DE20312374U1 - Safety switching system for use with an air ventilation system has plug removal protection mechanism - Google Patents

Abstract

The housing has a switch (50) that provides a connection between a plug (49) and the output pins (43,44). The plug is protected against removal by a hinged lever bracket (60). When this is moved to the blocking position, it also operates a safety switch (58) that enables the main switch.

Description

BOEHMERT & BOEHMERT

LAW FIRM

Boehmert & Boehmcit ■ P.O.B. 1071 27-D-28071 Bremen

German Patent and Trademark Office Zweibrückenstrasse 12

80297 Munich

DR. ING. KARL BOEHMERT, PA(im-im)
DIPL.-ING. ALBERT BOEHMERT, Pa{1902-1993)

WILHELM J. H. STAHLBERG, Attorney Bremen

DR-ING. WALTERHOORMANN,pa·.b™™

DIPL-PHYS. DR. HEINZGODDAR, pa·,Mond™

DR-ING. ROLAND LIESEGANG, PA·. Some

WOLF-DIETER KUNTZE, Attorney Bremen, Ali™«

DIPL-PHYS. ROBERTMÜNZHUBER,pa(1S33-19K)

DR. LUDWIG KOUKER, Attorney Bremen

DR. (CHEM.) ANDREAS WINKLER, pa·, Bremen

MICHAELA HUTH-DERIG, Attorney at Law Munich

DIPL-PHYS. DR. MARIONTÖNHARDT, PA·,Dfo-eldorf

DR. ANDREAS EBERT-WEIDENFELLER, Attorney Bremen

DIPL-ING. EVALIESEGANG, PA·.Mündwn

DR. AXEL NORDEMANN, LAWYER Berlin

DIPL-PHYS. DR. DOROTHEE WEBER-BRULS, pa·,Frmkfiin

DIPL-PHYS. DR. STEFANSCHOHE, pa·.Munich

DR-ING. MATTHIAS PHILIPP, PA·. B.defdd

DR. MARTIN WIRTZ, Düoeldorf attorney

DR. DETMAR SCHÄFER, Attorney Bremen

DR. JAN BERND NORDEMANN, LLM., Berlin Attorney
DR. CHRISTIAN CZYCHOWSKI, Berlin Attorney
DR. CARL-RICHARD HAARMANN, ra Manchen
DIPL-PHYS. CHRISTIAN W. APPELT, pa·. Munich
DIPL-PHYS. DR-ING. UWE MANASSE, PA·. Bremen
DIPL-PHYS. DR. THOMAS L. BITTNER, PA-. Berlin
DR. VOLKER SCHMITZ, M. Juris (Oxford), ra Manchen, p™
DIPL-BIOL. DR. JAN B. KRAUSS, pa·, Berlin

PA - Patent Attorney

RA - Attorney/Attorney at Law

• - European Patent Attorney

° - Mfiitrc and Law

° - Law License

O - Diplome d"Etudes Approfondies en Conception de Produits et

innovation

All access to representation before the European Ministry of Justice, Alicante
Profusion»] RepreienUtion it the Community Trademark Office, Alicante

PROF. DR. WILHELM NORDEMANN, LAWYER Pot*Um

DIPL.-PHYS. EDUARD BAUMANN, I

DR.-ING. GERALD KLOPSCH, &rgr;

DIPL-ING. HANS W. GROENING, &rgr;&agr;·. Munich

DIPL-ING. SIEGFRIED SCHIRMER, pa·. Bielefeld

DIPL.-PHYS. LORENZ HANEWINKEL, pa·, P.de*oin

DIPL-ING. ANTON FREIHERR RIEDERER V. PAAR, pa·.

DIPL-ING. DR. JAN TÖNNIES, pa RA Kid

DIPL-PHYS. CHRISTIAN BIEHL, pa·, Kiel

DR. ANKE NORDEMANN-SCHIFFEL, Attorney-at-law,

DR. KLAUS TIM BRÖCKER, ra B=Ib.

DR. ANDREAS DUSTMANN, LLM., RA Poudun

DIPL-ING. NILS T. F. SCHMID, PA's Munich, p™

DR. FLORIAN SCHWAB, LLM., RA-. Some",

DIPL-BIOCHEM. DR. MARKUS ENGELHARD, pa Munich

DIPL.-CHEM. DR. KARL-HEINZ B. METTEN, pa·, Frankfurt

PASCAL DECKER, ra Bertin

DIPL-CHEM. DR. VOLKER SCHOLZ. PA Brem«

DIPL.-CHEM. DR. JORK ZWICKER, pa Mönchen

DR. CHRISTIAN MEISSNER, RA Mund™

DIPL-PHYS. DR. MICHAEL HARTIG, pa Munich

In cooperation with DIPL-CHEM. DR. HANS ULRICH MAY, pa·, m

Your sign
Your ref.

Your letter of

New registration (utility model)

Our sign
Our ref.

G60048

Bremen,

08.08.2003

Armin Bauer

Middle Way

73275 Ohmden Erich Gärtner

Pestalozzistrasse 36

10627 Berlin

Safety plug for an exhaust air system

10 The invention is in the field of safety plug devices which close or interrupt a power supply line for an exhaust air system for removing air from a room depending on a state of a supply air system in the room.

- 72,624 -

Hollerallee 32 · D-28209 Bremen · P.O.B. 10 71 27 · D-28071 Bremen · Telephone +49-421-34090 · Fax +49-421-3491768

MUNICH - BREMEN - BERLIN - lSü2s£l,D0RF -

JkiEL - 4"I)ERBi)RNl- LANDSHuf - HÖHEnJiRCHEN - ALICANTE - PARIS - SHANGHAI · ······ ···

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BOEHMERT & BOEHMERT· "··' ..* \. ^#

A safety plug is placed between a plug of the power supply line of the exhaust air system and a socket of a power supply system, for example a 220 V power supply network.

The exhaust air system, the power supply plug of which is inserted into the safety plug during use, can in particular be a cooker hood, an exhaust air dryer, a gas boiler, an exhaust air fan, an extraction system or a central vacuum cleaner system.

Such an exhaust air system is known, for example, from the publication DE 100 28 333 and is used in conjunction with exhaust air systems in rooms with access to a fireplace, for example an open fireplace, a tiled stove, a charcoal stove, an oil stove, a gas boiler or the like. With the help of the exhaust air system, air is transported from the room to the outside. The safety circuit arrangement is used to control the tapping and supply of electrical voltage for the operation of the exhaust air system.

Since carbon dioxide and carbon monoxide are produced in rooms with a fireplace when fuel is burned, transporting air from the inside of the room to the outside using the exhaust air system can lead to dangerous situations for people in the room. The well-known safety circuit arrangement ensures that the exhaust air system can only be operated if a supply of fresh air is guaranteed via an air supply system. The air supply system can be, for example, a supply air flap or a window.

An open supply air system in living spaces means that air can flow in from outside. Residents of the residential building find this unpleasant, for example in winter, because cold air flows in from outside. As a result, cases have occurred in which the voltage supply of the exhaust air system, which is linked to the safety circuit arrangement, was manipulated to bypass the safety circuit arrangement in order to

BOEHMERT & BOEHMERT· ··

air system even when the supply air system is closed. However, this leads to an increased safety risk.

The publication DE 202 10 684 discloses a safety plug device of the type mentioned above. The safety plug device has a safety device which can be moved between an open position, in which the plug of the power supply line of the exhaust air system can be inserted into the plug receptacle/removed from the plug receptacle, and a closed position, in which removal of the plug of the power supply line from the plug receptacle is prevented.

This safety plug device makes manipulation for the purpose of circumventing the safety switching arrangement more difficult, but the disclosed device does not effectively prevent the plug of the power supply line from becoming loose due to external influences or due to vibrations acting on the plug device.

The object of the invention is to provide an improved safety plug device of the type mentioned at the outset, with which the above-mentioned disadvantages are effectively eliminated and the risk of unwanted manipulation, which leads to a safety risk, is also minimized.

This object is achieved according to the invention in a safety plug device according to claim 1.

The invention includes the idea of holding the plug in the essentially fully inserted position in a secure electrical and mechanical connection with the aid of locking means when the safety device is in a closed position. In the secured state, the plug cannot come loose from the plug receptacle, even due to external forces. A fully inserted position of a plug in the receptacle of the safety plug device is understood to mean a position in which the contact pins of the plug are essentially completely inserted into the connection sockets of the plug receptacle of the safety plug device. In this position, an electrical contact is made between the contact pins of the plug and the

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Receptacles of the safety plug-in device are designed. In this case, the contact surfaces between the contact pins and the receptacles have an optimal surface area and contact resistance is minimized.

A significant advantage achieved by the invention over the prior art is that the plug of the power supply line of the exhaust air system is held in a connection with the aid of the locking means of the safety device in such a way that unintentional loosening of the plug is impossible. This applies equally to forces acting unintentionally on the plug and the plug receptacle of the safety plug device as well as to targeted attempts at manipulation that fail. In both cases, it is ensured that there is no loose contact between live parts of the plug of the power supply line and the plug receptacle of the safety plug device. If there is a "loose" contact between the connection sockets of the receptacle of the safety plug device and the connection contacts of the plug of the power supply line of the exhaust air system, sparks can fly or an arc can form when the exhaust air system is operated. Both effects are associated with the development of strong heat, which can destroy the plug and/or the safety plug device and lead to a fire. The invention eliminates or greatly reduces these risks.

An expedient further development of the invention provides that the safety device comprises a pivotably mounted bracket as a locking means, which, in the closed position of the safety device, touches the plug of the power supply line inserted into the plug receptacle from a side facing away from the plug receptacle. A pivotable bracket represents a particularly stable and easy-to-manufacture locking means.

An embodiment of the invention which can be implemented with little effort provides that the safety device comprises a locking band which spans the plug of the power supply line as a locking means, which, in the closed position of the safety device, locks the plug of the power supply line inserted into the plug receptacle.

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supply cable from the side facing away from the plug receptacle, with one side of the locking band being releasably attached.

A preferred development of the invention which can be implemented robustly using simple mechanical means is created in that the safety device comprises guides with bores and a locking pin which can be displaced essentially perpendicularly to an insertion direction of the power supply plug into the plug receptacle as a locking means, which is held in the bores in the closed position of the safety device and touches the plug of the power supply line inserted into the plug receptacle from the side facing away from the plug receptacle.

An embodiment of the invention that offers little surface area or points of attack for attempts at manipulation is created in that the plug receptacle is designed as a Schuko plug receptacle with two opposing guide grooves for receiving guide projections of the plug of the power supply line designed as a Schuko plug and the locking means comprise two locking bolts that engage laterally in the plug receptacle and that, in the closed position of the safety device, each engage behind the guide projections.

An embodiment of the invention prepared to accommodate plugs of different shapes and sizes provides that the locking means comprise a deformable region which is deformed in the closed position and exerts a restoring force on the plug of the power supply line which acts essentially in the direction of insertion of the plug of the power supply line into the plug receptacle.

A further development of the invention which increases security against manipulation and unintentional release of the locking means can provide locking means for locking the locking means in the closed position of the safety device.

In an expedient development of the invention, an implementation of the locking means which is cost-effective and can be carried out with the aid of simple mechanical means is provided in that the locking means comprise screw means.

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In a preferred embodiment of the invention, easy handling of the locking means is ensured in that the locking means comprise mechanical latching means.

In order to enable the plug of the power supply line of the exhaust air system to be intentionally removed from the safety plug device, a further development of the invention can provide release means coupled in an operative relationship with the latching means for releasing the latching means.

In order to increase the safety standard, in an expedient embodiment of the invention it can be provided that the switching device is coupled to detection means, whereby with the aid of the detection means it can be determined whether the safety device is in the closed position, so that the electrical connection between the plug device and the plug receptacle can only be closed when the safety device is in the closed position.

The invention is explained in more detail below using exemplary embodiments with reference to a drawing.

Figure 1 is a schematic block diagram to explain a safety circuit

arrangement for exhaust air systems;

Figure 2 shows a safety plug device with a bracket;

Figure 3 is a schematic drawing of a safety plug device with snap-in

means;

Figure 4 is a schematic perspective view of a safety plug device

with a bracket as a locking device;

Figure 5 is another schematic perspective view of the safety

Plug-in device according to Figure 4;

Figure 6 is a schematic representation of another embodiment of a safety

safety connector with a locking strap;

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Figure 7 is a schematic perspective view of a safety plug device

with a locking pin as a locking device;

Figure 8 is a side view of the embodiment of Figure 7; and

Figure 9 shows another embodiment of a safety plug device with safety

locking bolt as a locking device.

Figure 1 shows a schematic representation to explain a safety circuit arrangement for an electrically operated exhaust air system, for example an extractor hood, an exhaust air dryer, a gas boiler or the like. A control element 1 comprises a contact device 2 and a transmitter device 3. The contact device 2 is coupled to an air supply system 4 with which air can be supplied to a room.

The contact device 2 can, for example, be a reed contact or a mechanical button. The contact device 2 can have at least two switching states. The contact device 2 is in a first switching state when the supply air system 4 is open. The supply air system 4 is, for example, a window or a supply air flap. The transmitter device 3 recognizes from the switching state of the contact device 2 whether the supply air system 4 is open or closed. If the supply air system 4 is open, the transmitter device 3 generates a first control signal and transmits this to a receiver device 5 arranged spatially separate from the transmitter device 3. A second control signal is transmitted from the transmitter device 3 to the receiver device 5 if the transmitter device 3 recognizes from the switching state of the contact device 2 that the supply air system 4 is closed.

Depending on whether the receiver device 5 receives the first or second control signal, the closing or opening of a switching device 6 is initiated. The switching device 6 is coupled to a power supply line 7 of an exhaust air system (not shown). By closing or opening the power supply line 7 with the aid of the switching device 6, electrical operation of the exhaust air system is enabled or prevented.

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To transmit the first and second control signals, a communication connection 8 is formed between the transmitter device 3 and the receiver device 5. This can be a cable connection or a radio connection. In the case of a cable connection, the control signals can be transmitted directly from the contact device 2 to the switching device 6 without the interposition of the transmitter and receiver devices 3, 5. If the first and second control signals are transmitted using radio signals, the transmitter device 3 is a radio transmitter and the receiver device 5 is a radio receiver.

The control element 1 is connected to a power supply 9. The power supply 9 is preferably a battery that can be conveniently recharged using solar energy. The receiver device 5 is connected to a power source 10. This can preferably be a connection to a landline network.

Figure 2 shows a side view of a safety plug arrangement 40 that can be used in conjunction with an implementation of the safety circuit arrangement according to Figure 1. A plug device 42 with plug contacts 43, 44 is formed on a rear side 41 of the safety plug device 40. The plug device 42 serves to insert the safety plug device 40 into a standard socket, for example a 220/230 V socket of a household power supply. On a front side 45, the safety plug device 40 has a plug receptacle 46 with connection sockets 47, 48. The plug contacts 43, 44 and the connection sockets 47, 48 are arranged one above the other in Figure 2 for better illustration; however, they could also be arranged one behind the other. However, the exact position of the plug contacts 43, 44 and the connection sockets 47, 48 relative to one another is not important for the invention.

A plug 49 is inserted into the plug receptacle 46. The plug 49 is in a fully inserted position in the plug receptacle 46. The connection sockets 47, 48 are connected via a switching device 50 to the plug contacts 43, 44 of the plug device

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42. With the help of the switching device 50, the electrical connections between the plug contacts 43, 44 and the connection sockets 47, 48 can be closed or interrupted with a switch included in the switching device 50. In this way, an electrical voltage which is tapped with the help of the plug contacts 43, 44 when the plug device 42 is inserted into a socket is made available via the connection sockets 47, 48, provided the switching device 50 closes the electrical connections between the plug contacts 43, 44 and the connection sockets 47, 48. With the help of the plug 49, the electrical voltage can then be tapped in such a way that it is fed to an exhaust system (not shown) via a voltage supply line 51.

The switching device 50 switches the electrical connections between the plug contacts 43, 44 and the connection sockets 47, 48 depending on a control signal which is received by a receiver device 52, which is also arranged in a housing 53 of the safety plug device 40. The receiver device 52 receives the control signals from a transmitter device (not shown in Figure 2), which is connected to a contact device of a supply air system, as was explained in connection with Figure 1. The receiver device 52 can exchange electronic data signals with the transmitter device via a cable connection or a radio connection.

According to Figure 2, a safety device is provided on the safety plug device 40 which can be moved between a closed position (solid lines in Figure 2), in which the plug 49 is covered by a bracket 60, and an open position (dashed lines in Figure 2). In the embodiment shown in Figure 2, the bracket 60 is pivotally mounted on the housing 53 of the safety plug device 40 on an axis 61 which is fastened to the housing 53. In this embodiment, the bracket 60 can be pivoted in order to remove the plug 49 from the plug receptacle 46 or to insert the plug 49 into the plug receptacle 46. In the closed position, a deformable region 63 of the bracket 60 touches the plug.

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The bracket 60 of the safety device is locked in the closed position by means of locking means (not shown) provided in the housing 53 so that the plug 49 cannot be removed from the plug receptacle 46. The housing 53 provides an engagement opening 62 in order to be able to release the locking means when the bracket 60 is to be moved from the closed position to the open position.

In the closed position of the safety device, one end 57 of the bracket 60 acts on a switch 58, so that with the help of the switch 58 it can be detected whether the safety device is in the closed position. The switch 58 sends a signal to the switching device 50 that depends on the position of the safety device.

The switching device 50 is designed in such a way that the electrical connection between the contact connections 43, 44 and the connection sockets 47, 48 can only be closed if it is determined with the aid of the switch 58 that the bracket 60 is in the closed position. The automatic detection of the locking state of the safety device achieved in this way is an additional measure to ensure that a voltage supply via the plug 49 and the voltage supply line 51 can only take place when the bracket is closed. The provision of the bracket 60 alone, however, already means that the plug 49 can be secured against unwanted removal from the plug socket 46. This measure in itself improves the safety standard when operating exhaust air systems with the aid of a safety circuit arrangement as described in connection with Figure 1.

Locking the safety device in the closed position can alternatively or additionally be carried out using suitable means. For example, an advantageous embodiment can provide that the bracket 60 is screwed to the housing 53 using a screw. A special screw can be used as the screw, which can only be rotated in one direction or with the help of a special key.

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Figure 3 shows a schematic drawing of the safety plug device 40, in which a possible embodiment of locking means is shown. The locking means comprise a spring 64, at the end of which there is a locking pin 65. The locking pin 65 engages in a recess 66 which is formed in the bracket 60. In Figure 3, the safety device is shown in its closed position, in which the locking pin 65 is locked in the recess 66 and is held in the locked position by the spring 64. By exerting a force in the direction of an arrow 67 on the spring 64, the locking pin 65 can be moved out of the recess 66 so that the bracket can be pivoted from the closed position into the open position. The force can be exerted with the aid of a tool through an engagement opening (not shown) in the housing 53. Alternatively, release means, for example a pin (not shown), could be provided on the spring 64 in order to be able to release the locking means.

Figure 4 shows a further embodiment of the safety plug device 40 in an open position. In order to move the safety device into the closed position so that the bracket 60 is pivoted over the plug receptacle 46, the bracket can be pivoted in the direction of an arrow 68. In one side 69 of the housing 53, the engagement opening 62 is provided, which allows access to locking means (not shown) within the housing 53.

Figure 5 shows a side view of the safety plug device 40 according to Figure 4 with an inserted plug 49. The bracket 60 is moved from the open position (dashed representation) to the closed position (solid representation) as indicated by arrows 70.

Figure 6 shows a side view of another embodiment of the safety plug device 40. A locking band 71 is attached to opposite sides of the plug receptacle (not shown) by means of screws 72. The screw 72 can be a special screw that can only be screwed in or loosened with a special tool. The locking band 71 can, in a preferred embodiment,

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guide shape should be elastic so that it adapts well to different plug shapes and sizes. Preferably, the locking band 71 is releasably attached to at least one of the opposite sides of the plug receptacle.

Figure 7 shows a plan view of an embodiment of a safety plug device 40. On opposite sides 72, 73 there are guides 74, 75, the holes 76,

77. Advantageously, one of the holes 76, 77 has a thread. In the closed position, a locking pin 78 is attached to the holes, which touches the plug 49 inserted into the plug receptacle 46 and thus firmly locks it. The locking pin

78 preferably has an external thread at one end that matches the thread of the holes 76, 77, with which the locking pin 78 is screwed into one of the holes 76, 77 in the closed position of the safety device. The locking pin 78 can be deformable in a central pin section 79 or can comprise deformable means that are deformed in the closed position of the safety device and thus exert a restoring force on the plug 49.

Figure 8 shows a side view of a safety plug device 40 according to Figure 7.

Figure 9 shows an embodiment of a safety plug device 40. In the plug receptacle 46, which is designed as a Schuko plug receptacle, there are two guide grooves 80, 81. A Schuko plug 49 is plugged into the plug receptacle 46 and is connected to a power supply line 51. Guide projections 82, 83 of the Schuko plug 49 engage in the guide grooves 80, 81. Safety bolts 84, 85 engage laterally in the guide grooves 80, 81. In doing so, they touch the guide projections 82, 83 of the Schuko plug 49 and lock the Schuko plug 49 firmly in the plug receptacle 46. In the open position of the safety device, the safety bolts 84, 85 are laterally retracted from the guide grooves 80, 81 (dotted representation). In the closed position of the safety device, the locking bolts 84, 85 can squeeze the guide projections 82, 83 of the plug 49 of the power supply line 51 or the guide grooves 80, 81 at ends which are adjacent to a front side 45 of the safety plug device 40.

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as shown in Figure 9. In this position, the locking bolts 84, 85 engage behind the guide projections 82, 83.

The features of the invention disclosed in the above description, the claims and the drawings can be important both individually and in any combination for the realization of the invention in its various embodiments.

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Claims (11)

1. Safety plug device ( 40 ) for an exhaust air system for removing air from a room, with a housing ( 53 ) on which a plug device ( 42 ) for plugging into a socket of a power supply system and a plug receptacle ( 46 ) for receiving a plug ( 49 ) of a power supply line ( 51 ) of the exhaust air system are formed, and a switching device ( 50 ) arranged in the housing ( 53 ) for interrupting/closing an electrical connection between the plug device ( 42 ) and the plug receptacle ( 46 ), wherein the switching device ( 50 ) is connected to a receiver ( 52 ) for receiving control signals from a control element coupled to a supply air system and comprises a switch for interrupting/closing the electrical connection between the plug device ( 42 ) and the plug receptacle ( 46 ) depending on the control signals received from the control element, wherein on the housing (53) a switch (50) is arranged. 53 ) a safety device is provided which can be moved between an open position, in which the plug ( 49 ) of the power supply line ( 51 ) of the exhaust air system can be inserted into/removed from the plug receptacle ( 46 ), and a closed position, in which removal of the plug ( 49 ) of the power supply line ( 51 ) from the plug receptacle ( 46 ) is prevented, characterized in that the safety device comprises locking means ( 60 ; 71 ; 79 ; 84 , 85 ) which, in the closed position of the safety device, lock the plug ( 49 ) of the power supply line ( 51 ) in the plug receptacle ( 46 ) in an inserted position. 2. Safety plug device according to claim 1, characterized in that the safety device comprises a pivotably mounted bracket ( 60 ) as a locking means which, in the closed position of the safety device, touches the plug ( 49 ) of the power supply line ( 51 ) inserted into the plug receptacle ( 46 ) from a side facing away from the plug receptacle. 3. Safety plug device according to claim 1, characterized in that the safety device comprises a locking band ( 71 ) spanning the plug ( 49) of the power supply line (51 ) as a locking means, which in the closed position of the safety device touches the plug ( 49 ) of the power supply line (S 1) inserted into the plug receptacle (46) from the side facing away from the plug receptacle ( 46 ), wherein at least one side of the locking band ( 71 ) is detachably fastened. 4. Safety plug device according to claim 1, characterized in that the safety device comprises guides ( 74 , 75 ) with bores ( 76 , 77 ) and a locking pin ( 79 ) which can be displaced essentially perpendicularly to an insertion direction of the plug ( 49 ) of the power supply line ( 51 ) into the plug receptacle ( 46 ) as a locking means, which is held in the bores ( 76 , 77 ) in the closed position of the safety device and touches the plug ( 49 ) of the power supply line ( 51 ) inserted into the plug receptacle ( 46 ) from the side facing away from the plug receptacle ( 46 ). 5. Safety plug device according to claim 1, characterized in that the plug receptacle ( 46 ) is designed as a Schuko plug receptacle with two opposing guide grooves ( 80 , 81 ) for receiving guide projections ( 82 , 83 ) of the plug ( 49 ) of the power supply line ( 51 ) designed as a Schuko plug, and the locking means comprise two locking bolts ( 84 , 85 ) which engage laterally in the plug receptacle ( 46 ) and which, in the closed position of the safety device, each engage behind the guide projections ( 82 , 83 ). 6. Safety plug device according to one of the preceding claims, characterized in that the locking means ( 60 ; 71 ; 79 ; 84 , 85 ) comprise a deformable region which is deformed in the closed position and exerts a restoring force on the plug ( 49 ) of the power supply line ( 51 ) acting essentially in the direction of insertion of the plug (49) of the power supply line ( 51 ) into the plug receptacle ( 46 ). 7. Safety plug device according to one of the preceding claims, characterized by locking means ( 56 ) for locking the locking means ( 60 ; 71 ; 79 ; 84 , 85 ) in the closed position of the safety device. 8. Safety plug device according to claim 7, characterized in that the locking means ( 56 ) comprise screw means. 9. Safety plug device according to claim 7 or 8, characterized in that the locking means ( 56 ) comprise mechanical latching means ( 65 ). 10. Safety plug device according to claim 9, characterized by release means coupled in an operative relationship with the latching means ( 65 ) for releasing the latching means ( 65 ). 11. Safety plug device according to one of the preceding claims, characterized in that the switching device ( 50 ) is coupled to detection means ( 58 ), it being possible with the aid of the detection means ( 58 ) to determine whether the safety device is in the closed position, so that the electrical connection between the plug device ( 42 ) and the plug receptacle ( 46 ) can only be closed when the safety device is in the closed position.