EP0866483A1 - Bistable battery switch with mechanical interlock - Google Patents

Abstract

The cut-out comprises a casing with at least two electrical contact pins, transversal contact bridge and operating devices. The transversal contact bridge (5) is located above the contact pins and drive devices are provided for the bridge which establish or suppress electrically the connection between the contact pins. The drive devices incorporate an axially mobile component working in conjunction mechanically with the transversal contact bridge. A fixed electrical coil (6) generates an electromagnetic force acting axially on the mobile component towards the contact pins and stop devices define two stable conditions of the bridge i.e. ON/OFF related to the circuit cut-out. The stop devices have a fixed part with an indexation digit (19) extending towards the interior from its bore and the mobile part comprises upper (20) and lower (21) ramps.

Description

The present invention relates to a circuit breaker used as safety means for an electrical circuit.

Circuit breakers are commonly used as battery cutouts equipping vehicles, in particular transport vehicles of hazardous materials whose safety instructions are very strict.

We know on the market different types of battery switch that can be manual, pneumatic or electromagnetic. The battery switch includes a box, a base provided with at least two electrical contact pads, a bridge transverse contact that can electrically connect the pads contact, an axially movable actuating member which cooperates mechanically with the transverse contact bridge. The organ actuation button enables or removes the connection electric between the contact pads via the transverse contact bridge and thus define the electrical states "ON" and "OFF" of the battery switch.

The classic electromagnetic control battery switches include an excitation coil which surrounds part of the organ mobile actuation. The coil is constantly supplied by a direct current to maintain the cross bridge in contact with the contact pads to ensure the ON electrical state of the circuit breaker. Just remove the excitation current from the coil so that the transverse bridge moves away from the contact pads in thus ensuring the OFF electrical state of the circuit breaker. The bridge transverse contact is kept in the position away from the studs contact by an axial return spring acting on one end of the mobile actuator.

Because of the need for an electric current supplying permanently the excitation coil to keep the battery switch in ON position, the power consumption of the latter is high. In in addition, in the event of a failure of the power supply system electric for the coil, the battery switch is automatically changed to OFF position due to mechanical force exerted on the movable member for actuation by the return spring. Such inadvertent change of electrical state of the battery switch may be serious consequence for the electrical circuit to which the battery switch, since the electrical supply of said circuit is thus interrupted.

We also know from EP-A-0 630 034, a circuit breaker impulse in which the electrical current holding in the excitation coil when the circuit breaker is in a state electric ON or OFF is zero. The circuit breaker includes an axis movable control secured to a transverse roller carrier axis whose ends are provided with rollers capable of cooperating with an upper ramp fixed to a support integral with a carcass metal in which a coil is enclosed, and with a ramp lower fixed to a lower metal support integral with the base. The operation of this circuit breaker is satisfactory. However, we are trying to improve its functioning and reduce its cost by decreasing the number of parts and improving its reliability of operation.

The object of the present invention is to improve this circuit breaker by offering an economical and improved lifespan device.

The circuit breaker according to the invention comprises a housing provided at least two electrical contact pads, a transverse bridge of contact located above the contact pads, and means of the transverse bridge which establish or suppress electrically the connection between the contact pads, the means actuator comprising an axially cooperating movable member mechanically with the transverse contact bridge, a coil fixed electric to generate an electromagnetic force acting axially on the movable member towards the contact pads, a spring reminder acting axially on the movable member away from the studs contact, and stop means defining two stable states of the bridge corresponding to two electrical states ON, OFF, of the circuit breaker. The stop means comprise a part fixed relative to to the circuit breaker box, of hollow cylindrical shape and provided at least one indexing finger projecting inwards from its bore, and a movable part arranged in the bore of the part fixed and comprising an upper ramp and a lower ramp arranged opposite one another and, axially, on either side the indexing finger with which they cooperate. The moving part is free in rotation and integral in translation with the movable member.

The movable part can thus be formed of a one-piece assembly.

In one embodiment, at least one of the ramps comprises at least one guide surface with variable slope. We can thus reduce the impact between the indexing finger and the ramp, which reduces the wear of these parts and increases the life of the circuit breaker. The guide surface may include two portions of different slope surface.

In one embodiment of the invention, the guide surface is provided on the upper ramp to guide the indexing finger between a first stable position and a second stable position defined by the lower ramp.

Advantageously, the mobile part comprises six portions of ramp, identical, circumferentially distributed and capable of each define two stable states of the bridge corresponding to two states circuit breaker.

We can provide a material of greater hardness or more low coefficient of friction for the indexing fingers which are attached to the hollow cylindrical part of the fixed part of the means stop.

la figure 1 est une vue en coupe axiale d'un coupe-circuit selon l'invention à l'état ouvert;

la figure 2 est une vue en coupe axiale du coupe-circuit à l'état fermé;

la figure 3 est une vue partielle développée de la partie mobile du coupe-circuit de la figure 1 ; et

la figure 4 est une vue en coupe transversale selon IV-IV de la figure 2;

The invention will be better understood on studying the detailed description of a particular embodiment taken by way of nonlimiting example and illustrated by the appended drawings, in which:

Figure 1 is an axial sectional view of a circuit breaker according to the invention in the open state;

Figure 2 is an axial sectional view of the circuit breaker in the closed state;

Figure 3 is a partial developed view of the movable part of the circuit breaker of Figure 1; and

Figure 4 is a cross-sectional view along IV-IV of Figure 2;

As illustrated in the figures, the circuit breaker includes a housing 1 made of rigid non-conductive plastic material electricity, for example in bakelite. The housing 1 is of axial section rectangular and is provided with a bottom wall 2 through which are fixed two electrical output terminals 3 each comprising a electrical contact pad 3a and electrical receiving terminals order information, not shown.

Inside the housing 1 are actuation means 4 for an electric contact bridge 5 in order to move the latter vertically in the drawings. When bridge 5 is in contact with the electrical pads 3a, the electrical terminals 3 are connected between they electrically. Then the circuit breaker is in the electrical ON state, that is to say in the closed position. When the transverse bridge 5 is not in contact with the electrical pads 3a, the electrical terminals 3 do not are more electrically connected to each other. The circuit breaker then finds in the electrical state OFF, that is to say in the open position.

The actuation means 4 of the electric contact bridge 5 comprise a cylindrical coil 6 delimited internally by a cylindrical element 7 made of non-magnetic material, and externally by a metal carcass 8 fixed to a part metallic upper 9.

The non-magnetic cylindrical element 7 delimits a passage vertical cylindrical 7a in which is housed a fixed tubular core 10 whose lower end is in axial abutment on the edges of a central opening 11 of the metal carcass 8. In the passage cylindrical 7a is also a movable core 12 in which is concentrically fixed the upper end of a control shaft 13. The control axis 13 extends vertically through the core fixed 10. Below the central opening 11 of the carcass metal 8 is a movable part 14 of cylindrical shape coaxial with the control axis 13. The control axis 13 extends below the moving part 14 and its lower end passes through the transverse contact bridge 5. Between the transverse contact bridge 5 and the movable part 14 is disposed a helical spring 15 called "spring main contact ". The main spring 15 tends to move the part apart mobile 14 of the transverse contact bridge 5 which can slide axially with respect to the control axis 13. A second spring helical 16 called "return spring" is arranged under the bridge transverse contact 5 between the latter and the bottom wall 2 of the housing 1. Provision is made to electrically isolate the control shaft 13, the main spring 15 and return spring 16 of the transverse bridge of contact 5 by means not shown.

An indexing element 17, of cylindrical shape, is arranged around the moving part 14. The indexing element 17 is secured to the housing 1 by means not shown. The bore 17a of the indexing element 17 is in contact with the external surface 14a of the moving part 14. Two transverse and coaxial holes 18 are provided in the indexing element 17 to each receive a finger indexing 19 partially projecting inwards from the bore 17a of the indexing element 17.

The outer surface 14a of the moving part 14 is provided on all around its hollow forming an upper ramp 20 and a lower ramp 21. The upper 20 and lower 21 ramps are inclined for guiding and locking the moving part 14 by relative to indexing fingers 19.

When the coil 6 is excited by an electric current, it generates a magnetic field whose field lines pass through a magnetic circuit formed by the movable core 12, the fixed core 10, the upper metal support 9 and the metal carcass 8. From this way, an electromagnetic force is created and acts on the nucleus movable 12 axially downward, the control axis 13 secured to the movable core 12 and the movable part 14 then being also driven down.

When starting from an open position of the circuit breaker (Figure 1), the two indexing fingers 19 are pressed against the lower ramp 21 by the return spring 16 in a first stable position P1 (figure 4). An electrical impulse given to the coil 6 causes the movable core 12 towards the fixed core 10. The control axis 13 integral with the movable core 12 moves axially downwards and puts in contact with the electrical bridge 5 with the two contact pads 3a.

The control axis 13 which is guided axially through the bridge electric 5 continues to move downwards overcoming the effort axial of the main spring 15, which then increases the pressure of contact of the transverse bridge 5 on the contact pads 3a.

As can be seen in FIG. 3, the upper ramp 20 includes a strongly inclined guide surface portion 20a extending by a portion of guide surface 20b weakly tilted. A concave rounded portion 20c adjacent to the portion 20b, is of curvature adapted to that of the indexing finger 19 and forms the connection with a stop portion 20d of very steep inclination, close from the vertical. A portion of guide surface 20e is adjacent to the stop portion 20d and makes a sharp angle with it. The portion of guide surface 20e is slightly inclined, substantially as much that the guide surface portion 20b, and is extended by a concave rounded portion 20f of curvature equal to that of the portion rounded 20c. A 20g stopper portion, adjacent to the rounded portion 20f, is connected to the next guide surface portion by a sharp corner. The portions 20a to 20g form part of the ramp upper 20 over an angular sector of 60 °. The upper ramp 20 includes six identical parts, successive every 60 °.

It is the same for the lower ramp 21, part of which on an angle of 60 ° comprises a concave rounded portion 21a forming a stable position P1 for an indexing finger 19 and extending by a strongly inclined abutment portion 21b, a portion of guide surface 21c slightly inclined forming a sharp angle with the abutment portion 21b, a concave rounded portion 21d forming a stable position P3 for an indexing finger 19, a stop portion 21st very steep, close to vertical, and a portion of guide surface 21f strongly inclined and forming a sharp angle with the abutment portion 21st. The guide surface portion 21f is connects to a concave rounded portion of the next part of the lower ramp 21.

When the indexing finger 19 is in position P1 and a electrical impulse is sent to the coil 6, the moving part 14 is driven vertically downwards until the surface portion guide 20a comes into contact with the indexing finger 19. The part mobile 14 is then rotated. As the surface portion of guide 20a is strongly inclined, the aforementioned contact is relatively soft. The guide surface portion 20b then comes into contact with finger 19, which attempts to slow the axial movement of the workpiece mobile 14 due to the small inclination of said portion 20b. The rotation of the moving part 14 stops when the rounded portion 20c and the stop portion 20d come into contact with the indexing finger 19. The latter is then in position P2 and remains there as long as the electrical pulse in coil 6 lasts. electric stops, the moving part 14 moves vertically towards the high under the action of the main spring 15. The surface portion of guide 21c then comes into contact with the indexing finger 19, the moving part 14 being rotated until the portion rounded 21d and the abutment portion 21e come into contact with the finger indexing 19 which is then in the stable position P3. The bridge transverse 5 is then in contact with the pads 3a.

During a subsequent electrical pulse in the coil 6, the moving part 14 is driven vertically downwards until the guide surface portion 20e comes into contact with the finger indexing 19, which causes the moving part to rotate 14 until the rounded portion 20f and the stopper portion 20g come into contact with the indexing finger 19. The latter is then in the P4 position in which it remains until it stops the electrical impulse. The moving part 14 then takes up a vertical upward movement until the surface portion of guide 21f comes into contact with the indexing finger 19, which causes the moving part 14 to rotate until the indexing finger 19 is found in the stable position P1 of the next part of the moving part 14.

Thanks to the invention, a circuit breaker is obtained whose ramps guide can be made in one piece and the smooth operation thanks to the fact that guide surfaces of the ramps are provided with different slopes.

Claims (6)

Circuit breaker comprising a housing (1) provided with at least two electrical contact pads (3a), a transverse contact bridge (5) located above the contact pads, and actuation means of the transverse bridge which electrically establishes or removes the connection between the contact pads, the actuating means comprising a axially movable member mechanically cooperating with the bridge transverse contact, a fixed electric coil (6) to generate a electromagnetic force acting axially on the movable member towards the contact pads, a return spring (16) acting axially on the movable member away from the contact pads, and means of stop defining two stable states of the bridge corresponding to two states electric (ON, OFF) of the circuit breaker and comprising a fixed part (17) relative to the housing of the circuit breaker, of cylindrical shape hollow and a movable part (14) arranged in the bore of the part fixed characterized in that the fixed part comprises at least one index finger (19) projecting inwards from its bore, and that the movable part comprises an upper ramp (20) and a lower ramp (21) arranged opposite one another and, axially on either side of the indexing finger with which they cooperate, said movable part being free to rotate and integral with translation of the movable member. Circuit breaker according to claim 1, characterized in that that the mobile part is in one piece. Circuit breaker according to claim 1 or 2, characterized by fact that at least one of the ramps comprises at least one surface of variable slope guidance. Circuit breaker according to claim 3, characterized in that that said guide surface comprises two surface portions of different slopes. Circuit breaker according to claim 3 or 4, characterized by causes said guide surface to be provided on the upper ramp to guide the indexing finger between a first stable position (P1) and a second stable position (P3) defined by the ramp lower. A circuit breaker according to any one of the claims above, characterized in that the movable part comprises six ramp portions, identical, circumferentially distributed and capable of defining each two stable states of the bridge corresponding to two electrical states of the circuit breaker.

Images