CH711637B1

CH711637B1 - Cooking appliance with controllable ventilation.

Info

Publication number: CH711637B1
Application number: CH01235/04A
Authority: CH
Inventors: Schiller Udo; Dubach Urs
Original assignee: V Zug Ag
Priority date: 2004-07-21
Filing date: 2004-07-21
Publication date: 2017-04-13
Also published as: EP1619443A3; SI1619443T1; EP1619443A2; PL1619443T3; EP1619443B1; DK1619443T3

Abstract

A cooking appliance has a blower (6) which conveys air from a suction area (7) into a pressure space (8). A first opening (14) connects the cooking space (1) to the pressure space (8). A temperature sensor (18) is arranged at the opening of the first opening in order to detect emerging vapors. A second opening (20) connects the cooking chamber (1) to the suction region and is closed by a controllable closure (21). The shutter (21) is opened when the temperature sensor (18) detects the vapors passing through the first opening (14). Since the vapors have to overcome the overpressure prevailing in the pressure chamber (8) during the discharge through the first opening (14), the temperature sensor (18) only detects a vapor outlet when a certain overpressure prevails in the cooking chamber (1). The closure (21) is therefore only opened, When excessive steam is generated in the cooking chamber (1). It is shown that this measure reliably regulates the moisture in the cooking chamber (1) and the energy loss can be reduced.

Description

Description [0001] The invention relates to a cooking appliance according to the preamble of claim 1.

[0002] EP 1 156 282 discloses an oven whose cooking chamber has two openings. In the case of a first of these openings, a sensor is provided for detecting exiting vapors. The second opening is arranged with a fan. If vapors emitted by the sensor are detected, the fan is switched on or amplified, so that the vapors emerging through the second opening are conveyed away. It is also proposed to arrange a controllable slide at the second opening.

[0003] It is an object of the invention to reduce the energy consumption of this device.

[0004] This object is achieved by the cooking appliance according to claim 1.

[0005] According to the invention, the cooking appliance is designed in such a way that the blower produces an overpressure in the downstream pressure chamber. The first opening opens into this pressure chamber. This leads to the fact that the vapor must overcome the overpressure prevailing in the pressure chamber when it exits through the first opening. Thus, during the first opening, the sensor detects a vapor outlet only when a certain overpressure prevails in the cooking chamber. Therefore, the sensor only responds when excessive steam is actually generated in the cooking cavity. It can be seen that the energy loss can be reduced by this measure, without the moisture in the cooking space increasing impermissibly.

[0006] Preferably, the second opening opens into the suction area of the fan so that the vapors are efficiently conveyed away when the closure is opened.

[0007] Further preferred embodiments result from the dependent claims as well as from the following description with reference to the figures. In this connection:

FIG. 1 is a schematic view of the most important components of a cooking appliance and FIG

FIG. 2 shows an example of possible temperature variations in the cooking chamber and the temperature sensor (upper graphic) and the position of the closure of the second opening (lower graphic).

The cooking appliance according to FIG. 1 has a cooking space 1, which is delimited by walls 2 and a door 3. The cooking appliance shown as an example can be operated both as an oven and as a steam cooker. Correspondingly, it has, in addition to conventional resistive heaters (not shown), a steam generator 4 as described, for example, in EP 1 166 694.

[0009] Outside the cooking chamber 1, an external air fan 6 is arranged as a blower. This conveys air from a suction area 7 into a pressure space 8. From the pressure space 8, the conveyed air exits into the environment through a front-side outlet opening 9 of the appliance. The pressure chamber 9 is delimited upwards by an inclined cover plate 10 and downwards by an inclined bottom plate 11, such that the pressure chamber 8 tapers towards the outlet opening 9. On the side, the pressure chamber is closed by side walls (not shown).

[0010] Two openings are arranged in the ceiling of the cooking space 1, which are approximately of the same size and each have, for example, a diameter of approximately 2.5 cm.

A first opening 14 leads from the cooking space 1 into the interior space 15 of a protective housing 16. The protective housing 16 is arranged in the pressure space 8 and communicates with the latter via a connection opening 17. The connection opening 17 is located on the side of the protective housing 16 remote from the fan A temperature sensor 18 is arranged in the protective housing 16 at the opening of the first opening 14. The first opening 14 is always open.

A second opening 20 connects the cooking chamber 1 to the suction region 7 in front of the blower 6. To close the second opening 20, a closure 21 is provided which consists of a flap 22 which is more or less of a stepping or servo motor 23 Can be pushed far beyond the mouth of the opening 20 such that the closure can be transferred substantially continuously from a closed to an open position.

For controlling the steam generator 4, the shutter 21 and the further components of the cooking appliance, a control unit 24 is provided which, inter alia, monitors the temperature signal emitted by the temperature sensor 18.

During operation of the cooking appliance, the blower 6 is continuously operated. It sucks air through openings in the back wall and in the side walls of the cooking appliance from the environment. This air passes through the suction area 7, is blown into the pressure space 8 and leaves it through the outlet opening 9. Since the pressure space 8 is tapered toward the outlet opening 9, a slight overpressure is produced in the pressure space 8.

[0015] Thus, an object of the blower 6 is to discharge air to the outside for cooling the appliance, which has heated on the outside of the cooking space.

[0016] The function of the cooking appliance depends on whether it is used as a steaming appliance or as a conventional thermal oven.

Claims

[0017] In conventional operation, the food to be cooked or the cooking space 1 is heated by means of the resistive heaters (not shown). As shown in FIG. 2, the cooking chamber temperature Tgr can rise above 100.degree. At the beginning of a conventional cooking phase, as illustrated in FIG. 2, the shutter 21 is in the closed position since the controller 24 is designed to set the temperature at the temperature sensor 18 to a predetermined value Tr of, for example, 63 ° C. If the temperature Tgr of the cooking chamber rises above 100 ° C., a more or less pronounced steam outlet occurs from the food to be cooked. As a result, the pressure in the cooking chamber 1 increases. If this pressure exceeds the pressure in the pressure chamber 8, the vapor passes through the first opening 14 into the interior 15 of the protective housing 16 and thus into the pressure chamber 8. In so doing, it sweeps past the temperature sensor 18 so that the temperature Ts measured by it rises. When the temperature Ts approaches or exceeds the value Tr, the controller 24 starts opening the second opening 20 by actuating the stepping motor 23. The cooking chamber 1 is connected via the second opening 20 to the suction region 7 where a relatively low pressure prevails so that the vapors are discharged through the opening 20 and the excess pressure in the cooking space 1 is discharged. The pressure gradient between the pressure space 8 and the cooking space 1 is reversed, and only cooler and more dry air exits the pressure space 8 into the cooking space, as a result of which the temperature sensor 8 cools so that the controller 24 closes the closure 21 again. Thus, the controller 24 thus forms a control loop, By more or less strongly opening the shutter 21, to keep the temperature Ts at the sensor 18 approximately at the value Tr. If the steam generation rate in the cooking space 1 exceeds a certain value, for example when cooking a relatively large, moist food product, the closure 21 remains completely open (as shown in FIG. 2) and the temperature Ts at the sensor 18 clearly exceeds the value Tr , Until the steam generation rate decreases again. If the temperature at the temperature sensor 18 remains low and no vapors exit is thus observed, the controller 24 preferably closes the closure 21 completely, so that no further vapors can escape and an unnecessary energy loss is avoided. In this way, vapors are discharged from the cooking chamber 1 as needed. At the same time, however, the blower 6 can remain in operation continuously and independently of the temperature value Ts of the sensor and thus cool the cooking appliance. A separate blower for extracting excess vapors from the cooking chamber 1 is not required, a cross-flow fan is sufficient. During operation as a steam cooker, the closure 21 normally remains closed. The control, however, in turn monitors the temperature Ts at the sensor 18 and uses it to control the power of the steam generator 4 in the manner described in EP 1 166 694. Optionally, the closure 21 can be opened at the end of the steam-powered operation and the steam can thus be discharged from the cooking chamber 1. At the same time, more dry air is introduced into the cooking chamber 1 via the first opening 14. Thus, the opening 14 and the temperature sensor 18 can be used in both modes for the device control. In this case, the protective housing 16 shields the temperature sensor 18 from the air coming from the blower 6, so that the temperature sensor 18 can already detect small amounts of exiting vapor or steam. When the door 3 is closed, the cooking chamber 1 is gas-tight except for the first and second openings. This prevents the steam from escaping uncontrolled from the cooking chamber and causing, for example, moisture damage in the steam cooking operation. In conventional furnace operation, the air exchange with the environment takes place in a controlled manner via the openings 14 and 20. As mentioned, the temperature Tr can be a fixed, predetermined value. However, it can also be selected as a function of the temperature in the cooking chamber 1. It can thus be taken into account that the vapors emerging from the hot cooking chamber have a higher temperature, which allows a more accurate detection of the wafers and thus a better regulation of the appliance. Depending on the food to be cooked, it may also be expedient to control the closure 21 independently of the signal of the sensor 18. For example, in the case of products which require a great deal of moisture, the shutter 21 can be kept partially or completely open at least in a program phase, independent of the temperature at the sensor 18. For this purpose, the cooking appliance can be designed such that when a cooking appliance is selected, During at least one part of the program, the shutter 21 is held at least partially open independently of the sensor 18. A suitable sensor, as described in EP 1 156 282, can also be used as a sensor for detecting the leakage emerging through the first opening 14 instead of a temperature sensor. claims

(EN) The invention relates to a cooking appliance (1) comprising a cooking chamber (1), a blower (6) for conveying gas from a suction region (7) outside the cooking space (1) In the cooking chamber (1), a sensor (18) for detecting vapors emerging through the first opening (14), a second opening (20) in the cooking chamber (1) spaced from the first opening (14) and a shutter (21) for closing the second opening (20) and a shutter control (24) for controlling the shutter (21) as a function of a signal from the sensor (18), characterized in that the blower (6) for generating an overpressure in the pressure chamber 8), and in that the first opening (14) opens into the pressure space (8).
2. The cooking appliance as claimed in claim 1, characterized in that the second opening (20) opens into the suction region (7).
3. The cooking appliance as claimed in claim 1, characterized in that the pressure chamber (8) has an outlet opening (9) for delivering air conveyed by the fan (6) to the environment, and in particular the pressure chamber (8) (9).
4. The cooking appliance as claimed in claim 1, characterized in that a protective housing (16) is arranged in the pressure chamber (8), wherein the first opening (14) opens into an interior space (15) of the protective housing (16) (15) communicates with the pressure space (8) via a connecting opening (17), which communicates with the pressure chamber (8) on a side facing the blower (15) 6) facing away from the protective housing (16).
5. The cooking appliance as claimed in one of the preceding claims, characterized in that the sensor (18) is a temperature sensor arranged at the mouth of the first opening (14).
6. The cooking appliance as claimed in claim 1, wherein the closure control is configured as a control circuit which, by opening and closing the closure, adjusts a temperature at the sensor to a set temperature Rules.
7. The cooking appliance as claimed in claim 1, characterized in that the closure control (24) opens the closure (21) increasingly on detection of an increasing vapor outlet through the first opening (14), and in particular, when the vapor outlet is detectable closes.
8. The cooking appliance as claimed in one of the preceding claims, characterized in that the blower (6) is a cross-flow fan.
9. The cooking appliance as claimed in claim 1, characterized in that it is designed in such a way that the fan (6) removes air, which has heated on the outside of the cooking space (1), for cooling the appliance externally.
10. The cooking appliance as claimed in one of the preceding claims, characterized in that the blower (6) is operated independently of the signal of the sensor (18).
11. The cooking appliance as claimed in claim 1, characterized in that it is configured as a combined thermal oven and as a steam cooker and, in addition to at least one resistive heating for the cooking chamber (1), a steam generator (4) for introducing steam into the cooking space (1 ), And in that it is configured to control a quantity of steam generated by the steam generator (4) as a function of a signal from the sensor (18) during operation as a steam cooker.
12. The cooking appliance as claimed in claim 11, characterized in that it is designed to open the closure (21) at the end of a steam cooking operation, in order to dissipate steam from the cooking space (1).
13. The cooking appliance as claimed in claim 1, characterized in that the cooking chamber (1) is gas-tight except for the first and second openings (14, 20).
14. The cooking appliance as claimed in claim 1, characterized in that the closure (21) can be transferred substantially continuously from a closed position into an open position.
15. The cooking appliance as claimed in claim 1, characterized in that it is designed such that it keeps the closure (21) at least partially open during at least one part of a cooking program, independent of the sensor (18).