EP1191286B1

EP1191286B1 - Oven provided with analyzer for the air present in its cooking chamber

Info

Publication number: EP1191286B1
Application number: EP20010119207
Authority: EP
Inventors: Andrea c/o Whirlpool Europe s.r.l. Corda; c/o Whirlpool Europe s.r.l. Comolli Massimiliano; Mauro c/o Whirlpool Europe s.r.l. Bolognesi
Original assignee: Whirlpool Corp
Current assignee: Whirlpool Corp
Priority date: 2000-09-20
Filing date: 2001-08-09
Publication date: 2008-10-08
Anticipated expiration: 2021-08-09
Also published as: EP1191286A3; ITMI20000530V0; DE60136043D1; IT250446Y1; ITMI20000530U1; ES2313923T3; EP1191286A2

Description

The present invention relates to a domestic oven in accordance with the introduction to the main claim.
Analyzers disposed within cavities of domestic ovens have been known for some time. These analyzers enable, for example, the state of preparation of food positioned in the cooking chamber or cavity of said ovens to be determined; alternatively or additionally, if said ovens are of the type in which pyrolytic cleaning (known per se) takes place, these analyzers enable the degree of completion of this cleaning to be determined by analyzing the gases generated within the cooking chamber during pyrolysis.
These gas analyzers (or gas sensors) can be of absorption spectrum analysis type or of catalytic/resistive type. They measure the content of CO, CO₂, hydrocarbons (HC) and/or other gaseous compounds present in the cooking chamber, which can derive either from food cooking processes or from the pyrolytic cleaning process.
Gas analyzers or sensors are used in those ovens in which here is no forced air circulation for cooling the oven. By means of suitable known electrical contacts, said analysis (carried out in known manner, for example by modifying the resistivity or voltage of a component of such analyzers which is related to the absorption of a particular gaseous compound by these latter) is "read" by a usual member for controlling the oven operation; the pyrolytic cleaning is, for example, halted on the basis of this reading.
These analyzers or gas sensors have been widely used in free-standing ovens; however, up to the present time they have not been used in built-in ovens, or in those ovens in which a fan is present to draw air from the cavity and expel it to the outside, as this forced circulation of the air present within the environment in which the sensor is positioned does not enable the corresponding gas analyzer to make contact with the air drawn from this chamber at a concentration sufficient to allow effective analysis.
JP-58150720 discloses a gas oven according to the preamble of appended claim 1, in which the movement of air around the analyzer is prevented.
An object of the present invention is therefore to provide an oven, preferably of built-in type, in which the composition of the air present in the cooking chamber can be analyzed, to enable the extent of cooking of a food present in said chamber or the state of advancement of pyrolytic cleaning (if the oven is prearranged for said cleaning) to be evaluated.
A further object us to provide an oven in which the air in the cooking chamber can be analyzed reliably and at low cost.
These and further objects which will be apparent to the expert of the art are attained by an oven in accordance with the accompanying claims.
The present invention will be better understood from the accompanying drawing, which is provided by way of non-limiting example and in which:

Figure 1 is a block diagram of the various components of the oven according to the invention;
Figure 2 is a view of a part of the oven of Figure 1, seen from above;
Figure 3 is a side view of the oven part of Figure 2;
Figure 4 is a block diagram of a variant of the invention.

With reference to Figures from 1 to 3, a built-in oven comprises a cooking chamber or cavity 1 connected to a suction member defined by a tangential fan 2. On its suction side the fan is connected via a conduit or channel 3 to the chamber 1 and via a conduit or channel 4 to an exit port B positioned on the upper side of the opening A of the chamber 1 so that the oven outer walls and the compartment in which the oven is mounted are cooled during oven operation. In the interspace defined by said oven outer walls and by the compartment walls there is mounted on the oven an electronic oven control member 5, which is hence cooled by the gas drawn in by the fan 2. The conduits 3 and 4 converge into a conduit 6 directly connected downstream to the fan 2.
At the exit of the cooking chamber 1 there is positioned in the suction conduit 3 a usual catalyst 10 for purifying the air leaving this chamber.
According to the invention, a by-pass channel 11 is connected to the conduit 3 and leads to a gas analyzer 12 of known type. This analyzer is connected, via a usual connection member 13, to the oven control member 5 in such a manner as to enable this latter to obtain data on the analysis of the air leaving the cooking chamber 1 and to operate on the oven 1, for example by interrupting the heating of the chamber 1 because the food under preparation therein has reached the desired extent of cooking.
The by-pass channel 11 comprises an outward conduit or branch 14 and a return conduit 16 connected respectively to the conduit 3 downstream of the catalyst 10 and to the conduit 6 upstream of the tangential fan 2.
In this manner, during use of the oven in preparing a food, by virtue of the suction action of the cooling fan 2 (which discharges the drawn air into the environment through a channel 15), the air is drawn from the chamber 1, passes through the catalyst 10 and transits towards the conduit 6. During this movement (shown by the arrows present in Figure 1) a portion of the indrawn air also flows into the by-pass channel 11, drawn into it by the fan 2 via the conduit 16. From the channel 11 the air reaches the gas analyzer 12, where it is analyzed known manner.
The effected analysis is "read" by the control member 5 which on the basis of this acts on the members heating the oven. If this latter is of the pyrolytic cleaning type, the aforesaid analysis can be carried out during this cleaning operation to enable the member 5 to halt the cleaning when suitable.
By virtue of the particular manner of connecting the analyzer 12 to the chamber 1, the air leaving this latter is able to encounter the analyzer for a time necessary and sufficient for it to analyze its composition.
In a variant shown in Figure 4 (in which parts corresponding to those of the already described figures are indicated by the same reference numerals), the return channel or conduit 16 is not connected to the conduit 6, but to the discharge conduit 15 downstream of the fan 2 in the air flow direction shown by the arrows of this figure. In this case the connection region between these conduits can be formed by suitably choosing the cross-section of the conduit 16 to enable the air present in the analyzer to remain therein for the time required for its analysis.
By means of the invention a gas analyzer can be used safely and reliably within a built-in oven for controlling at least the preparation of the food therein; if the oven is of the type provided with a pyrolytic cleaning member, the invention also enables the cleaning operation to be controlled.
As an alternative to connecting the exit of the by-pass conduit to a region upstream or downstream of the fan 2, a dedicated pump or fan (not shown) can be used to extract a determined gas throughput or to make it flow through the sensor. The solution according to the invention can be applied in both static and forced-circulation ovens.

Claims

An oven comprising an internal cavity or cooking chamber (1) connected to a suction conduit (3) operationally connected to a suction member (2) arranged to withdraw air from the interior of the cooking chamber (1) and to expel it into the environment in which the oven is positioned via a discharge conduit (15), and comprising an analyzer (12) for the air drawn from the cooking chamber (1), characterised in that said analyzer (12) is positioned within a by-pass conduit (11) connected to the suction conduit (3).
An oven as claimed in claim 1, characterised in that the by- pass conduit (11) has a first branch (14) connecting the suction conduit (3) to the analyzer (12) and a return second branch (16) leaving the analyzer.
An oven as claimed in claim 2, characterised in that the return second branch (16) is connected to an entry conduit (6) to the suction member (2), there being connected to said conduit (6) a conduit (4) connected to an oven control member (5) arranged to cool the oven.
An oven as claimed in claim 2, characterised in that the return second branch (16) is connected to the discharge conduit (15) leaving the suction member (2), there arriving at this member an entry conduit (6) to which there are connected the suction conduit (3) and a conduit (6) connected to an oven control member (5) arranged to cool the oven.
An oven as claimed in claim 1, characterised in that the by- pass conduit (11) is connected at its exit to an auxiliary pump or fan arranged to feed a determined gas throughput through the analyzer (12).