardly from the base so as to present a convex surface to the follower 36 (FIG. 4) when the switch elements are assembled. As the rocker arm 12 is rotated in one direction or the other, the follower 36 rides up on one part of the curved surface 76 or the other (see FIGS. 6A and 6B) respectively, and thereby rotates the contact arm in the cradle 62 into contact with opposed contact surfaces.

Referring back now to FIG. 2, the terminals 32, 32' are mounted parallel to each other and symmetrically within the housing. Thus, the first, or lower contact surface 44 of each terminal extends outwardly of the housing away from the other terminal, while the second, or upper contact surface 46 of each terminal extends inwardly toward the other terminal and overlaps the lower contact surface of the other terminal. The upper contact surface of each terminal is thus complementary to the lower contact surface of the other terminal; together, they form mixed pairs of contact surfaces which are directly opposite each other, each pair comprising an upper contact surface 46 of one terminal and a lower contact surface 44 of the other terminal.

In the present embodiment of the invention, the switch is configured as a double pole, double throw, polarity reversing, center-off switch. Thus, in the absence of a force applied to the rocker 12 by the user, the elements of the switch are positioned as shown in FIG. 4, with the followers 40 directly above the rocker base 74 and the contact arms 34 intermediate the upper and lower contact surfaces of the terminals 32, 32'. In this position, an open circuit is presented between the terminals 30, 30' and the terminals 32, 32'. When the user rotates the rocker 12 in the clockwise direction (as the switch is viewed in FIG. 4), the follower 36 rides on the forward sloping surface of the arm 34 and moves these arms into contact with the lower surfaces 44, 44' of the terminals 32, 32' (see FIG. 6A). In this position, the terminal 30 is electrically connected through contact arm 34 to the terminal 32 and the terminal 30' is connected through arm 34' to the terminal 32'. Conversely, when the rocker is rotated in a counterclockwise direction (as the switch is viewed in FIG. 4) the followers 36 ride upon the rearwardly sloping faces of the arms 34, 34' and thereby rotate these arms into contact with the upper surfaces of the terminals 32, 32', respectively. In this position, the terminal 30 is connected through contact arm 34 to the terminal 34', while the terminal 30' is connected through arm 34' to the terminal 32 (See FIG. 6B). Thus, if a source of fixed polarity is applied to either terminal pair, for example, the terminal pair 30, 30', the polarity of the source as observed at the terminals 32, 32', will be the same or reversed dependent on whether the rocker 12 is rotated in the clockwise direction.

From the foregoing, it will be seen that I have provided an improved polarity reversing switch. The switch is of relatively simple construction, utilizes four terminals instead of the six conventionally used, and eliminates internal wiring and busing that has heretofore been utilized to provide the polarity reversal function. It is simple and economical to construct and can be expected to have a wide variety of applications, particularly in the low cost, mass production market.

It is to be understood that various changes may be made in the invention described herein without departing from either the spirit or the scope thereof and that the foregoing specific description is to be taken as illustrative only and not in a limiting sense, the scope of the invention being described with particularity in the appended claims.