Core temperature probe for a cooking appliance

Abstract

A core temperature probe (10) of a cooking appliance (12) has an elongated tube (18) and an elongated circuit board (20) located inside the tube, on which several temperature sensors (40) are mounted. The circuit board (20) is curved, at least in sections, towards its side wall, and not flat, in order to increase its mechanical stability.

Description

[0001] The invention relates to a core temperature probe for a cooking appliance. Such core temperature probes are inserted into the food being cooked and indicate the instantaneous temperature inside the food. Typically, core temperature probes are designed to detect not only the temperature at the tip, i.e., at the end of the probe, but also temperatures in other areas of the probe.

[0002] There are different types of core temperature probes, namely wired and wireless, i.e., radio-based core temperature probes. The invention preferably relates to such wireless core temperature probes, i.e., those that transmit data via radio transmission. For this purpose, a control unit is provided in the cooking appliance itself, which communicates preferably bidirectionally with a radio module in the core temperature probe.

[0003] So-called SAW (Surface Acoustic Wave) sensors are also used as temperature sensors, which operate using acoustic or elastic surface waves. The temperature measurements achieved by these sensors are based on the fundamental principle that surface waves propagate at different speeds at different temperatures, or that the path length changes due to thermal expansion, or more generally, that they have different wave characteristics.

[0004] The corresponding sensors are mounted on a printed circuit board (PCB), which is elongated and located inside the tube. Such PCBs are rigid, flat, and thin bodies that can easily break under bending stress, especially pressure on their sides.

[0005] However, core temperature probes can also bend, or even deform, due to improper handling, for example, if the food is not sufficiently thawed and the probe is inserted with too much force. Users then simply bend these probes back into shape. This excessive bending can cause the circuit boards inside the probe to break or at least develop cracks.

[0006] The object of the invention is therefore to create a core temperature sensor which has an internal circuit board that is more stable against lateral bending.

[0007] This problem is solved by a core temperature sensor of a cooking appliance, comprising a hollow, elongated tube with a longitudinal axis, a plate-shaped circuit board located inside the tube and extending in its longitudinal direction along the longitudinal axis of the tube, in particular an antenna circuit board which has a strip-shaped form, and at least one temperature sensor located on the circuit board, in particular a surface acoustic wave sensor, wherein the circuit board, viewed in the direction of its longitudinally extending side wall, is curved at least section by section in the tube.

[0008] The present invention utilizes the effect that bending caused by a compressive force applied to the side wall of the strip-shaped or plate-shaped circuit board results in lower mechanical stresses in the circuit board if it is already curved perpendicular to the direction of force application.

[0009] As previously mentioned, the core temperature sensor according to the present invention is in particular provided with one or more SAW sensors, and the circuit board is designed as an antenna board, i.e. a radio module with corresponding antenna structures is formed on the circuit board.

[0010] Preferably, the side wall is curved in a wave-like pattern and housed within the tube. The wave shape is also evident in a view of the side wall of the strip-shaped or plate-shaped circuit board, with the side wall essentially running along the longitudinal axis of the tube. "Essentially" means that, of course, due to the curvature, the circuit board no longer has a linear shape in this view.

[0011] The curvature is not achieved by a raised surface on the outside of the circuit board, but rather by the fact that the opposite sides with the largest area (hereinafter referred to as the top and bottom surfaces) are essentially parallel to each other, with one side having a convex curvature and the other side having a concave curvature at the corresponding point, the curvature extending over the entire height of the circuit board, so that the circuit board has a cylindrical shape in the area of ​​the curvature, since the generating line of the top and bottom surfaces is a straight line.

[0012] Preferably, the curvature is present in the area of ​​the middle third, with respect to the longitudinal direction, but it can of course also extend over the entire length of the circuit board, so that no linear sections would be present when looking towards the side wall.

[0013] The SAW sensor(s) each have a housing that is in electrical contact with conductors on the circuit board via electrical contact conductors and can communicate with each other and / or with the antenna structure.

[0014] To ensure the flexibility of the circuit board in the area of ​​the sensors, these are preferably only attached to the circuit board in sections on their underside facing the board.

[0015] The fastening points between the circuit board and the SAW housing are limited, for example, to the electrical contact areas. A full-surface connection between the underside of the housing and the top side of the circuit board is therefore excluded, so that no sandwich or composite construction can be created over large areas, which would lead to a stiffening of the overall structure.

[0016] Preferably, several sensors are arranged longitudinally in a row one behind the other on the elongated, strip-shaped circuit board.

[0017] The circuit board can be installed in the tube in an elastically bent state, meaning it has a flat, plate-like initial state. However, in its installed state, i.e., inside the tube, the circuit board is then elastically bent to achieve the curvature or wave shape.

[0018] To achieve the curvature in the simplest way possible, a lateral spacer can be placed between the circuit board and the tube, which causes the circuit board to bulge at the desired point.

[0019] The spacer can be pre-mounted on the circuit board and thus inserted into the inside of the tube along with it.

[0020] Examples of such spacers are adhesive dots that are applied to the front and / or back of the circuit board and cure before the board is inserted into the tube.

[0021] As previously explained, an antenna structure is preferably applied to the circuit board.

[0022] The circuit board can be firmly mounted laterally in the tube at its front and / or rear end sections and may have a wave-like curvature in the area between the end sections.

[0023] To secure the circuit board, a fastening element, such as a wire or silicone, can be placed between the underside of the board and the tube. The wire can also be inserted later into the space between the tube and the circuit board. Other options, such as elastic leveling elements, are also possible.

[0024] The core temperature sensor according to the invention does not require an electrical energy storage device, which significantly improves its service life and maintenance.

[0025] Further features and advantages of the invention will become apparent from the following description and from the following drawings, to which reference is made.

[0026] The drawings show:

[0027] Fig. 1 a schematic longitudinal sectional view through a core temperature sensor according to the invention,

[0028] Fig. 2 a very schematic representation of the core temperature sensor according to Fig. 1 installed circuit board in installed state,

[0029] Fig. 3 a cross-sectional view through a core temperature sensor along line III-III in Fig. 1, and

[0030] Fig. 4 an enlarged schematic cross-sectional view through the core temperature sensor Fig. 1 inserted circuit board including adjacent sensor.

[0031] In Fig. 1 is a core temperature probe 10 a cooking appliance depicted with broken lines 12 to see. The core temperature probe has a handle. 14 as well as one from the handle 14 protruding probe to be inserted into the food 16 with a pipe 18 The pipe 18 extends into the handle 14 inside and is, for example, glued or overmolded within it.

[0032] The pipe 18 has a circular cylindrical outer shell and defines a longitudinal axis X with the cylindrical shell, where the tube 18 It may also have a different shape, e.g. oval or polygonal.

[0033] Inside the pipe 18The electronics and sensors for temperature measurement are at least partially housed within. This requires a plate-shaped, or more precisely, in this case, strip-shaped circuit board, originally designed in a single plane. 20 provided, on which conductive tracks are applied.

[0034] In Fig. 2 is the strip-shaped circuit board 20 depicted.

[0035] In the area of ​​the handle 14 is the circuit board 20 anchored in the area of ​​its handle-side end. The reference mark 22 This indicates an anchor point. 22 is symbolic in Fig. 2 shown.

[0036] In Fig. 1. It can be seen that the circuit board 20 still clearly above the anchor point 22 out into a recess 24 protrudes into the handle and can project freely in this area.

[0037] The handle 14In this area, for example, it is designed in two parts, with a basic part. 26 and one into a rear opening in the base part 26 inserted end part 28 , which is the exception 24 possesses inside.

[0038] As in Fig. As can be seen in Figure 1, the strip-shaped circuit board extends 20 with its longitudinal direction A along the longitudinal axis X.

[0039] The circuit board 20 has two opposite front faces 30 , 32 , representing the short sides, two opposite side surfaces representing the long sides 34 as well as a top 36 as well as a subpage 38 , which are oriented in opposite directions and represent the largest areas of the circuit board. The terms "top" and "bottom" are used here purely symbolically to distinguish the sides, since the core temperature sensor does not have a defined top and bottom.

[0040] On the top 36 are several sensors 40 applied one after the other in longitudinal direction A, of which only two are in Fig. 2 are shown.

[0041] These sensors 40 These are temperature sensors that measure the temperature of the core temperature probe. 10 at their measuring point.

[0042] As sensors 40 In this case, so-called Surface Acoustic Wave (SAW) sensors are used, each in its own housing. 42 are housed (see Fig. 4) The sensors 40 are chip-like in shape and mounted on a shell-like housing base. 44 Sticks to the inside.

[0043] The sensor is electrically operated. 40 via one or more contact conductors 56 and a cable routing 57 through the lower part of the housing 44 with a contact surface 58on the underside of the lower part of the housing 44 connected. This contact surface 58 is equipped with a corresponding contact surface 60 on the top side of the circuit board 20 via a conductive layer 62 bonded. This layer could be, for example, a silver sintering paste.

[0044] As in Fig. As can be seen in section 4, the casing is... 42 only over this layer 62 with the circuit board 20 connected and therefore not fully bonded to the underside of the circuit board 20 appropriate.

[0045] The circuit board 20 is in the pipe 18 Installed in an elastically curved manner, facing the side surface. 34 , i.e. in the direction of arrow B according to Fig. 2, i.e., in the unbent, flat initial state, this viewing direction would be parallel to the top and bottom surfaces. 36 , 38 and additionally perpendicular to the longitudinal direction A.

[0046] The slight bend in the strip-shaped circuit board 20 a curve that is curved at least in sections over its entire height, here in a section-by-section undulating curve. The undulating section bears the reference symbol. 70 .

[0047] The curved area can, this is not to be understood as a limitation, refer to the longitudinal direction A in the middle third of the circuit board. 20 lay.

[0048] So that the circuit board 20 in the pipe 18 in addition to the attachment point 22 where held, one or more fasteners can be attached at various points or locations in longitudinal direction A. 72 are planned to be in Fig.3 are represented symbolically. Here, for example, a thin wire extending in longitudinal direction A is shown, but a spherical part can also be used. Furthermore, it is possible to pre-print this part on the back of the circuit board. 20 to attach. The use of silicone gel in this area, possibly as a potting compound, is also conceivable.

[0049] To achieve the waveform or curvature, the circuit board 20 preferably on their sensors 42 opposite underside 38 a laterally protruding spacer 76 , which is preferably already pre-assembled before the circuit board 20 into the outer pipe 18 is being introduced.

[0050] This spacer 76 This could be, for example, a hardened adhesive spot that forms a bump on the underside. 38will be. To further stabilize the position of the circuit board, it can, for example, be positioned at its tip. 80 of the core temperature sensor 10 near end in the area of ​​the upper surface 36 also a spacer 82 possess, so that the circuit board 20 in a direction perpendicular to the top or bottom 36 or 38 is fixed in position.

[0051] The shape of the circuit board, which deviates from the original flat shape due to the curvature. 20 It reduces their bending stress when a force F is applied to the circuit board, which is introduced into the circuit board parallel to direction B. Such a force occurs, for example, when the tube 18 The material is bent or plastically deformed in direction B. The reduced bending stress lowers the breaking load for the circuit board material and also for the electronic components on the board. 20The limit is not exceeded; rather, the deformation remains within the elastic range.

[0052] Of course, there can be more than one wave-shaped curved area. 70 be planned.

[0053] The core temperature sensor 10 It has no internal energy storage and operates exclusively via radio, communicating with a control unit. 90 in the cooking appliance 12 communicated bidirectionally.

[0054] For this purpose, the circuit board 20 Antenna structures 92 trained. These antenna structures 92 can only be within the area of ​​the exclusion 24 be executed or also in the rest of the circuit board 20 , which also includes electrical connecting lines between the individual sensors 42 It may exhibit this, which depends on the circuit.

[0055] These connecting lines allow the number of antenna structures to be increased. 92can be reduced; if necessary, only one antenna structure can be used. 92 be sufficient, via which signals from all sensors would then be received 40 initiated and submitted.

Claims

[1] Core temperature sensor ( 10 ) of a cooking appliance ( 12 ), with a hollow, elongated tube ( 18 ) with a longitudinal axis (X), one inside the pipe ( 18 ) seated, plate-shaped, in their longitudinal direction (A) along the longitudinal axis (X) of the tube ( 18 ) running circuit board ( 20 ), in particular an antenna board which has a strip-shaped form, and with at least one temperature sensor ( 40 ), which is attached to the circuit board ( 20 ) is appropriate, where the circuit board ( 20 ) in direction (B) onto its longitudinally extending side wall (A) 34 ) appears to be curved, at least in sections. [2] Core temperature sensor according to claim 1, characterized by that the circuit board ( 20 ) runs in a wave-like curve, viewed with direction (B) towards the side wall ( 34 ) seen. [3] Core temperature sensor according to claim 1 or 2, characterized by that the curvature in the area of ​​the middle third of the circuit board, with respect to the longitudinal direction (A) ( 20 ) lies. [4] Core temperature sensor according to any one of the preceding claims, characterized by that the sensors ( 40 ) Housing ( 42 ) possess which have electrical contact conductors ( 56 ) with conductor tracks on the circuit board ( 20 ) are in electrical contact. [5] Core temperature sensor according to claim 4, characterized by that the housings ( 42 ) only partially on their circuit board ( 20 ) facing underside are attached to this. [6] Core temperature sensor according to claim 5, characterized by that mounting points between circuit board ( 20 ) and housings ( 42 ) are limited to electrical contact areas. [7] Core temperature sensor according to any one of the preceding claims, characterized bythat the sensors ( 42 ) in the longitudinal direction (A) of the circuit board ( 20 ) in a row one after the other on the circuit board ( 20 ) sit. [8] Core temperature sensor according to any one of the preceding claims, characterized by that the circuit board ( 20 ) in the pipe ( 18 ) is installed in an elastically bent position and the curvature is created by the elastic bending in the installed state. [9] Core temperature sensor according to any one of the preceding claims, characterized by that, in order to achieve the curvature, at least one laterally projecting spacer ( 76 ) between circuit board ( 20 ) and pipe ( 18 ) is available. [10] Core temperature sensor according to any of the preceding claims, characterized by that before mounting the circuit board ( 20 ) in the pipe ( 18 ) the spacer ( 76 ) on the circuit board ( 20 ) is attached, in particular a dried adhesive dot. [11] Core temperature sensor according to any one of the preceding claims, characterized by that the circuit board ( 20 ) at their front and / or rear end sections on the pipe ( 18 ) is supported and braced and has a wave-like curvature between the end sections. [12] Core temperature sensor according to any one of the preceding claims, characterized by that the circuit board ( 20 ) by at least one between the underside ( 38 ) the circuit board ( 20 ) and the pipe ( 18 ) positioned fastener ( 72 ) on the pipe ( 18 ) is held. [13] Core temperature sensor according to any one of the preceding claims, characterized by that the sensors ( 40 Surface acoustic wave sensors are. [14] Core temperature sensor according to any one of the preceding claims, characterized by that it is designed as a wireless core temperature sensor and can transmit data wirelessly. [15] Core temperature sensor according to claim 14, characterized by that on the circuit board ( 20 ) at least one antenna structure ( 92 ) is provided, which enables data exchange via radio.