GB2131615A - Electrical switch for actuation by motor vehicle doors - Google Patents

Abstract

A switch comprises a housing 1 which contains a plunger 2 capable of being thrust axially inwards against a spring 3. The plunger 2 has, fixed to it, a terminal tang 7 with shoulders extending radially out beyond the diameter of the plunger 2. The switch is closed when the shoulders make conductive contact with the bottom 4 of the housing 1. The housing 1 itself is made of an electrically non-conductive synthetic resin, but a conductor 8b is provided for carrying the current, made of a corrosion-resistant material such as brass, copper or the like. The conductor 8b extends, on the outer surface of the switch housing 1, all the way from a screw-hole (10, fig 1) for taking an attachment screw which secures the switch to the frame of the vehicle, to a contacting point where the metal terminal tang 7 makes contact with the housing bottom 4, when the switch is closed. The plunger 2 may be sealed against the inner wall 11 of the housing 1 by an internal low-friction sealing ring or sealing disc 12. The seal can, for example, be injection-moulded integrally with the plunger 2. When the plunger 2 is actuated, the sealing ring or disc 12 slides along over the inner surface 11 of the switch housing 1. The sealing ring 12 can very well take the form of a leaf seal, preferably with two sealing lips (12a, 12b, fig 3a) extending radially outwards from the plunger 2. <IMAGE>

Description

SPECIFICATION Car door switch The invention relates to an electrical contact switch ofthe general kind described in the preamble of Claim 1, intended particularly for actuation by the doors of motorvehicles.

Switches of this kind are used for providing interior illumination when the door of the vehicle is opened, and for otherdoor-actuated switching functions.

Usually at least two ofthe doors are equipped with switches, sometimes four or even five. Consequently very low cost in manufacture is important, and this has sometimes resulted in poor product quality.

Good quality is essential because these switches must continue operating reliably although subjected to prolonged exposureto adverse weather. They must therefore resist corrosion.

In nearly all conventional door-switches the electric circuit is closed,when the doorofthe vehicle is opened, in that the switch housing is itself made of steel and is earthed to the doorframe by an attachment screw. When the door is opened this closes a switching contact, allowing currentto pass over the consumer (the electric lamp), overthe steel switch housing and over the attachment screw to the frame ofthevehicle, which acts asthe earth. The switching contact acts as the electric terminal ofthe switch. The path for the current therefore runs over the steel switch housing.In some cases at least one extra stamped conductor is provided for carrying the electric current from the switching contact to the earthed attachment screw, but this has proved an inconvenient arrangement in high-outputfinalvehicle assembly operations.

The intention in the present invention isto provide a door-switch of the general kind described in the preamble of Claim 1, but simpler in construction and less costly to manufacture than the conventional switches. Furthermore, the new switch shou Id be simple to install, not requiring extra connection parts of seals. And it must have better corrosion resistance than the conventional switches.

The problem is solved, according to the invention, as described in the characterising portion of Claim 1.

Further advantageous versions are described in Claims 2 to 10.

The invention starts out from the idea of replacing the conventional steel switch housing, which involves steel to steel contacting, by a housing made of a synthetic resin and arranged sothatitcan be mounted, well sealed against moisture, directly on the doorframeofthevehiclewithoutrequiring any extra parts, and providing a corrnsion-resistant electric conductorforconveying currentfrom the contacting location ofthe electrical terminal ofthe switch to the attachment location where the switch is attached to the frame of the car.

Consequently, in the switch of the present invention, current is conveyed by a conductor in the form of a stamped part, or a thin wire, or a printed-on conductor, made of a corrosion-resistant material such as brass, copper orthe like and fixed to the outer surface ofthe switch housing.

Particularly good results are obtained by extending the conductor, which is fixed to the outer surface ofthe housing, all the wayfromthe screw-hole provided in the housing to takethe attachment screw, to the opening in the bottom ofthe housing where the plungerpenetratesthroughthehousing bottom.The plunger can verywell be sealed against the inner wall ofthe housing with the help of an internal sealing ring or sealing dise of the kind described in one ofthe Claims 4to 7. This kind of internal seal can, if desired, be used in other door-switches ofthis general kind.

Further details and advantages ofthe switch orthe invention can be derived from the following description of the examples represented diagramatically in the drawing, in which: Figure lisa perspective view of the switch as seen fromthe back.

Figure2 is a backview as seen in the direction ofthe arrow II of Figure 1.

Figure 3 is a side-view ofthe switch, partly sectioned in the plan Ill-Ill of Figure 2.

Figure 3a is a side-view of a different version of the plunger.

Figure 4 is a top-view sectioned in the plane IV-IV of Figure 3.

Figure 5corresponds to Figure 3, but shows a different version ofthe switch.

Figure 6co rresponds to Figure 1, but shows a still further version ofthe switch.

Figure 7corresponds to Figure 3, but relates to the version of Figure 6.

Figures is a top-view ofthis version, sectioned in the plan VIII-VIII of Figure 7.

Figure 9 shows a modified sealing discforthe switch shown in Figure 6.

The switch ofthe invention comprises a housing 1 containing a plunger 2 capable of being pushed axially inwards, in breaking electrical contact, against the influence of a helical compression spring 3. When the plunger 2 is pushed inwards, in breaking electric contact, its inner end-portion 6 penetrates inwards through an inner opening 5 of the housing bottom 4.

Fixed to the inner end-portion 6 there projects still further inwards a metal electric contacting terminal tang 7 with lateral shoulders. When the plunger 2 is in its retracted position, as shown in Figures 1,3,4 and 5, the lateral shoulders of the tang 7 make electric contactwith an earthing conductor8, closing the electric circuit between the consumer (not shown) and earth.

The switch housing 1 is made of an electrically nonconductive synthetic resin. The earthing conductor 8, on the other hand, is made of a corrosionresistant metal, such as brass, copper or the like, and is arranged on the housing 1 in such a way that when the switch has been mounted on the vehicle with the help of an attachment screw, the screw provides good electric conductance between the earthing conductor 8 and the frame ofthe vehicle. When the switch is in its closed position (the plunger retracted) the terminal tang 7 is therefore reliably earthed. For mounting the switch on the frame ofthe vehicle the housing 1 has a flat-surfaced mounting plate9with a hole 10 to take the attachment screw.

In regard to the earthing conductor 8, this can take the form of a brass stamping 8a, for example, a wire 8b or a printed conductor 8c applied to the outer surface ofthe synthetic resin house 1. The earthing conductor 8 surroundsthe screw-hole 10 and, at its other end, surroundsthe inner opening 5 where the plunger end-portion 6 penetrates through the bottom 4 of the housing 1. When the switch has been mounted on the vehicle the conductor 8 therefore provides reliable earthing conductance, through the attachment screw; betweenthetang7(whentheswitch isclosed) and the frame of the vehicle.

To prevent invasion of condensed moisture orthe like into the interior of the switch, the plunger 2 is equipped with a sliding seal, as shown at 12 in Figure 3, which slides along in close contactwith the cylindrical innerwall 11 ofthe housing 1.

Forthis purpose, there can be mounted over the plunger 2, for example a sealing disc 12 made of a low friction sealing material.

Preferably, the sealing ring or sealing disc 12 is moulded integral with the plunger 2. Furthermore, as shown in Figure 3A, the seal can be constructed as a multiple leaf-seal comprising at least two lip-seals 12a, 12b extending radially and parallel to each other from the plunger shaft 2a. Easy sliding of the lip-seals 1 2a, 1 2b over the cylindrical inner surface 11 ofthe housing 1 can be assisted by lightly greasing or oiling the seals. Residual oil retained between the lip-seals 12a, 12bformsathinfilm of oil which helps to prevent moisture from reaching the interior of the switch.

Alternatively, oradditionally, the outer opening 13 ofthe housing (Figure 5) can, if desired, be sealed by an external lip-seal 14through whose middle opening the plunger 2 slidesfreely back and forth. When the plunger 2 is in its retracted position (Figure 5) the internal sealing disc 12 rests resiliently in contact with the external lip-seal 14.

The use of an internal seal arranged in this wayand which can, for example, be an O-ring seal, in conjunction with a switch housing made of a synthetic resin, whoseflat-surfaced flange 9 rests in close contact with theframe of the vehicle, makes it possible to prevent invasion of water, condensed moisture or the like, not only into the interior of the switch itself but also into the interior ofthe doorframe of the vehicle.

The seal can easily be mounted on the plunger, for example between the plunger head and the compression spring, at very little cost, making it unnecessary to use comparatively costly external seals, while providing a better sealing effect.

In Figures 6to 9, which show a variant of the invention, corresponding parts have been given the same reference numbers as in Figures 1 to 5. But in thisvarianttheconductor8is partly housed in recesses 15,16,17 between the screw-hole 10 and the contact surface for the terminal tang 7. And the switch housing 1 has a sealing ring 18, or a sealing disc 19, housed in a recess 20 ofthe housing plate 9 so as to make a good seal between the switch housing 1 and the frame ofthevehicle.

Claims (1)

1. An electrical contact switch, particularly for the doors of motorvehicles, with a housing containing a plunger capable of being thrust inward axially against the influence of a spring, the inner end-portion of the plunger penetrating inwards through an inner open- ing in the bottom ofthe housing and having,fixed to it, a contacting metal terminal tang which has shoulders extending laterally out beyond the radius ofthe plunger, the metal tang making electric contact, when the switch is closed, with the bottom ofthe housing, characterised in thatthe switch housing (1 ) is made of an electrically non-conducting synthetic resin and has an electric conductor (8) made of a corrosion resistant material such as brass, copper orthe like, the conductor (8) extending, on the switch housing (1), all thewayfrom a screw-hole (10),fortaking an attachment screw, to the location where the terminal tang (7) makes contact with the bottom (4) ofthe housing (1).

2. A switch as claimed in Claim 1, with at leastone screw-hole in the switch housing, characterised in that the housing has a stamped conductor (8a), a wire (8b) or a printed conductor (8c) attached to it externally, the conductor (8a, 8b, 8c) surrounding the screw-hole (10) and also surrounding the inner opening (5) in the housing bottom (4) through which penetrates the plunger (2,6).

3. Aswitch as claimed in Claims 1 or2,characte- rised in that a seal is interposed between the plunger (2) and the inner wall (11) ofthe housing (1).

4. Aswitch, particularly as claimed in Claim 1, characterised in that an internal sealing ring or disc (12) made of a low-friction material is mounted on the plunger (2) to slide along the surface ofthe innerwall (11) ofthe housing (1) when the plunger (2) is actuated.

5. A switch accordingto Claim 4, characterised in thatthesealing ring (12) is injection-moulded integral ly onto the plunger shaft (2a).

6. Aswitch as claimed in Claims4or5,characte- rised in thatthe sealing ring (12)isa leaf seal with at leastonesealinglip(12a,12b)extending radially outwards from the plunger shaft (2a).

7. Aswitch as claimed in Claim 6, characterised in that the leaf sea I com prises at leasttwo sealing lips (12a, 12b) arranged parallel to each other

8. Aswitch as claimed in one ofthe Claims4to 7, characterised in that at the front opening (13) ofthe housing the plunger(2) is surrounded by an annular lip seal (14).

9. A switch as claimed in one or more of the Claims 1 to 8, characterised in that between the screw-hole (10) and the contact location forthe terminal tang (7), the conductor (8) is partly housed in recesses (15,16, 17) in the switch housing (1).

10. A switch as claimed in one or more ofthe Claims 1 to 9, characterised inthattheswitch housing has a sealing ring (18) or sealing disc (19)forforming a seal between the housing (1) and the frame ofthe vehicle.

11. A switch, particularly for motor vehicle doors substantially as hereinbefore described with refer ence to any one or more ofthe accompanying drawings.

Superseded claims-1 Neworamended claims:-

1. An electrical contact switch, particularlyforthe doors of motorvehicles,with a housing containing a plunger capable of being thrust inward axially against the influence of a spring, the inner end-portion ofthe plunger penetrating inwards through an inneropen- ing in the bottom of the housing and having, fixed to it, a contacting metal terminal tang which has shoulders extending laterally out beyond the radius of the plunger, the metal tang making electric contact, when the switch is closed, with the bottom of the housing, the switch housings made of an electrically nonconducting synthetic resin and has an electric conductor made of a corrosion resistant material such as brass, copper or like,the conductor extending, on the switch housing, all the way from a screw-hole (10), fortaking an attachment screw, to the location where the terminal tang makes contact with the bottom ofthe housing characterised in that a seal is interposed between the plunger (2) and the innerwall (11) of the housing (1).