CN108548585B - Water level measuring device and method for water box and steam stove - Google Patents
Water level measuring device and method for water box and steam stove Download PDFInfo
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 281
- 238000000034 method Methods 0.000 title claims abstract description 36
- 238000001514 detection method Methods 0.000 claims abstract description 238
- 239000003990 capacitor Substances 0.000 claims abstract description 175
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- 239000005367 kimax Substances 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
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- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
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- G01F23/00—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm
- G01F23/22—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water
- G01F23/26—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields
- G01F23/263—Indicating or measuring liquid level or level of fluent solid material, e.g. indicating in terms of volume or indicating by means of an alarm by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water by measuring variations of capacity or inductance of capacitors or inductors arising from the presence of liquid or fluent solid material in the electric or electromagnetic fields by measuring variations in capacitance of capacitors
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Abstract
The embodiment of the invention provides water level measuring equipment for a water box, a method and a steam oven thereof, belonging to the field of household appliances, wherein the equipment comprises a circuit board, side of the circuit board is attached to the inner surface of the side wall of a water box installation part, or a plurality of detection capacitor plates which are arranged on the other side of the circuit board and are vertically arranged, each detection capacitor plate respectively forms a detection capacitor with the ground, and a detection device is used for applying a carrier signal to each detection capacitor, respectively detecting detection voltages at two ends of each detection capacitor according to different carrier frequencies of the carrier signals, and outputting an indication signal for indicating whether water exists or does not exist at the position of the water box corresponding to each detection capacitor respectively according to the amplitude increment of the detection voltage at two ends of each detection capacitor and the increment of the corresponding carrier frequencies.
Description
Technical Field
The invention relates to the field of household appliances, in particular to water level measuring equipment for a water box, a water level measuring method and a steam oven.
Background
The water box is an important component of the steam oven and provides a water source for the steam generator. The amount of water in the water box determines whether the cooking can be smoothly finished, and the insufficient amount of water can cause the steam heating to stop midway, thereby affecting the cooking effect.
At present, a water level detection method of a water box of a steam boiler mainly comprises a buoy type method and a probe type method, wherein the buoy type method and the probe type method are both contact type measurement methods.
The inventor of the present application finds out in the process of implementing the prior art: (1) both the float type and the probe type methods are contact type detection methods, that is, a floater or a metal probe must be placed in a water box, so that the floater or the metal probe is not easy to clean and easily pollutes a water source; (2) the buoy type method is difficult to complete multi-gear water level detection, and the detection result is rough; (3) the probe type method causes the water box to have complicated structural design, troublesome circuit lead and inconvenient taking out and adding water by users, and also increases the production and manufacturing cost.
Disclosure of Invention
It is an object of an embodiment of the present invention to provide water level measuring devices for water boxes, a method thereof, and a steam oven for solving or at least partially solving the above technical problems.
In order to achieve the purpose, water level measuring equipment for a water box is provided by the embodiment of the invention, and the water level measuring equipment comprises a circuit board, or a plurality of detection capacitor plates and a detection device, wherein the side of the circuit board is attached to the inner surface of the side wall of a water box mounting part, the or the plurality of detection capacitor plates are arranged on the other side of the circuit board and are vertically arranged, each detection capacitor plates respectively form a detection capacitor with the ground, the detection device is used for applying a carrier signal to each detection capacitor, respectively detects detection voltages at two ends of each detection capacitor according to different carrier frequencies of the carrier signals, and outputs an indication signal indicating that water exists or does not exist in the position of the water box corresponding to each detection capacitor respectively according to the amplitude increment of the detection voltages at two ends of each detection capacitor and the corresponding carrier frequency increment.
Optionally, for each detection capacitor, the detection device is configured to determine whether a ratio between an amplitude increment of a detection voltage across the detection capacitor and an increment of the corresponding carrier frequency is greater than a th preset value, output an indication signal that water is present at a position of the water box corresponding to the detection capacitor if the ratio is greater than the th preset value, and output an indication signal that water is absent at a position of the water box corresponding to the detection capacitor if the ratio is not greater than the th preset value.
Optionally, for each detection capacitor, the detection apparatus is configured to determine whether a ratio between an amplitude increment of a detection voltage across the detection capacitor and an increment of the corresponding carrier frequency is greater than a th preset value, output an indication signal that water is present at a position of the water box corresponding to the detection capacitor if the ratio is greater than the th preset value, determine whether the ratio is smaller than a second preset value if the ratio is not greater than the th preset value, the second preset value being smaller than the th preset value, output an indication signal that water is absent at a position of the water box corresponding to the detection capacitor if the ratio is not smaller than the second preset value, and output an indication signal that the water box is not mounted in place if the ratio is smaller than the second preset value.
Optionally, for each sense capacitor, the detection device is configured to determine the ratio by detecting a th sense voltage across the sense capacitor if the carrier frequency is th carrier frequency, detecting a second sense voltage across the sense capacitor if the carrier frequency is a second carrier frequency, detecting a third sense voltage across the sense capacitor if the carrier frequency is a third carrier frequency, and calculating the ratio according to the following equation:
wherein k is the ratio, f1Is said th frequency, f2Is said second frequency, f3Is the third frequency，Vim1Detecting the magnitude, V, of the voltage for said thim2Is the amplitude, V, of the second detection voltageim3Is the amplitude of the third detection voltage.
Optionally, for each sense capacitor, the th preset value is predetermined by measuring a maximum value of the ratio in the absence of water at the location of the water box corresponding to the sense capacitor plate, measuring a minimum value of the ratio in the presence of water at the location of the water box corresponding to the sense capacitor plate, and determining an average of the maximum value and the minimum value as the th preset value.
Optionally, the detection device detects the detection voltage using a transimpedance amplifier detection circuit corresponding to the detection capacitor , and the carrier signal is a high-frequency sinusoidal carrier signal.
Optionally, the apparatus comprises 4 said detection capacitor plates.
Optionally, when the water box is installed in place, a distance between the detection capacitor plate and the side wall of the water box adjacent to the detection capacitor plate is not greater than 2mm, and an area of the detection capacitor plate is 300mm2。
Correspondingly, the embodiment of the invention also provides steam ovens, which comprise the water level measuring equipment for the water box and a control device, wherein the control device is used for determining the water level state of the water box according to the indication signal output by the detection device.
Optionally, the steam oven further comprises: the control device is also used for controlling the display device to display the water level state of the water box; and the control device is also used for controlling the prompting device to give out a prompt under the condition that the water level of the water box reaches an early warning value and/or the water box is not installed in place.
Correspondingly, the embodiment of the invention also provides methods for the water level measuring device for the water box, wherein the method comprises the steps of applying a carrier signal to each detection capacitor, respectively detecting detection voltages at two ends of each detection capacitor aiming at different carrier frequencies of the carrier signal, and outputting an indication signal indicating that the water box has water or does not have water at the position respectively corresponding to each detection capacitor according to the amplitude increment of the detection voltage at two ends of each detection capacitor and the increment of the corresponding carrier frequency.
Optionally, for each detection capacitor, the method includes determining whether a ratio between an increment of an amplitude of a detection voltage across the detection capacitor and an increment of the corresponding carrier frequency is greater than a th preset value, if the ratio is greater than the th preset value, outputting an indication signal that water is present at a position of the water box corresponding to the detection capacitor, and if the ratio is not greater than the th preset value, outputting an indication signal that water is absent at a position of the water box corresponding to the detection capacitor.
Optionally, for each detection capacitor, the method includes determining whether a ratio between an amplitude increment of a detection voltage across the detection capacitor and an increment of the corresponding carrier frequency is greater than a preset value, if the ratio is greater than the preset value, outputting an indication signal that water is present at a position of the water box corresponding to the detection capacitor, if the ratio is not greater than the preset value, determining whether the ratio is less than a second preset value, which is less than the preset value, if the ratio is not less than the second preset value, outputting an indication signal that water is absent at a position of the water box corresponding to the detection capacitor, and if the ratio is less than the second preset value, outputting an indication signal that the water box is not mounted in place.
Optionally, for each sensed capacitance, the ratio is determined by detecting a th sensed voltage across the sensed capacitance if the carrier frequency is th carrier frequency, detecting a second sensed voltage across the sensed capacitance if the carrier frequency is a second carrier frequency, detecting a third sensed voltage across the sensed capacitance if the carrier frequency is a third carrier frequency, and calculating the ratio according to the following equation:
wherein k is the ratio, f1Is said th frequency, f2Is said second frequency, f3Is said third frequency, Vim1Detecting the magnitude, V, of the voltage for said thim2Is the amplitude, V, of the second detection voltageim3Is the amplitude of the third detection voltage.
By the technical scheme, non-contact water level detection can be realized, so that any processing design on the water box is not required, and the manufacturing cost is reduced; secondly, since the device does not need to be in contact with water, the problem of scale causing degradation of measurement accuracy is avoided.
Additional features and advantages of embodiments of the invention will be set forth in the detailed description which follows.
Drawings
The accompanying drawings are included to provide a further understanding of embodiments of the invention and are incorporated in and constitute a part of this specification , which together with the following detailed description serve to explain, but are not to limit, embodiments of the invention.
Fig. 1 illustrates a schematic configuration diagram of a water level measuring apparatus for a water bucket according to an embodiment of the present invention;
FIG. 2 shows a schematic diagram of a transimpedance amplifier detection circuit;
fig. 3a to 3b are schematic views showing installation positions of a water level measuring apparatus for a water bucket;
FIG. 4 shows a block diagram of a steam oven according to an embodiment of the invention, an
Fig. 5 shows a flow chart of a method of a water level measuring apparatus for a water bucket according to an embodiment of the present invention.
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating embodiments of the invention, are given by way of illustration and explanation only, not limitation.
It should be noted that all the directional indicators (such as up, down, left, right, front, and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. at a certain posture (as shown in the figure), and if the certain posture is changed, the directional indicator is changed accordingly.
Thus, a feature defined as "", "second" may explicitly or implicitly include at least of that feature.
Fig. 1 shows a schematic structural diagram of a water level measuring device for a water tank according to an embodiment of the present invention , as shown in fig. 1, the present invention provides water level measuring devices for a water tank 10, which can be applied to any household electrical appliance having a water tank or a similar water container, such as a steam oven, a hot water bottle, a water heater, a water dispenser, a steamer, a dehumidifier, a humidifier, an air purifier, a coffee machine, a smart water cup, etc. the present invention is illustrated by taking a steam oven as an example, the device may include a circuit board 30, a side of which is attached to an inner surface of a side wall of a water tank mounting portion 20, or more detection capacitor plates 40 arranged vertically on another side of the circuit board 30, each detection capacitor plate 40 constituting a detection capacitor with the ground for each 363, and a detection device 50 for applying a carrier signal to the detection capacitors for each , detecting the amplitude values of the detection capacitors at two ends of each detection capacitor for different carrier frequencies of the carrier signal, detecting the amplitude values at two ends of the detection capacitors for each detection capacitor , and the detection capacitors for each carrier frequency of the detection capacitors corresponding to the detected water tank 7377, and the detected water level, so that the detected capacitors corresponding to the detected capacitors for each carrier frequency of the water tank may be determined by detecting capacitors corresponding to the detection capacitors for each carrier frequency of the detection capacitors corresponding to the water tank 7372, 6853, and the detected water tank, so that the detected water tank, the detected water tank may be detected water tank, and the detected capacitors for detecting capacitors corresponding to the detected water tank, and the.
The water level measuring equipment of the water box provided by the embodiment of the invention can realize non-contact water level measurement, and can prevent various components from being splashed with water or damaged due to collision.
The water box 10 is used to supply water to a steam generator of a steam boiler, and in order to measure the water level of the water box, the portion of the wall of the water box 10 adjacent to each sensing capacitor plate 40 should be flat and the material should be insulating or non-conductive, for example, the water box 10 may be a plastic water box.
The height of the circuit board 30 can be larger than that of the water box 10, the side of the circuit board 30 can be adhered to the inner surface of the side wall of the water box mounting part 20 by adhesive, the detection capacitor plate 40 can be, for example, a copper foil, the detection capacitor plate 40 can be vertically arranged on the circuit board uniformly along the height direction of the water box, or can be non-uniformly arranged according to needs, the area of the detection capacitor plate can be preferably 300mm2. Further, the circuit Board 30 may be a PCB (printed circuit Board) Board, but the embodiment of the present invention is not limited thereto.
The shape of the sensing capacitor plate 40 may be a rectangular parallelepiped, the number and the installation position of the sensing capacitor plates 40 may be determined by the number of required water level sensing steps, for example, if four steps are required, the four steps are 25%, 50%, 75% and 100%, respectively, the circuit board may be covered with 4 sensing capacitor plates 40, and the 4 sensing capacitor plates 40 correspond to 25%, 50%, 75% and 100% of the height of the water tank from low to high, respectively. Or, conversely, the gear positions may be set according to the number and positions of the detection capacitor plates 40, for example, if the circuit board is covered with 4 detection capacitor plates 40, and the 4 detection capacitor plates 40 correspond to 25%, 50%, 75% and 100% of the height of the water box from low to high, four gear positions may be set, which are 25%, 50%, 75% and 100%, respectively.
For each detection capacitor, the detection device 50 can determine whether water exists or not at the position corresponding to the detection capacitor of the water box 10 according to the ratio between the amplitude increment of the detection voltage at the two ends of the detection capacitor and the increment of the corresponding carrier frequency, specifically, if the ratio between the amplitude increment of the detection voltage at the two ends of the detection capacitor and the increment of the corresponding carrier frequency is greater than th preset value, it can be determined that water exists at the position corresponding to the detection capacitor of the water box 10, and a water indication signal exists at the position corresponding to the detection capacitor of the water box 10, otherwise, it can be determined that water does not exist at the position corresponding to the detection capacitor of the water box 10, and an indication signal indicating that water does not exist at the position corresponding to the detection capacitor of the water box 10, wherein the th preset value can be a predetermined value, and the th preset value can be different for the detection capacitors formed by different detection capacitor plates.
The manner in which the detection device 50 determines whether water is present or absent at the location corresponding to the detection capacitor 10 based on the ratio between the increment of the amplitude of the detection voltage across the detection capacitor and the corresponding increment of the carrier frequency is theoretically verified, since the detection voltage is small, the detection device 50 may amplify the detection voltage using a transimpedance amplifier detection circuit corresponding to the detection capacitor to determine the detection voltage and the reference voltage, respectively, and the carrier signal applied to the detection capacitor may be a high-frequency sinusoidal carrier signal.
Detection capacitor C formed by capacitor plate and earth ground for detection of any capacitor iFor example, the capacitance of the detection capacitor is represented by XiI is the number of the detection capacitor, i is 1,2, …, n is the number value of the detection capacitor. Fig. 2 shows a schematic diagram of a transimpedance amplifier detection circuit. In FIG. 2, VcIs a high-frequency sinusoidal carrier signal whose amplitude and frequency are respectively denoted by V0And f; the output voltage of the trans-impedance amplifier is Vi，ViIn order to amplify the voltage output by the voltage at two ends of the detection capacitor, the inventionIn the embodiment, the voltage output by the trans-impedance amplifier is used as the detection voltage at two ends of the detection capacitor; cfFor feedback capacitance, CfCapacity resistance of Xf；RfAs a feedback resistance, CpiIs a parasitic capacitance; cpiCapacity resistance of XpiFor fixed circuit structure and layout wiring, parasitic capacitance CpiAs a fixed value, there may be:
wherein,
the following equations (1) and (2) can be derived:
wherein,
where ω is the angular frequency of the current, ε0Is a vacuum dielectric constant of ∈riThe relative dielectric constant of air is close to 1, and the dielectric constant of water is about 81.5, which is the basis of the capacitive water level detection theory. S is the area of the capacitor plate to be detected, diTo detect the spacing of the capacitors. Since 1 > ω RfCfEquation (3) can be simplified as:
then ViAmplitude V ofimComprises the following steps:
considering that the trans-impedance amplifier will existAt mismatched DC voltage VpiThus, there are:
each detection capacitor plate is respectively connected with trans-impedance amplifier detection circuits, and due to different parameters such as the length of a lead in the circuit, the mismatched direct current voltage V in the formula (7) is obtained for different detection capacitorspiIt will also be different if the voltage amplitude V of the transimpedance amplifier output is simply usedimIf the water is present or not at the position corresponding to the water box, erroneous judgment is easily caused, and the measurement accuracy is reduced. Therefore, the embodiment of the invention introduces a slope comparison method to eliminate the mismatched direct-current voltage VpiDifference pair V ofimThe resulting effect.
Equation (7) shows the frequency f of the high frequency sinusoidal carrier signal and the amplitude V of the sense voltageimIs a linear relationship, wherein the slope kiComprises the following steps:
equation (8) shows that the slope kiAnd relative dielectric constant εriAlso a linear relationship. Due to V0、Rf、ε0、S、diAnd CpiAre all constant, and therefore by measuring the slope kiThe relative dielectric constant ε can be determinedriTo determine whether the dielectric in the capacitor is water or air. In summary, it is possible that the detecting device 50 determines whether water is present or absent at a position corresponding to the detection capacitor of the water tank 10 according to a ratio between an increase in amplitude of the detection voltage across the detection capacitor and an increase in the carrier frequency corresponding thereto.
Further , since the relative dielectric constant of air is close to 1 and the relative dielectric constant of water is about 81.5, the slope k is determined according to equation (8) when there is water or no water at the position of the water box corresponding to the detection capacitoriThe size difference of (2) is large. Therefore, by calculating the magnitude of the slopeThe slope can be determined according to the ratio of the amplitude increment of the voltage output by the transimpedance amplifier to the frequency increment of the corresponding high-frequency sinusoidal carrier signal, specifically, if the ratio is greater than preset value, the water in the position corresponding to the detection capacitor can be determined, otherwise, the water in the position corresponding to the detection capacitor can be determined.
In the actual measurement process, because the slope needs to be calculated, the carrier frequency of the high-frequency sinusoidal carrier signal needs to be changed at least times to detect the voltage output by the transimpedance amplifier at different carrier frequencies, so as to determine the slope according to the ratio between the increment of the amplitude of the voltage and the increment of the corresponding carrier frequency, and therefore, the slope may also be the ratio in the embodiment of the present invention1、f2、f3. Alternatively, the frequencies of the high-frequency sinusoidal carrier signals can be set to 200kHz, 600kHz and 1000kHz respectively, and then the amplitude V of the voltage signal output by the transimpedance amplifier under different carrier signals is testedim1、Vim2And Vim3。
In particular, for detecting the capacitance CiSet to th carrier frequency f at carrier frequency1In the case of (1), the capacitance C is detected and detectedi th detection voltage of the output of the connected trans-impedance amplifier, carrier frequency f set at th carrier frequency2In the case of (1), the capacitance C is detected and detectediA second detection voltage output from the connected transimpedance amplifier, a carrier frequency f set at 3In the case of (1), the capacitance C is detected and detectediThe third detection voltage output by the connected trans-impedance amplifier, and then the slope k is calculated according to the following formulai(also may be a ratio k)i)：
Wherein, Vim1Detecting the magnitude, V, of the voltage for said thim2Is the amplitude, V, of the second detection voltageim3Is the amplitude of the third detection voltage.
K calculated according to the formula (9)iAnd th preset value ki0In contrast, if kiGreater than ki0Then, the water box and the detection capacitor C are judgediThe corresponding position has water, otherwise, the position is judged to be anhydrous. For different detection capacitances, kiAnd th preset value ki0May be different. The execution process of setting the carrier frequency to different values and detecting the output voltage of each transimpedance amplifier in the case where the carrier frequency is different values by the detection means can be completed in a very short time, which does not affect the detection accuracy of the water level of the water box.
Because there may be a small processing error between the electrode areas and the capacitor spacings corresponding to the detection capacitor electrode plates disposed at different positions, and the layout and wiring of the detection circuits corresponding to the detection capacitors at different positions are different, the parameter is not completely , which will cause the ratio k corresponding to different detection capacitors to be obtained by step according to formula (8)iIt may be different, so that the th preset value corresponding to each detection capacitor needs to be predetermined.
Detecting capacitance C for a certain iThe th preset value corresponding to the detected capacitance can be predetermined according to the following way:
(1) in the water-free state, the mounting deviation of the water box is considered, for example, the maximum value and the minimum value of the mounting clearance between the water box and the detection capacitor polar plate, the shaking process of the water box and the like are considered, and then the water box and the detection capacitor C under different conditions are respectively measurediSelecting the maximum value k of the corresponding ratiosimax. In general, in order to avoid the influence of the temperature deviation, the water temperature may be controlled in the range of 0 to 60 ℃ in this step;
(2) in the presence of water, taking into account the deviation of the water box, e.g. the installation space between the water box and the detection capacitor plateMaximum and minimum values of the gap, shaking process of the water box, etc., and then measuring the capacitance C and the detection capacitance C under different conditions respectivelyiSelecting the maximum value k of the corresponding ratiosimin. In general, in order to avoid the influence of the temperature deviation, the water temperature may be controlled in the range of 0 to 60 ℃ in this step;
(3) determining an average of the maximum and minimum values as a detected capacitance CiCorresponding th preset value ki0Namely: k is a radical ofi0＝(kimax+kimin) In the embodiment of the present invention, i is the number of the detection capacitor, i is 1,2, …, n, and n is the magnitude of the detection capacitor.
In the above manner, the th preset value is an average value between the maximum value and the minimum value, and it is understood that the th preset value may be any value between the maximum value and the minimum value, and the embodiment of the present invention is not limited specifically.
Taking 4 detection capacitor plates and 1 reference capacitor plate arranged on the circuit board as an example, wherein the 4 detection capacitor plates respectively correspond to 25%, 50%, 75% and 100% of the height of the water box from low to high, and the areas of the 4 detection capacitor plates are the same and are 3mm2Using the above approach, the th preset value corresponding to the sensing capacitance formed by each sensing capacitor plate can be determined, as shown in the following table,
TABLE 1 test results of th preset values corresponding to different detection capacitors
| 25％ | 50％ | 75％ | 100％ | |
| kimax | 493 | 542 | 610 | 627 |
| kimin | 600 | 657 | 749 | 780 |
| ki0 | 546.5 | 599.5 | 679.5 | 703.5 |
It can be known from table 1 that, in the presence and absence of water, the difference between the slope calculated according to the ratio of the amplitude increment output by the transimpedance amplifier to the corresponding carrier frequency increment is large, and the -th preset values corresponding to the detection capacitors at different positions are preset respectively, so that the influence of the direct-current bias voltage, the processing error of the capacitor plate and the influence caused by the installation deviation of the water box can be effectively reduced, and the detection sensitivity is greatly improved.
The detection device used in the embodiment of the present invention may be a dedicated IC chip, which is programmable, may have 11 to 22 capacitance detection channels, which may be connected to a plurality of capacitance plates, the output signal may be output through an I/O output port or an IIC digital interface, and may indicate a signal indicating presence of water at a high level and indicate absence of water at a low level, taking as an example that 4 detection capacitance plates are provided on a circuit board, wherein the 4 detection capacitance plates correspond to 25%, 50%, 75% and 100% of the height of a water cartridge, respectively, from low to high, and 4I/O output ports are used to output an indication signal indicating presence of water or absence of water at a position where the water cartridge corresponds to each detection capacitance, respectively, at the time of measurement, a carrier frequency of a high frequency sinusoidal carrier signal applied to the dedicated IC chip is set, the high frequency sinusoidal carrier signal is applied to each detection capacitance, the chip detects detection voltages of each detection capacitance at different carrier frequencies, and detects a capacitance for each , calculates a detection voltage corresponding to each detection capacitance per detection capacitance according to the magnitude of an increment of its detection voltage and a corresponding carrier frequency, if the difference is greater than a slope of a corresponding to a preset value, indicates that the slope of , the corresponding to a high water level, and if the signal is lower than a preset value, the high level, the water level, the high level indicates that "1111%" 0 ", otherwise, the water level" indicates no water level "is lower than 0", and "00001", and indicates no water "00001", otherwise, the high ", the high level is lower than" 00001 ", the high level, indicates no water level, or" 00001 ", and.
Fig. 3a to 3b are schematic views showing installation positions of a water level measuring apparatus for a water cartridge, as shown in fig. 3a to 3b, the water cartridge 10 is a movable water cartridge which can be horizontally drawn out from the water cartridge installation section 20 and can be horizontally pushed into the water cartridge installation section 20, the water level measuring apparatus 100 for a water cartridge can be installed on an inner surface of any side walls of the water cartridge installation section 20 except for upper and lower side walls, for example, on an inner surface of a rear side wall of the water cartridge installation section 20 (as shown in fig. 3 a), or on an inner surface of any side wall of left and right side walls (on left and right sides in a movable direction of the water cartridge 10) of the water cartridge installation section 20 (as shown in fig. 3 b), in a case where the water cartridge 10 is installed in place, a distance between the water level measuring apparatus 100 for a water cartridge and a side wall adjacent to the water level measuring apparatus 100 for a water cartridge is not more than 2mm, and since a detection capacitor is disposed on a circuit board, a detection sensitivity can be also restricted to improve a horizontal detection sensitivity of not more than 2 mm.
Therefore, if the detection device detects that the water box is not water at the position corresponding to the detection capacitor, is needed to judge whether the water box is really water-free or not.
Specifically, the capacitance C is detected for every iJudging and detecting the capacitance CiCorresponding slope kiWhether or not it is larger than the detection capacitor CiCorresponding th preset value ki0Wherein the slope kiAccording to the detected capacitance CiAnd the corresponding carrier frequency increment. If the slope kiGreater than the th preset value ki0And outputting an indication signal that water exists at the position of the water box corresponding to the detection capacitor. If the slope k is determinediIs not greater than the th preset value ki0Then the slope k can be continuously determinediIf it is less than the second preset value, if the slope kiAnd if the water level is not less than the second preset value, the water box can be determined to be anhydrous at the position corresponding to the detection capacitor, and an indication signal indicating that the water is anhydrous is output. If the slope kiAnd if the water box is smaller than a second preset value, outputting an indication signal that the water box is not installed in place, wherein the second preset value is smaller than the th preset value.
The second preset value is determined in a manner similar to that of the th preset value described above, and when the water box is not mounted in place, the difference between each detected voltage and the reference voltage is detected, and the largest difference is selected from these differences as the second preset value.
The detection device can output an indication signal indicating that the water box is not installed in place under the condition that any slope corresponding to the detection capacitors are smaller than the second preset value, for example, ports for outputting the indication signal indicating whether the water box is installed in place can be separately added when the I/O output port is used for outputting the signal.
Through the embodiment, the water level measuring equipment for the water box provided by the embodiment of the invention can execute non-contact water level detection, so that the water box does not need to be processed and designed, and the manufacturing cost is reduced; secondly, the equipment does not need to be contacted with water, so that the problem of measurement accuracy degradation caused by scale is avoided; finally, the advanced frequency conversion slope comparison method is adopted for water level judgment, the influence caused by mismatch direct current voltage, parasitic capacitance, processing error, installation deviation and the like of the operational amplifier can be effectively inhibited, and the water level judgment precision is higher.
Fig. 4 shows a block diagram of a steam oven according to an embodiment of the present invention, as shown in fig. 4, the embodiment of the present invention further provides steam ovens, which may include a water level measuring apparatus 100 for a water cartridge according to any embodiment of the present invention, and a control device 200, which may be used to determine a water level state of the water cartridge according to an indication signal output from a detecting device of the apparatus 100, for example, taking an example of providing 4 detecting capacitor plates on a circuit board, wherein the 4 detecting capacitor plates respectively correspond to 25%, 50%, 75% and 100% of the height of the water cartridge from low to high, if a level signal is "1111" is received, the water level in the water cartridge may be determined to be 100%, if a level signal is "0001" is received, the water level in the water cartridge may be determined to be higher than 25% and lower than 50%, etc., wherein a high level "1" indicates that water is present, and a low level "0" indicates that no water is present.
additionally, the steam oven may further include a display device and/or a prompt device, wherein the control device may further control the display device to display the water level state of the water tank, and control the prompt device to give a prompt in case the water level state of the water tank reaches an early warning value and/or the water tank is not mounted in place.
The above embodiment is described by taking a steam oven as an example, but it can be understood that the water level measuring device for a water box provided by the embodiment of the present invention can be applied to any other household appliances having a water box or a similar water container, such as an electric hot water bottle, a water heater, a water fountain, a steamer, a dehumidifier, a humidifier, an air purifier, a coffee maker, an intelligent water cup, and the like.
FIG. 5 is a flow chart illustrating a method of a water level measuring apparatus for a water bucket according to an embodiment of the present invention , as shown in FIG. 5, the embodiment of the present invention further provides methods of water level measuring apparatuses for water buckets according to any embodiment of the present invention, which may include a step S51 of applying a carrier signal to each of the sensing capacitors, a step S52 of detecting sensing voltages across each of the sensing capacitors for different carrier frequencies of the carrier signal, respectively, and a step S53 of outputting an indication signal indicating whether water is present or absent at positions of the water bucket corresponding to each of the sensing capacitors, respectively, according to an amplitude increment of the sensing voltage across each of the sensing capacitors and an increment of the carrier frequency, respectively.
The specific working principle and benefits of the method for measuring the water level of the water box provided by the embodiment of the invention are similar to those of the water level measuring device provided by the embodiment of the invention, and the detailed description is omitted here.
Although the embodiments of the present invention have been described in detail with reference to the accompanying drawings, the embodiments of the present invention are not limited to the details of the above embodiments, and various simple modifications can be made to the technical solutions of the embodiments of the present invention within the technical idea of the embodiments of the present invention, and the simple modifications all belong to the protection scope of the embodiments of the present invention.
It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. In order to avoid unnecessary repetition, the embodiments of the present invention do not describe every possible combination.
Those skilled in the art will appreciate that all or part of the steps in the method according to the above embodiments may be implemented by instructing the relevant hardware through a program, where the program is stored in storage media, and includes several instructions for causing a single chip microcomputer, a chip or a processor (processor) to execute all or part of the steps in the method according to the embodiments of the present application.
In addition, any combination of various different implementation manners of the embodiments of the present invention is also possible, and the embodiments of the present invention should be considered as disclosed in the embodiments of the present invention as long as the combination does not depart from the spirit of the embodiments of the present invention.
Claims (14)
1, A water level measuring device for a water box, characterized in that the device comprises:
a circuit board, wherein the side of the circuit board is attached to the inner surface of the side wall of the water box mounting part;
or a plurality of detection capacitor plates which are arranged vertically on the other side of the circuit board, wherein each detection capacitor plates respectively form a detection capacitor with the ground, and
and the detection device is used for applying a carrier signal to each detection capacitor, respectively detecting detection voltages at two ends of each detection capacitor aiming at different carrier frequencies of the carrier signal, and outputting an indication signal indicating that water exists or does not exist at the position of the water box corresponding to each detection capacitor according to the amplitude increment of the detection voltage at two ends of each detection capacitor and the increment of the corresponding carrier frequency.
2. The apparatus of claim 1, wherein for each said detected capacitance, said detecting means is configured to:
judging whether the ratio of the amplitude increment of the detection voltage at the two ends of the detection capacitor to the corresponding increment of the carrier frequency is larger than preset value or not;
if the ratio is larger than the th preset value, outputting an indication signal that water exists at the position of the water box corresponding to the detection capacitor, and
and if the ratio is not greater than the th preset value, outputting an indication signal that the water box is not water at the position corresponding to the detection capacitor.
3. The apparatus of claim 1, wherein for each said detected capacitance, said detecting means is configured to:
judging whether the ratio of the amplitude increment of the detection voltage at the two ends of the detection capacitor to the corresponding increment of the carrier frequency is larger than preset value or not;
if the ratio is larger than the th preset value, outputting an indication signal that water exists at the position of the water box corresponding to the detection capacitor;
if the ratio is not greater than the th preset value, judging whether the ratio is smaller than a second preset value, wherein the second preset value is smaller than the th preset value;
if the ratio is not smaller than the second preset value, outputting an indicating signal that no water exists at the position corresponding to the detection capacitor of the water box; and
and if the ratio is smaller than the second preset value, outputting an indication signal that the water box is not installed in place.
4. A device according to claim 2 or 3, wherein for each detected capacitance, the detection means is arranged to determine the ratio in accordance with the following steps:
detecting a th detection voltage across the detection capacitor in the case where the carrier frequency is an th carrier frequency;
detecting a second detection voltage at two ends of the detection capacitor under the condition that the carrier frequency is a second carrier frequency;
detecting a third detection voltage at two ends of the detection capacitor under the condition that the carrier frequency is a third carrier frequency; and
calculating the ratio according to the following formula:
wherein k is the ratio, f1For said th carrier frequency, f2For the second carrier frequency, f3Is the third carrier frequency, Vim1Detecting the magnitude, V, of the voltage for said thim2Is the amplitude, V, of the second detection voltageim3Is the amplitude of the third detection voltage.
5. The apparatus of claim 2 or 3, wherein for each detected capacitance of , the preset value is predetermined according to:
measuring the maximum value of the ratio under the condition that no water exists at the position corresponding to the water box and the detection capacitor plate;
measuring the minimum value of the ratio under the condition that water exists at the position corresponding to the water box and the detection capacitor plate; and
and determining the average value of the maximum value and the minimum value as the th preset value.
6. The apparatus of claim 1, wherein the detection device detects the detection voltage using a transimpedance amplifier detection circuit corresponding to the detection capacitor , and wherein the carrier signal is a high frequency sinusoidal carrier signal.
7. The apparatus of claim 1, comprising 4 of said sensing capacitor plates.
8. The apparatus of claim 1, wherein with the water box in place, the distance between the sensing capacitor plate and the side wall of the water box adjacent to the sensing capacitor plate is no greater than 2mm, and the area of the sensing capacitor plate is 300mm2。
Steam oven of the kind , characterized in that the steam oven comprises:
the water level measuring apparatus for a water bucket according to any of claims 1 to 8, and
and the control device is used for determining the water level state of the water box according to the indication signal output by the detection device.
10. The steam oven of claim 9, further comprising:
the control device is also used for controlling the display device to display the water level state of the water box; and/or
And the control device is also used for controlling the prompting device to send out a prompt under the condition that the water level of the water box reaches an early warning value and/or the water box is not installed in place.
A method of water level measuring device for water cartridges of claim 11, , wherein the water level measuring device is the water level measuring device for water cartridges of any of claims 1 to 8 of claim , the method comprising:
applying a carrier signal to each of the detection capacitors ;
detecting detection voltages across the detection capacitors for each detection capacitors for different carrier frequencies of the carrier signal, respectively, and
outputting an indication signal indicating the presence or absence of water at the water box at the position corresponding to each detection capacitor respectively according to the increment of the amplitude of the detection voltage across each detection capacitor and the corresponding increment of the carrier frequency.
12. The method of claim 11, wherein for each detected capacitance, the method comprises:
judging whether the ratio of the amplitude increment of the detection voltage at the two ends of the detection capacitor to the corresponding increment of the carrier frequency is larger than preset value or not;
if the ratio is larger than the th preset value, outputting an indication signal that water exists at the position of the water box corresponding to the detection capacitor, and
and if the ratio is not greater than the th preset value, outputting an indication signal that the water box is not water at the position corresponding to the detection capacitor.
13. The method of claim 11, wherein for each detected capacitance, the method comprises:
judging whether the ratio of the amplitude increment of the detection voltage at the two ends of the detection capacitor to the corresponding increment of the carrier frequency is larger than preset value or not;
if the ratio is larger than the th preset value, outputting an indication signal that water exists at the position of the water box corresponding to the detection capacitor;
if the ratio is not greater than the th preset value, judging whether the ratio is smaller than a second preset value, wherein the second preset value is smaller than the th preset value;
if the ratio is not smaller than the second preset value, outputting an indicating signal that no water exists at the position corresponding to the detection capacitor of the water box; and
and if the ratio is smaller than the second preset value, outputting an indication signal that the water box is not installed in place.
14. A method according to claim 12 or 13, characterized in that for every detected capacitances, the ratio is determined according to the following steps:
detecting a th detection voltage across the detection capacitor in the case where the carrier frequency is an th carrier frequency;
detecting a second detection voltage at two ends of the detection capacitor under the condition that the carrier frequency is a second carrier frequency;
detecting a third detection voltage at two ends of the detection capacitor under the condition that the carrier frequency is a third carrier frequency; and
calculating the ratio according to the following formula:
wherein k is the ratio, f1For said th carrier frequency, f2For the second carrier frequency, f3Is the third carrier frequency, Vim1Detecting the magnitude, V, of the voltage for said thim2Is the amplitude, V, of the second detection voltageim3Is the amplitude of the third detection voltage.
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