Thermal resistance type dry-wet detection sensor, electric appliance and detection method

Abstract

The invention relates to the technical field of sensors, in particular to a thermal resistance type dry-wet detection sensor, an electric appliance and a detection method, and the thermal resistance type dry-wet detection sensor comprises a switch module, a detection module and a conversion module which are connected in sequence; the switch module is used for controlling the power-on or power-off state of the detection module and the conversion module; the detection module is used for detecting the surface dryness and wetness of a detected object; the conversion module is used for sampling heat loss data of the detection module and converting the heat loss data into temperature in real time for outputting; a thermal resistance principle is adopted, when a dry or humid surface of a measured object is in direct contact with a heat conduction substrate, heat change data of the heat conduction substrate is collected through an NTC resistor and converted into self resistance change, and then the current humidity data of the measured object is quantized and output through an analog-to-digital converter; the interference of factors such as water drop hanging on the wall and material conductivity on the thermal resistance type dry-wet detection sensor is avoided, and the thermal resistance type dry-wet detection sensor is fast in detection response, accurate in detection and low in cost.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, specifically to a thermal resistance type dry and wet detection sensor, an electrical appliance, and a detection method. Background Technology

[0002] Currently, floor scrubbers are household appliances used for washing and mopping floors. Existing floor scrubbers use various types of wet and dry sensors to detect the dryness and moisture content of the floor, including resistive sensors, capacitive sensors, infrared multispectral sensors, and ultrasonic sensors. However, in actual use, these types of wet and dry sensors suffer from problems such as water droplets adhering to the wall and low material conductivity, which not only reduce the detection speed and accuracy of the sensors and shorten their lifespan but also increase maintenance costs.

[0003] Therefore, the applicant hereby proposes a thermal resistance dry / wet detection sensor, an electrical appliance, and a detection method to solve the aforementioned problems. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a thermal resistance dry / wet detection sensor, an electrical appliance, and a detection method.

[0005] The technical solution of this invention is as follows:

[0006] This invention provides a thermal resistance type dryness and wetness detection sensor, comprising a switching module, a detection module and a conversion module connected in sequence;

[0007] The switching module is used to control the power-on or power-off state of the detection module and the conversion module;

[0008] The detection module is used to detect the degree of dryness or wetness on the surface of the tested item;

[0009] The conversion module is used to sample the heat loss data of the detection module and convert it into temperature in real time for output.

[0010] Furthermore, the switching module includes a PWM signal source, a first resistor R5, an NPN transistor Q2, and a PMOS transistor Q3; the output terminal of the PWM signal source is connected to one end of the first resistor R5, the other end of the first resistor R5 is connected to the base of the NPN transistor Q2, the collector of the NPN transistor Q2 is connected to the gate of the PMOS transistor, the emitter of the NPN transistor Q2 is grounded, the source and drain of the PMOS transistor Q3 are connected to the power supply bus and the input terminal of the detection module, respectively, and a pull-down resistor R4 is connected between the gate and source of the PMOS transistor Q3.

[0011] Furthermore, the detection module includes a thermally conductive substrate, a power resistor R2, and an NTC resistor; the power resistor R2 and the NTC resistor are respectively disposed on both ends of the thermally conductive substrate, the input terminals of the power resistor R2 and the NTC resistor are respectively connected to the drain of the POMS tube and the input terminal of the conversion module, and the output terminals of the power resistor R2 and the NTC resistor are respectively grounded.

[0012] Furthermore, the conversion module includes an analog-to-digital converter and a first-order low-pass filter; the first-order low-pass filter is connected between the receiving end of the analog-to-digital converter and the output end of the NRC resistor.

[0013] Furthermore, the thermally conductive substrate is made of a material with thermal conductivity.

[0014] Furthermore, the thermally conductive substrate is an aluminum substrate.

[0015] The present invention also provides a thermal resistance-based method for detecting dryness and wetness, S1: the switching module is turned on, current flows through the power resistor R2 to make it heat up, and the temperature of the thermally conductive substrate rises;

[0016] S2: The dry or wet surface of the test object is brought into direct contact with the thermally conductive substrate, and the NTC resistor collects the heat loss data of the thermally conductive substrate.

[0017] S3: The heat loss data sampled by NTC is filtered by a first-order low-pass filter and then controlled by PID at a temperature 5 degrees higher than room temperature.

[0018] S4: The output of the PID controller is passed through a first-order low-pass filter to form an approximate output power;

[0019] S5: Determine whether the surface of the object being tested is dry or wet by approximate output power;

[0020] S6: Use a hygrometer to pre-acquire each humidity data point;

[0021] S7: The linear relationship between output power, temperature data and humidity is calibrated using the least squares method;

[0022] S8: Get the current humidity data.

[0023] The present invention also provides an electrical appliance with a thermal resistance wet / dry detection sensor, including the aforementioned thermal resistance wet / dry detection sensor.

[0024] The beneficial effects achieved by this invention are as follows:

[0025] The present invention provides a thermal resistance type dry and wet detection sensor, electrical appliance, and detection method. It adopts the thermal resistance principle. When the surface of the dry or wet object is in direct contact with the thermally conductive substrate, the heat change data of the thermally conductive substrate is collected by the NTC resistor and converted into the change of its own resistance. Then, the analog-to-digital converter quantizes and outputs the current humidity data of the object. It avoids the interference of factors such as water droplets on the wall and the conductivity of the material on the thermal resistance type dry and wet detection sensor. It has fast detection response, accurate detection, and low cost. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0027] Figure 2 This is the circuit diagram of the present invention.

[0028] Figure 3 This is a flowchart illustrating the present invention.

[0029] Figure 4 This is a schematic diagram of the method steps of the present invention. Detailed Implementation

[0030] To facilitate understanding of the present invention by those skilled in the art, specific embodiments of the present invention are clearly described below with reference to the accompanying drawings. Obviously, the specific embodiments described are merely preferred embodiments of the present invention, and not all embodiments.

[0031] like Figure 1-4 As shown, the present invention provides a thermal resistance wet / dry detection sensor, which is used in floor scrubbers to detect and distinguish the wetness of the floor; it includes a switch module, a detection module and a conversion module connected in sequence.

[0032] The switching module is used to control the power-on or power-off state of the detection module and the conversion module;

[0033] The detection module is used to detect the degree of dryness or wetness on the surface of the tested item;

[0034] The conversion module is used to sample the heat loss data of the detection module and convert it into temperature in real time for output.

[0035] The switching module includes a PWM signal source for providing high and low level signals, a first resistor R5 for current limiting protection, an NPN transistor Q2 for converting the PWM signal into a current sufficient to drive the gate of a PMOS transistor Q3, and a PMOS transistor Q3 for precisely controlling the connection state between the detection module and the power supply. The output terminal of the PWM signal source is connected to one end of the first resistor R5, the other end of the first resistor R5 is connected to the base of the NPN transistor Q2, the collector of the NPN transistor Q2 is connected to the gate of the PMOS transistor Q3, the emitter of the NPN transistor Q2 is grounded, the source and drain of the PMOS transistor Q3 are connected to the power supply bus and the input terminal of the detection module, respectively, and a pull-down resistor R4 is connected between the gate and source of the PMOS transistor Q3.

[0036] The detection module includes a thermally conductive substrate for guiding heat distribution, a power resistor R2 for converting electrical energy into heat, and an NTC resistor for converting heat into resistance. The power resistor R2 and the NTC resistor are respectively disposed at both ends of the thermally conductive substrate. The input terminals of the power resistor R2 and the NTC resistor are respectively connected to the drain of the POMS tube and the input terminal of the conversion module, and the output terminals of the power resistor R2 and the NTC resistor are respectively grounded. The thermally conductive substrate is made of a material with thermal conductivity, and in this example, an aluminum substrate is preferred.

[0037] The conversion module includes an analog-to-digital converter for converting signals and a first-order low-pass filter for filtering out noise; the first-order low-pass filter is connected between the receiving end of the analog-to-digital converter and the output end of the NRC resistor.

[0038] Working principle: A high-level or low-level signal is input from a PWM signal source. Current flows through the first resistor R5 and the transistor, turning it on or off. At the same time, the gate of PMOS transistor Q3 is pulled low or high, controlling the conduction or turn-off of PMOS transistor Q3. When PMOS transistor Q3 is on, current flows through the power resistor R2, putting it into working state and generating heat. The heat is distributed on the heat-conducting substrate, sampled by an NTC resistor, and converted into temperature display by an analog-to-digital converter. Conversely, when PMOS transistor Q3 is off, current does not flow through the power resistor R2, causing it to exit working state and stop generating heat.

[0039] The present invention also provides a thermal resistance-based method for detecting dryness and wetness, comprising the following steps:

[0040] S1: The switching module is turned on, and the current flows through the power resistor R2, causing it to heat up, which in turn raises the temperature of the heat-conducting substrate.

[0041] S2: The dry or wet surface of the test object is brought into direct contact with the thermally conductive substrate, and the NTC resistor collects the heat loss data of the thermally conductive substrate. When the roller or towel is in direct contact with the thermally conductive substrate, there will be a power variation. When the contact surface is dry, the thermal resistance is high, and only a low power is needed to maintain the temperature. At this time, the output power variation is within 10%, and there will be some variation due to friction. When the contact surface is wet, the thermal resistance is low, and the heat loss is serious. The output power variation is within 10% to 100%. At this time, the data window can be used as a key observation carrier. By observing the differences in the phenomena presented, the presence of water on the contact surface can be effectively identified. The output power and the actual dryness and humidity of the contact surface can be approximately linearly related.

[0042] S3: The heat loss data sampled by NTC is filtered by a first-order low-pass filter and then controlled by PID at a temperature 5 degrees higher than room temperature.

[0043] S4: The output of the PID controller is passed through a first-order low-pass filter to form an approximate output power;

[0044] S5: The surface of the object being tested is determined to be dry or wet by approximate output power. In this embodiment, the maximum output power is 8W. Under normal control, the output power is less than 0.8W when there is no water and greater than 0.8W when there is water. The discrimination window algorithm can identify whether there is water on the surface of the object being tested.

[0045] S6: Use a hygrometer to pre-acquire each humidity data point;

[0046] S7: The linear relationship between output power, temperature data and humidity is calibrated using the least squares method;

[0047] S8: Get the current humidity data.

[0048] The present invention also provides an electrical appliance with a thermal resistance wet / dry detection sensor, including the thermal resistance wet / dry detection sensor described in the above embodiments. The electrical appliance can be a household appliance such as a robot vacuum cleaner or a floor scrubber.

[0049] The embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A thermal resistance type wet / dry detection sensor, characterized in that: It includes a switch module, a detection module, and a conversion module connected in sequence; The switching module is used to control the power-on or power-off state of the detection module and the conversion module; The detection module is used to detect the degree of dryness or wetness on the surface of the tested item; The conversion module is used to sample the heat loss data of the detection module and convert it into temperature in real time for output.

2. The thermal resistance type wet / dry detection sensor according to claim 1, characterized in that: The switching module includes a PWM signal source, a first resistor R5, an NPN transistor Q2, and a PMOS transistor Q3. The output terminal of the PWM signal source is connected to one end of the first resistor R5, and the other end of the first resistor R5 is connected to the base of the NPN transistor Q2. The collector of the NPN transistor Q2 is connected to the gate of the PMOS transistor Q3, and the emitter of the NPN transistor Q2 is grounded. The source and drain of the PMOS transistor Q3 are connected to the power supply bus and the input terminal of the detection module, respectively. A pull-down resistor R4 is connected between the gate and source of the PMOS transistor Q3.

3. The thermal resistance type wet / dry detection sensor according to claim 2, characterized in that: The detection module includes a thermally conductive substrate, a power resistor R2, and an NTC resistor. The power resistor R2 and the NTC resistor are respectively disposed on both ends of the thermally conductive substrate. The input terminals of the power resistor R2 and the NTC resistor are respectively connected to the drain of the POMS tube and the input terminal of the conversion module. The output terminals of the power resistor R2 and the NTC resistor are respectively grounded.

4. A thermal resistance type wet / dry detection sensor according to any one of claims 1-3, characterized in that: The conversion module includes an analog-to-digital converter and a first-order low-pass filter; the first-order low-pass filter is connected between the receiving end of the analog-to-digital converter and the output end of the NTC resistor.

5. A thermal resistance type wet / dry detection sensor according to claim 3, characterized in that: The thermally conductive substrate is made of a material with thermal conductivity.

6. A thermal resistance type wet / dry detection sensor according to claim 5, characterized in that: The thermally conductive substrate is an aluminum substrate.

7. A thermal resistance-based method for detecting dryness and wetness, characterized in that: S1: The switching module is turned on, and the current flows through the power resistor R2, causing it to heat up, which in turn raises the temperature of the heat-conducting substrate. S2: The dry or wet surface of the test object is brought into direct contact with the thermally conductive substrate, and the NTC resistor collects the heat loss data of the thermally conductive substrate. S3: The heat loss data sampled by NTC is filtered by a first-order low-pass filter and then controlled by PID at a temperature 5 degrees higher than room temperature. S4: The output of the PID controller is passed through a first-order low-pass filter to form an approximate output power; S5: Determine whether the surface of the object being tested is dry or wet by approximate output power; S6: Use a hygrometer to pre-acquire each humidity data point; S7: The linear relationship between output power, temperature data and humidity is calibrated using the least squares method; S8: Get the current humidity data.

8. An electrical appliance with a thermal resistance type wet / dry detection sensor, characterized in that: The present invention includes a thermal resistance wet / dry detection sensor as described in any one of claims 1-6.

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