WO2014042586A1

WO2014042586A1 - Oven door and rack system

Info

Publication number: WO2014042586A1
Application number: PCT/SE2013/051072
Authority: WO
Inventors: Bernt TOPPAR; Magnus KRABBE; Olof ENGSTRÖM
Original assignee: Revent International Ab
Priority date: 2012-09-14
Filing date: 2013-09-13
Publication date: 2014-03-20
Also published as: EP2894992A1

Abstract

A rack oven with a door opening and a vertically movable rack attachment means for lifting a rack comprises a curved door (21) which is movable in an arc from an open position away from the door opening to a closed position in front of said door opening. The door is connected to said movable rack attachment means so that said rack attachment means (11) moves from a low position when the door is in the open position to a high position when the door is in its closed position.

Description

Oven door and rack system Field of the invention

The invention relates to a rack oven with an oven chamber, means for rotating a rack introduced into the oven chamber, means for lifting the rack and a sliding door wherein movement of the sliding door controls lifting of the rack.

Background of the Invention

Hot air baker's rack ovens are known in which the goods which are to be baked are introduced on baking sheets arranged on square or rectangular trays or pans held in a quadratic wheeled rack. The rack is intended to be introduced into the oven chamber of the oven and to remain there while the baking process takes place. The oven chamber has a rectangular or square horizontal cross-section (i.e. the cross-section when viewed from above is rectangular or square) and is dimensioned to accept a rack and allow it to be rotated. Hot air can be introduced via one or two corner vents into the oven chamber to bake the goods. The substantially straight front side of the oven is provided with a vertically-hinged door through which racks can be loaded into and unloaded from the oven. A rack supporting system, such as a frame provided with hook which can be fitted to the rack, is suspended from the centre of the oven's ceiling. The frame is usually attached to a vertical shaft which is connected to a drive system above the ceiling which can rotate the shaft and consequently rotate the rack. In order to do this it is preferable to lift the rack from the floor to reduce friction. Lifting of the rack is conventionally controlled by movement of the door. This can be achieved by a system of rods and levers connecting the door to the shaft which automatically use the swinging movement of the door from its open position to its closed position to lift the shaft and the frame from which the rack is suspended.

A new type of baker's rack oven has been developed in which the front of the oven is curved and a curved door is arrange to slide in an arc to one side of a door opening in order to allow access to the oven chamber. Such a movement means that the conventional system of lifting the rack will no longer work as the convention system requires the door to swing about a vertical hinge in order to work. Brief Description of the Invention

The invention has for its object to provide a rack oven with a sliding door in which movement of the door from its open position to its closed position automatically causes a rack supporting system to move upwards.

This is achieved by a rack oven having the features of the characterizing part of the main claim. Advantageous embodiments are described in the dependent claims.

Thus, the present invention relates to a rack oven with a door opening and a vertically movable rack attachment means for lifting a rack arranged in an oven chamber of the rack oven. The rack oven is provided with an essentially circular horizontal cross-section. This relates both to the oven chamber and to the external of the oven. The rack oven comprises a curved sliding door which is movable along the outside of the oven in an arc from an open position away from the door opening to a closed position in front of said door opening. It is very advantageous to use a sliding door in that the required space for the oven is reduced, which in turn results in that the risk of being burned by the hot door when it is opened is drastically reduced in comparison to open a conventional hinged oven door.

Furthermore, the oven comprises a rack lifting system arranged on the roof of the oven wherein the rack lifting system is attached to the curved door and adapted to control said movable rack attachment means so that said rack attachment means moves from a low position when the door is in the open position to a high position when the door is in its closed position.

Brief Description of the Drawing

Figure 1 shows schematically an oven chamber and rack lifting system in accordance with a first embodiment of the invention with the rack in the raised position,

Figure 2 shows schematically a view from above of the oven chamber and rack lifting system of figure 1,

Figure 3 shows schematically the oven chamber and rack lifting system of figure 1 with the rack in the lowered position, Figure 4 shows schematically a view from above of the oven chamber and rack lifting system of figure 3,

Figure 5 shows an embodiment of a cam system for lifting the rack in accordance with the present invention,

Figure 6 shows an embodiment of a rotating plate for use with the cam system of figure 5,

Figure 7 shows schematically in perspective an embodiment of a means for locking and tilting an oven door,

Figure 8 shows a side view of an oven with the embodiment of a means for locking and tilting an oven door of figure 7 with the door in the closed position, Figure 9 shows a side view of the oven with the embodiment of a means for locking and tilting an oven door of figure 7 with the door in the open position,

Detailed Description of the Invention In order to illuminate the invention clearly, features of the oven relating to its heating system, rotating of the rack and its housing are omitted in the figures and the following description. Figures 1-4 shows an oven chamber 1 and rack lifting system 3 in accordance with a first embodiment of the invention. For the sake of simplicity of illustration the oven chamber is show as being cylindrical but it may have other shapes.

Rack lifting system 3 is mounted on the roof 5 of the oven chamber and comprises a rotatable vertical shaft 7 which extends from a mounting system 9 on the roof of the oven chamber through the ceiling of the oven chamber and into the oven chamber itself. A vertically movable rack attachment means such as frame 11 for attaching to a rack 13 is fitted to the lower end of the shaft. Shaft 7 can be rotated by conventional means which are not shown. Shaft 7 is vertically movable by the rack lifting system. The rack lifting system comprises a horizontal rotatable plate 15, which is mounted around the shaft 7 and can rotate around the shaft independently of it. The rotatable plate comprises two horizontal extendable or telescopic arms 19 to which a curved door (not shown) can be attached. When the door is swung from the closed position in front of oven chamber opening 23 shown in figure 1 to the opened position shown in figure 2 it and rotatable plate 15 rotate around vertical shaft 7. Rotatable plate 15 has a vertical wall 25 provided a vertically extending guide slot 27.

Rotatable plate is further provided with a pair of cams 29 with cam upper surfaces 31 with profiles which vary in height from a low position to a high position. The cams are arranged in arcs on opposite sides of the shaft 7. A cam follower 39, for example, in the form of a rigid horizontal bar is attached to shaft 7. Cam follower 39 rests on the cam surfaces 31 and extends into guide slot 27. Rotation of door 21 by an operator rotates rotatable plate 15 which causes guide slot 27 to pull the cam follower 39 along the cam surfaces 31. The vertical guide slot 27 allows cam follower 39 to rise and fall as it follows the cam surfaces 31 and thus causes the shaft 7 to rise or fall correspondingly (and thereby lifting or lowering frame 11 and any rack 13 suspended from it). The cam surfaces are arranged so that when the door is in the closed position the shaft 7 and the frame 11 are at a high position and the rack is suspended above the floor, and when the door is in its open position the shaft and the frame are at a low position and the rack is on the floor. Thus rotation of the door automatically raises and lowers the rack as shown by the arrows in figures 3 and 4.

Extendable or telescopic arms 19 are each provided with a resilient means such as a spring 35 which is arranged to push the arms and the attached door away from the center of the oven. Longitudinally movable and lockable stop rings 24 (shown by dotted lines) can be provided to restrict the movement of the arms 19. These arms 19 ensure that when the door is released from its closed position it is automatically pushed out of the door opening 23 by the force of the springs. Movement of the door into the opening when the door is being slid to its closed position can be achieved by adding a suitably positioned and shaped cam surface or track (not shown) which projects from the outside of the oven and which cooperates with a cam or track follower on the door to guide the door into the door opening as it slides from the open position to the closed position.

Figures 7 to 9 show an embodiment of a means 51 for tilting and locking an oven door 21 when it is being opened (called "tilting means" in the following for brevity) for use on an oven in accordance with the present invention. This embodiment provides "a door steering device"-functionality which provides the door to slide lifted and tilted, from an open position to a closed, lowered, tightened and locked position. The cam system illustrated in figure 5 is also applicable in the embodiment described in connection with figures 7 to 9. When an oven door is closed it is desirable that it seals firmly against the edges of a door opening so that hot air is not lost from the oven. This is readily achieved with hinged doors which are normally pushed into the door opening but it is less easy to achieve with doors that slide in from the side to position in front of the door opening. Such doors preferably should be forced inwards to compress the seals to ensure an airtight seal. The embodiment of a tilting means shown in figures 7 to 9 is adapted to suspend a door by its upper end only, for example by upper edge 53, to support it at an inclined angle a in which the upper edge of the door is further way from the door opening than the lower edge 54 of the door while the door is being moved from an open position to a closed position, and to tilt the door so that it is substantially vertical with its edges in sealing contact with the edges of the door opening. Such a tilting means replaces the extendable or telescopic arms of the device described above. This is achieved by suspending the upper edge of door from a tiltable door tilting box 57 which can be tilted about a substantially horizontal axis in response to being displaced radially from the center of the oven along a pair of inclined ramps 59 mounted on the rotatable plate 15. Door tilting box has a horizontal base 61 attached to the upper edge 53 of the door and extending towards the rotatable plate 15, a vertically extending front wall 63 over the upper edge of the door and two radially arranged stiffening side walls 67. The door tilting box is pivotingly connected to the vertical wall 25 of the rotatable plate by a pair of outwardly biased extendable arms 69 which act to push the top of the door away from the oven opening. To achieve this, the outwardly biased extendable arms 69 are attached near the bottom 71 of the vertical wall of the rotating plate and extend to near the top 73 of the front wall 63 of the door tilting box. A pair of adjustable shroud screws 75 is pivotingly connected to the upper part 77 of the vertical wall of the rotatable plate and the respective closest end 79 of the side wall 67. The inclined ramps 59 on the rotatable plate 15 are arranged so that as the outwardly biased extendable arms 69 push the door outwards when the door tilting box 57 climbs up the ramps 59. This can be facilitated by providing the door tilting box with wheels 78 (or other low friction means such as low friction surfaces) which rest on the ramps 59. In a preferred embodiment of the invention the ramps are in the form of toothed racks and the wheels are gear wheels joined by which cooperate with the teeth on the rack. The gear wheels are joined by a rigid shaft 80 to ensure that the movement of the door tilting box is the same on both racks. Owing to the positioning of the attachment of the shroud screws to the side walls 67 of the door tilting box, this movement causes the ends 79 of the side walls 67 closest to the shroud screws to rise in an arc (shown by a curved arrow in figure 9) which pivots the door tilting box (and the door) about its contact point on the inclined ramps. In the door open position, as shown in figure 9, the extendable arms are fully extended and the door is tilted with its upper edge 53 further away from the oven than its lower edge 54. This has the advantage that hot air escaping via the open door opening will escape from the top of the opening and will not normally come into contact with the operator until the door is slid to one side. As the door is tilted it is also raised and the distance between the ground and the lower edge 54 of the door increases. A seal 95 can be provided on the lower edge of the door to seal against the ground or floor of the oven when the door is in its closed position. Preferably the seal is resilient and during the first part of the lifting and tilting movement expands to remain in contact with the ground to prevent hot air escaping and coming into contact with the feet of an operator.

In order to force the door back into the door opening during closing of the door, the underside 83 of the door tilting box and the upper surface 85 of the oven roof are provided with door closing means such as mutually co-operating cam means, for example a cam roller 87 on the underside 83 of the door tilting box and a cam surface 89 on the roof. These are arranged such that as the door is moved by an operator towards the closed position the cam roller 87 contacts the cam surface 89 and is forced towards the center of the oven. This pulls the door tilting box and the attached door towards the door opening, against the force of the outwardly biased extendable arms and causes the door tilting box to descend down the ramps 59. As the door closing movement is continued and completed the door is tilted upright and firmly pulled against the door seals 91 as shown in figure 8. The door closing means, e.g. the cam surface, can be provided with an indexing portion 93 which cooperates with the cam roller and holds the door in the closed position. The door closing means is arranged so that movement of the door into the door opening preferably starts when the door is at, or is less than, 15 cm from its closed position, more preferably when the door is at, or is less than, 10 cm from its closed position and most preferably when the door is at, or is less than, 6 cm from its closed position.

Claims

1. Rack oven with a door opening and a vertically movable rack attachment means for lifting a rack arranged in an oven chamber of said rack oven, characterized in that said rack oven is provided with an essentially circular horizontal cross-section and that it comprises a curved sliding door (21) which is movable along the outside of the oven in an arc from an open position away from the door opening to a closed position in front of said door opening, said oven comprises a rack lifting system (3) arranged on the roof (5) of the oven wherein said rack lifting system is attached to said curved door and adapted to control said movable rack attachment means so that said rack attachment means (11) moves from a low position when the door is in the open position to a high position when the door is in its closed position.

2. Rack oven according to claim 1, characterized in that said rack lifting system (3) comprises a horizontal rotatable plate (15), to which said door is attached, said plate is mounted around a rotatable vertical shaft (7) and can rotate around the shaft independently of it, said shaft (7) extends from a mounting system (9) on the roof of said oven chamber through the ceiling of the oven chamber and into the oven chamber itself, and that said movable rack attachment means is fitted to the lower end of the shaft, and wherein said shaft (7) is vertically movable by the rack lifting system.

3. Rack oven in accordance with claim 1 or 2, characterized in that it is provided with door tilting means which are adapted to tilt said door away from the door opening when the door is moved out of its closed position.

4. Rack oven in accordance with claim 3, characterized in that when said door is moved out of its closed position said door tilting means is adapted to said door away from the door opening so that the upper edge (53) of the door is further away from the door opening than the lower edge (54) of the door is.

5. Rack oven in accordance with claim 3, characterized in that said door tilting means is adapted to lift the door at the same time that it is moved from its closed position towards its open position.

6. Rack oven in accordance with any of the previous claims, characterized in that it is provided with door closing means which are adapted to pull the door into the door opening.

7. Rack oven in accordance with claim 6, characterized in that it is provided with door closing means which are adapted to tilt the door upright as it is moved into the door opening.