GB2093552A

GB2093552A - Cap for covering an opening

Info

Publication number: GB2093552A
Application number: GB8204208A
Authority: GB
Original assignee: Kienzle Apparate GmbH
Current assignee: Digital Kienzle Computersysteme GmbH and Co KG
Priority date: 1981-02-21
Filing date: 1982-02-12
Publication date: 1982-09-02
Also published as: GB2093552B; DE3106543A1; FR2509497B1; JPS57150860U; FR2509497A1; DE3106543C2

Abstract

A cap (1) is secured within an opening (7) by several detents (10, 11, 12) which project into the opening and engage a complementarily shaped circumferential recess (4) in the cap (1), in order to cover e.g. the head of screw (6) to prevent tampering. <IMAGE>

Description

SPECIFICATION Device for closing and sealing an opening in a constructional part The invention relates to a device for closing and sealing an opening in a constructional part with a cap attributed to the opening and to be releasably retained in the constructional part.

Generally seals are used where as for instance in measuring and counting devices to be calibrated or its measuring means an unauthorized opening or fraudulent tamperings with the object of changing the characteristic of the measured value or of maladjusting the recording or indicating means or where manipulations of counters must be avoided straight away respectively made apparent such seals after such manipulations being unreparably damaged.

The objects to be sealed are usual screw connections of lids or closing caps as well as flange connections between the measuring apparatus and the generators for the measured value attributed thereto, but also unscrewable wall elements provided for adjustments, or openings only, mounting plates as well as individual functional groups arranged outside the actual measuring apparatus. In this connection it is generally usual and also sufficlient to seal just one fastening screw of these parts, which can be made in the most simple case when there are no special claims to the security of the seal by means of a suitable sealing lacquer.Apart from that unusual expensive sealing method in which a hand or wire shaped binding element is stuck through bolts or eyes provided for at the constructional parts to be sealed and a plastically deformable seal is connected thereto, for higher security demands, especially to constructional parts lying outside, a sealing cup is applied to the screw when the screw connection is to be sealed the cup surrounding the screw head is filled up with a lead seal to be squeezed thereby generally also taking up a characterizing stamp or mark (work shop number, symbol of the production site and such like). When the screw heads are sunk it is also known to squeeze on or even to shrink on a seal of plastic material.Furthermore as sealing elements caps of plastic material or wall parallel plates are used which by means of suitable detent means provided thereon may be arrestably connected to the part to be screwed on.

For the sake of being complete it should be mentioned that for sealing elements of plastic material a catching embodiment is generally unavoidable since fastening by impression only gives no sufficient security of the seal because of the possible cold flowing characteristic of the plastic parts, because of material fatigue and a temperature dependent extension.

The last mentioned sealing methods, however, are relatively simple to apply when the sealing position is easily accessible. However, when the adjustments, any changes of the measuring range or when constructional parts or functional groups have to be replaced it is in most cases a difficult problem and entails a lot of difficulties to release such sealing elements. This is especially the case where such a sealing element is arranged in the interior of the apparatus so that there is a danger that due to a relatively unqualified technical manipulation such as for instance the opening of a lead seal unnoticeably other elements of the apparatus are damaged or that parts of the seal drop into the interior of the apparatus which with the clip like sealing elements is rather unavoidable since pawl shaped catching elements will break off when they are destroyed.

Nevertheless lately the above mentioned catching sealing elements of plastic material are used in various embodiments since especially in a production of big series as die-cast parts they are advantageous and in certain applications relatively simple to mount. Also, contrary for instance to lead seals which are provided with characterizing marks by blows which is a rather dubious method for measuring apparatus which have been readily adjusted before the sealing, such plastic seals may be impressed by sealing pincers before being mounted the mounting being normally effected without any tools. Also such sealing elements especially in the form of caps can be inserted in plane shape when the cooperating constructional parts are of a corresponding shape and they can also have a certain signalling effect due to varying colours.

The known caps provided with catches, however, are only to be mounted without any problems in such cases where only openings in housing walls and such like have to be closed and such openings can be extended by a rim protruding internally and/or externally which is unavoidable due to the relatively big hight of such sealing elements. If it is desired to seal a screw connection with such a sealing element or to close the sinking of such a screw it is necessary to provide recesses attributed to the pawls in the counter part to which the constructional part has to be fastened since the pawls must grip round or behind the constructional part to be screwed on, especially when this part is a relatively thin wall so that backward recesses for the detent of the pawl are impossible.When mounting care has also to be taken that the pawls of the cap are immediately opposite the recesses in the part to be screwed on which recesses cannot be of any desired width. This means that the handling of such sealing elements is made more difficult. In other cases, where for instance there are not alterations possible to the constructional part to be fastened, where for instance for reasons of firmness no recesses or cut-outs can be provided concentrically to the screw and where so far the sealing of a screw connection is effected by squeezing a lead or plastic seal into a cup fastened with a screw a relative big hight of design would have to be considered when in similar manner a cap provided with pawls shall be connected with a correspondingly shaped cup, respectively when the opening of the cup shall be closed by a cap.

It was therefore the object of the present invention to avoid the disadvantage mentioned of sealing with a catching sealing element made of plastics and to design a sealing arrangement, which allows for a minimum of mounting expenses, which is applicable to various sealing objects, and in which the sealing element may be removed in a technically "clean" manner.

To solve this problem the invention consists in that at the wall of the opening to be closed and to be sealed and which is preferably cylindrical there are several detents protruding into the opening the front respectively detaining surfaces of which are in one plane transverse to the axis of the opening and wherein at the periphery of the cap there is a surrounding recess attributed to the detents.

The deciding advantages of the solution according to the invention result especially from the fact that the pawls of necessarily thin dimension known from common sealing elements of this kind and the problems resulting from the production and the handling of such sealing elements when mounting them and dismounting them are avoided and that especially due to the very simple shape of the cap as well as due to the idea to attribute rigid detents to the cap and technical expenses as to the form or shape are greatly reduced. It is also essential that the hight of the construction is unusually low. Also important is the fact that the cap according to the invention due to its rotationally symmetrical shape may be mounted independently of its position.

Afurther essential advantage may be seen in that the cap according to the invention may be used either two close openings in thin wall constructional parts but also to close screw connections and sinkings attributed thereto as well as to close the opening of a sealing cup since any measures to apply the cap, that means providing it with detents have to be taken only with respect to the part to be screwed on. For instance due to the small constructional hight a usual sealing cup otherwise used for a lead seal can be closed by a cap according to the invention without any difficulties when the sealing cup, as this is usual, is provided in the sinking of a plane constructional part to be fastened by screws, applying instead of a squeezing seal the sealing closure which is in one plane with the constructional part thereby being also aesthetically advantageous.

In the following the invention shall be explained with reference to the enclosed drawings. In the drawings Figure 1 shows partially in section a sealing element according to the invention in the shape of a cap, Figure 2 is a section of a screw connection with provisions at the constructional parts screwed on to apply the cap according to Figure 1, Figure 3 is a top view of the screw connection according to Figure 2, Figure 4 is a partial section through a constructional part with an opening for adjustment purposes to be closed by a cap according to Figure 1, Figure 5 is a section of a screw connection in which the cap according to Figure 1- is used in connection with a sealing cup.

The sealing element as it is shown in Figure 1 is in the form of a short preferably cylindrical bushing 2 and shall be called a cap 1 which is closed at a front face by a wall 3 at which the sealing mark can be applied with the sealing pincers provided therefore before the cap 1 is mounted. It is essential for the invention that the peripheral surface of the cap 1 is provided with a circular recess 4. A bevelled edge 5 serves for ease for introduction of the cap into the opening to be closed which in the example according to Figure 2 is a sinking 7 attributed to a screw 6.

Within the sinking 7 which is arranged in a constructional part 8 there is a shoulder 9 which serves as a limiting stop to the cap 1 when the latter is mounted and several detents 10,11,12,13, l4attributed to the circular recess 4 of the cap 1 in such a manner that when the cap 1 has been inserted and arrested its front face 3 is essentially a plane surface with the surface of the constructional part 8. Openings, one of which has been given with reference numerl 15, serve to shape out the detents 10 to 14 while 16 is a projection serving to fasten the constructional part 8.

It should be mentioned that it is advantageous when the cap 1 is slightly biggerto higher than the openings into which it is to be introduced.

In the embodiment according to Figure 4 in a constructional part 17, which may be for instance a housing wall, a mounting or covering plate there is an opening 18 which gives access to an adjustment shaft 19 for instance of a potentiometer. Also in this case in similar manner as already described in connection with the embodiment shown in Figure 2 and 3 within the opening 18 attributed to the cap 1 there are detents of which three, 20,22,22, have been shown. Also there is a shoulder 23 which is subdivided into individual segments due to the shape of the detents for die-cast purposes which does not detrimentally influence its function as a stop catch. Naturally the cap 1 may be provided with a rim at its periphery which instead of the shoulder 9 resp. 23 serves as a stop catch.

The embodiment according to Figure 5 shows that the detents attributed to the cap 1 are not shaped on the constructional part 25 to be connected to a housing 24 but that additionally a sealing cup 26 may be applied which is known manner together with a screw 27 may be fastened with the constructional part 25. In this case the detents attributed to the cap 1 are arranged within the opening of the sealing cup 26 so that the front and detaining surfaces are in one plane transverse to the axis of the sealing cup, however, not necessarily at the same distance of each other. As may be seen from Figure 5 the sealing cup 26 may be arranged in a sunk position for instance replacing a usual lead seal arrangement so that a plane surface together with the part 25 is achieved. However, it can also be applied with any known screw connection in a set-up manner, various forms of caps being possible not only cylindrical caps. It is essential that as in this embodiment neither at one nor at the other of the constructional parts 24 and 25 to be screwed together any modifications have to be made with a view to sealing.

Claims

1. Device for closing and sealing an opening in a constructional part with a cap attributed to and arrestably retained in this part, characterized in that at the wall of the preferably cylindrical opening (7) to be closed and sealed there are several detents (10 to 14) protruding into the opening and of such shape that their front respectively detaining surface are arranged in a plane tranverse to the axle of the opening (7) and that at the periphery of the cap there is a surrounding recess (4) attributed to the detents (10 to 14).

2. Device for closing and sealing an opening in a constructional part substantially as described herein with reference to the accompanying drawings.