CN110117890A - A kind of liquid level detection device, liquid-level detecting method and washing machine - Google Patents

Abstract

The invention discloses a liquid level detection device, which belongs to the field of liquid level detection and solves the problem of inaccurate and unreliable liquid level detection in the prior art. The technical solution for solving this problem mainly includes a liquid level sensor and a detection chip, a liquid level The level sensor sends signals to the detection chip. The liquid level sensor is a capacitive diaphragm sensor. The liquid level sensor is provided with multiple detection terminals. The detection terminals are arranged on the outer wall of the liquid container. The multiple detection terminals are arranged along the height direction of the liquid container. The detection areas of two adjacent detection terminals in the height direction are overlapped, and each detection terminal is connected to the I/O pin of the detection chip one-to-one. The invention is mainly used to improve the accuracy of liquid level detection. In addition, the present invention also provides a liquid level detection method using the above liquid level detection device. A washing machine is also provided, which adopts the above-mentioned liquid level detection device and can adopt the above-mentioned liquid level detection method.

Description

Liquid level detection device, liquid level detection method and washing machine

technical field

The invention relates to liquid level detection and household appliances, in particular to a liquid level detection device, a liquid level detection method using the liquid level detection device, and a washing machine equipped with the liquid level detection device and using the liquid level detection method.

Background technique

1. The current fully automatic washing machines basically use differential pressure water level sensors to automatically control the water level of the washing machine. The principle of the differential pressure water level sensor is to cause pressure changes in the air pressure pipe through changes in water level, which in turn causes sensor coil inductance. Change, thereby changing the output frequency of the sensor to achieve water level detection. However, the accuracy of this differential pressure water level sensor is poor, and the reason for the error is not only the tolerance of the electronic components (LRC) that constitute its detection circuit, but also the mechanical structure of the water level sensor itself (such as air pressure tube, sensor film), etc. Influence, and the sensor film must have a certain degree of wear and tear with the repeated actions of the time of use, and the detection error of the water level will increase over time.

2. In the prior art, a capacitive water level detection device is also used. For example, the patent No. ZL01231098.0 discloses a capacitive water level detection device. The device is to vertically place the metal conductor covering the insulating layer in the water tank. As the water level changes, a variable capacitance will be generated between the sensor and the water, and the control unit will convert the variable capacitance value into a variable electrical signal to control the water level in the water tank. This water level detection device needs to place the sensor in the water tank, and because the inner cylinder of the washing machine needs to place laundry, the device is not particularly suitable for the washing machine.

3. Patent No. 200810000761.1 also discloses a capacitive water level detection device. The device uses a capacitive sensor composed of a PCB substrate and a metal sheet to detect the water level in the bucket of the washing machine. The metal sheet is closely attached to the bucket of the washing machine. It can sense the change of water level and change its capacitance value. Through a control unit, detect and process the capacitance value of the capacitive sensor to calculate the water level. High and low to control the water level. The sensor senses the tiny strain on the outer wall of the bucket caused by the increase or decrease of water, so that the distance between the metal sheet and the PCB substrate also changes slightly. Due to the change of the distance, the capacitance value also increases. Change accordingly. Therefore, the thickness of the bucket wall of the washing machine has a certain limitation on the sensing ability of the sensor. When forming, there is a certain error in the thickness of the upper and lower parts of the same bucket, and there is also a certain error in the wall thickness of different buckets. affect the detection accuracy of the sensor. In addition, the bucket of the washing machine is a plastic product. With the increase of use time, it is vulnerable to the deformation of the plastic bucket due to the aging of the plastic bucket, resulting in inaccurate detection. Secondly, the metal sheet is directly exposed to the air, and it is easy to adhere to dirt and dust, which will cause the capacitance value Not precise.

4. In addition, more and more washing machines have developed and used detergent automatic delivery systems, and most of them use liquid level probes to detect the remaining amount of detergent in the detergent storage box. The application number is 201120479906.8 which discloses a pair of The probe detects the remaining amount of detergent and alarms when the remaining amount of detergent is the lowest. The application number is 201520725062.9, which discloses the multi-stage detection of detergent liquid level by using several conductive metal rods of different lengths. Existing technologies all use liquid level probes, but such metal probes may be ionized or easily corroded and rusted in the detergent environment for a long time, and different laundry detergents, their composition, concentration, etc. Different, these will affect the conductivity between the two probes, thereby affecting the misjudgment of the detergent level.

Contents of the invention

One of the objectives of the present invention is to provide a liquid level detection device to improve the accuracy of liquid level detection.

In order to achieve the above object, the present invention adopts the following technical solutions: a liquid level detection device, including a liquid level sensor and a detection chip, the liquid level sensor sends a signal to the detection chip, the liquid level sensor is a capacitive diaphragm sensor, and the liquid level sensor is designed There are a plurality of detection terminals, the detection terminals are arranged on the outer wall of the liquid container, and the plurality of detection terminals are arranged along the height direction of the liquid container, and the detection areas of two adjacent detection terminals in the height direction are overlapped, and each detection terminal is connected to the The I/O pins of the detection chip are connected one-to-one.

As a preferred solution, the liquid level sensor is pasted or molded on the outer wall of the liquid container.

After adopting the above-mentioned technical solution, the present invention has the following advantages: firstly, the present embodiment utilizes the induced capacitance to detect the liquid level, and the detection terminal is arranged on the outer wall of the liquid container, which is isolated from the liquid, has a simple structure, high waterproofness, and is also It is easy to install and set up, and it is also easy to prevent dust. It can be installed independently in a relatively sealed space; secondly, using multiple detection terminals for segment detection, the detection areas of two adjacent detection terminals in the height direction The height of the liquid level detected by each detection terminal is different. Compared with an overall continuous detection terminal, the detection range base of each detection terminal is reduced. Under the same process conditions, the deviation ratio of the detection results is the same. Because each detection The base of the detection range of the terminal is reduced, so the deviation value of the detection result is reduced, thereby improving the accuracy of the detection and calculation of the entire liquid level sensor; third, in the detection process, the detection chip first obtains the capacitance equivalent of the liquid level sensor when the liquid container is empty value Cp, when the liquid container is filled with liquid, the detection chip obtains the capacitance equivalent value Cxi of each detection terminal, and all detection terminals overlapping with the liquid in the height direction will generate induced capacitance, record the capacitance of all detection terminals Inductive capacitance, among all detection terminals that generate inductive capacitance, calculate the inductive capacitance of all detection terminals below the detection terminal at the highest position with the rated value, and calculate the inductive capacitance of the detection terminal at the highest position with the real-time value. Since there is no deviation in the rated value, the actual deviation value is only produced by one detection terminal, which has been significantly reduced, greatly improving the detection accuracy.

One of the objectives of the present invention is to provide a liquid level detection method to improve the accuracy of liquid level detection.

The present invention also provides a liquid level detection method. Using the above-mentioned liquid level detection device, the detection chip first obtains the capacitance equivalent value Cp of the liquid level sensor when the liquid container is empty, and when the liquid container is filled with liquid, the detection chip obtains The capacitance equivalent value Cxi of each detection terminal, the sum of the capacitance equivalent values of all detection terminals is Cx=ΣCxi, all detection terminals overlapping with the liquid in the height direction will generate inductive capacitance, record the inductance of all detection terminals The sum of the generated capacitance Cs, and then subtract the sum of the induced capacitance value Ct of each detection terminal overlapping with the previous detection terminal, and calculate A according to the formula Cx=Cp+Cs-Ct, Cs=εo×εr×A/D, Then calculate the liquid level height of the liquid according to the area formula, where:

εo = permittivity of free space;

εr = insulation constant of liquid level sensor;

A = the overlapping area of the liquid and the detection terminal;

D = Thickness of detection terminal.

As a preferred solution, a conversion circuit is provided between the detection chip and the liquid level sensor, the conversion circuit converts the capacitance equivalent value Cxi of each detection terminal into a digital key value, and the detection chip stores the digital key value.

The present invention also provides a liquid level detection method. Using the above-mentioned liquid level detection device, the detection chip first obtains the capacitance equivalent value Cp of the liquid level sensor when the liquid container is empty, and when the liquid container is filled with liquid, the detection chip obtains The capacitance equivalent value Cxi of each detection terminal, the sum of the capacitance equivalent values of all detection terminals is Cx=ΣCxi, all detection terminals overlapping with the liquid in the height direction will generate inductive capacitance, record the inductance of all detection terminals Inductive capacitance, among all detection terminals that generate inductive capacitance, calculate the inductive capacitance of all detection terminals below the detection terminal at the highest position with the rated value, and calculate the inductive capacitance of the detection terminal at the highest position with the real-time value.

One of the objectives to be achieved by the present invention is to provide a washing machine capable of accurately detecting the liquid level of the outer tub.

The present invention also provides a washing machine, which includes a machine body, an outer tub and an inner tub arranged in the body, and the outer wall of the outer tub is provided with the above-mentioned liquid level detection device.

As a preferred solution, the washing machine uses the above liquid level detection method to detect the liquid level of the outer tub.

As a further preferred solution, the washing machine further includes an MCU, and the detection chip converts the obtained capacitance equivalent value into a digital signal and sends it to the MCU.

One of the objectives of the present invention is to provide a washing machine capable of accurately detecting the liquid level of the detergent storage box.

The present invention also provides a washing machine, which includes a body and a detergent storage box disposed on the body, wherein the outer wall of the detergent storage box is provided with the above-mentioned liquid level detection device.

As a preferred solution, the washing machine uses the above liquid level detection method to detect the liquid level of the detergent storage box.

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing:

FIG. 1 is a schematic diagram of the distribution of detection terminals in Embodiment 1 of the present invention.

Detailed ways

Embodiment one:

The invention provides a liquid level detection device, which includes a liquid level sensor and a detection chip. The liquid level sensor sends signals to the detection chip. The liquid level sensor is a capacitive diaphragm sensor. On the outer wall of the liquid container, a plurality of detection terminals are arranged along the height direction of the liquid container, and the detection areas of two adjacent detection terminals in the height direction are overlapped, and each detection terminal is connected to the I/O pin of the detection chip. One-to-one connections.

First of all, this embodiment uses the induced capacitance to detect the liquid level. The detection terminal is set on the outer wall of the liquid container and is isolated from the liquid. It has a simple structure, high water resistance, and is also easy to install and set. In a relatively sealed space; secondly, using multiple detection terminals for segmental detection, the detection areas of two adjacent detection terminals in the height direction are overlapped, that is, the liquid level detected by each detection terminal is different. Compared with an overall continuous detection terminal, the base of the detection range of each detection terminal is reduced. Under the same process conditions, the deviation ratio of the detection results is the same. Since the base of the detection range of each detection terminal is reduced, the deviation of the detection results The value decreases, thereby improving the accuracy of the detection and calculation of the entire liquid level sensor; third, in the detection process, the detection chip first obtains the capacitance equivalent value Cp of the liquid level sensor when the liquid container is empty, and when the liquid container is filled with liquid, The detection chip obtains the capacitance equivalent value Cxi of each detection terminal. All detection terminals that overlap with the liquid in the height direction will generate induced capacitance. Record the induced capacitance of all detection terminals. Among the terminals, the inductive capacitance of all detection terminals below the detection terminal at the highest position is calculated with the rated value, and the inductive capacitance of the detection terminal at the highest position is calculated with the real-time value. Since there is no deviation in the rated value, the actual deviation value is only produced by one detection terminal, which has been significantly reduced, greatly improving the detection accuracy. There are two ways to calculate the rated value. The first one is to calculate the rated value with the full value of the detection terminal at the lowest position, and the other detection terminals get the rated value after subtracting the overlapping part from the full value. The second is to calculate the rated value at the highest position The rated value of the detection terminal is calculated from the full value, and the rated value is obtained by subtracting the overlapping part from the full value of other detection terminals.

As shown in Figure 1, for example, 10 detection terminals 2 are set on the outer wall of the liquid container 1, the detection range base S of all detection terminals is 2.1 cm, and the full value is the induced capacitance generated by the detection range base S, two adjacent The height ΔH of the overlapping portion of the two detection terminals is 0.1cm, and the detection deviation of each detection terminal is ±5%. Assuming that the actual liquid level H1 of the liquid container is 3.5cm, the second method is used for calculation, then there are only two Each detection terminal produces inductive capacitance, and the detection result is the rated value of one detection terminal plus the real-time value of one detection terminal=(2.1cm-0.1cm)+1.5cm±5%, the deviation is small, and if one The overall continuous detection terminal, its detection result is exactly 3.5cm ± 5%, and the deviation is obviously larger; Another example is that the actual liquid level H2 of the liquid container is 11cm, and the detection result of this embodiment is the rated value of 5 detection terminals plus The real-time value of the last detection terminal = (2.1cm-0.1cm)+(2.1cm-0.1cm)+(2.1cm-0.1cm)+(2.1cm-0.1cm)+(2.1cm-0.1cm)+1cm ±5%, the deviation is very small, and if a whole continuous detection terminal is used, the detection result is 11cm±5%, the deviation is very large. It can be seen that this embodiment improves the accuracy of the liquid level detection structure significantly, especially when the liquid level is high, the detection result is closer to the actual value, and the detection accuracy is higher. In another case, when the actual liquid level H3 of the liquid container is 6.05cm, which is located in the overlapping area of two adjacent detection terminals, the detection result at this time is the rated value of the three detection terminals plus the real-time value of one detection terminal = (2.1cm-0.1cm)+(2.1cm-0.1cm)+(2.1cm-0.1cm)+0.05cm±5%, the deviation between the test result and the actual result is even smaller. Of course, it is also feasible to use the first method to calculate the rated value.

Each detection terminal is connected one-to-one with the I/O pins of the detection chip, which can be connected one by one, or the lead wire of each detection terminal can be connected to the public terminal first, and then the I/O pins of the detection chip can be connected by wires. The O pin is connected to the female terminal, and one-to-one connection is realized after plugging the male terminal and the female terminal, which is convenient for assembly and improves assembly efficiency. The connection here refers to electrical conduction after connection.

The detection terminal is generally formed by coating a conductive medium on a non-conductive material, such as coating silver paste on a PCB or glass, etc. The liquid level sensor can be pasted or formed on the outer wall of the liquid container, and will not be affected by the aging of the liquid container, the wall Influenced by factors such as uneven thickness, the precision is high and the detection result is reliable.

The shape of the detection terminal is not limited to the V shape shown in FIG. 1 , and geometric shapes such as linear, rectangular, circular, etc. may also be used.

Embodiment two:

A liquid level detection method, using the liquid level detection device described in Embodiment 1, the detection chip first obtains the capacitance equivalent value Cp of the liquid level sensor when the liquid container is empty, and when the liquid container is filled with liquid, the detection chip Obtain the capacitance equivalent value Cxi of each detection terminal, the sum of the capacitance equivalent values of all detection terminals is Cx=ΣCxi, all detection terminals overlapping with the liquid in the height direction will generate induced capacitance, record the capacitance of all detection terminals The sum of the induced capacitance Cs, and then subtract the sum of the induced capacitance value Ct of all detection terminals that generate the induced capacitance that overlaps with the previous detection terminal, according to the formula Cx=Cp+Cs-Ct, Cs=εo×εr×A /D, calculate A, and then calculate the liquid level height of the liquid according to the area formula, where:

εo = permittivity of free space;

εr = insulation constant of liquid level sensor;

A = the overlapping area of the liquid and the detection terminal;

D = Thickness of detection terminal.

The last detection terminal refers to the detection terminal that is lower in the height direction among the two overlapping detection terminals. Since the inductive capacitance of the overlapping part of the two detection terminals will be recorded, it is equivalent to calculating twice, so it needs to be subtracted once .

A conversion circuit is provided between the detection chip and the liquid level sensor. The conversion circuit converts the capacitance equivalent value Cxi of each detection terminal into a digital key value, and the detection chip stores the digital key value. The detection chip can temporarily store the corresponding liquid level data to avoid loss after a sudden power failure. After the power is restored, there is no need to re-test, and the test results can be obtained directly. The detection chip can also permanently store the liquid level data, collect feedback on the user's usage habits, and in turn optimize the program to improve the user's experience.

Embodiment three:

A liquid level detection method, using the liquid level detection device described in Embodiment 1, the detection chip first obtains the capacitance equivalent value Cp of the liquid level sensor when the liquid container is empty, and when the liquid container is filled with liquid, the detection chip Obtain the capacitance equivalent value Cxi of each detection terminal, the sum of the capacitance equivalent values of all detection terminals is Cx=ΣCxi, all detection terminals overlapping with the liquid in the height direction will generate induced capacitance, record the capacitance of all detection terminals Inductive capacitance, among all detection terminals that generate inductive capacitance, calculate the inductive capacitance of all detection terminals below the detection terminal at the highest position with the rated value, and calculate the inductive capacitance of the detection terminal at the highest position with the real-time value.

For the effect of this embodiment, reference may be made to Embodiment 1. For other content not described, please refer to Embodiment 2.

Embodiment four:

A washing machine includes a machine body, an outer tub and an inner tub arranged in the body, and the outer wall of the outer tub is provided with the liquid level detection device described in the first embodiment.

The washing machine in this embodiment can use the liquid level detection method in Embodiment 2 or Embodiment 3 to detect the liquid level of the outer tub.

This embodiment can be used to detect in real time the water intake, discharge, etc. of the washing machine during the washing process. The liquid level detection result is accurate, which can precisely control the washing time and washing water consumption, and promote the improvement of washing effect.

In order to apply the liquid level detection result to the washing program of the washing machine, the washing machine may further include an MCU, and the detection chip converts the obtained capacitance equivalent value into a digital signal and sends it to the MCU. The MCU can judge the water intake or discharge volume according to the liquid level detection result, so as to control the washing machine to work.

Embodiment five:

A washing machine includes a body and a detergent storage box arranged on the body. The outer wall of the detergent storage box is provided with the liquid level detection device described in the first embodiment. The detergent storage box is used to store liquid detergents, such as laundry detergent, softener, etc.

The washing machine of this embodiment can use the liquid level detection method of Embodiment 2 or Embodiment 3 to detect the liquid level of the detergent storage box, which can be used to control the amount of detergent automatically injected to achieve precise and intelligent washing. Remind users to add detergent in time after use.

Referring to Embodiment 4, the washing machine of this embodiment may also include an MCU, and the detection chip converts the obtained capacitance equivalent value into a digital signal and sends it to the MCU.

The washing machine in the present invention can be common types of washing machines such as wave-wheel washing machines and roller washing machines. Except above-mentioned preferred embodiment, the present invention also has other implementation modes, those skilled in the art can make various changes and distortions according to the present invention, as long as not departing from the spirit of the present invention, all should belong to the defined in the claims of the present invention scope.

Claims (10)

1. a kind of liquid level detection device, including liquid level sensor and detection chip, liquid level sensor sends signal to detection chip, It is characterized in that, the liquid level sensor is condenser type membrane sensor, liquid level sensor is equipped with multiple detection terminals, test side Son is located at the lateral wall of liquid container, and multiple detection terminals are arranged along the short transverse of liquid container, adjacent in the height direction The detection zones of two detection terminals overlap, the one-to-one connection of I/O pin of each detection terminal and detection chip.

2. liquid level detection device according to claim 1, which is characterized in that liquid is pasted or be molded over to the liquid level sensor The lateral wall of body container.

3. a kind of liquid-level detecting method, using liquid level detection device of any of claims 1 or 2, which is characterized in that detection chip Capacitor equivalent value Cp of the liquid level sensor when liquid container is vacant is first obtained, after filling liquid in liquid container, detects core Piece obtains the capacitor equivalent value Cxi of each detection terminal, and the capacitor equivalent value summation of all detection terminals is Cx=Σ Cxi, with Liquid has overlapping all detection terminals that can generate capacitor of inducting in the height direction, records the capacitor of inducting of all detection terminals Summation Cs, then the capacitance summation Ct that inducts of each detection terminal Yu upper detection terminal lap is subtracted, according to formula Cx =Cp+Cs-Ct, Cs=ε o × ε r × A/D calculate A, and then formula calculates the liquid level for obtaining liquid according to area, in which:

ε o=free space dielectric constant；

The dielectric constant of ε r=liquid level sensor；

The overlapping area of A=liquid and detection terminal；

The thickness of D=detection terminal.

4. liquid-level detecting method according to claim 3, which is characterized in that between the detection chip and liquid level sensor Equipped with conversion circuit, the capacitor equivalent value Cxi of each detection terminal is converted into digital key assignments, detection chip storage by conversion circuit Digital key assignments.

5. a kind of liquid-level detecting method, using liquid level detection device of any of claims 1 or 2, which is characterized in that detection chip Capacitor equivalent value Cp of the liquid level sensor when liquid container is vacant is first obtained, after filling liquid in liquid container, detects core Piece obtains the capacitor equivalent value Cxi of each detection terminal, and the capacitor equivalent value summation of all detection terminals is Cx=Σ Cxi, with Liquid has overlapping all detection terminals that can generate capacitor of inducting in the height direction, records the electricity of inducting of all detection terminals Hold, in all detection terminals for generating and inducting capacitor, the detection terminal institute below for being located at extreme higher position is calculated with rated value There is the capacitor of inducting of detection terminal, the capacitor of inducting for being located at the detection terminal of extreme higher position is calculated with real value.

6. a kind of washing machine, including body and it is set to the intracorporal outer barrel of machine, interior bucket, which is characterized in that the lateral wall of said tub Equipped with liquid level detection device of any of claims 1 or 2.

7. washing machine according to claim 6, which is characterized in that the washing machine is using described in claim 3 or 4 or 5 Liquid-level detecting method detect the liquid level of outer barrel.

8. washing machine according to claim 7, which is characterized in that the washing machine further includes MCU, and detection chip will acquire Capacitor equivalent value be converted into digital signal and be sent to MCU.

9. a kind of washing machine, including body and set on the detergent the storage box of body, which is characterized in that the detergent the storage box Lateral wall be equipped with liquid level detection device of any of claims 1 or 2.

10. washing machine according to claim 9, which is characterized in that the washing machine is using described in claim 3 or 4 or 5 Liquid-level detecting method detect the liquid level of detergent the storage box.