[0001] The present invention relates to an electrical terminal box, particularly suitable
for cookers and the like.
[0002] Electrical terminal boxes are generally formed with a casing or outer body, made
of electrically insulating material such as plastics or the like, within which are
housed the individual terminals which, in the most usual form of construction, are
each constituted by a contact body to which the various conductors can be connected,
usually by means of rlamping screws, the heads of which are positioned outside the
said body, possibly in protected zones, so that such screws can, if they become loosened
and unscrewed, come away from the contact body and be lost.
[0003] This fact creates certain problems in that during manufacture of the terminal box
it is necessary to tighten these screws down into the associated threaded seats, which
may be constituted by a nut or the like, and the screws themselves must then be loosened
and unscrewed upon installation of the terminal box on the electric cooker or whatever
electrical utiliser appliance the terminal box is to be fitted. This causes, in practice,
a duplication of work, that is to say a screwing up operation during manufacture,
and an unscrewing operation during installation, which influences both the production
costs of the terminal box itself and the subsequent installation costs.
[0004] Another disadvantage resides in the fact that to effect the connection of the earth
conductor it is necessary to fit a wire which is connected to the body or casing of
the electrical appliance and which is then fixed to an earth terminal of the terminal
box.
[0005] The present invention seeks to overcome the above listed disadvantages by providing
a new type of electrical terminal box suitable for cookers and the like, which will
allow the possibility of considerably simplifying the assembly operations of the terminal
box during production, whilst also allowing it to have locking screws for the wires
which cannot be lost, that is to say which cannot become detached from the terminal
box even when the screws themselves are completely unscrewed.
[0006] According to the present invention, therefore, there is provided an electrical terminal
box suitable for electric cookers and the like, comprising an outer casing in electrically
insulating material, defining a plurality of cavities housing terminals for the connection
of electrical conductors characterised in that the terminals are snap-engageable into
the said cavities and include screws for clamping electrical conductors to respective
terminals which screws are held captive in the cavities.
[0007] In a preferred embodiment of the invention the positioning of the wires upon wiring
up the terminal box can be facilitated by the structure of the box, thus reducing
the time taken to install an appliance to which the terminal box is fitted.
[0008] Likewise, embodiments of the invention can be formed which offer the advantage that
the operations required for earthing the electrical utiliser appliance to which the
box is fitted can be performed in an extremely rapid and speedy manner without having
to have recourse to the utilisation of separate electrical wires or the like.
[0009] It must be emphasised that the electrical terminal box of the present invention,
which is particularly intended for electric cookers and the like, is easily made.starting
from elements and materials which are commonly commercially available, and, moreover,
is highly competitive from a purely economic point of view.
[0010] One embodiment of the present invention will now be more particularly described,
by way of example, with reference to the accompanying drawings, in which:-
Figure 1 is a schematic perspective, partly cut away and partially exploded view of
an electrical terminal box made according to the principles of the present invention;
Figure 2 is a perspective view of a contact body of an individual terminal of the
terminal box of Figure 1;
Figure 3 is a front elevation of the terminal box of Figure 1;
Figure 4 is a plan view from below of the terminal box of Figure 1;
Figure 5 is a rear elevation of the terminal box of Figure 1;
Figure 6 is a plan view from above of the terminal box of Figure 1; and
Figure 7 is a side view of the terminal box of Figure 1.
[0011] Referring now to the drawings, the electrical terminal box shown, which is particularly
designed for electric cookers and the like, is preferably adapted to operate with
a nominal current up to 40 amps and a nominal voltage of up to 380 volts. The terminal
box has an outer casing body 2 made in electrically insulating material and having,
as shown, an elongate generally rectangular conformation with two fixing lugs 3, provided
with through holes 4, for fixing the terminal box to the metal structure of a cooker
or the like.
[0012] Within the casing body 2 there are shaped cavities 5 of which there are three in
the case of a terminal box for a single phase supply and six in the case of a terminal
box for a three-phase supply. The cavities 5 are open at the lower side of the body
2 and into the cavities 5 can be inserted electrical terminals generally indicated
with the reference numeral 6, which snap-engage into the interior of the said cavities
5.
[0013] As can be seen in Figure 2, the terminals 6 have a contact body generally indicated
7, comprising a central portion 8 with a through hole 9, at the sides of which are
provided wings 10 which join, with the interposition of a stepped section 11, to a
contact blade 12 for the connection of a connecter terminal or the like. One of the
wings 10 has a resilient outwardly projecting tongue 13, which serves for snap-engaging
with a cooperating detent on the side of each cavity 5 in such a way as to retain
the contact body 7 within the cavity 5 once the contact body has been inserted into
the lower open part of the cavity 5 itself.
[0014] The zone delimited between the lateral wing 10 and the central portion 8 is shaped
to receive a fixing nut 20 which is substantially rectangular in plan form so as to
be non rotatable, which has a threaded hole into which a screw 21 engages, which can
be introduced through the hole 9 in the central portion of the contact body 7. When
the thus assembled contact body and clamping screw is introduced into the cavity 5,
the screw head 21a is disposed in alignment with a hole 22 in such a way as to allow
access to the head 21a of the screw 21, which has a diameter greater than the hole
22 so that the screw cannot be withdrawn through the hole 22. Upon assembly, therefore,
it is not necessary to screw up the screw tightly onto the nut as was previously the
case, in the prior art terminal boxes, but it is sufficient to insert the nut between
the wings 10 and to engage the screw in the through hole 9, and then snap-engage the
contact within the cavity 5, having the certainty that it will all remain in position,
not being able to escape from the cavity 5 due to the snap-engagement of the resilient
tongue 13; moreover, nor can the screw escape in that its head has a greater diameter
than the access hole 22.
[0015] On the upper face of the body 2 there are provided apertures 33 for the introduction
of conductor wires, disposed substantially in alignment with the section 11 which
joins the wings 10 to the contact blades 12, so that it serves as an abutment stop
to limit the introduction of the electrical wires, indicated 31, which can thus be
easily and rapidly positioned within each terminal.
[0016] Moreover, the terminal 6 is provided in correspondence with the earth wire with a
projection 40 which is disposed coplanar with one of the lugs 3 in such a way that
it is directly in contact with the outer casing of the utiliser appliance to which
the terminal box is fitted, thus directly forming the earth connection, which can
be made stable by engagement of clamping screws into the holes 41 provided on the
projections 40.
[0017] The production of the terminal box described above is extremely simple and, in fact,
after having made the outer body 2, it is sufficient to snap-engage the terminals
without effecting any preliminary assembly of the component parts, in such a way as
to house the contact body, the nut and the clamping screw within the cavity having
the certainty that none of the parts can escape. Moreover, the projection 40 of the
earth contact terminal automatically disposes itself in contact with the outer casing
to put the casing of the terminal box itself in contact with the earth.
[0018] Another important aspect of the invention is, moreover, constituted by the fact that
the screws can never escape from the cavities and, therefore, they are held absolutely
captive and facilitate all the connection operations for the electrical wiring operation,
which are also facilitated by the fact that the step portions 11 serve, in practice,
as abutment stops to limit the introduction of the wires themselves, which are thus
always precisely and rapidly positioned.
[0019] There is thus made available a terminal box designed for application to electrical
cookers, which gives the possibility of significantly facilitating all the manufacturing
operations as well as the assembly operations.
[0020] In practice, the materials used, as long as they are compatible with the specific
use, as well as the shape and dimensions can be different from that described by way
of example hereinabove.
1. An electrical terminal box suitable for electric cookers and the like, comprising
an outer casing (2) in electrically insulating material, defining a plurality of cavities
(5) for housing terminals (6) for the connection of electrical conductors (31), characterised
in that the terminals (6) are snap-engageable into the said cavities (5) and include
screws (21) for clamping the electrical conductors (31) in the terminal (6), which
screws (21) are held captive in the cavities (5).
2. An electrical terminal box according to Claim 1, characterised in that the said
terminals (6) have a contact body (7) with a central portion (8) provided with a through
hole (9) and lateral wings (10) each of which has an electrical connection blade (12)
joined thereto by a step section (11) each of which lies substantially perpendicular
to the plane of the associated wing (10).
3. An electrical terminal box according to Claim 2, characterised in that the region
of the terminal body (7) delimited by the wings (10) and the central. portion (8)
is shaped to receive a locking nut which can be engaged by a screw (21) which can
be introduced through the said through hole (9) in the central portion (8).
4. An electrical terminal box according to Claim 2 or Claim 3, characterised in that
the snap-engagement of the terminals (6) into the said cavities (5) is effected by
means of a resilient tongue (13) projecting laterally from one of the wings (10) of
each terminal body (7) and engageable with a cooperating detent (14) on the side wall
of the cavity (5).
5. An electrical terminal box according to any of Claims 2,3 or 4, characterised in
that the casing (2) has respective access holes (22) which when a contact body (7)
is disposed in a cavity (5) are in alignment with a respective said through hole (9)
on the central portion (8) of the terminal body (7).
6. An electrical terminal box according to Claim 5, characterised in that the head
(21a) of the screw (21) in the through hole (9) in the terminal body (7) has a greater
diameter than the access hole (22) such that it prevents removal of the screw.
7. An electrical terminal box according to any preceding Claim, characterised in that
the upper face of the outer casing (2) has holes (30) for the introduction of wires
(31) disposed substantially in alignment with the step section (11) of a contact body
(7) in an associated cavity, the step section serving as an abutment element for limiting
the introduction of the said wires (31) into the holes (30).
8. An electrical terminal box according to one or more of the preceding Claims, characterised
in that one terminal (6) of the terminal box has a projection (40) which is disposed
coplanar with fixing lugs (3) of the outer casing (2) for fixing to the structure
of an electrical appliance.