Information
-
Patent Grant
-
6337449
-
Patent Number
6,337,449
-
Date Filed
Wednesday, March 1, 200024 years ago
-
Date Issued
Tuesday, January 8, 200222 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Parkhurst & Wendel, L.L.P.
-
CPC
-
US Classifications
Field of Search
US
- 200 400
- 335 16
- 335 46
- 335 147
- 335 185
- 335 190
- 218 152
- 218 153
-
International Classifications
-
Abstract
A low-voltage limiting circuit breaker comprises a stationary contact part and a movable contact part itself comprising a support pivoting around a fixed axis between a closed position and an open position, a contact finger pivoting around a fixed axis between a non-repelled position and a repelled position, and a bistable device comprising a spring arranged between the support and the finger. When the finger is positioned in its repelled position and the support pivots from its closed position to its open position, it drives the finger to its non-repelled position. A part of the energy necessary to pass the dead point of the bistable device is provided by a spring which urges the support to its open position only at the beginning of opening, which enables the opening spring of the circuit breaker not to be overdimensioned.
Description
BACKGROUND OF THE INVENTION
The invention relates to a low-voltage limiting circuit breaker, and more particularly to a low-voltage limiting circuit breaker of high rating.
The document GB-A-1,564,412 describes a low-voltage limiting circuit breaker of high rating comprising
a case;
an opening mechanism comprising at least one energy storage means;
one or more poles each comprising:
a stationary contact part fixed with respect to the case;
a stop fixed with respect to the case;
a movable contact part comprising:
a support movable relatively to the case between a closed position and an open position;
at least one movable contact finger movable relatively to the support between a non-repelled position and a repelled position;
at least one bistable mechanism comprising a spring arranged between the support and the finger in such a way that it passes via a maximum potential energy when the finger and support are situated in a dead point position relatively to one another, that it tends to urge the finger to its repelled position when the finger is situated relatively to the support between its repelled position and the dead point position, and that it tends to urge the finger to its non-repelled posit ion when the finger is situated relatively to the support between its non-repelled position and the dead point position;
the stop being arranged in such a way that when the finger is positioned in its repelled position and the support moves from its closed position to its open position, the finger, once in contact with the stop, remains in contact therewith until the support passes beyond an intermediate rocking position relatively to the case, corresponding to the relative dead point position with respect to the finger,
the opening mechanism being kinematically linked to the support in such a way as to urge the support to its open position when the support is in its closed position.
The spring of the bistable device performs several functions. It is first of all designed to provide a contact pressure between the stationary contact part and the contact finger when the circuit breaker is closed which pressure is relatively independent from the state of wear and the manufacturing tolerances of the circuit breaker. This contact pressure is moreover determinant for the repulsion threshold beyond which the electromagnetic forces will drive the finger to its repelled position. When the finger has pivoted beyond the dead point, the spring also serves the purpose of confirming repulsion and/or of preventing the finger from rebounding, since it prevents the finger from returning to a non-repelled position. Before the circuit breaker can be closed again, the energy storage means of the opening mechanism has to be released, which drives the bar and, with said bar, the support of the movable contact part to the open position, and which enables the finger to pivot to the non-repelled position by cooperation with the stop.
In such a device, the energy storage means of the opening mechanism has to overcome the resistance of the spring of the bistable device. However this passage should preferably take place at the beginning of opening travel in order to limit the dimensions of the circuit breaker compartment where the contacts are located. The support for its part has to pivot at sufficiently high speed, when passing the intermediate rocking position, for the return force of the spring of the bistable device not to give rise to too great a movement of the finger and the stationary contact towards one another after the dead point has been passed.
Consequently, the spring of the opening mechanism has to simultaneously speed up the support and compress the spring of the bistable device. In energy terms, it has to simultaneously supply the spring of the bistable device with the energy necessary for the latter to reach its maximum potential energy state, and supply the support with the kinetic energy necessary for high-speed movement thereof to the open position. Let us also recall that the spring of the opening mechanism also has to achieve on its own high-speed opening of the circuit breaker in the event of tripping on a weak current surge.
To reconcile these requirements, a powerful opening energy storage means is generally provided. However this solution is not without drawbacks since the energy released on opening has to be dissipated in the end of opening travel stops so that the power of the spring is determinant for the cost and dimensions of the circuit breaker. Furthermore, different opening mechanisms have to be provided depending on the number of poles of the circuit breaker. Let us recall that not only single-pole, three-pole and four-pole circuit breakers are encountered, but also, for high ratings where each phase is connected to two poles in parallel or serially, six-pole or even eight-pole circuit breakers.
The dimensioning problem is even more complicated when identical movable contact parts of the identical fingers and bistable devices, using supports, are designed to equip circuit breakers whose opening mechanisms are of different kinds. It is in fact desirable to be able to equip a range of circuit breakers indifferently with a first type of mechanism in which the energy storage means of the opening mechanism also releases the energy required for closing of the circuit breaker, and with a second type of mechanism, called O-C-O (for open, closed, open) in which a closing energy storage means is loaded independently from the position of the contacts and performs loading of the opening energy storage means simultaneously when closing takes place. However the two types of mechanism have different opening kinematics. We thus generally consider that, for a given opening energy, i.e. for a given opening spring, the O-C-O mechanism operates at lower speed at the beginning of opening travel and at higher speed at the end of opening travel.
SUMMARY OF THE INVENTION
The object of the invention is therefore to overcome the shortcomings of the prior art and in particular to enable movable contact parts with identical bistable mechanisms to be used for limiting circuit breakers whose opening mechanisms have variable characteristics in particular at the beginning of opening travel. Its object is also to enable the opening mechanism of a limiting circuit breaker to be dimensioned regardless of the number of poles. Another object of the invention is to make speeding-up of the support of a movable contact part at the beginning of opening travel relatively independent from the type of opening mechanism implemented. Another object of the invention is to limit the energy to be dissipated at the end of opening travel, without notably increasing either the opening travel or the dimensions of the apparatus. Another object is to reduce the energy required on opening to a minimum.
According to the invention, these objects are achieved by means of a circuit breaker of the above-mentioned type, wherein each pole further comprises an auxiliary mechanism comprising one or more energy storage means urging the support to its open position over all or part of the travel of the support between its closed position and the intermediate rocking position, but no longer urging the support to its open position beyond the intermediate rocking position. The speeding-up at the beginning of opening travel can thus be adjusted by choosing the power of the second energy storage means judiciously.
Preferably the energy storage means of the auxiliary mechanism do not act on the support when the latter is located between its intermediate rocking position and its open position. Beyond the rocking position, the support does not require much energy to reach its open position, so that the energy provided by the second energy storage means is no longer necessary.
Alternatively, an energy storage means can be provided supplying energy to the support over a part of its travel at least between the closed position and the intermediate rocking position and storing energy over at least a part of the travel of the support between the intermediate position and the open position. This energy storage means may for example comprise a spring whose rest position corresponds to the relative rocking position, acting in compression before this position and in traction beyond it. This enables the energy remaining to be dissipated in the end-of-travel stops of the opening mechanism at the end of opening travel to be limited even further.
Preferably, the energy storage means of the auxiliary mechanism of each pole are such that when movement of the movable support of the pole involved takes place, they release an energy greater than or equal to that necessary to move the bistable mechanism(s) of the pole involved to their maximum potential energy. This arrangement is particularly advantageous for a multipole circuit breaker comprising an operating mechanism common to all the poles. It is then in fact easier to dimension the opening spring independently from the number of poles, while limiting the power of said spring.
According to one embodiment, the circuit breaker comprises in addition latching means. This arrangement fosters movement from the intermediate rocking position to the open position. It therefore enables the kinetic energy required for movement from the intermediate rocking position to be limited. This consequently enables the power of the auxiliary mechanism to be limited and furthermore limits the energy to be dissipated in the end of opening travel stops.
According to a preferred embodiment, the energy storage means of the auxiliary mechanism each comprise a spring arranged between the case and the support. Alternatively, it would naturally be possible to make the auxiliary energy storage means act indirectly on the support, for example on an intermediate part of the kinetic transmission system linking the energy storage means of the opening mechanism to the support. However, the preferred embodiment provides the advantage of limiting the stresses on this kinematic transmission system. Advantageously the case comprises polar compartments each containing one of said poles, the spring of each energy storage means of the auxiliary mechanism of each pole being located in the corresponding polar compartment.
According to one embodiment, the spring is a compression spring arranged inside a cylinder closed by a piston head designed to come into contact with the support and to transmit the force of the compression spring thereto. Alternatively, other types of springs can be envisaged, for example torsion or flexion springs.
BRIEF DESCRIPTION OF THE DRAWINGS
Other advantages. and features of the invention will become more clearly apparent from the following description of an embodiment of the invention, given as a non-restrictive example only and represented in the accompanying drawings in which:
FIG. 1
represents a cross-sectional view of a circuit breaker according to the invention, in the closed non-repelled position;
FIG. 2
represents in cross-section the circuit breaker of
FIG. 1
, in the closed, partially repelled position, when a dead point is passed;
FIG. 3
represents in cross-section the circuit breaker of
FIG. 1
, in the closed, repelled position;
FIG. 4
represents in cross-section the circuit breaker of
FIG. 1
, in an intermediate rocking position;
FIG. 5
represents in cross-section the circuit breaker of
FIG. 1
, in the open position; and
FIG. 6
represents in a cross-sectional plane parallel to that of
FIG. 1
, a latching mechanism in a position corresponding to the closed repelled position of FIG.
3
.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference to
FIGS. 1
to
5
, a multipole low-voltage limiting circuit breaker of high rating
10
comprises a case
12
divided into a front compartment
14
and a rear compartment
16
by an intermediate partitioning wall
18
. A window
20
made in the intermediate partitioning wall enables communication between the front and rear compartments.
The front compartment
14
acts as housing for an operating device
22
which comprises an energy storage closing mechanism
24
and an opening mechanism
26
. This device is known as such and reference should be made to the document FR-A-2,589,626 for further details thereon. It will merely be recalled here that the opening mechanism
26
comprises a toggle device comprising two rods
28
,
30
articulated on one another by a pivoting spindle
32
, the bottom transmission rod
30
being coupled to a crank
34
of a switching bar
36
. An opening spring
38
is secured between the crank
34
and a fixed securing pin
40
.
The rear compartment
16
acts as housing for the switching bar
36
and for a plurality of poles
42
arranged side by side along a pivoting axis
44
of the switching bar
36
in individual compartments separated by tight partitions appreciably parallel to the plane of
FIGS. 1
to
5
. Each pole
42
comprises a stationary contact part
46
connected to a connection strip
48
, a movable contact part
50
connected to a connection strip
52
and an arc extinguishing chamber
54
equipped with metallic separators
56
. The movable contact part
50
comprises a movable support
58
mounted pivoting around a fixed geometric axis
60
with respect to the case, and a contact finger
62
pivoting around a geometric axis
64
fixed with respect to the case and eccentric with respect to the axis
60
. A connecting rod
66
couples the support
58
to the switching bar
36
. One end of the finger
62
supports a contact pad
68
designed to perform contact with a contact pad
70
supported by the stationary contact part
46
. The other end of the finger
62
forms a cam
72
with two ramps
74
,
76
on each side of a top dead point
78
. Between the support
58
and the finger
62
there is arranged a flexible energy storage means comprising a spring
82
guided in a cage
84
and repelling therefrom a rod
86
supporting a rotating roller
88
. The roller
88
is thus permanently in contact with the cam
72
. The flexible energy storage means forms a bistable mechanism
80
with the cam
72
.
Between the case
12
and support
58
there is arranged an auxiliary flexible energy storage means
90
, able to be seen in its relaxed state in
FIG. 5
, and comprising a compression spring
92
tending to repel in the direction of the support
58
a head
94
guided in translation in a cylinder
96
fixed with respect to the case
12
. The front part of the head
94
comprises a pad
98
designed to cooperate radially with the cylinder to perform guiding and axially with a flange
100
partially closing the cylinder and forming an end-of-travel stop.
A latching device
102
, able to be seen in detail in
FIG. 6
, comprises an arm
104
pivoting around a fixed spindle
106
and flexibly urged in the clockwise direction in the figure by a torsion spring
108
. A movable stop
110
is situated at the end of the arm
104
and cooperates with a stepped surface
112
of the finger
62
. The arm has in addition a spigot
114
designed to cooperate with a cam
116
situated on the support
58
.
The intermediate wall
18
supports an end-of-travel stop
118
made of elastomer material.
Operation of the device is as follows:
In the closed position of
FIG. 1
, the contact pads
68
,
70
are in contact with one another and perform closing of the electrical circuit between the connection strips
48
,
52
. The spring
82
of the bistable mechanism
80
is compressed and the roller
88
cooperates with the ramp
74
so as to provide a contact pressure between the pads
68
,
70
. In the presence of a current surge, the electromagnetic forces tend to make the finger
62
pivot around its axis in the clockwise direction in the figures, and the bistable mechanism
80
tends to oppose this pivoting. When the current intensity exceeds a limiting threshold corresponding to the calibration of the spring
82
, the finger
62
pivots and passes the dead point
78
of the bistable mechanism
80
, represented in FIG.
2
. Once this dead point has been passed, the roller
88
cooperates with the ramp
76
and contributes to repelling the finger
62
towards the end-of-travel stop
118
, to the position of FIG.
3
. The stop
118
acts as a damper and, by absorbing the excess kinetic energy, prevents the finger
62
from rebounding. The stop
110
of the latching device
102
pivots urged by its return spring
108
and remains in contact with the stepped surface
112
of the finger
62
, so that the latching mechanism
102
prevents the finger
62
from returning to the down position.
To be able to reclose the circuit breaker, an opening operation has to be performed previously by the operating mechanism. An opening latch, actuated by an operator or a trip device, releases the connecting rod system
28
,
30
,
32
. The opening spring
38
, assisted by the springs
92
of the auxiliary energy storage means
90
of each pole, moves the switching bar
36
in counterclockwise rotation and, by means of the connecting rod
66
, makes the support
58
pivot clockwise around its axis
60
from the position of
FIG. 3
to the position of
FIG. 4
then continues on its own to urge the bar
36
until the position of
FIG. 5
is reached.
Between the position of FIG.
3
and that of
FIG. 4
, the roller
88
cooperates with the ramp
76
and applies on the finger
62
a force whose moment tends to make the finger
62
rotate clockwise around the axis
64
. The damper.
118
then acts as an end-of-travel stop so that the finger
62
remains immobile; it is therefore the roller
88
that is retracted by compressing the spring
82
. In this phase, the auxiliary energy storage means
80
of each pole repels the corresponding support
58
. The head
94
of the auxiliary energy storage means
80
reaches its end-of-travel position when the support
58
reaches the intermediate rocking position of
FIG. 4
, so that contact between the head of the auxiliary energy storage means and the support ceases.
Beyond this intermediate rocking position, the roller
88
solicits the ramp
74
. The counterclockwise movement of the finger
62
is however counteracted by the stop
110
of the latching means
102
, so that the finger
62
remains relatively immobile, with exception made for its assembly clearance. The action of the opening spring
38
and that of the spring
82
of the bistable mechanism are combined and move the support
58
clockwise to its up position of FIG.
5
. In an intermediate position between the position of FIG.
4
and that of
FIG. 5
, very close to the latter position, the cam
116
of the support
58
repels the spigot
114
of the arm
104
so that the latter pivots counterclockwise and releases the stop
110
. However, this releasing does not lead to any notable counterclockwise pivoting of the finger
62
, as the movement of the support
58
is then practically completed.
From the position of
FIG. 6
, closing can be triggered by action on a closing latch which releases a closing spring, making the switching bar pivot from its position of
FIG. 6
to its closed position of FIG.
1
. The bar
36
drives the support
58
counterclockwise and the finger
62
, urged only by the roller
88
which follows the movement of the support
58
, is also driven. The support
58
compresses and reloads the spring
92
of the auxiliary energy storage means
90
at the end of closing travel. This accessorily enables the impact at the end of closing travel to be limited.
For simplification purposes, the invention has been described considering each pole to comprise a single contact finger
62
, a single bistable mechanism
80
and a single auxiliary energy storage means
90
. In practice, it may be advantageous to provide a plurality of fingers per pole, for example three or five identical fingers pivoting around a common axis
64
. Each finger must then be biased by a bistable mechanism, which may be common to several fingers or independent for each finger, so that each finger is biased by a different spring. A single support
58
is however still provided for each pole. According to the size of the support
58
, in particular its width in a direction perpendicular to the plane of the figures, it may be advantageous to provide an auxiliary energy storage means
90
comprising several springs arranged in parallel. In practice, three springs arranged in parallel and each acting on a different head enable interesting dimensional characteristics to be obtained.
In practice, it is advantageous to dimension the auxiliary energy storage means in such a way that when relaxation thereof takes place they together release a greater energy than that required to compress the spring of the bistable mechanism.
The invention is naturally not limited to the embodiment described above. Various modifications are possible within the scope of the invention.
In the foregoing example, the latching mechanism
102
performs two functions: it acts on the one hand as a debounce device in the sense that, in the event of a short-circuit of very high intensity generating large electrodynamic forces, it prevents the finger, which has reached the position of FIG.
3
and comes and strikes the damper
118
violently, from rebounding and closing the contact; moreover it prevents pivoting of the finger
62
on opening when the support
58
has just passed the intermediate rocking position. However, depending on the circuit breaker rating and the dimensioning of the mechanical parts, it can be envisaged to eliminate this latching mechanism. The debounce function is then performed exclusively by the bistable mechanism
80
, which may be assisted by the end-of-travel damper
118
. The movement beyond the intermediate rocking position can for its part be limited in amplitude so as to become imperceptible, if the speed of the support
58
when passing the rocking position is sufficient.
In the described embodiment, the stop
118
performs two functions: it acts firstly as a debounce device since it absorbs a part of the kinetic energy at the end of travel of the finger
62
to its repelled position; it moreover enables the finger
62
to be immobilized when the support
58
pivots from its closed position to its intermediate rocking position. According to an alternative embodiment, these two functions can be performed by different parts. An end of repulsion travel stop of the finger can for example be arranged on the support
58
and an independent stop be arranged on the case. This arrangement enables the support
58
and the repelled finger
62
to be raised together in a first part of the travel of the support
58
to its open position before the finger
62
encounters the case stop and is immobilized with respect to the latter.
The invention has been described with reference to a limiting circuit breaker whose fingers pivot around a geometric axis
64
fixed with respect to the case. It is however also applicable to a limiting circuit breaker as for example described in the document GB-A-1,564,412 whose fingers pivot around an axis fixed with respect to the support itself pivoting around an axis fixed with respect to the case and offset with respect to the latter.
The switching bar
36
and support
58
may form a single part, in which case the connecting rod
66
disappears and the operating mechanism connecting rod system
28
,
30
,
32
is directly articulated via one of its ends on the support. This configuration corresponds to the mechanism of the document GB-A-1,564,412.
The invention is also applicable regardless of the type of opening and closing mechanism of the circuit breaker.
Claims
- 1. A low-voltage limiting circuit breaker comprisinga case; an opening mechanism comprising at least one energy storage means; one or more poles each comprising: a stationary contact part fixed with respect to the case; a movable contact part comprising: a support movable relatively to the case between a closed position and an open position; at least one movable contact finger movable between a non-repelled position and a repelled position relatively to the support; at least one bistable mechanism comprising a spring arranged between the support and the finger so that it passes via a maximum potential energy when the finger and support are situated in a dead point position relatively to one another, that it tends to urge the finger to its repelled position when the finger is situated relatively to the support between its repelled position and the dead point position, and that it tends to urge the finger to its non-repelled position when the finger is situated relatively to the support between its non-repelled position and the dead point position; a stop fixed with respect to the case for entering and remaining in contact with the finger when the finger is positioned in its repelled position and the support moves from its closed position to its open position, and remains in contact with the finger until the support passes beyond an intermediate rocking position relatively to the case, corresponding to the relative dead point position with respect to the finger, a kinematic transmission link between the opening mechanism and the support configured to urge the support to its open position when the support is in its closed position; and an auxiliary mechanism comprising one or more energy storage means urging the support to its open position over all or part of the travel of the support between its closed position and the intermediate rocking position, but no longer urging the support to its open position beyond the intermediate rocking position.
- 2. The circuit breaker according to claim 1, wherein the energy storage means of the auxiliary mechanism do not act on the support when the support is located between its intermediate rocking position and its open position.
- 3. The circuit breaker according to claim 1, wherein the energy storage means of the auxiliary mechanism of each pole are such that when movement of the support of the pole involved takes place, the energy storage means release an energy greater than or equal to that necessary to move the bistable mechanism(s) of the pole involved to their maximum potential energy.
- 4. The circuit breaker according to claim 1, wherein each pole further comprises means between the finger and the case for latching the finger in the repelled position.
- 5. The circuit breaker according to claim 1, wherein the energy storage means of the auxiliary mechanism each comprise a spring arranged between the case and the support.
- 6. The circuit breaker according to claim 5, wherein the case comprises polar compartments each containing one of said poles, the spring of each energy storage means of the auxiliary mechanism of each pole being located in the corresponding polar compartment.
- 7. The circuit breaker according to claim 6, wherein the spring of each energy storage means of the auxiliary mechanism is a compression spring arranged inside a cylinder closed by a piston head designed to come into contact with the support and to transmit the force of the compression spring thereto.
Priority Claims (1)
Number |
Date |
Country |
Kind |
99 05276 |
Apr 1999 |
FR |
|
US Referenced Citations (6)
Foreign Referenced Citations (3)
Number |
Date |
Country |
0 189 887 |
Aug 1986 |
EP |
2 589 626 |
May 1987 |
FR |
1 564 412 |
Apr 1980 |
GB |