Abstract:
Cooking appliance having an external control panel equipped with one or more regulating valves, where the rotary regulator organ is equipped with various peripheral openings for supplying a flow Q. For the supply of one or another type of gas, NG or LPG, either the control knob or a bezel disk in the external panel are interchangeable on the appliance, being chosen between two different available units, one and the other permitting two different angular position limits A2, A3 of the regulator organ or the supply of a constant flow Qmin through one or another opening with calibrated sections, respectively for NG or LP gas. An appendix in the control knob guided in a slide groove on the control panel of the appliance, or a tongue on the bezel disk stopping the rotation of the control knob, determines the travel limit A2 for the supply of Qmin of NG.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a gas tap of the tapered rotary appendix type attached to a rotary actuating shaft, being the gas tap mounted on the panel of a cooking appliance, wherein the rotary appendix is provided with a series of openings for adjusting the flow rate according to the fuel gas family supplied to the cooking appliance. 
       PRIOR ART 
       [0002]    Gas taps of the above-defined type, provided with a dome-shaped bearing bush guiding the rotation of the actuating shaft and fulfilling at the same time the function of a cover for the hollow tap body, are already known. The gas tap is mounted on the front control panel with the actuating shaft passing through an external control panel in the appliance, and the tap body resting inside the appliance connected to a fuel gas supply tube or nipple. The external free end of the actuating shaft is fitted with a rotary control knob inserted in the latter. The control knob is removable from the shaft by pulling it out. The hollow body of the tap has its own gas outlet conduit which is connected to the respective appliance burner. 
         [0003]    An example of rotary tap of the above type is disclosed in EP-0805310-A1, having its actuating shaft coupled to a frustro-conical regulating organ, which is able to rotate a given angle for the supply of a gas flow from two angular positions spaced around 120.degree. apart, corresponding respectively to a high or maximum flow “Qmax” and to a low or minimum flow “Qmin”, the latter applied to “gentle boiling”. The rotation of the shaft as far as one of the angular positions, is started from an initial valve closed “OFF” position. 
         [0004]    In this type of known valves the actuating shaft has a pin protruding in a radial direction to limit its angular travel, guided on a circular surface in the inner face of the body cover or some other part of the valve body. The total travel of the regulating organ thus limited is, for instance, 210.degree. from the OFF position. The end position corresponds to Qmin. Any of the flows Qmax, Qint—intermediate flow—and Qmin is regulated by way of a corresponding hole or groove in the regulating organ facing the outlet conduit. All the flow rates are supplied from a common inlet conduit through an inner chamber in the regulating organ which is in communication with an outlet conduit. The Qmin outlet hole has an area of calibrated section for a standard type of given fuel gas, adjusted according to the output power of the cooking appliance burner. 
         [0005]    Solutions are already known for a single tap to be mounted on cooking appliances that use two different types of gas, such as natural gas (NG) or liquefied petroleum gas (LPG). For example, in U.S. Pat. No. 5,009,393 an additional valve element in the form of a sleeve, is inserted in the inner chamber of the tapered regulating organ. The area of the opening section for the passage of gas flow towards the outlet, which corresponds to low flow or minimum flow Qmin, is adjusted by rotating this added valve sleeve which thus modifies the uncovered section area of the outlet opening. 
         [0006]    This known solution has the disadvantage that for adjusting the Qmin for the rotation of the valve sleeve, it is necessary to use a screwdriver, which has to be inserted from an opening in the actuating shaft until it reaches the valve sleeve and to transmit a precise turn. 
       DISCLOSURE OF THE INVENTION 
       [0007]    The object of the invention comprises a gas tap for a domestic cooking appliance of the type with a frustro-conical regulating organ coupled to an actuating shaft and to a rotary control knob, which is capable of supplying different required flows of gas lying between two angular limit positions, of either of the two different types of gas, N gas or LP gas, the tap having a dual means for limiting the angle of rotation of the regulating organ, and the control knob being interchangeable on the actuating shaft, which depending on the type of gas used by the appliance can or can not be provided, with a means for guiding the rotation in cooperation with a means for limiting the rotation provided on a panel on the cooking appliance. 
         [0008]    The gas valve according to the invention is capable of providing two angular positions of the regulating organ, both spaced apart from each other to supply a different minimum flow Qmin according to the type of gas, NG or standard LPG, used as the fuel for the appliance. For this purpose the regulating organ has two successive Qmin outlet holes spaced apart in the angular direction, which face up individually with the inlet hole in the tap body, being the two different angular positions established by means of a respective rotation stop. 
         [0009]    The use of a single valve for regulating the flow of two different gas families is an advantage of the gas valve invention, when mounted on a cooking appliance. During the start-up of the cooking appliance the user only has to carry out a choice for a control knob from among two available units accompanying the valve, in accordance with the type of fuel gas NG or LP appropriate for the cooking appliance. Instead of mounting to each rotary valve shaft one elected class of control knob, the user also can choose for an element of cooker panel, from among two different available units of a panel element to be mounted on the cooker. In this way, it is not necessary to use tools for adjusting the flow, nor to learn how to adjust the regulating organ as is required in the prior art valve. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a sectional view of a gas valve fitted on a panel of a cooking appliance according to a first embodiment. 
           [0011]      FIG. 2   a  is a sectional view of the valve regulating organ according to the line II-II of  FIG. 1  with no fluid flow passage being established through the regulating organ. 
           [0012]      FIG. 2   b  is a sectional view of the valve regulating organ according to the line II-II of  FIG. 1  with a first fluid flow passage established through the regulating organ. 
           [0013]      FIG. 2   c  is a sectional view of the valve regulating organ according to the line II-II of  FIG. 1  with a second fluid flow passage established through the regulating organ. 
           [0014]      FIG. 3  is a development view of the valve regulating organ of  FIG. 2 . 
           [0015]      FIG. 4  is a front view of the valve installation panel according to  FIG. 1 . 
           [0016]      FIG. 5  is a sectional view of a gas valve fitted on a panel of a cooking appliance according to a second embodiment. 
           [0017]      FIG. 6  is a perspective view of an element of the panel of cooking appliance in  FIG. 5 . 
           [0018]      FIG. 7  is a schematic diagram of a valve connected to a multi-gas burning appliance. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0019]    With reference to  FIGS. 1-4  and  7 , a first embodiment of a gas cooking appliance  1 A such as a barbecue has an external control panel  2  on which are mounted one or more rotary gas valves of an existing general type. The cooking appliance  1 A, as schematically shown in  FIG. 7 , may be of two types in respect of the type of gas supplied, natural gas (NG) or liquefied gas (LPG) from the external source—GAS IN—through a valve inlet conduit  4  in the valve body  3   a . Each one of the valves  3  mounted on the panel  2  is always of a single type, all with a same valve body  3   a  and a same frustro-conical regulating organ  6 . The inlet flow “Q” is transmitted to an internal chamber  8  in regulating organ  6  in communication with an outlet conduit  5  in the valve body  3   a . The regulating organ  6  rotates around a central axis  10  actuated by shaft  7  for the supply of the flow “Q”, which is directed towards a burner on the appliance (not shown in the drawings), being the latter specifically adapted to either N gas or LP gas. 
         [0020]    The valve body  3   a  has an elongated shape with a similarly frustro-conical central housing cavity  15 , wherein the regulating organ  6  is pushed by a spring  11  for a tight sealing. The free end of the actuating shaft  7  is installed passing through a hole  2   a  in the appliance panel  2 , and afterwards the user fits it with a control knob  9 , which is chosen from the two different units of control knob  9 , both supplied to the user with each valve unit  3 . A cover  12  protecting the housing cavity  15 , has a tubular portion  12   b  for guiding the actuating shaft  7  in rotation. 
         [0021]    The regulating organ  6  may rotate with the shaft  7  an angle “A” in either of the two directions from an initial angular “OFF” position corresponding to the valve closed condition, to an angle A larger than 180.degree. and smaller than 360.degree. The OFF position is the initial end of the rotational travel “A”, and it is established by a radial pin  13  on the shaft. The cover  12  presents a sliding surface for the radial pin  13 , extending in a rotating arc “A3” ending in a recess  12   a  in the cover, which acts as a stop for the rotation of the radial pin  13 . 
         [0022]      FIGS. 2 and 3  show an example of the rotary valve  3  used in both embodiments  1 A and  1 B of cooking appliances described here. From the angular position OFF rotating in a clockwise direction, the frustro-conical organ  6  may regulate the supply of different gas flows, a maximum flow “Qmax”, a minimum “Qmin” and an intermediate flow “Qint” between the Qmax and the Qmin, in function of the angle rotated “A”. A constant minimum flow “Qmin” of the N gas must be higher than a “Qmin” of the LP gas, when supplied to a respective burner in both cases of the same power. 
         [0023]    Depending on whether N or LP gas is supplied to the cooking appliance, the control knob  9  to be fitted on the actuating shaft  7  is distinguished by means of an appendix  14  integral with the control knob. A first class of control knob  9  to be chosen for incorporating to each valve rotary shaft before being mounted on the appliance  1 A, represented on  FIG. 1 , is adapted for the supply of N gas, being provided therefore with a protuberance or appendix  14  projecting from a knob base  9   a  facing the panel  2 . A second class of control knob  9  lacks in having the protuberance  14  (not shown in the drawings), then the choice for supplying the gas LPB is chosen in order to be mounted on a cooking appliance  1 A for supplying gas LPG. In this case, the control knob  9  can be rotated up to an angle “A3” greater than the limit position A2 for the knob unit  9  provided with the protuberance  14 . The angular limit A3 to the position of the regulating organ  6  depicted in  FIG. 3 , is imposed by said radial pin  13  stopping against said recess  12   a  in the valve cover  12 . 
         [0024]    In reference to  FIGS. 2 and 3 , the regulating organ  6  rotates to an angular position A1=90 degrees, for the supply of a maximum flow “Qmax” of either NG or LPG on both types of cooking appliance  1 . In this angular position A1, the Qmax inflow is regulated by a through hole  16  in the regulating organ, facing the inlet conduit  4 . If the regulating organ  6  is rotated further, an intermediate flow “Qint” will be supplied by way of an ensuing flow opening  17  in the form of a groove which has a decreasing area. Being substantially lower than the Qmax, the “Qint” flow is diminishing in accordance with the angle A rotated, until a through hole  18  for a “Qmin” flow is facing the inlet conduit  4  at an correspondent angular position A2=210 degrees. The diameter D1 of this hole  18  is calibrated for the supply of a Qmin of NG. 
         [0025]    On the NG type cooking appliance, the knob class provided with the appendix  14  cannot turn through an angle larger than A2. The external control panel  2  ( FIG. 4 ) has a circular groove  20  travelled by said appendix  14  of the knob  9 . Its angular extension A2=210 degrees imposes the limit of angular travel governing the regulating organ  6 , from the OFF position to the outlet of the NG Qmin flow by way of hole  18 . 
         [0026]    Once installed on the panel  2 , the knob unit  9  chosen for the supply of LPG, lacks in having said appendix  14  or any other element limiting the angle “A” of rotation. Thus, the regulating organ  6  may rotate as far as an angular position A3=270 degrees, located farther away from the initial OFF position than the prior position “A2”, until a second through hole  19  lines up with the inlet conduit  4 . The diameter D2 of hole  19  is calibrated for the supply of a predetermined LPG “Qmin” flow. 
         [0027]    It is preferred that the control knob  9  button impose a rotational end position A2 less than the end position A3 imposed by the actuating shaft  7 ,  13 , because the valve body is constructed according to the existing model with a limit A3=270.degree. of rotation of the shaft  7 , radial pin  13  already imposed. The angular values are indicated herein as an example. Similarly, the regulating valve  3  and its rotary regulating organ  6  may be constructed with through holes  16 - 19 , superimposed for the regulation of the flow “Q” to the outlet conduit  5  of the valve instead of the inlet conduit  4  as shown in  FIG. 2 . 
         [0028]    The cover  12  of the valve body is equipped with a tubular part  12   b  for guiding the actuating shaft of the valve  7  and the recess  12   a  to limit the angular stroke A3=270 degrees corresponding to the Qmin of LPG. The cover  12  can be made at a low cost using die-stamping operations. The mould for the two different classes of control knob  9 , provided with and lacking the guide means  14  can also be made inexpensively by plastic molding. 
         [0029]    The placement of the two stop means  12   a  and  20 , respectively in the valve body  3   a  and in the control or assembly panel  2  of the appliance  1 A, each one of them with a pre-determined circular extension, corresponds with the two angular travels A3 and A2. The angular space A3-A2 existing between them corresponds to the intermediate space between the two orifices of passage  18  and  19 , which are calibrated for a constant Qmin of NG and LPG, respectively. Hence, the same valve unit  3  is valid for either of the two types of gas supplied to the cooking appliance  1 A, without the need for any adjustment or change in the regulating organ  6  for the supply of another type of gas. 
         [0030]    With reference to  FIG. 5  and  FIG. 6 , a second preferred embodiment of the cooking appliance  1 B is described below, with one or more rotary valves  3  mounted on an external panel  2 ′ of the appliance. The rotary valves  3  comprising an actuating shaft  7  with a radial pin  13 , a regulator organ  6  such as the one represented in  FIG. 2  and  FIG. 3 , and a control knob  9  having a base  9   a  and a guide means or appendix  14 , are common to the first embodiment  1 A represented in  FIG. 1  described above. In this second embodiment  1 B of the cooking appliance, the external assembly panel  2 ′ is adapted as a control panel that includes a bezel disk  22  for encircling the control knob  9 , which is fixed to an opening  2   a ′ on the visible face of the external or control panel. The bezel disk  22  is of the type used in the prior art, for the purpose of embellishing having an indicator dial of said angular positions, OFF, A1, A2, A3 of the regulating organ  6 , and forms part of the panel  2 ′. The bezel disk  22  is crossed through by one end of the actuating shaft  7  of the respective valve, having a central recess  22   a  housing the base  9   a  of the knob. 
         [0031]    The bezel disk  22  is provided with a stop means  24  for the rotation of the control knob  9 . The stop means  24  protrudes toward the guide means  14  at the base  9   a  of the knob, and is constructed preferably of a tongue  24  lifted from a cut-off in the surface of the recess  22   a , as shown in  FIG. 6 . The rotation guide means  14  hits against the tongue  24  when it has rotated to the limit position “A2” ( FIG. 3 ) of the regulator organ  6  corresponding to a Qmin flow supply of natural gas NG. In the “off” position of the valve, the appendix  14  rests on a boss  23  in the central recess  22   a , thus the space apart from the boss  23  up to the tongue  24  is the angular travel A2. A second type of bezel disk  22  lacks in having the tongue  24  for the travel stop “A2” (not represented in the drawings). It is also provided to the user of the cooking appliance  1 B, to be chosen for the supply of a flow “Qmin” of LPG gas, by which the rotation limit “A” is imposed only by the radial pin  13  of the shaft  7 , until the second limit position “A3” of the regulating organ  6 , through the calibrated orifice  19  in the regulator organ  6  ( FIG. 2 ). According to the second embodiment  1 B, the user assembles, for either the supply of NG or LPG, the same type of control knob  9  equipped with an appendix  14 , but a bezel disk  22  provided with or lacking the rotation stop tongue  24  respectively. 
         [0032]    Other embodiments of the invention in addition to those  1 A and  1 B described above are also possible. Either a half of the control knob  9  units those of the class provided with a rotation guide means  14 , or a half of the panel element units  22  those of equipped with a stop means  24 , will be chosen to be assembled in an appliance  1 A or  1 B of the type for supplying the gas NG, said guide means  14  interacting with a stop means  20  or  22  on the fixed part of the cooking appliance. On the other hand, the appliance to be supplied either with the gas LPG will be equipped either with a knob unit  9  of the half lacking the rotation guide means  14 , or with a panel element unit  22  of the half lacking the stop means  24 . 
         [0033]    Likewise, another rotation guide means of the shaft  7  different than the radial pin  13  described here can be constructed for the supply position A3 of Qmin of LPG through the calibrated orifice  19 , interacting with a travel stop in the body  3   a  also different from the recess  12   a  in the cover  12  herein described. The cooking appliance  1 A, 1 B is always equipped with identical rotary valves  3  for either the supply of NG or LPG, only chosen the class of control knob  9  provided with or lacking the rotation guide means  14 , or chosen the panel element unit  22  provided with or lacking the rotation stop means  24 .