The present invention relates to the field of switch and/or commutator contacts used in driving gears, mainly in household appliances.

The commutator-switch is particular in its construction in that by merely inverting the assembly position of some of the parts, a common terminal can be turned into an outlet terminal and vice versa, in the understanding that a common terminal is one through which the current goes into each commutator-switch.

The upsurge of household appliances for many years is leading to a growing tendency to use multiple blocks or strips to connect electric circuit wires to the corresponding components, instead of the conventional wire-to-wire connections. Such use of multiple strips attempts at rationalizing the manufacture and assembly of one of the most difficult parts to automate, namely the appliance's wiring.

Nevertheless, one of the main problems posed using multiple connectors, both when used with the assistance of a printed circuit, and, in particular, when directly connected to component terminals, lies in the arrangement of such terminals in order to try to exploit the possibilities of both the components and the connectors and the means to manufacture the bundles of wires as far as possible.

Driving gears are known which are provided for such purposes, said gears having several (commutator and/or switch) contacts, which are characterized in that each commutator or switch common or current input terminal can be located at two of the three positions usually existing therefor.

This type of commutator-switch unfortunately affords a different internal layout, depending on the terminal arrangement used, and the number of versions of most of the parts comprising the commutator-switch are even doubled, those numbers of the terminals among them again being doubled over the previous situation taking into consideration of the fact that it is almost inevitable to provide the connection with the assistance of a printed circuit applied on suitable versions thereof.

In any case, the basic commutator and/or switch contact structure used in the said devices comprises a swivel-mounted stiff conductor strap, provided with two or three contact heads, one resting permanently upon the respective common or input terminal contact head, such strap swinging on such head, whereas the other head or heads will contact the respective output terminal or terminals head or heads.

This structure is moreover complemented with a rotating lever that drives the aforesaid conductor strap, in turn controlling the latter's movement.

As regards the locking force of the contact heads with respect to each other, and the necessary strength for displacement of the conductor strap and driving lever towards their idle position, this is provided by an helically wound spring.

The disadvantages and problems posed by this type of switches and/or commutators are as set forth hereinbefore.

The preamble of claim 1 is based on FR-A-1 340 217 which describes a commutator in which the position of the common terminal is changed in order to construct the other kind of commutator, in addition to changing the bracing of the mobile conductor strap and the position of the drive cam, this double bracing whithin the commutator housing requires additional internal space and hence a greater commutator size.

The basic structure of the said commutator switch, as the structure described in Patent FR-A-2 105 130, is defined by a swivel-mounted stiff conductor strap, provided with three contact heads, one of which rests permanently on the common or input terminal contact head, such strap swinging on said head, whereas the remaining head or heads will contact an output terminal head, the means piloting the strap comprising three ridges provided in the commutator housing. This commutator structure is complemented with a similarly swivel-mounted drive lever fitted at its end with a projecting feeler that which cooperates with a rotating cam profile to drive the conductor strap through a subsidiary lever or sheet, in turn controlling its movement by means of at least a spring which ensures that the contacts are tight by exerting its pressure upon the conductor strap.

In the commutator of DE-U-72 01 452 different housings are used for the right common terminal and the left common terminal commutator conformations, since the terminals are arranged crosswise in the housing, the terminals of adjacent housings cannot lie facing one another due to the electric requirement of distance between terminals.

It is the object of the invention to provide a new conception of a commutator or switch for the above mentioned purposes, but with the possibility of the common or input terminal being located at two of the three positions provided in the contact-carrier element or box for such terminals, with the peculiarity that regardless of the arrangement chosen, the same parts will always be used, the only changes being some of their positions, this being an advantage with regard to the manufacturing of the parts and their assembly.

Another essential feature of the commutator-switch is that no different driving levers are required, given that the operating conditions (forces and driving lever and conductor strap stroke) barely change with the layout change.

More specifically, the commutator is structurally based on three terminals, one being an input or common terminal and the other two being output terminals, each having its own respective head. These three contact heads of the respective terminals are faced by the swivel-mounted conductor strap which is logically provided with the three contact heads facing the former.

One such conductor strap contact head permanently rests on the respective common terminal contact head, and this is due to the strength exerted thereupon by an open helical spring, with the added peculiarity that this spring urges such conductor strap towards a stable position where a second contact head contacts one of the output terminals.

The assembly comprises a driving lever, driven either by means of a rotating cam, capable of moving the conductor strap so that, overcoming the open spring strength, it is able to disengage the strap and output terminal contact heads, opening the respective circuit and, if so provided, continuing to move the same to close the respective circuit at the second output terminal.

The assembly further comprises an auxiliary lever attached to the actual conductor strap, through which the helically wound spring strength is transmitted to both said conductor strap and said driving lever, and thus the lever stroke is transmitted to the strap itself.

According to this new commutator conception it suffices to arrange the opposite orientation of the assembly formed by the conductor strap, the auxiliary lever and the helically wound spring in the support element to successfully alter a common terminal to an output terminal or to turn an output terminal into a common terminal.

In the case of switches, the only difference is, compared with commutators, that such switches will not be provided with one of the two output terminals.

In order to provide a full description and contribute to the complete understanding of the characteristics of this invention, a set of drawings is attached to the specification which, while purely illustrative and not fully comprehensive, shows the following:

Figure 1.- Is a cross-section of a commutator made according to the invention, at rest and with the common terminal on the left-hand side.

Figure 2.- Is the same view as the previous figure, but with the commutator in an intermediate working where only one of the strap conductor heads contacts the position corresponding common or input terminal conductor head.

Figure 3.- Is the same view as the previous two figures, in a final working position where two of the strap heads contact the common input terminal and one of the output terminals.

Figure 4.- Is different view of the commutator with the common terminal on the right-hand side and in an intermediate working position, or in other words, opposed to that of figure 2.

Figure 5.- Is a detail of a profile section of the conductor strap to which the relevant auxiliary lever is attached.

Figure 6.- Is a detail of the practical coupling between the conductor strap and the driving lever, as well as the respective open helically wound spring. The enlarged detail shown in circle "A" has been taken from this figure.

Figure 7.- Finally shows several modules placed on top of each other including the conductor strap guided and positioned within each of them.

In the light of these figures, and particularly of figures 1 to 4, the commutator comprises an insulating housing body (1) provided with three terminals (2-2′-2˝) fitted with the respective contact heads (3-3′-3˝), facing the same number of conductor strap (5) contact heads (4-4′-4˝), on which rests an auxiliary lever (6) defining an upper arm (7) and a lower arm (8), such upper arm (7) backed and superimposed to the actual conductor strap (5) whereas the lower arm is arranged parallel with respect to conductor strap (5), though distanced from the same, with the peculiarity that said two arms (7) and (8) are stiffly locked to each other by means of a reinforcement element (9).

The commutator assembly is comprises a driving lever (10), push-button or any other like element, from which projects a feeler (11) which rests on the stepped surfaces (12-12′-12˝) of a cam (13) rotating in the direction of the rrow referenced as (14) in figure 1. In other words, whenever the cam (13) rotates, the feeler (11) can rest upon the surface of smaller diameter (12), average diameter (12′) or larger diameter (12˝), so that in any one of these positions the driving lever (10) will swing to a greater or lesser extent to act on the conductor strap (5) through the auxiliary lever.

Figure 1 shows how the conductor heads (3) and (3˝) of the terminals (2) and (2˝) are in contact with contact heads (4) and (4˝) of conductor strap (5), the device being at rest, this being so because an helically wound spring (15) provided between the body (1) and the conductor strap (5), resting on the upper surface of arm (7) of the auxiliary lever (6), holds such strap (5) in the position, as shown in such figure 1.

This figure 1 also shows that said spring (15) is placed on the commutator's left-hand side or area, ensuring that terminal (2), which is also located on that left-hand side, is in turn the common or current input terminal.

From this position, when the driving lever (10) feeler (11) moves on to the cam (13) intermediate or upper stepped surfaces (12′) and (12˝), the rib (16) on the actual driving lever (10) will urge the auxiliary lever (6), moving the same against the strength exerted by the helically wound spring (15) on the same, whereupon the conductor strap (5) itself moves to lead said parts to the positions shown in figures 2 and 3, in which positions the feeler (11) is on the cam (13) intermediate (12′) and high (12˝) stepped surfaces, respectively.

The auxiliary lever (6) and the conductor strap (5) are functionally coupled to each other so that both the spring (15) strength and the rib (16) movement are transmitted to the strap through said lever (6), this being achieved because said lever (6) has the aforesaid two arms (7) and (8). It can be seen that the upper arm (7) rests on the conductor strap (5), because of the spring (15) strength.

The free end (17) of the upper arm (7) extends beyond the contact head (4), the distance of extension corresponding to the stretch comprised between the two arrows marked as (18), while the lower arm (8) is spaced away from the conductor strap (5) and arranged parallel to the same.

When the commutator is in the positions shown in figures 2 and 3, the auxiliary lever (6) tends to swing at an angle with regard to the conductor strap (5), resting on the upper arm's (7) free end (17) and tending to take up the position shown in figure 6.

Such circumstance leads to the appearance of a resultant force applied to the free end (17), which in figure 6 is marked R, and the magnitude of which is calculated by :$$\text{R =}\frac{\text{F . d}}{\text{D}}$$
where F is the compression force exerted by the spring (15) "D" and "d" being the respective distances between the points where R and F are applied and the support point (16) of the driving lever (10). The resultant force R in turn leads to the appearance of a turning moment marked M in this figure 6, the magnitude of which being determined by :$$\text{M = R x L}$$
where L is the distance between the free end (17) and the swing axis of the strap (5) which is the contact point (3,4), which moment acts on the actual strap (5), causing the same to swing on its support and specifically on its conductor head (3), following the auxiliary lever's (6) angle displacement, and hence remaining joined to the latter's upper arm (7).

Figure 3 shows a positioning of the commutator-switch where the rib (16) of the driving lever (10) pushes the conductor strap (5) by means of the auxiliary lever (6) which is joined to the conductors (3′) of the fixed terminal and the contact head (4′) of the conductor strap (5) between them. While the central contact heads (3′) and (4′) are not engaged, as shown in fig. 2, the auxiliary lever (6) does not disengage the strap (5), but when they are, disengaged it will swing with respect to the strap (5) thereby providing the suffered strain between the auxiliary lever (6) and the conductor strap (5) and the strength between the contact heads (3′) and (4′) which will allow the absorption of the dimensional variations and wears in the switch assembly.

Figure 4 shows how the conductor strap (5) and auxiliary lever (6) parts and the spring (15) that used to be on the left-hand side have now been disposed on the right-hand side or area of the housing (1). In that case the terminal (2˝) now becomes the input or common terminal and terminals (2) and (2′) become the output terminals, the other elements remaining where they were. It means that the only thing that changes is the conductor strap, auxiliary lever and spring assembly positioning so that in the new commutator layout and operation, the input and output terminal can be interchanged depending of the user's wishes.

Transformation of said commutator into a switch will take place by leaving out one of the output terminals, locating the common terminal on the right or left-hand side.

Figure 7 shows how the conductor strap (5) is held in the correct longitudinal position by its wider end part (19) held between the insulating box (22) walls (20) and (21) and is transversely guided by the partition walls (21). The auxiliary lever (6), and particulary branch (7), is provided with a rim (23), see figure 5, which penetrates a slot (24) in the conductor strap (5), which is moreover provided with a recess (25) through which the lever (6) central reinforcement (9) passes.

It finally remains to be said that the structure described or driving device it constitutes, can have a modular configuration, so that-whenever several units are required for a given use whatever number of modules are deemed appropriate, are piled on top of each other, as clearly shown in figure 7, each module comprising a box (22) made of insulating material (preferably molded plastics), where all those parts the commutator or switch consists of, are mounted. Obviously, the commutator module stack comprises the corresponding guiding and attachment means.