The invention relates to an electrical switch in which a common contact body and a first selective contact body and a second selective contact body are provided in a housing. A movable contactor that can be moved outside of the housing against spring force produces the electrically conducting connection between the common contact body and either the first or the second selective contact body. A switch of this type is known for instance from DE 44 20 665 B4.
In this known switch, the contact surfaces of the first selective contact body and of the second selective contact body are set in a wall of the switch housing. The contactor is a sliding body that is provided with an actuating member that projects from the housing. Added to the sliding body is a contact plate that has a projecting contact finger. The contactor is pressed into its final position by a compression spring in the form of a helical spring. The helical spring produces the electrically conducting connection between the contact finger and the common contact body set in the housing. In the first final position, effected by the helical spring, the contact finger located on the contactor is positioned against the contact surface of the first selective contact body. When there is pressure on the actuating member, the contactor is displaced against the restoring force of the helical spring into its second final position in which the contact finger is positioned against the contact surface of the second selective contact body.
Switches of this type are embodied in the fields of miniaturization and subminiaturization and perform switching tasks in which a normally closed electrical contact is temporarily interrupted by the mechanical effect on the actuating member and the conducting connection is produced on a normally closed second contact.
Switches of this type are particularly suitable for position detection tasks in automatic production processes. However, typical areas of application can also be lock systems in vehicle bodies and interior areas of a motor vehicle as well as various position queries in household devices or other mechanisms.
Given that in the known switch in accordance with DE 44 20 665 B4 the contact finger of the contactor slidingly alternates from contacting the first contact surface to contacting the second contact surface, what is achieved is that the switching behavior can be intentionally influenced. The influencing variables are primarily the slide path of the contact finger, the size of the contact surfaces, and their distance from one another. These variables can be optimized with respect to one another. For instance, it is possible to maintain a strict separation between both switching positions, or to prevent an intermediate position in which both contact surfaces are in conducting contact with the contact finger. Furthermore, what a switch of this type achieves is that the switching process reliably occurs at a desired point in time regardless by whether the actuation from outside occurs rapidly or slowly.
In the known switch in accordance with DE 44 20 665 B4, it is disadvantageous that the current-conducting connection requires a plurality of components starting from the fixed common contact body via the helical spring and the contact plate up to the contact finger and in addition requires the sliding body of the contactor for holding or positioning these components. Moreover, a narrow side of the plate-like body of the contactor must be guided very precisely along the flat housing wall in which the contact surfaces of the first and second selective contact bodies are set. The contactor must not jam or become canted. This requires extremely precise manufacture of the individual parts and complex assembly if reliable functioning is to be assured over extended periods of time.
Known from EP 1 533 823 A1 is another switch in which a common contact body is selectively connected to a first or a second selective contact body using a contactor. In this case, the contactor is an elastically deformable leaf spring that receives from a tongue formed by it a pre-tension in the longitudinal direction and that is therefore urged to assume a curved shape. With the entire width of its free end the leaf-shaped contactor engages in the intermediate space of correspondingly formed areas of the selective contact body. The surfaces of these areas run parallel to the surface of the leaf-shaped contactor. The electrically conducting connection between the contactor and one of the two selective contact bodies can be produced using additional small contact bodies that are disposed at the free end of the leaf-shaped contactor and at the aforesaid areas of the first and second selective contact bodies. The surface of the leaf-shaped contactor and the surfaces of the aforesaid areas on the selective contactors run parallel to one another. The switching state is changed in that an actuating member acts on the opposing free end of the leaf-shaped contactor. The actuating member is acted upon by a compression spring, exerting a tensile force on the end of the leaf spring opposing the switching area. The leaf-shaped contactor obtains an extended shape from the tensile force. When the actuating member is depressed, the leaf-shaped contactor relaxes under the effect of its internal tension, transitions to its curved shape, and thus moves into the opposing switching position in which it is connected, electrically conducting, to the second selective contact body. The switch in accordance with EP 1 533 823 A1 is thus a so-called “sensitive switch” that has other switching properties than the earlier aforesaid switch in accordance with DE 44 20 665 B4. Above all it is not possible to precisely adjust the switching function with the switch in accordance with EP 1 533 823 A1 as it was described in the foregoing. In addition, the aforesaid special switching bodies must be placed on the switching free end of the elastically deformable contactor in accordance with EP 1 533 823 A1, likewise on the surfaces of the opposing areas of first and second selective contactor, which surfaces cooperate therewith; otherwise it is not possible to produce a reliable electrical contact.
The underlying object of the invention is therefore to create an electrical switch in which during a switching procedure the switching behavior can be precisely adjusted regardless of the type of operation and which also enables an intermediate position with contact to both selective contact bodies and which still enables reliable operation over extended periods of time with a simple structure, simple production, and simple assembly.
In the inventive electrical switch, an elastically deformable contactor is provided in the basic form of a leaf spring. The deformation state of this contactor is altered by the effect of an actuating member. The contactor is provided with contact fingers that project from the plane of the leaf spring and that can slidingly cover contact surfaces that are embodied on the first and second selective contact bodies. The sliding covering of the contact surfaces by the contact fingers like a type of sliding contact effects self-cleaning of the contact surfaces. This is important if the switch must be operated under unfavorable environmental conditions and for instance oxide layers, silicate layers, or other undesired deposits can occur on the contact surfaces. Foreign layers that disturb functionality can frequently be removed mechanically. Sliding contacts can remove even foreign particles or wear particles from plastic parts from the common surface for contact fingers and contact surfaces. In principle no discrete restoring spring is required for the actuating member.
The elastically deformable contactor formed from the basic form of a leaf spring can be produced economically as a simple punch part with bent elements and is nevertheless a multifunction part that combines the function of a movable switching part, an electrically conducting contact, and a restoring spring.
A second aspect of the invention relates to the functional division of the contactor, on which is provided one after the other a fastening area, a central deformation area, and an adjacent stiffened actuating area from which the contact fingers originate. The contactor can have a step-like shape, a U-shape, or an angular shape. What is intended with a step-like shape is that the fastening area and the actuating area are in two different planes—similar to a Z shape—and are joined to one another by the deformation area that is disposed therebetween and that extends approximately perpendicular thereto. In a contactor that has a U-shape, the fastening area and actuating area are likewise in different planes; however they face one another, whereby the leg of the U forms the deformation area. For the angular shape, the apex area of the angle replaces the leg in the U-shape. The configuration thus described requires the contactor to be a multifunctional part.
The embodiment in accordance with the second aspect of the invention is associated with the additional advantage that the extension of the fastening area, deformation area, and actuating area can be distributed differently over the length of the contactor. In the design of the switch, a different translation ratio can be selected and set between the movement of the actuating member and the switching paths of the contact fingers. This means another variation option for the switching behavior. In contrast, in the aforesaid switch in accordance with DE 44 20 665 B4, the actuating member and the contactor are joined to the contact plate in an unchangeable common linear movement. The movement of the actuating member and the contact finger is thus rigidly established at a ratio of 1 to 1.
For the great majority of tasks, the internal tension or pre-tension of the contactor is adequate to effect the required return into the preferred switching position. When necessary, however, in accordance with a third aspect of the invention a reinforcing compression spring can also be added.
A fourth aspect of the invention provides options for stiffening the actuating area, while a fifth aspect of the invention is a particularly advantageous option for placing the contact fingers against the actuating area.
Sixth and seventh aspects of the invention include an advantageous embodiment of the contactor and the selective contact bodies as they are used in particular in a contactor having a step-shape.
Eighth and ninth aspects of the invention provide advantageous configuration options that are based on the embodiment of the contactor in a U-shape.
Tenth and eleventh aspects of the invention are modified embodiments based on the design of the contactor in an angular shape.
In specific configurations of contactors according to the invention, a pivoting movement for the actuating member generally occurs because the deformation area of the leaf spring is relatively precisely localized.
It should furthermore be stressed that in all of the embodiment types the contact fingers bent out from the contactor move with their wide side onto the contact surfaces of the two selective contact bodies. Even if the ends of the contact fingers that act as sliding contacts are embodied angled or curved in the conventional manner, there is a narrow contact surface, the wide side of which moves over the contact surfaces of the selective contact bodies. This is a clear difference from the prior art in accordance with DE 44 20 665 B4 and supports assured switching behavior as well as self-cleaning of the switch. Likewise, in contrast to the prior art, the arrangement of the contact fingers in pairs substantially strengthens switch reliability due to their redundancy.
The invention shall now be explained in greater detail using exemplary embodiments that are illustrated in the figures. The figures depict the following:
A connector contact 4a is embodied at the bottom of the common contact body 4, likewise a connector contact 5a is embodied at the bottom of the first selective contact body 5 and a connector contact 6a is embodied at the bottom of the second selective contact body 6. The function of the switch is to connect in an electrically conducting manner either to the connector contact 5a or to the connector contact 6a depending on the switching position of the connector contact 4a.
A contactor 9 made of an electrically conducting, elastically deformable material is used for this. The basic form of the contactor 9 is that of a leaf spring that is bent into somewhat of a Z-shape (see
A first pair of contact fingers 13 and a second pair of contact fingers 14 are formed on the edge strips 12 of the contactor 9. The contact fingers 13 of the first pair oppose one another, as do the contact fingers 14 of the second pair. The contact fingers 13 and 14 are bent inward from the plane of the edge strips 12 and have an offset shape so that they can bend outward resiliently.
The distance between the contact fingers 13 and 14 that are arranged in pairs is dimensioned such that they can wrap around the flat, plate-like first and second selective contact bodies 5 and 6 and surround them from both sides. With the apex areas of their offset sections, the contact fingers 13 and 14 are resiliently positioned against contact surfaces 5b and 6b of the selective contact bodies 5 and 6.
The precise allocation of the contact fingers 13 and 14 to the contact surfaces 5b and 6b in accordance with the construction of the switch can be seen in
In the depiction in
Thus in the first switching position (
The actuating member 18 is used to transition the contactor 9 from its first switching position to its second switching position. Its control head 18a projects outward through the cover 3 of the switch, whereby the through-opening located in the cover 3 is sealed by a sealing collar 19. The actuating member 18 terminates fork-like in two arms 18b that form a pressure surface 18c and that wrap around the slide-and-grab latch 15 of the contactor 9 (see
Downward pressure on the actuating member 18 overcomes the internal tension or pre-tension of the contactor 9. The latter is elastically deformed and its actuating area 9c transitions downward into the second switching position in accordance with
The contactor 9 comprising an elastic and electrically conducting material is a multifunction part that can both provide the contact via the contact fingers 13, 14 and also return the actuating member 18 to the first switching position. In practice, the switch is used in the field of sub-miniaturization; the control head 18a of its actuating member 18 is for instance actuated by a moving cam in a mechanical or hydraulic control device.
The subject of
Otherwise, the configuration in accordance with the first embodiment is retained for the most part. Like the first selective contact body 22 and the second selective contact body 23, the common contact body 21 has a flat, plate-like configuration along with connector contacts 21a, 22a, and 23a. The contact areas 26a of the contact fingers 26 are drawn in offset inwardly to the width of the two selective contact bodies 22, 23 and are bent cross-sectionally in a V-shape, whereby the interior apex lines 26b of the V-shape form sliding contacts that resiliently cover the contact surfaces 22b, 23b of the first and second selective contact bodies 22, 23 (
For cooperating with the actuating member 18, at its end opposing the contact fingers 26 the contactor 26 has a sliding curvature 27 that forms the end of the actuating area 25c. The common contact body 21 terminates at the top in a rivet-like fastening head 24 that passes through an opening in the fastening area 25a of the contactor 25 and thereby fastens the latter mechanically and in an electrically conducting manner.
The latter again has the basic or initial shape of a flat leaf spring that extends in its longitudinal direction across all three contact bodies 31, 32, and 33. The fastening area 35a of the contactor 35 is curved downward and back out of the starting plane until it runs at an acute angle to the rest of the contactor 35 (
The remaining area of the leaf spring forming the contactor 35 is divided by two longitudinal recesses 39 that run in its longitudinal direction and that project into the center area of the contactor 35 starting from the free end of the contactor 35 that opposes the fastening area 35a. The longitudinal recesses 39 separate a center bar from two contact fingers 40 that are bent at an angle out of the plane of the leaf spring in the same manner as a fastening area 35a and that form sliding contacts with their resilient ends. In contrast, the center bar is stiffened with a reinforcing bead or rib 38 and remains largely in the original plane of the leaf spring. It thus forms the actuating area 35c of the contactor. If the additional compression spring 17, cited in the foregoing, is to be used, the free end of the actuating area 35c is provided with an engaging end 41 that engages in the compression spring 17 (
In those cases in which the holding and restoring force of the contactor 35 is adequate for proper switch functioning, it is preferred that the free end of the actuating area of 35c is designed with a slight curvature.
When assembled, the contactor 35 receives a longitudinal tension because with its fastening end 35a on its one side and with the resilient contact fingers 40 on its other side it wraps around a center area of the base 1. This results in adequate pressure for the resilient ends of the contact fingers 40 acting as sliding contacts. In the embodiment in accordance with
Number | Date | Country | Kind |
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05020267 | Sep 2005 | EP | regional |
Number | Name | Date | Kind |
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3786209 | Bury | Jan 1974 | A |
5075516 | Brouillette | Dec 1991 | A |
5369238 | Hirata | Nov 1994 | A |
5463198 | Shimaoka | Oct 1995 | A |
5568860 | Stringwell et al. | Oct 1996 | A |
6791038 | Lai | Sep 2004 | B1 |
Number | Date | Country |
---|---|---|
4420665 | Dec 1994 | DE |
1088616 | Oct 1967 | EP |
1288985 | Mar 2003 | EP |
1533823 | May 2005 | EP |
Number | Date | Country | |
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20070062796 A1 | Mar 2007 | US |