Planar temperature sensor and application circuit

Abstract

The invention relates to a temperature sensor in the field of industrial automation, and discloses a planar temperature sensor and an application circuit. According to the invention, on the premise of a new carbon-based nest material; according to the characteristics of the novel carbon-based nest material, the invention provides the electric heating electronic control equipment which can exert the characteristics of the novel carbon-based nest material. The device can detect the average temperature of a plane or a special-shaped surface in the heating process of a plane body or a special-shaped body, and the average temperature of the plane body or the special-shaped surface is increased when the plane body or the special-shaped surface is covered by an object with a small heat conductivity coefficient, or the average temperature of the plane body or the special-shaped surface is reduced when the plane body or the special-shaped surface is locally contacted with an object with a large heat conductivity coefficient. And the application circuit is used for detecting and alarming the generated temperature change. And meanwhile, automatic temperature control with higher precision than that of a point temperature sensor can be realized. The method is suitable for controlling various types of electric heating or refrigerating equipment d.

Description

Technical Field

[0001] The present invention relates to a temperature sensor in the field of industrial automation: a carbon-based nest new material planar temperature sensor and an application circuit designed for the special functions of the carbon-based nest new material in various industrial automation fields. Background Art

[0002] At present, the common types of temperature sensors include bimetallic temperature sensors, semiconductor temperature sensors, PTC temperature sensors, elastic metal sheet fixed-point temperature sensors, etc. All of the above sensors are point temperature sensors, that is, they detect the temperature of a certain point in space or an object. When measuring uneven heating surfaces, multiple point temperature sensors need to be configured. The sampling transmission line and sampling circuit of the sensor are relatively complex, especially in some products with low cost performance (such as simple electric heating devices).

[0003] Materials such as carbon fiber, graphene, and carbon nanotubes that have high efficiency in converting electrical energy into thermal energy have begun to enter the market. Carbon fiber and graphene electric heating use non-metallic carbon materials and are sealed with high-strength insulating materials under high temperature and high pressure to form a heating element. When the power is turned on and the heating element is heated, the electric heating device directly converts electrical energy into thermal energy. However, there are also some disadvantages; such as 1. Electric heating elements made of carbon fiber, graphene and other materials require temperature sensors to control the temperature change of the heating element when realizing temperature control. The temperature control method is point temperature control (the temperature of the sensor test point). When other parts of the heating element that do not have temperature sensors are partially or completely covered by cotton or other items, the temperature of the covered surface will gradually increase and cause a fire. 2. Carbon fiber and graphene electric heating materials are mainly printed on thermally conductive insulating carriers in the form of ink. During the printing process, the printing surface will be uneven, resulting in uneven heating surfaces. The temperature difference between the higher temperature position and the lower temperature position will gradually increase with the use time, resulting in damage to the heating element. 3. When some resistance wires or other forms of heating methods act on objects with poor thermal conductivity, uneven heating of the heating surface will also occur. Summary of the invention

[0004] In view of the shortcomings of point temperature sensors, the present invention provides a planar temperature sensor and application circuit that can give full play to the characteristics of the new carbon-based nest material. In particular, it is an application circuit that can detect the average temperature of a plane or a special-shaped surface during the heating process of a plane or a special-shaped body, and detect and alarm the temperature changes caused by the average temperature increase when the plane or special-shaped body is partially covered by an object with a small thermal conductivity, or the average temperature decreases when the plane or special-shaped body is partially in contact with an object with a large thermal conductivity. At the same time, automatic temperature control with higher accuracy than point temperature sensors can be achieved.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: including:

[0006] The plane or profiled surface temperature sensor is used to detect the temperature of a plane or profiled surface object or space. The plane or profiled surface temperature sensor is made of carbon-based nest new materials into conductive ink and smeared or printed on different types of insulating material carriers to form a curve or a straight line and add electrodes at both ends. The plane or profiled surface temperature sensor is attached to the object to be measured. As the temperature of the plane or profiled surface sensor increases, its resistance increases or the voltage increases.

[0007] The flat or profiled surface temperature sensor application circuit is used to process the resistance or voltage signal of the sensor and synchronously detect the temperature of multiple flat or profiled surface temperature sensors. In the flat or profiled surface temperature sensor application circuit, all electronic components are installed on a circuit board. The circuit board is installed in a controller box, and the switch in the controller box controls the heating or cooling device controller to achieve the purpose of safety protection.

[0008] The present invention provides a planar temperature sensor and an application circuit. It has the following beneficial effects:

[0009] 1. Good safety performance. Flat or special-shaped surface temperature sensors and application circuits are safe to use for heating bodies. For example, electric heating plates made of carbon fiber or graphene are attached with flat or special-shaped surface temperature sensors. After the sensor change signal is processed by the application circuit, when the local heating body is covered, the average temperature of the sensor rises and exceeds the set safety temperature, the application circuit alarms or cuts off the power supply. In this way, the temperature of the heating body is limited to a safe range to avoid fire.

[0010] 2. Higher temperature control accuracy: Since the average temperature of the entire surface of the object is detected, it has higher accuracy than point detection, so it is suitable for situations where the overall surface automatic temperature control requires high accuracy. For example, the application of thyristor control in the application circuit can stabilize the heating element temperature (set temperature) within the range of plus or minus 0.5 degrees. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Method for making a planar temperature sensor

[0012] Figure 2 Planar temperature sensor for over-temperature protection and circuit

[0013] Figure 3 For specific implementation

[0014] The object of the present invention is accomplished in the following manner: Figure 1 , 2 The invention provides a detailed description of the manufacturing and application circuit working principle of a planar temperature sensor: Figure 1 , 2 .

[0015] See attached Figure 1 , a method for making a planar temperature sensor; a planar curved temperature sensor (1) and a planar linear temperature sensor (8). The making method is to apply or print ink (2, 4, 7) made of a carbon-based nest new material on the plane of a flat or profiled insulating material (5), the ink forms a curved surface (2) or a straight surface (7) on the insulating material, and electrodes (3, 10) are added at both ends of the curved surface or electrodes (6, 9) are added at both ends of the straight surface to form a conductor with a certain resistance. The resistance changes with the change of temperature, and the voltage at both ends of the resistance also changes with the change of temperature. The size of the planar temperature sensor can be made in the range of 3000 square centimeters to 100 square centimeters, and the thickness ranges from 0.03 mm to 2 mm.

[0016] Planar sensor application circuit; see attached Figure 2 Planar temperature sensor is used for over-temperature protection and circuit. Figure 1The manufactured sensor (17) is adhered to the surface of the object (18) whose temperature is to be detected. One end of the electrodes at both ends of the sensor is connected to the common ground line, and the other ends are connected to a comparison circuit composed of U2 (12) (U2 is TL431 or a component with comparator characteristics), a resistor (R5), and a capacitor C2. The anode of U2 (12) is connected to the common ground, and one end of the cathode is connected to the positive pole of the power supply 5-24V through the resistor R3. The other end is connected to a comparison input end of the comparator U1 (19) through a filter circuit composed of L1, R4, and C1. The other input end is connected to the positive pole of the power supply through resistors R1 and R2, R1 is connected to the common ground, and R2 is connected to the common ground, forming a comparison reference voltage. The output end of the comparator U1 (19) is connected to the heating or cooling control device (13) through the signal processing circuit (11). The reference terminal of comparator U2 (12) is connected to resistor R5 and capacitor C2. The other end of C2 is grounded. The other end of R5 is connected to a 5-24V power supply. R5 and the sensor form a voltage divider. The size of R5 is determined by the reference voltage of U2 (12). For example, if the reference voltage is 2.5V, the over-temperature protection needs to be lower than 2.5V, and the under-temperature protection needs to be higher than 2.5V. The working principle of a single planar temperature sensor 1 is: when the temperature of the detected object rises or falls, the resistance or voltage of the planar temperature sensor changes, and the voltage divided by R3 changes. For example, at a certain temperature, the voltage divided by R3 is 2.3V, and the cathode of U2 (12) is the power supply voltage. When the temperature rises to the protection temperature due to covering or other reasons, the voltage divided by R3 is 2.5V. The cathode voltage of U2 (12) drops from the power supply voltage to 2.5V. After filtering by L1, C1, and R4, the input voltage at one end of the comparator U1 (19) drops from the original power supply voltage to 2.5V. If the voltage set by R1 and R2 is higher than 2.5V, the output voltage of the comparator UI (19) is reversed, and the signal is converted into a switch signal adapted to the actual requirements through the signal processing circuit (11), thereby controlling the switch of the heating power supply of the heating device. The cooling control principle is basically the same, except that the voltage divided by R3 is set opposite to that of the cooling device. The principle is not described here.

[0017] In the case where multiple planar temperature sensors are required, three buses (14) (dashed line part) are used to connect 1-n (15, 16) sensors. The circuit parts of sensors 2 to n (15, 16) are respectively U3-Un, R6-Rn, C3-Cn, and the components and connection methods used in the planar temperature sensor 1 are the same. Its working principle is: since each sensor circuit is the same, as mentioned above, the reference voltage of U1-Un is all around 2.3V, and the cathode voltage is close to the power supply voltage. If one of the sensors is covered by an object with a low thermal conductivity or other reasons, the average temperature of the heating element rises to the protection temperature, that is, 2.5V. Since the cathode voltage supplied to U1-UN through R3 is common, the decrease in the cathode voltage of any U1-Un comparator will cause its common voltage to drop to 2.5V. The working process of a single sensor as mentioned above is completed. Thereby achieving the purpose of safety protection.

[0018] For specific implementation, refer to the attached Figure 3

[0019] Figure 1 The flat sensor (2) shown is attached to the heating or cooling device (1). The heating or cooling device can be a special-shaped plane, such as a triangular plane, a circular plane, etc. The sensor can also be made into a special shape. The two lines output by the 1, 2-n (2, 9, 11) sensors are connected to the converter (3, 8, 10). The converter (3) is the converter of the No. 1 sensor. U2, R5, C2 are installed on the circuit board. After installation, they are encapsulated with epoxy resin or installed in a small box. The converters of the No. 2 sensor to the n sensors are installed respectively U3, R6, C3 to Un, Rn, Cn according to the installation method of the No. 1 converter (3). The converters (3, 8, 10) are connected together through three buses (4). The three buses (4) enter the control box (5), and the U1 (19) and the peripheral circuits R1, R2, R3, R4, C1, L1 and the actual required signal processing circuit are installed on the circuit board in the control box (5). Through the switch quantity, the switch (7) controls the heating or cooling device power output by the heating or cooling device controller (6) or controls the controllable circuit of the heating or cooling device controller (6). Thus, the purpose of safety protection is achieved. The temperature detection circuit that needs digital display is the same as the point temperature sensor circuit, and the present invention will not describe it.

[0020] The present invention provides a planar temperature sensor and application circuit. Since the planar temperature sensor takes the average temperature of the surface, it is practical for heating or cooling flat or special-shaped surfaces with uneven temperature, such as graphene and carbon fiber electric heating plates. Due to the commonly used printing and other methods of conductive heating coatings, uneven heating surface temperature is prone to occur. The use of a planar temperature sensor can effectively prevent the expansion of the uneven heating temperature gap, the occurrence of burning plates, and avoid fires when parts are covered. In terms of refrigeration, such as refrigerators or freezers, it can prevent uneven phenomena such as overcooling of the parts where objects are placed, which leads to damage and reduced service life.

Claims

1. A planar temperature sensor and an application circuit, characterized in that: include: A planar curved temperature sensor (1) and a planar linear temperature sensor (8). The manufacturing method is to apply or print ink (2, 4, 7) made of carbon-based nest new materials on the plane of a flat or special-shaped insulating material (5), and the ink forms a curved surface (2) or a straight surface (7) on the insulating material, and electrodes (3, 10) are added at both ends of the curved surface or electrodes (6, 9) are added at both ends of the straight surface to form a conductor with a certain resistance. The resistance changes with the change of temperature, and the voltage at both ends of the resistance also changes with the change of temperature. The size of the planar temperature sensor can be made into a range of 3000 square centimeters to 100 square centimeters, and a thickness of 0.03 mm to 2 mm. The sensor (17) is attached to the surface of the object (18) whose temperature is to be detected. One end of the electrodes at both ends of the sensor is connected to a common ground line, and the other ends are connected to a comparison circuit composed of U2 (12) (U2 is TL431 or a component with comparator characteristics), a resistor (R5), and a capacitor C2. The anode of U2 (12) is connected to the common ground, and one end of the cathode is connected to the positive pole of the power supply 5-24V through a resistor R3. The other end is connected to a comparison input end of the comparator U1 (19) through a filter circuit composed of L1, R4, and C1. The other input end is connected to the positive pole of the power supply through resistors R1 and R2, R1 is connected to the positive pole of the power supply, and R2 is connected to the common ground, forming a comparison reference voltage. The output end of the comparator U1 (19) is connected to the heating or cooling control device (13) through a signal processing circuit (11). The reference terminal of comparator U2 (12) is connected to resistor R5 and capacitor C2, the other end of C2 is grounded, the other end of R5 is connected to a 5-24V power supply, R5 and the sensor form a voltage divider, and the size of R5 is determined by the reference voltage of U2 (12).

2. A planar temperature sensor and application circuit according to claim 1, characterized in that: When multiple planar temperature sensors are needed, three buses (14) (dashed line part) are used to connect 1-n (15, 16) sensors. The circuit parts of sensors 2 to n (15, 16) are respectively U3-Un, R6-Rn, C3-Cn, and the components and connection methods used in planar temperature sensor 1 are the same.

3. A planar temperature sensor and application circuit according to claim 1, characterized in that: The heating or cooling equipment can be a special-shaped plane, such as a triangle, a circle, etc. The sensor can also be made into a special shape.

4. A planar temperature sensor and application circuit according to claim 1, characterized in that: The first sensor of the converter (3) is installed with U2, R5, C2 on the circuit board, and the second sensors U3, R6, C3 to Un, Rn, Cn are installed according to the installation method of the first converter (8, 10). The converters (3, 8, 10) are connected together through three buses (4). The three buses (4) enter the control box (5).

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