An industrial electrical socket unit and an interlocking switch

Abstract

 An electrical socket unit (1) for industrial equipment comprises a socket (6) connected electrically to an automatic switch (5) of the type which has to be enabled in order to be switched on, and has a preventing/enabling slider (28) which is moved, by means (7) for detecting that a plug (9) has been inserted in the socket (6), from and into a position in which the switch (5) is prevented from being switched on.

Description

[0001] The present invention relates to an electrical socket unit for industrial equipment, comprising a switch and a socket connected to one another electrically, and means for detecting that a plug has been inserted in the socket in order to prevent the switch from being switched on when the plug has been removed from the socket.

[0002] Socket units which include features of this type are used in industrial installations to protect the operators against electrical discharges when inserting a plug in the socket or removing it therefrom.

[0003] For this purpose, the sockets are constructed in such a manner that the switch can be switched on only if the plug is inserted in the socket. Systems such as mechanical locking devices or latches are also provided and act on the plug to prevent it from being removed from the socket if the switch is switched on.

[0004] A disadvantage of such sockets is that the associated switch is of the rotary, unprotected type, and does not switch off automatically, since the plug has to be removed manually from the socket.

[0005] The technical problem on which the invention is based is to produce a socket unit which ensures that the switch is switched off automatically when the operator removes the plug from the socket by mistake, without having first of all switched off the switch, in order to protect the operator and safeguard the operation of the socket.

[0006] This problem is overcome by means of an electrical socket unit of the type mentioned at the beginning, characterised in that the switch is an automatic switch of the type which has to be enabled in order to be switched on, and has a preventing/enabling slider which can move from and into a preventing position in which the switch is switched off and kept switched off, and is prevented from being switched on, the means for detecting that the plug has been inserted being connected kinematically to the slider so as to move it into its preventing position when the plug is removed from the socket.

[0007] To advantage, a mechanism for switching on the switch may be associated with a latch which can restrain the plug in the socket when the switch is switched on.

[0008] The invention will now be described in greater detail with reference to a preferred embodiment, illustrated by way of non-limiting example in the appended drawings, in which:

• Figure 1 is a perspective view of an electrical socket unit for industrial equipment according to the invention, with the plug not inserted in the socket,
• Figure 2 is a perspective view of the socket of Figure 1, with the plug inserted in the socket and the switch switched on,
• Figure 3 shows a detail of the preceding figures,
• Figure 4 shows a further detail of the first two figures, and
• Figure 5 shows a third detail of the first two figures.

[0009] In Figures 1 and 2, an electrical safety socket unit for industrial equipment according to the invention is indicated 1. The socket unit includes a box 2 composed of two interconnectable shells 3, 4. An automatic switch 5 of modular structure, a socket 6, detection means 7, and a latch 8 are mounted on the shell 4. The socket 6 and the plug 9 are a typical socket and plug for supplying electrical equipment. The automatic switch 5 has a modular structure comprising two or more (commonly three) modules 26 fitted side by side. Each module 26 has a bistable switching lever 27 and a preventing/enabling slider 28 accessible via a slot 29. The bistable levers 27 are connected rigidly to one another by means of a crosspiece 30, and are movable between rest positions in which the socket 6 is not supplied with electricity since the switch 5 is switched off, and operating positions in which the socket 6 is supplied since the switch 5 is switched on. The slider 28 has a preventing position, in which, although the bistable lever 27 can be moved between its rest and operating positions, the switch 5 cannot be switched on and an enabling position in which the bistable lever 27 can switch on the switch 5. The detection means 7 comprise a feeler 10 and a triangular frame 11 pivotable inside a casing 12. The feeler 10 includes a rod-shaped piston 13 movable axially in a seating 14, and a projecting lever 15 with a slot 16. The seating 14 comprises a cylindrical tube 17 inside which the piston 13 and a stirrup 18, which is engaged in an axial slot 19 in the piston 13, are slidable.

[0010] Inside the piston 13 is a spring 20 which is compressed between the stirrup 18 and an abutment surface 21 within the piston 13 in such a manner that, when the plug 9 has not been inserted, the feeler 10 is biased towards the socket 6 into a rest position (shown in Figure 1, and in broken outline in Figure 3). When the plug 9 has been inserted in the socket 6, it pushes the feeler 10 away from the socket 6 by means of an appendage 9a, and moves it into its operating position (shown in Figure 2, and in continuous outline in Figure 3). Two opposed appendages 22a, 22b disposed at the end 23 of the piston 13 are engaged in contact with the slot 16 in the projecting lever 15 and can pivot the lever 15 towards the socket 6 so as to raise the lever. The triangular frame 11 is fixed pivotably to the casing 12 at a vertex 31, its other two vertices having respective first and second pins 32, 33 which project from opposite sides of the casing 12 through respective slots 34, 35. The first pin 32 engages the preventing/enabling slider 28, whereas the second pin 33 engages and bears against the projecting lever 15. The triangular frame 11 can be moved between a rest position (shown in broken outline in Figure 5), in which the pin 32 keeps the preventing/enabling slider 28 in its preventing position, and an operating position (shown in continuous outline in Figure 5), in which the pin 32 keeps the slider 28 in its enabling position. A spring 36 coiled at the vertex 31 acts between an abutment 37 integral with the casing 12 and a side 38 of the triangular frame 11, so as to urge the frame 11 into its rest position. Since the projecting lever 15 bears against the pin 33, it opposes the action of the spring 36 and, when the plug 9 is inserted in the socket, can move the frame 11 into its operating position and accordingly move the slider 28 into its enabling position. The latch 8 is pivotable about an axis X-X and is movable between a rest position 8' (shown in broken outline in Figure 4), in which the plug 9 can be inserted in and removed from the socket 6, and an operating position (shown in continuous outline in Figure 4) in which the plug 9 is restrained in the socket 6. The latch 8 has a first arm 24 having a projection 47 in the form of a tooth, and a second arm 25 having a seating 46 in the form of a half-housing. The projection 47 of the first arm 24 can engage the appendage 9a of the plug 9 so as to prevent the plug 9 from being removed when it has been inserted in the socket 6. The seating 46 of the second arm 25 is engaged in contact with a first end 44a of a rod 41 housed in the casing 12. The first end 44a is bent at right-angles and projects from the casing 12 through a slot 45 (Figure 5). A second end 44b of the rod 41 is articulated on an appendage 43 of a lever 42. The lever 42 is firmly fixed to the bistable levers 27 by means of the crosspiece 30, and can move between a rest position, indicated in broken outline in Figure 5, and an operating position indicated in continuous outline in Figure 5. The latch 8 is kept in its rest position by the action of a biasing spring 40 connected to the latch 8 and anchored to the shell 4. The latch 8 is urged into its operating position by the end 44a of the rod 41, when the lever 42, and hence the bistable levers 27, are in their operating positions.

[0011] When the plug 9 has been removed from the socket 6, the piston 13 is in its rest position, and the projecting lever 15 and the triangular frame 11 are correspondingly in their rest positions. The pin 32 of the frame 11 keeps the slider 28 in its preventing position so that the automatic switch 5 is prevented from being switched on and power is not supplied to the socket 6. The bistable levers 27 and the lever 42 are in the rest position and the spring 40 keeps the latch 8 in a position such that the plug can be inserted.

[0012] When the plug 9 is inserted in the socket 6, it moves the piston 13, and consequently the projecting lever 15 and the frame 11, into the operating position. In these conditions the pin 32 keeps the slider 28 in its enabling position and the automatic switch 5 can be switched on by means of the levers 27. As the levers 27, and consequently the lever 42 which is fixed to the levers 27, pivot to their switching-on positions the rod 41 moves into its enabling position and pulls the latch 8 into its operating position, locking the plug 9 in the socket 6.

[0013] The plug 9 can be removed only if the levers 27 and 42 are moved into their rest positions, so as to switch off the switch 5, interrupt the supply to the socket 6, and move the latch 8 into its rest position. If the plug 9 is somehow removed from the socket 6 when power is supplied to the socket 6, the switch 5 is switched off automatically, thus ensuring that the operator is protected. When the plug 9 is removed, the piston 13 moves into its rest position, and the projecting lever 15 and the triangular frame 11 consequently also move into their rest positions. The first pin 32 of the frame 11 keeps the slider 28 in the position in which it prevents the switch from being switched on, so that the switch 5 is switched off automatically and the supply to the socket 6 is cut off.

[0014] Should the latch 8 fail because it is either broken or detached, the plug and switch unit according to the invention remains safe, since the associated switch is switched off when the plug is removed from the socket and, in any case, does not allow the switch to be closed when the plug is not in the socket.

[0015] The operator is thus always protected.

Claims

1. An electrical socket unit (1) for industrial equipment comprising a switch (5) and a socket (6) connected to one another electrically, and means (7) for detecting that a plug (9) has been inserted in the socket (6) in order to prevent the switch (5) from being switched on when the plug (9) has been removed from the socket (6), characterised in that the switch (5) is an automatic switch of the type which has to be enabled in order to be switched on and has a preventing/enabling slider (28) which can move from and into a preventing position in which the switch (5) is switched off and kept switched off, and is prevented from being switched on, the means (7) for detecting that the plug (9) has been inserted being connected kinematically to the slider (28) so as to move it into its preventing position when the plug (9) is removed from the socket (6).

2. An electrical socket unit according to Claim 1, including a latch (8) associated with the switch (5) in order to restrain the plug (9) in the socket (6) when the switch (5) is switched on.

3. An electrical socket unit according to Claim 1, in which the switch is of the type with a modular structure and the detection means (7) include first and second pins (32,33), which project from opposite sides of a casing (12) which is the same shape as the automatic switch (5), and is positioned closely adjacent the switch (5), the first pin (32) engaging the preventing/enabling slider (28) and being integral with the second pin (33), and the second pin (33) being associated with a projecting lever (15) of a feeler (10) and movable between a rest position in which the slider (28) is in a preventing position, and an operating position in which the slider (28) is in a position such that the switch (5) can be switched on, the feeler (10) including a piston (13) which acts on the projecting lever (15) and can move the second pin (33) between its rest position which it occupies when the plug (9) has been removed from the socket (6) and its enabling position which it occupies when the plug (9) is inserted in the socket (6).

Drawing