Center temperature detector and combined cooking utensil with center temperature detector

Abstract

The invention discloses a center temperature detector and a combined cooking utensil with the center temperature detector. The invention relates to a center temperature detector (28) for a combination cooking appliance (10). The center temperature detector (28) comprises a measuring portion (32) and a handle portion (30). Furthermore, a contact tube (50) is provided, in which the cable (36) is guided. The cable (36) has an unsheathed region (88) in the handle part (30), in which unsheathed region (88) the contact tube (50) forms a contact point (90) together with the cable (36), the contact point (90) having a distance d1 to the handle-side end (52), which distance d1 corresponds to an electrical length of the microwave radiation in the handle part (30), the electrical length is shorter than or equal to a quarter of the wavelength of the microwave radiation used in the combination cooking appliance (10). The invention also relates to a combination cooking appliance (10) comprising a central temperature detector (28).

Description

Technical Field

[0001] The present invention relates to a core temperature detector with a microwave catcher and a cooking utensil with the core temperature detector. Background Art

[0002] In professional kitchens or canteen kitchens, combination cooking appliances are used, which can cook cooking products in different ways in the cooking chamber of the combination cooking appliance. In addition to the classic cooking methods using hot air and / or steam, modern combination cooking appliances usually use microwave radiation. To cook the cooking products, the energy of microwave radiation can be used alone or in combination with the aforementioned methods. A magnetron or a semiconductor component can be used as a microwave source to feed microwaves into the cooking chamber.

[0003] In order to achieve the best possible results when cooking culinary products, it is advantageous to monitor the cooking process as accurately as possible in order to modify certain cooking parameters, such as temperature, air humidity and / or cooking time, if necessary.

[0004] In modern cooking appliances, core temperature detectors or the like are used for this purpose. The core temperature detector generally comprises a measuring rod equipped with a temperature sensor, which is inserted into the cooking product before the start of the cooking process. During the cooking process, the temperature sensor measures the core temperature in the center of the cooking product and transmits this core temperature to an evaluation unit of the cooking appliance. The measured core temperature makes it possible to determine the degree of cooking of the cooking product, so that the cooking process can be adjusted based on this information to achieve the desired cooking result.

[0005] In microwave operation, the use of a core temperature detector results in the problem that the measuring rod acts as an antenna for the microwaves fed in. This results in an undesired current in the core temperature detector, which causes a temperature increase in the core temperature detector. This can cause the core temperature detector to overheat, which can damage the core temperature detector. This can occur in particular when the core temperature detector is in the park position, i.e. not inserted into the cooking product.

[0006] If the core temperature detector is inserted into the cooking product, the cooking product may be heated above average in the region of the measuring rod. The measured temperature may also be falsified by an undesired heating of the core temperature detector, in particular the temperature sensor. Summary of the invention

[0007] In this respect, it is an object of the present invention to provide a device for preventing damage to the core temperature detector, undesired heating of the cooking product and erroneous measurement results when microwave operation is switched on in a combination cooking appliance.

[0008] According to the invention, this object is achieved by a core temperature detector of a combined cooking appliance for cooking a cooking product, the core temperature detector comprising a measuring part and a handle part. In addition, a contact tube is provided, which extends at least partially into the handle part and has a handle-side end facing the handle part. The cable extending from the handle part into the measuring part is guided in the contact tube. The cable has a sheath-free area in the handle part, in which the contact tube forms a contact point together with the cable. The contact point has a distance to the handle-side end that corresponds to the electrical length of the microwave radiation in the handle part, which electrical length is shorter than or equal to one quarter of the wavelength of the microwave radiation used in the combined cooking appliance.

[0009] This ensures that during microwave operation of the combined cooking appliance, the handle-side end of the contact tube is located in the minimum of the electromagnetic field (hereinafter referred to as the E-field) generated by the microwave radiation, i.e. at a location in the electromagnetic field where the field strength has a local or global minimum. This reduces the current flow in the handle-side end at this location, thereby reducing the total energy input into the core temperature detector. The lower energy input in turn leads to less heating of the core temperature detector, in particular the handle part, as a result of which the durability of the handle is extended in a simple manner. Since the service life of the core temperature detector is largely determined by the durability of the handle part, the core temperature detector as a whole has an improved service life.

[0010] The contact tube is a tubular element having the shape of an elongated hollow cylinder, so that the cable can be received and guided therein. In particular, the contact tube is a cylinder, ie it has a circular cross section.

[0011] The handle-side end is understood to mean the end of the contact tube facing the handle part, ie away from the measuring part. Thus, as seen from the handle-side end, the contact point is arranged in the direction of the measuring part.

[0012] "Measuring portion" refers to a region which, when inserted, is used to measure the temperature inside the cooking product. For example, at least one temperature sensor may be arranged in the measuring portion for this purpose. For this purpose, the measuring portion does not have to be fully inserted into the cooking product. The measuring portion is also referred to as a measuring rod.

[0013] The term "handle portion" refers to an area of ​​the core temperature detector where a user can hold the core temperature detector. To this end, the handle portion can, for example, have a shape that is ergonomically suitable for a hand so that the core temperature detector can be easily manipulated in the cooking chamber.

[0014] The wavelength refers specifically to the wavelength in a vacuum (or approximately in air).

[0015] Electrical length is understood to be the distance an electromagnetic wave travels in a propagation medium, for example in the handle section and / or in the measuring section. This is particularly the case when the field lines are completely within the material, such as in a coaxial structure, in particular between a braided shield and a contact tube.

[0016] Due to the dielectric properties of the materials arranged in the two parts, the electrical length can be different from the length or distance that an electromagnetic wave would travel in a vacuum (simultaneously), which is also called the mechanical length. In other words, depending on the dielectric constant and magnetic permeability (if applicable) of the propagation medium, the electrical length is less than or at most equal to the distance in a vacuum. Mathematically, the relationship can be expressed as follows:

[0017]

[0018] l el is the electrical length, l mech is the mechanical length, μμ r is the relative magnetic permeability, ε r is the relative permittivity, which corresponds to the dielectric. For common materials, the relative permeability is μμ r and relative dielectric constant ε r The product of is greater than 1. In a vacuum, the product is exactly 1, while in air it is approximately 1.

[0019] In particular, the volume (field strength) weighted relative permittivity ε r and volume (field strength) weighted relative permeability μμ r Can be used for the handle part of the core temperature detector. The field lines are only partially present in the handle or measuring part, because the other part is present in the air.

[0020] The handle portion (i.e., all materials arranged therein) corresponds to the electrical length of the microwave radiation in the handle portion, which means that the electromagnetic waves (i.e., microwaves) of the microwave radiation in the handle portion have an electrical length corresponding to at least one-quarter of the wavelength of the microwave radiation. Depending on the material in the handle portion, the distance between the contact point and the handle side end is shorter than the electrical length. The greater the relative permeability number of the material used in the handle portion, the shorter the distance can be, thereby still ensuring that the electrical length of the microwave radiation in the handle portion is less than one-quarter of the wavelength of the microwave radiation (in a vacuum). As described above, this is due to the influence of permeability and dielectric constant.

[0021] In this regard, electrical length can be understood as the distance traveled in a vacuum with a velocity factor. The velocity factor arises from the fact that electromagnetic waves (i.e., microwaves) propagate in a propagation medium with a different dielectric constant (and magnetic permeability) than a vacuum, such as in the material in the handle portion. The handle portion represents a dielectric for electromagnetic radiation entering it. This physical relationship is represented by the velocity factor, which depends on the propagation medium and is "1" in the case of a vacuum.

[0022] Therefore, assuming that the material in the handle part (propagation medium), in particular the material inside the groove, is different from the material in the cooking chamber, such as the material of the handle, contact tube, cable or other components in the handle part, the distance between the contact point and the side end of the handle can be shorter, i.e. shorter due to the speed factor.

[0023] In this regard, the following relationships generally apply:

[0024]

[0025] λ corresponds to the wavelength of the microwave radiation used in the cooking chamber (in a vacuum), d distance F is the distance between the contact point and the handle side end, handle section is the speed factor of the handle part, where the speed factor can be expressed as express.

[0026] In order to ensure a particularly low energy input into the handle part, it is preferred that the electrical length is at least 0.1 cm shorter than a quarter of the wavelength of the microwave radiation used in the combination cooking appliance. Particularly preferably, the electrical length is at least 0.5 cm shorter than a quarter of the wavelength of the microwave radiation used in the combination cooking appliance. Particularly preferably, the electrical length is at least 1.5 cm shorter than a quarter of the wavelength of the microwave radiation used in the combination cooking appliance.

[0027] According to a first aspect of the invention, provision is made as follows: the core temperature detector is provided with a microwave catcher having a pot-shaped catcher portion with a catcher opening aligned with the measuring portion and a bottom provided with a central channel in the direction of the handle portion. The contact tube extends through the central channel.

[0028] "Pot-shaped catcher portion" refers to a region of the microwave catcher that captures electromagnetic waves in the microwave range. To this end, the pot-shaped catcher portion has a geometric depth as measured from the bottom to the opening that is specific to at least one electrical length of the electromagnetic radiation used in the cooking chamber to capture the electromagnetic radiation in the catcher portion.

[0029] A microwave catcher refers to a quarter wave catcher. A quarter wave catcher is a component that prevents microwave radiation from passing through the component. Basically, a microwave catcher can be designed as desired, as long as it has a geometric depth corresponding to an electrical length of approximately one quarter of the wavelength of the microwave radiation used in the cooking chamber. A quarter wave catcher can also include a dielectric with a geometric depth shorter than one quarter of the wavelength, wherein the quarter wave catcher still has an electrical length corresponding to one quarter of the wavelength.

[0030] In addition, the microwave catcher also works in conjunction with the arrangement of the contact point and the handle side end, because the microwave catcher generally reduces the microwave radiation entering the handle part, and the distance between the contact point and the handle side end further reduces the energy input of the remaining microwave radiation into the handle part.

[0031] In particular, the contact tube is in contact with the bottom at the central passage, wherein the contact tube is preferably laser welded to the bottom at the central passage. This is a particularly efficient manufacturing method for the microwave trap.

[0032] According to a further aspect, the contact tube contacts the shield of the cable in an electrically conductive manner at the contact point. Thus, according to this aspect, the contact tube is made of an electrically conductive material, preferably a metallic material. Due to the conductive properties, the contact tube can absorb current and transmit the current to the unsheathed area of ​​the cable via the contact point.

[0033] Preferably, the shield is a braided shield. Braided shielding is a proven method of protecting the interior of a cable from electromagnetic interference.

[0034] In a further embodiment of the invention, the handle-side end of the contact tube is arranged in an insulating region of the cable in which the shield is surrounded by the outer cable sheath.

[0035] In this respect, the handle-side end forms a transition from the contact tube to the outer wire sheath of the cable. In particular, the handle-side end is crimped onto the outer wire sheath of the cable, and the ends of the cable and the contact tube are thus firmly connected to each other. On the one hand, the arrangement of the handle-side end on the outer wire sheath facilitates the introduction of the current generated along the contact tube into the shielding element not via any point, but only into the sheath-free area, whereby the current introduced into the cable is limited. On the other hand, the penetration of liquids and air moisture is prevented.

[0036] The outer wire sheath is preferably made of a non-conductive material such as PTFE.

[0037] A further aspect of the invention provides that a counterpressure element is arranged in the jacket-free region below the shield, which counterpressure element is designed to exert a radially outwardly directed force on the shield, so that the shield is pressed outwardly against the contact tube.

[0038] The counter-pressure element may be a sleeve etc. The only requirement is that the counter-pressure element has the shape of a hollow cylinder so that it can accommodate the interior of the cable.

[0039] Preferably, the counterpressure element has a diameter which is equal to or greater than the diameter of the shield, so that when the shield is placed on the counterpressure element, the counterpressure element is pressed radially outwards by an amount which is equal to or greater than the diameter of the counterpressure element.

[0040] Alternatively, a pressure element can be arranged in the jacket-free region above the shield, via which a contact point is formed which (indirectly) connects the cable, in particular its shield, to the contact tube. In other words, the contact tube forms an (indirect) contact point with the cable, i.e., in the jacket-free region.

[0041] The pressure element may be crimped to the shield and rolled with the contact tube.In order to provide a counter pressure for rolling on the contact tube, the pressure element may comprise a portion having a larger diameter than the rest of the pressure element.

[0042] In this respect, the contact tube is connected indirectly to the cable via the pressure element.

[0043] In principle, the contact point establishes an electrical contact between the cable and the contact tube. The electrical contact can be indirect, i.e. via a pressure element, or direct, provided that the contact tube is in direct contact with a part of the cable, such as the shielding of the cable. A counter-pressure element can then be provided, which is arranged below the shielding.

[0044] However, the pressure element can also constitute a counter-pressure element for the contact tube. This is because the pressure element is applied to the cable, in particular to the shielding of the cable, but when the contact tube is rolled, the pressure element acts as a counter-pressure element for the contact tube.

[0045] Another embodiment of the invention relates to the contact tube substantially completely contacting the shield at the contact point along the circumference of the shield, so that the contact point forms a continuous contact ring. Alternatively, the contact tube can substantially completely contact the pressure element at the contact point along the circumference of the pressure element, so that the contact point forms a continuous contact ring.

[0046] This ensures a particularly good contact. In addition, the continuous contact in the form of a contact ring provides a particularly stable connection between the contact tube and the shield or the pressure element.

[0047] According to a further aspect of the invention, the contact point is formed by a radially inwardly directed projection of the contact tube, wherein the projection is produced in particular by rolling the contact tube onto the cable.

[0048] An inwardly directed projection is a recess directed radially inwardly along the circumference of the contact tube, which recess contacts the shield at least with its apex and thus forms an electrically conductive contact with the shield. The projection is easy to manufacture and thus represents a simple design for establishing contact between the contact tube and the shield. Furthermore, the projection reduces the diameter of the contact tube and presses on the shield, so that the shield and therefore also the cable are firmly held against sliding on the projection.

[0049] A further aspect of the invention provides that the contact point is arranged at a minimum distance from the bottom.

[0050] According to the invention, the distance between the contact point and the handle-side end corresponds to a distance corresponding to the electrical length of the microwave radiation in the handle portion, which is equal to or less than one quarter of the wavelength of the microwave radiation used in the combination cooking appliance. This condition can be achieved particularly easily by placing the contact point as close as possible to the bottom of the microwave catcher. The term minimum distance therefore refers to the technically smallest possible distance at which the bottom can be spaced apart from the contact point without the bottom being deformed by the introduction of the contact point between the contact tube and the shield, which would have a negative impact on the function of the microwave catcher.

[0051] For example, the distance is 0.1 mm to 4 mm, preferably 0.1 mm to 2 mm, particularly preferably 0.1 mm to 1 mm.

[0052] According to a further aspect of the invention, the catcher opening has a distance to the handle-side end corresponding to an electrical length of the microwave radiation in the handle portion which is shorter than or equal to one quarter of the wavelength of the microwave radiation used in the combination cooking appliance.

[0053] The distance between the catch opening and the handle-side end is measured from the center of the catch opening to the center of the handle-side end of the contact tube, the two centers having a common rotation axis extending from the handle portion into the measuring portion.

[0054] Due to the selected distance between the catcher opening and the handle-side end, the transition from the contact tube to the outer wire sheath of the cable is also located at a local or global minimum in the electric field in microwave operation of the cooking appliance. As a result, a lower field strength couples to the transition point and the sheath current is reduced. This has the advantage that less heat is generated at the handle-side end, which prolongs the durability of the core temperature detector.

[0055] Furthermore, the invention relates to a combined cooking appliance for cooking a cooking product, the combined cooking appliance comprising a cooking chamber, a microwave generator and a control unit, the control unit communicating with a core temperature detector according to any of the preceding aspects, the core temperature detector being arranged in the cooking chamber. The combined cooking appliance is a cooking appliance for cooking a cooking product which, in addition to using microwave radiation, can also cook the cooking product with the aid of steam and / or hot air. Such a cooking appliance allows a combination of different cooking methods, which can be used individually or in combination.

[0056] Due to the use of the core temperature detector according to the above aspects, the combined cooking utensil according to the present invention can use the core temperature detector during microwave operation without overheating the handle portion and / or the measuring portion. Since the measuring portion is not locally heated, more accurate temperature sensing is possible, which enables the cooking utensil to monitor the cooking process more accurately. This also makes it possible to control the cooking process more accurately and achieve better cooking results. In contrast, the reduced heating of the handle portion enables a longer durability of the core temperature detector. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Further features and advantages of the present invention will become apparent from the following description and accompanying drawings, with reference to and in which:

[0058] - Figure 1 shows a schematic representation of a combined cooking appliance according to the invention with a core temperature detector according to the invention;

[0059] - Figure 2 Shown according to Figure 1 A schematic cross-sectional view of a core temperature detector of the present invention;

[0060] - Figure 3 Shown according to Figure 1 A schematic cross-sectional view of a handle portion of a core temperature detector of the present invention;

[0061] - Figure 4 Shown is the Figure 1 A schematic representation of the measuring side end of the cable of the core temperature detector of the present invention;

[0062] - Figure 5 Shown according to Figure 1 A schematic cross-sectional view of a cable guide in a handle of a core temperature detector of the present invention;

[0063] - Fig. 6A Shown according to Figure 1 A schematic cross-sectional view of a cable guide with a counter-pressure element in a handle of a core temperature detector of the present invention;

[0064] - Figure 6B Shown according to Figure 1 A schematic cross-sectional view of a cable guide having a pressure element designed as a covering sleeve in a handle of a core temperature detector of the present invention;

[0065] - Figure 7 shows the Figure 1 A simulation model for simulating the electromagnetic load of the core temperature detector of the present invention;

[0066] - Figure 8 shows the E field along the central temperature detector not according to the present invention, according to Figure 7 Simulation graphics of the simulation model;

[0067] - Fig. 9 Shows Figure 8 A diagram of a simulated graph;

[0068] - Fig.10 The E field along the central temperature detector according to the present invention is shown according to Figure 7 A simulation graph of a simulation model; and

[0069] - Fig.11 Shows Fig.10 Figure 4 shows a simulated graphic of the . DETAILED DESCRIPTION

[0070] Figure 1 A combination cooking appliance 10 according to the invention having a cooking chamber 12 is schematically shown.

[0071] In addition, a heating device 14 , a steam generator 16 , and a microwave generator 18 are arranged in the combination cooking appliance 10 , and they are each connected to and driven by the control unit 20 .

[0072] Cooked product 22 placed on a cooked product carrier 24 is placed in the cooking chamber 12. Cooked product carrier 24 may be a tray, plate, or rack inserted into a slot 26 inside the cooking chamber 12.

[0073] The heating device 14 and the steam generator 16 are arranged to provide a specific cooking chamber climate in the cooking chamber 12. The cooking chamber climate is specified by the control unit 20, in particular depending on the cooking program being run. The microwave generator 18 is designed to generate electromagnetic radiation in the form of microwaves with a wavelength λ and feed it into the cooking chamber 12. Preferably, microwaves with a frequency of 2.45 GHz (corresponding to a wavelength λ of 12.45 cm in a vacuum) are fed into the cooking chamber 12. The microwave radiation introduced into the cooking chamber 12 can apply (additional) energy to the cooking product 22, which is thereby cooked.

[0074] In addition, a core temperature detector 28 is provided in the cooking chamber 12, which is designed to monitor the core temperature of the cooking product 22 during the cooking process, assuming that the core temperature detector 28 is inserted into the cooking product 22. In the case of a piece of meat such as roast meat, the core temperature detector 28 can be used to determine when the roast meat has reached a desired degree of doneness by measuring the core temperature.

[0075] The core temperature detector 28 has a handle portion 30 and a measuring portion 32 adjacent to the handle portion 30. The handle portion 30 is designed so that a user can hold the core temperature detector 28 there.

[0076] On the other hand, the measuring portion 32 implements the actual function of the core temperature detector 28, namely the determination of the core temperature inside the cooking product 22. To implement the core temperature sensing, the core temperature detector 28 is at least partially inserted into the cooking product 22. Figure 1 As shown, the core temperature detector 28 can be inserted into the culinary product 22 over the entire length of the measuring portion 32 or, in particular in the case of small or less voluminous culinary products 22 , only partially.

[0077] Furthermore, the core temperature detector 28 has a microwave catcher 34 which is arranged at the transition between the measuring portion 32 and the handle portion 30. Thus, when inserted, the microwave catcher 34 is located outside the cooking product 22 or at most rests against the cooking product 22 with its front side.

[0078] The microwave catcher 34 is designed to protect the core temperature detector 28 from microwave energy when the microwave operation of the combination cooking appliance 10 is turned on (ie, when microwaves are fed into the cooking chamber 12 ).

[0079] In order to achieve a trapping effect, the microwave trap 34 is designed as a quarter-wave trap, which is tuned to the wavelength of the electromagnetic radiation used in the cooking chamber 12. To this end, the microwave trap 34 has a geometric length (trap depth) corresponding to approximately one-quarter of the electrical length of the wavelength of the electromagnetic radiation used in the cooking appliance 10.

[0080] The core temperature detector 28 is connected to the control unit 20 in a signal transmission manner via a cable 36. In this way, the core temperature detector 28 can forward the measured core temperature to the control unit 20 so that the control unit 20 can monitor the cooking process and, if necessary, adjust the cooking process taking into account the measured core temperature.

[0081] Refer to the following Figure 2 Additional features of the core temperature detector 28 are described in more detail.

[0082] exist Figure 2 , the core temperature detector 28 is divided into two parts, which are separated from each other by a dotted line in the drawing. Figure 2The area above the middle dashed line is the measuring portion 32, which is at least partially inserted into the cooking product 22 to measure the temperature inside the cooking product 22. Below the dashed line is the handle portion 30, which is used to operate the core temperature detector 28. The microwave catcher 34 is arranged at the level of the dashed line, and therefore between the measuring portion 32 and the handle portion 30, i.e., at the transition.

[0083] For temperature detection, several temperature sensors 38 are arranged along the measuring portion 32, in this case three temperature sensors 38. Of course, any other number of temperature sensors can be envisaged. Preferably, the temperature sensors 38 are evenly arranged along the measuring portion 32. At least one additional temperature sensor 38 can also be arranged in the handle portion 30, which temperature sensor 38 can be used as a reference measurement of the cooking chamber temperature or as part of a microwave load sensor.

[0084] The temperature sensor 38 is surrounded by a measuring rod 40, which is configured as a hollow cylinder in the embodiment shown. In addition, a line 42 is provided in the measuring rod 40, which extends along the measuring part 32 and connects the temperature sensors 38 to each other. Starting from the temperature sensor 38, the line 42 extends into the handle part 30 and forms a signal transmission component of the cable 36. Therefore, the core temperature value detected by the temperature sensor 38 can be forwarded to the control unit 20.

[0085] In order to allow the metal measuring rod 40 to be inserted into the culinary product 22 , the measuring rod 40 is provided at its free end facing away from the handle part 30 with a tip 44 which adjoins an end part 46 which widens conically in the direction of the handle part 30 and opens into a straight shaft part 48 .

[0086] Close inspection reveals that the shaft portion 48 houses the wire 42 and the temperature sensor 38 .

[0087] Furthermore, a contact tube 50 is provided, which can be formed integrally with the measuring rod 40 or can be present separately from the measuring rod 40 and attached to the measuring rod 40. For example, the measuring rod 40 can be welded, in particular laser welded, to the contact tube 50.

[0088] As in Figure 2 3 that the contact tube 50 has a larger diameter than the measuring rod 40, so that a transition section 51 is provided, wherein the measuring rod 40 widens conically in the direction of the handle section 30 until the diameter corresponds to the diameter of the contact tube 50. The transition section 51 can be designed integrally with the measuring rod 40 and / or the contact tube 50 or can be separate from the measuring rod 40 and the contact tube 50 and welded, in particular laser welded, to both the measuring rod 40 and the contact tube 50.

[0089] The contact tube 50 extends at least partially into the handle part 30 and has a handle-side end 52 facing the handle part 30 .

[0090] like Figure 2 As shown, the handle-side end 52 terminates approximately halfway through the handle portion 30 .

[0091] Furthermore, a cable 36 is guided in the contact tube 50 , which cable 36 extends into the handle-side end 52 and in the direction of the measuring section 32 .

[0092] The handle portion 30 will now be described in more detail.

[0093] In the handle portion 30 of the core temperature detector 28, a handle 54 is provided, which is made of, for example, plastic, preferably heat-resistant plastic, particularly PEEK. The handle 54 has an elongated cylindrical shape in the direction of the measuring portion 32, and has one end facing the measuring portion 32 and a second end facing away from the measuring portion 32.

[0094] The handle 54 is provided with a catcher-side opening 56 at its end facing the measuring section 32, which at least partially surrounds the microwave catcher 34. Preferably, the handle 54 is injection-molded around the microwave catcher 34 so that the microwave catcher 34 is firmly connected to the handle 54 in the region of the catcher-side opening 56.

[0095] In addition, the handle 54 has a knob 58 in the area around the trap-side opening 56, which is formed as a continuous radial protrusion completely surrounding the microwave trap 34. The knob 58 is used to safely operate the core temperature detector 28 without the user slipping off the handle 54.

[0096] The handle 54 has a cable side opening 60 at the end facing away from the measuring part 32 (which is opposite to the trap side opening 52). A cable duct 62 receiving the cable 36 extends from the cable side opening 60 to the trap side opening 56. Therefore, the handle 54 can be designed as a hollow cylinder. The handle side end 52 of the contact tube 50 is located at the half height of the cable duct 62, which roughly corresponds to the half height of the handle 54.

[0097] If already in Figure 1 As shown in FIG. 1 , a microwave trap 34 is disposed at a transition between the handle portion 30 and the adjacent measuring portion 32 , which will be discussed in more detail below.

[0098] Figure 2The microwave catcher 34 is shown to comprise a cylindrical catcher portion 64 designed in a pot-shaped manner, so that the catcher portion 64 has a bottom 68 at a first end 66 facing the handle portion 30 and a catcher opening 72 at a second end 70 facing the measuring portion 32. The two ends 66, 70 are opposite each other. Thus, the bottom 68 is associated with the handle portion 30 and the catcher opening 72 is associated with the measuring portion 32. The catcher opening 72 is surrounded by an edge region 74.

[0099] In addition, the catcher portion 64 surrounds the contact tube 40, and the contact tube 40 extends from the measuring portion 32 to the handle portion 30 through the channel 76 in the bottom 68 of the catcher portion 64. Then, the catcher portion 64 contacts the contact tube 40 at the channel 76. In particular, the catcher portion 64 is laser welded to the contact tube 40 at the channel 76. In other words, the bottom 68 is configured to be closed up to the contact tube 40.

[0100] Furthermore, the microwave catcher 34 has a dielectric filling element 78 arranged in the catcher portion 64. More specifically, the dielectric filling element 78 is arranged between the contact tube 40 and the catcher portion 64.

[0101] The filling element 78 contacts the bottom 68 of the catcher portion 64 , for example, via an end surface, and contacts the inner side of the catcher portion 64 along its outer circumference.

[0102] For example, the dielectric filling element 78 may be a ceramic having a dielectric constant of 9 to 10 (at 20° C. and 1 GHz), in particular an alumina ceramic having a purity of at least 95%.

[0103] To allow the contact tube 40 to pass from the measuring portion 32 into the handle portion 30 , the dielectric filling element 78 is shaped as a hollow cylinder having a through opening 80 aligned with the channel 76 in the bottom 68 , so that the contact tube 40 extends at least partially through the channel 76 and the through opening 80 .

[0104] As in Figure 2 As can be clearly seen in the diagram, the contact tube 40 in the embodiment shown extends completely through the through opening 80 through the filling element 78. In this respect, the contact tube 40 also extends completely through the catcher portion 64. This results in the filling element 78, the contact tube 40 and the catcher portion 64 being arranged coaxially relative to one another.

[0105] Furthermore, an annular end element 81 is provided in the region around the catch opening 72 of the catch part 64, which rests on the end face 83 of the filling element 78 and completely surrounds the circumference of the contact tube 40, the annular end element 81 being fastened, in particular laser welded, to the contact tube 40. The annular end element 81 serves to hold the dielectric filling element 78 in the microwave catch 34 in a captive manner.

[0106] The annular end element 81 is preferably made of an electrically conductive material. The annular end element 81 is particularly preferably made of a metal or an alloy.

[0107] The microwave trap 34 is designed to prevent the handle 54 from overheating, and thus prevent the entire core temperature detector 28 from overheating. To achieve this, the contact tube 50 is in contact with the cable 36 in some way, which will be referred to below. Figure 3 This is explained with reference to FIG6 .

[0108] First, based on Figure 4 The structure of the cable is described in more detail.

[0109] The cable 36 includes at least the wires 42 enclosed by a shield 82. The shield 82 is in turn surrounded by a wire jacket 84.

[0110] The shield 82 is used to protect the interior of the cable 36 (ie, the at least one wire 42 ) from electromagnetic interference.

[0111] like Figure 3 As shown, the shield 82 can be a braided shield. For example, the braided shield is designed as a copper wire braided around at least one wire 42. The wiring is bare or tinned. In any case, the shield 82 is made of a conductive material.

[0112] At least one wire 42 is preferably made of copper wire 86 and is insulated with an additional sheath 87. In this way, the wire 42 can be insulated from the shield 82 and the optional additional wires 42. Figure 4 As shown, the cable 36 preferably includes six wires 42 .

[0113] Alternatively, the shield 82 may also be a foil. The outer wire sheath 84 is used to protect the interior of the cable from moisture and other liquids coming from the cooking chamber 12. The outer wire sheath 84 may be made of PTFE.

[0114] The outer wire sheath 84 may be made of polytetrafluoroethylene (PTFE) and have a wall thickness greater than 0.3 mm, for example in the range of 0.35 mm to 1 mm, preferably from 0.45 mm to 0.7 mm. This represents a significant enhancement of the outer PTFE wire sheath 84 compared to conventional sheaths, which typically have a wall thickness less than 0.1 mm, particularly in the range of 0.01 mm to 0.05 mm. This allows the temperature inside the cable 36 to remain low during microwave operation of the combination cooking appliance 10, so that the individual wires 42 do not overheat. The wires 42 are better shielded due to the outer wire sheath 84 having an appropriate wall thickness.

[0115] Finally, the outer wire sheath 84 with its wall thickness ensures that the distance between the shield 82 (directly) surrounded by the outer wire sheath 84 and the metal of the cooking chamber 12 (e.g. the cooking chamber wall) is sufficiently large. The outer wire sheath 84 therefore provides (electromagnetic) shielding for the wire 42, in particular in addition to the shield 82, due to its wall thickness. Due to the wall thickness of the outer wire sheath 84, it is ensured in particular that the wire 42 is optimally positioned in the electric field present in the cooking chamber 12.

[0116] By attaching the cable 36 to the contact tube 50, the cable 36 is fixed in a captive manner in the handle portion 30. For this purpose, the cable 36 in the handle portion 30 has a sheath-free region 88. In this sheath-free region 88, the contact tube 50 forms a contact point 90 with the cable 36.

[0117] The sheath-free region 88 is characterized in that the portion of the cable 36 is stripped (i.e., released from the outer cable sheath 84) so ​​that the portion below the cable 36 (i.e., the shield 82) is exposed to the outside. This allows the contact tube 50 to contact the shield 82 via the contact point 90. The sheath-free region 88 is provided in the handle portion 30 and extends into the microwave trap 34 in the direction of the measuring portion 32.

[0118] In principle, the portion of the shield 82 that is not surrounded by the outer sheath 84 defines the spatial extent of the sheath-free region 88. The sheath-free region 88 extends into the microwave trap 34.

[0119] Adjacent to the sheath-free region 88, an insulating region 92 of the cable 36 is provided in the direction of the handle part 30, in which the shield 82 is not released from the wire sheath 84 and in which the handle-side end 52 of the contact tube 50 is arranged. The handle-side end 52 thus rests on the outer wire sheath 84. The handle-side end 52 of the contact tube 50 is in particular crimped onto the outer wire sheath 84, whereby a secure connection between the cable 36 and the contact tube 50 is achieved. The insulating region 92 extends out of the handle 54 into the control unit 20.

[0120] Adjacent to the unshielded region 88 in the direction of the measuring section 32, an unshielded region 94 is provided, in which the cable 36 is released from the shielding 82, so that only the line 42 extends into the measuring rod 40. In this respect, the unshielded region 88 is arranged between the insulating region 92 and the unshielded section 94. Preferably, the shielding 82 ends before the measuring rod 40. Particularly preferably, the shielding 82 ends in the microwave trap 34.

[0121] The contact point 90 is described in more detail below.

[0122] More specifically, the contact tube 50 contacts the shield 82 of the cable 36 in a conductive manner at the contact point 90 so that current (for example, current generated due to the influence of microwave radiation on the measuring rod 40, the collector portion 64 and the contact tube 50) can flow between the shield 82 and the contact tube 50.

[0123] The contact point 90 can be formed by a radially inwardly oriented projection 96 of the contact tube 50, which projection 96 is produced in particular by rolling the contact tube 50 onto the cable 36. This is particularly evident in FIG. 6 .

[0124] Rolling is a process in which the contact tube 50 is first pushed onto the shield 82 and then at least partially deformed by a radially inwardly directed force, so that a projection 96 is formed on the circumference of the contact tube 50 in contact with the shield 82. In this respect, the contact tube 50 is crimped onto the shield 82 by means of the contact point 90, so that the contact tube 50 and the shield 82 are captively connected to each other.

[0125] Additionally, the contact tube 50 may be in substantially complete contact with the shield 82 at the contact point 90 along the circumference of the shield 82 such that the contact point 90 forms a continuous contact ring.

[0126] The contact ring may be formed by a continuously formed protrusion 96 completely around the circumference of the shield 82 .

[0127] like Figure 3 and Fig. 6A As shown, a counter-pressure element 98 can also be provided, which is designed to exert a radially outwardly directed force on the shield 82 so that the shield 82 is pressed outwardly against the contact tube 50. In this way, the shield 82, which is configured to be mechanically flexible in any case, can be stretched outwardly to achieve a better electrical contact between the shield 82 and the contact tube 50.

[0128] The counter-pressure element 98 may be a metal sleeve which is pushed onto the wire 42 in the jacket-free region 88 so that the shield 82 located above the wire 42 is pushed radially outward. Fig. 6A It is shown that the wire 42 is kinked outwards in the direction of the shield 82 due to the counterpressure element 98 .

[0129] Alternatively, if Figure 6B As shown, a pressure element 99 formed as a metal sleeve is provided. The pressure element 99 is pushed onto the wire 42 in the jacket-free area 88, so that the shield 82 is located within the pressure element 99 formed as a sleeve and is particularly circumferentially completely surrounded by the pressure element 99. The sleeve is connected to the shield 82 in an electrically conductive manner, particularly crimped to the shield 82.

[0130] Furthermore, the sleeve has a portion via which the sleeve is connected (mechanically and / or electrically) to, in particular rolled onto, the contact tube 50. This portion thus provides an outward counterpressure for rolling onto the contact tube 50, which is why the pressure element 99 acts as a counterpressure element for the contact tube 50. For this purpose, this portion can have a larger diameter than the rest of the sleeve.

[0131] In this respect, the sleeve serves to form an (indirect) contact point 90 which connects the shield 82 and the contact tube 50 to one another, in particular in an electrically conductive manner.

[0132] However, the counterpressure element 98 or the pressure element 99 can also be omitted. Figure 5 An embodiment without counterpressure element 98 or pressure element 99 is shown in FIG.

[0133] In any case, a direct or indirect contact point 90 is formed in the sheath-free region 88 , via which the contact tube 50 is directly or indirectly (at least) electrically connected to the cable 36 .

[0134] like Figure 3 and Figure 6B As shown, the contact tube 50 can not only be in contact with the shield 82 via the contact point 90, but the contact tube 50 can also be crimped into the insulating part 92 via at least one recess 100 on the wire sheath 84. As a result, the contact tube 50 is particularly firmly connected to the cable 36 and, moreover, moisture is prevented from penetrating via the cable-side opening 60 of the handle 54.

[0135] The recess 100 may also be designed as an inwardly directed protrusion 96 which presses at least with its apex against the wire sheath 84. A continuous recess around the circumference of the cable 36 is also conceivable and preferred.

[0136] In order to keep the heat input into the handle 54 as low as possible, a certain distance d1 is selected between the handle-side end 52 of the contact tube 50 and the contact point 90 .

[0137] The distance d1 from the contact point 90 to the handle-side end 52 corresponds to the electrical length of the microwave radiation in the handle portion 30, which is shorter than or equal to one quarter of the wavelength of the microwave radiation used in the combination cooking device 10. The distance d1 is measured from the center M1 of the contact point 90 to the center M2 of the handle-side end 52, wherein the two centers are located on the same rotation axis Rm.

[0138] The contact point 90 is particularly preferably arranged at a minimum distance d2 from the bottom 68. The distance d2 may be in the range of 0.1 mm to 4 mm. The distance d2 is measured from the center point M1 of the contact point 90 to the center point M3 of the bottom 68, the two center points being located on the same center rotation axis Rm.

[0139] In addition, the catcher opening 72 may have a distance d3 to the handle-side end 52, the distance d3 corresponding to the electrical length of the microwave radiation in the handle portion 30, which is shorter than or equal to one quarter of the wavelength of the microwave radiation used in the combination cooking appliance 10. The distance d3 is measured from the center M2 of the handle-side end 52 to the center M4 of the catcher opening 72, the two centers being located on the same rotation axis Rm.

[0140] like Figure 8 , Fig. 9 and Fig.10 The reduced heat transfer achieved through the location of the contact point 90 is shown to be based on findings obtained from simulations of the E-field.

[0141] exist Figure 7 The simulation model is shown in . In this model, the core temperature detector 28 can be seen, which is fully inserted with its measuring rod 40 into the simulated cooking product, which in this case is a water medium as a substitute for the cooking product. The microwave radiation is fed from the right side as a coaxial mode between the cable 36 and the outer boundary layer (PEC for simulation). At the bottom left is the port (at the bottom of the water) that absorbs the output waves. Based on this simulation, the power loss density in the handle 54 and the electric field strength or surface current can be calculated.

[0142] Figure 8 A cross section along a core temperature detector 28 not according to the invention is shown, wherein the handle-side end 52 has a distance d corresponding to the electrical length of the microwave radiation in the handle portion 30, which is greater than a quarter of the wavelength of the microwave radiation used in the combined cooking appliance 10. The E-field reflected at the water on the left is shown similarly to the cooking product 22. The E-field intensity is shown based on a scale in V / m (based on 1 W excitation), wherein the brighter areas 102 correspond to high E-fields and the darker areas 104 correspond to lower E-fields.

[0143] Figure 8The simulation in shows that the handle-side end 52 is located at the maximum of the E-field. This is disadvantageous and leads to higher currents along the contact tube 50 and the handle 54, so that the handle 54 experiences a particularly strong energy input from the E-field.

[0144] This is also Fig. 9 As shown in the figure, it shows that Fig. 9 As can be seen, the handle 54 (upper line in the figure) experiences a particularly strong energy input compared to the other components.

[0145] Fig.10 Shown with Figure 8 Same simulation, except that the handle side end has a distance d1 corresponding to the electrical length of the microwave radiation in the handle portion 30, which is less than one quarter of the wavelength of the microwave radiation used in the combination cooking appliance 10. Therefore, the handle side end 52 is located at the minimum of the E field.

[0146] Therefore, with Fig. 9 Compared with the arrangement of the handle 54 in FIG. 5 , the handle 54 experiences less energy input. Therefore, the handle 54 heats up less.

[0147] This is also Fig.11 , where the handle 54 has the lowest energy input compared to the other components and Fig. 9 It is also an order of magnitude lower.

Claims

1. A core temperature detector (28) of a combined cooking utensil (10) for cooking a cooking product (22), the core temperature detector (28) comprising a measuring portion (32) and a handle portion (30), in, A contact tube (50) is provided, which extends at least partially into the handle part (30) and has a handle-side end (52) facing the handle part (30), wherein a cable (36) extending from the handle part (30) into the measuring part (32) is guided in the contact tube (50), The cable (36) has a sheath-free area (88) in the handle part (30), in which the contact tube (50) together with the cable (36) forms a contact point (90), wherein the contact point (90) has a distance d1 to the handle-side end (52), the distance d1 corresponding to the electrical length of the microwave radiation in the handle part (30), the electrical length being shorter than or equal to one quarter of the wavelength of the microwave radiation used in the combination cooking appliance (10).

2. The core temperature detector (28) according to claim 1, characterized in that: The core temperature detector (28) has a microwave catcher (34), which includes a pot-shaped catcher part (64), the pot-shaped catcher part (64) having a catcher opening (72) aligned with the measuring part (32) and a bottom (68) provided with a central channel (76) in the direction of the handle part (30), wherein the contact tube (50) extends through the central channel (76), in particular, wherein the contact tube (50) contacts the bottom (68) at the central channel (76), and more preferably, wherein the contact tube (50) is laser welded to the bottom (68) at the central channel (76).

3. The core temperature detector (28) according to claim 1 or 2, characterized in that: The contact tube (50) contacts the shield (82) of the cable (36) at the contact point (90) in an electrically conductive manner, wherein the shield (82) is in particular a braided shield.

4. The core temperature detector (28) according to claim 3, characterized in that: The handle-side end (52) of the contact tube (50) is arranged in an insulating region (92) of the cable (36), in which the shield (82) is surrounded by an outer cable sheath (84).

5. The core temperature detector (28) according to any one of claims 3 or 4, characterized in that: a counterpressure element (98) is arranged in the jacket-free region (88) below the shield (82) and is designed to exert a radially outwardly directed force on the shield (82) so that the shield (82) is pressed outwardly against the contact tube (50), or A pressure element (99) is arranged in the jacket-free region (88) above the shield (82), the pressure element (99) forming the contact point (90) connecting the shield (82) to the contact tube (50).

6. The core temperature detector (28) according to any one of claims 3 to 5, characterized in that: The contact tube (50) contacts the shield (82) or the pressure element (99) substantially completely at the contact point (90) along the circumference of the shield (82) or the pressure element (99), so that the contact point (90) forms a continuous contact ring.

7. A core temperature detector (28) according to any one of the preceding claims, characterised in that The contact point (90) is formed by a radially inwardly oriented projection (96) of the contact tube (50), wherein the projection (96) is produced in particular by rolling the contact tube (50) onto the cable (36).

8. A core temperature detector (28) according to any one of the preceding claims, when dependent on claim 2, characterised in that The contact point (90) is arranged at a minimum distance d2 from the bottom (68).

9. A core temperature detector (28) according to any one of the preceding claims, when dependent on claim 2, characterised in that The catcher opening (72) has a distance d3 to the handle-side end (52), the distance d3 corresponding to the electrical length of the microwave radiation in the handle portion (30), which is shorter than or equal to one quarter of the wavelength of the microwave radiation used in the combination cooking appliance (10).

10. A combined cooking appliance (10) for cooking a cooking product (22), comprising a cooking chamber (12), a microwave generator (18) and a control unit (20), the control unit (20) communicating with a core temperature detector (28) according to any one of the preceding claims, the core temperature detector (28) being arranged in the cooking chamber (12).

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