BATTERY-OPERATED FOOD THERMOMETER AND MANUFACTURING METHOD

Description

[0001] The invention relates to a food thermometer with a battery. The invention also relates to a method for manufacturing a food thermometer.

[0002] A food thermometer is a temperature measuring device designed and suitable for measuring the temperature of food during its preparation. A food thermometer can therefore measure temperatures that may occur during food preparation. It cannot measure temperatures that deviate significantly from these. Furthermore, a food thermometer is designed to withstand the environmental conditions that may occur during food preparation. Food thermometers are known from prior art, for example, from WO 2012 / 119725 A1 and EP 3 855 142 A1.

[0003] Typically, temperatures below 200°C are reached during food preparation. However, temperatures of up to 350°C can also be reached, for example, when baking a pizza. Temperatures above 350°C are generally not exceeded. A food thermometer according to the present invention is therefore designed so that temperatures above 400°C, preferably above 300°C, and particularly preferably above 250°C, can no longer be measured. The food thermometer is generally designed for use in a conventional oven, i.e., at temperatures up to 250°C or 220°C.

[0004] A food thermometer according to the present invention is not designed to measure very low temperatures, such as temperatures significantly below the sub-zero temperatures found in standard household freezers or freezers. Therefore, a food thermometer according to the present invention is not designed to measure temperatures below -70°C. In general, a food thermometer according to the present invention is designed to be unable to measure temperatures below -50°C, because food is usually prepared using heat, and very low temperatures are only used for freezing food.

[0005] A food thermometer according to the present invention can withstand a steam atmosphere. Therefore, a food thermometer is generally encapsulated in a waterproof manner. A food thermometer according to the present invention is resistant to common food ingredients such as the acid in lemons or vinegar.

[0006] A food thermometer according to the present invention is designed and suitable for being inserted into food being cooked in order to measure the internal temperature. For this purpose, a food thermometer may have an elongated probe with a pointed or at least a very thin end, enabling the probe to be inserted even into relatively firm foods such as meat. The probe includes a sensor with which a temperature can be measured. A food thermometer may also have a handle that is not designed and suitable for being inserted into the food. The handle can be grasped by a user to remove the food thermometer from the food. The handle may also include a sensor with which a temperature can be measured. In this case, the ambient temperature outside the food can also be measured.

[0007] A food thermometer according to the present invention requires electrical current for its operation. The food thermometer therefore includes a battery, i.e., a storage device for electrical energy. This storage device provides the electrical current required for the operation of the food thermometer. The battery is, in principle, a rechargeable battery.

[0008] The following requirements and issues must be considered when using a food thermometer. A battery is a temperature-sensitive component and therefore, for safety reasons, must be well protected from excessive heat. With a food thermometer that is inserted into food, the area inside the food remains relatively cool the longest. In a heated cooking environment, the food acts as a thermal insulator. It is therefore advantageous to position the battery in this area. However, the portion of the probe that is inserted into the food must be as thin as possible to allow the thermometer to be inserted without requiring much force. Therefore, the battery must have a particularly slim design if it is to be positioned in the area that will be inserted into the food.

[0009] The present invention aims to provide a food thermometer that is particularly well suited to the aforementioned requirements.

[0010] To solve the problem, a food thermometer comprises the features of claim 1. The dependent claim relates to a method for manufacturing the food thermometer. The dependent claims relate to advantageous embodiments.

[0011] The problem is solved by a food thermometer comprising a housing with a pointed end. The pointed end is designed and suitable for measuring the temperature inside food being cooked. A battery is located inside the housing. The battery is positioned at the pointed end of the food thermometer. The distance between the outermost tip and the battery is therefore small, for example, no more than 2 cm, preferably no more than 1 cm. The battery is surrounded by thermal insulation located between the housing and the battery. The battery is at least partially covered by the thermal insulation.

[0012] A battery is a component manufactured separately from other parts of a food thermometer. A battery generally consists of a casing, which can be made of metal. Inside the casing, there may be materials that allow electrical energy to be stored electrochemically. There are two electrical conductors. These conductors may pass through an inner wall within the battery casing. The battery can be a standard, commercially available battery, meaning it is sold independently of a food thermometer. The battery is typically elongated to fit neatly at the tip.

[0013] The thermal insulation encases the battery and therefore runs around it. The thermal insulation can thus be shaped like a tube. Preferably, the battery is completely enclosed within the thermal insulation, so that even the end faces of the battery are covered by the insulation.

[0014] However, it is also possible that the thermal insulation only partially covers the battery. For example, the thermal insulation may be grid-like and therefore only partially cover the battery. The thermal insulation could consist of several elements, which, for example, have been glued onto the battery. If there is a gap between the elements, the thermal insulation only partially covers the battery. The elements can be of different types. There may be one or more primary elements that contain a thermally insulating gas or a thermally insulating vacuum, thus providing thermal insulation. There may be one or more secondary elements that contain a phase-change material, thus providing thermal insulation. Even if a battery is only partially covered, it is still generally covered to a very large extent.In principle, at least 80% of the battery's surface is covered by thermal insulation, preferably at least 90%. Thermal insulation that completely covers the battery's surface, i.e., 100%, is preferred.

[0015] Thermal insulation, as defined in the invention, is a material that provides better protection against heat than the material adjacent to the thermal insulation. For example, the thermal conductivity of the thermal insulation can be lower than that of the adjacent materials. One or more adjacent materials can be made of metal, specifically stainless steel. For instance, the housing of the food thermometer and / or the battery housing can be made of metal, such as stainless steel. The metal housing of the food thermometer and / or the metal housing of the battery can then be adjacent to the thermal insulation material on one side, and / or the metal housing of the battery on the other.

[0016] Excessive heat can destroy a battery. Thermal insulation is not necessary to protect against such high temperatures. Therefore, thermal insulation is not provided in food thermometers, at least not when the battery is located at the tip. First, placing the battery at the tip of a food thermometer protects against heat because the food itself acts as a thermal insulator when the tip is inserted. Second, the thermometer tip must be thin to allow insertion without creating excessively large holes. Therefore, additional thermal insulation is undesirable because it increases the diameter of the food thermometer at the tip.

[0017] Batteries are subject to aging. Therefore, it's crucial that the battery in a food thermometer can provide sufficient electrical energy for operation over several years. Even after several years, a sufficient minimum capacity must remain so that the thermometer can measure temperatures for an adequate duration during food preparation. Otherwise, the thermometer might become unusable after only a short time.

[0018] The present invention is based on the finding that battery aging can be significantly reduced if the battery of a food thermometer is not only located at the tip of the thermometer but is also protected by a heat-insulating layer. This allows the use of a relatively low-capacity battery that is comparatively slim and compact. Thus, despite the heat insulation, the area at the tip of the food thermometer can be made thin. This also allows the use of smaller batteries, even if they are particularly sensitive to temperature aging.

[0019] A lithium-ion battery can be used, or preferably a battery with a solid electrolyte. For safety reasons, a battery with a ceramic electrolyte is also preferable. Alternatively, a supercapacitor can be used as the battery, for safety reasons as well.

[0020] Thermal insulation can be provided by a vacuum or by a highly insulating gas such as argon or krypton. In this case, there is generally no other component of the food thermometer between the tip and the battery. Alternatively, a temperature sensor may be located on the inner wall of the tip and powered by the battery. In this case, only the temperature sensor would be located between the tip and the battery.

[0021] Inside the thermometer, in the case of a vacuum or a heat-insulating gas, there is an inner wall that airtightly separates the space at the tip from the rest of the interior of the food thermometer. The battery is then located in this space at the tip. Heat insulation achieved through a gas or a vacuum is advantageously insensitive to heat. Furthermore, no destructive thermal stresses occur due to temperature changes.

[0022] The inner wall can be made of metal and, for example, bonded to the housing. Alternatively, the inner wall can be made of a plastic or resin. In this case, the plastic or resin is generally selected to withstand temperatures of at least 200°C or 220°C and therefore does not liquefy at these temperatures.

[0023] The thermal insulation can be formed by a phase-change material. This material can be housed together with the battery in a closed chamber located at the tip and / or within the tip itself. The phase-change material can be a liquid that evaporates upon the application of heat, thus changing its phase. It can also be in the form of a paste. The thermal insulation can consist of a combination of the phase-change material and a vacuum, or a combination of the phase-change material and a heat-insulating gas. This allows for further improvements in thermal insulation, minimizing the required installation space.

[0024] The heat storage capacity of the phase change material is preferably as large as possible in order to achieve a sufficiently large cooling effect for a long time.

[0025] The phase change temperature, at which the phase change occurs, is below the maximum possible operating temperature of the food thermometer, as otherwise no phase change can take place. The phase change temperature is generally selected to be below the maximum temperature to which the battery is exposed during discharge. Preferably, the phase change temperature is selected to be lower than the maximum charging temperature of the battery to enable particularly fast charging. This advantageously avoids longer charging times. The phase change temperature should therefore not exceed 70°C, preferably not more than 60°C. Furthermore, the phase change temperature is selected to be above typical storage temperatures. Therefore, the phase change temperature is generally above typical room temperatures.The phase change temperature should be at least 30°C, preferably at least 40°C. For the reasons mentioned above, the phase change temperature should be between 40°C and 53°C.

[0026] Preferably, the phase-change material is spaced apart from the housing of the food thermometer. This leaves, for example, an air-filled gap between the phase-change material and the housing. The gap is present at least when the temperature of the phase-change material is below the temperature at which the phase change occurs. This further improves the battery's protection against excessive heat and also prevents adverse thermal stresses.

[0027] The gap can be filled with a heat-insulating gas. A vacuum can be maintained within the gap to further improve thermal insulation. The thermal insulation can be particularly effective through such a combination of phase-change material and vacuum, or through a combination of phase-change material and a heat-insulating gas such as argon or krypton. The required installation space can still be relatively compact.

[0028] Preferably, the phase change material is dimensionally stabilized. This ensures that a gap exists between the housing of the food thermometer and the phase change material at least when the temperature of the phase change material is below the temperature at which the phase change takes place.

[0029] The thermal insulation can be formed by a composite material that encloses the phase change material. The phase change material can be dimensionally stabilized. The phase change material can be encapsulated and thus dimensionally stabilized. The phase change material can be macroencapsulated or microencapsulated. The phase change material can, for example, be encased in a film. The film can be stretchable to accommodate volume changes of the phase change material. The film can be made of plastic.

[0030] The heat-insulating material may have been glued to the battery. The battery may have been inserted into a casing made of heat-insulating material. The casing may have been sealed with a lid. Subsequently, the battery and heat insulation may have been placed inside the housing of the food thermometer.

[0031] The battery capacity should be at least 100 µAh, preferably at least 500 µAh, to ensure sufficiently long operating times for the food thermometer during food preparation. The battery capacity should not exceed 3 mAh, preferably not more than 2 mAh, to allow for a small diameter at the tip of the food thermometer.

[0032] The housing of the food thermometer can be made entirely or at least predominantly of metal, preferably stainless steel. The housing can therefore be highly thermally conductive to enable rapid temperature measurements. This allows the housing to withstand thermal, chemical, and mechanical stresses.

[0033] A box may be provided in which the food thermometer can be stored in a thermally protected manner. This ensures a substantially constant storage temperature. The box may also be designed to serve as a charger for the food thermometer's battery.

[0034] To manufacture a food thermometer with a thermally insulated battery, thermally insulating material can be placed inside a housing section with a pointed end. The insulating material can be heated, for example, to a temperature of at least 40°C, 60°C, or 80°C. The battery can then be inserted into the heated insulating material. When the insulating material is subsequently cooled, a gap can form between the insulating material and the housing. The battery can be held in a desired position within the housing by electrical conductors connected to it. These conductors can pass through an inner wall to fix their position within the food thermometer. The inner wall thus helps to retain the battery.

[0035] The heat-insulating material can include a phase-change material. The heat-insulating material that needs to be heated for manufacturing can be a granulate containing a phase-change material.

[0036] The use of a phase-change material is particularly advantageous because it provides excellent protection for the battery, even against excessively low temperatures, such as those below 0°C. If the food thermometer is to measure temperatures below, for example, 10°C or 0°C, it is preferably heated to a temperature above its phase-change temperature before measurement until the phase-change material has at least predominantly, and preferably completely, changed its phase. If a low temperature is subsequently measured, the phase-change material provides excellent protection for the battery against the cold.

[0037] The invention is explained in more detail below using examples illustrated by figures.

[0038] They show: Figure 1: Food thermometer with battery in a double-walled housing; Figure 2: Food thermometer with battery and temperature sensor inside a tip; Figure 3: Food thermometer with battery and inner wall; Figure 4: Food thermometer with battery and phase-change material; Figure 5: Food thermometer with battery in a housing.

[0039] The Figure 1Figure 1 shows a food thermometer 1. The food thermometer 1 comprises a pen-shaped housing 2 and a cap 3. The pen-shaped housing 2 is a tube that is gas-tightly sealed at one end by a tip 4. The pen-shaped housing 2 can be made of metal, for example, stainless steel. The cap 3 can be screwed and / or glued to the pen-shaped housing 2. The cap 3 can be made of plastic to serve as a heat-resistant handle. A battery 5 is located near the tip 4. The battery 5 is located inside a double-walled housing 6. The space 7 between the two walls of the double-walled housing 6 can be filled with gas, for example, argon or krypton. Alternatively, a vacuum can exist in the space 7. A phase-change material can be located in the space 7. The temperature at which the phase changes can be between 40°C and 53°C.

[0040] The double-walled housing 6 can be attached to the inner wall of the tip 4 at a single point or in a ring shape, thus being held at one end. Two electrical conductors 8 can connect the battery 5 to an electronics unit 9. The electronics unit 2 is generally located outside the double-walled housing 6. The two electrical conductors 8 then pass through the double-walled housing 6. The other end of the double-walled housing 6 can be held in place by means of the electronics unit 9 and the electrical conductors 8. A first temperature sensor 10, electrically connected to the electronics unit 9, can be attached to the inner wall of the pin-shaped housing part 2 adjacent to the double-walled housing 6. This first temperature sensor 10 can be used to measure the temperature of food being cooked when the food thermometer 1 has been inserted into the food. A second temperature sensor 11 is located at the cap 3 and is also attached to the inner wall of the housing.The second temperature sensor 11 can be used to measure the temperature prevailing in a cooking chamber.

[0041] The heat storage capacity of temperature sensors 10 and 11 is as small as possible so that the temperature sensors 10 and 11 can react particularly quickly to temperature changes.

[0042] A circumferential gap 12 exists between the double-walled housing 6 and the pin-shaped housing part 2. This gap 12 prevents thermal stresses and helps to protect the battery 5 from overheating.

[0043] A coil 13 may be present, for example, at the cap 3, through which the battery 5 can be inductively charged. The coil 13 can be connected to the electronics 9 via electrical conductors 14. Alternatively, the electrical conductors 14 can be connected to electrical contacts that are accessible from the outside. Charging can then take place via these contacts.

[0044] The electronics 9 can include a microcontroller that evaluates the temperature sensors 10 and 11. The microcontroller can control the charging of the battery 5. The electronics 9 can also include a radio unit that allows the food thermometer to wirelessly exchange data with an external device. This external device, such as a food processor, can then receive the measured temperatures and control the cooking process based on those temperatures.

[0045] The diameter of the conductors 8 is preferably small compared to other electrical conductors within the food thermometer 1, for example, small compared to the electrical conductors 14. This prevents the battery 5 from being heated via the electrical conductors 8.

[0046] Between tip 4 and battery 5 there is only thermal insulation and consequently no other components. The distance between the outermost end of tip 4 and the battery can be less than 2 cm or 1 cm.

[0047] The one in Figure 2 The embodiment shown differs from the one in the Figure 1 In the embodiment shown, the first temperature sensor 10 is arranged on an inner wall of the tip 4. Between the tip 4 and the battery 5 there is then the first temperature sensor 10, but no other components.

[0048] In the Figure 3An embodiment with an inner wall 15 is shown. The inner wall 15 separates a chamber 16 at the tip 4 from the rest of the interior of the food thermometer 1 in a gas-tight manner. The chamber 16 contains the battery 5 or a battery 5 with phase-change material applied to its surface. The applied phase-change material may be dimensionally stabilized. The applied phase-change material may be bonded in place. Alternatively, a vacuum may prevail in the chamber 16. The chamber 16 may be filled with a heat-insulating gas. The chamber 16 may also be completely filled with a material that includes a phase-change material or that is formed by the phase-change material.

[0049] In the Figure 4An embodiment is shown in which a dimensionally stable phase-change material 17 is attached to the battery 5. This can be achieved by filling an area at the tip 4 with phase-change material 17 and heating it. Subsequently, the battery was immersed in the phase-change material 17. Upon cooling, the phase-change material 17 contracted and thus detached itself from the pin-shaped housing part 2. To facilitate this detachment, a film can be provided that separates the phase-change material 17 from the pin-shaped housing part 2 at the tip 4.

[0050] In the Figure 5An embodiment is shown with a housing 18 in which the battery 5 is located. The battery 5 is spaced from the walls of the housing 18. The housing 18 can be gas-tight, allowing a vacuum to exist within it. Alternatively, a heat-insulating gas or a phase-change material can be housed in the housing 18. The housing 18 preferably does not contact the pin-shaped housing part 2 to improve heat protection. This is particularly important when a phase-change material is located in the housing 18. The housing 18 can be two-part, consisting of a container and a lid.

Claims

1. Food thermometer (1) with a housing (2, 3) comprising a pointed end (4) for a measurement of a temperature inside a product to be cooked, with a battery (5) located inside the housing (2, 3) and arranged at the pointed end of the food thermometer (1), wherein the battery (5) is encased by a thermal insulation located between the housing and the battery (5), or that the battery is at least partially covered by a thermal insulation located between the housing and the battery (5), characterized in that the battery (5) is located in a space (16) inside the food thermometer (1) in which a vacuum prevails or which is filled with a thermally insulating gas, wherein the thermally insulating gas is argon or krypton, or that the thermal insulation comprises a phase change material (17).

2. Food thermometer (1) according to the preceding claim, characterized in that the phase change material (17) is spaced from the housing of the food thermometer (1).

3. Food thermometer (1) according to one of the two preceding claims, characterized in that the phase change material (17) is dimensionally stabilized.

4. Food thermometer (1) according to the preceding claim, characterized in that the thermal insulation comprises a composite material comprising the phase change material or that the phase change material is encapsulated.

5. Food thermometer (1) according to one of the preceding claims, characterized in that thermally insulating material (17) is bonded to the battery (5) or the battery (5) is in an enclosure (17) of thermal insulating material.

6. Food thermometer (1) according to one of the preceding claims, characterized in that the thermal insulation is formed of a plurality of elements or that the thermal insulation is lattice-shaped.

7. Food thermometer (1) according to one of the preceding claims, characterized in that the battery (5) is selected to have a capacity of at least 100µAh and / or of not more than 3mAh.

8. Food thermometer (1) according to one of the preceding claims, characterized in that the housing (2, 3) consists entirely or at least predominantly of metal, preferably stainless steel.

9. Method for manufacturing a food thermometer (1) according to one of the preceding claims, characterized in that thermally insulating material is brought into a housing part of the housing of the food thermometer (1) and heated, the battery (5) is pushed into the heated thermally insulating material, and the thermally insulating material is cooled, wherein the thermally insulating material is a phase change material.

10. Method according to the preceding claim, characterized in that the battery (5) is held in such a way that the cooling causes the phase change material to contract and, thus, a gap (12) is created between the thermally insulating material and the housing.

11. Method according to the preceding claim, characterized in that the battery (5) is held by electrical conductors (8).

12. Method according to the preceding claim, characterized in that the electrical conductors (8) are passed through an inner wall (15).

13. Method according to the preceding claim, characterized in that the inner wall (15) contributes to holding the battery (5).