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
  • H05B6/00—Heating by electric, magnetic or electromagnetic fields
  • H05B6/64—Heating using microwaves
  • H05B6/80—Apparatus for specific applications
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
  • G01J5/02—Constructional details
  • G01J5/06—Arrangements for eliminating effects of disturbing radiation; Arrangements for compensating changes in sensitivity
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
  • G01J5/0044—Furnaces, ovens, kilns
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
  • G01J5/02—Constructional details
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
  • G01J5/02—Constructional details
  • G01J5/0215—Compact construction
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
  • G01J5/02—Constructional details
  • G01J5/04—Casings
  • G01J5/041—Mountings in enclosures or in a particular environment
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
  • G01J5/02—Constructional details
  • G01J5/04—Casings
  • G01J5/041—Mountings in enclosures or in a particular environment
  • G01J5/045—Sealings; Vacuum enclosures; Encapsulated packages; Wafer bonding structures; Getter arrangements
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
  • G01J5/02—Constructional details
  • G01J5/04—Casings
  • G01J5/046—Materials; Selection of thermal materials
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
  • G01J5/02—Constructional details
  • G01J5/08—Optical arrangements
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
  • G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
  • G01J5/02—Constructional details
  • G01J5/08—Optical arrangements
  • G01J5/0806—Focusing or collimating elements, e.g. lenses or concave mirrors
• • 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
  • H05B6/00—Heating by electric, magnetic or electromagnetic fields
  • H05B6/64—Heating using microwaves
  • H05B6/6447—Method of operation or details of the microwave heating apparatus related to the use of detectors or sensors

Definitions

• the invention relates to electric cooking ovens comprising, in an envelope, a heating enclosure, the vault of which has a sighting opening behind which is mounted a device for measuring infrared radiation intended to determine the temperature of a body. introduced into the enclosure and comprising an infrared sensor mounted on a support and having a housing containing an element sensitive to infrared radiation located opposite a capture window.
• the infrared radiation sensor makes it possible to measure without contact the temperature of the body, food or other, which is introduced into the enclosure.
• the infrared radiation measurement device is disturbed in particular by the thermal drift due to significant variations in the ambient temperature of the enclosure and that prevailing between the envelope and the enclosure, but also by the radius.
• parasitic infrared noise due to the heating of the various neighboring parts constituting the oven and in particular by the heating of the measuring device itself.
• electronic circuits which include a temperature sensor intended to measure by contact the temperature of the housing of the radiation sensor in order to deliver a correction signal proportional to the thermal drift of the radiation sensor .
• the temperature sensor is enclosed in the housing of the infrared sensor and is capable of delivering a correction signal which will be analyzed by an external processing circuit.
• these additional temperature sensors only perform a point measurement which is not identical at all points of the housing, the housing itself creating a shadow of parasitic heat radiation.
• the invention therefore aims to overcome this incon ⁇ venient.
• said device for measuring infrared radiation comprises means for homogenizing the temperature of the sensor housing and of the support.
• the homogenization means are formed by a thermal part secured to the support and surrounding the housing while providing the collection window.
• the thermal part takes into account in particular the temperature of the support and standardizes the temperature of the housing, which makes it possible to obtain at all times an identical temperature, at all points. Thanks to these homogenization means, the compensation for thermal drift is obtained in a global manner and takes account of the main components of the device for measuring the infrared ray.
• the support and the sensor are offset laterally with respect to the sighting opening and the support comprises a frame for receiving a reflection mirror of the infrared ray coming from the enclosure to the sensor.
• the support makes it possible to position the sensor specifically with respect to the mirror at a distance from the sighting opening, therefore in a location which is not directly subjected to hot air and to dirt which passes through the sighting opening.
• the frame integral with the support also contributes to the homogenization of the temperature at the level of the housing, because it takes into account the temperature of the mirror subjected to infrared radiation.
• FIG. 1 is a schematic vertical section of an oven comprising a device for measuring infrared radiation according to a first embodiment of the invention and also illustrated in section;
• FIG. 2 is a view similar to Figure 1 but illustrating a second embodiment of the measuring device according to the invention
• FIG. 3 is an enlarged sectional view of the measuring device illustrated in FIG. 2.
• the electric cooking oven comprises an envelope 1 surrounding a heating enclosure 2 heated for example by an armored electrical resistance R arranged on the roof 3 of the enclosure.
• the enclosure can also be heated by microwave and comprise, as is known per se, a magnetron M illustrated in broken lines in these same Figures 1 and 2.
• This electric oven is equipped with a device 5 for measuring infrared radiation with a view to determining the temperature of a body 6 introduced into the enclosure, this body possibly being a food or a liquid such as a soup.
• the vault 3 of the enclosure has a sighting opening 4 behind which is mounted the device 5 and in particular an infrared sensor 7 mounted on a support 8 and arranged between said envelope 1 and said enclosure 2.
• the viewing opening 4 is preferably arranged in the central region of the vault 3 and thus allows precise measurement of the body 6 which generally extends to the center of the enclosure. This is all the more true in a microwave oven where the body 6 is generally placed on a rotary plate P arranged in the central region of the enclosure.
• FIGS. 1 and 2 we have diagrammed in FIGS. 1 and 2 the infrared radiation by a conical envelope rising from the body 6 towards the sensor 7.
• the infrared sensor 7 is of the thermopile type, for example, and comprises, in a manner known per se, a housing 9 enclosing a sensitive element (not shown) which is situated opposite a collection window 11 formed in the housing 9 and which is connected to the internal wall of the housing by a series of connections (not shown) having so-called hot welds (integral with the sensitive element) and so-called cold welds (integral with the internal wall of the housing).
• This type of sensor provides an output signal proportional to the intensity of the radiation and therefore proportional to the temperature difference between hot and cold welds.
• this type of sensor also comprises in the housing 9 one or more temperature sensors (NTC diode or other) (not shown) which are intended to measure the temperature by contact with the housing.
• NTC diode or other temperature sensors
• the device 5 for measuring the infrared radiation comprises means for homogenizing the temperature of the housing 9 of the sensor 7 and of the support 8.
• the homogenization means are formed by a thermal part 13 secured to the support 8 and by turning the housing 9 while providing the collection window 11.
• this thermal part 13 can advantageously be formed in one piece with the support 8 and be made of a material whose emissivity and resistance are very low.
• a material can for example be: aluminum, polished or anodized; gold; money; iron, polished or oxidized; steel; the bronze.
• the thermal part 13 is molded with the support 8 and forms a chamber, the in ⁇ ferior wall 8 ′ of which is thermally coupled to the vault 3 and has an opening 12 coaxial with the opening 4, and the upper wall of which contains the housing 9 of the sensor 7 located to the right of the viewing opening 4.
• the housing 9 of the sensor 7 illustrated in the figures has the general shape of a cap having an edge 9 ′, and the face opposite to the window 11 has lugs 14 for electrical connection on which we just take the sensor output signal.
• the thermal part 13 has a tubular housing 15 for receiving the housing 9, the end openings 16 and 17 of which are adapted to allow the collection region 11 ′ and the tabs 14 to pass respectively.
• the opening 17 is closed by a cover 18 having passage holes 19 for the tabs 14 and made of a material identical to the thermal part 13. Consequently, the sensor 7 is enclosed in the housing 15 and its housing is put at a uniform temperature.
• the support 8 comprises a tubular guide 20 which enters the heating enclosure 2.
• This guide carries at its protruding end 21 a filter 22 transparent to the infrared ray, for example made of silicon or germanium.
• the filter 22 has a wide spectral band which extends in a range from 5 ⁇ m to 14 ⁇ m (microns).
• the filter 22 the sensor 7 and in particular the collection window, they are protected against food projections which may be in gaseous, liquid or solid form.
• Another function fulfilled by the filter 22 is the thermal insulation of the sensor 7 against the hot air of the enclosure. Indeed, this filter sealingly closing the guide 20, the chamber formed by the support 8 is therefore also sealed, which provides a calm and thermal iso ⁇ atmosphere suitable for promoting the measurement of infrared radiation.
• the invention provides, so as to avoid the deposition of condensation droplets in the sighting region through the filter 22, to mount this filter according to an inclined plane on the axis of the guide 20 thus constituting a slope and a low zone towards which the condensation droplets flow.
• the sup ⁇ port 8 comprises a frame 24 for receiving a mirror 25 for reflecting infrared radiation coming from the opening 4 by the guide 20.
• the mirror 25 is preferably of parabolic shape, the focus of which is substantially at the level of the sensitive element contained in the housing 9 of the sensor 7.
• the mirror 25 is made of a highly polished metal, aluminum, stainless steel which has a very high reflection coefficient and a low emissivity coefficient.
• the special embodiment of the support 8 in a single body forming the thermal part 13, the tubular guide 20 and the frame 24, makes it possible to obtain perfect homogenization of the temperature at the level of the housing 9 of the sensor 7 because this single body takes also take into account the temperature of the mirror 25 and of the filter 22 which are closely associated with it. Indeed, the mirror 25 constituting one of the walls of the sealed box thus formed transmits its temperature by conduction to the support 8.
• the manufacture of such a measuring device is particularly simple and economical since the body can be produced by molding, and the mirror 25, the filter 22 and the sensor 7 are subsequently mounted so as not to damage them.
• a device for measuring infrared radiation which can be adapted to all ovens whether they are electric resistance, microwave or combined heating, since this device is presented in the form of a watertight box which it suffices to attach to a wall in an appropriate place to take the temperature measurement of the heated food.
• the invention further provides that the sealed box is itself enclosed in a casing 26 sealed against microwave radiation, the guide tubular 20 and a tube 27 for passing the electrical connection wires with the lugs 14 of the sensor 7 having suitable dimensions • forming a wave trap.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Spectroscopy & Molecular Physics (AREA)
• Electromagnetism (AREA)
• Electric Ovens (AREA)
• Radiation Pyrometers (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=9464376

Family Applications (1)

Country Status (5)

Families Citing this family (3)

Family Cites Families (5)

• 1994
  • 1994-06-17 FR FR9407492A patent/FR2721380B1/fr not_active Expired - Fee Related
• 1995
  • 1995-06-16 JP JP8501745A patent/JPH10505661A/ja active Pending
  • 1995-06-16 EP EP95923394A patent/EP0945048A1/de not_active Withdrawn
  • 1995-06-16 KR KR1019960707351A patent/KR970704323A/ko active IP Right Grant
  • 1995-06-16 WO PCT/FR1995/000793 patent/WO1995035643A1/fr not_active Application Discontinuation

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events