GB2299740A - Bakers' oven - Google Patents

Abstract

An oven module, with variable speed tray transporter, consists of a baking chamber in the form of an insulated enclosure which receives temperature controlled conditioned air through a series of inlet ducts from a heat exchanger and where the baking trays, which carry the loaf or other tins, slidungly fit between angle brackets which form the cross members of an endless belt system so that the trays 2 can be elevated up one side of the oven module and then rest at its roof in an idling position until a set of angle brackets on the other side of the oven becomes into register with the tins whereupon a tray transfer mechanism 10 simply pushes the tray across to an empty set of descending brackets 3 which carry the baked product down the oven and out to a discharge chute for cooling, slicing and packing. The speed of ascent and descent can be varied independently.

Description

Oven Module With Variable Speed Tray Transporter This invention relates to a bakery oven in the form of modular chambers each of which can have the speed of their tray transporters controlled separately by a programmed microprocessor. In particular it relates to a continuous bakery oven where the speed control of the moving product,on trays, is also inter-related with process control of temperature,relative humidity and air flow.

Ovens incorporating both vertical and horizontal(tunnel) movement of the product within their structures are well known and described in the prior art as is the case in FR.2346975 where a common external loading conveyor is used to load each level in the oven in turn and where each level is closed at the oven front by a pair of swinging pivoted plates so that the lower plate of the pair serves as a product discharge chute, or again,as in BE.843974 where a tunnel oven consists of a multiple stage cooking enclosure which has fermentation supports outside the oven but which are level with conveyor belts in the oven and where similiar supports are provided on the other side of the tunnel oven to receive the cooked loaves.

There is a need for an oven which will be capable of maintaining a number of cooking climates in terms of temperature,humidity,air flow and tray transport velocity and such an oven is the subject of the present invention where there is provided a baking chamber in the form of a stainless steel insulated enclosure which includes a number of separate baking modules all of which are fed with heated condit ioned air through central ducts from an external heat exchanger and where this air flows over the moving trays transporting the product and where the trays elevate on one side of the module, transfer across at the top and then descend to the bottom where their loaf tins,and the like,leave by a tray out-feed mechanism but which on their transport through the oven module can have their ascent and descent velocities varied independently according to a pre-programmed baking schedule.

A specific embodiment of the invention will now be described by way of wxample with reference to the accompanying drawings in which: Figure. 1. shows in diagramatic form the box shape of an oven module indicating the transport directions of the loaf tin carrying trays together with the direct- ional movement of the tray infeed and outfeed mechanisms.

Figure.2. shows in diagramatic form the same box shaped oven module of Figure 1 indicating the conditioned air flow directions within the oven.

Referring to the drawings the oven module with variable speed tray transporter comprises a stainless steel enclosure 1 having double walls whose cavity is insulated with mineral wool and where sets of baking trays 2 and 3 are spaced and placed on two endless chain belts which are driven by shafts 4,5,6 and 7 so that the set of trays 2 continuously ascend in the oven in the fashion of an elevator and the set of trays 3 continually descend in the oven in a similiar manner but where the movement of the two sets can be controlled and be different because of computer programming of the drives to each pair of shafts0 At the bottom of the oven module there is provided a tray in-feed system 8 which allows the baking trays to be placed on the elevator set 2 of the oven and a similiar tray out-feed 9 which is used to expell or discharge the baked products on their trays in their loaf tins.When the oven is in action, but not in the baking mode, the elevators are seen to consist of a set of endless chains across which are fixed pairs of angle iron which serve as moving supports for the baking trays. In the roof of the oven module there is a transfer mechanism 10 which simply pushes the tray,with its loaf tins,across to the descending set of tray brackets 3.The latter transfer movement is comput- er controlled and the transfer is accomplished by slipping the auto-clutch of the drive to the set of trays 2 at the point where a tray reaches its top position in the oven and then holding this stationary position until a set of angle brackets, or tray supports,becomes level with it at which point the auto-clutch in the series 3 transporter slips and simultaneously the transfer mechanism 10 operates to push the tray and its products across to the receiving angle brackets when thereafter both auto-clutches engage and the endless chain belts move again at their respective set speeds. This described movement is a simple operation within the oven module because the chain belts move slowly as can be gauged from the fact that the baking, or in-oven,times can be as short as 15 minutes or as long as 1 hour.The placement of the power drives to each set of tray transporter is simplified by driving the top set of shafts with one motor for the elevator and the bottom set with another motor for the descending transporter. Heat energy to the oven module is via a gas or oil fired heat exchanger and is delivered to a central duct 11 from which it rises and flows,as hot air,over the elevating and descending tray transporters 2 and 3. This hot air leaves the oven module through adjustable,perforated air baffles 12 and 13 and from these to end ducts 14 and 15 which lead back to the inflow of the heat exchanger. The adjustable baffles are used to obtain the required thermal distribution to cater for baking needs. A commercial oven, based on this described innovation can efficiently contain up to four modules and each can be computer controlled in terms of temperature,relative humidity, hot air flow and tray velocities so that it is simple to arrange the execution of the whole range of baking procedures such as fermentation, proving, cooking or partial cooking and final crust formation.

Claims (7)

1. l.A baking chamber in the form of a stainless steel insulated enclosure which includes a number of separate baking modules all of which are fed with heated conditioned air through central ducts from an external heat exchanger and where this air flows across moving trays transporting the product and where the trays elevate on one side of the module,tranafer across at the top and then descend to the bottom where they, and their loaf tins,leave by an actuator push-out arm but which on their transport through the oven can have their ascent and descent velocities varied independently according to a pre-programmed baking schedule.
2. 2.A baking chamber according to Claim 1 wherein the trays are accomodated on angle brackets acting as cross-members on an endless belt system whose autoclutch drive can be stopped so that once at the roof of the module a tray can be held in an idle drive condition until it becomes in register with an empty position in the descending belt whereupon an actuator pushes it across to enable it,with the product,to descend in the oven.
3. 3.A baking chamber according to any of the above Claims wherein the trays,with their dough in tins,are automatically fed into empty positions on the ascending angle bracket supports.
4. t.A baking chamber according to any of the above Claims wherein the finished product in loaf tins on the descending trays are automatically expelled to a receiving conveyor to be taken for cooling, slicing and packaging.
5. 5.A baking chamber according to Claim 1 wherein the air supplied to the central ducts is computer controlled in terms of relative humidity, temperature and velocity so that control programmes can be selected automatically for the purposes of fermentation, conditioning,proving and baking.
6. 6.A baking chamber according to Claim 5 wherein the hot air leaving the oven modules passes through perforated air baffles to ducts which lead back to the heat exchanger for re-cycling and heat conservation purposes.
7. 7.A baking chamber substantially as described herein with reference to Figures 1 and 2 of the accompanying drawings.