EP2232516B1 - Electrical apparatus such as a switch - Google Patents

Description

FIELD OF THE INVENTION

The present invention generally relates to electrical appliances of the kind comprising a first connection terminal; a fixed contact electrically connected to said first connection terminal; a second connection terminal; a mobile contact; a conductive broom carrying said movable contact and electrically connected to said second connection terminal; an elastic member for biasing said brush towards one or the other of two stable positions, respectively a conduction position where said movable contact is applied against said fixed contact and an isolation position where said moving contact is away from said fixed contact; and an actuator mechanically connected to said conductive broom.

BACKGROUND

We already know, especially by French patents FR 2 564 234 and FR 2,606,208 such electrical appliances.

In operation, these devices are almost inevitably noise generating, to the detriment of the surrounding comfort.

Essentially, the noise starts when the moving contact abuts against the fixed contact, which happens in practice abruptly. This results in a more or less loud noise that spreads quickly to the rest of the device.

In order to reduce the noise thus generated, the French patent FR 2,698,719 proposes to provide an elastically deformable tab that provides momentary braking of the movable contact before the abutment with the fixed contact. Such an electrical apparatus is also known from the document DE 43 26 312 A1 .

OBJECT OF THE INVENTION

The invention aims to further improve the comfort of use of such a device.

• une première borne de raccordement ;
• un contact fixe relié électriquement à ladite première borne de raccordement ;
• une deuxième borne de raccordement ;
• un contact mobile ;
• un balai conducteur portant ledit contact mobile et relié électriquement à ladite deuxième borne de raccordement ;
• un élément élastique pour solliciter ledit balai vers l'une ou l'autre de deux positions stables, respectivement une position de conduction où ledit contact mobile est appliqué contre ledit contact fixe et une position d'isolement où ledit contact mobile est à l'écart dudit contact fixe ; et
• un organe de manoeuvre lié mécaniquement audit balai conducteur ;

caractérisé en ce que ledit appareil comporte en outre :

• une paroi fixe ;
• une paroi mobile liée mécaniquement audit balai, ladite paroi fixe et ladite paroi mobile étant agencées pour être animées d'un mouvement relatif lorsque ledit balai se déplace de l'une à l'autre des dites position de conduction et position d'isolement ; et
• une substance fluide visqueuse prise en sandwich entre ladite paroi fixe et ladite paroi mobile dans chacune des dites position de conduction et position d'isolement ainsi que dans chaque position intermédiaire entre celles-ci.

It proposes for this purpose an electrical apparatus comprising:

• a first connection terminal;
• a fixed contact electrically connected to said first connection terminal;
• a second connection terminal;
• a mobile contact;
• a conductive broom carrying said movable contact and electrically connected to said second connection terminal;
• an elastic member for biasing said brush towards one or the other of two stable positions, respectively a conduction position where said movable contact is applied against said fixed contact and an isolation position where said moving contact is away from said fixed contact; and
• an operating member mechanically linked to said conductive broom;

characterized in that said apparatus further comprises:

• a fixed wall;
• a movable wall mechanically bonded to said blade, said fixed wall and said movable wall being arranged to be driven relative movement when said blade moves from one to the other of said conduction position and isolation position; and
• a viscous fluid substance sandwiched between said fixed wall and said movable wall in each of said conduction position and isolation position and in each intermediate position therebetween.

The viscous fluid substance moderates the speed of approach of the moving contact and therefore allows an attenuation of the impact between the movable contact and the fixed contact, which prevents any untimely rebound of the contact mobile potentially generating electric arcs causing degradation of contacts by micro-fusion.

This attenuation of the shock also causes a strong attenuation of the noise generated and more generally a smooth operation, while flexibility, particularly comfortable.

In addition, the damping viscous fluid substance has the advantage of not influencing the pressure exerted between the fixed contact and the movable contact in the conduction position. Indeed, in this abutment position, the moving contact is immobile (zero speed) and no fluid friction force disturbs the action of the elastic element.

Generally speaking, this fluid friction force is proportional to the surface value of the smallest of the fixed and mobile walls sandwiching the fluid substance, to the dynamic viscosity of the fluid substance, to the speed of the relative movement between these two walls, and inversely proportional to their distance with respect to each other, these parameters being chosen as a function of the return force of the spring and the smooth operation desired.

• dans chacune des dites position de conduction et position d'isolement ainsi que dans chaque position intermédiaire entre celles-ci, la substance fluide visqueuse mouille une surface de ladite paroi fixe et une surface de ladite paroi mobile qui sont en regard et à écart sensiblement constant l'une de l'autre ;
• ladite surface mouillée de ladite paroi fixe et ladite surface mouillée de ladite paroi mobile sont planes ;
• ladite surface mouillée de ladite paroi fixe et ladite surface mouillée de ladite paroi mobile sont incurvées ;
• ledit appareil électrique comporte un bac contenant ladite substance fluide visqueuse, et une pale plongée dans ledit bac, ledit bac et ladite pale comportant ladite paroi fixe pour l'un et ladite paroi mobile pour l'autre ;
• ladite pale comporte ladite paroi mobile et ledit bac comporte ladite paroi fixe ;
• ladite pale est liée rigidement à un élément latéral dudit organe de manoeuvre ;
• ladite pale est formée d'une seule pièce avec ledit organe de manoeuvre ;
• ledit bac comporte deux parois formant respectivement une première dite paroi fixe et une seconde dite paroi fixe entre lesquelles est disposée ladite pale comportant ladite paroi mobile ;
• ledit appareil électrique comporte en outre dudit bac, un autre bac semblable et dans lequel est disposée une autre pale semblable à ladite pale ;
• ledit bac et ledit autre bac sont disposés de part et d'autre dudit organe de manoeuvre ; et/ou
• ledit organe de manoeuvre est une touche formée d'une seule pièce avec deux dites pales situées de part et d'autre de ladite touche, chacune des dites pales étant plongée dans un bac respectif contenant ladite substance fluide visqueuse.

According to preferred features for reasons of simplicity and convenience both in manufacture and use:

• in each of said conduction position and isolation position as well as in each intermediate position therebetween, the viscous fluid substance wets a surface of said fixed wall and a surface of said movable wall which are opposite and at a substantially constant distance one from the other ;
• said wet surface of said fixed wall and said wet surface of said movable wall are planar;
• said wet surface of said fixed wall and said wet surface of said movable wall are curved;
• said electrical apparatus comprises a tank containing said viscous fluid substance, and a blade immersed in said tank, said tank and said blade having said fixed wall for one and said movable wall for the other;
• said blade comprises said movable wall and said tray comprises said fixed wall;
• said blade is rigidly connected to a lateral element of said operating member;
• said blade is formed in one piece with said actuator;
• said tank comprises two walls respectively forming a first said fixed wall and a second said fixed wall between which is disposed said blade comprising said movable wall;
• said electrical apparatus further comprises said tray, another similar tray and in which is disposed another blade similar to said blade;
• said tray and said other tray are disposed on either side of said operating member; and or
• said operating member is a button formed in one piece with said two blades located on either side of said key, each of said blades being immersed in a respective tray containing said viscous fluid substance.

BRIEF DESCRIPTION OF THE DRAWINGS

• la figure 1 est une vue simplifiée en perspective d'un appareil électrique selon l'invention ;
• la figure 2 est une vue semblable à la figure 1, mais où la partie située à droite du plan V-V a été arrachée ;
• la figure 3 est une vue semblable à la figure 1, prise selon un angle de vue légèrement différent, où l'organe de manoeuvre est à l'écart du reste de l'appareil ;
• la figure 4 est une vue simplifiée en perspective de l'ensemble comportant le balai conducteur et le berceau sur lequel ce balai est articulé ;
• les figures 5 et 6 sont des vues simplifiées en coupe de l'appareil de la figure 1 suivant les plans repérés respectivement par V-V et par VI-VI ;
• la figure 7 est un agrandissement du détail VII de la figure 6 ;
• la figure 8 est une vue simplifiée en perspective d'un appareil électrique selon une variante de l'invention ; et
• la figure 9 est une vue agrandie et en perspective d'un élément de l'appareil électrique selon la variante de la figure 8.

The description of the invention will now be continued by the detailed description of an exemplary embodiment, given below by way of illustration but without limitation, with reference to the appended drawings, in which:

• the figure 1 is a simplified perspective view of an electrical apparatus according to the invention;
• the figure 2 is a view similar to the figure 1 but where the part to the right of the VV plane has been torn off;
• the figure 3 is a view similar to the figure 1 , taken at a slightly different angle of view, where the operating member is away from the rest of the apparatus;
• the figure 4 is a simplified perspective view of the assembly comprising the conductive broom and the cradle on which the broom is hinged;
• the Figures 5 and 6 are simplified sectional views of the device of the figure 1 according to the plans marked respectively by VV and VI-VI;
• the figure 7 is an enlargement of detail VII of the figure 6 ;
• the figure 8 is a simplified perspective view of an electrical apparatus according to a variant of the invention; and
• the figure 9 is an enlarged and perspective view of an element of the electrical apparatus according to the variant of the figure 8 .

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

The electrical apparatus 1 illustrated on the Figures 1 to 7 is a switch back and forth which comprises a key 60 pivotally mounted on a housing 3, a first fixed contact 4A ( figure 5 ) disposed on the housing 3, a second fixed contact 4B also disposed on the housing 3 and located opposite the first fixed contact 4A, and a movable contact 5 rigidly connected with the key 60.

• une première position où il est appliqué contre le premier contact fixe 4A et se trouve à l'écart du second contact fixe 4B ; et
• une seconde position illustrée sur la figure 5, où il est appliqué contre le second contact fixe 4B et se trouve à l'écart du premier contact fixe 4A.

The moving contact 5 is adapted to occupy alternately two stable positions:

• a first position where it is applied against the first fixed contact 4A and is away from the second fixed contact 4B; and
• a second position illustrated on the figure 5 , where it is applied against the second fixed contact 4B and is away from the first fixed contact 4A.

The housing 3 comprises a generally flat front wall 10 of rectangular shape which has in the central part a recess 11.

This recess 11 is delimited by two opposite longitudinal walls 12A and 12B, two transverse walls 13A and 13B also facing each other and a bottom wall 14 (FIG. figure 3 ). Of generally parallelepipedal shape, the recess 11 has a slightly length less than that of the front wall 10 and a width equal to about one third of that of the same wall 10.

The longitudinal wall 12A (respectively 12B) is extended opposite the recess 11 (thus projecting from the front wall 10) by a flange 15A (respectively 15B).

The bottom wall 14 has a central portion 16 disposed parallel to the front wall 10 and has a central recess 17 of square shape.

The central portion 16 is extended on either side by two lateral portions 18 and 19 inclined in a direction opposite to the front wall 10 and which respectively join the transverse walls 13A and 13B.

The longitudinal walls 12A, 12B and the transverse walls 13A, 13B extend beyond the recess 11 at the side portions 18 and 19 to accommodate the connection terminals 20, 21A and 21B.

The connection terminals 20 and 21A are arranged side by side and close to the transverse wall 13A, while the connection terminal 21B is disposed opposite the terminal 21A and near the transverse wall 13B.

The housing 3 also comprises, vertically above the central portion 16, a rear element 22.

This rear element 22 comprises two walls 23A and 23B facing one another and which extend parallel to the transverse walls 13A and 13B, respectively along the connection terminals 20, 21A and 21 B.

The two walls 23A and 23B of the element 22 are connected to one another by a wall 24 which extends parallel to the central portion 16 of the bottom wall 14.

In order to allow rapid connection of the conductors concerned, the connection terminals 20, 21A and 21B are automatic insertion terminals but alternatively, the latter are of a different type, for example connection terminals with hole and screw.

In the embodiment shown, the terminal 20 is electrically connected to the movable contact 5 rigidly connected to the key 60, the terminal 21A is electrically connected to the fixed contact 4A and the terminal 21 B is connected to the fixed contact 4B. The contacts 4A and 4B are arranged facing each other, on either side of the movable contact 5 and respectively against the walls 23A and 23B.

The fixed contact 4A (respectively 4B) located at one end of a bendable conductive strip 25A (respectively 25B), has a contact bump 26A (respectively 26B) protruding from this strip 25A (respectively 25B).

The other end of the strip 25A (respectively 25B) is connected to the terminal 21A (respectively 21B).

For use as a single switch, one of the terminals 21A or 21B and the corresponding fixed contact 4A or 4B are omitted or unused.

A metal cradle 30 (see more particularly the figure 4 ) is disposed on the periphery of the recess 17. It comprises two triangular panels 31A and 31B disposed facing one another and extending parallel to the longitudinal walls 12A and 12B in the direction of the front wall 10. Each triangular panels 31A and 31B have at its apex a notch 32A, 32B.

The cradle 30 also comprises two crosspieces 33 and 34 respectively connecting the first and second ends of the bases of the triangular panels 31A and 31B.

The crosspiece 33 is connected to a tongue 35 which extends in the direction of the transverse wall 13A against the lateral portion 18 of the bottom wall 14. A tab 36 which takes root in the central zone of the tongue 35 extends through the lateral portion 18, to the connection terminal 20 to which it is electrically connected by welding or punching.

A finger 37 extends from the central portion of the crosspiece 34 towards the crosspiece 33 and the bottom wall 14, the distal end of the finger 37 having a notch 38.

A flat conductor blade 40 comprising the movable contact 5 is provided to articulate with the cradle 30 of the housing 3.

This conductive broom 40 comprises a head 41 provided with a notch 42 overhanging a shoulder 43 from which extend, in the direction of the recess 11, two legs 44A and 44B whose distal ends are joined by a chevron 45 constituting the moving contact. 5 and whose tip is oriented towards the wall 24. Near its tip, the chevron 45 has on each of its faces, a contact grain 46A, 46B. The conductive broom 40 also comprises two pins 47A and 47B which project on either side of the shoulder 43, and which are adapted to cooperate with the notches 32A, 32B so as to make a pivot connection of the conductive mop 40 with respect to the cradle 30.

Maintaining the conductive broom 40 on the cradle 30 is provided by a spring 48 having a central helical portion protruding from both sides hooks respectively engaged with the notch 38 of the finger 37 and with the notch 42 of the head 41.

On the figure 4 , the spring 48 occupies an unstable position in which the distance between the two hooks is maximum. In practice, this spring 48 tends to occupy a more retracted position by rotating the blade 40 to bring it to a first position in which the grain 46A of the movable contact 5 is in electrical contact with the grain 26A of the fixed contact 4A or in a second position in which the grain 46B of the movable contact 5 is in electrical contact with the grain 26B of the fixed contact 4B ( figure 5 ).

The two longitudinal walls 12A and 12B of the recess 11 respectively project, two trays 50A, 50B similar and arranged opposite one another.

The tray 50A (respectively 50B) is delimited by the longitudinal wall 12A (respectively 12B), a longitudinal longitudinal wall 51A (respectively 51B) parallel to the side wall 12A (respectively 12B), two flat transverse walls 52A (respectively 52B) and 53A (respectively 53B) also parallel, and a flat bottom wall 54A (respectively 54B).

Of parallelepipedal shape, the tray 50A (respectively 50B) extends along the central portion of the side wall 12A (respectively 12B), since the free end of the flange 15A (respectively 15B) and towards the bottom wall 14.

The inner wall 51A (respectively 51B) has at its free end 55A (respectively 55B) located at the front wall 10, a rectangular central recess 56A (respectively 56B).

The tray 50A (respectively 50B) contains a volume of a viscous fluid substance 57A (respectively 57B) such as grease or silicone gel. This substance 57A (respectively 57B) has a sufficiently high dynamic viscosity so that it does not flow from the tanks 50A and 50B regardless of their spatial orientation. The substance 57A (here identical to the substance 57B) is relatively stable over time so that its viscosity remains constant or approximately during the life of the electrical appliance 1, independently of the mechanical stresses exerted on it. .

The key 60 has two longitudinal walls 61A, 61B planar and parallel to each other, two end walls 62A, 62B curves facing one another and a plate 63 slightly concave. The longitudinal wall 61A (respectively 61B) has in its central part, a slot (not visible in the figures relating to this embodiment, but similar to the slot 64B 'of the variant illustrated in FIG. figure 9 which will be described later). This slot extends from its free edge 65A (respectively 65B) towards the plate 63 and about half of its width.

On either side of the key 60 extend two lateral elements 66A and 66B.

The lateral element 66A (respectively 66B) comprises a hemi-circular section wall 67A (respectively 67B) which takes root on the outer face of the longitudinal wall 61A (respectively 61B) at the level of the inner end of the slot 64B and extending transversely to the longitudinal wall 61A (61 B respectively).

The lateral element 66A (respectively 66B) also comprises a blade 68A (respectively 68B) which extends parallel to the longitudinal wall 61A (61 B respectively), from the distal end of the hemi-circular section wall 67A (respectively 67B) . This blade 68A (respectively 68B) has a wall 69A (respectively 69B) which has a thickness slightly less than the internal width of the tray 50A (respectively 50B).

As we see more particularly on the figure 5 , the wall 69B comprises two portions 70B and 71B. The portion 70B has a triangle-shaped profile, here isosceles, and extends in the direction of the free edge 65B of the longitudinal wall 61 B. The top 72B of this first triangular portion 70B merges with the distal end of the wall 67B while its base 73B is parallel to the free edge 65B.

The second portion 71 B which has a half-disk contour, extends from the central zone of the base 73B of the first triangular portion 70B, in the opposite direction to the vertex 72B of the same triangular portion 70B.

The wall 69 A is similar to the wall 69B.

The introduction of the key 60 on the housing 3 is effected by inserting the shoulder 43 of the conductive broom 40 in the slots such as 64B 'of the longitudinal walls 61A, 61B to the stop position.

At the same time, the blade 68A (respectively 68B) enters the tray 50A (respectively 50B) and plunges into the viscous fluid substance 57A (respectively 57B).

Once assembly is complete, the inner surface of the plate 63 is close to the head 41 of the conductive broom 40, while the hemi-circular section wall 67A (respectively 67B) is located at the level of the rectangular recess 56A (respectively 56B) of the inner wall 51A (51 B respectively).

As for the blade 68A (respectively 68B), it is almost completely immersed in the tray 50A (respectively 50B) in contact with the viscous fluid substance 57A (respectively 57B).

When the key 60 moves from one to the other of the two stable positions, the blade 68A (respectively 68B) moves between and parallel to the two longitudinal walls 12A (respectively 12B) and 51A (respectively 51B) of the tray 50A (respectively 50B).

On each side of the wall 69A (respectively 69B) and for each of the two stable positions as well as intermediate positions, a volume of viscous fluid substance 57A (respectively 57B) is found sandwiched between this wall and, on one side, the longitudinal wall 12A (respectively 12B) and, on the other side, the longitudinal wall 51A (51 B respectively).

As is clearly visible on the figure 7 , the volume of viscous fluid substance 57B located between the longitudinal wall 12B (respectively 51B) and the wall 69B, wets a surface 75B (respectively 77B) of the inner face of this longitudinal wall 12B (respectively 51B) and a surface 76B (78B respectively) of the face of the wall 69B facing the surface 75B (respectively 77B), the gap between these two surfaces 75B (respectively 77B) and 76B (respectively 78B) remaining substantially constant.

When moving the blade 68B in the tray 50B, the fluid substance layer 57B in contact with the wetted surface 75B (respectively 77B) and the fluid substance layer 57B in contact with the wetted surface 76B (respectively 78B) exert the one on the other a fluid friction force.

This fluid friction force is proportional to the wet surface 76B (respectively 78B) of the blade 68B, the viscosity of the viscous fluid substance 57B and the speed of the blade 68B, and inversely proportional to the distance between the wet surfaces.

The description that has just been made for blade 68B in support of figure 7 also applies to the blade 68A by replacing the suffixes "A" by the suffixes "B".

Thanks to the fluid friction forces, the blades 68A and 68B, and therefore the key 60, the blade 40 and the movable contact 5 have a speed of displacement, under the effect of the spring 48, which remains moderate, so that the switch is particularly comfortable to use.

The switch 1 'illustrated on the Figures 8 and 9 , is similar to switch 1 except that the side elements of the key and the bins are shaped differently. In the continuation and on the drawings, one kept the same references for the identical elements and with a premium for the similar elements.

The blade 68B 'has a portion of rectangular contour 80B' which extends parallel to the longitudinal wall 61B ', towards its free edge 65B'. The blade 68B 'also comprises a curved pad 81B' which takes root at the distal end of the rectangular contour portion 80B 'and extends transversely thereto in a direction opposite to that of the key 60'.

The tray 50B 'has a greater width to accommodate the pad 81 B' while its bottom wall is curved and is coated with a viscous fluid substance.

The length of the rectangular profile portion 80B 'is chosen so that once assembly is complete, the pad 81 B' is close to the bottom wall of the tray 50B 'in contact with the viscous fluid substance.

When moving the key 60 'from one to the other of the two stable positions, the shoe 81 B' describes a rocking movement.

In each of these two stable positions and in each intermediate position between them, a volume of viscous fluid substance is thus sandwiched between the bottom wall of the tray 50B 'and the pad 81 B' of the blade 68B ' .

This volume of viscous fluid substance wets a surface of the inner face of the bottom wall of the tray 50B 'and a surface of the face of the skid 81 B 'facing the surface of the inner face of the bottom wall of the tray 50B', the gap between these two surfaces remaining substantially constant.

In a variant not shown, the blade 68A (respectively 68B) (just like the key 60 to which it is rigidly connected) describes a rectilinear and non-rotating movement.

In another variant not shown, the tray such as 50A or 50B is linked in motion with the key such as 60, the blade such that 68A or 68B is fixed.

• les bacs tels que 50A, 50B et les pales telles que 68A, 68B sont de plus grandes (respectivement plus petites) dimensions afin d'augmenter (respectivement de diminuer) l'étendue des surfaces mouillées telles que 75B, 76B et donc la force de frottement fluide générée ;
• la profondeur des bacs tels que 50A, 50B et la longueur des pales telles que 68A, 68B sont augmentées (respectivement diminuées) pour éloigner (respectivement rapprocher) les portions des pales 68A, 68B en contact avec les substances fluides visqueuses telles que 57A, 57B de l'axe de rotation de la touche telles que 60, et ainsi augmenter (respectivement diminuer) la vitesse des portions mouillées des pales telles que 68A, 68B et donc la force de frottement fluide générée ; et/ou
• les substances fluides visqueuses telles que 57A, 57B présentent des viscosités dynamiques supérieures (respectivement inférieures) ce qui a pour effet une augmentation (respectivement une diminution) de la force de frottement fluide générée.

In yet other variants not shown in which the restoring force of the spring such as 48 is greater (respectively lower):

• bins such as 50A, 50B and blades such as 68A, 68B are larger (respectively smaller) dimensions to increase (respectively decrease) the extent of wet surfaces such as 75B, 76B and therefore the force of fluid friction generated;
• the depth of the tanks such as 50A, 50B and the length of the blades such as 68A, 68B are increased (respectively decreased) to move (respectively closer) the portions of the blades 68A, 68B in contact with the viscous fluids such as 57A, 57B the axis of rotation of the key such as 60, and thus increase (respectively decrease) the speed of the wet portions of the blades such as 68A, 68B and therefore the fluid friction force generated; and or
• the viscous fluids such as 57A, 57B have higher (respectively lower) dynamic viscosities, which has the effect of increasing (respectively decreasing) the fluid frictional force generated.

In still other variants not shown, the electrical apparatus is different from a switch for example a remote switch.

Claims (12)

1. Electrical apparatus including:

   - a first connection terminal (21A, 21B);

   - a fixed contact (4A, 4B) electrically connected to said first connection terminal (21A, 21B);

   - a second connection terminal (20);

   - a mobile contact (5);

   - a conductive wiper (40) carrying said mobile contact (5) and electrically connected to said second connection terminal (20);

   - a spring component (48) for urging said wiper (40) toward one or the other of two stable positions, specifically a conducting position in which said mobile contact (5) is on said fixed contact (4A, 4B) and an isolating position in which said mobile contact (5) is not on said fixed contact (4A, 4B); and

   - a control member (60) mechanically connected to said conductive wiper (40);

   characterized in that said apparatus further includes:

   - a fixed wall (12A, 12B, 51A, 51B);

   - a mobile wall (69A, 69B, 81B') mechanically connected to said wiper (40), said fixed wall (12A, 12B, 51A, 51B) and said mobile wall (69A, 69B, 81B') being arranged so as to have a relative movement imparted to them when said wiper (40) moves from one to the other of said conducting and isolating positions; and

   - a viscous fluid substance (57A, 57B) sandwiched between said fixed wall (12A, 12B, 51A, 51B) and said mobile wall (69A, 69B, 81B') in each of said conducting and isolating positions and in each intermediate position between the latter.
2. Electrical apparatus according to claim 1, characterized in that in each of said conducting and isolating positions and in each intermediate position between them, the viscous fluid substance (57A, 57B) wets a surface (75B, 77B) of said fixed wall (12A, 12B, 51A, 51B) and a surface (76B, 78B) of said mobile wall (69A, 69B) that are opposite each other and at a substantially constant distance from each other.
3. Electrical apparatus according to claim 2, characterized in that said wetted surface (75B, 77B) of said fixed wall (12A, 12B, 51A, 51B) and said wetted surface (76B, 78B) of said mobile wall (69A, 69B) are plane.
4. Electrical apparatus according to claim 2, characterized in that said wetted surface of said fixed wall and said wetted surface of said mobile wall (81B') are curved.
5. Electrical apparatus according to any of claims 1 to 4, characterized in that said electrical apparatus includes a tank (50A, 50B, 50B') containing said viscous fluid substance (57A, 57B) and a paddle (68A, 68B, 68B') immersed in said tank (50A, 50B, 50B'), one of said tank (50A, 50B, 50B') and said paddle (68A, 68B, 68B') including said fixed wall (12A, 12B, 51A, 51B) and the other of them including said mobile wall (69A, 69B, 81B').
6. Electrical apparatus according to claim 5, characterized in that said paddle (68A, 68B, 68B') includes said mobile wall (69A, 69B, 81B') and said tank (50A, 50B, 50B') includes said fixed wall (12A, 12B, 51A, 51B).
7. Electrical apparatus according to claim 6, characterized in that said paddle (68A, 68B, 68B') is rigidly joined to a lateral member (67A, 67B) of said control member (60).
8. Electrical apparatus according to claim 7, characterized in that said paddle (68A, 68B, 68B') is formed in one piece with said control member (60).
9. Electrical apparatus according to any of claims 6 to 8, characterized in that said tank (50A, 50B) includes two walls (12A, 12B, 51A, 51B) respectively forming a first said fixed wall (12A, 12B) and a second said fixed wall (51A, 51B) between which is disposed said paddle (68A, 68B) including said mobile wall (69A, 69B).
10. Electrical apparatus according to claim 9, characterized in that it further includes in addition to said tank (50A) another similar tank (50B) in which is disposed another paddle (68B) similar to said paddle (68A).
11. Electrical apparatus according to claim 10, characterized in that said tank (50A) and said other tank (50B) are on opposite sides of said control member (60).
12. Electrical apparatus according to claim 11, characterized in that said control member (60) is a rocker formed in one piece with said two paddles (68A, 68B) on either side of said control member (60), each of said paddles (68A, 68B) being immersed in a respective tank (50A, 50B) containing said viscous fluid substance (57A, 57B).

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