[0001] The present invention relates to a safety valve built into a fuel gas conduit of
a household electrical appliance which has a movable armature actuated by means of
an electromagnet and is kept attracted by a flame thermocouple for combustion control.
PRIOR ART
[0002] Publication EP-1063474-A and its equivalent ES-2154594-A disclose a gas safety valve
with an initial actuating electromagnet as defined in the preamble of claim 1. The
electromagnet is provided with an actuating bobbin made of thin wire and also of a
thick wire winding for holding the electromagnet. Each of these two windings requires
an output conductor to the power supply "phase" and an output conductor to the supply
"ground". The actuating bobbin is supported on a plastic moulded insulating spool
and fitted on one of the U-shaped magnetic core branches. The valve "ground" is associated
with a metal socket supporting the magnetic core. Both ground conductors connected
to the respective winding end are guided to the metal seat inside a sealing casing
of the electromagnet, which is closed against the metal seat and welded against the
latter here. The ends of each winding connected to a phase conductor issue from the
electromagnet via a central hole in the core base, since there is no space inside
the sealing casing to guide them around the core. Both "phase" and "ground" conductors
have to be sturdy or rigid for their guidance and electrical connection to the outer
connector terminals or lugs of the valve.
[0003] The thick winding wire for the thermocouple energized winding is sufficiently rigid
for its ends themselves to be the output conductors of the thermocouple winding. The
ends of the actuating bobbin thin wire have to be spliced to a respective sturdy output
conductor before being connected to the valve electrical connector. An actuating bobbin
of the safety valve is constructed by means of a very thin wire, for example of a
diameter between 0.08 and 0.1 mm, and a high number of enclosed loops or turns on
the plastic spool, for instance between 400 and 700 loops. The problem therefore has
to be solved of connecting both ends of the thin wire winding to the thick output
conductors for the connection of the respective phase and ground. In addition, the
problem arises of insulating the phase conductors of both windings from each other,
as well as the passage through the central hole in the magnetic core and the metal
seat for the electromagnet. The actuating bobbin plastic spool is very small-sized,
especially the constructional details used as means for guidance and insulation of
the output conductors, which raise a problem of configuration of the moulded piece
for its assembly on one of the core branches only without the guidance means of both
phase conductors interfering during the installation of one or other winding on each
branch of the core.
[0004] On the safety valve of the prior art mentioned above, the actuating bobbin has a
rigid output conductor to the phase guided through the core, which is inserted in
an insulating terminal post on the plastic spool, and the end of the thin wire of
the bobbin is spliced to the rigid phase conductor in a central cavity in the metal
seat.
DISCLOSURE OF THE INVENTION
[0005] The object of the present invention is a gas safety valve adapted to a household
electrical appliance whose actuating electromagnet has a winding for controlling combustion
using a thermocouple and an initial valve actuating bobbin, as defined in claim 1.
[0006] The electromagnet is constructed on a U-shaped core and the actuating bobbin and
the winding for the thermocouple are each assembled on one branch of the core. The
actuating bobbin attracts the movable electromagnet armature to avoid the manual pushing
the valve member open during the prior thermocouple heating interval. The special
construction of the electromagnet and of the output conductors "phase" and "ground"
for the actuating bobbin and the holding winding, resolve the problems raised in the
prior art, in particular the construction of both output conductors for the bobbin
supply phase and ground, around 0.4 mm and 0.6 mm thick respectively, using the ends
of the bobbin thin wire themselves, and their guidance through the valve insulated
from each other and from the metal parts of the electromagnet. The safety valve actuating
bobbin is constructed by means of a wire with a preferred thickness of 0.1 mm, and
a high number of wire turns enclosed in the plastic spool, preferably between 400
and 500 turns, to be supplied by an electrical circuit provided with a capacitor which
discharges an instant current peak of 2-3 A in the bobbin for resetting the armature.
[0007] Also resolved by the invention are the problems stemming from the lack of space in
the small sealing casing where the magnet assembly is housed, for the mounting of
the actuating bobbin and the thick wire winding for the thermocouple on either branch
of the core, and due to the lack of space also the rear electrical connections of
the four wire ends, taking them out of the core to the valve outer connector lugs
or terminals.
DESCRIPTION OF THE DRAWINGS
[0008]
FIG. 1 is a longitudinal sectional view of a gas safety valve showing an actuating
bobbin and a holding winding energized by a flame thermocouple.
FIG. 2 is a plan view of the safety valve in figure 1.
Figures 3A and 3B are views of the support spool of the actuating bobbin shown in
figures 1 and 2.
DETAILED DESCRIPTION OF THE INVENTION
[0009] In reference to figures 1 to 3, a preferred embodiment of safety valve 1 according
to the invention, comprises an electromagnet 2 with an actuating bobbin 7 and a thermocouple
winding 6 each fitted on one branch 11a, 11b of a U-shaped core 11. The movable electromagnet
armature 4a is connected to the valve member 4 and is attracted instantly to open
up the flow of gas by means of bobbin 7, supplied with a current peak of 2-3 A. The
electromagnet 2 is housed in a sealing casing 3 that closes against a metal socket
5, which is the support for the circular base 11c of the core and represents the electrical
"ground" pole of the valve.
[0010] In one example of construction, the diameter of the circular section of the electromagnet
core 11 is around 7.5 mm and the separation space between its two branches 11a, 11b
is around 1.5 mm. The actuating bobbin is constructed with 400-500 turns of wire about
0.1 mm thick, enclosed in a semicircular section spool 13 provided with two transverse
flanges 13a, 13b covering either end of the bobbin 7, about 8 mm apart from each other
in the axial direction, and fitted on one of said branches 11a of the core.
[0011] The actuating bobbin 7 has a moulded plastic insulating spool 13 (FIG. 3A and 3B)
made up of one tubular spool wall and two transverse flanges 13a, 13b enclosing the
layers of wound thin wire, about 8 mm apart from each other. The core branch 11a wherein
the bobbin 7 is fitted is semicircular section. The winding of thick wire 6, of about
0.6 mm, formed prior to its installation on the core 1, is inserted on the other branch
11b from above. The facing flat faces of both core branches 11a, 11b are spaced with
a gap between them as little as 1.5 mm. For its electrical connection to the electromagnet
2 power supply, the actuating bobbin 7, whose wire is as thin as 0.1 mm, is provided
with a phase conductor 9 and the thick wire winding 6 of around 0.6 mm is provided
with a phase conductor 8, which is itself the end of the winding wire 6. Both electromagnet
2 "phase" output conductors 9, 8 issue axially to the lugs 24 of the safety valve
outer connector. Being connected electrically to the core 1, the metal socket 5 has
a circular surface within the sealing casing 3, of which on two points 18, 18' (FI.
2) both ground conductors 16 and 17 guided laterally to the core 11 are welded separately.
[0012] The insulation and guidance means for both phase conductors 9, 8 comprise a moulded
isolator bushing 14, integral with a spool wall 13 and extending from it in the axial
direction, which passes through the central hole in the core 11. Both phase conductors
9, 8 are guided from the wound wire end next to the base of the core 11c, entering
first through the isolator bushing 14, and at the outlet from the latter by means
of an insulating filler 12 in the outer connector. Due to the small gap between the
two branches 11a, 11b of the core, the spool 13 is also constructed with a separating
lip 23 extending radially from a transverse flange 13b, for the separation of the
thick wire winding 6 fitted on the other branch 11b of the core.
[0013] Being made of thin wire the actuating bobbin 7 needs the two sturdy conductors, the
phase conductor 9 and ground conductor 16, to be taken to their respective outer electrical
connection on the valve. Both bobbin 7 output conductors 9, 16 are constructed by
means of the braiding of their respective thin wire end to the outlet of the spool
1, until reaching a thickness of 0.4 mm, so that each of them becomes sturdy enough
for their guidance and handling during the assembly of the electromagnet 2.
[0014] The isolator bushing 14 is preferably moulded in a hollow tubular shape with two
openings or insertion mouths 19, 20 which are adjacent and transverse to the axis
of the spool 13. The phase conductor 9, in the form of braiding of the thin wire end,
is passed through an insertion opening 20 in the isolator bushing 14. Likewise, the
thermocouple winding phase conductor 8 is introduced from a second insertion opening
19, after the bobbin 7 has already been fitted on the core branch 11a. Both transverse
openings 19, 20 in the isolator bushing are separated by an intermediate partition
14a for insulation between both phase conductors 9, 8. The isolator bushing 14 also
has a longitudinal opening 21 to allow for its diametric expansion, which is also
helps to facilitate the insertion of the phase conductor 9 in the isolator bushing
14, through being flexible. When both phase conductors 9, 8 are inserted, the longitudinal
opening 21 is closed with a drop of resin to prevent the phase conductor 9 from being
pulled out.
[0015] The ground conductor 16 is guided from its spool 13 outlet in the open end of the
core 11 towards the periphery away from the core 11. For this purpose the spool is
made up of at least one transverse flange 13b next to the base of the core 11c and
two notches 22 cut in the transverse flange 13b, one on either side of the tubular
bushing 14, by means of which the bobbin 7 ground conductor 16 is tensioned and guided,
with one conductor turn 16a encircling the isolator bushing 14, towards the outside
of the circular profile of the core 11 for welding up on a surface point 18 of the
metal socket 5.
1. Gas safety valve adapted for controlling combustion on an household electrical appliance,
of the type having an electromagnet (2) actuator with a U-shaped magnetic core (1)
provided with a circular base (11c), that attracts a movable armature (10) raising
the shaft and closure member (4) of the valve (1) in their axial direction so as to
open up the flow of gas, said safety valve including a metal socket (5) for the magnetic
core which forms the electrical supply "ground" connection of the electromagnet (2)
and a sealed casing enclosed by the metal socket (5) housing the electromagnet (2),
which comprises a thin wire (15) actuating bobbin (7) fitted on one of the branches
(11a) of the core, and energised by an external DC current pulse for the attraction
of the armature (4a), and a thick wire winding (6) on the second branch (11b) of the
core for holding the armature (10) attracted and supplied by a flame thermocouple,
an insulating spool (13) supporting the bobbin (7), and means for the electrical (12-14)
insulation of the two "phase" conductors (9,8) of both windings guided through a central
hole in the core base (11c) for the respective electrical connection in an outer electrical
connector (24) of the valve, characterised in that the actuating bobbin (7) being constructed with several layers of thin wire (15),
its phase output conductor (9) is formed directly at the end of the bobbin and guided
together with the phase conductor (8) of the thick wire winding (6), each of these
departing from its respective winding end (7,6) on the corresponding core branch (11a,11b)
and passing through the core (11c) insulated from each other, by means of a hollow
isolator bushing (14) extending in the axial direction, which is moulded integral
with the spool (13) and is provided with at least one opening (19-21) for the insertion
and guiding of both phase conductors (9, 8) during the assembly of the electromagnet
(2) to beyond the base (11c) of the core.
2. The gas safety valve according to claim 1, wherein said isolator guide bushing (14)
is formed with two insertion openings (19, 20), at least one of which is transverse
to the axis of the spool (13), for guiding either of the two "phase" conductors (9,
8).
3. The gas safety valve according to claim 1, wherein said isolator guide bushing (14)
is formed with two insertion openings (19, 20) transverse to the axis of the spool
(13), for guiding either of the two "phase" conductors (9,8), separated and isolated
from each other by means of an axially extending internal partition (14a).
4. The gas safety valve according to claim 1, wherein both output conductors (9,16) from
the actuating bobbin (7) are constructed by means of braiding the corresponding thin
wire end (15), wherein the "ground" conductor end (16) is welded on a surface point
(18) of the metal socket (5), being guided for this purpose by means of a turn (16a)
of the braided conductor encircling a cylindrical surface of the isolator bushing
(14).
5. The gas safety valve according to claim 1, wherein both output conductors (9, 16)
from the actuating bobbin (7) are constructed by means of braiding the corresponding
thin wire end (15), wherein the "ground" conductor end (16) is welded on a surface
(18) of the metal socket, and the spool (13) is formed with two transverse flanges
(13a, 13b) covering each end of the bobbin (7), and two notches (22) cut in a transverse
flange (13b), one on either said of the isolator bushing (14), by means of which the
bobbin ground conductor (16) is tensioned and guided away from the circular profile
of the core (1) for its welding up on a surface point (18) of said metal socket (5).
6. The gas safety valve according to claim 1, wherein the two ends of the actuating bobbin
are covered by two transverse spool flanges (13a, 13b), one of them provided with
an extending radial lip (23) for separating the thick wire winding (6) on the other
branch (11b) of the core.
7. The gas safety valve according to claim 1, wherein, the diameter of the core (1) of
the electromagnet being around 7.5 mm and the gap space between its two branches (11a,11b)
around 1.5 mm, the actuating bobbin (7) is constructed with 400 to 500 turns of wire
approximately 0.1 mm thick, enclosed in a semicircular section spool (13) fitted on
one branch (11a) of the core, and with two transverse flanges (13a, 13b) covering
each end of the bobbin (7) about 8 mm apart from each other.