DE102012210854A1 - Cooking appliance with a reversible hot air motor in its direction of rotation - Google Patents

Abstract

Cooking device (11), comprising a hot air blower (13) with a hot air motor (15) and a cyclically operable heater (16), wherein a direction of rotation of the hot air motor (15) is reversible, the cooking device (11) being set up to adjust the direction of rotation in particular reversing specifically only during a phase out (apv; ap) of the heater (16).

Description

The invention relates to a cooking appliance, comprising a hot air blower with a reversible in its rotational direction hot air engine and a clocked operated heater.

In a known hot air blower of the type concerned, the hot air engine and the heater are turned on with each other, the engine is running permanently. The hot air engine is typically connected to an impeller, usually via a drive shaft. The heater is operated clocked to prevent overheating or for the purpose of temperature control. Reversing the direction of rotation of the motor can take several seconds. During the reversal of the direction of rotation of the engine, however, the radiator may overheat for lack of heat dissipation. In order to avoid such overheating of the heater, it has been known to reduce its power sufficiently far. However, a reduction in performance is disadvantageous because it can greatly change the cooking behavior of the cooking appliance.

It is the object of the present invention to at least partially overcome the disadvantages of the prior art and in particular to provide a possibility for improved reversal of the direction of rotation of a hot-air engine.

This object is achieved according to the features of the independent claims. Preferred embodiments are in particular the dependent claims.

The object is achieved by a cooking appliance, comprising a hot air blower with a reversible in its direction of rotation hot air engine and a clocked operated heater, wherein a direction of rotation of the hot air motor is reversible. The cooking device is set up to reverse the direction of rotation during a heating phase.

This cooking appliance has the advantage that overheating during the reversal of the direction of rotation can be avoided, since in the meantime the heating system produces no or only an insubstantial amount of heat during its phaseout. In turn, this may be e.g. Advantageously dispensed with a direct sensor for temperature detection in the vicinity of the heater or the heater can be designed without risk of overheating in the usual performance.

In other words, such a cooking appliance, for example an oven, is designed with a controller such that the direction of rotation is not or not substantially reversed during a one-phase heating, but is reversed at least predominantly during a phase-out of the heating.

The fact that the cooking appliance is set up to reverse the direction of rotation during an outage of the heating may in particular mean that the hot-air engine is transferred from a first speed in a first direction of rotation to a second speed in a second direction of rotation. The first direction of rotation and the second direction of rotation are reversed to each other and may be e.g. a clockwise or counterclockwise rotation, or vice versa. The first speed and the second speed may be the same or different.

The hot air engine is typically connected to an impeller, usually via a drive shaft. By reversing the direction of rotation, for example, a direction of the air conveyed and heated by the hot-air engine can be reversed. The heater may in particular have at least one annular heating element. The heating ring body, for example, surround the impeller.

Under the clocked operable heater is in particular a heater understood, which is supplied via on and Ausphasen with electrical power or not supplied. A cycle time of the single phases may differ, for example, from a cycle duration of the phase outages. A cycle time is not necessarily to be regarded as uniformly constant. In particular, the clock durations may optionally also be modified depending on currently operating modes or operating parameters (e.g., a desired operating temperature). Also, the clock durations do not need to correspond to a system clock of the cooking appliance, but may also deviate therefrom, in particular amount to a multiple thereof.

A single phase may, in particular, be understood as meaning a period of time during which an electrical power is applied to the heater and heats it. Under a Ausphase analog can be understood in particular a period of time during which no power is applied to the heater. Optionally, the phase-out phase can also be understood as a phase during which a negligibly low heating power is applied to the heater, which can not lead to overheating.

It is an embodiment that the cooking appliance is adapted to start or initiate the reversal of the direction of rotation with the start of the Ausphase. In particular, this also includes an initiation shortly before or after the start of the phaseout. This makes it possible as long as possible to use the duration of the time-out for the reversal of the direction of rotation and thus as long as possible Duration of time during which no heating power has to be delivered and cooled away or transported away. However, a further development can also be that the cooking appliance is set up to reverse the direction of rotation only or exclusively during a Ausphase the heating. In other words, in such an embodiment, a switchover or initiation of the changeover of the direction of rotation reversal during a single phase is prevented. This ensures that a too early switching of the direction of rotation, which leads to overheating due to excessive residual heat of the heater, is avoided.

Another embodiment is that the cooking device is adapted to extend the Ausphase, if the direction of rotation has not yet been reversed. Advantageously, it can thus be prevented that overheating occurs by switching on the Einphase and thus switching on the heater before completing the reversal of the direction of rotation.

It is still an embodiment that the cooking device is adapted to extend the Ausphase, if a reverse direction of rotation associated threshold, in particular speed threshold, has not yet been reached. Thus, the heating can be reactivated, even if e.g. a target speed value has not yet been reached, but the heater at the speed threshold or above is already safe to operate. As a result, a possibly prolonged Ausphase the heater can be kept shorter in order to avoid disturbing a Garbetriebs even further.

The threshold value may be a fixed value or, for example, may be dependent on an operating state of the cooking appliance, e.g. from a heating capacity, a cooking chamber temperature, etc.

It is an embodiment of at least one such threshold value being determined as a function of an operating mode. Thus, for example, a threshold value may be set lower than a threshold value in a mode of operation with high heating power when operating with low heating power (in particular in absolute terms). As a result, overheating can be prevented even more safely. The heating power can, for example, be detected directly as such or be determined as a function of a desired heating level that is set on or by a control unit.

It is also an embodiment that at least one such threshold value is dependent on a cooking chamber temperature. For example, the higher the cooking chamber temperature, the higher the threshold value (in particular in terms of absolute value), in order to prevent overheating particularly reliably. The oven temperature can be determined, for example, as an actual temperature, which is measured via a conventional temperature sensor in the oven, or as a predetermined temperature value setpoint of the control unit.

It is also an embodiment that the cooking appliance has an oven, e.g. a built-in oven or stove is.

The cooking appliance is in particular a Haushaltsgargerät.

The object is also achieved by a method for operating a cooking appliance in which a heater is operated in a clocked manner and in which a hot air blower is driven by a hot air motor, wherein a direction of rotation of the hot air motor is reversed and wherein a reversal of the direction of rotation is performed during a Ausphase the heating becomes. This method gives the same advantages as a cooking device designed in such a preferred manner and can be configured in an analogous manner. The method gives the same advantages as the cooking appliance and can also be configured in an analogous manner.

In particular, the method can be provided for operating such a cooking appliance.

In the following figures, the invention will be described schematically with reference to an embodiment schematically. In this case, the same or equivalent elements may be provided with the same reference numerals for clarity.

1 schematically shows individual components of a cooking appliance according to the invention;

2 shows an exemplary speed curve and a clocking of in and out phases of the cooking appliance according to the invention.

1 shows a cooking appliance 11 with a cooking space 12 , in particular an oven with a furnace room. To heat one in the oven 12 located Garguts has the cooking appliance 11 a hot air blower 13 on.

The hot air blower 13 is located in particular behind a baffle 14 , the back of the cooking chamber 12 is arranged. Hot air can pass through the hot air blower 13 and openings in the baffle 14 depending on the direction of rotation in the oven 12 blown in or out of the oven 12 be sucked out.

The hot air blower 13 has a reversible in its direction of rotation hot air engine 15 in the form of a brushless DC motor. The hot air engine 15 drives an impeller 18 at.

A heater 16 of the hot air blower 13 may in particular as an annular radiator around the impeller 18 be arranged around and so through the wheel 18 heat up flowing air. The heating system 16 is controlled by clocking in and out phases.

The cooking appliance 11 also has a control unit 17 which is adapted to perform general control functions. The control unit 17 is used in particular to control the hot air blower 13 , in particular for generating a clocking of the heating 16 (In particular controlling switching times between the on and off phases of the heating 16 ), for setting a speed D of the hot air motor 15 and thus the impeller 18 and for reversing a direction of rotation of the hot air motor 15 ,

2 shows an exemplary profile of the speed D of the hot air engine 15 over a progressive time t and a clock or clock cycle T of the heating 16 , eg one to the heater 16 applied heating power, current, voltage or similar

Initially, the hot-air engine rotates 15 essentially constant with a first value -De (target speed), the sign indicating the direction of rotation, eg counterclockwise. During this time the heating will be on 16 energized by means of periodic successive phases ap and Einphasen ep, for example, the applied current or the applied voltage.

With the beginning of a certain (here: fourth) Ausphase at the time tap, a reversal of the direction of rotation of the hot air engine 15 initiated. From time tap, the rotational speed D therefore initially continues continuously until the standstill of the hot air blower 13 in terms of magnitude, then again continuously increase in magnitude, but in the opposite direction of rotation (positive sign, eg clockwise). In this case, a linear curve of the rotational speed D is shown here only by way of example and may also have other shapes.

Since the usual duration of the out-phases ap is not sufficient to reverse the direction of rotation and to achieve a sufficiently high speed D to avoid overheating, the extension phase ap is prolonged, as illustrated by the extended extension phase apv. It is a variant that the time-out apv is extended until the speed has returned in terms of amount their normal intended speed De. It is a preferred variant for shortening the phase-out apv that the (extended) phase-out phase apv then ends and changes to a new one-phase ep when the speed reaches or exceeds the magnitude (upper) threshold value Ds, this threshold value Ds having a lower value as the target value De of the rotational speed D. The threshold value Ds represents in particular a rotational speed, from which the hot-air engine 15 and the impeller 18 already turn so fast that overheating can be avoided. The threshold value Ds or -Ds may be a fixed value or, for example, may depend on an operating state of the cooking appliance 11 be, for example, a heating power, a cooking space temperature, etc.

If the direction of rotation is reversed again, switching on the one-phase ep would then take place accordingly when the (lower) threshold value -Ds is reached or exceeded in amount.

Of course, the present invention is not limited to the embodiment shown.

Thus, e.g. in an operating mode with low heating power or with a sufficiently long duration of the phases ap, are waived its extension, if a sufficient reversal of direction can be achieved even within a regular ap phase.

Also, the beginning of the direction reversal can be placed at another time just before or after the outlined tap of the phase apv.

The target speeds De and -De and / or the threshold values Ds and -Ds may be equal in magnitude or may differ depending on the direction of rotation.

LIST OF REFERENCE NUMBERS

11

 Cooking appliance

12

 oven

13

 Heat Guns

14

 baffle wall

15

 Hot-air engine

16

 heater

17

 control unit

18

 Wheel

ap

 off phase

apv

 prolonged Ausphase

D

 rotation speed

de

 first target speed

-De

 second target speed

ds

 upper threshold of the speed

ds

 lower threshold of the speed

ep

 single phase

t

 Time

tap

 Beginning of a phase out

tep

 Beginning of a single phase

T

 clock History

Claims (8)

Cooking appliance ( 11 ), comprising a hot air blower ( 13 ) with a reversible in its direction of rotation hot air engine ( 15 ) and a clocked heating ( 16 ), characterized in that the cooking appliance ( 11 ) is adapted to the direction of rotation during a Ausphase (apv; ap) of the heating ( 16 ) to reverse. Cooking appliance ( 11 ) according to claim 1, characterized in that the cooking appliance ( 11 ) is adapted to begin the reversal of the direction of rotation with the beginning of the Ausphase (tap). Cooking appliance ( 11 ) according to one of the preceding claims, characterized in that the cooking appliance ( 11 ) is arranged to extend the Ausphase (apv; ap), if the direction of rotation has not yet been reversed. Cooking appliance ( 11 ) according to one of the preceding claims, characterized in that the cooking appliance ( 11 ) is adapted to extend the Ausphase (apv; ap), if a reverse direction of rotation associated threshold (-Ds; Ds), in particular speed threshold, has not yet been reached. Cooking appliance ( 11 ) according to claim 4, characterized in that at least one such threshold value (-Ds; Ds) is dependent on a mode of operation. Cooking appliance ( 11 ) according to claim 4 or 5, characterized in that at least one such threshold value (-Ds; Ds) is dependent on a cooking chamber temperature. Cooking appliance ( 11 ) according to one of the preceding claims, characterized in that the cooking appliance ( 11 ) has an oven. Method for operating a cooking appliance ( 11 ), - in which a heating ( 16 ) is operated clocked and - in which a hot air blower ( 13 ) with a hot-air engine ( 15 ) is driven, wherein a direction of rotation of the hot air engine ( 15 ) is reversed, characterized in that - a reversal of the direction of rotation during a Ausphase (apv; ap) of the heating ( 16 ) is carried out.

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