Patent Publication Number: US-10788217-B2

Title: Lighting control switch harness for gas taps with optical indication of opening of the gas tap, for cooking appliances

Description:
RELATED APPLICATIONS 
     The present application is a national phase of PCT/US2010/061216, filed Dec. 20, 2010 and is based on, and claims priority from, Italian Application Number TO2009A001012, filed Dec. 21, 2009. 
     TECHNICAL FIELD 
     The present invention relates to a control switch harness for the lighting of burners of a cooking range, couplable in use to the gas taps feeding the burners and provided with an optical light indication when the gas tap is open. 
     BACKGROUND ART 
     It is known that control devices for the burners of a cooking range (either of the fitted type, or of the type belonging to a combined household appliance, e.g. comprising one or more oven cavities and/or a dishwasher) may comprise, for each burner, a gas tap and a switch harness element provided with a microswitch, the actuation of which supplies voltage to a service lighter circuit of the cooking range, of known type, which produces a sequence of sparks at one or all burners. 
     Generally, the gas tap is provided with an axially moveable, rotary control shaft or stem, provided in use with a control knob, the rotation of which allows the dispensing of combustible gas to the burner. 
     In the device known from EP1194720B1, the axial movement of the stem/knob assembly is used to actuate the microswitch, thus producing the generation of the lighting spark at the same time of the gas delivery. 
     If an optical indication of the gas tap opening is required, a supplementary device must be provided, e.g. equipped with LED, to be coupled to a gas tap. 
     Electricity is supplied to each module by means of appropriate wiring. This makes the wiring very complex and costly and weighs on assembly operations and time. 
     DISCLOSURE OF INVENTION 
     It is an object of the present invention to overcome such drawbacks by providing a lighting control switch harness for burners of a cooking range couplable to the burner feeding gas taps and provided with an optical light indication that gas tap is open, the construction and wiring of which is simple and reliable, and which is compact and relatively cost-effective. 
     The present invention thus relates to a lighting control switch harness for the burners of a cooking range, as disclosed in claim  1 . 
     In particular, the lighting control switch harness of the invention comprises a plurality of elements connected to one another and each comprising a body couplable in use to a respective gas tap and closed by a cover at least partially pervious to light and a printed circuit underneath the cover and carrying one or more light sources, e.g. LEDs. 
     According to a feature of the invention, each switch harness element further comprises a first switch accommodated within the body and comprising at least one fixed contact connected to the printed circuit, a mobile contact and first means carried by the body so as to be operatively couplable in use to a mobile stem of the gas tap for integrally rotating therewith and consequently taking the mobile contact towards the at least one fixed contact; and a second switch accommodated within the body and comprising a fixed contact, a mobile contact and second means carried by the body so as to be in use operatively couplable to the mobile stem of the gas tap for translating parallelly thereto and consequently taking the mobile contact towards the fixed contact. 
     The elements of the switch harness are mechanically and electrically connected to one another only by means of three wires passing through the body of the various elements, a first wire being connected to a first contact of the second switch of each element, a second wire being connected to the mobile contact of the first switch of each element, and a third wire being connected to a second contact of the second switch of each element, while the printed circuit of each element is further electrically connected to the first wire. 
     In this manner, by using only three connection wires, two microswitches acting on two different circuits can be incorporated in a single switch harness element, one on the service lighting circuit of the cooking range and the other on the feeding circuit of the light sources, which provide the desired optical indication that the gas tap is open, which is obtained on the printed circuit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features and advantages of the present invention will be apparent from the following description of a preferred embodiment, exclusively provided by way of non-limitative example, with reference to the accompanying drawings, in which: 
         FIG. 1  shows a three-quarters, axonometric view of an element of the switch harness according to the invention fitted on a gas tap, underneath thereto; 
         FIG. 2  shows a simple wiring diagram of the lighting harness element in  FIG. 1 ; 
         FIG. 3  diagrammatically shows the lighting harness according to the invention, and 
         FIGS. 4, 5 and 6  show the lighting harness element in  FIG. 1  with parts gradually removed. 
     
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     With reference to figures from  1  to  6 , numeral  1  indicates a lighting control switch harness ( FIG. 3 ) for the gas taps of burners  2  (of which only one is shown in  FIG. 2 ) of a cooking range (known and not shown for the sake of simplicity). 
     The switch harness  1  comprises a plurality of elements  3  connected to one another mechanically in series and electrically in parallel, according to a feature of the invention, by only three electric conductor wires, indicated by numerals  4 ,  5  and  6 , respectively. 
     Each element  3  comprises a body  10 , couplable in use to a respective gas tap  11  and closed by a cover  12  ( FIG. 1 ) at least partially pervious to light, e.g. because it is provided with at least one window  13 , ring-shaped in the non-limitative example. 
     A printed circuit  14 , carrying a plurality of LEDs  15  arranged in a circle at the ring-shaped window  13 , about the gas tap  11 , is arranged in the body  10  immediately under the cover  12 ; it is apparent that any other position of the LEDs  15  or of other light sources according to a different shape and position of the window  13  is possible. 
     The body  10  is cup-shaped and delimited, on the side opposite to the cover  12 , by a bottom wall  16  ( FIGS. 4-6 ) facing the cover  12  with the interposition of the printed circuit  14 . A first switch  20  and a second switch  21  are accommodated as integral part of each element  3  in the body  10  arranged under the printed circuit  14 , between the latter and the bottom wall  16 . 
     The switch  20  comprises at least one fixed contact  22  connected to the printed circuit  14 , a mobile contact  23  and first means  24  carried by the body  10  so as to be in use operatively couplable to a mobile stem  25  (known) of the gas tap  11  for turning integrally with the same and consequently taking the mobile contact  23  towards the at least one fixed contact  22 . 
     The switch  21  comprises in turn a fixed contact  27 , a mobile contact  28  and second means  29  ( FIGS. 4  and  6 ) carried by the body  10  so as to be in use operatively couplable to the mobile stem  25  of the gas tap  11  to translate parallelly to the same and consequently take the mobile contact  28  towards the fixed contact  27 . 
     According to the invention, the elements  3  are mechanically and electrically connected to one another only by means of the three wires  4 ,  5  and  6 , passing through the body  10  of the various elements  3 . In particular, the wire  4  is connected to a first contact  28  of the switch  21  of each element  3 , in the non-limitative case in point to the mobile contact  28 , while wire  5  is connected to the mobile contact  23  of the switch  20  of each element  3 , and wire  6  is connected to the fixed contact  27  of the switch  21  of each element  3 . Furthermore, the wire  4  is also electrically connected in a permanent manner to the printed circuit  14  of each element  3  by means of a metallic contact terminal  30  ( FIG. 6 ) carried by the body  10 . 
     On the printed circuit  14  an electric power supply circuit  31  for the LEDs  15 , substantially of known type, is obtained in known manner, the electric power supply of which is controlled by the switch  20 . 
     The bottom wall  16  is provided with a hole  33  ( FIG. 5 ) designed to couple in use with the gas tap  11 , e.g. snappingly, from the side of the mobile stem  25 , so as to be thoroughly crossed in use by the mobile stem  25  itself, which further also crosses the cover  12  facing the bottom wall  16  and the interposed printed circuit  14  by virtue of the conformation of the printed circuit  14  and the presence of a second hole  34  obtained passing through the cover  12 , coaxial with the hole  33 . 
     The means  24  consist of a ring idly guided into the first hole  33  and equipped radially on the inside thereof with (known) angular fastening means  35  to the mobile stem  25  and radially on the outside thereof with an overhanging radial appendix  36  which extends into the body  10  and cooperates with the mobile contact  23 , which consists of an elastic metal blade carried by the bottom wall  16  of the body  10  arranged on edge, i.e. with the laying plane thereof perpendicular to the wall  16  and electrically connected to wire  5 . 
     The means  29  consist of a cup-shaped bush mounted coaxially with the ring  24 , with the interposition of a helical spring  37  (visible in  FIG. 5  where the bush  29  is removed), which bush  29  is thoroughly and slidingly guided into the second hole  34  and designed to be thoroughly crossed, in use, by the mobile stem  25 . 
     In particular, the bush  29  is mounted overhangingly protruding from the cover  12  ( FIG. 1 ) and is provided with a radial arm  38  ( FIG. 4, 6 ) cooperating with the mobile contact  28  and arranged angularly offset with respect to the radial appendix  36  of the ring  24 . The mobile contact  28  consists of an elastic blade overhangingly supported flat by the bottom wall  16 , i.e. with its laying plane parallel to the latter, and electrically connected to the wire  4 . 
     In the illustrated example, the fixed contact of the switch  20  consists of a pin  22  carried by the printed circuit  14  perpendicularly to the bottom wall  16  of the body and electrically connected to the printed circuit ( 14 ) itself; the latter, as previously mentioned, is further electrically connected to the wire  4  by means of the contact terminal  30 . 
     The body  10  is further internally provided with fixing means  50  for the wires  4 ,  5 ,  6 , constituted by compression cocking elements which, working in cooperation with the fixed and mobile contact terminals of the switches  20 , 21 , prevent the wires themselves from axially sliding through the body  10  of each element  3 , thus maintaining the respective position of the elements  3  along the entire extension of the switch harness  1 . 
     In use, the switch harness  1  is mounted on the cooking range of the electric household appliance, by fitting each element  3  integrally to a gas tap  11 . 
     In order to light a burner, the user must take a control knob of the tap  11  (known and illustrated by a dashed line in  FIG. 1 ), to then turn it, by holding it pressed, to a position corresponding to the required gas flow: this movement causes a translation and subsequent rotation of the stem  25 . The pressure on the knob (not shown) is also transmitted to the bush  29 , underneath it, making the switch  21  close and consequently producing in known manner the power supplying of the lighting circuit (known and not shown) of the burners  2 . At the same time, the rotation of the stem  25  produces the rotation of the ring  24  with consequent delivery towards the burner  2 , by the gas tap  11 , of a flow of gas fuel, e.g. methane, and simultaneously the closing of the switch  20 , with consequent electric power supply of the circuit  31  carried by the printed circuit  14  and simultaneous lighting of all LEDs  15 . Through the window  13  a ring-shaped lighting is thus created about the knob (not shown) of the gas tap  11 , which remains actuated also when the knob is released, if it is not returned to the closed tap position, while the switch  21 , on the other hand, opens by elastic return of the blade  28 , making the generation of sparks on the burner  2  cease. 
     When the gas tap  11  is closed by turning the knob in the other sense, the switch  20  is opened turning the light sources off, in the case in point the LEDs  15 . In this manner, when the gas is delivered to the burner  2 , the knob of the corresponding gas tap  11  is lit, warning the user that the gas is delivered into the atmosphere. 
     It is apparent that the switch harness  1  can be adapted with changes obvious for a person skilled in the art so as to let the LEDs  15  light up gradually as the stem  25  is turned instead of making them light up all at the same time. For this purpose, it would be sufficient, for example, to replace the two-contact switch  20 , with a multiple contact switch, in which the mobile contact is a brush which progressively reaches a plurality of fixed contact, appropriately connected to one another.