A steam oven

Abstract

A steam oven 100 comprising a door frame 4 and a sill 10. The oven has a door 2 comprising a bottom rail 11 and a ramp 20. In use, activating the ramp raises a proximal end of the ramp until it is level with a floor the interior space (12,fig.3) of the steam oven, thus allowing a trolley to roll into the steam oven. Upon deactivating the ramp the proximal end of the ramp is lowered to below the level of door frame thus exposing a surface of the sill of the door frame with which a sealing element 18 on the bottom rail of the door can positively interact when the door is in a closed position. The ramp may be activated and deactivated using a pneumatic or hydraulic system. A sealing element (14,fig.3) may be provided on any of the sill, a head jamb 8 and at least one of side jambs 3,6 of the door frame. A method of loading and unloading a steam oven is also claimed.

Description

The present invention relates to an improved industrial steam oven for processing bulk qualities of food items efficiently. Background to the Invention When food items such as vegetables, meat or fish are produced for sale on an industrial scale, it may be necessary to cook or precook the food items in order to produce end products such as mashed potatoes, precooked meals etc.. The advantages of steaming are well known in the food industry as benefits include a shorter cook time and reduced nutrient loss in comparison to other traditional cooking methods such as boiling or conventional dry oven cooking. Steam ovens typically contain a reservoir of water and a large inner space in which food items can be placed. When the steam oven is in operation the water reservoir is heated such that the water evaporates into steam. This can be achieved by a central boiler system, whereby steam is piped from the central boiler system to individual ovens for use. The steam is then circulated within the large inner space in order to cook the food items therein. Industrial steam ovens are the preferred option in order to steam bulk quantities of food efficiently. Industrial quantities means that for efficiency the food items are loaded onto trays and stacked in a wheeled trolley outside the steam oven and the entire trolley is then rolled into the large inner space of the steam oven and remains in place during the cooking event. Once the door of the steam oven is closed and the steam formation has begun, it is preferable that the steam stays within the large inner space. Any steam which escapes to the exterior of the oven represents a wastage in terms of energy (particularly gas, which is used to produce steam) and time and may also affect the consistency of the steaming process in terms of heat and exposure. If too much steam escapes, the food items may not be consistently cooked to the desired specifications. Summary of the Invention According to the invention there is provided a steam oven comprising a conventional steam oven structure including a doorframe comprising two side jambs, a head jamb and a sill; a door comprising a hinge stile, a lock stile, a top rail and a bottom rail; a ramp; and a means for activating and deactivating the ramp; wherein, in use, activating the ramp raises a proximal end of the ramp until it is level with a floor of an interior space of the steam oven, thus allowing a trolley to roll into the steam oven and deactivating the ramp lowers the proximal end of the ramp to below the level of door frame thus exposing a surface of the sill of the door frame which positively seals with a sealing element on the bottom rail of the door when the door is in a closed position. Preferably, the means for activating and deactivating the ramp is a pneumatic system. Alternatively, the means for activating and deactivating the ramp is a hydraulic system. Preferably, a sealing element is additionally provided on the sill of the door frame. Preferably, a sealing element is additionally provided on the head jamb of the door frame. Preferably, a sealing element is additionally on at least one side jamb of the door frame. According to the invention there is additionally provided a method of loading and unloading a steam oven comprising the steps of: Opening a door of the steam oven, Activating a ramp to raise a proximal end of the ramp to correspond to floor level of the interior space of the steam oven, Rolling at least one loading rack (or trolley) into an interior space of the steam oven, Deactivating the ramp to lower the proximal end of the ramp to below the level of the door frame thus exposing a surface of the sill of the door frame, Closing the door of the steam oven to allow sealing elements on at least the hinge stile, the lock stile, the top rail and the bottom rail to seal against the door frame. Brief Description of the drawings The present invention will now be described, by way of example, with reference to the accompanying drawings in which; Figure 1 illustrates a perspective view of a steam oven with a closed door and a deactivated ramp in accordance with the invention; Figure 2 illustrates a perspective view of a steam oven with an open door and a deactivated ramp in accordance with the invention; Figure 3 illustrates a perspective view of a steam oven with an open door and an activated ramp in accordance with the invention Figure 4a illustrates a side view of a steam oven with an open door and activated ramp according to the invention; Figure 4b illustrates a side view of a steam oven with a closed door and deactivated ramp according to the invention; Figure 5a illustrates a perspective view of a steam oven with an open door and activated ramp according to the invention; Figure 5b illustrates a perspective view of a steam oven with a closed door and deactivated ramp according to the invention; Figure 6a illustrates a partial front view of a steam oven in the open-door configuration where a pneumatic ramp is activated; Figure 6b illustrates a partial front view of a steam oven in the closed-door configuration where a pneumatic ramp not activated; Figure 7 illustrates a perspective view of a ramp component according to the invention; Figure 8 illustrates a front view of a trolley which can be rolled inside an interior space of the steam oven of invention; and Figure 9 illustrates a side view of the trolley of Figure 8. Detailed Description Referring now to Figures 1 to 9 of the accompanying drawings, there is illustrated a perspective views, side view and front views of a steam oven, generally indicated as 100, according to an embodiment of the present invention. The steam oven (100) comprises a door (2) and a door frame (4). The door frame (4) can be divided into four distinct areas (essentially a top, bottom and two sides); head jamb (8), a sill (10), a first side jamb (6) and a second side jamb (3). The door (2) can be divided into four distinct areas (essentially a top, bottom and two sides); a top rail (9), a bottom rail (11), a hinge stile (5) and a lock stile (7). As is known in the art, the steam oven (100) provides a large interior space (12). Food items can be placed within the interior space (12) and cooked by the heat of the circulating steam within the large interior space (12). Typical dimensions of an interior space (12) are provided in the following example, although it will be appreciated that the scope of the invention is not limited to this size and larger or smaller interior spaces are included in the scope of the invention. Typical external dimensions of a steam oven according to the invention are provided in the following example, although it will be appreciated that the scope of the invention is not limited to this size and larger or smaller steam ovens are included in the scope of the invention. The dimensions of the internal space (12) and the external dimensions of the steam oven (100) in the example are not necessarily linked and either a different internal space dimension or a different external steam oven dimension can be used without departing from scope of the invention. Example: Internal space: (12): 760mm x 1915mm x 3235mm External dimensions of steam oven (100): 875mm x 2359mm x 3386mm In order to prevent steam egress, the door (2) contains sealing elements (16) on each of the hinge stile (5), the lock stile (7) and the top rail (9). When the door (2) is in the closed position, the seal on the top rail (9) positively seals against the surface of the head jamb (8), the seal on the hinge stile (5) positively seals against the surface of the first side jamb (6) and the seal on the lock stile (7) positively seals against the surface of the second side jamb (3). As the prior art necessitated a flat interface between the floor of the interior space (12) and the exterior of the steam oven (100), there was previously no exposed part of the sill (10) with which a seal count interact and thus no seal was provided on the bottom rail (11). In the prior art, a flap of rubber may have been provided on the bottom rail in order to reduce the ingress of external matter into the steam oven, however, this was not a seal and it did not prevent steam from escaping from the steam oven. The provision of sealing elements (16) and prevention of egress of steam is directly correlated to the efficiency of the steam oven (100). The sealing elements (16) are typically formed of rubber. Alternatively, the seals could be formed from Pll, PTFE, silicon or any other material which would exhibit the flexible sealing qualities of these materials. The door frame (4) may additionally comprise reciprocal sealing elements (14) on the first side jamb (6), the second side jamb (3) and the head jamb (8) such that the sealing elements (16) on the hinge stile (5), on the lock stile (7) and on the top rail (9) of the door (2) interact with the sealing elements (14) on the door frame (4) to create a seal. Food items which need to be steamed are prepared outside the steam oven (100). The internal space (12) in the steam oven (100) is limited and must be used to efficiently in order to fit a maximum amount of food items into the steam oven (100) per cooking event. There are no additional preparation resources available inside the steam oven (100) such as cutting or processing equipment, sinks etc. The food items need to be prepared outside the steam oven (1000) and then placed on trays or shelves on a steam oven compatible wheelable rack or trolley. Typically, the trolley, as shown in Figures 8 and 9, may carry up to 240kg of food at one time and thus it is necessary to wheel the trolley into the steam oven (100) rather than lifting it in. The trolley is typically provided on castors. As an example, for reference purposes and without limitation as to the scope of the invention, a typically trolley may measure approximately 1790 mm x 575 mm x 745 mm overall. In order to roll the trolley into the steam oven (100), the exterior floor surface and interior floor surface of the steam oven (100) must be level with each other. There is no sealing element on the sill of traditional steam ovens as the trolley would need to pass over any such sealing element which was provided on a sill in order to enter the interior space of the steam oven. Indeed the sill did not provide a surface with which a seal could interact as the sill needed to be flush with the exterior of the steam oven in order to allow the trolley to be rolled into the interior space. A rubber flap may have been provided on the bottom rail of the door to reduce to chance of external material entering the interior space of the steam oven, however, this rubber flap drags along the ground as the door moves from open and closed or closed and open positions, thus it is easily damaged and tends to wear fast and frequency need replacement. The lack of sealing element on the sill of the door frame and the bottom rail of the door of traditional steam ovens means that a proportion of the steam which is generated to circulate within the internal space escapes between the bottom of the door and the sill, thus significantly decreasing the efficiency of the steam oven. The steam oven (100) of the present invention incorporates sealing elements (16, 18) on at least the door (2) and provides a surface for sealing interface of these sealing elements (16, 18) on the door frame (4). A ramp (20) can be activated in order to allow the trolley to pass over the sill (10). Once the trolley is inside the interior space (12), the ramp (20) can then be deactivated, in order to allow the door (2) to close within the door frame (4). Activation of the ramp (20) means that one end of the ramp (20) is raised to a level whereby that end of the ramp is flush with the floor of the internal space (12). The ramp (20) is raised over the part of the sill (10) which provides a surface for sealing interaction with the sealing element (18) which is provided on the bottom rail (11) of the door (2). Depending on the size of the trolleys and the space available in the interior space (12), multiple trolleys can be rolled into the interior space (12) for one cooking event. Deactivation of the ramp (20) means that the raised end of the ramp (20) is lowered to a level which is lower than that of the door frame (4). Lowering the ramp (20) to a level below the door frame (4) means that the surface of the sill (10), which is provided for sealing interaction with the sealing element (18) on the bottom rail (11) of the door (2), is exposed. When the door (2) is moved into the closed position against the sill (10), the sealing element (18) on the bottom rail (11) of the door (2) makes contact with surface of the sill (10) and thus the sealing element (18) is positively sealed against the sill (10) of the door frame (4). The sealing surface of the sill (10) of the door frame (4) may additionally comprise a reciprocal sealing component which interacts with the sealing element (18) of the bottom rail (11) of the door (2). Due to the heavy and robust nature of the ramp (20) and the requirement for the ramp (20) to undergo substantial loading when the loaded trolley passes over the ramp (20) -activation and deactivation of the ramp (20) is pneumatically powered. Alternatively, the ramp could be hydraulically powered without departing from the scope of the invention. The steam oven (100) of the present invention allows access to the steam oven (100) with a trolley whilst also allowing the steam oven (100) to be sealed on all four sides. The benefits of the present invention are evident in the improvement in the efficiency of the steam oven cooking process which allows the user to benefit from energy saving in terms of both cooking times and energy consumption and their associated cost implications. Additional benefits of capturing all the steam within the steam oven (100) include health and safety considerations such as space management and food safety. In the prior art, which allows steam to escape from the steam oven, a hazard may exist due to the escaped steam crating a lack of visibility in the room housing the steam oven. The steam oven (100) of the present invention does not allow steam to escape from the oven, thus ensuring that the room housing the steam oven (100) remains from steam and visibility is not impaired. In the prior art, which allows steam to escape from the steam oven, escaped steam can condense 5 on the walls and ceiling of the room which houses the steam oven. This condensation can cause the spread of bacteria through the water droplets falling onto food product or indeed through the provision of a breeding ground for mould and rust within the room. The steam oven (100) of the present invention does not allow steam to escape from the oven, thus there is no condensation on the walls, ceiling or other surfaces in the room which houses 10 the steam oven (100). It is to be understood that the invention is not limited to the specific details described herein which are given by way of example only and that various modifications and alterations are possible without departing from the scope of the invention as defined in the appended claims. 15

Claims

1. A steam oven (100) comprising a conventional steam oven structure includinga door frame (4) comprising a sill (10);a door (2) comprising a bottom rail (11);a ramp (20);and a means for activating and deactivating the ramp (20);wherein, in use, activating the ramp (20) raises a proximal end of the ramp (20) until it is level with a floor of the interior space (12) of the steam oven (100), thus allowing a trolley to roll into the steam oven (100) anddeactivating the ramp (20) lowers the proximal end of the ramp (20) to below the level of door frame (4) thus exposing a surface of the sill (10) of the door frame (4) which positively seals with a sealing element (18) on the bottom rail (11) of the door (2) when the door (2) is in a closed position.

2. The steam oven (100) of claim 1 wherein the means for activating and deactivating the ramp is a pneumatic system.

3. The steam oven (100) of claim 1 wherein the means for activating and deactivating the ramp is a hydraulic system.

4. The steam oven (100) of any preceding claim wherein a sealing element is additionally provided on the sill (10) of the door frame (4).

5. The steam oven (100) of any preceding claim wherein a sealing element is additionally provided on a head jamb (8) of the door frame (4).

6. The steam oven (100) of any preceding claim wherein a sealing element is additionally provided on at least one side jamb (6, 3) of the door frame (4).

7. A method of loading and unloading a steam oven (100) comprising the steps of:Opening a door (2) of the steam oven (100).Activating a ramp (20) to raise a proximal end of the ramp (20) to correspond to a floor level of the interior space (12) of the steam oven (100).Rolling at least one loading rack into the interior space (12) of the steam oven (100).Deactivating the ramp (20) to lower the proximal end of the ramp (20) to below the level of the door frame (4), thus exposing a surface of the sill (10) of the door frame (4).5 Closing the door (2) of the steam oven (100) to allow sealing elements (16) on atleast a hinge stile (5), lock stile (7), a top rail (9) and the bottom rail (11) of the door (2) to seal against the door frame (4).10

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