The present invention relates to a motorized control to be used preferably
for the remote actuation of low-voltage electrical switches.
As is known, motorized controls are by now widely used for the remote
control of devices designed in particular for circuit breaking or for handling of
electrical networks, such as, for example, switches, disconnectors, or isolators.
Devices of this sort, in fact, are often located in positions that are difficult
to access for the operator who has the task of handling the electrical networks
and call for the need on the part of the operator to carry out troublesome and sometimes
dangerous manoeuvres and movements for guaranteeing actuation thereof. It appears
therefore evident that the use of motorized controls which can be remotely controlled
enables a considerable reduction in the dead times involved in the manoeuvres and
movements of the operator, at the same time providing the possibility of performing,
via a single control unit, actuation of a number of devices almost at the same time.
Current motorized controls used for actuation of low-voltage electrical
switches envisage the use of an electric motor which, according to an external control
signal, enables movement of the control lever of the switch from one position, corresponding
to a circuit-opening condition, to another position, corresponding to a circuit-closing
condition, and vice versa. In order to transfer motion from the motor to the control
lever, there are currently used different solutions, which envisage, for example,
the use of connecting rod-crank systems directly actuated by the motor or else the
use of other kinematic chains, which are sometimes somewhat complex and difficult
to put together.
The above and other motorized controls of the same kind present in
any case various additional drawbacks, amongst which, for example, the ones due
to use of mechanical end-of-travel mechanisms, which are extremely delicate elements
in terms of operation and reliability; their use also leads, at the same time. to
a considerable and disadvantageous increase in production costs.
Another drawback regards the kinematic mechanisms which are necessary
for moving the control lever and which have already been referred to above. These,
in fact, require a considerable precision both in the fabrication and in the assembly
steps, and contribute, in this way, to a further increase in the overall costs.
An example of such widely used motorized controls is given in the
patent application EP 0 872 867 A2. In this case, the motorized control is obtained
through an electric motor governed by a control logic associated thereto. Following
upon turning of the motor, corresponding kinematic mechanisms for transmission of
the motion lead to the rotation of a control lever connected at one end to the actuation
knob of an electrical switch. When the motorized control, through the control logic,
is called upon to set the switch in the circuit-closing condition, then the motor
starts up and begins to rotate the control lever until the position is reached in
which a first end-of-travel of the closing mechanism goes into action. At this point,
the control logic issues a command for reversal of the direction of turning of the
motor, which, by turning in the opposite direction, disengages the control lever
until a second end-of-travel mechanism goes into action, which blocks the motor
when the position of disengagement is reached. The reverse opening operation occurs
substantially in the same way.
On the basis of these considerations, the main task of what forms
the subject of the present invention is to overcome the drawbacks mentioned above
and, in particular, to provide a motorized control which will enable a correct and
effective actuation of switches commonly used in low-voltage electrical lines.
In the framework of the above task, a first purpose of the present
invention is to provide a motorized control in which the movement of the switch
will be based upon a simple and reliable control logic.
A further purpose of the present invention is to provide a motorized
control, moving of which will be performed through a reduced number of components
which may be easily coupled together in the assembly step.
Not the least important purpose of what forms the subject of the present
invention is to provide a motorized control that will present high reliability,
relative ease of production, and competitive costs.
The above task, as well as the above and other purposes which will appear more
clearly in what follows, are achieved through a motorized control for low-voltage
The motorized control, according to the invention, is characterized in that the
control unit generates at output a first impulse signal which constitutes a command
for the servomechanism to perform a first rotation with pre-defined direction and
amplitude and generates at output also a second impulse signal which constitutes
a command for the servomechanism to perform a second pre-defined rotation. The first
and second pre-defined rotations thus set in motion the coupling lever between a
first pre-set position and a second pre-set position, and vice versa. Each of these
two pre-defined positions represents, respectively, a circuit-opening condition
and a circuit-closing condition of the switch.
- a servomechanism;
- a control unit for governing the servomechanism; and
- a coupling lever, which is associated to the said servomechanism and can be
operatively associated to a switch.
The execution of pre-defined rotations of the servomechanism, by virtue
of a control logic based upon impulse signals, represents one of the main advantages
of the invention, in so far as it enables the coupling lever to reach the pre-set
positions without the use of end-of-travel mechanisms or similar transducers applied
external to the motor.
Further characteristics and advantages of the invention will emerge
more clearly from the description of preferred, but non-exclusive, embodiments of
the motorized control according to the invention, illustrated purely by way of nonlimiting
example in the annexed plate of drawings, in which:
- Figure 1 represents a block diagram of the motorized control according to the
- Figure 2 represents an electric circuit diagram of an embodiment of the control
unit of the motorized control according to the invention;
- Figure 3a is a first perspective view of a first embodiment of a control unit
of a motorized control according to the invention;
- Figure 3b is a perspective view of constructional details corresponding to a
first embodiment represented in Figure 3a;
- Figure 3c and 3d are a cross-sectional view and a second perspective view, respectively,
of a first embodiment represented in Figure 3a;
- Figures 4a and 4b are perspective views, from different points of observation,
of a second embodiment of the motorized control according to the invention;
- Figures 4c and 4d are a perspective view and a cross-sectional view, respectively,
of an embodiment of Figures 4a and 4b.
With reference to the aforesaid figures, the motorized control 1 for
low-voltage switches, according to the invention, basically comprises a servomechanism
10, a control unit 20, and a coupling lever 30, which is, at the same time, associated
to the servomechanism 10 and to the switch to which the motorized control 1 is applied.
In particular, the coupling lever 30 can be advantageously associated to the actuation
knob of the switch to simulate in this way what occurs in a traditional manual actuation.
The motorized control, according to the invention, is characterized
in that the control unit 20 generates a first impulse signal, which constitutes
a command for the servomechanism 10 to perform a first rotation with pre-defined
direction and amplitude, and generates a second impulse signal, which constitutes
a command for the servomechanism 10 to perform a second rotation, which is also
with pre-defined direction and amplitude. In particular, according to a preferred
embodiment of the invention, the first and the second pre-defined rotations are
performed so as to have a substantially coincident amplitude and opposite directions.
Through these two rotations, the servomechanism 10 in effect sets
in motion the coupling lever 30 between a first pre-set position and a second pre-set
position, and vice versa. Since these two positions are characteristic, respectively,
of a circuit-opening condition and of a circuit-closing condition, it may be noted
how the traditional manual action will thus be perfectly simulated.
The system for movement of the coupling lever 30, i.e., the production
of pre-defined rotations such as the ones indicated, hence enables a considerable
reliability and repeatability of the operations of circuit-opening and circuit-closing
by the switch to be obtained.
With reference to Figure 1, the servomechanism 10 according to the
invention principally comprises a control unit 12 that governs an electric motor
11, which is connected to the coupling lever 30 and is dedicated precisely to obtaining
the first and the second pre-defined rotations.
In particular, the control unit 12, by encoding at input said first
impulse signal or said second impulse signal sent by the control unit 20, sends,
at output, a command to the electric motor 11 to perform the first rotation or the
The servomechanism 10 further comprises transducer means 13 designed
to supply to the control unit 12 a signal indicating the angular distance covered
by the electric motor 11. These transducer means 13, constituted for example by
a potentiometer connected to the shaft of the electric motor 11, enable the control
unit 12 to perform a proportional control of the motor itself. The control unit
12 in fact supplies to the electric motor 11 a power proportional to the angular
distance that must be covered thereby to complete said first rotation or said second
The use of the transducer means 13 also enables a proportional control
of the speed of turning of the electric motor 11. The latter, in fact, can advantageously
turn with a speed so much greater or so much smaller as greater or smaller is the
angular distance that must be covered to complete the first rotation or the second
Once again with reference to the aforementioned Figure 1, the motorized
control 1, according to the invention, further comprises disengagement means 40
designed to release the coupling lever 30 from the servomechanism 10. These disengagement
means 40 are necessary to enable the coupling lever 30 to be free to move until
completion of the first pre-defined rotation or the second pre-defined rotation
is obtained. This condition is essential, for example, to enable a possible manual
actuation of the switch or to enable the switch itself to trigger in order to carry
out its function of protection in the case of poor operation of the network.
The disengagement means, according to a preferred embodiment of the
motorized control 1, are associated to the servomechanism 10 and are activated through
a third impulse signal sent to the servomechanism 10 itself by the control unit
With reference to Figure 2, the control unit 20 comprises appropriate
means 22 for generation of the impulse signals referred to above, as, for example,
may be traditional generators of square waves. Via the use of these electronic components,
the control unit 20, according to the invention, generates impulse signals which
have one and the same frequency but a different time duration of the impulses.
The control unit 12 of the servomechanism 10 decodes the signals at
input sent by the control unit 20, recognizing precisely the different durations
of the impulses and issuing accordingly a command to the electric motor 11 for performing
the first rotation or the second rotation, or else issuing a command for activation
of the disengagement means.
Handling of the activity of the control unit 20 by the user can advantageously
be performed through the use of traditional remote-control devices, such as radio
transmitters, or else via the use of simple pushbuttons 300, electrically connected
to the unit itself, as represented schematically in Figure 1. Advantageously, the
control unit 20 can operate via a power-supply unit 24, which supplies a supply
voltage of 6 V. This voltage value enables limitation of the number and dimensions
of the energy-accumulation means 23; the latter are necessary in order to provide
the energy necessary for the completion of the rotations referred above in the case
of sudden absence of the main power supply. Said task must be pursued ensuring normal
modes of operation, i.e., guaranteeing, for example, the same speed of rotation
of the coupling lever 30 that usually characterizes normal operation of the motorized
control 1. This aspect appears particularly important for preventing onset of dangerous
electric arcs between the contacts of the switch, for example in the case of low
speeds of rotation of the coupling lever 30, i.e., of the actuation knob of the
Figures 3a, 3b, 3c and 3d regard a first preferred embodiment of the
motorized control 1 according to the invention, which envisages a movement of the
coupling lever 30 through a rotation about an axis substantially parallel to the
axis of rotation of the servomechanism 10.
With reference to Figures 3a and 3b, the motorized control 1 comprises
a first supporting structure 50 for housing the servomechanism 10 and possibly the
control unit 20. The supporting structure 50 comprises a resting base 51, a first
surface 52, and a second surface 53. The first surface 52 develops in a direction
substantially orthogonal to the resting base 51, whilst the second surface 53 develops
in a direction orthogonal to the first surface, projecting in a raised and opposite
position to the resting base 51.
Again with reference to the aforementioned Figures 3a and 3b, the
resting base 51 and the second surface 53 comprise first means 55 for the anchorage
of the servomechanism to said first supporting structure, as, for example, may be
ordinary screw connections. The resting base 51 further comprises second anchoring
means 56 designed to enable connection of the motorized control 1 to a possible
outer containment casing 200.
Figure 3b shows the disengagement means 40 used in this first possible
embodiment of the motorized control 1. In particular, they comprise a toothed flange
41 fixed to the shaft of the servomechanism 10 and positioned at one end part of
With reference to Figure 3c, according to the invention, rotation
of the coupling lever 30 is performed through the use of a first turning pair and
of a second turning pair. In particular, said first turning pair comprises a first
bushing 70, which is inserted in a first seat 72 obtained on said first surface
52; the bushing 70 is geometrically conjugated to a pin 73 obtained on a first end
75 of the coupling lever 30. The second turning pair comprises, instead, a second
bushing 80, geometrically conjugated to a second seat 81 obtained on a second end
85 of the coupling lever 30. The second bushing 80 is fitted on the toothed flange
41. An alternative to the latter solution envisages a possible fitting of the second
bushing 80 on the servomechanism 10.
The use of two turning pairs hence renders independent the movement
of the coupling lever 30 with respect to that of the servomechanism 10. Furthermore,
this constructional solution enables advantageous increase in the twisting resistance
of the lever itself, thus enabling increase in the reliability of the motorized
With reference to Figure 3d, there is now described in greater detail
the principle of movement of the coupling lever 30 of the motorized control 1. The
control unit 20, by generating, for example, the first impulse signal, sends a command
to the servomechanism 10 to perform a first pre-defined rotation, which is considered,
purely by way of illustration, counterclockwise. The servomechanism 10 hence turns
in a counterclockwise direction, thus leading to the rotation of the toothed flange
41 fixed thereto. Said toothed flange 41, through one of its projections 42, leads
to the rotation of the coupling lever 30, which turns in a counterclockwise direction
about the axis of rotation provided by the first turning pair and the second turning
pair. Upon completion of the rotation, if the control unit 20 continues to generate
the first impulse signal, then the toothed flange 41 maintains the position reached,
preventing any movement of the coupling lever 30. This occurs in so far as upon
persistence of the first impulse signal at input, the control unit 12 for driving
the servomechanism 10 sends a command to the electric motor 11 for absorption of
an amount of electric power such as to counter any external action exerted on the
coupling lever 30, an action which, in effect, in these conditions would tend to
modify the position of the shaft of the motor itself.
If, instead, upon completion of the first rotation, which is considered
counterclockwise, the aforementioned third impulse signal is generated by the control
unit 20, then the control unit 12 sends a command to the electric motor 11 for a
rotation of the shaft in a clockwise direction, which is hence such as to disengage
the toothed flange 41 from the coupling lever 30, bringing it, in effect, into a
position which can be defined as neutral. In this way, the coupling lever is able
to move freely since it is not being blocked in any way by the toothed flange 41.
Figures 4a, 4b, 4c and 4d correspond to a second preferred embodiment
of the motorized control 1 according to the invention, which envisages, in this
case, a movement of the coupling lever 30 via a rotation about an axis substantially
orthogonal to the axis of rotation of the servomechanism 10.
In this second embodiment, the motorized control 1 comprises a second
supporting structure 90 dedicated, also in this case, to housing the servomechanism
10 and possibly the control unit 20. This second containment structure comprises
at least one third, bottom, surface 91, one fourth, side, surface 92, substantially
orthogonal to said third surface 91, and one fifth, side, surface 93, substantially
orthogonal to said third, bottom, surface 91 and opposite to said fourth, side,
Advantageously, the supporting structure can be completed through
a sixth, front, surface 94, a seventh, rear, surface 95 and an eighth, top, surface
96 so as to create a complete containment box of a substantially prismatic shape,
as appears clearly from Figures 4a and 4b.
The bottom surface 91 may moreover advantageously comprise also third
anchoring means 97 for fixing of the motorized control 1 in the proximity of the
corresponding switch to be actuated.
In this second embodiment, the motorized control 1 comprises appropriate
transmission means dedicated to transferring motion from the servomechanism 10 to
the coupling lever 30. With reference to Figures 4c and 4d, these transmission means
comprise basically a first gear 100 and a second gear 101, which are associated,
respectively, to the shaft of the servomechanism 10 and to a second shaft 105 substantially
orthogonal to the axis of rotation of said servomechanism 10. Advantageously, the
second gear and the second rotation shaft 105 can be made in a single piece in order
to decrease the number of components and thus favour the assembly operations.
Again with reference to Figure 4d, the motorized control 1 according
to the invention comprises a third turning pair and a fourth turning pair, which
are designed to enable rotation of the second gear 101 referred to above. In particular,
said third turning pair advantageously comprises a third seat 110 obtained on said
fourth, side, surface 92 and geometrically conjugated to a third end of said second
shaft 105; likewise, the fourth turning pair, instead, comprises a fourth seat obtained
on the aforesaid fifth, side, surface 93 and geometrically conjugated to a fourth
end 113 of said second shaft 105.
From Figure 4d, it may moreover be noted how the rotation of the coupling
lever 30 occurs advantageously about an axis of rotation which coincides precisely
with the axis of rotation of the aforesaid second shaft 105. This solution enables
a reduction in the number of components used and envisages the use of a fifth turning
pair and a sixth turning pair. In particular, these latter turning pairs are obtained,
respectively, through a fifth seat and a sixth seat, which are made, respectively,
on a fifth end 130 and a sixth end 135 of the coupling lever 30 and which can be
geometrically coupled with said second shaft 105.
In order to favour mutual positioning of the ends of the coupling
lever 30 with respect to the gear, the invention envisages the possibility of using
spacer means 150 fitted on the second shaft 105, which advantageously increase also
the flexural stiffness of said shaft.
In this second embodiment, the disengagement means may comprise the
aforesaid toothed flange 41, which is advantageously fixedly connected to the second
shaft 105 so as to perform its function according to modalities similar to the ones
This second embodiment proves particularly advantageous on account
of the smaller spatial encumbrance which accompanies the solution. The servomechanism
10 has, in fact, a shaft 250 of the electric motor 11 that is substantially vertical
and no longer horizontal as the one illustrated, for example, in Figure 3b and corresponding
to the first embodiment referred to above.
It must moreover be emphasized how the pair of gears thus far described
can effectively provide a reduction ratio for the purpose of obtaining a greater
twisting moment on the coupling lever and hence enabling a greater force of movement
of the lever.
The technical solutions adopted for the motorized control enable the
pre-set tasks and purposes to be fully achieved. In particular, the system of movement
of the coupling lever proves reliable and is obtained with a reduced number of components
such as to enable a reduction in the final costs and such as to facilitate the assembly
The motorized control thus conceived may undergo numerous modifications
and variations, all of which fall within the scope of the inventive idea; furthermore,
all the items may be replaced by other technically equivalent ones.
In practice, the materials used, as well as the dimensions and the
corresponding shapes, may be any whatsoever according to the requirements and the
state of the art.