TW202106104A - Ceramic heating device and control method thereof which has an overheating protection mechanism to realize real-time detection and protection - Google Patents

Abstract

A ceramic heating device and a control method therefor are disclosed. The device includes a ceramic heating unit, a current sensing unit, a switch unit, and a control unit. The control method includes the steps of: controlling the switch unit to be turned on via the control unit, so as to make the ceramic heating unit receive an operating current to generate heat; detecting the intensity of the operating current by the current sensing unit and generating an output signal; getting the intensity of the operating current by the control unit based on the output signal. When the control unit determines that a slope value of the operating current varying with time is less than or equal to zero and determines that the operating current is less than a predetermined threshold, the switch unit is controlled to be non-conductive, so that the ceramic heating unit cannot receive the operating current; and therefore a real-time detection and protection mechanism can be realized.

Description

Ceramic heating device and control method

The invention relates to a heating device and a control method thereof, in particular to a ceramic heating device with an overheating protection mechanism and a control method.

A ceramic heating device is a device that uses positive temperature coefficient (PTC) ceramic heating sheets to generate heat, and is widely used in equipment such as bathroom heaters and indoor electric heaters. Existing ceramic heating devices use a temperature sensor to detect the temperature of the ceramic heating sheet, such as the temperature of the outer casing, so that when the device fails, the power is cut off to ensure the safety of users. For example, when the air duct of the bathroom heater is blocked or the motor fails, the heated warm air cannot be blown out smoothly, which will cause the temperature of the ceramic heating element of the heater to become higher and higher. When the temperature detected by the temperature sensor is determined by a control unit (such as a microcontroller) that the temperature exceeds a critical value, the control unit sends a control signal to disconnect the ceramic heating element and continue to receive current. Stop heating. Similarly, when the indoor electric heater is covered by clothes or quilts and the temperature rises abnormally, the same monitoring and protection mechanism is adopted. However, the conventional monitoring method using a temperature sensor not only indirectly detects the shell temperature of the ceramic heating element, but also is often easily damaged due to frequent switch operations. Therefore, there is room for improvement in the monitoring and protection mechanism of the conventional ceramic heating device.

Therefore, the purpose of the present invention is to provide a ceramic heating device with an overheating protection mechanism and a control method.

Therefore, according to one aspect of the present invention, a ceramic heating device is provided, which is suitable for a voltage source and includes a ceramic heating unit, a current sensing unit, a switch unit, and a control unit.

The ceramic heating unit is electrically connected to the voltage source to receive an operating current to generate heat. The current sensing unit is electrically connected between the voltage source and the ceramic heating unit to detect the magnitude of the operating current received by the ceramic heating unit, and then generate a corresponding output signal.

The switch unit is electrically connected between the voltage source and the ceramic heating unit, and includes a first end electrically connected to the voltage source, a second end electrically connected to the ceramic heating unit, and a control signal receiving a control signal Terminal, and control the conduction or non-conduction between the first terminal and the second terminal according to the control signal.

The control unit is electrically connected to the current sensing unit and the switch unit, and generates the control signal so that the switch unit controls the conduction between the first terminal and the second terminal, and receives the output from the current sensing unit Signal to obtain the magnitude of the operating current. When the control unit determines that a slope value of the operating current changes with time is less than or equal to zero, and determines that the operating current is less than a set threshold, the control signal is generated so that the switch unit controls the first terminal and the second terminal There is no conduction between them.

In some embodiments, the control unit calculates a change in the magnitude of the operating current during the predetermined time period according to the output signal every predetermined time period to obtain the slope value.

In other embodiments, the set threshold is equal to a maximum value of the operating current multiplied by a predetermined coefficient, and the predetermined coefficient is between 0 and 1.

In some embodiments, the control unit pre-stores the maximum value corresponding to the operating current of the ceramic heating unit, or the control unit obtains the value of the operating current according to the received output signal The maximum value.

In some other embodiments, when the control unit determines that the operating current is less than a threshold after turning on at a predetermined time after being turned on, the control signal is generated so that the switch unit controls the first terminal There is no conduction with the second terminal, and the threshold after startup is related to a maximum value of the operating current.

In other embodiments, the ceramic heating device further includes an alarm unit, which is electrically connected to the control unit. When the control unit generates the control signal, the switch unit controls the error between the first terminal and the second terminal. When turned on, the alarm unit is controlled to send out an alarm notification, and the alarm notification includes at least one of a warning sound and a warning light.

Therefore, according to another aspect of the present invention, there is provided a control method suitable for a ceramic heating device, the ceramic heating device comprising a ceramic heating unit, a current sensing unit, a switch unit, and a control unit. The control method Including steps (a) ~ (c).

In step (a), the control unit controls the switching unit to be turned on, so that the ceramic heating unit receives an operating current and generates heat.

In step (b), the current sensing unit detects the magnitude of the operating current to generate a corresponding output signal.

In step (c), the control unit obtains the magnitude of the operating current according to the output signal. When the control unit determines that a slope value of the operating current changes with time is less than or equal to zero, and determines that the operating current is less than a set value When the threshold is set, the switch unit is controlled to be non-conductive, so that the ceramic heating unit cannot receive the operating current.

In some embodiments, in step (c), the control unit calculates a change in the magnitude of the operating current in the predetermined time period according to the output signal every predetermined time period to obtain the slope value.

In other embodiments, the set threshold is equal to a maximum value of the operating current multiplied by a predetermined coefficient, and the predetermined coefficient is between 0 and 1.

In some embodiments, in step (c), the control unit pre-stores the maximum value corresponding to the operating current of the ceramic heating unit, or the control unit according to the received output signal, Obtain the maximum value of the operating current.

In other embodiments, in step (c), when the control unit determines that the operating current is less than a threshold after turning on for a predetermined time after turning on, the control signal is generated to make the The switch unit controls the non-conduction between the first terminal and the second terminal, and the threshold after activation is related to a maximum value of the operating current.

In other embodiments, the ceramic heating device further includes an alarm unit, wherein, in step (c), when the control unit controls the switch unit to be non-conducting, the alarm unit is also controlled to send an alarm notification, the The alarm notification includes at least one of a warning sound and a warning light.

The effect of the present invention is that the control unit controls the switching unit not to conduct when determining that the slope value is negative and the operating current is less than the set threshold value according to the operating current measured by the current sensing unit Stopping the supply of the operating current to the ceramic heating unit can avoid permanent damage to the ceramic heating device.

Before the present invention is described in detail, it should be noted that in the following description, similar elements are denoted by the same numbers.

1, an embodiment of the ceramic heating device of the present invention is suitable for a voltage source VIN, and includes a ceramic heating unit 2, a current sensing unit 3, a switch unit 4, a control unit 1, and an alarm unit 5.

The switch unit 4 includes a first terminal 41, a second terminal 42 electrically connected to the switch unit 4, and a control terminal 43 electrically connected to the control unit 1 to receive a control signal, and according to the control signal, for example, according to The voltage value or logic value of the control signal controls the conduction or non-conduction between the first terminal 41 and the second terminal 42. The switch unit 4 is, for example, a relay, but not limited to this.

The ceramic heating unit 2 is electrically connected to the voltage source VIN and the switch unit 4. When the first terminal 41 and the second terminal 42 of the switch unit 4 are turned on, it receives an operating current from the voltage source VIN, And then heat up. The ceramic heating unit 2 includes at least one ceramic heating sheet, and when the operating current flows through the at least one ceramic heating sheet, the at least one ceramic heating sheet generates heat and causes the temperature to rise. Referring again to FIG. 2, FIG. 2 exemplarily depicts the corresponding relationship between the operating current and temperature of the ceramic heating unit 2.

The current sensing unit 3 is electrically connected between the voltage source VIN and the first terminal 41 of the switch unit 4 to detect the magnitude of the operating current received by the ceramic heating unit 2 to generate a corresponding output signal. For example, the current sensing unit 3 converts the detected magnitude of the operating current into a voltage value of the output signal, but it is not limited to this.

The alarm unit 5 is electrically connected to the control unit 1 and is controlled to issue an alarm notification. The alarm notification includes a warning sound or a warning light, or the warning sound or the warning light. The alarm unit 5 is, for example, a buzzer and a light-emitting element.

The control unit 1 is electrically connected to the current sensing unit 3 and the control terminal 43 of the switch unit 4, and generates the control signal so that the switch unit 4 controls the conduction between the first terminal 41 and the second terminal 42, And receiving the output signal from the current sensing unit 3 to obtain the magnitude of the operating current. More specifically, the control unit 1 records or stores the magnitude of the operating current according to the output signal every predetermined time period. The predetermined time period is, for example, 1 second, or other time lengths, such as less than 10 seconds. Within, but not limited to this.

When the control unit 1 determines that the magnitude of the operating current is less than a post-turn-on threshold within a predetermined time after being turned on, the control signal is generated so that the switch unit 4 controls the gap between the first terminal 41 and the second terminal 42 No conduction. The predetermined time after the opening is, for example, 10 seconds. The post-start threshold is related to a maximum value of the operating current, and the post-start threshold is, for example, 25% of the maximum value. In other words, the control unit 1 judges whether the ceramic heating device is abnormal by judging the magnitude of the operating current at the 10th second point after the ceramic heating device is turned on, and when it determines the abnormality, it controls the The switch unit 4 is not turned on, so that the ceramic heating unit 2 no longer receives the operating current to stop heating, and controls the alarm unit 5 to send out the alarm notification to warn the surrounding users that the ceramic heating device is abnormal.

When the control unit 1 determines that a slope value of the operating current changes with time is less than or equal to zero, and determines that the operating current is less than a set threshold, it generates the control signal so that the switch unit 4 controls the first terminal 41 and the There is no conduction between the second ends 42. Following the previous example, the control unit 1 calculates the slope value every 1 second. For example, if the operating current is 1450mA, 1500mA, 1300mA in the first second, second second, and third second, then the slope value The calculated results in the second and third seconds are 50mA/sec and -200mA/sec, then the slope value in the third second is less than or equal to zero. The set threshold is equal to a maximum value of the operating current multiplied by a predetermined coefficient, and the predetermined coefficient is between 0 and 1, preferably between 0.6 and 0.7.

In this embodiment, the control unit 1 pre-stores the maximum value of the operating current, and referring to FIG. 2 again, the maximum value is 1500 mA, the predetermined coefficient is, for example, 0.7, and the set threshold is 1050 mA. When the ceramic heating unit 2 is turned on and heats up, it rises from room temperature to a set temperature (the set temperature is less than or equal to 200 degrees). At this time, the corresponding operating current is less than the maximum value (ie, 1500 mA). When the ceramic heating device is abnormal, the temperature of the ceramic heating unit 2 continues to rise from 200 degrees to 225 degrees. At this time, the slope value is negative and the operating current (i.e., 850mA) is less than the set threshold value (i.e., 1050mA). ), the control unit 1 controls the switch unit 4 to be non-conducting, so that the ceramic heating unit 2 no longer receives the operating current and stops heating, and controls the alarm unit 5 to send out the alarm notification to warn the surrounding users, the An abnormality has occurred in the ceramic heating device.

In other embodiments, the control unit 1 may also obtain the maximum value of the operating current according to the received output signal. For example, the control unit 1 updates the maximum value of the operating current at any time according to the output signal. Referring again to FIG. 2, when the ceramic heating unit 2 is turned on, it heats up and generates heat, such as from room temperature to Between 200 degrees, at this time, the control unit 1 can update the maximum value as the obtained operating current gradually increases. On the other hand, when the ceramic heating device is abnormal, the temperature of the ceramic heating unit 2 continues to rise from 200 degrees to 225 degrees. At this time, the corresponding operating current also drops from 1500 mA to 850 mA. However, the maximum The value is still maintained at the maximum value (ie) 1500mA, and the set threshold value is also maintained at 1050mA.

In addition, it should be specifically supplemented that: in this embodiment, the operating current is not limited to direct current or alternating current, and can be implemented accordingly. Furthermore, in other embodiments, the current sensing unit 3 and the switch unit 4 can also be electrically connected at different positions, as long as the current sensing unit 3 is electrically connected to the voltage source VIN and the ceramic heating unit 2 The magnitude of the operating current can be detected occasionally, and the switch unit 4 is electrically connected between the voltage source VIN and the ceramic heating unit 2 to control the ceramic heating unit 2 to receive or not receive the operating current.

1 and FIG. 2, FIG. 2 exemplarily illustrates a flow chart of a control method implemented by the ceramic heating device of the present invention. The control method includes steps S1 to S3.

In step S1, the control unit 1 determines whether the ceramic heating device is turned on, for example, the user turns it on or off, that is, when the control unit 1 determines that it is turned on, the control unit 1 controls the switch unit 4 to be turned on, so that the The ceramic heating unit 2 receives the operating current to generate heat. Then, step S2 is executed. Conversely, when the control unit 1 determines that it is not turned on, it returns to the starting position.

In step S2, the current sensing unit 3 detects the magnitude of the operating current to generate the corresponding output signal.

In step S3, the control unit 1 obtains the magnitude of the operating current according to the output signal. When the control unit 1 determines that the slope value of the operating current over time is less than or equal to zero, and determines that the operating current is less than the setting When the threshold is set, the switch unit 4 is controlled to be non-conductive, so that the ceramic heating unit 2 cannot receive the operating current. In more detail, step S3 includes sub-steps S30 to S34.

In sub-step S30, when the control unit 1 determines that the magnitude of the operating current is less than the post-turn-on threshold within a predetermined time after the turn-on, step S34 is executed.

In step S31, the control unit 1 calculates the change in the magnitude of the operating current in the predetermined time period according to the output signal every predetermined time period to obtain the slope value.

In step S32, the control unit 1 determines whether the slope value of the operating current change over time is less than or equal to zero. When it is judged that it is less than or equal to zero, the sub-step S33 is executed, and when it is judged to be greater than zero, the sub-step S2 is returned.

In step S33, the control unit 1 determines whether the operating current is less than the set threshold. When it is judged that it is less than the set threshold, sub-step S34 is executed, and when it is judged that it is greater than or equal to the set threshold, return to sub-step S2.

In step S34, the switch unit 4 is controlled to be non-conductive, so that the ceramic heating unit 2 cannot receive the operating current, and the alarm unit 5 is controlled to issue the alarm notification.

In summary, the present invention does not require a conventional temperature sensor to detect the temperature of the ceramic heating element, but uses the physical characteristics of the ceramic heating element itself, such as blockage of the air duct or motor failure of the heater in the bathroom, or The indoor electric heater is covered by clothing or quilts, so that the current consumed by the ceramic heating element will drop sharply after the temperature of the ceramic heating element exceeds its physical temperature. Therefore, the control unit determines that the slope value is negative based on the operating current measured by the current sensing unit and the operating current is less than the set threshold, and then controls the switch unit to stop providing the operating current to the ceramic The heating unit can avoid permanent damage to the ceramic heating device, and also control the alarm unit to issue a warning, so it can indeed achieve the purpose of the invention.

However, the above are only examples of the present invention. When the scope of implementation of the present invention cannot be limited by this, all simple equivalent changes and modifications made in accordance with the scope of the patent application of the present invention and the content of the patent specification still belong to Within the scope of the patent of the present invention.

1: control unit 2: Ceramic heating unit 3: Current sensing unit 4: Switch unit 5: Alarm unit 41: first end 42: second end 43: control terminal VIN: voltage source S1~S3: steps S30~S34: Sub-step

Other features and effects of the present invention will be clearly presented in the embodiments with reference to the drawings, in which: Figure 1 is a block diagram illustrating an embodiment of the ceramic heating device of the present invention; Figure 2 is a graph illustrating the correspondence between the operating current and temperature of a ceramic heating unit of the embodiment; and Fig. 3 is a flowchart illustrating the control method implemented in this embodiment.

1: control unit

2: Ceramic heating unit

3: Current sensing unit

4: Switch unit

41: first end

42: second end

43: control terminal

5: Alarm unit

VIN: voltage source

Claims (12)

A ceramic heating device suitable for a voltage source and contains: A ceramic heating unit electrically connected to the voltage source to receive an operating current to generate heat; A current sensing unit, electrically connected between the voltage source and the ceramic heating unit, to detect the magnitude of the operating current received by the ceramic heating unit, and then generate a corresponding output signal; A switch unit is electrically connected between the voltage source and the ceramic heating unit, and includes a first terminal electrically connected to the voltage source, a second terminal electrically connected to the ceramic heating unit, and a control signal receiving unit Control the terminal, and control the conduction or non-conduction between the first terminal and the second terminal according to the control signal; and A control unit electrically connects the current sensing unit and the switch unit, and generates the control signal so that the switch unit controls the conduction between the first terminal and the second terminal, and receives the current sensing unit Output signal to obtain the magnitude of the operating current. When the control unit determines that a slope value of the operating current changes with time is less than or equal to zero, and determines that the operating current is less than a set threshold, the control signal is generated to enable the switch The unit controls the non-conduction between the first terminal and the second terminal. The ceramic heating device according to claim 1, wherein the control unit calculates a change in the magnitude of the operating current in the predetermined time period according to the output signal every predetermined time period to obtain the slope value. The ceramic heating device according to claim 1, wherein the set threshold is equal to a maximum value of the operating current multiplied by a predetermined coefficient, and the predetermined coefficient is between 0 and 1. The ceramic heating device according to claim 3, wherein the control unit pre-stores the maximum value corresponding to the operating current of the ceramic heating unit, or the control unit obtains the operation according to the received output signal The maximum value of the current. The ceramic heating device according to claim 1, wherein, when the control unit determines that the operating current is less than a threshold after opening for a predetermined time after being turned on, the control signal is generated so that the switch unit controls the There is no conduction between the first terminal and the second terminal, and the threshold after startup is related to a maximum value of the operating current. The ceramic heating device according to claim 1, further comprising an alarm unit electrically connected to the control unit, when the control unit generates the control signal to make the switch unit control the first terminal and the second terminal to be non-conducting When the time, the alarm unit is controlled to send out an alarm notification, and the alarm notification includes at least one of a warning sound and a warning light. A control method is suitable for a ceramic heating device. The ceramic heating device includes a ceramic heating unit, a current sensing unit, a switch unit, and a control unit. The control method includes the following steps: (a) The control unit controls the switch unit to be turned on, so that the ceramic heating unit receives an operating current and generates heat; (b) Detect the magnitude of the operating current by the current sensing unit to generate a corresponding output signal; and (c) The control unit obtains the magnitude of the operating current according to the output signal, when the control unit determines that a slope value of the operating current changes with time is less than or equal to zero, and determines that the operating current is less than a set threshold , The switch unit is controlled to be non-conducting, so that the ceramic heating unit cannot receive the operating current. The control method according to claim 7, wherein, in step (c), the control unit calculates the change in the magnitude of the operating current in the predetermined time period according to the output signal every predetermined time period to obtain the slope value. The control method according to claim 7, wherein, in step (c), the set threshold is equal to a maximum value of the operating current multiplied by a predetermined coefficient, and the predetermined coefficient is between 0 and 1. The control method according to claim 9, wherein, in step (c), the control unit pre-stores the maximum value corresponding to the magnitude of the operating current of the ceramic heating unit, or the control unit according to the received Output the signal to obtain the maximum value of the operating current. The control method according to claim 7, wherein, in step (c), when the control unit determines that the operating current is less than a threshold after opening for a predetermined time after being turned on, the control signal is generated to The switch unit controls the non-conduction between the first terminal and the second terminal, and the threshold after startup is related to a maximum value of the operating current. According to the control method of claim 7, the ceramic heating device further includes an alarm unit, wherein, in step (c), when the control unit controls the switch unit to be non-conducting, the alarm unit is also controlled to send an alarm notification , The alarm notification includes at least one of a warning sound and a warning light.

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