OVEN WITH TEMPERATURE CONTROL UNIT

Description

TECHNICAL FIELD

[0001] The invention relates to a household oven with a temperature upper limit and lower limit control unit used for safety purposes.PRIOR ART

[0002] Temperature sensors are used to control the internal oven temperature of the ovens.

[0003] Generally, internal oven temperature control is provided by a temperature sensor secured on the cavity of the oven or inside the oven. The sensor transmits the required information to the control unit in accordance with the lower and upper limit temperatures with regard to a threshold value or provides the safe shut-down of the oven by means of a switch. Securing the sensor inside in such ovens may cause early malfunctions, and in ovens in which only one sensor is used, the function of determining the upper limit and lower limit values simultaneously may cause a malfunction after a while.

[0004] On the other hand, there are ovens using two separate sensors arranged outside the oven cavity. EP2775215B1 disclose an oven having a temperature sensor that senses a temperature of cooking space. A controller controls a heating capacity of heating elements in order to control cooking temperature to desired temperature. A climate sensor is arranged in opening of cooking space and temperature sensor is arranged outside the opening, such that heating capacity of heating elements is lowered with controller and the cooking space temperature falls below target temperature, when the temperature sensed by temperature sensor exceeds a threshold temperature. WO 2018 / 096369 A2 discloses an oven comprising a radiant temperature and convective heat transfer coefficient sensor having first and second sensor spades, with high and low emissivity coatings, connected to a heat sink through conductors.SUMMARY OF THE INVENTION

[0005] The object of the invention is to ensure that a single compact assembly measuring the heat on the cavity of a household oven performs all the measurements required for the cooking operation.

[0006] In order to achieve abovementioned objects, the invention relates to an oven comprising a cavity defining a cooking chamber, and a heat insulating layer provided for surrounding an outer wall of the cavity. The oven further comprises a hole which is provided on the heat insulating layer and a temperature measurement unit having a conductive probe extending inside the hole reaching the cavity from a distal end; a conductive bridge secured to temperature sensors from proximal end of the conductive probe in a heat transferrable manner and provided between a first temperature sensor and at least a second neighbouring temperature sensor. The first and second temperature sensors are positioned at close to each other on the conductive bridge element. Thus, by using a single conductive probe, it is possible to make temperature measurements for different purposes over the cavity at the same cooking times from the same point to be used for more than one purpose. In an alternative embodiment, it is possible to add third or fourth temperature sensors in connection with the conductive probe on the conductive bridge element. By setting the each temperature sensor to a predetermined threshold temperature value defined for a specific cooking operation, when the determined threshold value is reached, it operates by transmitting this for example to an electronic control unit, or an external or internal switch unit. For example, the first temperature sensor can be set to measure the maximum temperature upper limit of the oven, while the second temperature sensor can be set to measure a lower limit value relative to the set cooking temperature. Thus, with a single temperature measurement unit, both the upper limit can be provided against failures and the lower limit temperature measurements can be provided for the cooking operation at the same time.

[0007] In a preferred embodiment of the invention, the conductive probe is made of brass material. Thereby, the time for transmission of the temperature inside the oven to the temperature sensors through the conductive probe is faster. Alternatively, instead of brass, it may preferred to use steel or other alloys that will provide the same conductive properties and have a heat resistance similar to brass.

[0008] In a preferred embodiment of the invention, the length of the conductive probe is substantially equal to the thickness of a heat insulating layer in which the hole is located. Thus, it is ensured that heat insulating layer forms a barrier while the conductive probe transmits the heat and the transmission of the heat throughout is facilitated. In an alternative embodiment, the diameter of the hole can be chosen equal to or greater than the diameter of the conductive probe. If chosen equal, while the heat insulating layer provides heat by also surrounding the conductive probe; if chosen greater, the installation of the conductive probe on the outer periphery of the heat insulating layer becomes easier.

[0009] In a preferred embodiment of the invention, a connection element is provided at the proximal end of the conductive probe such that mounting to the cavity. Thereby, the conductive probe can be directly mounted in the cavity. Moreover, maintenance is facilitated by removing the conductive probe from the cavity when necessary. In an alternative embodiment, the connection of the conductive probe to the cavity can be a welding seam.

[0010] In a preferred embodiment of the invention, the conductive bridge element is in form of a metal strip, wherein at one side the conductive probe is mounted and at the opposing other side the first and second temperature sensors are mounted. Thereby, the loss during temperature transmission is minimized and the temperature sensors are provided to give more accurate results. Also, the conductive probe provides heat transfer from one point to the temperature sensors.

[0011] In a preferred embodiment of the invention, the first and second temperature sensors are arranged sequentially. Thereby, a compact structure is obtained and also the negative effect of the measurement performance due to the temperature sensors interacting with each other is prevented.

[0012] In a preferred embodiment of the invention the conductive bridge element is comprising a thoroughly formed hole and the distal end is having a narrowed section extending inside the hole (462). Thereby, it is ensured that the conductive probe is directly mounted to the bridge. The extension can be partially or completely placed into the opening.

[0013] In a preferred embodiment of the invention, the first and second temperature sensors comprise mechanical thermostats. Thus, without the need for an additional switch, both the temperature measurement is provided on the bridge and the power is turned off when the threshold values are reached. Alternatively, an electronic temperature sensor can be used instead of a mechanical thermostat. In such a case, which type of action will be applied when the threshold temperature value is reached is determined by a switch or a control unit attached to the temperature sensors.

[0014] In a preferred embodiment of the invention, the first temperature sensor has a temperature upper limit value set at 50 °C and above. Thus, if the temperature inside the oven exceeds the upper limit value, it is directly transmitted to the control unit and thereby the cooling fan of the oven is enabled. When it falls below the set limit value, it stops the operation of the cooling fan. For example, if the temperature inside the oven is set to 200 °C, the second temperature sensor will have a limit of 50°C in the range of 230-180°C. If the cooking chamber exceeds 230 °C and the operation of the cooling fan falls below 180 °C, it will ensured that the resistors are reactivated. Thereby, the temperature inside the oven is provided to fluctuate proximately to the set temperature.

[0015] In a preferred embodiment of the invention, the second temperature sensor has a temperature lower limit value set at 250 °C and below. Thereby, when the set temperature lower limit is reached, a safe shut-down of the oven is provided by means of the second temperature sensor.

[0016] In a preferred embodiment of the invention, an upper resistor and a lower resistor are provided in the cooking chamber. Thus, the resistors ensure that the cooking chamber is heated by electric current. Alternatively, magnetron and halogen heating elements can be used instead of resistors.

[0017] In a preferred embodiment of the invention, the conductive probe is arranged at a rear part of the cavity. Thereby, it prevents space occupation in the cooking chamber. Alternatively, the conductive probe can extend in the cooking chamber or be mounted on the top, bottom or sides of the cavity.

[0018] In a preferred embodiment of the invention, the conductive probe is in the form of a rod. Thus, a compact structure is formed and the advantage of space-saving is provided. Also, the rod structure ensures that the distance between the cavity and the conductive bridge element carrying the temperature sensors is maintained.BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 shows a schematic cross-sectional view of a household oven comprising a representative embodiment of the temperature measurement unit of the invention. Figure 2 shows a zoomed-in view of the temperature measurement unit of the oven given in figure 1. DETAILED DESCRIPTION OF THE INVENTION

[0020] In this detailed description, the development of the invention has been described without any limitation and only with reference to the examples for a better explanation of the subject.

[0021] In Figure 1, there is schematically shown an electrical oven with a temperature measurement unit (40) of the invention from one side. A metal box-like cavity (10) delimits a cooking chamber (2). An upper resistor (3) and a lower resistor (4) corresponding to the upper and lower parts of the cavity (10) are mounted on an inner wall (12). The upper and lower resistors (3,4) are activated by means of the control elements (not shown) located on a control panel (6). The control panel (6) carries a control unit (5). The control unit (5) is in the form of an electronic control card and includes a processor and a memory unit. A door (1) is hinged to the open outlet of the cavity (10) in such a way that it can be opened and closed. When the door (1) is closed, it covers the cooking chamber (2). An outer wall (14) of the cavity (10) is covered with a heat insulating layer (20) made entirely of glass wool. The heat insulating layer (20) is applied directly to the outer wall (14). A hole (24) is drilled on an outer periphery (22) of the heat insulating layer (20), reaching up to the cavity (10). The hole (24) is arranged in proximity to the upper corner of a rear part (16) in the outer wall (14) of the cavity (10). The hole (24) is in a cylindrical form drilled on the heat insulating layer (20). A conductive probe (48) made of brass material, which is in the form of a rod, is placed such that it extends along the cavity (10) and the hole (24) in order to provide heat transmission. An opening (18) is drilled by cutting in the rear part (16) of the cavity (10), and the conductive probe (48) extends vertically from the rear part (16) of the cavity (10) perpendicularly to the outer wall (14). The conductive probe (48) extends outward from the opening (18). A connection element (49) such as nut is fixed to a distal end (482) in such a way that it rests against the inner wall (12) of the cavity (10). When the connection element (49) rests against the cavity (10), the conductive probe (48) is fixed outwardly from the outer wall (14). A conductive bridge element (46) in the form of strip metal cut perpendicular to the conductive probe (48) is mounted at one proximal end (484) of the conductive probe (48) An hole (462) is formed by making a hole through the conductive bridge element (46). At the proximal end (484) of the conductive probe (48), a tapered extension (486) is formed that fits into the hole (462) of the conductive bridge element (46), fixing it to the conductive bridge element (46). The body length of the conductive probe (48) is equal to a width (H) of corresponding heat insulating layer. The width of the heat insulating layer (20) is constant along the rear part (16). A casing (30) covers the outer periphery (22) of the heat insulating layer (20) at a distance.

[0022] In Figure 2, there is provided a zoomed-in view of the temperature measurement unit (40). A first and a second temperature sensor (42, 44) in the form of a mechanical thermostat are mounted at a distance on the conductive bridge element (46). An L-shaped tab (461) extending over the conductive bridge element (46) keeps the first and second temperature sensors (42, 44) fixed on the conductive bridge element (46) from its corresponding part. The first temperature sensor (42) is placed on the conductive bridge element (46) in alignment with the conductive probe (48). Each temperature sensor (42, 44) has a terminal end (43, 45) facing outward. Terminal ends (43, 45) transmit an electrical signal to the control unit (5) by means of a cable (50).

[0023] The user adjusts the cooking temperature by means of a control button (not shown) on the control panel (6). The upper and lower resistors (3,4) are activated individually or in pairs, thereby heating the cooking chamber (2). When the cooking chamber (2) is heated, the conductive probe (48) transfers the heat to the conductive bridge element (46) through heat conduction. The first temperature sensor (42) is set with an upper limit of 50 °C. A cooling fan (not shown) is activated by the control unit (5) when the temperature of the cooking chamber (2) exceeds the set 50 °C limit due to any malfunction during cooking. On the other hand, when the temperature of the cooking chamber (2) is set to 180 °C, the cooling fan is activated when the temperature rises to 230 °C, when the temperature drops to 160 °C, the switch on the first temperature sensor (42) is triggered, thereby instructing the resistors (3,4) to be activated.

[0024] The second temperature sensor (44) is configured such that the set temperature of the cooking chamber (2) is activated according to its safe lower limit. When the temperature of the cooking chamber (2) reaches 250°C, the switch on the second temperature sensor (44) is triggered, thereby giving an instruction to cut the power sent via the control unit (5) or directly to the resistors (3,4). With this structure, both the lower temperature for safety purposes and the upper temperature limit maintaining the temperature of the cooking chamber (2) in the cooking operation at the same time can be controlled by temperature sensors (42, 44) arranged on the single conductive bridge element (46) and in case of exceeding the limit, action can be taken according to the determined scenario by comparing the predetermined values and the current temperature measured by the temperature sensors (42, 44) instantly at the same time.REFERENCE NUMBERS

[0025] 1Door40Temperature Measurement Unit2Cooking Chamber42First Temperature Sensor3Upper Resistor43Terminal End4Lower Resistor44Second Temperature Sensor5Control Unit45Terminal End6Control Panel46Conductive Bridge Element10Cavity461Tab12Inner Wall462Opening14Outer Wall48Conductive Probe16Rear Part482Distal End18Opening484Proximal End20Heat Insulating Layer486Extension22Outer Periphery49Connection Element24Hole50Cable30CasingHThickness of the Insulating Layer

Claims

1. An oven, comprising a cavity (10) defining a cooking chamber (2), a heat insulating layer (20) provided for surrounding an outer wall (14) of the cavity (10) and a hole (24) provided on the heat insulating layer (20) characterized in that a temperature measurement unit (40) is having a conductive probe (48) extending inside the hole (24) reaching the cavity (10) from a distal end (482); a conductive bridge (46) is secured to temperature sensors (42, 44) from proximal end (484) of the conductive probe (48) in a heat transferrable manner and provided between a first temperature sensor (42) and at least a second neighbouring temperature sensor (44) wherein the first and second temperature sensors are positioned at close to each other on the conductive bridge element such that temperature measurements for different purposes over the cavity are made by using a single conductive probe.

2. An oven according to claim 1, wherein the conductive probe (48) is made of a brass material.

3. An oven according to any one of the preceding claims, wherein the length of the conductive probe (48) is substantially equal to a thickness of the heat insulating layer (H) in which the hole (24) is located.

4. An oven according to any one of the preceding claims, wherein a connection element (49) is provided at the proximal end (482) of the conductive probe (48) mounting to the cavity (10).

5. An oven according to any one of the preceding claims, wherein the conductive bridge element (46) is in form of a metal strip, wherein at one side the conductive probe (48) is mounted and at the opposing other side the first and second temperature sensors (42, 44) are mounted.

6. An oven according to claim 5, wherein the first and second temperature sensors (42, 44) are arranged sequentially.

7. An oven according to claim 5-6, wherein the conductive bridge element (46) comprises a thoroughly formed hole (462) and the distal end (482) is having a narrowed section (486) extending inside the hole (462).

8. An oven according to any one of the preceding claims, wherein the first and second temperature sensors (42,44) comprise a mechanical thermostat.

9. An oven according to claim 8, wherein the first temperature sensor (42) has a temperature upper limit value set at 50 °C and above.

10. An oven according to claim 8-9, wherein the second temperature sensor (44) has a temperature lower limit value set at 250°C and below.

11. An oven according to any one of the preceding claims, wherein an upper resistor (3) and a lower resistor (4) are provided in the cooking chamber (2).

12. An oven according to any one of the preceding claims, wherein the conductive probe (48) is arranged at a rear part (16) of the cavity (10).

13. An oven according to any one of the preceding claims, wherein the conductive probe (48) has the structure of a rod.