CN112738923A

CN112738923A - Electric heating product

Info

Publication number: CN112738923A
Application number: CN202110070532.2A
Authority: CN
Inventors: 黄招平; 宋佳琦; 谢振华
Original assignee: Aukey Technology Co Ltd
Current assignee: Aukey Technology Co Ltd
Priority date: 2021-01-19
Filing date: 2021-01-19
Publication date: 2021-04-30

Abstract

The embodiment of the invention discloses an electric heating product which comprises a heating device, a temperature detection module, a switch module and a control unit, wherein the heating device comprises a PTC heating wire and an induction wire, the first end of the PTC heating wire is connected with a live wire of an alternating current power supply, the second end of the PTC heating wire is grounded through the switch module, the temperature detection module is connected with two ends of the induction wire and used for detecting the current heating temperature of the heating device, the control unit is respectively connected with the temperature detection module and the switch module, and the control unit is used for outputting a control signal to control the duty ratio of the switch module according to the current heating temperature of the heating device so as to control the heating temperature of the heating device. Through the mode, the temperature of the electric heating product can be controlled to be in a stable state.

Description

Electric heating product

Technical Field

The invention relates to the technical field of temperature control, in particular to an electric heating product.

Background

At present, most of the existing temperature controllers are applied to traditional electric heating products, and the traditional electric heating products need to be provided with the temperature controllers to achieve the temperature control effect, and are widely applied to heating pads or electric blankets in families, physical therapy places and office places.

However, the existing temperature controller has a simple temperature control process, which results in large temperature fluctuation of electric heating products and easy damage to the electric heating products.

Disclosure of Invention

The embodiment of the invention aims to provide an electric heating product, which can control the heating temperature of the electric heating product to be in a stable state.

In order to achieve the above object, the present invention provides an electric heating product comprising:

the device comprises a heating device, a temperature detection module, a switch module and a control unit;

the heating device comprises a PTC heating wire and an induction wire, wherein a first end of the PTC heating wire is connected with a live wire of an alternating current power supply, and a second end of the PTC heating wire is grounded through the switch module;

the temperature detection module is connected with two ends of the induction line and is used for detecting the current heating temperature of the heating device;

the control unit is respectively connected with the temperature detection module and the switch module, and is used for outputting a control signal to control the duty ratio of the switch module according to the current heating temperature of the heating device so as to control the heating temperature of the heating device.

In an optional manner, the control unit is configured to output a control signal to control a duty ratio of the switching module according to a current heating temperature of the heating device, so as to control the heating temperature of the heating device, and includes:

controlling the switch module at a first preset duty ratio to control the heating temperature of the heating device to increase to a first preset temperature;

controlling the switch module at a second preset duty ratio to control the heating temperature of the heating device to be reduced to a second preset temperature;

controlling the switch module at a third duty ratio to control the heating temperature of the heating device to be maintained within a range of a second preset temperature interval;

the first preset temperature is higher than the second preset temperature, the first preset duty ratio is higher than the second preset duty ratio, and the second preset duty ratio is higher than the third preset duty ratio.

In an optional manner, after the controlling the switching module at the third duty cycle to control the heating temperature of the heating device to be maintained within a range of a third preset temperature interval, the control unit is further configured to:

if the current heating temperature of the heating device is lower than the lowest temperature value in a second preset temperature interval, controlling the switch module with a fourth duty ratio, wherein the fourth duty ratio is larger than the third duty ratio;

and if the current heating temperature of the heating device is greater than the lowest temperature value of a second preset temperature interval, controlling the switch module with a fifth duty cycle, wherein the fifth duty cycle is smaller than the third duty cycle.

The first preset duty cycle control, the second preset duty cycle control and the third preset duty cycle control are one specific embodiment provided by the invention, the technology is not limited to the duty cycle control modes of more than or less than the three stages of preset temperatures, but the heating temperature is adjusted and controlled by the duty cycle control modes.

In an optional manner, the temperature detection module further includes a first voltage dividing circuit and a second voltage dividing circuit;

the first voltage division circuit is respectively connected with the first end of the induction line and the control unit, and the second voltage division circuit is respectively connected with the second end of the induction line and the control unit.

In an optional manner, the first voltage dividing circuit includes a first diode and a second diode, and a first resistor, a second resistor, a third resistor and a fourth resistor connected in series in this order;

the anode of the first diode is grounded, the cathode of the first diode is connected with the anode of the second diode, the cathode of the second diode is connected with the first power supply, the non-series end of the first resistor is connected with the first end of the induction line, the connecting point between the second resistor and the third resistor is connected with the cathode of the first diode and the control unit, and the non-series end of the fourth resistor is grounded.

In an optional manner, the second voltage division circuit includes a first voltage regulator diode, and a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, and a ninth resistor connected in series in this order;

the non-series end of the fifth resistor is connected with the second end of the induction line, the connecting point between the sixth resistor and the seventh resistor is connected with the anode of the first voltage stabilizing diode, the connecting point between the seventh resistor and the eighth resistor is connected with the control unit, and the cathode of the first voltage stabilizing diode and the non-series end of the ninth resistor are both grounded.

the plurality of temperature sensors comprise a first thermistor and a second thermistor;

the first voltage division circuit is respectively connected with the first thermistor and the control unit, and the second voltage division circuit is respectively connected with the second thermistor and the control unit.

the anode of the first diode is grounded, the cathode of the first diode is connected with the anode of the second diode, the cathode of the second diode is connected with the power module, the non-series end of the first resistor is connected with the first thermistor, the connecting point between the second resistor and the third resistor is connected with the cathode of the first diode and the control unit, and the non-series end of the fourth resistor is grounded.

the non-series end of the fifth resistor is connected with the second thermistor, a connecting point between the sixth resistor and the seventh resistor is connected with the anode of the first voltage stabilizing diode, a connecting point between the seventh resistor and the eighth resistor is connected with the control unit, and the cathode of the first voltage stabilizing diode and the non-series end of the ninth resistor are both grounded.

In an optional manner, the temperature detection module further includes a metering chip, where the metering chip includes a voltage analog input terminal and a data output terminal;

the voltage analog input end is connected with the second voltage division circuit, and the data output end is connected with the control unit.

In an optional mode, the switch module comprises a first thyristor and a first switch tube;

the control end of the first silicon controlled rectifier is connected with the second end of the first switch tube, the two ends of the non-control end of the first silicon controlled rectifier are respectively connected with the ground and the second end of the PTC heating wire, the first end of the first switch tube is connected with a first power supply, and the control end of the first switch tube is connected with the control unit.

In an optional mode, the electric heating product further comprises an abnormality detection module;

the abnormality detection module is connected with a second end of the PTC heating wire, and the abnormality detection module is used for detecting whether the heating device is abnormal or not.

In an alternative mode, the abnormality detection module includes a second switching tube;

the control end of the second switch tube is connected with the second end of the PTC heating wire, the first end of the second switch tube is grounded, and the second end of the second switch tube is connected with the first power supply and the control unit respectively.

The embodiment of the invention has the beneficial effects that: the invention provides an electric heating product, which comprises a heating device, a temperature detection module, a switch module and a control unit, wherein the heating device comprises a PTC heating wire and an induction wire, the first end of the PTC heating wire is connected with a live wire of an alternating current power supply, the second end of the PTC heating wire is grounded through the switch module, the temperature detection module is connected with two ends of the induction wire and used for detecting the current heating temperature of the heating device, the control unit is connected with the temperature detection module and the switch module, and the control unit is used for outputting a control signal to control the duty ratio of the switch module according to the current heating temperature of the heating device so as to control the heating temperature of the heating device.

Drawings

One or more embodiments are illustrated by way of example in the accompanying drawings, which correspond to the figures in which like reference numerals refer to similar elements and which are not to scale unless otherwise specified.

FIG. 1 is a schematic structural diagram of an electric heating product and an AC power supply according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a heating device according to an embodiment of the present invention;

fig. 3 is a schematic circuit diagram of a temperature detection module according to an embodiment of the present invention;

fig. 4 is a schematic circuit diagram of a switch module according to an embodiment of the present invention;

FIG. 5 is a schematic structural view of an electric heating product according to another embodiment of the present invention connected to an AC power supply;

fig. 6 is a schematic circuit diagram of an anomaly detection module according to an embodiment of the present invention;

fig. 7 is a flowchart of a process of controlling a heating temperature of a heating device according to an embodiment of the present invention;

FIG. 8 is a schematic diagram of a control signal for controlling a heating device according to an embodiment of the present invention;

FIG. 9 is a schematic diagram of a temperature control curve provided by an embodiment of the present invention;

FIG. 10 is a schematic diagram of a control signal for controlling a heating device according to another embodiment of the present invention;

fig. 11 is a flowchart of a process of controlling a heating temperature of a heating device according to another embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, fig. 1 is a schematic structural diagram of an electric heating product connected to an ac power supply according to an embodiment of the present invention, as shown in fig. 1, the electric heating product includes a heating device 10, a temperature detection module 20, a control unit 30 and a switch module 40, wherein the heating device 10 includes a PTC heating wire 11 and an induction wire 12, a first end of the PTC heating wire 11 is connected to a live wire of the ac power supply 300, a second end of the PTC heating wire 11 is grounded through the switch module 40, the temperature detection module 20 is connected to two ends of the induction wire 12, and the control unit 30 is respectively connected to the temperature detection module 20 and the switch module 40.

Wherein, the heating device 10 can be a heating pad, an electric blanket, or a shawl, a neckerchief, a belt, etc. which can be electrically heated.

Specifically, the temperature detecting module 20 is used for detecting the current heating temperature of the heating device 10, referring to fig. 2, the heating device 10 has a heating wire with NTC characteristics, which includes a PTC heating wire 11, a sensing wire 12 and an NTC material layer 13, that is, when the temperature of the heating device 10 changes, the NTC material layer 13 induces a change in NTC resistance value due to the change in temperature, and the change is transmitted through the sensing wire 12. When the temperature detecting module 12 is connected to both ends of the sensing wire 12, the temperature variation of the heating device 10 can be obtained from the variation signal of the sensing wire 12. The control unit 30 is configured to output a control signal to control a duty ratio of the switch module 40 according to the current heating temperature of the heating device 10, so as to control the heating temperature of the heating device 10, where the duty ratio of the switch module 40 mainly refers to a ratio of a total time duration of each on and off of the switch module 40 to a total time duration. For example, when the switching module 40 is turned on for 4 seconds, turned off for 12 seconds, and then turned on again, the duty ratio at this time is 4/(4+12) ═ 4/16 ═ 4/16 ═ 25%.

In an embodiment, referring to fig. 3, fig. 3 is a schematic circuit structure diagram of an exemplary temperature detecting module 20. As shown in fig. 3, the temperature detecting module 20 further includes a first voltage dividing circuit 21 and a second voltage dividing circuit 22, wherein the first voltage dividing circuit 21 is connected to the first end of the sensing line 12 through the 2 nd pin of the interface J1, the first voltage dividing circuit 21 is connected to the control unit 30 through the interface S1, the second voltage dividing circuit 22 is connected to the second end of the sensing line 12 through the 3 rd pin of the interface J1, and the second voltage dividing circuit 22 is connected to the control unit 30 through the interface S2.

Optionally, the first voltage dividing circuit 21 includes a first diode D1 and a second diode D2, and a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4 connected in series in this order.

The anode of the first diode D1 is grounded, the cathode of the first diode D1 is connected to the anode of the second diode D2, the cathode of the second diode D2 is connected to the power module 30, the non-series end of the first resistor R1 is connected to the first end of the sensing line 12 through the 2 nd pin of the interface J1, the connection point between the second resistor R2 and the third resistor R3 is connected to the cathode of the first diode D1 and the control unit 30 through the interface S1, and the non-series end of the fourth resistor R4 is grounded to GND.

Specifically, the first end of the sensing line 12 forms a voltage dividing loop with the first resistor R1, the second resistor R2, the third resistor R3 and the fourth resistor R4 through the 2 nd pin of the interface J1, and the voltage output by the interface S1 depends on the voltage division of the third resistor R3 and the fourth resistor R4. With the temperature change, the sensing line 12 senses the change of the NTC resistance, so as to drive the divided voltages of the third resistor R3 and the fourth resistor R4 to change accordingly, and therefore, the control unit 30 can know the actual temperature change of the heating apparatus 10 by receiving the voltage output by the interface S1. The first diode D1 and the second diode D2 are used for clamping the divided voltage of the third resistor R3 and the fourth resistor R4 to prevent the voltage from abnormal fluctuation and affecting the subsequent control unit 30.

Optionally, the first divided voltage 11 further includes a capacitor C1, a capacitor C2, and a resistor R11, and the specific connection relationship is known in the drawings and is not described herein again, where the capacitor C1 and the capacitor C2 are used for filtering, and the capacitor R11 is used for limiting current.

Optionally, the second voltage dividing circuit 22 includes a first voltage stabilizing diode DW1, and a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, and a ninth resistor R9 connected in series in this order.

The non-series end of the fifth resistor R5 is connected to the second end of the sensing line 12 through the 3 rd pin of the interface J1, the connection point between the sixth resistor R6 and the seventh resistor R7 is connected to the anode of the first zener diode DW1, the connection point between the seventh resistor R7 and the eighth resistor R8 is connected to the control unit 30 through the interface S2, and the cathode of the first zener diode DW1 and the non-series end of the ninth resistor R9 are both grounded to GND (ground)

Specifically, the second end of the sense line 12 forms a voltage dividing loop with the fifth resistor R5, the sixth resistor R6, the seventh resistor R7, the eighth resistor R8 and the ninth resistor R9 through the 3 rd pin of the interface J1, and the voltage output by the interface S2 depends on the voltage division of the eighth resistor R8 and the ninth resistor R9. With the temperature change, the sensing line 12 senses the change of the NTC resistance, so that the divided voltages of the eighth resistor R8 and the ninth resistor R9 are also changed accordingly. Therefore, the control unit 30 can know the actual temperature change of the heating apparatus 10 by receiving the voltage output from the interface S2. And the first zener diode DW1 also acts to clamp the voltage across it.

Optionally, the second voltage-dividing circuit 22 further includes a resistor R12, a resistor R13, a resistor R14, a resistor R15, a capacitor C3, and a capacitor C4, and the specific connection relationship is known in the drawings and is not described herein again, where the capacitor C3 and the capacitor C4 are both used for filtering, and the resistor R14 and the resistor R15 are used for current limiting.

In summary, two simultaneous temperature detection processes are provided in the temperature detection module 20 to further increase the accuracy of temperature detection.

Further, the temperature detection module 20 further includes a metering chip U2, wherein the metering chip U2 can be a metering chip of the type HLW8110, and the HLW8110 metering chip is a high-precision electric energy metering IC, which adopts a CMOS manufacturing process, is mainly used for single-phase metering applications, and can measure line voltage and current, and can calculate active power, apparent power and power factors.

The metering chip U2 has a voltage analog input terminal VP (i.e., the 3 rd pin), which is connected to the second voltage dividing circuit 22 for receiving the divided voltages of the eighth resistor R8 and the ninth resistor R9; the metrology chip U2 also has a data output TX (i.e., pin 6), which may then transmit the detected signal to the control unit 30 via the data output TX of metrology chip U2. More accurate temperature monitoring can be achieved through the metering chip U2.

In one embodiment, the circuit structure shown in fig. 4 can be used as the switch module 40 to control the heating device 10.

As shown in fig. 4, the switch module 40 includes a switch Q1, a resistor R16, a resistor R17, and a thyristor U1 (a triac is used as an example of the thyristor), wherein a control end of the switch Q1 is connected to the control unit 30 through an interface S4, a first end of the switch Q1 is connected to the first power source V1, a second end of the switch Q1 is connected to one end of the resistor R17, the other end of the resistor R17 is connected to one end of the resistor R16 and a control end G of the thyristor U1, the other end of the resistor R16 is grounded, a T1 end and a T2 end of a non-control end of the thyristor 1 are respectively connected to a second end (through a 4 th pin of the interface J1) of the PTC heating line 11 of the heating apparatus 10 and a ground GND, i.e., a T1 end of the non-control end of the thyristor U1 is connected to a 4 th pin of the interface J1 in fig. 4.

Specifically, when the control unit 30 inputs a control signal to the switching tube Q1 through the interface S4, and if the control signal is a high level signal and turns on the switching tube Q1, the output voltage V1 of the power module 10 is input to the control end G of the thyristor U1 through the first end and the second end of the switching tube Q1 and the resistor R17, and at this time, the T1 end and the T2 end of the non-control end of the thyristor U1 are in a connected state, a loop where the heating device 10 and the thyristor U1 are located is a path, and the heating device 10 is powered. On the contrary, if the control signal input by the control unit 30 through the interface S4 is a low level signal and the switching transistor Q1 is turned off, the control end G of the thyristor U1 is grounded to GND through the resistor R16, the thyristor U1 is turned off, and at this time, the T1 end and the T2 end of the non-control end of the thyristor U1 are in a disconnected state, and the heating apparatus 10 is powered off. Further, the control unit 30 can also control the on-time of the switching tube Q1, i.e. the duty ratio of the switching tube Q1, by the control signal, so as to control the operation time of the heating device 10. For example, when the switching tube Q1 is turned off, if the temperature detecting module 20 detects that the temperature of the heating apparatus 10 is too high, the control unit 30 outputs the control signal to decrease the on-time of the switching tube Q1, i.e. control the duty ratio of the switching tube Q1 to decrease the temperature of the heating apparatus 10 again, so as to maintain the temperature 10 of the heating apparatus in a stable state.

In another embodiment, as shown in fig. 5, the electric heating product further includes an abnormality detection module 50, and the abnormality detection module 50 is connected to the second end of the PTC heater wire 11. The abnormality detection module 50 is used for detecting whether the heating device 10 is abnormal. For example, in one embodiment, the abnormality detection module 50 is used to detect whether an abnormality occurs in the connection between the heating device 10 and the power supply, or the abnormality detection module 50 is used to detect whether the heating device 10 has a fault, which causes an abnormal condition such as an open circuit.

In one embodiment, the circuit structure shown in fig. 6 may be used as the abnormality detection module 50 to detect whether an abnormality occurs in the heating apparatus 10.

As shown in fig. 6, the abnormality detection module 50 includes a switch Q2, a resistor R18, a resistor R19, a resistor R20, a resistor R21 and a diode D3, wherein a control end of the switch Q2 is connected to the heating apparatus 10 through the resistor R18, the resistor R19 and the diode D3, and is connected to a connection point between the heating apparatus 10 and the ground GND (i.e., connected to the T1 end of the thyristor U1 in fig. 4), a first end of the switch Q2 is grounded, a second end of the switch Q2 is connected to the first power source V1 through the resistor R20, and a second end of the switch Q2 is connected to the control unit 30 through the resistor R21 and the interface S5.

Specifically, if no abnormality occurs in the heating apparatus 10 and the circuit between the heating apparatus 10 and the ground is a path, the ac power supply 300 passes through the heating apparatus 10 and then is input to the control terminal of the switching tube Q2, and since the ac power supply 300 is ac power, when the circuit is not open, the switching tube Q2 is repeatedly switched between on and off with the change of the ac power supply 300. When the switch Q2 is turned on, the interface S5 is connected to the ground GND through the resistor R21, the second terminal and the first terminal of the switch Q2, that is, the voltage of the interface S5 is forced to be pulled low; when the switch Q2 is turned off, the interface S5 is connected to the first power source V1 through the resistor R21 and the resistor R20, i.e. the voltage of the interface S5 is forced to be high, so that the output of the interface S5 is a square wave signal in this case.

If the ac power supply 300 is abnormal and the loop between the ac power supply 300 and the ground is open, the input signal of the switching tube Q2 is always low level, the switching tube Q2 remains off, and S5 is connected to the first power supply V1 through the resistor R21 and the resistor R20, that is, the voltage of the interface S5 is forced to be high, and the interface S5 remains high. If the switching tube Q2 is abnormal and the mis-conduction occurs, the interface S5 is connected to the ground GND through the resistor R21 and the second end and the first end of the switching tube Q2, that is, the voltage of the interface S5 is forced to be pulled down, and the interface S5 is kept at a low level.

It should be noted that the hardware structure of the electric heating type product shown in fig. 1 or fig. 5 is only one example, and the electric heating type product may have more or less components than those shown in the figures, may combine two or more components, or may have different component configurations, and the various components shown in the figures may be implemented in hardware, software, or a combination of hardware and software including one or more signal processing and/or application specific integrated circuits. For example, the electric heating product may also be a sampling module, and the sampling module is used for sampling the current and power of the heating device 10.

Fig. 7 is a flowchart of a process of controlling a heating temperature of a heating device according to an embodiment of the present invention, where the control process may be performed by the electric heating product shown in fig. 1 or fig. 5, and as shown in fig. 7, the control process includes:

601: and controlling the switch module with a first preset duty ratio to control the heating temperature of the heating device to be increased to the maximum preset temperature.

602: and controlling the switch module at a second preset duty ratio to control the heating temperature of the heating device to be reduced to a second preset temperature.

603: and controlling the switch module with a third duty ratio to control the heating temperature of the heating device to be maintained within the range of a third preset temperature interval.

The first preset temperature is higher than the second preset temperature, the first preset duty ratio is higher than the second preset duty ratio, and the second preset duty ratio is higher than the third preset duty ratio. The heating temperature of the heating device can be controlled by controlling the duty ratio of the switch module, and if the duty ratio of the switch module is higher, namely the heating device is in a heating state (the heating device is powered on in the state) for a longer time, the heating temperature is also higher; on the contrary, if the duty ratio of the switch module is low, that is, the time that the heating device is in the sleep state (in which the heating device loses power) is long, the heating temperature is low.

In practical application, the switch module shown in fig. 4 is used for illustration, and the duty cycle of the switch module refers to the duty cycle of the switching tube Q1, that is, the on-time of the switching tube Q1 is the proportion of the total time of each switch. When the heating temperature is needed for heating, the heating temperature to be reached by the heating device needs to be preset, and the temperature is the second preset temperature.

When the heating device starts to heat, the switching tube Q1 is controlled to be turned on and off at a first preset duty ratio, and the first preset duty ratio is the maximum duty ratio in the control process, so that the heating temperature of the heating device is rapidly increased to a first preset temperature. When the current heating temperature of the heating device is detected to be the maximum preset temperature, the duty ratio is reduced from the first preset duty ratio to the second preset duty ratio, and at the moment, the heating temperature of the heating device is slowly reduced because the conducting time of the switching tube Q1 is shortened. When the heating temperature is reduced to the second preset temperature, the duty ratio is reduced from the second preset duty ratio to the third preset duty ratio, and at the moment, due to the influences of the environment temperature and the temperature of the heating device, the heating temperature of the heating device can be maintained in an interval containing the second preset temperature. Therefore, the temperature of the heating device is adjusted to the heating temperature which is originally preset and is to be reached by the heating device.

For example, please refer to fig. 9 in conjunction with fig. 8, wherein a curve L1 shown in fig. 8 is the whole process of a certain temperature control, and in fig. 8, the duty ratio before time T1 is greater than the duty ratio between time T1 and time T2, and the duty ratio between time T1 and time T2 is greater than the duty ratio after time T2, and meanwhile, the ON finger controls the signal that the switch Q1 is turned ON, and the OFF finger controls the signal that the switch Q1 is turned OFF. The heating temperature of the heating device is shown in fig. 9.

Assuming that the heating temperature to be reached by the preset heating device is Temp2, the second preset temperature is Temp2, and the first preset temperature is Temp 1. The switching tube Q1 is controlled at the maximum duty ratio (first preset duty ratio) before the temperature Temp1 so that the temperature of the heating device rapidly rises to Temp1 and reaches the temperature Temp1 at time T1. Then, the duty ratio is reduced to the second duty ratio, the second duty ratio is maintained when the heating temperature drops to Temp2, and the temperature Temp2 is reached at the second time T2. I.e. the second duty cycle is maintained between the time periods (T1, T2). Then, by continuing to decrease the duty ratio to the third duty ratio, the temperature can be maintained to fluctuate above and below the temperature Temp2, and the fluctuation range does not exceed the preset range. Thereby achieving control of the heating temperature of the heating device to the temperature Temp2 to be set.

It will be appreciated that depending on the heating temperature to be achieved by the control heating means, the second predetermined temperature may be determined, i.e. the duty cycle at which the final temperature is at steady state may be determined. As shown in fig. 10, the curves L2, L3 and L4 may represent three different temperatures, for example, 20 degrees, 30 degrees and 50 degrees, respectively, so that when the heating temperature of the heating device is in a relatively stable state, the corresponding duty ratios are as shown in the curves L2, L3 and L4. In one embodiment, the heating temperature of the heating device may be set to multiple steps, and each step corresponds to one duty cycle curve. For example, the heating temperature of the heating device can be set to a low gear, a medium gear and a high gear, each gear can correspond to the duty ratio in the curve L2, the curve L3 and the curve L4, respectively, so that the heating device can be at different heating temperatures by directly selecting different gears.

It can be seen from the foregoing embodiments that, when the switching tube Q1 is controlled by the second duty ratio to control the heating temperature of the heating device to be kept within the range of the second preset temperature interval, for example, if the heating temperature to be reached by the heating device is Temp2, the second preset temperature interval may be set to (Temp2-2, Temp2+2), and if the heating temperature does not exceed the interval, it can be considered that the heating temperature is in a relatively stable state at this time, and no adjustment is made.

It should be noted that, in this embodiment, three preset duty cycles are adopted to implement the temperature control process, and in other embodiments, other numbers of duty cycles with different parameters may also be adopted, which is not limited herein. Moreover, the variation curve of the heating temperature may change with the duty ratio parameter.

For example, in an embodiment, still taking the variation curve of the heating temperature shown in fig. 9 as an example, in order to make the transition more stable when the temperature reaches Tenp2, at least two different duty ratios may be set in the (T1, T2) time period, and the duty ratios may be reduced while the temperature is gradually reduced, so that the duty ratio when the temperature reaches Tenp2 is already relatively close to the third preset duty ratio, that is, at this time, at least four different preset duty ratios are adopted to realize the temperature control process.

For another example, in another embodiment, the temperature control process may also be implemented by using only two duty ratios, that is, firstly, the first duty ratio is used to gradually increase the temperature to the heating temperature to be reached, and then the first duty ratio is directly converted into the second duty ratio, so that the temperature is maintained to fluctuate up and down the heating temperature to be reached, and the fluctuation range does not exceed the preset range. Thereby also enabling a control process of the heating temperature.

However, if the heating temperature is in a stable state, the heating temperature exceeds a predetermined interval, for example, the heating temperature of the heating device may increase greatly due to a temperature change of the environment. At this time, the duty ratio of the control switch Q1 needs to be further adjusted. As shown in fig. 11, the adjustment process includes:

1001: and if the current heating temperature of the heating device is less than the lowest temperature value of the second preset temperature interval, controlling the switch module with a fourth duty ratio.

1002: and if the current heating temperature of the heating device is greater than the lowest temperature value of the second preset temperature interval, controlling the switch module at a fifth duty ratio.

Wherein the fourth duty cycle is greater than the third duty cycle, and the fifth duty cycle is less than the third duty cycle. If the heating temperature detected at a certain time is less than the maximum temperature of the second preset temperature interval, which indicates that the temperature is reduced more, the duty ratio needs to be increased to raise the temperature. Therefore, the switching tube Q1 needs to be controlled by a fourth duty ratio larger than the third duty ratio, so as to prolong the time for the heating device to get electricity, and further, the heating temperature of the heating device rises again to the range of the second preset temperature interval. And after the temperature rises again to the range of the second preset temperature interval, the duty ratio is restored to the third duty ratio again so as to keep the heating temperature of the heating device in a stable state and maintain the heating temperature in the range of the second preset temperature interval.

Similarly, if the heating temperature detected at a certain time is greater than the maximum temperature of the second preset temperature interval, it means that the temperature is increased more, and at this time, the duty ratio needs to be reduced to lower the temperature. Therefore, the switching tube Q1 needs to be controlled by a fifth duty ratio smaller than the third duty ratio, so that the time for the heating device to be powered is shortened, and the heating temperature of the heating device is decreased again and gradually decreased to the range of the second preset temperature interval. And after the temperature is reduced to the range of the second preset temperature interval again, the duty ratio is restored to the third duty ratio again so as to keep the heating temperature of the heating device in a stable state and maintain the heating temperature in the range of the second preset temperature interval.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; within the idea of the invention, also technical features in the above embodiments or in different embodiments may be combined, steps may be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An electric heating product, comprising:

2. The electric heating product according to claim 1, wherein the control unit is configured to output a control signal to control a duty ratio of the switching module according to a current heating temperature of the heating device, so as to control the heating temperature of the heating device, and the control unit comprises:

3. The electric heating product according to claim 2, wherein after the controlling the switching module at the third duty cycle to control the heating temperature of the heating device to be maintained within a range of a third preset temperature interval, the control unit is further configured to:

4. The electric heating-type product according to claim 1,

the temperature detection module further comprises a first voltage division circuit and a second voltage division circuit;

5. The electric heating-type product according to claim 4,

the first voltage division circuit comprises a first diode, a second diode, a first resistor, a second resistor, a third resistor and a fourth resistor which are sequentially connected in series;

6. The electric heating-type product according to claim 4,

the second voltage division circuit comprises a first voltage stabilizing diode, and a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor and a ninth resistor which are sequentially connected in series;

7. The electric heating-type product according to claim 4,

the temperature detection module also comprises a metering chip, and the metering chip comprises a voltage analog input end and a data output end;

8. The electric heating-type product according to claim 1,

the switch module comprises a first silicon controlled rectifier and a first switch tube;

9. The electric heating-type product according to claim 1,

the electric heating product also comprises an abnormality detection module;

10. The electric heating-type product according to claim 9,

the abnormality detection module comprises a second switch tube;