CN211484447U - Liquid level detection device and dish washing machine - Google Patents

Abstract

The utility model provides a pair of liquid level detection device and dish washer, liquid level detection device includes: the first circuit comprises a first metal probe positioned at a first set height of the liquid container, and the first metal probe is connected to a first power supply end through a first resistor and is connected to a first output end through a second resistor; the energy storage circuit comprises a third metal probe positioned at the lowest position of the liquid container, and the third metal probe is grounded through an energy storage capacitor; the control chip is provided with a driving end and a first acquisition end, wherein the driving end is used for outputting pulse voltage to the first power end, and the first acquisition end is used for acquiring probe signals through the first output end; and judging whether liquid exists at the first set height through the probe signal. So design, it is less influenced by liquid nature to keep apart earth disturbing signal, can effectively avoid the environment to the interference of liquid level detection, promoted the degree of accuracy of liquid level detection. Compared with the prior art of Hall detection or proximity switch detection, the circuit is simple, easy to realize and low in cost.

Description

Liquid level detection device and dish washing machine

Technical Field

The utility model relates to a liquid level detection device technical field, concretely relates to liquid level detection circuit and dish washer.

Background

At present, household appliances such as dish washers, hot water kettles, electric water heating tanks, washing machines and the like which comprise liquid containers are necessities of people's home life, and along with the progress of technology, the household appliances are developed in a more intelligent direction. The automatic control of liquid containers is an important direction for the development of intellectualization. The detection of the liquid level in the liquid container is a key index for automatic control and is also a basis for ensuring the safe operation of the household appliances. Therefore, the accurate measurement of the liquid level in the liquid container is a necessary premise for realizing intellectualization.

In view of this, the patent publication No. CN107192424A discloses a method for detecting water amount in an electric kettle based on conductivity, which is provided with a kettle body equipped with a water level probe for detecting water amount information, the water level probe is electrically connected to a control panel inside the kettle body, and the control panel judges the corresponding water amount information according to conductivity values detected by the water level probes at different water level points.

Although the above patent can realize the detection of the liquid level, the conductivity is greatly influenced by the liquid properties, components, temperature and other factors, the accuracy of the detection result is not high, and a great measurement error is easily caused. In addition, in the test process, the current value obtained by direct detection is too small, and the current value is greatly interfered by the outside, so that the design of the detection circuit is difficult.

SUMMERY OF THE UTILITY MODEL

Therefore, the to-be-solved technical problem of the utility model lies in overcoming the liquid level detection device among the prior art and detecting the structure inaccurate, receives the interference easily, and the circuit design degree of difficulty is big grade defect to a liquid level detection device and dish washer are provided.

The utility model provides a pair of liquid level detection device, include:

the first circuit comprises a first metal probe positioned at a first set height of the liquid container, and the first metal probe is connected to a first power supply end through a first resistor and is connected to a first output end through a second resistor;

the energy storage circuit comprises a third metal probe positioned at the lowest position of the liquid container, and the third metal probe is grounded through an energy storage capacitor;

the control chip is provided with a driving end for outputting pulse voltage to the first power supply end and a first acquisition end for acquiring a probe signal through the first output end; and judging whether liquid exists at the first set height or not through the probe signal.

Optionally, the liquid container further comprises a second circuit, the second circuit comprises a second metal probe located at a second set height of the liquid container, and the second metal probe is connected to a second power end through a third resistor and is connected to the first output end through a fourth resistor; the second power end is electrically connected with the driving end, and the control chip is further provided with a second acquisition end for acquiring probe signals through the second output end.

Optionally, the first resistor and the third resistor have the same resistance, and the second resistor and the fourth resistor have the same resistance.

The utility model also provides a dish washer, above-mentioned arbitrary liquid level detection device.

The utility model discloses technical scheme has following advantage:

the utility model provides a pair of liquid level detection device, so design, it is less influenced by liquid nature to keep apart the earth interference signal, can effectively avoid the environment to the interference of liquid level detection, promoted the degree of accuracy of liquid level detection. Compared with the prior art of Hall detection or proximity switch detection, the circuit is simple, easy to realize and low in cost.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the technical solutions in the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic structural view of a liquid container according to a first embodiment of the present invention;

fig. 2 is a schematic diagram of a first circuit provided in a first embodiment of the present invention;

fig. 3 is a schematic diagram of a second circuit provided in the first embodiment of the present invention;

fig. 4 is a schematic diagram of a tank circuit provided in a first embodiment of the present invention;

fig. 5 is a first detection waveform diagram provided in the first embodiment of the present invention;

fig. 6 is a diagram of a second detection waveform provided in the first embodiment of the present invention;

fig. 7 is a third detection waveform diagram provided in the first embodiment of the present invention.

Description of reference numerals:

10-liquid inlet, 11-liquid container, 12-dish washing liquid or rinsing agent and 13-liquid outlet.

Detailed Description

The technical solution of the present invention will be described clearly and completely with reference to the accompanying drawings, and obviously, the described embodiments are some, but not all embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

The embodiment of the utility model provides a dish washer. The dishwasher comprises aliquid container 11 for receiving dishwashing liquid orrinsing agent 12 required for washing. As shown in fig. 1, theliquid container 11 includes aliquid inlet 10 at the top and aliquid outlet 13 at the bottom. In order to facilitate a more intelligent and accurate detection of the usage of the dishwashing liquid or therinsing agent 12 in theliquid container 11, the dishwasher is further provided with a liquid level detection device.

The liquid level detection device comprises a first metal probe 1, a second metal probe 2 and a third metal probe 3 which are arranged on the inner wall of aliquid container 11. The first metal probe 1 is located at a first set height near the height of theliquid inlet 10 for detecting a high liquid level. The second metal probe 2 is arranged at a second set height close to the height of theliquid outlet 13 and used for detecting a low liquid level. And the third metal probe 3 is disposed at the lowest position of theliquid container 11 as a common probe.

As shown in fig. 2 to 3, the first metal probe 1 is connected to the first power source terminal through a first resistor R1, and is connected to the first output terminal Level _ H through a second resistor R2. The second metal probe 2 is connected to the second power supply terminal through a third resistor R3, and is connected to the second output terminal Level _ L through a fourth resistor R4. The first resistor R1 and the third resistor R3 are pull-up resistors and have the same resistance. The second resistor R2 and the fourth resistor R4 are current-limiting resistors and have the same resistance. The first output end Level _ H and the second output end Level _ L are respectively and electrically connected with the first acquisition end and the second acquisition end of the control chip. The first power supply end and the second power supply end are connected with the driving end of the control chip at the same time and receive the PWM driving signal output by the driving end. The first metal probe 1, the first resistor R1 and the second resistor R2 form a first circuit, and the second metal probe 2, the third resistor R3 and the fourth resistor R4 form a second circuit.

The liquid level detecting device further includes an energy storage circuit formed by a capacitor C1, referring to fig. 4, the capacitor C1 is an energy storage capacitor, one end of C1 is connected to the third metal probe 3, and the other end is grounded. When the first metal probe 1 and the second metal probe 2 are respectively communicated with the third metal probe 3 through dishwashing liquid orrinsing agent 12 in theliquid container 11, two charging and discharging loops are respectively formed.

When the liquid level detection device needs to work, the control chip outputs PWM driving waveforms with fixed duty ratio and VCC amplitude to the first power supply end and the second power supply end through the driving end.

The working principle of the liquid level detection circuit is as follows:

when a user uses the dishwasher to start up, the liquid level detection device starts to work, three metal probe signals are collected, and the collected probe signals are fed back to the main controller. The liquid level of the dishwashing liquid or therinsing agent 12 in theliquid container 11 can be determined by detecting, calculating and analyzing the relationship between the VCC and the maximum value of the probe signal. Specifically, the method comprises the following steps:

when the dishwashing liquid orrinsing agent 12 in the liquid container is higher than a first set height, the dishwashing liquid orrinsing agent 12 enables the first metal probe 1, the second metal probe 2 and the third metal probe 3 to form a current loop. The waveform of the probe signal collected by the first collecting terminal through the first output terminal is shown in fig. 5, the maximum value is aVCC, and the waveform of the probe signal collected by the second collecting terminal through the second output terminal is the same as that in fig. 5 because the first circuit and the second circuit are in parallel connection, and the resistance is equal.

Therefore, by analyzing whether aVCC is less than VCC, in this embodiment, more precisely less than 0.5 times VCC, it can be determined that the dishwashing liquid or the rinsing agent in the liquid container is higher than the first set height. The relationship between the threshold and VCC is determined by the resistance in the actual circuit and the capacitance between the C1 capacitive reactance, the metal probe and the water.

If the dishwashing liquid or therinsing agent 12 in theliquid container 11 is higher than the first set height, which indicates that the corresponding dishwashing liquid or therinsing agent 12 in theliquid container 11 is full, the process continues to the next process, and the liquid level detection device is not operated until the current washing process is finished.

When the dishwashing liquid or rinseagent 12 in theliquid container 11 is below a second set level, the first and second circuits fail to form a current circuit. A first detection waveform acquired by the first acquisition end through the first output end and a second detection waveform acquired by the second acquisition end through the second output end are shown in fig. 7, and the detection waveforms are square waves with the same duty ratio as the PWM driving waveform.

The maximum values of the first detection waveform and the second detection waveform are aVCC and bVCC respectively; therefore, whether aVCC, bVCC and VCC are equal or not is judged, and when the aVCC, the bVCC and VCC are equal, the liquid level can be judged to be lower than the second set height. And when the dishwashing liquid or the rinsingagent 12 in theliquid container 11 is lower than the second set height, it indicates that the dishwashing liquid or the rinsingagent 12 is not available in theliquid container 11, and the user needs to be reminded to add the dishwashing liquid or the rinsing agent by a corresponding reminding mode. The reminding mode can be buzzing alarm reminding, indicator light flicker reminding or buzzing and indicator light simultaneous reminding.

When the dishwashing liquid or rinseagent 12 in theliquid container 11 is between the first set level and the second set level, the dishwashing liquid or rinseagent 12 merely completes the second circuit with the stored energy current in a current circuit. The first detection waveform acquired by the first acquisition end through the first output end is a square wave with the same duty ratio as the PWM driving waveform. The maximum value of the first detection waveform is acvcc, the second detection waveform acquired by the second acquisition end through the second output end is shown in fig. 6, and the maximum value is bVCC.

Therefore, whether aVCC is equal to VCC and bVCC is less than VCC is judged, and if yes, the liquid level is judged to be between the first set height and the second set height. When the liquid level is between the first set height and the second set height, dish washing liquid or rinsing agent is still contained in the liquid container for the user to use, the main program continues to be carried out to the next program, and before the main program sends a next throwing instruction, the probe circuit works again to judge whether the residual dish washing liquid or rinsing agent is used up.

It can be known through the above description that the liquid level detection device in this embodiment is so designed, receives liquid nature influence less to keep apart earth disturbing signal, can effectively avoid the environment to liquid level detection's interference, promoted liquid level detection's the degree of accuracy. Compared with the prior art of Hall detection or proximity switch detection, the circuit is simple, easy to realize and low in cost.

As an alternative embodiment, only one detection circuit may be provided, i.e. the first loop or the second loop is retained. A plurality of detection circuits can be arranged, so that the liquid level detection gradient is more, and the accuracy is better. In addition, the resistance value can be determined according to actual conditions, and is not limited to an equal design.

As an alternative, the level position can also be detected by detecting a difference. In particular, the amount of the solvent to be used,

when the resistance values of the first resistor and the third resistor are equal, and the resistance values of the second resistor and the fourth resistor are equal; through comparison VCC and aVCC and bVCC judge the liquid level position, include:

when 0 < | VCC-aVCC | < 0.5VCC, it is determined that the liquid level is not lower than the first set height.

Through comparison VCC and aVCC and bVCC judge the liquid level position, still include:

and when the absolute VCC-aVCC is less than the absolute VCC-bVCC and is less than VCC, the liquid level is judged to be lower than a second set height.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications can be made without departing from the scope of the invention.

Claims (5)

1. A liquid level detection device, comprising:

a first circuit comprising a first metal probe (1) at a first set height of the liquid container (11), said first metal probe (1) being connected to a first power supply terminal via a first resistor (R1) and to a first output terminal via a second resistor (R2);

a tank circuit comprising a third metal probe (3) located at the lowest position of the liquid container (11), the third metal probe (3) being connected to ground via a tank capacitor (C1);

the control chip is provided with a driving end for outputting pulse voltage to the first power supply end and a first acquisition end for acquiring a probe signal through the first output end; and judging whether liquid exists at the first set height or not through the probe signal.

2. The fluid level detection apparatus of claim 1, wherein: further comprising a second circuit comprising a second metal probe (2) at a second set level of said liquid container (11), said second metal probe (2) being connected to a second power supply terminal via a third resistor (R3) and to a first output terminal via a fourth resistor (R4); the second power end is electrically connected with the driving end, and the control chip is further provided with a second acquisition end for acquiring probe signals through a second output end.

3. The liquid level detection apparatus of claim 2, wherein: the first resistor (R1) and the third resistor (R3) are equal in resistance value, and the second resistor (R2) and the fourth resistor (R4) are equal in resistance value.

4. The liquid level detection apparatus of claim 2, wherein: the first set height is higher than the second set height.

5. A dishwasher, characterized by: comprising a liquid level detection device according to any of claims 1-4.

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