DE69611005T2 - Lamp holder for switching device attached to a wall and corresponding switching device - Google Patents

Description

The present invention relates to a lamp holder for a wall-mounted switch assembly and the switch assembly related thereto.

It is known that modular electrical switches are available on the market for installation on walls by means of an intermediate plate or a support frame to which a plurality of switch modules or "fruits" can be attached.

These switches are often provided with a housing for a lamp to indicate the open or closed state of the switch, with the lamp positioned below a rocker switch or button (which is transparent or has a transparent window) that operates the switch.

Typically, the indicator light, which is preferably a neon lamp, enables the position of the switch to be seen even in the dark and is consequently energized and therefore turned on when the switch is open and off when the switch is closed.

In some cases, however, it may be necessary to make the closed state of the switch visible by switching on the lamp accordingly.

This is particularly the case for switches that control remote light sources, such as external lights, that are operated from inside, or for electrical devices other than light sources, such as fans, heaters, air conditioners and the like.

Currently, lamps or lighting systems are used that include load stabilizing resistors connected to cables connecting them to terminals of the switch assembly or to at least power supplies controlled by the switch to provide such position and indication functions.

It is not very easy to use these lamps because their power cables have a small cross-section and are difficult to insert into the connectors provided for the power cables or, once inserted, they easily slip out and are not clamped and not very reliably held, to the detriment of the functionality and safety of the system.

Although on the one hand such lamps are versatile, since their supply cables can be connected in different ways according to the very different requirements of different systems, they have the further disadvantage that the installer must necessarily examine the electrical system and the switching device in order to make the most suitable connections.

The term switch actually refers to an electrical device of essentially two types:

- simple single-pole switches with open contact (known by the acronym SPST (= Single Pole - Single Throw))

- single-pole two-way contact switches or single-pole double throw switches, which are known by the acronym SPDT (= Single Pole - double Throw).

It is clear that the connection of a position lamp to the electrical device or system must be carried out in different ways according to the type of electrical device and the desired function.

In the case of a position lamp associated with a single switch and which lights up when the switch is open, it is clear that the lamp must be connected in parallel with the switch, i.e. the two electrical terminals of the switch.

In the case of a position lamp associated with a switch which lights when the switch is closed to supply an electrical load, the lamp must be connected in parallel with the load, i.e. its terminals must be connected respectively to a terminal of the switch from which the load receives its supply and to the return wire to the mains supply.

For this application, which is not very common, modular switches can be provided with an auxiliary terminal, electrically isolated from the switch contacts, which allows a mains return wire to be mechanically attached to a lamp terminal and electrically connected.

In the case of a two-way switch or changeover switch, the position lamp must be connected between the two terminals corresponding to the switched terminals.

These different requirements have prevented manufacturers to date from developing a modular device or lamp holder that can be safely, reliably and only in one way to a number of different electrical devices.

DE-A-17 90 269 discloses a lamp holder and an electrical switch arrangement according to the preamble of claim 1 and claim 4, respectively.

The present invention solves this problem by providing a lamp holder for electrical switch assemblies, which can be electrically connected in a suitable manner to electrical switch assemblies having different functions by a simple mechanical coupling, without the possibility of error, and in a very reliable manner.

The present invention further provides a family of functionally different electrical equipment that can be coupled to the lamp holder and that consists of a plurality of common structural elements, the different functions resulting from very small modifications during construction that do not affect the mass production of the individual components and combinations thereof.

These results are achieved by providing a lamp holder in which a generally rectangular box-shaped insulating block serves as a lamp support and as a housing for connecting wires for electrically connecting the lamp to a plurality of electrical pressure contacts, preferably three, projecting from a pair of opposite sides of the block which, when the block is tightly fitted between two insulating pins formed by the insulating body of a switch assembly, contact electrical terminals housed in the insulating pins of the body of the assembly by passing through corresponding slots formed in the insulating pins and extending in the direction of the fit of the block.

Other characteristics are the same, with the selective presence or absence of one of the three slots in the pins of the electrical assembly determining its function as a one- or two-way switch.

The provision of an electrically isolated terminal in one of the pins also enables the switch to be connected to a Indication of the closed state of the contacts of the same.

The characteristics and advantages of the invention will become more apparent from the following description and from the accompanying drawings in which;

Figure 1 is an exploded perspective view of a switch module known in the art that can be readily modified to convert it into a single switch or a two-way switch in accordance with the present invention;

Fig. 2 is an electrical circuit diagram showing the connection of a position lamp to a switch;

Fig. 3 is an electrical circuit diagram showing the connection of a position lamp to a two-way switch;

Fig. 4 is an electrical circuit diagram showing an indicator lamp for indicating the closed state of a switch;

Fig. 5 is an exploded perspective view of a preferred embodiment of a lamp holder block for coupling to a switch module according to the present invention and a sub-element of a switch module modified according to the present invention;

Fig. 6 is a perspective view of a sub-element of a switch module acting as a simple switch and modified according to the present invention for coupling to a lamp holder for a position lamp;

Fig. 7 is a perspective view of a subelement of a switch module acting as a two-way switch and modified according to the present invention for coupling to a lamp holder for a position lamp; and

Fig. 8 is a perspective view of a subelement of a switch module acting as a simple switch and modified according to the present invention for coupling to a lamp holder for an indicator lamp for indicating the closed state of the switch.

For a better understanding of the invention, a switch assembly of the modular type known in the art is shown in Fig. 1.

The assembly comprises a box-shaped insulating housing formed by two shells 1, 2 molded from a plastic material and joined together by gluing or heat sealing.

The shell 1 forms a prismatic frame having internal ribs 3 and eyes 4. The eyes 4 carry a front rocker switch 5 operable by the user and provided with a hollow rod 6 which houses and guides a switch pin 7 which is urged by a compression spring 8 to act on a rocker arm 9 of conductive material.

The inner ribs 3 form a suitable seat for a transparent plastic block 10 with a high refractive index, which serves as a reflector for a light source housed in a cavity 11 in the reflector.

The inner ribs 3 also form a suitable guide housing for the rocker arm 9.

With reference to the condition of use and installation of the switch assembly, the shell 2 closes the rear end of the frame 1 and consists essentially of a flat member with a pair of hollow box-shaped members 12, 13 protruding from the rear surface of the shell 2.

The box element 12 is formed of two prismatic housings, which are separated and insulated from each other by an insulating partition which is not visible, for receiving the first and second electrical terminal connections 14, 15 respectively.

A third connection 16 can be housed in the box element 13.

The structure of each terminal 14, 15, 16 is conventional and, with reference to terminal 16, comprises a fixed metal clamping member 17 formed by bending a flat element into a C-shape or into a rectangular annulus, and a nut element 18 with a threaded seat housed between the arms 18A, 19 of the fixed clamping member. A hole 20 is formed in the fixed clamping member for the passage of a screw 21 which engages the nut element 18 and acts as a movable clamping member.

The ends of the electrical wires can be inserted through openings 22, 23 in an end wall of the box element 13 and between the clamping members to be clamped by the same.

The clamping screw 21 of the connector 16 is rotatable through an opening 24 formed in a surface of the box element 13.

The structure of the terminals 14, 15 is completely similar and the clamping screws 25, 26 thereof are through openings (not visible in Fig. 1) while the openings 27, 28 are provided for the introduction of the wires. The structure of the terminals 15, 16, 17 is completed by a conductive wing member which differs according to the function to be achieved.

In the case of terminals 15 and 16, each having the same function of forming a fixed contact of the switch, each fixed clamping member comprises an extended wing member 29, 30, respectively, carrying a contact boss to be contacted by a corresponding boss 31, 32 at one of the two ends of the rocker arm 9.

In the case of the terminal 14 serving as a sliding contact and as a support for the rocker arm 9, the fixed clamp member comprises an extended wing member 33 terminating in a cross-beam blade 34 for sliding contact with the central portion of the rocker arm 9.

Depending on the position of the switching rocker switch 5, the rocker arm 9 slides on the terminal 34 and rotates on the same to form an electrical connection between the terminal member 14 and the terminal member 15 or between the terminal member 14 and the terminal member 16 in a mutually exclusive manner.

An opening 35 in the shell 2 allows a light source to be introduced into the cavity in the reflector 10.

Conventional hook teeth formed on two opposite surfaces of the shell 1, one 36 of which is visible in Fig. 1, enable the switch assembly to be snap-fitted into a wall support plate, possibly with several pieces of electrical equipment side by side.

It is therefore clear that the described switch arrangement can fulfil either the function of a two-way switch or a simple switch and can be equipped with a switch position lamp.

If the function of the assembly is that of a simple switch, then terminal 16 is in practice superfluous and, for reasons of economy, does not fit into the housing of the assembly which is sold as a different product from the two-way switch.

In both cases, this modular structure in combination with a position light source has the previously mentioned disadvantages of difficult connection, low reliability and safety and the risk of errors made in the connections.

It is indeed clear with reference to Figs. 2, 3, 4 that the electrical connections which must be formed between the light source and the switch arrangement differ according to the circumstances.

In the case of a simple switch (Fig. 2) with a position lamp, terminal 14 is connected to a main supply wire (generally the live wire), and terminal 15 is connected to a terminal of the load L, the second terminal of which is connected to a second main supply wire (generally the neutral or dead wire),

The position lamp must be connected between terminal 14 and terminal 15.

Terminal 16 is superfluous and, if present, can cause further wiring errors.

In the case of a two-way switch with a position lamp (Fig. 3), terminal 14 is connected to a main supply wire and terminals 15 and 16 are connected to two switching lines connected to a load L through a second two-way switch.

The position lamp must be connected between terminals 15 and 16.

Finally, in the case of a switch with a closed state indicator lamp (Fig. 4), the switch terminals 14 and 15 must be connected to the main supply and the load as in Fig. 2, but the lamp must be connected in parallel with the load L, therefore with one fixed terminal to the terminal 15 and with the other fixed terminal thereof to an anchoring terminal 37 which is not formed as, and does not form part of, the switch assembly considered in Fig. 1.

Fig. 5 shows several simple structural modifications to the switch assembly of Fig. 1 which enable it to be operated together with a lamp holder further shown in Fig. 5, whereby the different connections required for each type of operation are automatically formed in a reliable manner without difficulty or risk of error and with minor complications of manufacture.

Since the only element of the switch assembly which is modified is the shell 2, only this is shown. The two box elements 12, 13 of the shell 2, due to their box shape, form two tenons between which an insulating block 40 of rectangular box shape can be closely fitted, the block having a generally L-shaped cross-section in a plane parallel to the closure plate of the shell 2.

The two elements 12, 13 are referred to as tenons in the following.

The insulating block 40, which is hollow and has ribs, only partially shown, forms a housing for a plurality of electrical conductors or connecting wires positioned within the block by the internal ribs.

The block is closed by a cover 41 preferably on the face of the block 40 which, when the block is engaged between the pins 12, 13, lies against the closure plate of the shell 2.

The cover 41 may be secured to the block 40 by heat sealing or by screws or by resiliently snap-engageable teeth. The cover 41 carries a cylindrical collar 42 which partially houses and positions a small neon bulb 43, the connecting wires 44, 45 of which project into the block 40.

The two opposite parallel walls 46, 47 of the block 40, which contact the mutually directed parallel walls 48, 49 of the pins 12, 13, have openings for the passage of the three electrical pressure contacts 50, 51, 52, conveniently, but not necessarily, formed by the ends of the connecting wires anchored inside the block to form resilient, projecting supports for the contacts 50, 51, 52.

The contacts 50 and 51 are conventionally arranged in the wall 47 so that the fit of the block between the pins 12, 13 causes the contacts 50, 51 to be inserted into corresponding slots 53, 54 which are elongated in the direction of the fit of the block and through which the Contacts 50 and 51 contact the fixed terminal members of terminals 15 and 14, respectively.

Similarly, the contact 52 is positioned in the wall 46 so that the fit of the block between the pins 12, 13 causes the contact 52 to be inserted into a slot 55 so that it comes into contact with the fixed clamping member of a terminal housed in the pin 13.

The contact 51 is connected by a connecting wire to a contact terminal 57 which engages a lamp terminal 44 and by a connecting wire 58 to the contact 52.

The contact 50 is connected by a connecting wire 59 to one terminal of a load limiting and stabilizing resistor 60, the other terminal of which is connected by a connecting wire 61 to a contact terminal 62 which engages the terminal 45 of the lamp 43.

It is clear that instead of the neon bulb, which is preferred due to the low power it uses, a photo-emitting diode or other light source can be used.

If an incandescent lamp is used, the load limiting resistor 60 may be superfluous.

The lamp holder described is a universal, optional module that can be adapted to any switch arrangement, whatever its specific function as a one-way or two-way switch or as a switch with a status indicator.

The switch arrangement can be adapted to the different requirements with extremely small changes during production as shown in Figs. 6, 7, 8 which show a shell 2 of a switch assembly specifically manufactured to act as a simple switch, a two-way switch and a switch with a closed state indication, respectively.

Since in a simple switch each position lamp must be connected between the terminals 14 and 15 (Fig. 2), in Fig. 6 the pin 12 with two slots 53, 54 is provided between the terminals 14, 15 for switching the series circuit formed by the contact 50, the connecting wire 59, the resistor 60, the connecting wire 61, the terminal 62, the lamp 43, the terminal 57, the connecting wire 56 and the rod 51 (Fig. 5).

The slot 55 is superfluous and, for reasons of economy and to avoid errors in connection, the pin 13 preferably has no connection.

In Fig. 7, the shell 2 differs from that of Fig. 6 in that it is specifically intended for a two-way electrical switch assembly and does not have to have the slot 54 but necessarily the slots 53, 55.

This serves to enable the switching of the light source between the terminals 15 and 16 housed in the pins 12 and 13 respectively (Fig. 5) and to prevent the direct permanent connection otherwise formed between the terminal 14 and the terminal 15 by the contacts 51, 52 and the connecting wire 58 of the lamp holder.

Finally (Fig. 8), in the case of the switch with an indication of the closed state, the shell 2 is identical to that of Fig. 7, but the pin 13 must house an auxiliary terminal corresponding to the terminal 37 of Fig. 4 which is electrically isolated from the switching device.

In order to ensure the electrical insulation of the terminal from the other conductive parts of the switch arrangement, it is expedient to provide an insulating section 63 which separates the terminal housing in the pin 13 from the housings in the shell 1 (Fig. 1).

The above description relates exclusively to a preferred embodiment of the invention, and it is clear that many variations can be made thereto without departing from the scope of protection defined in the appended claims.

For example, if commercial reasons suggest that a switch arrangement should be marketed which can operate either as a single switch or as a two-way switch, this can be done with a shell 2 as shown in Fig. 5 with three access slots 53, 54, 55, while it is necessary to manufacture the lamp holder particularly for the two different applications, in one case by removing the contact 52 and in the other case the contact 51, so as to supply two separate products to the market, or, equally possible, the task of removing or isolating one of the contacts can be assigned to the installer.

Alternatively, it is possible to provide the lamp holder with a selector device which separates one or the other of the contacts 51 and 52 from the internal connecting wires.

However, it is clear that these alternative solutions are a more complicated solution to the problems and disadvantages considered, and although they offer greater reliability and simplicity of connection of a position lamp with a switch arrangement, they do not really and completely guarantee the risk of installation errors.

Claims (7)

1. A lamp holder for a wall-mounted electrical switch assembly, having the following features: a rectangular box-shaped insulating block (40-42) which can be closely fitted in a predetermined direction between two insulating pins (12, 13) formed by an enclosure (1, 2) of an electrical switch assembly, two opposite walls (46, 47) of the block (40-42) being in contact with a pair of facing walls (48, 49) of the two pins (12, 13), at least one pair of electrical terminals (14, 15, 16) being housed in the pins (12, 13); - wherein the insulating block (40-42) is formed with a light source carrier (41, 42) and a housing (40) for connecting wires (56, 58, 59, 61) for switching the light source (43) between a first (52) and a second (50) electrical pressure contact, each exposed on the block (40-42) on one of the walls (46, 47) of the block (40-42) which is in contact with one of the facing walls (48, 49) of the pins (12, 13) and protruding therefrom to establish electrical contact with at least the pair of clamping terminals (14, 15, 16) through a plurality of slots (53, 54, 55) formed in the pair of facing walls (48, 49) of the pins (12, 13), the slots (53, 54, 55) extend in the predetermined direction, the first contact (52) on one (46) of the two opposite walls (46, 47) of the block (40-42), and wherein the second contact (50) is exposed on the other (47) of the two opposite walls (46, 47), characterized in that the block has a third pressure contact (51) electrically connected to the first contact (52) and exposed on and protruding from the other (47) of the two opposite walls (46, 47). 2. A lamp holder according to claim 1, wherein the block (40-42) further houses a load limiting resistor (60) for the light source (43). 3. A lamp holder according to claim 2, comprising means for electrically isolating the third contact (51) from the first contact (52). 4. A wall-mounted electrical switch assembly for coupling with a modular lamp holder according to claim 1, comprising: - an insulating switch body (1, 2), on the rear wall (2) of which a housing for a light source (43) and two insulating pins (12, 13) adapted to house at least one pair of electrical terminals (14, 15, 16) are formed, the pins (12, 13) being provided for fitting an insulating block (40-42) of a lamp holder between them in a predetermined direction, the two opposite walls (46, 47) of the block being in contact with a pair of facing walls (48, 49) of the pins (12, 13), and - a plurality of slots (53-55) formed in the pair of walls (48, 49) to provide electrical contact between each terminal of at least the pair of terminals and of at least a first (52) and a second (50) pressure contact of the lamp holder block (40-42), characterized in that one (12) of the pins (12, 13) is adapted to house two (14, 15) clamp terminals and the other pin (13) is adapted to house one (16) clamp terminal. 5. A wall-mounted electrical switch assembly according to claim 4 of the simple single-pole trip switch type, wherein the pair of terminals is housed in the one (IZ) of the two insulating pins (12, 13), and the plurality of slots (53-55) comprises a pair of slots formed in the walls (49) of the pair of facing walls (48, 49) of the insulating pin (12) housing the pair of terminals. 6. A wall-mounted electrical switch assembly according to claim 4 of the two-way switching type, wherein two (14, 15) terminals are housed in one (12) of the two insulating pins (12, 13), a first terminal of the two terminals being connected to one of the two switch paths, and a third terminal terminal (16) is housed in the other (13) of the two insulating pins (12, 13) and being connected to the other of the two switch paths, and wherein - the plurality of slots (53-55) comprises a pair of slots (55, 53) formed respectively in one (48) and the other (49) of the pair of facing walls (48, 49) to enable electrical contact between the first (15) and third (16) terminals and the first (52) and second contacts (50), respectively. 7. A wall-mounted electrical switch assembly according to claim 4 of the simple single pole trip switch type, wherein two clamp terminals (14, 15) are housed in one (12) of the two insulating pins (12, 13), and a third clamp terminal (16) is housed in the other (13) of the two insulating pins (12, 13) and is electrically insulated from the switch contact, and wherein the plurality of slots (53-55) comprise a pair of slots (55, 53) formed respectively in one (48) and the other (49) of the pair of facing walls (48, 49) of the pins (12, 13), whereby coupling of the electrical assembly to a lamp holder enables indication of the closed state of the contact by connection of the pair of clamp terminals to respective a main supply connection and with a first load connection and by connecting the third terminal connection with the other main connection and with a second load connection.