Electricity: circuit makers and breakers – Solid contact – Push button operated
Reexamination Certificate
2000-05-11
2001-07-03
Friedhofer, Michael (Department: 2832)
Electricity: circuit makers and breakers
Solid contact
Push button operated
C200S296000
Reexamination Certificate
active
06255612
ABSTRACT:
BACKGROUND OF THE INVENTION
Conventional control panels having control elements, for example having pushbutton switches or display elements in house doorbells, transport means, elevators, etc., envisage that one or more control elements are fastened to a front panel or introduced into said panel and the latter in turn can be fastened in the desired place. In the installation of such control panels, the control elements are fastened to the front panel in a first step, which can be effected, for example, by means of a screw nut which is screwed onto a thread provided on the control element. The front panel as a whole is then fastened. However, such a procedure does of course require that the front panel be prefabricated as a separate workpiece. The installation, too, can be inconvenient and tedious depending on the cabling of the control elements and depending on accessibility of the control panel. Moreover, the front panel must be detached as a whole if a control element is faulty.
It would therefore be desirable to be able to fasten a control element directly to an already installed front panel. Such a front panel then need not be a separate, prefabricated workpiece. It would also be entirely possible for the casing provided with suitable openings, the housing or the like of the article on which the control panel is to be mounted also to serve directly as the front panel. In this way, high costs both for the production of the control panel and for its installation would of course be saved. A known means for permitting the fastening of a control element to a front panel installed in a fixed position consists in providing the front panel with additional holes into which, for example, plastics arms provided with a sawtooth profile and mounted on the control element can be introduced, which arms then fix the control element to the front panel. An other solution is disclosed in the two U.S. Pat. Nos. 4,070,559 and 4,016,359. These two publications each disclose a control element which can be formed, for example, as a switch or lever or as an electrical insulator and can be fastened to a front panel with a circular opening. In these known cases, the control element has a housing with a cylindrical section and an annular groove running all round the cylindrical section. The cylindrical section is dimensioned so that it fits virtually without play into the circular opening. These known control elements furthermore each have an annular spiral spring which fits into the annular groove and serves for fastening the control element without additional fastening means, i.e. in the manner of a snap fastener, to the front panel. On insertion of the control element into said front panel, the spiral spring is pressed into the annular groove. It relaxes again in the inserted state and then rests against the inside of the front panel, with the result that the control element is fixed in the opening.
This known method of fastening has the disadvantage that the cylindrical section has to be dimensioned so exactly that it can be inserted into the opening of the front panel so that it fits tightly, i.e. without play, and that the control element is relatively expensive because the spiral spring has to be specially made for this purpose.
SUMMARY OF THE INVENTION
It is the object of the present invention to provide a control element which does not have the disadvantages of the known control elements, can be fastened in a simple manner to a front panel and furthermore is economical to produce. This object is achieved by a control element having at least one circular opening with diameter d
0
and a thickness T constant in the vicinity of this opening. The control element has a housing which has a front, a back and an essentially cylindrical section located in between and having a diameter d
T
, wherein
d
T
is slightly less than d
0
,
the housing has, at the front, a collar projecting laterally beyond and radially away from the cylindrical section and having a support surface making an angle of 90° with the cylinder surface and intended for supporting the front panel,
the cylindrical section has at least one groove running all around in a plane perpendicular to the cylinder axis and having a width d measured at its broadest point,
for the distance a from the middle of a groove to the support surface, measured parallel to the cylinder axis, t−b/2 <a<t+b/2,
a ring which comprises an elastically deformable material and whose external diameter is greater than d
0
is present in the groove, and
the ring is dimensioned and arranged in such a way that, in the state when inserted in the front panel, the control element is fixed in the opening by virtue of the ring being pressed against the lateral surface of the groove by the lower edge of the opening.
The present invention has substantial advantages compared with the prior art. Thus, it has the advantage that the housing of the control element can be produced in a very simple and economical manner. For example, if it is metallic, it can be produced by turning in a single operation. The installation of a control panel provided with control elements according to the invention is also very simple, and the control elements need only be provided with the necessary electrical connections and then inserted by pressing into the opening provided for them. For example, the installation in poorly accessible places is thus simplified and also permitted or simplified especially when the back of the control panel is not accessible or scarcely accessible. However, because of the control element according to the invention, the front panel in particular need not be a separately produced adapter. It can readily be formed by the casing, the housing or the like of the article on which the control panel is to be mounted. Thus, depending on circumstances, the production of a control panel provided with control elements according to the invention can simply consist in drilling at least one circular opening of a standard size in a casing formed, for example, by a metal sheet and then fastening the control element by manipulation. Compared with the customary prior art, this procedure does of course constitute a substantial simplification and is thus associated with considerable cost savings.
REFERENCES:
patent: 4016359 (1977-04-01), Gamble
patent: 4035597 (1977-07-01), Josemans
patent: 4070559 (1978-01-01), Piber
patent: 4156804 (1979-05-01), Piber
patent: 4306123 (1981-12-01), Taylor
patent: 4354074 (1982-10-01), Aurand et al.
patent: 5201408 (1993-04-01), Torma et al.
patent: 5541377 (1996-07-01), Stuhlmacher
patent: 33 13 145 A1 (1984-10-01), None
Collen Law Associates P.C.
Friedhofer Michael
McDermott Robert M.
TH Contact AG
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