Circuit breaker

A circuit breaker having a switch mechanism consisting basically of a pivotally mounted latch which is releasably mounted on a release member and which carries a pivotally mounted contact, and of a pivotally mounted manually operable element for operating the circuit breaker. A spring is connected to the manually operable element at a position offset with respect to the pivotal axis of the element and is arranged to apply a force to the pivotable latch at a position close to the pivotal axis of the latch. A latch lever interconnects the manually operable element and the pivotable latch and is connected to the manually operable element eccentrically with respect to the pivotal axis of the latter and is connected to the pivotable latch in a manner as to form the pivotal axis of the latter. A guide is arranged to guide the movement of the latch lever caused by operation of the manually operable element, and the spring is arranged to apply a force to the pivotable latch indirectly by engaging with the pivotally mounted contact carried by the latch.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a circuit breaker which has a switch 
locking mechanism including a rotatably supported latch which is 
releasably mounted on a release member and which carries a pivotally 
mounted contact lever, and a manually operable element for operating the 
circuit breaker, which is connected with a spring at a location offset 
with respect to the pivotal axis of the element and is connected with the 
latch at a location proximate the pivotal axis thereof. 
2. Discussion of the Prior Art 
A circuit breaker of the above-mentioned type is known from U.S. Pat. No. 
2,190,517, and incorporates a switch locking mechanism having only a few 
components, particularly in the construction of a switch locking mechanism 
in the form of a so-called "switch locking cam". However, the construction 
thereof requires a pressure spring for the manual actuation of the 
pivotable contact and the manually operable element, as well as a further 
spring which opens the contact lever when the latch is released. 
In order to again switch in the known circuit breaker this latter must, 
after a trip-free release, be manually switched back into the switch-off 
position and then again into the switch-on position. The theoretically 
required springs, one for switch movement, one for contact pressure and 
one for manual resetting and relatching are consequently reduced by only 
one spring. 
The present invention is thus based on the recognition that the known 
circuit breaker can be improved so as to render it more responsive to 
present demands, by providing a circuit breaker which, through the 
utilization of a continuously operating switch locking mechanism, such as 
a switch locking cam, in essence in the absence of a quick-break switch 
mechanism, only requires a single spring. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of the invention to provide a circuit breaker 
which incorporates a switch locking mechanism or locking cam comprising a 
pivotable latch which is releasably mounted on a release member and which 
carries a pivotally mounted contact, a pivotally mounted manually operable 
element for operating the circuit breaker, and a spring connected to the 
manually operable element at a position offset with respect to the pivotal 
axis of the element and arranged to apply a force to the pivotable latch 
at a position close to the pivotal axis of the latch. A lever 
interconnects the manually operable element and the pivotable latch, with 
the lever being connected to the manually operable element eccentrically 
with respect to the pivotal axis of the latter, and being connected to 
said pivotable latch in a manner so as to form the pivotal axis of latch. 
A guide is provided for guiding the movement of the lever effected by 
operation of the manually operable element, and in which the spring is 
arranged so as to indirectly apply a force to the pivotable latch by 
engaging with the piovtally mounted contact carried by the latch. 
The spring acting between the manually operable element and the latch is 
therefore not connected directly to the latch but indirectly through 
intermediary of the pivotally mounted contact lever carried by the latch. 
A circuit breaker of this type with a continuously operating switch 
locking mechanism or "switch locking cam" provides the advantage that 
relay chatters on the contacts are extensively avoided. It is sufficient 
to have a single spring which renders possible the necessary switch 
movement and contact pressure, manual resetting and relatching. 
Advantageously, when the spring is constructed as a tension spring, it 
engages the contact lever intermediate its axis of rotation and the 
pivotal axis of the latching lever, and wherein a rigid contact element 
associated with a contact element of the contact lever is disposed on the 
side towards the latch which is remote from the manually operable element. 
Such a circuit breaker evidences a particularly simple contruction. 
The manual resetting after a trip-free release is achieved in a simple 
manner when the manually operable element forms a guide lip for the spring 
which in the trip-free release position of its imaginary centerline up to 
about a connecting line between the latching lever and the latch, on the 
one hand, and the pivotal axis of the manually operable element, on the 
other hand. 
A particularly simple construction is obtained when the manually operable 
element is constructed with a roller shape and the latch lies on a 
magnetic rail as is known per se. In this manner the construction is 
rendered even simpler.

DETAILED DESCRIPTION 
The circuit breaker of FIG. 1 includes a switch locking mechanism or 
"switch locking cam", with a pivotally mounted latch 1, a contact lever 2 
pivotally carried by the latch 1 and a manually operable element 3. The 
latch is releasably retained by a release member 4. In the illustrated 
embodiment the latter is a magnetic rail, in essence, a combined thermal 
and magnetic release mechanism, as is known, for example, from U.S. Pat. 
No. 3,081,368 or French patent specification No. 1 309 280. A latch lever 
6 interconnects the latch 1 and element 3 and forms the pivotal axis 5 of 
the latch 1; the lever being guided within a guide 7 so that there is 
produced a generally constant distance to the latching location 8 of 
mechanism 4 in which there is retained the latch 1. The latch lever 6 is 
connected eccentrically to the manually operable element 3 with respect to 
the pivotal axis 9 thereof. A spring 10, in the embodiment shows a tension 
spring, that connects with element 3 at a position offset with respect to 
the pivotal axis of the element and is adapted to apply a force to the 
pivotable latch 1 at a position close to the pivotal axis 5 of the latch. 
Thus, the spring 10 engages the latch indirectly in that it engages the 
contact lever 2 which is overlapped partially in a U-shaped manner by the 
latch 1 and which is pivotally retained by the latch at 11. 
Disposed on the contact lever 2 is a contact element 12, and arranged on an 
associated fixed contact of the circuit breaker is a contact element 13. 
Quenching plates can be disposed between the contact elements in known 
manner, which, however, are not necessary for simple switching tasks. The 
current path through the release mechanism 4, which may also be a 
conventional electromagnetic and thermal release mechanism, can extend to 
the contact lever 2 through a stranded cable of known type (not shown), 
and from there to the contact element 13 and a connecting terminal. A 
further connecting terminal can be arranged on the other side of the 
circuit breaker at the release mechanism 4. The circuit breaker can be 
snapped onto carrier rails by means of a locking device 14 in a 
conventional manner. 
When the spring 10, upon construction thereof as a tension spring, engages 
on the contact lever 2 between its axis of rotation 11 and the pivotal 
axis 5 of the latching lever 6, it is advantageous that the fixed contact 
element 13 associated with the contact element 12 of the contact lever 2 
be disposed on the side of the latch 1 remote from the manually operable 
element 3. A construction of this type is shown in FIG. 1. In the 
exemplary embodiment, the latching lever 6 is rotatably connected to the 
manually operable element 3. 
When the circuit breaker is conducted into its switch-on position, the 
switch condition of FIG. 1 moves into that shown in FIG. 2. According to a 
further feature, the manually operable element 3 forms a guide lip 16 for 
the spring 10. The guide lip is engaged by the spring, so that in the 
trip-free release position of the circuit breaker, when the manually 
operable element 3 is held in the hand, the circuit breaker will respond 
to cause release of the pivotable latch 1 by the release member 4, so that 
the imaginary center line of the spring 10 will lift, on the one hand, 
about substantially up to a line; extending from the latching lever 6 to 
the latch 1 and, on the other hand, the pivotal axis 9 of the manually 
operable element 3. The switch position of the trip-free release is 
illustrated in FIG. 3. In this switch position, the spring 10 can contact 
considerably and an unstable condition results with respect to the torque 
cause by the tensile force of the spring 10 so that the internal spring 
forces which tend to produce a linear position cause an assumption of the 
position of FIG. 1 after release of the manually operable element 1. 
In the exemplary embodiment, the manually operable element 3 is constructed 
in a roller shape as is illustrated in the Figures. For resetting from 
trip-free release according to FIG. 3 into the switch-on position, after 
the manually operable element has been released, the latter only needs to 
be brought from the switch-off position into the switch-on position. After 
trip-free release according to FIG. 3, when the manually operable element 
3 has moved towards the right in a clockwise direction, the latching lever 
6 raises the latch 1 to the latching location 8 under the pulling force of 
the spring 10. During this sequence, the position of the latching lever 6 
and the imaginary axis of the spring 10 will increasingly diverge until 
they have reached the position shown in FIG. 1. Thereby, the torque 
exerted by the spring 10 becomes increasingly greater so as to achieve an 
increasing relatching force.