Trailer breakaway switch assembly and pull-pin actuator therefor

FIELD OF THE INVENTION

Breakaway switch devices have long been used to detect the unintended separation of a pair of mutually coupled vehicles or other such machines, for example, the separation of a towed vehicle from a towing vehicle such as a trailer and an automotive vehicle pulling the trailer. Various different forms of such devices have been used or considered over time, but the most widely accepted type is one which uses a “pull-pin” or the like that is connected to the towing vehicle and normally carried in an inserted position in a switch housing mounted on the trailer, in which position the pin is disposed between a pair of electrical contacts located inside the housing, to prevent them from contacting one another and allowing current to flow through them. Since the pin is connected to the towing vehicle, the accidental decoupling of the towed vehicle will immediately pull the pin out of the switch housing, allowing the electrical contacts to touch and thereby complete an electrical circuit that can actuate an alarm and/or provide some other such desired result, including the application of brakes on the towed vehicle, as an automatic response.

BACKGROUND OF THE INVENTION

Many or most such breakaway switch devices used in the past have included electrical contacts that are either attached to or comprise an integral part of long, specially shaped blade-type electrically conductive members which not only carried the electrical contacts but also acted as springs. These were specially mounted and retained inside a switch housing so that their end extremities or other contact portions would normally be spring-biased into mutual contact were it not for the pull-pin actuator, which when inserted pushed the two self-biased spring contacts apart to prevent their engagement and thereby maintain the same in open-circuit configuration until the pin was withdrawn.

Switch assemblies of the type just described are expensive to produce since the long spring-type electrical contacts are relatively expensive to manufacture, and they are also difficult and labor-intensive to assemble within the switch housing, as they do not lend themselves to automated assembly and typically require manual assembly. Furthermore, they often do not provide optimal switching operation due to their size, shape, and manner of operation, and are often subject to exposure to the elements, since their corresponding switch housings may not be well sealed. Consequently, the switch contacts may rust and corrode over time, sometimes becoming unreliable and even inoperative at the time upon when they are finally needed. In addition, such spring-contacts may lose their resiliency over time and are also subject to distortion by bending in use, due to the insertion and withdrawal of the pull-pin actuator each time a trailer is coupled and uncoupled. Numerous other disadvantages also attended the use and manufacture of such switch assemblies.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a unique and effective solution for problems such as those noted above in connection with previous types of breakaway switches, providing a new type of breakaway switch assembly of high reliability and long life which is at the same time extremely economical to manufacture and also easy to use.

In a first aspect, the breakaway switch assembly comprises a housing enclosure having a self-contained switch unit disposed inside it which has an internal switch mechanism and an externally accessibly operating member. The self-contained switch unit has an outer body with mounting surfaces that engage switch-retention members inside the housing enclosure to hold the switch unit in predetermined placement therewithin. Input and output conductors are connected to corresponding terminals of the switch unit to carry an electrical current which is switched through the switch unit, such signal conductors extending out of the housing enclosure. An externally accessible actuator extends into the housing enclosure in alignment with the switch-operating member of the switch unit, and the actuator is movable from at least a first position to a second position whereby it moves the switch-operating member into and out of a position causing electrical conduction through the switch unit.

In a preferred embodiment, the self-contained switch unit to be mounted inside the housing enclosure comprises a standard off-the-shelf push-button or rocker-type switch, with integral flanges or the like which are rapidly and easily insertable into place between opposing such flanges provided inside the housing, and the switch unit includes spade-type or other such quick-connect electrical terminals extending from it, by which the electrical conductors used to form the related electrical circuit may be quickly and easily connected to the switch unit during manufacture. In addition, a preferred pull-pin actuator for the assembly comprises an integral one-piece member, preferably molded of non-conductive or other such polymer, to provide a very economically manufactured member of high reliability and easy utilization, and having a structural configuration which includes a portion for directly engaging the switch unit operator (push-button or rocker), to hold it in predetermined position actuating the switch in a desired manner dependent upon the position of the pull-pin.

The foregoing general and preferred attributes of the invention will become increasingly apparent and better understood following consideration of the ensuing specification and claims, taken in conjunction with the attached drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1

is a frontal perspective view of a preferred breakaway switch assembly embodiment in accordance with the invention;

FIG. 2

is an exploded perspective view of the embodiment shown in

FIG. 1

;

FIG. 3

is an exploded overhead plan view of the apparatus shown in

FIGS. 1 and 2

, showing the pull-pin in withdrawn position;

FIG. 4

is a bottom view of,the top closure member for the switch housing;

FIG. 5

is an overhead plan view similar to

FIG. 3

but showing the pin in fully engaged position;

FIG. 6

is an enlarged central sectional view of the structure shown in

FIG. 5

;

FIG. 7

is an enlarged side view of the pull-pin, showing a first side thereof;

FIG. 8

is an enlarged side view of the pull-pin rotated 90° from the position shown in

FIG. 7

;

FIG. 9

is an enlarged fragmentary perspective view showing a second embodiment of the pull-pin and switch unit, with the pin disposed in a first position;

FIG. 10

is a view like

FIG. 9

showing the same structure but with the pull-pin in a second position;

FIGS. 11

,

12

, and

13

are fragmentary cross-sectional views similar to

FIG. 6

but showing a third of the pull-pin in various positions of partial and full insertion; and

FIG. 14

is a perspective view of the pull-pin embodiment shown in

FIGS. 11-13

inclusive.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1

illustrates a breakaway switch assembly

10

in accordance with the invention, shown in fully assembled condition. Basically, switch assembly

10

comprises a partially enclosing main housing

12

and a top closure member

14

therefore, with which it forms a complete housing enclosure. Main housing

12

includes a rearwardly extending portion

16

which is preferably integral with the main housing and which preferably includes a mounting hole

18

by which the housing may be readily mounted to a trailer or the like by a bolt or the like, which if not fully tightened will provide a pivotal mounting for the switch assembly. In addition to the attachment extension

16

, a pair of electrical conductors

20

exit the housing enclosure

12

,

14

at its rearward extremity, and at the front a pull-pin actuator

22

is seen in fully engaged position. As illustrated, pull-pin

22

preferably includes an open-centered loop-like bail

24

by which it may be secured to a cord or chain, etc. attached to the towing vehicle.

FIG. 2

illustrates the housing top

14

lifted from the main housing

12

to reveal the interior of the latter, and also shows pull-pin

22

withdrawn from housing

12

. In addition,

FIG. 2

illustrates the preferred type of self-contained switch unit

26

, which is easily but securely mountable inside housing

12

by interfitting it between wall-like flanges

28

,

28

A, and

30

inside housing

12

, as further illustrated in FIG.

3

. It will be noted that switch unit

26

includes a pair of laterally extending flanges

26

a

,

26

b

at opposite sides. Flange

26

b

nests between housing flanges

28

and

28

a

, and flange

26

a

rests flush against housing flange or wall

30

. Switch

26

is a self-contained unit, preferably of a type commercially available on an economical basis, such as that sold by CW Industries of Southamton, Pa. and identified as part no. GRS-4011C-XXX (SP/ST, momentary/NC). Preferably, this switch unit includes an outer enclosure or body

32

which integrally forms the mounting flanges

26

a

,

26

b

. On opposite sides of switch body

32

, adjacent the mounting flanges

26

a

,

26

b

, a pair of resiliently deflectable or deformable spring arms

34

may be provided which help secure the switch

26

in a receiving opening, such as that provided between housing flanges

28

and

30

. As will be understood by those skilled in the art, switch units such as that just described, including the various physical attributes just noted, are well known in the art and readily available commercially. Of course, the selected switch must have adequate current-carrying capacity for the intended purpose, and where it must carry vehicle brake-actuating current that will likely be in the range of fifteen to thirty amps.

In the mounted position of switch unit

26

, shown in

FIGS. 3

,

5

, and

6

, the self-contained unit is securely held in the illustrated position by the various flange walls referred to above, which are disposed in mutual contact, with the spring arms

34

exerting at least light spring force against the end extremities of flanges

28

and

30

. Switch body

32

includes a rearwardly projecting shelf-like extremity

36

, and this rests upon an upwardly projecting flange wall

38

(

FIGS. 2 and 6

) that forms an integral part of the main housing

12

. The bottom of switch unit

26

(body

32

) rests upon the bottom inside surface of main housing

12

, and the housing top

14

preferably includes a downwardly projecting wall-like flange whose end extremity bears against the top of switch body

32

when housing top

14

is mounted in place upon the main housing

12

(FIG.

6

). Thus, switch unit

26

is securely and reliably captured in place inside the housing enclosure, and has no freedom of movement in any direction. As illustrated, switch unit

26

has a pair of rearwardly extending terminals located directly above the shelf-like projection

36

, which may in the form of spade terminals that slidably receive closely fitting C-shaped crimped-on conductor terminals

21

for easy attachment of the electrical conductors

20

to the switch unit. Conductors

20

are preferably separated along substantially their entire length inside housing

12

by an upright partition wall

13

, and the conductors exit housing

12

at the rear, over the top of the rearwardly extending portion

16

, in a manner described in more detail subsequently.

Preferably, the partition line between housing top

14

and main housing

12

in the area adjacent pull-pin

22

occurs at a point well above a cylindrically tubular receiver portion

38

, which is therefore entirely defined by, or part of, main housing

12

(FIG.

6

). Accordingly, receiver

38

is not subject to deformity or irregularity in shape due to manufacturing tolerances or manufacturing processes (e.g., molding), and is smoothly and regularly tubular inside. Therefore, pull-pin

22

slides smoothly and freely inside receiver

38

and maintains a generally uniform retention force therewithin caused by resilient deflection of a pair of spring arms

40

which preferably comprise an integral part of pull-pin

22

. Further, both the top

14

and main housing

12

define opposing walls

42

,

44

respectively which project toward one another when the top

14

is mounted in place upon the main housing

12

(FIG.

6

). Walls

42

and

44

preferably have centrally located semicircular reliefs or cutouts to provide a passage way for the end extremity of pull-pin

22

, but otherwise directly are in contact with one another on each side of pin

22

when top

14

is in place upon the main housing

12

. This helps rigidify the assembled housing structure and also provides an impediment to the passage of moisture or contaminants inside the housing enclosure through the tubular interior of receiver

38

.

The mutual alignment and initial securement of housing top

14

with respect to the main housing

12

is preferably accomplished by complementary and interengaging pins and recesses

12

a

,

12

b

, and

14

a

,

14

B which may be seen by reviewing

FIG. 2-6

inclusive. More particularly, upstanding tubular column

12

a

defines an internal recess that receives a downwardly-projecting pin

14

formed on top member

14

; similarly, main housing

12

has an upstanding post

12

b

that is receivable within a central recess defined by a downwardly projecting tubular column

14

b

comprising part of top

14

. Once so mounted in place, the top closure

14

and main housing

12

are preferably welded ultrasonically or otherwise joined permanently along their adjoining edges, which extend the entire periphery around the two such housing members except for a pair of very small openings at the rear through which the electrical conductors

20

exit the housing enclosure. These passageways are preferably made sufficiently small to closely accommodate (and preferably slightly pinch) conductors

20

, to thereby provide strain relief for them as well as reduce the likelihood of moisture migration into the interior of the housing enclosure, but they are also preferably sealed in a positive manner as well by injecting a sealant (e.g., silicone gel, etc.) into a tubular cavity

46

(see in particular

FIG. 6

) which surrounds a short length of the conductors

20

at the point where they exit the housing enclosure. Sealant cavity

46

is formed by correspondingly mating channel-shaped walls

46

a

,

46

b

formed on a the main housing

12

and top closure

14

, respectively, which come into mating registry with one another when top

14

is secured in place.

Pull-pin

22

is preferably an integral one-piece member made by injection molding or the like and formed of a non-conductive generally rigid polymer such as acetal polymer. As already indicated, pull-pin

22

includes an externally accessible bail

24

on one end, by which it may readily be secured (as by a lightweight rope, wire, cable, or other such tether) to the towing vehicle or other such device (referred to broadly as a joined member or component which is joined to another such member or component and whose relative motion is to be detected). In addition, pull-pin

22

preferably includes a circular collar

48

adjacent bail

24

which fits snuggly against the outer end surface of receiver

38

when the pull-pin is fully inserted into the receiver and, adjacent collar

48

, a pair of cylindrical sections

50

and

52

, the first of which fits snugly inside the end of receiver

38

and the second of which slides inside the latter with minimal clearance when the pull-pin is fully inserted therein (as shown in

FIG. 5

for example). Further, pull-pin

24

includes the previously mentioned spring arms

40

, which may be formed on opposite sides of the pin and extend part way along its length. Along the major portion of its length, this embodiment of pull-pin

22

has a generally X-shaped or cruciform cross section defined by a pair of mutually orthogonal elongated wall sections

22

a

,

22

b

(

FIGS. 2-8

inclusive), which may provide longitudinal guiding surfaces with respect to the tubular interior of receiver

38

and the circular central opening defined in housing walls

42

and

44

mentioned previously, through which pin

22

passes to access the self-contained switch unit

26

.

In the first embodiment of pull-pin

22

(illustrated and described in FIGS.

2

-

8

), this member has a somewhat conically tapered end extremity

54

which, in the fully inserted position of pin

22

, bears directly against and operatively moves an operating member

56

of switch unit

26

. In the illustrated embodiment, operating member

56

comprises a rocker member but it could in a broader sense be practically any analogous push-type component, all of which are collectively referred to herein as “a push button.” This movement of operating member

56

actuates switch

26

to its normal operating condition which prevails during times when there is no unexpected breakaway or relative motion between the joined components (e.g., towing and towed vehicles). That is, as will be understood, the switch unit

26

includes an internal switching mechanism, e.g., a pair of contacts or the like, which operate to complete or interrupt a path for current flow through the switch unit via conductors

20

. Upon relative movement of the joined components, however, pin

22

will be pulled longitudinally outwardly with respect to receiver

38

directly in accordance with the extent to which the joined components (e.g., towing and towed vehicles) have moved apart. If pull-pin

22

is so retracted, at least to the extent shown in

FIG. 6

(or further, even to the extent it is fully withdrawn from switch assembly

10

), the switch operating member (rocker, etc.

56

) immediately moves to its opposite position, in which it actuates the internal switch mechanism to an opposite condition of conductivity, i.e., to either complete or interrupt a circuit path through the switch unit. (As will be understood, switch unit

26

may of either a “normally closed” or “normally opened” circuit configuration, and the operating member

56

should be spring-biased so as to automatically return to its original position (i.e., as shown in

FIG. 3

) when pin

22

is so withdrawn.)

In this operation, it will be noted that the integral spring arms or fingers

40

of pull-pin

22

function to maintain a positive and predetermined retention force with respect to receiver

38

whereby inadvertent withdrawal of the pull-pin during operation is substantially precluded. No part of pull-pin

22

actually touches or operates the electrical switch contacts or any related electrical switch mechanism inside switch unit

26

, contrary to the conventional practice followed heretofore. Thus, switch unit

26

may be of a conventional nature which may be purchased economically in the market place and which has both well-established and consistent actuation characteristics and current-carrying capabilities, unlike the essentially custom-made, complicated spring-like internal contacts heretofore conventionally used in breakaway switches. In addition, switch unit

22

preferably has an enclosing body

32

which protects the internal contacts/switch mechanism of switch unit

26

from moisture or the like even if it does enter the adjacent area, unlikely as that may be due the closely interfitting character of the pull-pin

22

and receiver

38

, the adjoining internal housing walls

42

and

44

, and the housing flanges or walls

28

,

28

a

, and

30

which interfit closely with the extending flange portions

26

a

,

26

b

of switch unit

26

. In this regard, an O-ring (not shown in

FIGS. 1-8

) may be used on pin

22

at the point where it enters receiver

38

, to positively seal that area when the pin is in place. As already pointed out, there is little or no likelihood that moisture or other contamination will enter the housing past the electrical terminals

21

, since they are disposed within the sealed cavity formed by the closely interfitting housing and top walls

46

a

,

46

b

, as well as by the sealant injected into sealant cavity or pocket

46

.

FIGS. 9 and 10

illustrate a modified form or alternative embodiment of the pull-pin, designated by the numeral

122

, which may be used in a component configuration wherein switch unit

26

is positioned differently within housing

12

(by appropriately reconfigured internal walls, not specifically shown), such that the switch unit

34

is rotated essentially 90° from its position as shown in

FIGS. 3-6

inclusive, i.e., with the switch operating member (e.g. rocker

56

) disposed essentially parallel to the longitudinal axis of the pull-pin and receiver

38

. In this configuration, pin

122

slides across the switch operating member rather than meeting it directly at right angles. In this form, pull-pin

122

has the indicated conical sections

154

which enable it to approach rocker

56

in the manner shown in FIG.

9

and move across it to the position shown in

FIG. 10

, in which rocker

56

moves from one of its alternative positions to the other, and the opposite happens as pull-pin

122

is withdrawn.

FIG. 11-14

inclusive illustrate another modified form or alternative embodiment of the pull-pin, designated by the numeral

222

, which is shown in a configuration analogous to that depicted in

FIGS. 1-8

inclusive but also directly usable in the configuration of pull-pin

122

, referred to in the preceding paragraph, for use with switch units mounted in the alternative position discussed therein. In the form illustrated, pull-pin

222

comprises an elongated circularly cylindrical member having a rounded protruding forward end

62

for directly abutting contact with switch unit rocker (or push button)

56

in the same manner as pull-pin

22

, discussed in connection with

FIGS. 1-8

inclusive. Unlike pull-pin

22

, pull-pin

222

does not spring arms

40

or the like but instead incorporates a pair of resiliently flexible O-rings

66

and

72

which cooperate with the interior of a slightly different receiver

38

a

to hold the pull-pin in place therewithin.

That is, as seen in

FIGS. 11

,

12

, and

13

, receiver

38

a

includes an inwardly projecting annular wall portion

72

which is sized in relation to the outside diameter of pull-pin

222

and its forwardmost O-ring

64

such that O-ring

64

must be compressed (as shown in

FIG. 12

) in order to slide over the diametral constriction represented by annular flange

72

. Upon further insertion of pull-pin

222

, O-ring

64

clears the innermost edge of annular flange

72

(as shown in

FIG. 13

) and at this point its rounded forward end

62

depresses switch unit rocker

56

to cause switching operation of switch unit

26

. In this position, pull-pin

222

is resiliently but firmly locked in place in its switch-actuating position, and it will retain itself in this position until forcibly withdrawn from receiver

38

a

through resilient compression of O-ring

64

.

Preferably, pull-pin

22

also includes an outer O-ring

66

which seats in an annular groove formed in the larger cylindrical portion

52

of pull-pin

222

located adjacent its outer flange

48

. O-ring

66

compressively fits within a chamber

70

formed immediately inside the outer end extremity of receiver

38

a

, whose diameter is sized to require resilient compression of O-ring

66

in order to seat it in place therein. To facilitate this process, the entrance to recess

70

in the end of receiver

38

a

is preferably chamfered or angularly relieved, as indicated by numeral

68

. The resilient compression of O-ring

66

when seated within recess

70

also serves a retaining function for pull-pin

222

, but its principal purpose is to seal the interior of housing unit

12

,

14

from moisture and foreign elements which might otherwise move past the outside of the pull-pin in actual usage. As in the case of pull-pins

22

and

122

, pin

222

also preferably includes an outer bail designated

224

, by which the pull-pin may readily be connected to the towing vehicle for forced retraction from receiver

38

a

upon decoupling of the towed vehicle.

The above description is considered that of the preferred embodiments only. Modifications and variations of this and other such embodiments may well occur to those skilled in the art and to those who make or use the invention after learning of it through access to such preferred embodiments. Accordingly, it is to be understood that the embodiments shown in the drawings and described above are merely for illustrative purposes and should not be used to limit the scope of the invention, which is defined by the following claims as interpreted according to the principles of patent law, including the doctrine of equivalents.