Abstract:
A baking oven comprises a charging section with an inlet for dough pieces to be loaded; a baking chamber; and a discharging section with an outlet for baked dough pieces to be unloaded. Provision is made for a circulating-air arrangement with a source that generates a flow of circulating air, a circulating-air heating device, and a circulating-air guiding channel, sections of which are formed by the baking chamber. An outer wall of the baking chamber is rotationally symmetrical about a vertical axis of rotation, expanding steadily upwards in particular in the shape of a funnel. A baking oven results, in which the dough pieces can be moved and distributed as regularly as possible during baking.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a baking oven comprising a charging section with an inlet for dough pieces to be loaded; a baking chamber; a discharging section with an outlet for baked dough pieces to be unloaded; a circulating-air arrangement, which is comprised of a source generating a flow of circulating air, a circulating-air heating device, and a circulating-air guiding channel, at least sections of which are formed by the baking chamber. 
     2. Background Art 
     A baking oven of the generic type has been disclosed by prior public use. Baking ovens of the species are still in need of improvement regarding the baking time of dough pieces and the possibilities of implementation. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to further develop a baking oven of the type mentioned at the outset in such a way that reduced baking periods can be achieved, accompanied with simultaneously improved handling of the baking oven. 
     According to the invention this object is attained with a baking oven comprising a baking-chamber outer wall which is rotationally symmetrical about a vertical axis of rotation, expanding steadily upwards in particular in the shape of a funnel; and a driving device, by means of which the outer wall is driven in rotation about the axis of rotation. 
     According to the invention it has been found that more efficient baking of dough pieces will result when the dough pieces are moved in a flow of circulating air and when they are distributed as uniformly as possible within the baking chamber. Moving the dough pieces within the baking chamber and distributing them as uniformly as possible can be put into practice by the baking chamber having an outer wall that is shaped and actuated according to the invention. 
     A baking chamber that has an additional inner wall offers more favourable conditions of flow for the circulating air that streams through the baking chamber. 
     Yet another improvement of the circulating-air flow behavior is attained with an inner wall that is rotationally symmetrical about a vertical axis of rotation, steadily expanding upwards, in particular in the shape of a cone and parallel to the outer wall. 
     Uniform circulating-air flow in the baking chamber can be obtained with an inner wall that has circulating-air passages. Moreover, it is possible to adapt the position of the circulating-air passages to the shape of the baking chamber so that circulating air of equal temperature streams through nearly the entire baking chamber, which works in favour of uniform baking results. 
     A baking-chamber closing arrangement, which is disposed at the bottom of the baking chamber and which is displaceable by an actuator between a baking position, in which the baking-chamber closing arrangement closes the baking chamber at the bottom, and a position for discharge, in which it produces a connection between the baking chamber and the discharging section, enables the baked dough pieces to be discharged automatically from the baking chamber. 
     A baking-chamber closing arrangement that forms part of the circulating-air guiding channel simplifies the constructional design of the baking oven. 
     Automatic discharge of the baked articles will take place in a particularly simple way when a slope is provided between the baking chamber and an outlet, the slope being part of the discharging section. 
     With the baking-chamber closing arrangement and an unloading door that closes the outlet embodied for controlled displacement, a controlled baking cycle can be put into practice, followed by fully automatic discharge of the baked articles. Such a baking cycle can be started automatically for instance by the addition of dough pieces into the charging portion of the baking oven. 
     An embodiment of the baking oven comprises a vacuum pump which is connected to the baking chamber and designed for controlled actuation and by which to set a given negative pressure in the baking chamber. This facilitates heating the baking chamber at the beginning of a baking process. 
     By alternative of, or in addition to, that preferred embodiment, provision can be made for a steaming assembly which is connected to the baking chamber and designed for controlled actuation and by which to supply the baking chamber with steam. The steaming assembly ensures controlled humidification of the dough pieces, meaning improved baking results. More uniform humidification of the dough pieces can be obtained when the steaming assembly cooperates with a vacuum pump, which will still further improve the baking result. 
     Details of the invention will become apparent from the ensuing description of an exemplary embodiment of the invention, taken in conjunction with the drawing. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a perspective outer view of a baking oven; 
     FIG. 2 is a perspective inner view, broken open, of the baking oven of FIG. 1 with a baking-chamber closing arrangement in a position for baking; and 
     FIG. 3 is an illustration, similar to FIG. 2, with the baking-chamber closing arrangement in a position for discharge. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The baking oven, which is designated in its entirety by the reference numeral  1  in FIG. 1, comprises a oven casing  2  of a square base of 1 m 2  and a height of approximately 2 m. Dough pieces  3 , for instance deep frozen or partially defrosted rolls, are fed into the interior of the baking oven  1  via an inlet  4  that can be closed by a loading door  5  which is preferably manually operated and shuts tightly. The inlet  4  is followed by a doorway  6  that leads to an annular baking chamber  7 , the diameter of which increases upwards. The baking chamber  7  is rotationally symmetrical and defined outwards by a funnel-shaped, outer wall  8  that expands upwardly. The baking chamber  7  is defined inwards by a conical inner wall  9  that expands upwards in cross-sectional shape. The baking chamber  7  and the walls  8 ,  9  have a joint, vertical axis of symmetry  10 . 
     The inner wall  9  is supported by a holding bar  11  which extends centrally along the axis of symmetry  10 , the holding bar  11  being carried by a holding plate  12  which is disposed above the doorway  6  in the oven casing  2 . 
     The outer wall  8  is rotatable about the axis of symmetry  10 . To this end, it is mounted in the vicinity of the bottom of the baking chamber  7  by three ball bearings which are regularly distributed around the axis of symmetry  10  in the circumferential direction, forming a first radial bearing  13  for the outer wall  8 . The first radial bearing  13  as well as the bearings described below are illustrated only diagrammatically in the drawing. On the side of the casing, the first radial bearing  13  is mounted on a first intermediate bottom  14  in the oven casing  2 . 
     In the upper part of the baking chamber  7 , above a horizontal boundary wall  15  of the inner wall  9 , the outer wall  8  is connected to an inner bearing sleeve  17  by way of three cross struts  16  that are regularly distributed in the circumferential direction, the sleeve  17  rotarily enclosing the holding bar  11 . The inner bearing sleeve  17  is housed in an outer bearing sleeve  20  for rotation about the axis of symmetry  10  by way of a second radial bearing  18 , which is an encircling ball bearing, and an axial/radial bearing  19 , which comprises two encircling ball bearings. The sleeve  20  is tightly joined to a second intermediate bottom  21 , disposed above the cross struts  16 , of the baking oven  1 . The inner bearing sleeve  17  supports a horizontal driving pulley  22  that encloses the holding bar  11  and can be driven via a V belt  23  by a driving motor (not shown). The driving motor serves for rotation of the outer wall  8  of the baking chamber  7  about the axis of symmetry  10 . 
     The baking chamber  7  is defined downwards by a baking-chamber closing arrangement  24  with a cylindrical jacket wall  25  that is covered upwards by a convex grid  26 . The baking-chamber closing arrangement  24  is displaceable between a baking position seen in FIG. 2 and a position for discharge seen in FIG.  3 . Via a joining element  27  and a slide rod  28 , the jacket wall  25  is connected to a lifting cylinder  29  which is supported by a third baking-oven- 1  intermediate bottom  30  which is disposed below the baking-chamber closing arrangement  24  and heat-insulated. In the baking position, the outer peripheral area of the grid  26  of the baking-chamber closing arrangement  24  bears directly against a funnel-shaped baffle  31  that is mounted on the bottom end of the inner wall  9 . 
     The baking chamber  7  is heated by heated circulating air that is generated by a fan  32  with an electric heating element  33 ; the fan  32  is supported by the second intermediate bottom  21 . Circulating air heated by the heating element  33  passes through a first circulating-air guiding channel section  34  which is formed between a lateral inside casing wall  35  and a baking-chamber-casing wall  36  that envelops the outer wall  8 . As roughly outlined in FIG. 2 by arrows of flow direction  37 , the circulating air passes from the first circulating-air guiding channel section  34  into a circulating-air collecting chamber  38  that is disposed between the first intermediate bottom  14  and the third intermediate bottom  30 . The circulating air passes from the circulating-air collecting chamber  38  into the baking-chamber closing arrangement  24  that is open downwardly, from where it flows through the grid  26  and, guided by the baffle  31 , through holes in the baffle  31  and into the inner wall  9 . Passages in the inner wall  9  admit the circulating air to the baking chamber  7 , which is shown in FIG. 2 by the arrow of flow direction  39 . The holes in the baffle  31  and the passages in the inner wall  9  are not shown in the drawing. The circulating air leaves the baking chamber  7  via a second circulating-air guiding channel section  40  in a direction towards the fan  32 . 
     FIG. 3 illustrates the baking-chamber closing arrangement  24  in a position for discharge, in which it is displaced downwards, as against the baking position, by the aid of the lifting cylinder  29 . This leaves open an aperture  41  in the first intermediate bottom  14  of the baking chamber  7 . The round aperture  41  connects the baking chamber  7  to an unloading passageway  42  that has a slope  44  towards an outlet  43 . The outlet  43  can be shut by a motor pivoted unloading door  45 . A baked-article collecting box  46  is disposed below the outlet  43 . 
     The baking oven  1  is operated as follows: 
     The loading door  5  is opened for the baking oven  1  to be loaded with a charge of for example 45 rolls. At this time, the baking-chamber closing arrangement  24  is in the baking position. Then the dough pieces  3  are led into the baking oven  1 , sliding through the doorway  6  into the baking chamber  7  and collecting on the bottom of the baking chamber  7  that is closed by the closing arrangement  24 . Then the outer wall  8  is set rotating by the driving motor and the fan  32  and the heating element  33  are activated. By reason of the centrifugal force occasioned by rotation of the outer wall  8 , the dough pieces  3  are distributed uniformly on the outer wall  8  and within the baking chamber  7 . Simultaneously, the dough pieces  3  are heated and baked by the heated circulating air that passes through the baking chamber  7 . After termination of the baking process, rotation of the outer wall  8  is stopped or distinctly reduced for the baked dough pieces  3  to collect on the bottom of the baking chamber  7  under the action of gravity. With the aid of the lifting cylinder  29 , the baking-chamber closing arrangement  24  is moved by timed actuation into the position for discharge of FIG.  3 . Simultaneously the unloading door  45  opens by timed control. The baked dough pieces  3  leave the baking chamber  7  through the aperture  41  under the action of gravity, sliding along the slope  44  towards the outlet  43  and falling through it into the baked-article collecting box  46 . The baking time is approximately 12 minutes. 
     An embodiment (not shown) of the baking oven  1  additionally comprises a vacuum pump by which to set given negative pressure in the baking chamber  7 . Simultaneously, this embodiment of the baking oven  1  includes a steaming assembly, known per se, by which to supply water vapor to the baking chamber  7 . 
     In this embodiment, the baking chamber  7  is evacuated by the vacuum pump at the beginning of the baking process so that the dough pieces  3  in the baking chamber can be heated more rapidly by the circulating air. Interaction of the vacuum pump and the steaming assembly helps obtain more efficient humidification of the dough pieces by steam. 
     In keeping with another embodiment (not shown) of the baking oven, the job of opening and closing the loading door  5  is controlled automatically.