阅读说明：本技术 用于插入式连接的保护装置 (Protective device for plug-in connection ) 是由 珍妮特·利尼格尔 罗伯特·施密特 佛朗哥·费拉多 戈尔德·贝希特 维利·胡维勒 于 2018-12-17 设计创作，主要内容包括：本发明涉及一种保护装置(10),用于连接器(8)和插口(7)之间的可释放的插入式连接(5)的至少一个部件,所述插口(7)至少部分地被布置在现场装置(3)的壳体(2)上或所述壳体(2)中。根据本发明所述的保护装置(10)包括：至少一个第一半壳(11a)和第二半壳(11b),所述第二半壳(11b)至少部分地与所述第一半壳(11a)互补,其中两个半壳(11a、11b)以如下方式设计,即：使得当所述两个半壳(11a、11b)彼此结合时限定内部容积(V)并且至少部分地封围至少所述连接器(8)；至少一个第一通孔(12),所述至少一个第一通孔(12)用于使所述连接器(8),或者所述连接器(8)和固定到所述连接器(8)的电缆(9)穿过,以进入到所述保护装置(10)的所述内部容积(V)中；至少一个固定单元(13),所述至少一个固定单元(13)用于将所述保护装置(10)以可释放的方式固定到所述壳体(2)；以及至少一个连接单元(13),所述至少一个连接单元(13)用于将所述两个半壳(11a、11b)以可释放的方式彼此连接。(The invention relates to a protective device (10) for at least one component of a releasable plug-in connection (5) between a connector (8) and a socket (7), wherein the socket (7) is arranged at least partially on a housing (2) of a field device (3) or in the housing (2). The protection device (10) according to the invention comprises: at least one first half-shell (11a) and a second half-shell (11b), the second half-shell (11b) being at least partially complementary to the first half-shell (11a), wherein the two half-shells (11a, 11b) are designed in such a way that: such that when the two half-shells (11a, 11b) are joined to each other, an internal volume (V) is defined and at least partially encloses at least the connector (8); at least one first through hole (12), said at least one first through hole (12) being used for passing said connector (8), or said connector (8) and a cable (9) fixed to said connector (8), in order to enter into said inner volume (V) of said protection device (10); at least one fixing unit (13), said at least one fixing unit (13) being intended to fix said protection device (10) to said housing (2) in a releasable manner; and at least one connecting unit (13), the at least one connecting unit (13) being used for connecting the two half-shells (11a, 11b) to each other in a releasable manner.)

1. A protection device (10) for at least one component of a plug-in connection (5), in particular a releasable plug-in connection (5), between a plug (8) and a socket (7), the socket (7) being arranged at least partially on a housing (2) or in the housing (2), in particular at least partially on a housing (2) of an electronics unit (1) or in the housing (2), preferably at least partially on a housing (2) of a field device (3) or in the housing (2),

the protection device (10) comprises:

at least a first half-shell (11a) and a second half-shell (11b),

wherein the second half-shell (11b) is at least partially complementary to the first half-shell (11a) and

the two half-shells (11a, 11b) are designed in such a way that: so as to define an internal volume (V) and at least partially surround at least the plug (8) when the two half-shells (11a, 11b) are assembled,

at least a first channel (12), said at least a first channel (12) being used for passing through said plug (8), or said plug (8) and a cable (9) fixed to said plug (8), to enter into said internal volume (V) of said protection device (10),

at least one fixing unit (13) for fixing a protective device (10) to the housing (2), in particular to the housing (2) in a releasable manner, and

at least one assembly unit (13), the at least one assembly unit (13) being used for assembling the two half-shells (11a, 11b) to each other, in particular in a releasable manner.

2. The protection device (10) as claimed in claim 1,

wherein the first channel (12) is part of at least one of the two half-shells (11a, 11 b).

3. The protection device (10) of claim 1 or 2,

wherein the first channel is an opening, in particular a circular opening, in the wall of one of the two half-shells (11a, 11b), or

Wherein each of the two half-shells (11a, 11b) has a cutout, in particular a cutout which is also embodied, in the edge region of the housing wall, wherein the two cutouts are embodied, in particular complementarily embodied with respect to one another, in such a way that: such that in the assembled state of the half-shells the two cutouts form the first channel (12).

4. The protection device (10) according to at least one of the preceding claims,

wherein the fixing unit (13) is part of at least one of the two half-shells (11a, 11 b).

5. The protection device (10) according to at least one of the preceding claims,

wherein the fixing unit (13) is embodied at least partially complementary to the housing (2) in the region of the socket (7).

6. The protection device (10) according to at least one of the preceding claims,

wherein the fixing unit (13) is implemented in such a way that: so that the protective device (10) can be fixed to the housing (2) by force and/or form locking.

7. The protection device (10) according to at least one of the preceding claims,

wherein the assembly unit (14) is a unit for producing a screw connection, a latching mechanism or a lead seal between the two half-shells (11a, 11b) and one another.

8. The protection device (10) according to at least one of the preceding claims,

wherein the plug-in connection (5) is an M12 plug-in connection.

9. The protection device (10) according to at least one of the preceding claims,

wherein at least one of the half-shells (11a, 11b) has a rib structure (16), in particular a rib structure (16) in the inner region.

10. The protection device (10) according to at least one of the preceding claims,

wherein the protection device (10) comprises an opening (17), through which opening (17) moisture can leave the inner volume of the protection device.

11. The protection device (10) according to at least one of the preceding claims,

wherein at least one of the two half-shells (11a, 11b) is made of a transparent material.

12. The protection device (10) according to at least one of the preceding claims,

wherein the thickness of the shell wall of at least one of the two half shells is variable at least in sections, in particular wherein the thickness of the shell wall is reduced in a predeterminable portion (15).

13. The protection device (10) according to at least one of the preceding claims,

wherein the first channel (12) is arranged in the region of a housing wall formed by the half-shells (11a, 11b) on the side opposite the fixing unit (13).

14. The protection device (10) according to at least one of claims 1 to 13,

wherein the first channel (12) is arranged in the region of the following housing walls: is formed by the half-shells (11a, 11b) and extends at a predeterminable angle to a plane parallel to the fixing unit (13), in particular perpendicularly to a plane parallel to the fixing unit (13).

15. The protection device (10) according to at least one of the preceding claims,

comprises at least two channels (12a, 12b), preferably three channels (12a to 12c), wherein the first channel (12a) is arranged in the region of a housing wall formed by the half-shells (11a, 11b) on the side opposite to the fixing unit (13); wherein a second channel (12b) is arranged in the region of a housing wall which is formed by the half-shells (11a, 11b) and which extends at a predetermined angle to a plane parallel to the fixing unit (13), in particular extends perpendicularly to a plane parallel to the fixing unit (13); and wherein preferably a third channel (12c) is arranged in the region of the housing wall formed by the half-shells (11a, 11b) and extending perpendicularly to a plane parallel to the fixing unit (13), and the third channel (12c) is opposite to the second channel (12 b).

Technical Field

The invention relates to a protective device for a plug-in connection between a plug and a socket. In particular, the plug-in connection is a releasable plug-in connection. The socket is arranged at least partially on or in a housing of an electronic device, preferably a field device, for example.

Background

The field device is used to monitor and/or determine at least one process variable, e.g., chemical or physical, of the medium. In the context of the present invention, in principle, all measuring devices are referred to as field devices, which are applied in the vicinity of the process and transmit or process-related information and, therefore, also remote I/O, radio adapters, and in general electronic components, which are arranged at the field level. A large number of such field devices are manufactured and sold by companies from the endrice and Hauser group (Endress + Hauser).

For example, the field device can be a fill level measuring device, a flow meter, a pressure measuring device and a temperature measuring device, a pH measuring device and/or a pH redox potential measuring device, and even a conductivity measuring device, which is used to record process variables, such as fill level, flow, pressure, temperature, pH value, redox potential or conductivity of the medium. The measurement principles supporting different types of field devices are sufficiently known from the prior art and are not explained in detail here. In the case of flow meters, such flow meters are, in particular, coriolis flow meters, ultrasonic flow meters, vortex flow meters, thermal flow meters and/or magneto-inductive flow meters. The filling level measuring device is then embodied in particular as a microwave filling level measuring device, an ultrasonic filling level measuring device, a time-domain reflectometry filling level measuring device (TDR), a radiometric filling level measuring device, a capacitive filling level measuring device, a conductive filling level measuring device and/or a temperature-sensitive filling level measuring device. In the case of pressure measuring devices, such measuring devices preferably relate to absolute pressure measuring devices, relative pressure measuring devices and differential pressure measuring devices, while temperature measuring devices often have thermocouples or temperature-dependent resistors for determining the temperature.

The field device comprises a sensor unit which is at least partially and at least at times in contact with the process and an electronics unit, for example for signal recording, evaluation and/or feeding. At least the electronics unit of the field device is usually arranged in a housing and usually has at least one contact element. There are field devices in which an electronics unit is arranged together with a sensor unit. Alternatively, however, the electronics unit and the sensor unit can also be embodied in the form of separate units.

In the case of the at least one contact element, this is usually a plug-in socket for contacting the field device with an additional unit, for example an external unit such as a process control station, a power supply unit or even a sensor unit of the field device, via a cable which is equipped with a plug complementary to the socket.

There are various embodiments for the housing and plug connection for contacting the electronic unit, depending on the type of field device, and thus on the process variables to be determined and/or monitored and/or on the intended application or use of the field device. In this case, different, in particular application-specific requirements play a decisive role. For field devices which are also operated in explosion-hazard areas, they must meet high safety requirements, for example with regard to explosion protection. In this respect, different types of explosion protection and explosion zones are distinguished, wherein different requirements are set forth, for example, in the european ATEX directive or the north american NEC specification and the IEC or NEC standards based thereon.

For example, it is of interest to safely prevent the formation of sparks or at least to ensure that the sparks generated at the time of a fault have no influence on the surrounding environment.

With regard to plug-in connections for various applications, relevant considerations include whether the plug-in connection is protected against the intrusion of foreign bodies, in particular solid particles (e.g. dust), whether a mechanical impact test is possible, and in particular, whether there is still protection against the intrusion of foreign bodies after a mechanical impact. In particular, the plug-in connection must not break upon application of an external force (e.g. 4J or 7J).

Disclosure of Invention

The object of the invention is to implement a plug-in connection in such a way that: so that it has a high mechanical stability.

The object is achieved by a protective device for at least one component of a plug-in connection, in particular a releasable plug-in connection, between a plug and a socket, which socket is arranged at least partially on or in a housing, in particular at least partially on or in a housing of an electronic unit, preferably of a field device.

The protective device according to the invention comprises at least a first half-shell and a second half-shell, wherein the second half-shell is at least partially complementary to the first half-shell, wherein the two half-shells are embodied in such a way that: such that they define an internal volume when assembled and at least partially enclose at least the plug, or the plug and the socket, at least a first passage for passing the plug, or the plug and a cable fixed to the plug, into the internal volume of the protection device,

at least one fixing unit for fixing, in particular releasably fixing, the protective device to the housing, and

at least one assembly unit for assembling the two half-shells to one another, in particular in a releasable manner.

The protective device thus at least partially surrounds the plug-in connection. In particular, the protection device can advantageously be placed subsequently on an existing, in particular releasable, plug-in connection, in particular the protection device is also releasably placed. In this way, the protection device can be removed at any time, for example when a plug-in connection is to be disconnected. However, it is also advantageous to be able to replace the protective device only individually. Preferably, the plug and socket are first connected together and then the protection device is installed for protecting the plug-in connection. In this case, not only a mechanical protection function but also protection against the intrusion of foreign bodies (e.g. dust particles) into the plug-in connection can be provided.

The two half-shells are preferably made of metal, plastic, in particular thermoplastic, or even synthetic resin.

The protection device provides increased security of the plug-in connection. In the case of a plug-in connection which can be mounted to the housing of the field device, the field device is preferably designed to operate in an atmosphere which is at risk of explosion. For example, the application of the field device according to the ignition protection type dust-Ex can be ensured. Electrical devices implemented according to this protection class are based, for example, on housing protection to ensure that no dust can enter the housing. Dust can cause an explosion, for example, when associated with an ignition source (e.g., electrical contacts) disposed in the housing. Another requirement for use of the device in explosion hazard environments relates to shock or impact resistance: the housing must not be damaged by impact and therefore by external forces. Therefore, it is necessary to ensure a sufficient closing state and mechanical strength, which is also achieved by applying the protection device of the present invention.

One embodiment provides that the channel is part of at least one of the two half-shells.

Advantageously, the first channel is an opening, in particular a circular opening, in the wall of one of the two half-shells. Alternatively, however, it is also possible to choose each of the two half-shells to have a cutout, in particular a likewise embodied cutout, in the edge region of the housing wall, wherein the two cutouts are embodied, in particular complementarily embodied with respect to one another, in such a way that: such that the two cutouts form a first channel in the assembled state of the half shells. In the assembled state of the protective device, the two half-shells then form an opening, in particular a circular opening, which serves, for example, as a passage. In the case of a plurality of channels, the additional channel can be implemented either similarly to the first channel or differently from the first channel.

Another embodiment comprises that the fixing unit is part of at least one of the two half-shells. The fastening unit can be designed in particular in such a way that it can be placed or fastened on one of the two half-shells. Alternatively, it is an option that at least a first part of the fixing unit can be placed or fixed on the first half-shell and at least a second part of the fixing unit can be placed or fixed on the second half-shell.

Advantageously, the fastening unit is embodied at least partially complementary to the housing in the region of the socket. In particular, the fixing unit is implemented in such a way that: such that the protective device can be inserted onto a portion of the housing or can be fixed or placed on a portion of the housing.

It is also advantageous if the fastening unit is embodied in such a way that: such that the protection device can be fixed to the housing by force interlocking and/or shape interlocking. The force-locking and/or form-locking fastening of the protective device to the housing can provide increased mechanical stability, in particular increased mechanical stability against mechanical impacts on the plug-in connection or the protective device.

For example, the fixing unit can be implemented in at least one part of at least one component of the protection device, in particular in at least one part of at least one of the two half-shells, which is complementary to the part of the housing on which the protection device is fixed. In particular, the portion of the protection device is implemented in an inner region complementary to an outer region of the portion of the casing.

One embodiment comprises that the assembly unit is a unit for producing a screw connection, a latching mechanism or a lead seal between the two half-shells to one another. In particular, the protection device can be implemented in such a way that: so that the two half-shells, while being assembled by the assembly unit, cause the half-shells to be fixed to the housing. This can be achieved in particular by suitably positioning the fixing unit relative to the assembly unit.

In the case of a screw connection assembly which can be produced by an assembly unit, the assembly unit comprises, for example, at least one screw and at least one thread in at least one component of the protective device. Preferably, such an assembly unit comprises at least two screws arranged on opposite sides of the half-shells and intended for assembling the two half-shells in a releasable manner with respect to each other.

In another embodiment, the plug-in connection is an M12 plug-in connection.

One embodiment provides that at least one of the half shells has a rib structure, in particular in the inner region. The rib structure serves to increase mechanical stability.

In another embodiment, the protective device comprises an opening through which moisture can leave the inner volume of the protective device. Thus, moisture reaching the inner volume of the protection device can escape through the opening.

Advantageously, at least one of the two half-shells is made of a transparent material. On the one hand, in this way it can be checked whether the plug is correctly inserted into the socket. In addition, in given cases it can be ensured that despite the application of the protective device, the light-emitting elements (for example LEDs) located in the region of the plug-in connection or on the housing remain visible to the outside. Such LEDs are often used on electronic units, in particular field devices, for example as a signal for certain functions of the electronic unit or field device, even for indicating the presence of a defect.

It is also advantageous if the thickness of the housing wall of at least one of the two housing halves is variable at least in sections, in particular if the thickness of the housing wall decreases in a predeterminable portion. This is particularly advantageous when the half-shells are made of a transparent material. In this case, the thickness of the housing wall can be selected in sections in such a way that: the half-shells are used as light guides for light-emitting elements used in the region of the plug-in connection or in the region of the housing, and to improve the visibility of the light-emitting elements to the outside. The housing wall of the half-shell is then embodied in particular in such a way that: such that in a state in which the protective device is fixed on the housing, a portion of the housing wall having a reduced thickness (or an increased thickness) is arranged in the region of the light-emitting element.

A preferred embodiment of the protection device comprises that the first channel is arranged in the region of a housing wall formed by the half-shell on the side opposite the fixing unit. This arrangement of the channels is suitable for plug-in connections in which a straight plug is used.

Conversely, a preferred alternative embodiment of the protective device comprises that the first channel is arranged in the region of the following housing wall: formed by the half shells and extending at a predeterminable angle to a plane parallel to the fixing unit, in particular perpendicularly to a plane parallel to the fixing unit. This arrangement of the channels is then particularly suitable for curved plugs, in particular plugs formed at right angles.

In a particularly preferred embodiment, the protective device finally comprises at least two, preferably three channels, wherein a first channel is arranged in the region of the housing wall formed by the half-shell on the side opposite the fixing unit, wherein a second channel is arranged in the region of the housing wall formed by the half-shell and extending at a predeterminable angle to a plane parallel to the fixing unit, in particular extending perpendicularly to a plane parallel to the fixing unit, and wherein preferably a third channel is arranged in the region of the housing wall formed by the half-shell and extending perpendicularly to a plane parallel to the fixing unit, opposite the second channel. The arrangement of a plurality of channels realizes that the same protection device can be universally used for a straight plug and a bent plug. In the case of three channels, it is particularly advantageous, because of the symmetry thus produced, to be able to produce the two half-shells by means of the same tool. This in turn significantly reduces manufacturing complexity, and the manufacturing costs associated therewith.

The object of the invention is furthermore achieved by a field device, in particular by a process measurement technology field device, comprising a sensor unit and an electronics unit which are arranged at least partially in a housing, and by a protective device according to the invention in accordance with at least one of the embodiments described above.

Drawings

The invention will now be explained in more detail on the basis of an example of an embodiment shown in the drawings, in which the figures are as follows:

figure 1 is a schematic view of an electronic unit arranged in a housing with a plug-in connection,

figure 2 is an embodiment of the protection device for a straight plug of the invention,

fig. 3 is an embodiment of the protection device for a 90 degree bend plug of the present invention, and

fig. 4 is a perspective view of the two half-shells of the protection device.

Detailed Description

In the drawings, like elements are provided with like reference numerals.

Fig. 1 shows a schematic view of an electronics unit 1 arranged in a housing 2. For example, but not necessarily, the electronic unit 1 is an electronic unit 1 of a field device 4, which comprises a sensor unit 3 (dashed line) connected to the electronic unit 1.

The electronics unit 1 is connected via a plug-in connection 5 to an external unit 6, which external unit 6 can be, for example, a process control station. Instead of the external unit 6, the electronic unit 2 can be connected to another device (not shown) via a plug-in connection 5. The other devices that can be connected with the electronic unit 2 via the means consisting of the cable 9 and the plug-in connection 5 can be any devices.

A socket 7 of the plug-in connection 5 is arranged on the housing 2. For this purpose, the housing 2 comprises a projection 2a, in which projection 2a the socket 7 is accommodated. Of course, other embodiments of the housing 2 and the socket 7 are also possible as options. A plug 8 complementary to the socket 7 is inserted into the socket 7. The plug 8 terminates a cable 9, said cable 9 likewise being connected to the external unit 6. This example shows a three-pole plug-in connection. Of course, many other plug connections can also be used in the context of the present invention, in particular plug connections with some other number of poles can also be used.

In order to increase the mechanical stability of the plug-in connection 5, the invention provides for the use of a protective device 10. In particular in the case of an application of the electronic unit 1 in an explosion-hazard area, the plug-in connection 5 must be able to withstand mechanical shocks. The plug-in connection 5 must in particular not be broken by the application of an external force. Furthermore, after a mechanical impact, the plug-in connection must remain protected against the intrusion of foreign bodies.

The following figures describe by way of example a preferred embodiment of the protection device 10 of the present invention.

Fig. 2 shows a first exemplary embodiment of a protective device 10 for a plug-in connection 5 with a straight plug 8. The protection device 10 comprises two mutually complementary half-shells 11a and 11b which can be assembled in a mutually releasable manner by means of an assembly unit 14. In the assembled state, the two half-shells 11a and 11b form an inner volume V, such as shown in fig. 2b, which encloses the socket 7 and the plug 8 of the plug-in connection 5.

In the embodiment shown here, the assembly unit 14 comprises means for producing a threaded connection assembly. The two half-shells 11a and 11b have two mutually complementary holes 14a, 14a ' [ only one visible here ], said holes 14a, 14a ' being arranged on opposite sides and being equipped with a thread [ not visible ], into which a screw 14b, 14b ' [ also only one visible ] can be screwed for establishing the assembly of the two half-shells 11a and 11 b.

In the present case, both a form-locking and a force-locking fastening of the protective device 10 to the housing 2 can be achieved by means of the fastening unit 13. As best shown in fig. 2b, the two half-shells 11a and 11b are in each case embodied as parts 13a, 13a' complementary to the part 2a of the housing 2 [ in fig. 2b only half-shell 11b is shown ], the protective device 10 being attached or fixed to the part 2 a.

Furthermore, the two half-shells 11a and 11b have a first passage 12a for the insertion of the plug 8 into the inner volume V of the protective device 10. In the example shown here, each of the two half-shells 11a, 11b comprises for this purpose a cutout in the edge region of the housing wall, wherein the two cutouts are embodied in the following manner and are in particular embodied complementarily with respect to one another in such a manner that: so that they form a first channel 12a in the assembled state of the half-shells 11a, 11 b. In the example of fig. 2, the first channel 12a is arranged in the region of the housing wall formed by the half shells 11a, 11b on the side opposite the fixing unit 13.

As shown in fig. 2, said protection device 10 comprises, in addition to the first channel 12a, a second channel 12b and a third channel 12c, each of which extends perpendicularly to a plane E parallel to the fixed unit 13, on opposite sides of the shell wall of the protection device 10, or to the plane E parallel to the fixed unit 13, on the shell walls of the two half-shells 11a, 11b, although not absolutely necessary.

In the example of a straight plug connection of the invention, no plug 8 or connecting cable 9 is guided through any of the two additional channels 12b, 12 c. In another embodiment, the second channel 12b and/or the third channel 12c can also be omitted.

In fig. 3 an embodiment of a protection device 10 with a 90 degree bent plug 8 is shown. As shown in fig. 2, fig. 3a is a perspective view of the protective device 10, while a cross-sectional view is provided in fig. 3 b. For fig. 3, the reference numerals already explained in connection with fig. 2 will not be discussed again in detail. In contrast to fig. 2, fig. 3 shows the plug 8 being introduced into the inner volume V of the protection device 10 through the third channel 12 c. In the case of the embodiment of fig. 3, the first and second channels 12a, 12b are optional and can be omitted in other embodiments. Furthermore, it is likewise possible to choose to guide the bent plug 8 through the second channel 12b in such a way that: so that the first 12a and third 12c channels remain unused.

Finally, fig. 4 shows a perspective view of the two half-shells 11a and 11b of the protective device 10. Fig. 4a shows the first half-shell 11a in the following manner, namely: so that the outer region of the half-shell 11a is visible. In contrast, for the second half-shell 11b shown in fig. 4b, the inner region of the half-shell 11b is shown. Again, three channels 12a to 12c of the protection device 10 are provided, which are formed by mutually complementary cut-outs in the wall of the two half-shells 11a and 11 b. The embodiment of the protection device 10 with three channels 12a to 12c has the advantage that the protection device 10 can be used universally for straight plugs and also for curved plugs 8. Furthermore, such a protection device 10 is characterized by a high degree of symmetry. For example, advantageously, the three channels 12a to 12c of the two half-shells 11a and 11b can be made with the same tool.

The two half-shells 11a and 11b of fig. 4 have in each case a rib structure 16 in their inner region, which rib structure 16 is shown in fig. 4 b. This serves to increase the mechanical stability of the protective device 10. Furthermore, the protective device 10 of fig. 4 has an opening 17, through which opening 17 moisture that has penetrated into the inner volume V of the protective device 10 can escape from the protective device 10. In the present example, the opening 17 is in the half-shell 11a and/or 11 b. Thus, for example, the opening 17 in the housing wall of one of the two housing halves 11a, 11b is an option, and there are also embodiments of the housing halves 11a and 11b with two mutually complementary passages in the region of the outer wall, which form the opening 17 in the assembled state of the two housing halves 11a and 11 b.

Furthermore, the thickness d of the shell walls of the two half-shells 11a and 11b is reduced in the portion 15. This is particularly advantageous when the half-shells 11a and 11b are produced from a transparent material, such as should be assumed for the example of embodiment shown in fig. 4. Due to this measure, it can be ensured that despite the protective means 11 being applied to the housing 2, at least one light-emitting element (not shown) applied in the region of the plug-in connection 5 or the housing 2 remains visible from the outside. The half-shells 11a and 11b then act as light conductors in the portion 15 for the light emitted from the light-emitting elements and conduct the light appropriately to the observer.

List of reference numerals

1 electronic unit

2 casing

2a parts of the housing

3 sensor unit

4 field device

5 plug-in connection

6 external unit

7 socket

8 plug

9 electric cable

10 protective device

11a, 11b first and second half-shells

12,12a-12c channels

13 fixing unit

13a half-shell portion

14 Assembly unit

14a having an internally threaded bore

14b screw

15 reduced thickness portion

16-rib structure

17 opening

V internal volume