JP2013174457A - Water level detection mechanism, steam generator and heating cooker - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water level detection mechanism capable of accurately detecting an accurate arrangement of a water tank and a water level of the water tank with a simple and safe configuration, a steam generator and a heating cooker.SOLUTION: A water level detection 5 includes a first electrode 51 attached to a case 1, a second electrode 52 attached to the case 1 in a state of being insulated from the first electrode 51, and a third electrode 53 insulated from the first electrode 51, and electrically connected to the second electrode 52 and attached to a water tank 2 so as not to be brought into contact with water in the water tank 2 when the water tank 2 is mounted on the case 1.

Description

  The present invention relates to a cooking device, a steam generator provided in the cooking device, and a water level detection mechanism that detects the water level of a water tank of the steam generator.

  In a heating cooker that accommodates an article to be heated in a heating chamber and performs cooking, the microwave oven function for cooking the article to be heated using radio waves (microwaves) or the article to be heated using infrared rays In addition to an oven function for cooking by heating, an apparatus having a steam heating function for cooking a heated article with high-temperature steam has been increasing.

  Thus, the cooking device provided with a steam heating function includes a steam generator for generating steam. The steam generator includes a heater that heats water, a water supply tank that is detachably disposed in the cooking device, and stores water, and a pump that supplies water from the water supply tank to the heater. ing. In the heating cooker, the water supply tank storing water is attached at a predetermined position. In the heating cooker, when heating of the article to be heated by the steam heating function is started, the steam generator sucks out the water in the water supply tank with a pump, and heats the sucked water with the heater. Generate steam.

  When the steam heating function is used, when water does not accumulate in the water supply tank or when the water in the water supply tank becomes small, steam is not generated or the generation amount becomes unstable, resulting in uneven heating of the article to be heated. May occur. Therefore, the heating cooker often has a function of detecting the amount of water stored in the water supply tank and notifying the user when the water runs out or decreases.

  As a method of detecting the amount of water remaining in the water supply tank, a method of detecting the water level of water remaining in the water supply tank and calculating the remaining amount of water from the water level is often used. Such detection of the water level is performed in a detection tank for indirectly measuring the water level. More specifically, the detection tank is provided with a plurality of electrodes having different lengths, and the water level is detected by observing the conductive electrodes.

  In such a water level detection mechanism that detects the water level by directly contacting the electrode with water (electric resistance type), the electrode is easily corroded, and the components of the electrode may be dissolved in the vapor, and the food is heated. It may not be appropriate for a cooker. In addition, since the electrode and water are in direct contact with each other and electricity flows, there is a possibility of electric leakage and there is a problem that safety is lowered.

  As a detection method for detecting the water level of the tank without causing such a problem, a method using a capacitance sensor attached to the side surface of the tank (capacitance type water level detection mechanism) has been proposed (for example, a special feature). (See JP 2011-136215). In such a capacitance sensor, a pair of insulated electrodes are attached to the outer surface of the tank to constitute a so-called capacitor. In such a capacitor, since water acts as a dielectric, the capacitance (charge) of the capacitor changes as the water level rises. That is, the capacitance sensor measures the change in capacitance and detects the water level of the tank.

JP 2011-136215 A

  However, when using the capacitance sensor installed as described above, it is difficult to distinguish when there is no water in the water supply tank and when the water supply tank is not arranged (is not arranged correctly). For this reason, some sensors are provided separately for detecting whether or not the water supply tank is correctly arranged, but the number of parts increases and the number of sensors increases, so that the control becomes complicated.

  Therefore, an object of the present invention is to provide a water level detection mechanism, a steam generator, and a heating cooker that can accurately detect the correct arrangement of the water tank and the water level of the water tank with a simple and safe configuration.

  In order to achieve the above object, the present invention provides a water level detection mechanism for detecting the level of water stored in a water tank that is detachably attached to a case, the first electrode, and the first electrode on the case. The second tank attached in an insulated state, and the water tank is in non-contact with the water in the water tank, and is electrically connected to the second electrode when the water tank is attached to the case. And detecting a capacitance of a capacitor including a third electrode attached to the first electrode, an electrode connecting the first electrode and the second electrode or the second electrode and the third electrode, and the first electrode. A water level detecting mechanism is provided.

  According to this configuration, when the water tank is not attached to the case, the first electrode and the second electrode constitute a capacitor, and when the water tank is attached to the case, A capacitor is comprised by the electrode which connected the 1st electrode and the 2nd electrode and the 3rd electrode. Thereby, it is possible to detect whether or not the water dunk is attached to the case by a change in capacitance, and it is not necessary to use a sensor for detecting the presence or absence of the water tank, and the configuration is simplified. Can be

  In addition, when water is contained in the water tank, the water acts as a dielectric, and the capacitor composed of the first electrode, and the electrode connecting the second electrode and the third electrode, diverts the water. It is divided into a body part and a part without a dielectric. Since the electrostatic capacity at that time is proportional to the fluctuation value of the water level, it is possible to detect the water level of the water tank more easily than the electrostatic capacity.

  Furthermore, since the first electrode, the second electrode, and the third electrode do not come into contact with the water stored in the water tank, the corrosion and rust of the electrode are prevented from mixing into the water in the water tank, It is possible to prevent a substance harmful to the human body or living body from being administered. Further, when used for edible purposes and the like, even if it is a harmless metal, it is possible to suppress changes in the appearance and taste (odor) due to the inflow of the metal component, and thus it is possible to prevent the quality of the article to be heated from deteriorating.

  The said structure WHEREIN: The connection electrode with which the said 2nd electrode and the said 3rd electrode were connected may be arrange | positioned in the position which a water surface touches when water is put into the said water tank.

  According to this configuration, the water level of the water tank can be detected without making the electrode larger than necessary. By reducing the size of the electrode, the metal material required for the electrode can be reduced. The third electrode may be attached to the lower part of the second electrode.

  The said structure WHEREIN: The said 2nd electrode is formed smaller than the said 3rd electrode. At this time, the ratio of the size of the second electrode and the third electrode is the capacitance when only the second electrode is used, and when the second electrode is connected to the third electrode. It may be determined so that the difference from the capacitance is larger than the resolution of the capacitance detection means.

  By forming the second electrode smaller than the third electrode, the capacitance of the capacitor formed by the first electrode and the second electrode when the water tank is not mounted, and the water tank It is possible to increase the difference between the capacitance of the capacitor formed by the first electrode when the is mounted and the electrode connecting the second electrode and the third electrode. The ratio of the size of the second electrode and the third electrode is not limited as long as the difference in capacitance is larger than the resolution of the capacitance detection means, but the larger the distance, the detection error, noise, etc. The presence or absence of the water tank can be reliably detected without being affected by disturbance.

  In the above configuration, the electrode connecting the second electrode and the third electrode has one end equal to or lower than the lower limit of the water level and the other end equal to or lower than the upper limit of the water level. It is arranged to exceed. With this configuration, it is possible to reliably detect the lower limit and the upper limit of the water level of the water tank.

  As a thing provided with the water level detection mechanism of the above-mentioned structure, there is a steam generator provided with a water supply pipe including a pump for sucking out water from the water tank, and a heater for heating water supplied from the water supply pipe. it can. Moreover, as what was equipped with such a steam generator, the heating cooker provided with the steam heating function which heats the articles | goods (foodstuff) inside a heating chamber with a steam can be mentioned.

  ADVANTAGE OF THE INVENTION According to this invention, the water level detection mechanism and heating cooker which can detect the correct arrangement | positioning of a water tank and the water level of a water tank correctly with a simple and safe structure can be provided.

It is a perspective view of an example of the cooking-by-heating machine concerning the present invention. It is the schematic of the steam generator provided with the water level detection mechanism concerning this invention. FIG. 3A is a diagram illustrating a state of the water level detection mechanism in a state where the water supply tank is attached to the case. It is a figure which shows the state of the water level detection mechanism of the state with which the water supply tank of the anhydrous state was mounted | worn with the case. It is a figure which shows the state of the water level detection mechanism of the state by which the water was stored in the water supply tank. It is a figure which shows the electrostatic capacitance detected with the capacity | capacitance detection circuit in each state of FIG. 3A-FIG. 3C. It is a block diagram which shows the connection state of the heating cooker concerning this invention. It is a flowchart which shows the operation | movement at the time of the steam heating cooking of the heating cooker concerning this invention. It is a figure which shows the other example of the 1st electrode of the water level detection mechanism concerning this invention, a 2nd electrode, and a 3rd electrode. It is a figure which shows the other example of the 1st electrode of the water level detection mechanism concerning this invention, a 2nd electrode, and a 3rd electrode. It is a figure which shows the other example of the 1st electrode of the water level detection mechanism concerning this invention, a 2nd electrode, and a 3rd electrode. It is a figure which shows the other example of the 1st electrode of the water level detection mechanism concerning this invention, a 2nd electrode, and a 3rd electrode.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of an example of a heating cooker according to the present invention. As shown in FIG. 1, the heating cooker A includes a heating chamber Hr, a door Dr, and a steam generator Vp. The heating cooker A is provided with a door Dr provided at a front opening, and stores an article to be heated (heating article) in the heating chamber Hr by opening the door Dr. In the heating cooker A, the article to be heated is placed on the turntable TT disposed inside the heating chamber, the door Dr is closed, and the article to be heated is cooked while rotating the turntable TT. Moreover, the opening 10 for mounting | wearing the water supply tank 2 which the steam generator Vp mentions later is provided in the front of the heating cooker A. The opening 10 is not limited to the front surface, and may be a side surface or an upper surface.

  The cooking device A has a microwave function for heating the article to be heated using radio waves (microwaves) from the radio wave generator, an oven function for heating the article to be heated using infrared rays from the heater, A steam heating function for heating the article to be heated using steam from the steam generator Vp is provided.

  The steam generator Vp is provided with a water level detection mechanism according to the present invention. Therefore, a steam generator equipped with a water level detection mechanism according to the present invention will be described with reference to the drawings. FIG. 2 is a schematic view of a steam generator equipped with a water level detection mechanism according to the present invention. In addition, in the steam generator Vp shown in FIG. 2, illustration of the heater which heats water and generate | occur | produces steam is abbreviate | omitted.

  In the heating cooker A, the steam generated by the steam generator Vp is directly in contact with the article to be heated which is a food, and it is preferable to supply water that is not contaminated with metal or the like. Therefore, the steam generator Vp is provided with a capacitive water level detection mechanism. As shown in FIG. 2, the steam generator Vp includes a case 1, a water supply tank 2, a water supply pipe 3, a pump 4, and a water level detection mechanism 5.

  The case 1 is a member that holds the water supply tank 2. The case 1 has a rectangular parallelepiped box shape in which one surface (here, the front surface of the heating cooker A) has an opening 10, and the water supply tank 2 is inserted and discharged from the opening 10. The case 1 is formed of a nonconductor such as resin.

  The water supply tank 2 is a rectangular parallelepiped container, and the upper surface is opened so that water can be put. The water supply tank 2 has a shape and a size that can be inserted from the opening 10 of the case 1.

  The water supply pipe 3 is a pipe for sending the water stored in the water supply pipe 2 to the heater, and is connected to the case 1. The water supply tank 2 is connected to the water supply tank 2 when inserted into the case 1. In addition, when the water supply tank 2 is not disposed in the case 1 (when the water supply tank 2 is pulled out), a valve 31 is attached to prevent the water in the water supply pipe 3 from flowing out. Yes. A pump 4 is attached to the water supply pipe 3. The pump 4 sucks the water stored in the water supply tank 2 into the water supply pipe 3 and sends it to the heater.

  Next, the water level detection mechanism 5 will be described. The water level detection mechanism 5 includes a first electrode 51, a second electrode 52, a third electrode 53, and a capacitance detection circuit 54. At least the second electrode 52 and the third electrode 53 are formed of the same conductor (same metal). Note that the first electrode 51 may also be formed of the same conductor (metal).

  As shown in FIG. 2, the 1st electrode 51 is a rectangular-shaped metal plate (conductor), and the outer surface is covered with nonconductors, such as resin. The 1st electrode 51 is arrange | positioned so that the outer surface of the water supply tank 2 inserted in case 1 may contact, and the longitudinal direction may cross | intersect the water surface of the water stored in the water supply tank 2 (FIG. 2). In the water level detection mechanism 5 shown in FIG. 1, the first electrode 51 is disposed so that the vertical direction is the longitudinal direction).

  The second electrode 52 is a rectangular electrode shorter than the first electrode 51. The second electrode 52 is attached to the case 1 so that the upper end thereof is the same height as the upper end of the first electrode 51 and is parallel to the first electrode 51. The first electrode 51 and the second electrode 52 are kept insulated, and the first electrode 51 and the second electrode 52 constitute a capacitor.

  The third electrode 53 is a rectangular electrode and is disposed on the outer surface of the water supply tank 2. The third electrode 53 is disposed so as to be in electrical contact with the second electrode 52 and not in contact with the first electrode 51 when the water supply tank 2 is attached to the case 1. When the water supply tank 2 is inserted (attached) to the case 1, the second electrode 52 and the third electrode 53 are in electrical contact. Thus, the second electrode 52 and the third electrode 53 are configured as an integral electrode.

  The second electrode 52 and the third electrode 53 need only be in electrical contact with each other, and the outer surface of the electrode 523 connecting the second electrode 52 and the third electrode 53 is covered with an insulator such as resin. Also good. And the capacitor is comprised with the electrode 523 (refer FIG. 3B mentioned later) which connected the 1st electrode 51, the 2nd electrode 52, and the 3rd electrode 53. FIG. The electrode 523 connecting the second electrode 52 and the third electrode 53 may have the same length as the first electrode 51 or may have a different length.

  The capacitance detection circuit 54 is a circuit that detects charges accumulated in a capacitor composed of the first electrode 51, the second electrode 52, and the third electrode 53, and detects capacitance based on the charges. The detected capacitance is converted into a voltage and output. More specifically, the capacitance is detected by applying an AC voltage or a pulsed DC voltage to the first electrode, the second electrode 52 and the third electrode 53 and measuring the stored charge. The capacitance detection circuit 54 is a well-known circuit and will not be described in detail.

  Such a capacitance detection circuit 54 is connected to the first electrode 51 and the second electrode 52, and includes the first electrode 51 and the second electrode 52 when the water supply tank 2 is not attached. The capacitance of the capacitor is detected. In addition, after the water supply tank 2 is attached to the case 1, the capacitance of the capacitor formed by the electrode 523 connecting the first electrode 51, the second electrode 52, and the third electrode 53 is detected. Furthermore, when the water supply tank 2 in which water is stored is attached to the case, the portion below the water surface of the electrode 523 connecting the first electrode 51, the second electrode 52, and the third electrode 53 is a dielectric material. The capacitor above the surface of the water is a capacitor that does not contain a dielectric. And it becomes equivalent to what these capacitors are connected in parallel.

  The principle of water level detection by the water level detection mechanism 5 having such a configuration will be described with reference to a new drawing. FIG. 3A is a diagram illustrating a state of the water level detection mechanism in a state where the water supply tank is not attached to the case, and FIG. 3B is a diagram illustrating a state of the water level detection mechanism in a state where the water supply tank in an anhydrous state is attached to the case. 3C is a diagram showing the state of the water level detection mechanism in a state where water is stored in the water supply tank, and FIG. 4 shows the capacitance detected by the capacitance detection circuit in each of the states of FIGS. 3A to 3C. FIG. 4 shows the detected capacitance, the output from the capacitance detection circuit 54 is a voltage, which is the same behavior as the capacitance.

  As shown in FIG. 3A, when the water supply tank 2 is not attached to the case 1, as described above, the first electrode 51 and the second electrode 52 constitute a capacitor (capacitor C1). . In the capacitor C1, since the area of the second electrode 52 is small and there is no water as a dielectric between the electrodes, the charge that can be stored, that is, the capacitance is small. At this time, the capacitance of the capacitor C1 is defined as a capacitance Q1 (see FIG. 4).

  As shown in FIG. 3B, the first electrode 51, the second electrode 52, and the third electrode 523 are configured by connecting the second electrode 52 and the third electrode 53 by attaching the water supply tank 2 to the case 1. A capacitor C2 is constituted by an electrode 523 connected to the electrode 53. At this time, the capacitance of the capacitor C2 is defined as a capacitance Q2 (see FIG. 4).

  Comparing the capacitor C1 shown in FIG. 3A and the capacitor C2 shown in FIG. 3B, the first electrode 51 is common and the opposing substrate is only the second electrode 52 in the capacitor C1, whereas in the capacitor C2, the first electrode 51 is This is an electrode 523 in which the two electrodes 52 and the third electrode 53 are connected. The capacitance of a capacitor is proportional to the area of the electrode when the distance between the two electrodes is the same and there is no dielectric between the electrodes. Therefore, the second electrode 52 that is one electrode of the capacitor C1 has a smaller area than the electrode 523 that connects the second electrode 52 and the third electrode 53 that are one electrode of the capacitor C2. Therefore, the capacitance Q1 of the capacitor C1 is smaller than the capacitance Q2 of the capacitor C2.

  The capacity detection circuit 54 detects the electrostatic capacity Q1 when the water tank 2 is not attached to the case 1, and detects the electrostatic capacity Q2 when the water tank without water is attached. The capacitances Q1 and Q2 are determined by the area of the second electrode 52 and the electrode 523 connecting the second electrode 52 and the third electrode 53. That is, by adjusting the area ratio between the second electrode 52 and the third electrode 53, the capacitance Q1 and the capacitance Q2 can be set to values that can be clearly distinguished. The area ratio between the second electrode 52 and the third electrode 53 is set so that, for example, the difference between the capacitance Q1 and the capacitance Q2 is larger than the resolution of the capacitance detection circuit 54. The capacitance Q1 and the capacitance Q2 can be set to values that can be clearly distinguished. Furthermore, the area ratio between the second electrode 52 and the third electrode 53 is such that the capacitance Q1 and the capacitance Q2 are as far apart as possible (for example, the capacitance that can be detected by the capacitance Q1). It is possible to more clearly distinguish between the electrostatic capacity Q1 and the electrostatic capacity Q2 by setting so as to be close to the minimum value.

  As shown in FIG. 3C, when water is stored in the water supply tank 2, the capacitor C <b> 3 is configured by the electrode 523 connecting the first electrode 51, the second electrode 52, and the third electrode 53. The capacitor C3 has a configuration of a capacitor C31 in which water is filled as a dielectric below the water surface. On the other hand, in the portion above the water surface, there is no water, that is, a capacitor C32 that is not filled with a dielectric (it can be interpreted that air is filled as a dielectric) is formed. Since water has a higher dielectric constant than air, the capacitor C32 has a larger capacitance than the capacitor C31.

  As shown in FIG. 3C, the capacitor C3 has a configuration in which a capacitor C31 without a dielectric and a capacitor C32 with water as a dielectric are connected in parallel. That is, the capacitance of the capacitor C3 is obtained by the sum of the capacitance of the capacitor C31 and the capacitance of the capacitor C32.

  As shown in FIG. 3C, in the capacitor C <b> 3, along the longitudinal direction of the electrode from the end of the opposing electrode (the electrode 523 connecting the first electrode 51, the second electrode 52, and the third electrode 53). The water surface fluctuates.

  That is, as the water level rises, the electrode area of the capacitor C31 decreases and the electrode area of the capacitor C32 increases. From this, when the water level rises, the capacitance of the capacitor C3 increases, and conversely, when the water level falls, the capacitance of the capacitor C3 decreases. In addition, since the electrode 523 which connected the 1st electrode 51 and the 2nd electrode 52, and the 3rd electrode 53 is a rectangle, and a longitudinal direction is a direction which cross | intersects a water surface, the change of the electrode area of the capacitor C31 and the capacitor C32 Becomes linear. From this, the change of the electrostatic capacitance of the capacitor C31 and the capacitor C32 also becomes linear, and the electrostatic capacitance of the capacitor C3, which is a combined capacity thereof, also changes linearly. That is, when the water level of the water supply tank 2 rises, the capacitance of the capacitor C3 also increases in proportion to the rise of the water level.

  For example, the capacitance of the capacitor C3 changes as shown in FIG. That is, in the capacitor C3, the capacitance is Q2 when the water level is lower than the lower limit, and when the water level rises, the capacitance increases in proportion to the water level up to the capacitance Qmax when the water level reaches the upper limit. To do. From the above, the water level of the water supply tank 2 can be detected by detecting the capacitance of the capacitor C3.

  In the water level detection mechanism 5 shown in FIGS. 2 and 3C, the upper end of the electrode 523 connecting the second electrode 52 and the third electrode 53 is equal to or higher than the upper limit of the water level stored in the water supply tank 2. Can also detect the upper limit of the water level. Further, if the lower end of the electrode 523 connecting the second electrode 52 and the third electrode 53 is arranged at the same level or lower than the lower limit of the water level stored in the water supply tank 2, the lower limit of the water level is detected. Is possible. Therefore, in the water level detection mechanism 5, the upper end of the second electrode 52 is disposed above the upper limit of the water surface (upper limit of the water level), and the lower end of the third electrode 53 is the same as the lower limit of the water surface (lower limit of the water level). The position is adjusted.

  The water level detection mechanism 5 uses such characteristics to detect whether or not the water supply tank 2 is attached and the water level when the water supply tank 2 is attached.

  The operation of the cooking device A provided with such a water level detection mechanism 5 will be described with reference to the drawings. FIG. 5 is a block diagram showing the connection state of the cooking device according to the present invention, and FIG. 6 is a flowchart showing the operation of the cooking device according to the present invention during steam heating cooking. Note that the block diagram shown in FIG. 5 shows only the portion that is driven when the article to be heated is heated by the steam heating function, and the illustration of the heating device that is driven by the microwave function and the oven function is omitted. ing.

  As shown in FIG. 5, the cooking device A has a configuration in which an input unit Sc, a display unit Mt, a heater Ht, a pump 4, a water level detection mechanism 5 (capacity detection circuit 54), and a memory Mem are connected to a control circuit Cont. have. The control circuit Cont includes an arithmetic processing unit such as a microcomputer, and receives an operation instruction signal from the input unit Sc and a signal indicating the presence / absence of a water supply tank and a water level from the water level detection mechanism 5. The control circuit Cont is a circuit that drives the pump 4 and the heater Ht, and displays the state of the heating cooker A on the display unit Mt.

  The memory Mem is a storage unit, and includes a table for the control unit Cont to calculate the water level stored in the water supply tank 2 based on the signal sent from the capacity detection circuit 54. . In addition, a storage area is provided for temporarily storing the obtained information and the results of calculations performed by the control circuit Cont.

  The capacitance detection circuit 54 detects the capacitance of the capacitor formed by the first electrode 51, the second electrode 52, and the third electrode 53, converts it into a voltage, and outputs it. That is, the capacity detection circuit 54 converts information for calculating the water level into a voltage and transmits the voltage to the control circuit Cont. The control circuit Cont calls the table from the memory Mem. Based on the voltage received from the capacity detection circuit 54, the control circuit Cont determines whether or not the water tank 2 is attached to the case 1 and the water tank 2 is attached to the case 1. If so, the water level of the water supply tank 2 is calculated.

  The control circuit Cont assumes a voltage threshold value, and determines that the water supply tank 2 is not attached to the case 1 when the voltage acquired from the capacity detection circuit 54 is lower than the threshold value. Also good. This threshold value can be a value between the capacitance Q1 and the capacitance Q2 shown in FIG. Even in the case where such control is performed, the effect of suppressing the occurrence of detection errors becomes higher when the values of the capacitance Q1 and the capacitance Q2 are far from each other.

  Next, a procedure of processing when steam cooking is performed will be described with reference to the drawings. When steam heating is selected in the input unit Sc, an operation input signal for performing the operation is sent to the control circuit Cont (step S11). In order to perform steam heating cooking, the control circuit Cont first determines whether or not the voltage V1 from the capacity detection circuit 54 is larger than the threshold value Vc in order to confirm whether or not the water supply tank 2 is mounted (step S1). S12). When the voltage V1 is smaller than the threshold value Vc (No in step S12), the control circuit Cont determines that the water supply tank 2 is not attached to the case 1 or is not attached correctly, and the water supply tank 2 is displayed on the display unit Mt. Is attached to the case 1 (step S13). Then, the steam heating process is terminated.

  When the voltage V1 from the capacity detection circuit 54 is larger than the threshold value Vc (Yes in step S12), the control circuit Cont determines that the water supply tank 2 is attached to the case 1, and the pump 4 and the heater Ht Driving is started and generation of steam is started (step S14). The voltage V1 from the capacitance detection circuit 54 is transmitted to the control circuit Cont at regular time intervals. In this state, the control circuit Cont calls a table for calculating the water level from the memory Mem (step S15).

  Then, the control circuit Cont calculates the current water level of the water supply tank 2 based on the voltage V1 from the capacity detection circuit 54 and the table for calculating the water level (step S16). The control circuit Cont determines whether the water level (water amount) currently stored in the water supply tank 2 is sufficient to continue the steam heating function (step S17). Note that whether or not the water level is sufficient is determined from the set temperature of the steam heating function, the current temperature of the article to be heated, the weight of the article to be heated, and the like.

  When the water level in the water supply tank 2 is insufficient (No in step S17), the control circuit Cont determines that it is impossible to continue the steam heating function and prompts the display unit Mt to supply water. Display is performed (step S18). The control circuit Cont stops the pump 4 and the heater Ht, stops the generation of steam (step S19), and ends the steam heating cooking.

  When sufficient water is stored in the water supply tank 2, when the water level is sufficiently high (Yes in step S17), the control circuit Cont determines whether or not to continue steam cooking (step S110). In addition, as a judgment of whether to continue the steam heating function, for example, the target has been achieved, for example, the time from the start of cooking has reached a predetermined time, the temperature of the article to be heated has reached the set temperature, etc. What is performed by detecting is mentioned. When steam cooking is continued (No in step S110), the process returns to step S16, and the steam heating cooking is continued while checking the water level of the water supply tank 2.

  When steam heating is not continued, that is, when steam cooking is completed (Yes in step S110), the control circuit Cont stops the pump 4 and the heater Ht, stops steam generation (step S19), and steam Finish cooking.

  As described above, the water level detection mechanism 5 according to the present invention has a configuration in which a simple change is made to one electrostatic detection sensor and is easy to manufacture. In addition, it can be used as both a mounting detection means for detecting the mounting of the water supply tank 2 by one water level detection mechanism 5 and a water level detection means for detecting the water level of water stored in the water supply tank 2. is there. As a result, the number of constituent members can be reduced and the control can be simplified.

  Further, in the water level detection mechanism 5 according to the present invention, since the electrode is not brought into contact with the water in the water supply tank 2, the water does not touch the electrode, so there is no fear of electric leakage, and rust and corrosion of the electrode can be suppressed. Therefore, it is possible to stably detect the installation of the water supply tank and detect the water level of the water supply tank 2 for a long period of time. Furthermore, since it can suppress that the component of an electrode melt | dissolves in the water used as the vapor | steam sprayed on the to-be-heated article which is a foodstuff, the bad influence to the human body by taking in the metal of an electrode can be prevented. In addition, even when the metal is harmless to the human body (living body), it is possible to prevent the appearance and taste (odor) of the article after heating from being changed, and to suppress the deterioration of the quality of the article.

  In the water level detection mechanism 5 according to the present invention, the first electrode 51 and the electrode 523 obtained by connecting the second electrode 52 and the third electrode 53 have the same or substantially the same length. However, the present invention is not limited to this. Further, the first electrode 51 and the electrode 523 connecting the second electrode 52 and the third electrode 53 are arranged close to each other in parallel, but need not necessarily be close to each other. Moreover, it is not necessary to be parallel if a non-contact state can be maintained.

  If the second electrode 52 and the third electrode 53 are electrically connectable, and the second electrode 52 and the third electrode 53 and the first electrode 51 are in an insulated state, the first electrode The shape of 51 is not particularly particular. Further, the second electrode 52 and the third electrode 53 are in contact with each other at the innermost portion in the insertion direction of the water tank 2, that is, the second electrode 52 is the inner surface of the case 1, and the third electrode 53 is the water tank 2. However, the present invention is not limited to this.

  7A to 7D are diagrams showing other examples of the first electrode, the second electrode, and the third electrode of the water level detection mechanism according to the present invention. In the water level detection mechanism 5A shown in FIG. 7A, the second electrode 52a is disposed below the third electrode 53a. Even in such a case, since the capacitance fluctuates as shown in FIG. 4, the presence or absence of the water supply tank 2 and the water level in the water supply tank are detected by the same detection method as described above. Is possible.

  In the water level detection mechanism 5B shown in FIG. 7B, the second electrode 52b and the third electrode 53b are arranged side by side in the direction along the water surface. Even in such a case, since the capacitance fluctuates as shown in FIG. 4, the presence or absence of the water supply tank 2 and the water level in the water supply tank are detected by the same detection method as described above. Is possible. Further, for example, when the third electrode 53b is disposed on a surface that rubs against the case 1 of the water supply tank 2 (side surface with respect to the sliding direction), the contact surface between the second electrode 52b and the third electrode 53b slides. Since the direction intersects the direction, the second electrode 52b and the third electrode 53b can be reliably brought into contact with each other.

  Further, FIG. 7C is a plan view of a case including a water level detection mechanism and a water supply tank. As shown in FIG. 7C, in the water level detection mechanism 5C, when the water supply tank 2 is stored in the case 1, the first electrode 51c is disposed on the surface facing the side surface with respect to the sliding direction of the water supply tank 2, The two electrodes 52c are disposed on a surface (the back surface) adjacent to the surface on which the first electrode 51c is disposed. The third electrode 53 c is disposed on the inner surface of the water supply tank 2. Even in such a case, since the capacitance fluctuates as shown in FIG. 4, the presence or absence of the water supply tank 2 and the water level in the water supply tank are detected by the same detection method as described above. Is possible. As shown in FIG. 7C, the first electrode 51c and the second electrode 52c may be disposed adjacent to the corners. By doing so, it is possible to suppress the capacitance of the capacitor formed by the first electrode 51c and the second electrode 52c from becoming too small to be detected by the capacitance detection circuit.

  In the water level detection mechanism 5D shown in FIG. 7D, the first electrode 51d and the second electrode 52d are housed inside the case 1d, and the third electrode 53d is placed inside the side wall of the water supply tank 2d. . And only the part which the 2nd electrode 52d and the 3rd electrode 53d contact is exposed so that it can contact electrically. With this configuration, the first electrode 51d and the second electrode 52d or the first electrode 51d and the electrode 523d connecting the second electrode 52d and the third electrode 53d are in electrical contact. It is possible to suppress. Even in such a case, since the capacitance fluctuates as shown in FIG. 4, the presence or absence of the water supply tank 2 and the water level in the water supply tank are detected by the same detection method as described above. Is possible.

  Moreover, in each embodiment mentioned above, when connecting a 2nd electrode and a 3rd electrode, the 2nd electrode shall be the upper part of a 3rd electrode, However, It is not limited to this, 3rd electrode May be arranged above the second electrode. By disposing the second electrode on the lower side, the degree of freedom in mounting the water level detection mechanism is increased.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this content. The embodiments of the present invention can be variously modified without departing from the spirit of the invention.

  The cooking device according to the present invention can be used for cooking for heating an article to be heated, such as cooking and heating of food or reheating of cooked food.

A Heat cooker Vp Steam generator 1 Case 2 Water supply tank 3 Water supply pipe 31 Valve 4 Pump 5 Water level detection mechanism 51 First electrode 52 Second electrode 53 Third electrode

Claims (8)

A water level detection mechanism for detecting the level of water stored in a water tank that is detachably attached to the case,
A first electrode;
A second electrode attached to the case in an insulated state from the first electrode;
A third electrode attached to the water tank so as to be electrically non-contact with water in the water tank and electrically connected to the second electrode when the water tank is attached to the case;
Capacitance detection means for detecting a capacitance of a capacitor composed of the first electrode and the second electrode or an electrode obtained by connecting the second electrode and the third electrode and the first electrode. A water level detection mechanism characterized by that.   The water level detection mechanism according to claim 1, wherein a connection electrode in which the second electrode and the third electrode are connected is disposed at a position where a water surface comes into contact with water when the water tank is filled.   The water level detection mechanism according to claim 1 or 2, wherein the third electrode is attached to a lower portion of the second electrode.   The water level detection mechanism according to any one of claims 1 to 3, wherein the second electrode is formed smaller than the third electrode.   The ratio of the size of the second electrode and the third electrode is the capacitance between the second electrode and the third electrode and the electrostatic capacity when the second electrode is connected to the third electrode. The water level detection mechanism according to claim 4, wherein a difference from the capacity is determined to be larger than a resolution of the capacity detection means.   The electrode connecting the second electrode and the third electrode is arranged such that one end is equal to or less than the lower limit of the water level and the other end is equal to or exceeds the upper limit of the water level. The water level detection mechanism according to any one of claims 1 to 5, wherein The water level detection mechanism according to any one of claims 1 to 6,
A water supply pipe including a pump for sucking out water from the water tank;
A steam generator, comprising: a heater for heating water supplied from the water supply pipe.   A cooking device comprising the steam generator according to claim 7.

Images