Abstract:
A sealed proximity switch assembly comprising a housing of non-magnetic material, contacts mounted in the housing, a movable contact member of electrically conductive material mounted within the housing for movement toward and away from engagement with the contacts, a spring yieldingly urging the contact member into engagement with the contacts, and a magnet within the housing and connected to the contact member such that when a portion of a movable member is in proximity with the housing, the magnet is attracted toward the portion moving the contact member out of engagement with the contacts.

Description:
This invention relates to proximity assemblies. 
     BACKGROUND AND SUMMARY OF THE INVENTION 
     Proximity switches which are actuated by relative movement between members are well known in the art. For example, in automobiles and the like, it is common to provide a proximity switch in the form of a door jamb switch on the body of an automotive vehicle which is actuated when the door is closed to electrically disconnect one or more lights within the vehicle and is deactivated when the door is open to make a connection illuminating the lights within the vehicle. 
     One of the problems in connection with such proximity switch assemblies is that the electrical connections must be insulated from moisture and the like. This necessitates the use of elastic boots. 
     Among the objectives of the present invention are to provide a sealed proximity switch assembly which obviates the need for special protection or isolation against moisture; which utilizes a sealed housing; which incorporates a minimum number of parts and therefore is simpler to manufacture and is less likely to malfunction; and which is automatically adjustable for tolerances. 
     In accordance with the invention, the sealed proximity switch assembly comprises a housing of non-magnetic material contacts mounted in said housing, a movable member of electrically conductive material mounted within said housing for movement toward and away from engagement with said contacts, a spring yieldingly urging the contact member into engagement, with the contacts, a magnet within said housing and connected to the contact member such that when a portion of a movable member is in proximity with said housing, the magnet is attracted toward the portion moving the contact member out of engagement with the contacts. Means are provided for automatic adjustment when the switch assembly is first positioned in the vehicle. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of a sealed door jamb switch assembly embodying the invention. 
     FIG. 2 is a longitudinal sectional view of the switch assembly on an enlarged scale showing the switch assembly when it is first assembled on a vehicle. 
     FIG. 3 is an end view taken from the left as viewed in FIG. 2. 
     FIG. 4 is an end view taken from the right as viewed in FIG. 2. 
     FIG. 5 is a view similar to FIG. 2 showing the switch assembly after it has been mounted on a vehicle and the door is closed. 
     FIG. 6 is a view similar to FIG. 5 with the door open. 
     FIG. 7 is a longitudinal sectional view similar to FIG. 3 of a modified sealed door jamb switch. 
     FIG. 8 is a longitudinal sectional view similar to FIG. 5 showing a further modified sealed door jamb switch. 
    
    
     DESCRIPTION 
     Referring to FIGS. 1-6, the sealed proximity switch is shown as used in a door jamb switch assembly for an automotive vehicle. The sealed door jamb switch assembly 10 embodying the invention comprises a sealed housing 11 that supports at one end spaced contact members 12, 13, 14 which are embedded in an end member 15 that closes and seals the housing 11. The contacts 12, 13, 14 extend axially inwardly into the sealed portion 16 of the housing. A contact member 17 having a conical end terminating in a convex top is yieldingly urged toward the contacts by a compression spring 18. A permanent magnet 19 is fixed to the contact member 17 so that the magnet member 19 and contact member 17 are movable together. The other end of the housing 11 is closed by an integral wall 20. Spring 18 comprises a helical spring surrounding magnet 19 and interposed between wall 20 and the contact member 17. 
     A mounting cover 21 that is tubular and extends over the periphery of the end of the housing 11 and includes a flange 22 for engaging a panel or other portion of a door jamb of a automotive vehicle. Circumferentially spaced flat spring members 23 are mounted on the exterior of the housing 11 and snap behind a flange 24 that defines the opening into which the switch assembly 10 is inserted. 
     In order to accommodate for tolerances in vehicle manufacture, provision is made for automatic adjustment of the switch assembly which includes radially inwardly extending and radially movable symmetrical serrations or teeth 25 on the tubular portion of the cover 21 and a plurality of complementary longitudinally spaced serrated teeth 26 on the housing 11. 
     The housing 11 and cover 22 are made of non-magnetic material, preferably plastic such as acetal resin. 
     When the switch is first mounted in a vehicle, automatic adjustment occurs when the door D is closed and engages the housing 11 causing the housing 11 to move axially inwardly to the position shown. During this movement, there is a ratcheting action between serrations 25 and teeth 26 as may be required to accommodate tolerances, as shown in FIG. 5. At the same time, the magnet 19 is attracted by its magnetic field toward the ferromagnetic portion of the door D. As the magnet is moved to the left relative to housing 11, it carries the associated contact member 17 to the left thereby interrupting the circuit with the contact members 12, 13, 14. Thereafter, when the door opens the housing 11 and cover 21 remain in the adjusted position as shown in FIG. 6. 
     When the door of the vehicle is opened, the magnet attraction to the ferromagnetic portion of the door D and the magnetic field of the magnet are broken so that the spring 18 moves the magnet and associated contact member to the right as viewed in FIG. 6 making contact as required. 
     The modified form of the switch 10a shown in FIG. 7 is similar to the first form except that contact 17a is hollow thereby reducing the weight of the contact 17a. Contact 17a includes a cylindrical portion 17b into which the cylindrical magnet 19a extends and an integral shoulder 17c against which the magnet 19a abuts. Contact 17a further includes an integral frustoconical portion 17d and an end portion 17e. This form of switch has the advantage of utilizing a cylindrical magnet 19a that does not require special shaping to receive the contact 17a, as contrasted to the form of jamb switch shown in FIGS. 1-6. 
     As in the previous forms of the invention, the switch 10a includes a sealed portion 16a of housing 11a, and contact members 13a, 14a as well as a spaced contact member (not shown) which are adapted to engage the frustoconical portion 17d of contact 17a. The switch 10a also includes a housing, a mounting cover 21a and flange 22a as well as serrations or teeth 25a, 26a, flat springs 23a. 
     The modified form of switch 10b shown in FIG. 8 differs primarily in that it utilizes a different configuration of contact 17f and contact members 13b and 14b. A similar third contact member (not shown) is provided in circumferentially spaced relation to contact members 13b, 14b. Contact 17f includes a cylindrical portion 30 into which the cylindrical magnet 19b extends and abuts against a transverse annular portion 31. The contact 17f includes a further cylindrical portion 32 that extends axially and is adapted to be engaged by the ends of the contact members 13b and 14b as well as the third contact member (not shown). In the door closed position, the contact members 13b, 14b rest upon a cylindrical insulator ring 33, as shown in FIG. 8, which is supported by a further tubular portion of smaller diameter on the end of the contact 17f. Insulator ring 33 is made of plastic insulating material which is arc resistant. As in the previous forms of the invention, the switch 10b includes flat spring members 23b, a housing 20b, mounting cover 21b, and an integral wall 22b. 
     Prior to the first door closure, the housing 11 extends beyond the panel or other portion of a door jamb, as in the previous forms of switch. When the door is first closed, spring 18b is compressed and the housing 11 is forced axially inwardly and retained in the adjusted position by engagement of the teeth 25b, 26b. In this position, the magnet 19b is drawn against the door panel. When the door is open, the magnet 19b is no longer attracted to the door panel and spring 18b drives the contact 17f so that the contact members engage the cylindrical portion 32 completing a circuit to energize one or more lights. At the same time, a second spring 36 interposed between the housing 11b and cover 21b moves the housing 11b outwardly a short distance to assure that the door will make intimate contact with the housing upon the next closing of the door. 
     In this form, the flexing of the contact members 13b and 14b against the insulator bar 33 and contact portion 32 provides the same force on each so that there is strong contact pressure. The magnet, on the other hand, need only be strong enough to overcome the axial frictional component of force and therefore can be made as small as possible. 
     Although the proximity switch embodying the invention has been described as having utility in connection with a door jamb switch assembly, it can be used wherever a proximity switch is required between members that are moved relative to one another. 
     It can thus be seen that there has been provided a sealed proximity switch assembly which obviates the need for special protection or isolation against moisture; which utilizes a sealed housing; which incorporates a minimum number of parts and therefore is simpler to manufacture and is less likely to malfunction; and which is automatically adjustable for tolerances.