Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to a tripping
device of an electric circuit breaker having a spring loaded
mechanism, with a cradle or hook, likely to be latched in
charged or reset position by a latch structure.
A tripping device of the mentioned type utilizes
latching members or rollers with displacement by bearing,
i.e. with low friction. These rollers are capable of taking
important reactions back without requiring an appreciable
force of unlatching and are in particular suitable for high
rating circuit breakers calling upon springs of important
strength. The splint inserted between two rollers trays-
mitt a bearing motion to the rollers by sliding without
any slip friction. In a previously known device of this
type the splint is positively controlled, for instance by
an electromagnet, and to reduce utmost the control force,
the entirety is disposed so that the rollers reactions are
perpendicularly exerted on the splint. Theoretically the
sliding force of the splint is then independent of the
reaction forces, which in the same time avoids any untimely
unlatching under the action of these forces. In another
previous device the rollers bear against inclined surfaces
to provide a shifting force acting on the splint in the
release direction to carry out a self-unlatching as soon
as the splint is unlocked. These known systems frequently
present failures which can be imputed to the sticking or
matting of surfaces into contact. This sticking restrains
or prevents the circuit breaker tripping with the known
disastrous consequences.
The present invention remedies these drawbacks.
According to the present invention there is
provided a tripping device for an electric circuit breaker
having a spring loaded operating mechanism with a matchable
cradle and a latch structure for latching the cradle in a
charged position, said latch structure comprising:
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- a pair of cooperating rollers, said cradle
having a bearing surface engaging one of said rollers in
the latched position,
- a fixed bearing surface whereon bears the
other roll of said pair of rollers, said bearing surfaces
having an opposed inclination for biasing said rollers to
roll towards and unlatched position for freeing the cradle,
- a splint inserted between said pair of rollers
and pivotal movable between a latched position and an
unlatched position for preventing the rolling movement of
the rollers in the latched position, said splint being
free to slide in the unlatched position to allow the rolling
movement of the rollers and being prevented to slide in the
latched position to prevent the rolling movement of the
rollers,
- a fixed stop having an edge engaging with the
edge of the splint in the latched position,
- a tripping lever acting positively on said
splint upon tripping to pivot the splint into the unlatched
position wherein the splint edge is released from the fixed
stop to allow sliding of the splint and self unlatching of
said latch structure, the pivotal movement of the splint
provoking a small movement for breaking the sticking forces
of the rollers.
Therefore, according to the present invention
the sticking of the surfaces into contact is broken by a
small release movement. The tripping lever crosswise acts
on the splint and it will appear from the below description
that the micro-displacements in the supporting zones of
the rollers, generated by this cross wise displacement of
the splint, break the sticking forces and initiate the
sliding motion of the splint.
It is advisable to avoid any untimely tripping,
in particular under the effect of impacts, and according to
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a development of the invention, the splint inserted between
the rollers is preferably biased in latching position by the hooking
force of the hook on the rollers. This self-latching in-
voles a higher unlatching force which can easily be kept
in acceptable limits.
The rollers, which can be balls or other any
revolution bodies, are advantageously mounted in a cage,
biased in latching position by a spring. As soon as the
hook is released the rollers come automatically back in
latching position, as the splint also bound by a pull-off
spring. When the circuit breaker is reset the hook tempo-
rarity pushes the rollers back to come and hook, and during
this switching operation the unloaded rollers easily slide
upon the splint and the spring.
Other advantages and technical data of the
invention will more clearly appear from the following
description, wherein reference is made to the accompanying
drawings given as examples without limitative manner, in
which:
Fig. 1 is an elevation Al and sectional view of a
rollers latch structure according to the invention, repro-
sensed in latching position;
Figs. 2 and 3 are views similar to Fig. 1, showing
the latch structure in the course and towards the end of us-
latching respectively;
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Fig. 4 is a section according to the line IV-IV on Fig 1;
Fig. 5 is a partial view on a magnified scale of Fig. 1.
On the figures, a cradle or hook 10 of a mechanism (not
shown) of an electric circuit breaker cooperates with a
rollers latch structure, indicated by the general mark 12.
The circuit breaker may be of the type with mounded casing
having a handle of manual operation and an automatic trip
on fault. Such circuit breakers are well known to the spew
cialists and for instance described in the US Patent
No. 3,155,802. They comprise a spring of energy storage
(not shown) for the contacts opening when the hook 10 is
released under the trip action.
In charged or closed position of the circuit breaker, the
nose-shaped end 14 of the hook 10 strikes against a roller
16, lower on the figures, of a pair of superposed rollers
16, 18 mounted in a maintenance cage 20. The upper roller
20 18 rests on a supporting area 22 of a fixed support 24, and
-the entirety rollers 16, 18, cage 20 is mounted in limited
sliding in the fixed support 24 parallel to the support-
in area 22. Between the rollers 16, 18 is inserted the
end of a splint 26 which extends almost parallel to the
supporting area 22 by crossing the cage 20. The opposite
end 28 of the splint 26 cooperates, in latching position,
with a stop plate 30 of the fixed support 24, preventing a
sliding of the splint 26 towards the right on the figures.
tripping lever 32, mounted in rotation on an axis 34,
hits the end 28 at the time of a tripping to raise this
latter above the edge of the stop plate 30 and to unlatch ;;
the splint 26 which can then -freely slide. I-
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The hooking force of the hook 10 is transmitted by the
35 lower roller 16, -the splint 26 and the upper roller 18 to
the fixed support 24. Referring more particularly -to fugue,
it can be seen that the supporting area 22 is slightly in- -
dined to form a corner with small angle with the surface
36 of the nose 14 and -that the hooking force of the hook
10 tends to drive the rollers 16, 18 out outside this eon-
nor towards the right on the figures. When the splint 26
is latched, any displacement by sliding of the rollers 16,
18 becomes impossible owing to the important friction
forces of the rollers upon the splint 26 hold fixed and
upon the supporting areas 22, 36. Yen the splint 26 is
unlatched, the rollers 16, 18 will be turned thereby the
splint 26 is shifted towards the right in the directions
indicated by the arrows on the figures. The rolling Eric-
lions are very low, even in presence of a high hooking
force. It is easy to choose the angle of the supporting
areas 22, 36 to have an unlatching force, derived -from the
hooking force, sufficient to move by rolling the entirety
15 rollers 16, 18, splint 26 for a self-unlatching of the
hook 10, but inadequate for a displacement by sliding. The
nose 14 slips after a predetermined displacement of the
rollers 16, 18 towards the right, and the released hook 10
rotates towards the tripping position, the cage 20 and the
support 24 showing of course a cut 38 for passing the hook
10 (fig. 4).
The splint 26, tightened between the rollers 16, 18 is
biased by this tightening force towards a position per pen-
25 dlcular to the line 12 of the rollers 16, 18 middles,
which corresponds to the latching position of the splint 26.
On fig. 5 the splint 26 tends to rotate clockwise against
the tripping lever 32 and the stop plate 30. The latching
position is a stable position avoiding any untimely trip-
ping.
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it the time of a tripping the tripping lever 32 makes the
splint 26 counterclockwise rotate on the figures to raise
the end 28 above the edge of the stop plate 30 and to us-
latch the splint 26. During this rotation the contact points B1B2 of the rollers 16, 18 and the splint 26 are
modified, which cancels the sticking forces and initiates
the self-unlatching by rolling o-f the rollers 16, 18
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towards the right. These displacements of the contact
Joints By, By are very small but sufficient to clear any
sticking risk of the hooking The tripping lever 32 must
overcome the sliding frictions of -the end 28 on the stop
5 plate 30 and the centering force laid down by the rollers
16, 18, but these forces are easily controllable and can
eventually be reduced.
A pilaf spring 40 fastened to the axis 34 and to the
10 splint 26 pulls this latter in latching position and a
spring 42 inserted between a stop 44 supported by the
splint 26 and the cave 20, biases -this latter in hooking
position.
15 The device runs in the following way :
In hooking or latching position represented on fig 1, the
hooking force of the hook 10 is taken back by the fixed
support 24 through the rollers 16, 18. Any displacement by
20 bearing of the rollers 16, 18 is prevented by the splint
26 engaged with the stop plate 300 The small inclination
of the surface 36 of the nose 14 of the hook 10 generates
a component in the sliding direction of the splint 26 to-
wards -the unlatching position which is taken back by the
25 stop plate 30. Owing to a fault the trip induces a rotation
in the trigonometric direction of the tripping lever 32
which comes and hits the end 28 of the splint 26. In a
-first stage the splint 26 rotates (fig. Andy as soon as
the end 28 slips from the stop plate 301 the splint 26 t
30 slides, in a second stage, towards the unlatching position
under the action of the above-mentioned component. During ',.
this second stage the rollers 16, 18 turn while moving to
-the tlirection of the splint 26 to release the hook 10
(fig. 3). As soon as the hook 10 is released the springs
40, 42 draw back the splint and the rollers 16, 18 in hook- :
in position (fig. 1).
: At the time of the reset the hook rotates in the opposite
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direction and as it goes by pushes back the rollers 16,18
which are unloaded towards the right, before coming and
hooking in the position represented on fig. 1.
The entirety is simple and reliable and permits a control
o-f the important hooking forces essential in high rating
circuit breakers.
