Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B3/00—Ohmic-resistance heating
  • H05B3/68—Heating arrangements specially adapted for cooking plates or analogous hot-plates
  • H05B3/74—Non-metallic plates, e.g. vitroceramic, ceramic or glassceramic hobs, also including power or control circuits
  • H05B3/746—Protection, e.g. overheat cutoff, hot plate indicator

Definitions

• the invention relates to a method for controlling a cooking process in a hob of the type mentioned in claim 1.
• Such a method is known for example from DE 198 56 140 A1.
• the known method controls a cooking process in a cooktop, with a cooktop plate, in particular made of glass ceramic, which, perpendicular to its main directions of expansion, has a material thickness s delimited by a flat upper and lower surface, with at least one cooking zone, which is located below by means of a cooktop in the installed position the cooktop arranged heating device is heated, with an electrical control for controlling the heating power of the heating device and with a first heat sensor unit arranged below the cooktop.
• the known method proposes that a processing unit of the electrical control unit designed as a computing unit compares the output signal of the first heat sensor unit with characteristic data of the measuring arrangement stored in a memory of the electrical control unit and the heating power of the heating device is controlled as a function of a comparison value formed therefrom.
• the known method considers it essential that the first heat sensor unit is designed in such a way that it receives substantially to only the heat radiation radiated from the underside of the hob and that the temperature of the cookware placed on the cooking zone is then deduced from this this is regulated.
• the known arrangement has a cooktop plate, the transmittance of which is at least in the detection range of the first heat sensor unit and at least in its spectral measurement range less than 30%.
• the invention thus presents the problem of specifying a method for controlling a cooking process in a hob, in which the influence of the cookware is taken into account.
• BESTATIGUNGSKOPIE In addition to improved control of a cooking process in a hob, the advantages which can be achieved with the invention consist in particular in the improved accuracy and speed of regulation of the temperature actually present on the cookware.
• the first heat sensor unit for example, to detect only that part of the heat flow which goes down from the cooktop by means of heat conduction, for example by means of a touch temperature sensor.
• the method according to the invention expediently provides that the first and the second heat sensor unit detect the heat radiation as part of the respective heat flow.
• An advantageous development of the method according to the invention provides that, in order to control the cooking process, the emissivity of the cookware base of a cookware placed on the cooking zone is additionally determined by means of a further heat sensor unit. This further improves the accuracy of the control of the cooking process. Furthermore, from the emissivity determined in this way, the temperature of the base of the cookware can be determined automatically with a likewise improved accuracy.
• the invention also presents the problem of specifying a hob for carrying out the method according to the invention.
• the advantages which can be achieved with the invention consist in particular in the improved accuracy and speed of regulation of the temperature actually present on the cookware.
• the type, arrangement and measuring range of the first heat sensor unit can generally be selected within wide suitable limits.
• a particularly simple implementation of the first heat sensor unit and thus the hob according to the invention provides, however, that the first heat sensor unit comprises a touch temperature sensor.
• the measuring range of the first heat sensor unit is limited to the measurement of heat radiation in a first wavelength range and the hob plate in the region of the cooking zone has a transmittance of less at least in the detection range of the first heat sensor unit for heat radiation of the first wavelength range than 20%. This ensures that the first heat sensor unit in the region of the cooking zone essentially only detects heat radiation radiated downwards from the hob plate.
• the transmittance of the hob plate for heat radiation of the first wavelength range is approximately 0% at least in the detection range of the first heat sensor unit. This ensures that the first heat sensor unit in the area of the cooking zone essentially only detects the heat radiation radiated downward from the underside of the hob plate.
• the measuring range of the second heat sensor unit is limited to the measurement of thermal radiation in a second wavelength range, which differs from the first wavelength range, and the hob plate in the area of the cooking zone at least in the detection range of the second heat sensor unit for heat radiation of the second wavelength range has a transmittance of more than 20%. This ensures that the second heat sensor unit in the region of the cooking zone essentially detects the heat radiation radiated downward from the hob plate and the cookware placed thereon.
• the transmittance of the cooktop plate for heat radiation of the second wavelength range is at least about 50% at least in the detection range of the second heat sensor unit.
• the measurement by the second heat sensor unit is further improved due to a larger input signal in the second heat sensor unit.
• a particularly advantageous development of the invention provides that the first and second heat sensor units are designed to measure thermal radiation and at least partially have common components, in particular a common heat sensor. In this way, the number of required heat sensors is reduced, for example.
• Another advantageous development of the invention provides that the material thickness s of the hob plate is reduced at least in the detection area of the second heat sensor unit. As a result, the influence of the heat flow emanating from the hob plate downwards on the heat flow emanating from the hob plate and the cookware placed thereon is reduced in a simple manner.
• the hob plate is designed as a converging lens, at least in the detection area of the second heat sensor unit, starting from the hob plate in the direction of the second heat sensor unit. In this way, the number of components is further reduced.
• at least one deflecting means is arranged in the beam path from the hob plate and / or the cookware base to the first and / or second heat sensor unit. This makes it possible in a structurally simple manner to position the first and / or second heat sensor unit independently of the spatial arrangement of the cooking zone, for example at a cooler location of the hob, in particular in the edge region of the hob.
• the second heat sensor unit has an optical filter arranged in the beam path from the hob plate and / or the cookware base to the second heat sensor unit and made of the same material as the hob plate.
• the suitable materials for cooktop panels, in particular glass ceramics, are cheaper to procure compared to, for example, spectrally selective optical filters to limit the measuring range of the second heat sensor unit.
• a particularly advantageous development of the teaching according to the invention provides that the emissivity of the cookware base of a cookware placed on the cooking zone can be determined by means of the second heat sensor unit. In this way, the accuracy of the control of the cooking process is further improved. Furthermore, from the emissivity determined in this way, the temperature of the base of the cookware can be determined automatically with a likewise improved accuracy. In principle, it is possible to determine the emissivity of the cookware base of a cookware placed on the cooking zone by means of a further heat sensor unit different from the second heat sensor unit. However, the number of components is further reduced by using the second heat sensor unit.
• An advantageous further development of the aforementioned embodiment additionally provides a third heat sensor unit whose measuring range is limited to heat radiation in a third wavelength range that differs from the second wavelength range, the hob plate in the area of the cooking zone at least in the detection range of the third heat sensor unit for heat radiation third wavelength range has a transmittance of more than 20%. This further improves the accuracy of the determination of the emissivity of the cookware base of a cookware placed on the cooking zone and thus the accuracy of the control of the cooking process.
• the cooktop has a coating with a transmittance of approximately 0% in the detection area of the first heat sensor unit on the upper side thereof. This ensures that the first heat sensor unit is independent of the Transmittance of the hob plate in the detection area of the first heat sensor unit essentially only the heat radiation radiated downward from the hob plate is detected.
• the coating has a reflectance of approximately 100%.
• the coating is implemented in a simple manner.
• the coating has an absorption level of approximately 100%. This also ensures that the first heat sensor unit, regardless of the transmittance of the hob plate in the detection area of the first heat sensor unit, essentially detects only the heat radiation radiated downward from the hob plate.
• the invention also has the problem of specifying a system for carrying out the method according to the invention.
• FIG. 1 shows a partial side view of a first exemplary embodiment of a hob according to the invention in a vertical section
• FIG. 2 shows a partial side view of a first exemplary embodiment of a system according to the invention in a vertical section with the hob from FIG. 1
• FIG. 3 shows a diagram showing the transmittance of a hob plate of a hob according to the invention depending on the wavelength of the electromagnetic radiation using the example of a glass ceramic plate
• FIG. 4 shows a partial perspective bottom view of the system from FIG. 2,
• FIG. 5 shows a diagram which shows the qualitative course of an output signal of the two heat sensor units as a function of time
• FIG. 6 shows a partial side view of a second exemplary embodiment of a hob according to the invention
• FIG. 7 is a partial side view of a third embodiment of a hob according to the invention and Figure 8 is a partial side view of a fourth embodiment of a hob according to the invention.
• Fig. 1 shows a first embodiment of a hob according to the invention.
• the cooktop has a cooktop 2 designed as a glass ceramic plate, with a material thickness s limited perpendicular to the main directions of expansion by a flat upper and lower surface 2.1 and 2.2, with at least one cooking zone 4, which is arranged below the cooktop 2 in the installed position of the cooktop 1 is not heatable, with a sensor module 6 arranged below the hob 2, which comprises a first and a second heat sensor unit, only the first heat sensor unit 6.1 being shown in FIG. 1.
• the second heat sensor unit is arranged behind the image plane.
• the first heat sensor unit 6.1 is designed to measure the heat flow coming downward from the hob plate 2 essentially in the area of the cooking zone 4, while the second heat sensor unit is designed to measure the heat plate in the area of the cooking zone 4 essentially from the hob plate 2 and one placed thereon in FIG 1 cookware, not shown, is designed to flow downward, which is explained in more detail below.
• the first and the second heat sensor units 6.1 are each designed as heat radiation sensor units, the measurement range of the first heat sensor unit 6.1 being limited to the measurement of heat radiation in a first wavelength range and the measurement range of the second heat sensor unit being limited to the measurement of heat radiation in a second wavelength range which differs from the first wavelength range.
• the hob plate 2 in the present exemplary embodiment knows that essentially only the heat radiation radiated downwards from the hob plate 2 and essentially the heat radiation radiated downwards from the hob plate 2 and the cookware placed thereon can be detected by the first heat sensor unit for heat radiation of the first wavelength range a transmittance of less than 20% and for
• Heat radiation of the second wavelength range has a transmittance of more than 20%.
• the individual wavelength range can be dimensioned very differently, which is explained in more detail below with reference to FIG. 3.
• a limitation of the measuring range of the first and second heat sensor units 6.1 to a first or second wavelength range can be achieved on the one hand by the respective heat sensor itself having a selective sensitivity.
• an optical filter not shown.
• this filter can be a commercially available spectrally selective filter that only allows heat radiation of the first or second wavelength range to pass through.
• the mentioned embodiments of the filters for limiting the measuring ranges of the respective heat sensor unit are additionally designed as polarization filters.
• a hob plate 2 which is inhomogeneous in terms of the degree of transmission is used, it is sufficient that the hob plate 2 in the area of the cooking zone 4 at least in the detection area of the first heat sensor unit 6.1 as low as possible and as high as possible in the detection area of the second heat sensor unit for thermal radiation according to the above statements.
• This can be done, for example, by exchanging materials in the detection areas of the first and / or the second heat sensor unit 6.1 on the hob 2.
• a suitable material for this is, for example, aluminum oxide.
• the first heat sensor unit 6.1 comprises a touch temperature sensor instead of a heat sensor, namely a heat radiation sensor, and is arranged, for example, in the area of the cooking zone 4 on the underside 2.2 of the hob 2.
• both heat sensor units 6.1 have at least partially common components, for example a common heat sensor.
• the then only heat sensor would have to be movable back and forth in a manner known to the person skilled in the art, for example between two positions, one of which corresponds to the position of the heat sensor of the first heat sensor unit 6.1 and the other to the position of the heat sensor of the second heat sensor unit of the sensor module 6 of the above exemplary embodiment his.
• the first and the second heat sensor unit of the sensor module 6 are in signal transmission connection with an electrical control, also not shown, which has a processing unit and a memory.
• a comparative value is in the processing unit from the output signals of the first and second heat sensor units 6.1 can be generated, which is comparable to previously defined reference values stored in the memory. Depending on this comparison, the heating power of the heating device can be controlled.
• Cookware to determine what is done by determining the comparison value explained above.
• the temperature of the cookware or the cookware base also depends on its emissivity, it is also necessary to specify the emissivity of the cookware or cookware base and store it in the memory or measure it during the cooking process and for processing in the
• the hob according to the invention also has a chopper 8, the construction of which is explained in more detail with reference to FIG. 4, and a light source 10. The determination of the emissivity of the cookware or cookware base placed on the cooking zone 4 is also explained in more detail with reference to the following figure.
• the first exemplary embodiment of the cooktop according to the invention knows a waveguide mirrored on the inside with a coating reflecting the heat radiation, for example a gold layer 12 on.
• a waveguide mirrored on the inside with a coating reflecting the heat radiation for example a gold layer 12 on.
• the use of a sapphire waveguide is conceivable, for example.
• a further possibility of reducing or preventing the influence of interference radiation on the output signals of the two heat sensor units is that for this purpose at least one deflection means, such as in the beam path from the hob plate 2 and / or the cookware base to the first and / or second heat sensor unit 6.1 for example a mirror or the like is arranged. In this way, the sensor module 6 can be completely, at least largely, removed from the influence of the above-mentioned interference radiation. See also Fig. 8.
• Fig. 2 shows the already explained system according to the invention from the hob according to the invention and on the cooking zone 4 of the hob plate 2 cookware 14 in a rotated to Fig. 1 by 90 ° representation.
• the first and the second heat sensor units 6.1 and 6.2 of the sensor module 6 are shown.
• the heating device 16 is shown in FIG. 2, which in a manner known per se in an insulation body 20 is arranged.
• the arrows 18 symbolize the direct and indirect interference radiation from the heating device 16 already explained above.
• the heat radiation emanating from the hob plate 2 or from the bottom of the cookware in the region of the cooking zone 4 becomes in a known manner in the waveguide 12 to the first or second heat sensor unit 6.1, 6.2 forwarded, which is symbolized in FIG. 2 by the arrows 22.
• FIG. 3 shows a diagram that shows the transmittance of a hob according to the invention as a function of the wavelength of the electromagnetic radiation using the example of a glass ceramic plate.
• the measuring ranges of the first and second heat sensor units 6.1, 6.2 are matched to the transmittance of the hob plate 2 used for the hob according to the invention in such a way that the measuring range of the first heat sensor unit 6.1 is limited to a first wavelength range, for which the cooktop 2 has a transmittance of less than 20%, in particular approximately 0% and the measuring range of the second heat sensor unit 6.2 is limited to a second wavelength range, for which the cooktop 2 has a transmittance of more than 20%, in particular at least about 50% , having.
• the first wavelength range is selected at approximately 3 ⁇ m and the second wavelength range at approximately 4 ⁇ m.
• the first wavelength range is selected with approximately more than 5 ⁇ m and the second wavelength range with approximately 2 ⁇ m.
• FIG. 4 shows the chopper 8 from FIG. 1 in detail, looking from below onto the hob according to the invention.
• the chopper 8 has an electric drive 8.1 and one between the two heat sensor units 6.1, 6.2 and the light source 10 and the Waveguide 12 arranged circular plate 8.2.
• a barrier 24, which is only roughly shown in FIG. 4, is arranged between the two heat sensor units 6.1, 6.2 and the light source 10. This prevents interference radiation emanating from the light source 10 from undesirably influencing the heat sensor units 6.1, 6.2.
• the electric drive 8.1 of the chopper 8 is in signal transmission connection with the electrical control of the hob according to the invention and rotates the plate 8.2 in the course of determining the emissivity of the cookware base about an axis of rotation, not shown, running perpendicular to the plate 8.2 and through its center.
• the plate 8.2 has an elongated hole 8.3 in the area that passes over the two heat sensor units 6.1, 6.2 when it rotates, with an elongated hole 8.3 formed at one end of the elongated hole 8.3
• Extension 8.3.1 on and in the area which, when it rotates, essentially sweeps over the two heat sensor units 6.1, 6.2 and the light source 10, a reflector designed as a mirror and arranged on the surface of the plate 8.3 facing these components 6.1, 6.2 and 10 8.4 on. In contrast to the rest of the elongated hole 8.3, the extension 8.3.1 also covers the light source 10 in addition to the two heat sensor units 6.1, 6.2.
• the mode of operation of the chopper 8 is explained in more detail below.
• the hob according to the invention is switched off and cookware 14 is placed on the cooking zone 4.
• the heating device 16 assigned to the cooking zone 4 is switched on by means of an operating element (not shown in the figures), so that the heating device 16 heats up and thus heats the cooking zone 4 and the cookware 14 placed thereon.
• an operating element not shown in the figures
• measurements of the heat radiation radiated essentially downwards in the area of the cooking zone 4 are started by means of the first and second heat sensor units 6.1, 6.2 already explained above, which is illustrated with reference to FIG. 5 is explained.
• 5 is qualitative and applies to the basic temporal profile of the output signal both for the first and for the second heat sensor unit 6.1, 6.2.
• the plate 8.2 of the chopper 8 is in a rotational position, not shown in FIG. 4, in which the plate 8.2 covers both the two heat sensor units 6.1, 6.2 and the light source 10 and thus the two heat sensor units 6.1, 6.2 against the waveguide 12 in Direction of the two heat sensor units 6.1, 6.2 as well as shields against heat radiation emitted by the light source 10 in the direction of the two heat sensor units 6.1, 6.2.
• the plate 8.2 rotates continuously about its axis of rotation up to the rotational position shown in FIG. 4, in which the reflector 8.4 of the plate 8.2 covers the two heat sensor units 6.1, 6.2 and the light source 10.
• the heat radiation emitted by the light source 10 on the reflector 8.4 is deflected almost completely in the direction of the two heat sensor units 6.1, 6.2 and received by them in the corresponding first and second wavelength ranges as an input signal, see region b in FIG. 5 ,
• the plate 8.2 continues to rotate and the two heat sensor units 6.1, 6.2 and
• the light source 10 is again covered by the plate 8.2, namely in the area of the plate 8.2 arranged between the reflector 8.4 and the elongated hole 8.3, see FIGS. 4 and 5, area c, so that for this rotational position of the plate 8.2 the explanations of the area a from FIG. 5 apply analogously.
• the plate 8.2 continues to rotate until the elongated hole 8.3 arranged in the plate 8.2 releases the beam path between the hob plate 2 or the hob plate 2 and the cookware base of the cookware 14 in the region of the waveguide 12 and the two heat sensor units 6.1, 6.2.
• the heat radiation radiated downward in the area of the cooking zone 4 from the hob plate 2 or from the hob plate 2 and the cookware 14 placed thereon reaches the two heat sensor units 6.1, 6.2 and is received by them in accordance with the first and second wavelength ranges as an input signal, which leads to an increase in the output signal of each heat sensor unit 6.1, 6.2 up to the qualitative value labeled d in FIG. 5.
• the value of the output signal of the first heat sensor unit 6.1 is somewhat lower than the value of the output signal of the second heat sensor unit 6.2, since the first heat sensor unit 6.1 essentially receives the heat radiation radiated downwards from the hob plate 2, while the second heat sensor unit 6.2 essentially receives the heat radiation radiated downwards from the hob plate 2 and the cookware 14 placed thereon, in each case in the detection range of the respective heat sensor unit 6.1, 6.2.
• the plate 8.2 continues to rotate until the other end of the elongated hole 8.3 with the extension 8.3.1 is reached. In this rotational position of the plate 8.2, the beam path between the light source 10 and the waveguide 12 is also released through the plate 8.2, so that the Heat radiation emitted by the light source 10 is radiated through the waveguide 12 onto the hob plate 2 or the hob plate 2 and the cookware base and is at least partially reflected by them in the direction of the two heat sensor units 6.1, 6.2, see FIG. 5, area e.
• the values of the resulting output signals of the two heat sensor units 6.1, 6.2 are therefore somewhat larger than in the aforementioned range d.
• the plate 8.2 rotates further into an area of the plate 8.2 which, analogous to the areas a and c already explained, the two heat sensor units 6.1, 6.2 against the plate 2 or the hob 2 and the cookware 14 placed on the cooking zone 4 shields downward radiated heat radiation, see FIG. 5, area f.
• the effect of the barrier 24 against interference radiation emitted by the light source 10 has already been explained above.
• the plate 8.2 continues to rotate and the measuring cycle explained above begins again.
• Heat sensor units 6.1, 6.2 continuously or at predetermined time intervals, a comparison value is formed and compared in a manner known per se with previously defined reference values and stored in the memory of the electrical control.
• a comparison value is formed and compared in a manner known per se with previously defined reference values and stored in the memory of the electrical control.
• the processing unit determine the emissivity of the cookware base by comparing the output signals of the two heat sensor units 6.1, 6.2 in area b from FIG.
• the heating device 16 for determining the emissivity of the cookware base and thus its actually undesirable one
• the heating device 16 is briefly switched off.
• the measuring range of the third heat sensor unit is limited to heat radiation in a third wavelength range, which differs from the second wavelength range, the hob plate 2 in the area of the cooking zone 4 at least in the detection range of the third heat sensor unit for heat radiation of the third wavelength range a transmittance of more than Has 20%.
• the temperature of the cookware base and thus the value of the heat radiation emitted by the cookware base depends not only on its wavelength range but also on the emissivity of the cookware base, it is possible to use a ratio pyrometer measurement known per se using the second and third heat sensor units 6.2 , and the increase in the value of the heat radiation determined in this way over a predetermined wavelength range even without determining the emissivity of the cookware base, its temperature and thus regulating the heating output.
• a particularly simple alternative to the abovementioned possibilities of including the influence of the emissivity of the cookware base in the regulation of the heating output is that on the cookware base at least in the area with the cookware 14 placed on the cooking zone 4 with the detection range of the second one
• Heat sensor unit 6.2 overlaps, a coating with a predetermined emissivity and stored in the memory of the electrical control is applied.
• a further alternative to the first exemplary embodiment provides that the cooktop 2 has a coating with a transmittance of approximately 0% in the detection area of the first heat sensor unit 6.1 on its upper side.
• a Realization possibility is that the coating has a reflectance of about 100%.
• the hob plate 2 it is also conceivable for the hob plate 2 to have a coating with an absorption level of approximately 100% on the upper side in the detection area of the first heat sensor unit 6.1.
• a collecting lens 26 is arranged in the detection areas of the two heat sensor units 6.1, 6.2, starting from the hob plate 2 in the direction of the two heat sensor units 6.1, 6.2, due to the high temperature resistance, for example made of barium fluoride or aluminum oxide, by means of which the plate from the hob is arranged 2 and the cookware 14 placed on the cooking zone 4 and downwardly radiated heat radiation is focused on the first and / or second heat sensor unit 6.1, 6.2 in a manner known per se.
• the high temperature resistance for example made of barium fluoride or aluminum oxide
• the material thickness s of the hob plate 2 is additionally reduced in the detection range of the second heat sensor unit 6.2.
• the hob plate 2 is at least in the
• FIG. 8 shows a fourth exemplary embodiment of the teaching according to the invention, in which the sensor module 6 is arranged instead of below the cooking zone 4 in the edge region of the hob according to the invention.
• the use of a waveguide 12 is dispensed with, since the interference radiation due to the deflecting means 28 arranged in the beam path between the hob plate 2 or the cookware 14 and the two heat sensor units 6.1, 6.2 for deflecting the downward radiated heat radiation on the two heat sensor units 6.1, 6.2 is directed past, which is symbolized in FIG. 8 by a dashed arrow 30.
• the difference is the heat radiation radiated downwards from the hob 2 or from the hob plate 2 and the cookware 14 placed on the cooking zone 4 directed in the direction of the two heat sensor units 6.1, 6.2 in a manner known to those skilled in the art, which is symbolized in FIG. 8 by arrows 32 is.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Electric Stoves And Ranges (AREA)
• Cookers (AREA)
• Control Of High-Frequency Heating Circuits (AREA)

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• 2004
  • 2004-01-15 DE DE102004002058A patent/DE102004002058B3/de not_active Expired - Fee Related
• 2005
  • 2005-01-10 WO PCT/EP2005/000122 patent/WO2005069693A1/fr not_active Ceased
  • 2005-01-10 AT AT05700769T patent/ATE367074T1/de not_active IP Right Cessation
  • 2005-01-10 DE DE502005001014T patent/DE502005001014D1/de not_active Expired - Lifetime
  • 2005-01-10 EP EP05700769A patent/EP1704754B1/fr not_active Expired - Lifetime

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