CN1955370A - Drying Judging Device and Drying Judging Method for Dryer - Google Patents

Abstract

A method for judging the dried level of baker includes such steps as detecting ambient temp Ts, detecting the temp Tc at the air outlet of baker, calculating the difference between Ts and Tc by Tc-Ts, comparing the difference with a predefined value To, and judging that the object has been dried if said difference is greater than To. Its judging device is composed of a temp sensor at the air outlet of baker, and a controller.

Description

Drying Judging Device and Drying Judging Method for Dryer

technical field

The invention relates to a dryer, in particular to a drying judging device for a dryer. The invention also provides a drying judging method.

Background technique

Dryers and washing machines with dryer functions are becoming more and more popular. Under the prior art, most dryers adopt the method of timing drying. This approach has many drawbacks. When the dried object is relatively dry, if you choose to dry for a long time, it will inevitably waste electric energy and even damage the dried object; if the dried object is wet, it may not meet the drying requirements, and you have to repeat the operation and delay the time. The above problems also cause the drying process to be taken care of by people, making it difficult to realize real automatic drying.

In the prior art, several methods have been proposed for the drying judgment of the dryer. Most existing technologies use humidity sensors to detect dryness. However, there are many defects in the humidity sensor, such as: high price, unstable work, obvious environmental impact, need to correct or compensate, short life, etc., and most of the current humidity sensors require pulse power supply, which will make the control circuit complication. The above problems have prevented this detection method from being widely used.

The application number is 99119576, and the Chinese invention patent titled "Method and Device for Automatic Shutdown of Clothes Dryer" discloses a method for automatic shutdown of clothes dryer through temperature detection. The method is based on temperature detection. By detecting the temperature inside the dryer and comparing the temperature with the set control temperature, when the temperature difference is greater than a set value, it will be heated with full power; , reduce the heating power; adjust the heating power to ensure that the difference between the measured temperature and the set temperature is less than the difference between the two measured temperature values. When it is less than the shutdown power several times in a row, it will stop. The invention also provides a device for using the method.

The method provided by this invention patent avoids the problem of using a humidity sensor because only the temperature sensor is used to realize the drying judgment of the clothes dryer. The principle of the invention is that during the drying process, as the humidity decreases, the dryness becomes higher and higher, and the temperature change caused by the dryness change also decreases accordingly, so it can be judged whether the clothes are dry by detecting the temperature.

The problem of this prior art is that the drying judgment of the object to be dried and the control process of the dryer proposed by it are too complicated, and the measures that can be taken to judge the degree of dryness more accurately are not considered. The temperature change during the drying process is related to the ambient temperature and the heating power, but this prior art does not take these factors into consideration.

Contents of the invention

In view of the above defects, the technical problem to be solved by the present invention is to provide a dryer drying judging device and a judging method. The device and method also use the temperature sensor to judge drying, but the drying judging method and the control flow of the dryer are simpler. At the same time, the measures to improve the judgment accuracy of dryness are put forward. The method and device provided by the invention can more simply and accurately judge whether the dried object is dry, and avoid the influence of ambient temperature and heating power.

The method for judging the dryness of the dried object of the dryer provided by the present invention includes:

11) Detect the ambient temperature Ts;

12) Detect the temperature Tc of the air outlet of the dryer;

13) Calculate the difference Tc-Ts between the temperature measured in step 12) and the temperature measured in step 11);

14) compare the difference in step 13) with a predetermined value To; when the difference is greater than the predetermined value, enter the next step:

15) Judging that the object to be dried has been dried.

Preferably, between the step 14) and the step 15), it is further included to wait for a certain time Io before entering the next step.

Preferably, said step 14) and said step 15) also include:

31) Detect the air inlet temperature value Tj;

32) Calculate the difference Tj-Tc between the air inlet temperature value Tj measured in step 31) and the air outlet temperature value Tc obtained by detection in step 12);

33) Compare the difference obtained in step 32) with the predetermined value Td; if the measured difference is smaller than the predetermined value Td, enter the next step.

Preferably, the predetermined value Td is determined according to the weight of the dried object; the heavier the dried object, the greater the predetermined value Td.

Preferably, the detected ambient temperature in step 11) can be detected by a special temperature sensor, or the air outlet temperature before the dryer works can be used as the ambient temperature value, or the air inlet temperature before the dryer works can be used The average value of the air outlet temperature and the air outlet temperature is used as the ambient temperature value.

The dryer drying judging device provided by the present invention includes:

The temperature sensor (RT1) installed at the air outlet of the dryer;

The control unit is used to receive the detection signal obtained by the temperature sensor (RT1), convert the signal into a temperature value; and make a decision on whether the dried object is dry according to the difference between the measured temperature and the ambient temperature Ts Judging; when the difference is greater than the predetermined value To, it is judged that the object to be dried has been dried.

Preferably, a temperature sensor (RT2) is also included, installed at a position away from the air duct, for detecting the ambient temperature.

Preferably, it also includes a temperature sensor (RT3), which is installed at the air inlet of the dryer for detecting the temperature Tj of the air inlet; when the control unit performs drying judgment, it also includes a temperature sensor (RT3) to detect The difference between the air inlet temperature Tj and the air outlet temperature Tc detected by the temperature sensor ( RT1 ) is compared with a predetermined value Td, and when the difference is smaller than the predetermined value Td, it is judged that the object to be dried has been dried.

Preferably, the temperature sensor is a resistance temperature sensor or a voltage temperature sensor or a current temperature sensor.

Preferably, the resistance temperature sensor is connected in series with other resistors to divide the voltage, and the divided voltage is input as a detection signal to the input port of the control unit; the input port of the control unit is an analog-to-digital conversion port.

The basic idea of the present invention is to use the temperature drop caused by water evaporation during drying to judge whether the dried object is dry. Different from the closest prior art that uses temperature values to judge drying, the detection device and method provided by the present invention compare the detected temperature of the air outlet with the ambient temperature to obtain a better judgment effect, and can be conveniently used in dryers control.

At the same time, in the preferred mode of the present invention, the temperature sensors respectively installed at the air inlet and the air outlet are used, and the temperature difference between the two temperature sensors is used for drying judgment, so as to avoid the influence of factors such as the temperature change of the heating wire of the dryer on the drying judgment , so that the judgment result is more accurate, and it is suitable for occasions that require higher judgment precision.

Description of drawings

Fig. 1 is the circuit diagram of the first embodiment of the present invention;

Fig. 2 is a flow chart of the drying judging method of the first embodiment of the present invention;

Fig. 3 is a flow chart of the dryer control method according to the first embodiment of the present invention;

Fig. 4 is the circuit diagram of the second embodiment of the present invention;

Fig. 5 is a flow chart of a drying judging method according to the second embodiment of the present invention;

Fig. 6 is a flowchart of a dryer control method according to the second embodiment of the present invention;

Fig. 7 is a circuit diagram of another connection mode of the temperature sensor in the embodiment of the present invention;

Fig. 8 is a circuit diagram of another connection mode of the temperature sensor in the embodiment of the present invention.

Detailed ways

Please refer to FIG. 1 , which is a circuit diagram of the first embodiment of the present invention.

The drying detection device of the dryer includes a detection circuit and a single-chip microcomputer (not shown in the figure).

The detection element of the detection circuit is a temperature sensor, including a temperature sensor RT1 and a temperature sensor RT2. The temperature sensor RT1 is installed at the air outlet of the dryer for detecting the temperature of the air outlet. The temperature sensor RT2 is installed at a position not affected by the work of the dryer, such as the base of the dryer, to detect the ambient temperature, or the temperature sensor RT2 may not be installed, and the temperature sensor RT1 may be used before the dryer starts to work. The temperature detection value is used as the ambient temperature value. The structure of the detection circuit is as follows:

The terminal 1 of the temperature sensor RT1 is connected to the positive pole AV+ of the power supply, the terminal 2 is connected to the power supply ground through the resistor R1, and connected to the input port A of the power microcontroller through the resistor R3. The input port A is an AD conversion port of the single chip microcomputer.

A diode D1 is connected between the terminal 2 and the terminal 1 of the temperature sensor RT1 , the cathode of the diode is connected to the terminal 1 , and the anode is connected to the terminal 2 .

A capacitor C1 is connected between the input terminal A of the microcontroller and the power ground.

The working principle of this detection circuit is: the temperature sensor RT1 and the resistor R1 are connected in series between the positive pole of the power supply and the power ground, and the resistance value of the temperature sensor changes with the change of temperature. Therefore, the voltage at the sampling point M in Fig. 1 varies with The resistance value of the temperature sensor RT1 changes to generate different sampling voltages. The sampling voltage enters the input terminal A of the single-chip microcomputer through the resistor R3, and becomes a digital value through AD conversion, which is received and processed by the processor of the single-chip microcomputer to convert it into a temperature value. The resistor R3 is the input resistor of the input terminal A of the single chip microcomputer, and is used to protect the input port. The function of the diode D1 is to provide a path for the interference signal whose voltage exceeds the power supply voltage AV+, so as to prevent it from damaging the input terminal A of the single-chip microcomputer; since the temperature sensor RT1 is connected at the far end, it is easier to introduce higher voltage interference, Therefore, it is necessary to use this diode to prevent interference from entering the microcontroller terminals. The function of the capacitor C1 is to filter out the high-frequency interference that may enter the input terminal A.

The detection circuit structure and working principle of the temperature sensor RT2 are exactly the same as those described above, and will not be repeated here.

Please refer to Figure 2, which shows the process of using the above-mentioned detection circuit to judge dryness.

Step S200, start.

Step S201, detecting the ambient temperature Ts when the dryer is working. The specific detection method is to read the temperature detection signal of the temperature sensor RT2, and convert it into a temperature value by the corresponding processing such as linearization by the single-chip microcomputer. If the special ambient temperature detection sensor RT2 is not installed, the temperature value detected by the temperature sensor RT1 before the dryer starts to work can be used as the ambient temperature when the dryer is working. Since the ambient temperature will not change too much, so Taking this value as the ambient temperature value generally does not cause large errors in subsequent drying judgments.

Step S202, detecting the tuyere temperature Tc. The detection method of the temperature is to read the temperature detection signal of the temperature sensor RT1 installed at the air outlet, and obtain the temperature value through corresponding processing such as linearization by the single-chip microcomputer.

Step S203, judging whether the difference Ts between the air outlet temperature detection value Tc and the ambient temperature is higher than a predetermined value To. If yes, go to step S204; if not, go back to step S201.

Step S204, start timing. Before starting timing, first reset the timer to zero. Design time is I.

After satisfying the Tc-Ts>To judgment condition, the dried object needs to be dried for a period of time before it can be completely dried, and, due to various reasons, the judgment condition may no longer be satisfied. It should be ensured that the drying conditions are met stably and last for a certain period of time. Here, the design time is I, and the required duration condition is Io.

Step S205, detecting the ambient temperature value Ts.

Step S206, detecting the tuyere temperature Tc.

Step S207, judging whether the difference between the air outlet temperature Ts and the ambient temperature detection value Tc is higher than the predetermined value To. If yes, go to step S208; if not, go back to step S201.

If Ts-Tc<To, it means that the air outlet temperature Tc cannot stably satisfy the drying judgment condition, and it should return to the state of starting detection.

Step S208, judging whether the counted time I is greater than a predetermined time Io. If yes, go to step S210; if not, go to step S209.

Step S209, continue timing, and return to step S205.

Step S210, judging that the dried object has been dried.

In short, the present invention uses a temperature sensor to measure the temperature at the air outlet of the dryer, and compares it with the ambient temperature, and compares the obtained temperature difference with the corresponding predetermined value as a basis for judging whether the dried object is dry. The specific conditions for judging (ie, the predetermined value To and the duration Io) are selected according to the conditions of the dried object. In order to obtain accurate judgment results, experiments can be carried out in order to select appropriate To and Io.

Please refer to FIG. 3 , which is a flow chart of controlling the work of the dryer by using the above-mentioned drying judging device and method. This control process includes:

Step S301, preparation.

Step S302, determining the drying temperature according to the type of the drying object.

Different drying items have different requirements for drying temperature. For example, for the same clothes, the drying temperature of cotton fabric can reach 80°C, while the temperature of silk fabric cannot exceed 50°C. Therefore, the drying temperature should be determined so as not to damage the dried object or fail to achieve the drying effect. The drying temperature has both an upper limit and a lower limit in order to allow a certain error. The method for determining the drying temperature is that the user manually inputs the required temperature; or the user inputs the type of the object to be dried, and the dryer determines the drying temperature accordingly.

Step S303, start the fan and the heating wire, and start drying.

Step S304, drying.

Step S305, judging whether it has been dried. If yes, go to step S306; if not, go back to step S304.

The process and method of this judgment have been described above, and will not be repeated here.

Step S306, turn off the heating wire and wait for the clothes to cool down.

Since the dried object needs to be cooled, the heating wire is first turned off, and the fan continues to run to promote the cooling of the dried object.

Step S307, turn off the fan, and end the drying.

Set an appropriate cooling time, when the time is up, turn off the fan, and the cooling process is completed.

Please refer to FIG. 4 , which is a circuit diagram of the second embodiment of the present invention. This embodiment also uses a temperature sensor to detect dryness, and its circuit diagram is the same as that of the first embodiment, but the installation position of the temperature sensor is different. The connection and working principle of the circuit will not be repeated here. The two temperature sensors in this embodiment are respectively installed at the air outlet of the dryer and the air inlet of the dryer. In Figure 4, the temperature sensor RT1 is installed at the air outlet of the dryer to detect the temperature Tc of the air outlet of the dryer; The temperature sensor RT1 has exactly the same function as the temperature sensor RT1 in the first embodiment, so the same reference numerals as the first embodiment are used. The temperature sensor RT3 is installed at the air inlet of the dryer to detect the temperature Tj of the air inlet. Similarly, the special temperature sensor RT2 installed in a suitable position can be used to detect the ambient temperature Ts, and the temperature sensor RT1 and the temperature sensor RT3 can also be used to detect the ambient temperature before the dryer starts to work. In this embodiment, the temperature sensor RT1, temperature The sensor RT3 detects the ambient temperature Ts.

Please refer to FIG. 5 , which is a flowchart of the second embodiment of the present invention. Parameters having the same functions as those in the first embodiment use the same symbols.

Step S500, start.

Step S501, detecting the ambient temperature Ts before drying, that is, before starting to work. The specific detection method is to read the temperature detection signals of the temperature sensor RT1 and temperature sensor RT3 before the dryer works, and convert them into temperature values by linearization and other corresponding processing by the single-chip microcomputer, and average the two values as the ambient temperature. temperature Ts.

Step S502, after drying starts, detect the tuyere temperature Tc. The detection method of the temperature is to read the temperature detection signal of the temperature sensor RT1 installed at the air outlet, and obtain the temperature value through corresponding processing such as linearization by the single-chip microcomputer.

Step S503, judging whether the air outlet temperature detection value Tc is higher than the ambient temperature Ts by a predetermined value To. If yes, go to step S504; if not, go back to step S502.

The basis for the above judgment is that as the moisture content of the dried product decreases, the temperature drop caused by the vaporization of the water content will continue to decrease; correspondingly, the value of the air outlet temperature higher than the ambient temperature will continue to increase. Therefore, the difference between the air outlet temperature and the ambient temperature can be used as the condition for dry judgment. However, this judgment condition may be affected by changes in the heating temperature of the dryer, so it should not be used as the only basis for judgment.

Step S504, detecting the air inlet temperature Tj and the air outlet temperature Tc. For the detection method, see step S502.

Step S505, calculating whether the temperature difference measured by the two temperature sensors is smaller than a predetermined value Td. If yes, go to step S506; if not, go back to step S504.

The basis for the above judgment is that when the humidity of the dried product is high, more heat will be taken away by vaporization of the moisture, and the temperature Tc of the air outlet is much lower than the temperature Tj of the air inlet. When the moisture content of the dried product gradually decreases, less heat is taken away by the vaporization of the moisture, and the temperature Tc of the air outlet is lower than the temperature Tj of the air inlet. Therefore, a predetermined value Td can be set, and when the temperature difference is smaller than this value, it is judged that the dried object has been dried.

The predetermined value Td should be determined according to the type of the dried product and the quality of the dried product. Experimentation can be performed to choose an appropriate value. The heavier the weight of the dried object, the greater the predetermined value Td. This is because the heavier the weight of the dried object, the more heat will be taken away by the drying air of the dryer, and the temperature of the air inlet and air outlet will be higher. The larger the difference is.

Step S506, judging that the dried object has been dried.

In the above judging method, since the difference between the air outlet temperature Tc and the air inlet temperature Tj is used to judge the dryness, it can avoid the deviation of the dryness judgment caused by the temperature change of the heating wire of the dryer, and more accurately carry out Dry judgment.

Please refer to FIG. 6 , for the control process of the drying machine using the above-mentioned drying judging device and method. This control process includes:

Step S601, preparation.

This preparatory step consists in detecting the ambient temperature value Ts. The detection of the temperature value is to read the temperature measurement value of the temperature sensor before the drying starts, and average the measurement values of the two temperature sensors as the ambient temperature value.

Step S602, determining the drying temperature according to the type of the drying object.

Different drying items have different requirements for drying temperature. For example, for the same clothes, the drying temperature of cotton fabric can reach 80°C, while the temperature of silk fabric cannot exceed 50°C. Therefore, the drying temperature should be determined so as not to damage the dried object or fail to achieve the drying effect. The drying temperature has both an upper limit and a lower limit in order to allow a certain error.

Step S603, start the fan and the heating wire, and start drying.

Step S604, reading the temperature detection value.

The temperature detection value includes the air outlet temperature Tc detected by the temperature sensor RT1; and the air inlet temperature Tj obtained by the temperature sensor RT3.

Step S605, judging whether the temperature exceeds the limit. If yes, go to step S606; if not, go to step S607.

The judgment of the temperature exceeding the limit is to compare the air inlet temperature Tj with the determined drying temperature value. When the air inlet temperature Tj is greater than the upper limit or lower than the lower limit of the determined drying temperature, it is judged that the temperature exceeds the limit. The function of this step is to prevent the drying temperature from exceeding the set upper limit or being lower than the set lower limit, causing damage to the dried object or failing to achieve the drying effect.

Step S606, adjusting the drying temperature.

Since the drying temperature exceeds the upper temperature limit, it will cause damage to the dried object, so the power of the heating wire should be reduced to lower the drying temperature. On the contrary, when the drying temperature is lower than the lower limit of the set temperature, the power of the heating wire is increased to increase the drying temperature so as to complete the drying process as soon as possible. After this step is completed, return to step S605.

In step S607, a dryness judging program is performed to judge whether the dried object has been dried. If yes, go to step S608; if not, go back to step S604.

The dryness judgment process has been described above, and will not be repeated here.

Step S608, turn off the heating wire and wait for the clothes to cool down.

Since the dried object needs to be cooled, the heating wire is first turned off, and the fan continues to run to promote the cooling of the dried object.

Step S609, turn off the fan, and end the drying.

An appropriate cooling time can be set, and when the time is up, the fan is turned off and the cooling process is completed.

It should be noted that the connection manners of the temperature sensors in the circuit diagrams of the above embodiments may vary.

Please refer to FIG. 7 , which shows another connection mode of the temperature sensor in the present invention.

In this circuit, no diode is connected between the two terminals of the temperature sensor. This circuit is suitable for situations with less interference.

Please refer to FIG. 8 , which shows another connection mode of the temperature sensor in the present invention.

In this embodiment, no diode is connected between the two terminals of the temperature sensor, but a capacitor is connected, and the function of the capacitor is also to filter high-frequency interference.

The temperature sensors used in the above-mentioned embodiments are all resistance temperature sensors, and other types of temperature sensors can also be used, and according to the type of sensor used, an appropriate input circuit is used to input the measurement signal to a control unit such as a single-chip microcomputer, so that the control unit can obtain Temperature information, so use this method to judge drying. For example, a voltage-type or current-type temperature sensor is used to convert the signal into a voltage-divided signal similar to the above-mentioned embodiment, and the purpose of temperature detection can also be achieved.

The above is only a preferred embodiment of the present invention, it should be pointed out that, for those of ordinary skill in the art, without departing from the principle of the present invention, some improvements and modifications can also be made, and these improvements and modifications can also be made. It should be regarded as the protection scope of the present invention.

Claims (10)

1, a kind of method of judging drying machine drying thing drying is characterized in that, comprising:

11) testing environment temperature T s;

12) detect dryer air outlet temperature T c;

13) calculate the difference Tc-Ts of the measured temperature of measured temperature of step 12) and step 11);

14) described difference of step 13) and predetermined value To are compared; When described difference during, then enter next step greater than this predetermined value:

15) judge by oven dry thing drying.

2, method according to claim 1 is characterized in that, also comprise between described step 14) and the described step 15) wait for a time Io who determines after, just enter next step.

3, method according to claim 1 is characterized in that, also comprises between described step 14) and the described step 15):

31) detect intake air temperature value Tj;

32) calculation procedure 31) measured intake air temperature value Tj, the difference Tj-Tc of the air outlet temperature value Tc that detect to obtain with step 12);

33) with step 32) difference and the predetermined value Td comparison that obtain; If the difference that records then enters next step less than this predetermined value Td.

4, method according to claim 3 is characterized in that, described predetermined value Td determines according to the weight of oven dry thing; The weight of oven dry thing is heavy more, and then described predetermined value Td is big more.

5, method according to claim 1, it is characterized in that, the testing environment temperature of described step 11), can detect by special temperature sensor and obtain, also can be with the air outlet temperature before the dryer work as ambient temperature value, perhaps with the mean value of intake air temperature before the dryer work and air outlet temperature as ambient temperature value.

6, a kind of drier judgment means is characterized in that, comprising:

Be installed on the temperature sensor (RT1) of dryer air outlet;

Control module is used to receive described temperature sensor (RT1) and detects the detection signal that obtains, and this signal is converted to temperature value; And whether drying is made judgement according to the difference of measured temperature and environment temperature Ts quilt to be dried thing; When described difference during, then judge by the oven dry thing dry greater than predetermined value To.

7, device according to claim 6 is characterized in that, also comprises temperature sensor (RT2), is installed on the position away from the air channel, is used for the testing environment temperature.

8, device according to claim 6 is characterized in that, also comprises temperature sensor (RT3), is installed on the position of dryer air inlet, is used to detect intake air temperature Tj; When described control module carries out the drying judgement, the difference that also comprises intake air temperature Tj that described temperature sensor (RT3) is detected and the air outlet temperature T c of described temperature sensor (RT1) detection, compare with predetermined value Td, when described difference during, then judge by the oven dry thing dry less than this predetermined value Td.

9, device according to claim 6 is characterized in that, described temperature sensor is resistor-type temperature sensor or voltage-type temperature sensor or ic temperature transducer.

10, device according to claim 6 is characterized in that, the described resistor-type temperature sensor dividing potential drop of connecting with other resistance, and dividing potential drop is input to the input port of control module as detection signal; This control module input port is the analog-to-digital conversion port.

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