Abstract:
A valve structure includes a housing having an interior chamber, a first conduit connecting the interior chamber with a cooking chamber of a cooking device and having a first discharge cross-section, a second conduit connecting the interior chamber with the outside environment and having a second discharge cross-section, and at least one valve seat within the interior chamber having at least one valve seat opening which cooperates with at least one valve disc. The at least one valve disc moves between a closed position on the valve seat opening, and an open position spaced apart from the valve seat opening by changes in pressure in the cooking chamber. The valve operates to allow bidirectional flow of fluid to relieve over pressure and underpressure conditions, and enables automatic balancing of low pressure or vacuum in the cooking chamber.

Description:
CROSS-REFERENCED APPLICATION 
     This application claims priority to U.S. Provisional Application No. 61/591,701, filed on Jan. 27, 2012, which is incorporated herein in its entirety by reference thereto. 
    
    
     BACKGROUND 
     1. Field of the Disclosure 
     The present disclosure relates to a valve arrangement of a commercial cooking device. 
     2. Discussion of the Background Art 
     A commercial cooking device comprises a cooking chamber enclosed by a door that can be opened and closed for providing access to the cooking chamber. If the door is opened during a cooking process, e.g., for loading or unloading food products, a pressure rise can occur when the door is closed as cold air streams into the cooking chamber and heats up and expands very quickly. 
     In order to balance such a pressure rise, a known valve arrangement comprises a housing that is connected to the cooking chamber via a first conduit. The interior of the housing of the valve arrangement is also connected to the atmosphere via a second conduit. A valve member that closes and opens the conduit leading to the cooking chamber is disposed in the housing. This valve member has the function of a pressure relief valve that is opened by the high pressure in the cooking chamber and opens the conduit and is closed and closes the conduit to the cooking chamber after the high pressure is relieved. 
     The valve disc of the known valve arrangement that opens and closes the conduit to the cooking chamber has a relatively small cross-sectional area and the flow resistance of the known valve arrangement is relatively high. In this state of the art valve arrangement, a valve disc is disposed in close relation to the conduit leading to the cooking device cooking chamber and is opened for allowing high pressure from the cooking chamber to escape by the influence of the high pressure in the cooking chamber which moves the valve disc away from the conduit. In a situation where there is a low pressure or near vacuum in the cooking chamber, or where fresh air must be allowed to enter the cooking chamber such as during dehumidification, the valve disc is unable to move away from the associated conduit, because low pressure, or fresh air entering from the outside, cause the valve disc to seal more tightly against the conduit leading to the cooking chamber. In this latter situation, the valve disc must be moved away from the associated conduit using a solenoid acting upon a stem affixed to the valve disc. There is no spring associated with the stem, so that movement of the valve disc is accomplished only by action of the solenoid upon the stem, or by gravity returning the valve disc to its closed location in close relation to the conduit. 
     SUMMARY 
     The present disclosure provides a valve arrangement that is able to reduce the flow resistance so that its pressure control characteristics are improved. In particular, the present disclosure overcomes the shortcomings of the state of the art. The present disclosure provides for faster release of any high pressure or over pressure in the cooking chamber, and also provides for faster balancing of pressures between the atmosphere and the cooking chamber when the cooking chamber is in a low pressure or vacuum state. In addition, the present disclosure provides for automatic balancing of such a low pressure or vacuum situation in the cooking chamber. 
     The valve arrangement according to the present disclosure makes it possible to use a larger valve disc that, in conjunction with the enlarged discharge cross-section of the valve seat opening, results in the advantage of a lower flow resistance. This, in turn, enhances the dehumidification of the cooking chamber and improves the balance of any pressure differences between the cooking chamber and the atmosphere. 
     In one particularly preferred embodiment of the present disclosure, the valve disc means of the valve arrangement comprises a vacuum valve disc as well as a pressure relief valve disc. This results in the advantage of an integration of a high-pressure and a low-pressure function that makes it possible to balance both an increased pressure as well as a vacuum or reduced pressure within the cooking chamber. This embodiment is especially advantageous because the creation of a reduced pressure within the cooking chamber by, e.g., spraying cold water into the cooking chamber for drying the chamber atmosphere, can result in the undesirable effect of sucking waste water into the cooking chamber. 
     More particularly, the valve arrangement of the present disclosure finds use in commercial cooking devices, in particular in those commercial cooking devices known as combi-steamers. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further advantageous, features and details of the present disclosure will become apparent from the following description of the drawings, in which: 
         FIG. 1  shows a simplified depiction of a commercial cooking device according to the present disclosure in a highly simplified way, 
         FIGS. 2 to 4  are highly simplified depictions of a first embodiment of a valve arrangement according to the present disclosure, 
         FIGS. 5A and 5B  are highly simplified depiction of a second embodiment of the valve arrangement according to the present disclosure, and 
         FIGS. 6 to 8  are highly simplified depictions of a third embodiment of the valve arrangement according to the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  shows commercial cooking device  12 , in particular a combi-steamer. Cooking device  12  comprises housing  13  with door  14  that can be opened and closed to expose interior of cooking device  12 , i.e., cooking chamber  15 , in order to load and unload food products into and out of cooking chamber  15 . Fan wheel  17  is located within cooking chamber  15 . Fan wheel  17  is driven by motor  16  and comprises fan blades  18  at rear side of fan wheel  17  in order to create a slight negative pressure behind fan wheel  17 . Finally, cooking device  12  comprises control means  19  that is adapted to control all the components of cooking device  12 , and valve arrangement  20 . Valve arrangement  20  is connected to cooking chamber  15  by means of first conduit  8  and to atmosphere A by means of second conduit  9 . Cooking chamber heater  21  is disposed next to fan wheel  17 . Condenser  52  is connected with cooking chamber  15  via outlet  53 . Condenser has water level  56  and drain  55  as well as air vent  54  leading from condenser  52  to atmosphere A. Drain  55  extends part way into condenser  52  to provide water level  56  inside condenser  52 . 
     Valve arrangement  20  of the embodiment shown in  FIG. 1  can be used for the purpose of active dehumidification of cooking chamber  15 . So, upon opening valve arrangement  20 , dry air can be sucked into cooking chamber  15  by means of the slight negative pressure created by fan blades  18  behind fan wheel  17 . Thus, an air/vapour mixture can be guided via outlet  53 , condenser  52  and air vent  54  to atmosphere A, providing a continuous flow of fluid between inlet  9  and outlet or air vent  54 . 
     Embodiments and details of valve arrangement  20 , including its functioning for an active dehumidification, will be described in the following paragraphs with reference to  FIGS. 2 to 8 . 
       FIGS. 2 to 4  show a first embodiment of valve arrangement  20  in different switching positions. 
     As can be seen from  FIGS. 2 to 4 , valve arrangement  20  comprises housing  7  including first conduit  8  and second conduit  9 . Conduits  8  and  9 , respectively, connect interior chamber  22  of housing  7  with cooking chamber  15  and atmosphere A. 
     Valve arrangement  20  comprises, according to the embodiment shown in  FIGS. 2 to 4 , valve seat  23  that is disposed within interior chamber  22  of housing  7 . Valve seat  23  includes valve seat opening  24  cooperating with valve disc means  25 . Valve disc means  25  is moveably mounted between a closed position in which valve disc means  25  is seated on valve seat opening  24 , as can be seen from  FIG. 2 . Moreover, valve disc means  25  can be moved to an open position in which valve disc means  25  is disposed away from valve seat opening  24  (see  FIGS. 3 and 4 ). 
     To move valve disc means  25 , actuator  3  is provided that is either fixed to housing  7  or a suitable position of cooking device  12 . In the embodiment shown in  FIGS. 2 to 4 , actuator  3  can be, e.g., a solenoid cooperating with stem  29 . 
     As can be best seen from  FIG. 3  showing a switching condition in which valve disc means  25  is separated from valve seat opening  24 , valve seat opening  24  has discharge cross-section DCS 24  that is represented by a double arrow. Discharge cross-section DCS 24  is larger than discharge cross-section DCS 8  of first conduit  8 , and discharge cross-section DCS 9  of second conduit  9 . 
     In order to provide larger discharge cross-section DCS 24  of valve seat opening  24 , valve arrangement  20  of the present disclosure comprises, according to the embodiments of  FIGS. 2 to 4 , socket  26  that extends into interior chamber  22  of housing  7 . As can be seen from  FIGS. 2 to 4 , socket  26  comprising valve seat opening  24  surrounds aperture  9 ′ of second conduit  9 , with aperture  9 ′ opening into interior chamber  22 . 
     The preferred embodiment of  FIGS. 2 to 4  includes valve disc means  25  that comprises vacuum valve disc  1  that has at least one through-hole, preferably a plurality of through-holes that, according to the depicted embodiment of  FIGS. 2 to 4 , are represented by through-holes  27  and  27 ′. 
     Moreover, valve disc means  25  also comprises pressure relief valve disc  5  that is disposed next to vacuum valve disc  1  and can be moved relative to valve disc  1 . 
     As can be seen from  FIGS. 2 to 4 , vacuum valve disc  1  has cross-sectional area CSA 1  that is larger than discharge cross-section DCS 24  of valve seat opening  24 . In turn, pressure relief valve disc  5  has cross-sectional area CSA 5  that is smaller than discharge cross-section DCS 24  of valve seat opening  24 . 
     Vacuum valve disc  1  is biased into a rest position by means of spring  2 B that surrounds first length  28  of stem  29 . First length  28  of stem  29  extends from vacuum valve disc  1  to actuator  3 , as can be seen from  FIGS. 2 to 4 . 
     In order to be able to bias vacuum valve disc  1  into the closed position, one end of spring  2 B abuts vacuum valve disc  1  and other end of spring  2 B abuts shoulder  7 A of housing  7 . 
     Pressure relief valve disc  5  is biased into a closed position by second spring  2 A that surrounds second length  30  of stem  29 , with end  31  of spring  2 A abutting pressure relief valve disc  5  and end  32  of spring  2 A abutting stop plate  33  fixed to an end  34  of the second length  30 . 
       FIGS. 2 and 3  show the closed position of pressure relief valve disc  5  blocking through-holes  27  and  27 ′. 
       FIG. 2  depicts the closed position of valve disc means  25  in which vacuum valve disc  1  is seated on valve seat  23 , thus closing valve seat opening  24 . Pressure relief valve disc  5  is pressed downwards onto vacuum valve disc  1 , thus closing and blocking through holes  27  and  27 ′. 
       FIG. 3  shows the open position of valve disc means  25  in case of a high negative pressure within cooking chamber  15 . In this situation, valve disc means  25  is displaced and lowered by means of high negative pressure within cooking chamber  15 , thus spacing vacuum valve disc  1  from valve seat  23  so that valve seat opening  24  is opened. A flow of fresh air (represented by arrows  11  in  FIG. 3 ) can flow from atmosphere A through second conduit  9  into interior chamber  22 , through first conduit  8  out of interior chamber  22  and into cooking chamber  15 , thus balancing the pressures between atmosphere A and cooking chamber  15 .  FIG. 3  also shows the position of valve disc means  25  in case of an active dehumidification for which purpose actuator  3  is operated such that valve disc means  25  is lowered in order to open valve seat opening  24  allowing fresh air into cooking chamber  15 . 
       FIG. 4  shows a high pressure situation within cooking chamber  15 . In this situation, vacuum valve disc  1  is pressed onto valve seat  23  by means of spring  2 B thus closing valve seat opening  24 . However, flow of air  10  flowing from cooking chamber  15  into interior chamber  22  of housing  7  and lifts pressure relief valve disc  5  upwards against the force of spring  2 A. Through holes  27  and  27 ′ are opened such that flow of air  10  can proceed from cooking chamber  15  through conduit  8  into interior chamber  22  through through-holes  27  and  27 ′ into second conduit  9  and to atmosphere A. 
       FIG. 5A  shows a second embodiment of valve arrangement  20 . In  FIG. 5A , all the features that correspond to the first embodiment set forth in  FIGS. 2-4  are designated with the same reference numerals. 
     As can be seen from  FIG. 5A , this embodiment of valve arrangement  20  comprises valve seats  35  and  36  that are suitably disposed within housing  7 . Each of valve seats  35  and  36  has associated valve seat opening  37  and  38 , respectively, comprising associated discharge cross-sections DCS 37  and DCS 38 , respectively. Discharge cross-sections DCS 37  and DCS 38  are larger than discharge cross-sections DCS 8  of conduit  8  and DCS 9  of conduit  9 . 
     First valve seat opening  37  cooperates with vacuum valve disc  39  that is biased by spring  41  onto valve seat  35  thus closing valve seat opening  37 . Valve seat opening  37  can be opened by high negative pressure in cooking chamber  15 . Also, this embodiment comprises actuator  40  that cooperates with stem  48  fixed to vacuum valve disc  39 . Actuator  40  can also be used for opening valve seat opening  37  for the purpose of dehumidification of cooking chamber  15 . For this purpose, valve seat opening  37  can be opened by operating actuator  40 . 
     Second valve seat  36  comprises valve seat opening  38  that cooperates with pressure relief valve disc  42 . Pressure relief valve disc  42  is moveably mounted on guide means  43  by means of stem  49  that is fixed to pressure relief valve disc  42 . Guide means  43  can be fixed to housing  7  and comprises inner bore  51  that guides stem  49 . 
     If a high pressure is created in cooking chamber  15 , pressure relief valve disc  42  will be lifted by the air flow out of cooking chamber  15  into interior chamber  22  so that valve seat opening  38  is opened and the air under high pressure can be vented via conduit  9  to atmosphere A. 
     In case of a vacuum or low pressure in cooking chamber  15 , valve disc  39  will be lowered, thus opening valve seat opening  37  so that a flow of air from atmosphere A can flow through conduit  9  into interior chamber  22  and through conduit  8  into cooking chamber  15 . 
       FIG. 5B  is similar to  FIG. 5A , except that stem  48  and spring  41  are disposed on the opposite side of valve seat  35  vacuum valve disc  39 . 
     The embodiment according to  FIGS. 6 to 8  differs from the embodiment of  FIG. 5  by the provision of rocker lever  44  that is pivotally mounted within housing  7  and cooperating with vacuum valve disc  39  and pressure relief valve disc  42 . All components and features that correspond to the embodiment of  FIG. 5  are designated with the same reference numerals so that reference can be made to the respective description of  FIG. 5 . 
     As can be seen from  FIGS. 6 to 8 , rocker lever  44  comprises first rocker arm  47  that is fixed to vacuum valve disc  39 . Rocker lever  44  comprises second arm  46  that abuts an end face  50  of pressure relief valve disc  42 . Bearing  45  is provided that pivotally supports rocker lever  44  within housing  7  to allow pivoting movement that can be seen in  FIGS. 6 and 7 . 
     Also with this embodiment, a high negative pressure within cooking chamber  15  moves vacuum valve disc  39  downwardly against the biasing force of spring  41  that results in a pivoting movement of rocker lever  44  so that rocker arm  46  lifts pressure relief disc  42  upwardly, as can be seen in  FIG. 7 . This movement opens both valve seat openings  37  and  38  so that the full cross-sectional area is open for flow of air  11  from atmosphere A to cooking chamber  15  and through interior chamber  22 . 
       FIG. 8  shows the situation of an overpressure in cooking chamber  15 . In this case, valve seat opening  37  is closed by vacuum valve disc  39  while the high pressure and flow of air  10  lifts pressure relief valve disc  42  upwardly, thus opening valve seat opening  38 . In this manner, the flow path is open from cooking chamber  15  to atmosphere via conduit  8 , internal chamber  22  and conduit  9 . 
     In the above detailed description, the specific embodiments of this disclosure have been described in connection with its preferred embodiments. However, to the extent that the above description is specific to a particular embodiment or a particular use of this disclosure, this is intended to be illustrative only and merely provides a concise description of the exemplary embodiments. Accordingly, the disclosure is not limited to the specific embodiments described above, but rather, the disclosure includes all alternatives, modifications, and equivalents falling within the true scope of the appended claims. Various modifications and variations of this disclosure will be obvious to a worker skilled in the art and it is to be understood that such modifications and variations are to be included within the purview of this application and the spirit and scope of the claims.