Thermistor

Abstract

The utility model discloses a thermistor, which belongs to the technical field of resistors, and comprises a shell, a resistor body positioned in the shell, a conductive strip and a thermal expansion displacement mechanism, one end of the thermal expansion displacement mechanism is fixedly connected with the resistor body, the resistor body is connected with two pins extending out of the shell, at least one pin comprises two separated parts, and the two parts are connected with the conductive strip. The first conductive section is fixedly connected with the resistor body, and the second conductive section is fixedly connected with the shell; the conductive strip is simultaneously connected with the first conductive section and the second conductive section in a conductive state; the conductive strip is separated from the first conductive section or the second conductive section to be in a power-off state; the free end of the thermal expansion displacement mechanism is in linkage with the conductive strip and used for triggering the conductive strip to be switched from the conductive state to the power-off state. According to the utility model, the thermistor is protected in an over-temperature power-off mode, the structure is simple, the cost is low, and the control is more accurate.

Description

Technical Field

[0001] The utility model relates to the technical field of resistors, in particular to the technical field of resistor protection, and specifically is a thermistor. Background Art

[0002] Thermistors are heat / temperature sensitive components. According to the different temperature coefficients, they are divided into positive temperature coefficient thermistors (PTC) and negative temperature coefficient thermistors (NTC). The main feature of these two resistors is that their resistance value changes with temperature, and they are often used as sensor elements. However, thermistors generate heat during operation, especially when the resistance value increases, the heat generated will increase significantly, causing their own temperature to rise, which may damage the equipment or even cause a fire in severe cases. Therefore, it is necessary to improve the safety performance of thermistors.

[0003] At present, the main protection measure for thermistors is to implement over-current power-off, that is, to monitor the current of the thermistor and cut off the power when the current exceeds a certain value to prevent the thermistor from overheating. However, this method has some problems:

[0004] 1. An ammeter and an actuator are required to monitor the current and perform power-off operations, which increases the complexity of the overall structure and increases the cost.

[0005] 2. The overcurrent power-off method assumes that the current is positively correlated with the thermistor temperature, but in fact, the heat dissipation rate of the thermistor will be affected by the ambient temperature. Under the same current conditions, the temperature of the thermistor may be very different in cold winter and hot summer. Therefore, when the current reaches a certain value, the temperature of the thermistor does not necessarily reach its limit temperature, especially when the ambient temperature is low, which may cause the device to power off prematurely and affect the stable operation of the device. Utility Model Content

[0006] In order to solve the above problems, the utility model provides a thermistor, which protects the thermistor by over-temperature power-off.

[0007] The specific scheme of the utility model is as follows:

[0008] A thermistor, comprising:

[0009] case;

[0010] The resistor body is located in the shell, and the resistor body is connected to two pins extending outside the shell, wherein at least one pin includes two separate parts, namely a first conductive segment fixedly connected to the resistor body and a second conductive segment fixedly connected to the shell:

[0011] The conductive strip has two states: a conductive state in which the conductive strip is connected to both the first conductive segment and the second conductive segment; and a power-off state in which the conductive strip is separated from the first conductive segment or the second conductive segment.

[0012] A thermal expansion displacement mechanism with one end fixedly connected to the resistor body; a free end of the thermal expansion displacement mechanism is linked to the conductive strip to trigger the conductive strip to switch from a conductive state to a power-off state.

[0013] As a specific implementation of the utility model, the thermal expansion displacement mechanism is a bimetallic strip, which is formed by laminating two metals with different linear expansion coefficients.

[0014] As a specific implementation of the utility model, the free end of the thermal expansion displacement mechanism is connected to the conductive strip via a rope.

[0015] As a specific implementation of the utility model, the rope is an insulating rope.

[0016] As a specific implementation of the utility model, it also includes an elastic element for pushing the conductive strip to move so as to switch from the power-off state to the conductive state.

[0017] Compared with the existing technology, it has the following advantages:

[0018] The utility model sets the pin into two sections, and the two sections can be connected by a conductive strip, so that the on and off of the thermistor can be controlled by the conductive strip. At the same time, the utility model sets a thermal expansion displacement mechanism, which drives the conductive strip to move according to the temperature change of the resistor body, so as to control the on and off of the thermistor and realize the function of automatic power off. Compared with the existing method of controlling on and off by detecting current, the utility model has a simple structure and low cost, and can be controlled directly according to the temperature of the thermistor, so the control is more accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of a specific embodiment of the thermistor of the utility model in a conductive state;

[0020] Figure 2 for Figure 1 A schematic diagram of the embodiment shown in the power-off state;

[0021] In the figure, the housing 100; the resistor body 200; the conductive strip 300; the thermal expansion displacement mechanism 400; the elastic element 500;

[0022] Pin 210; Rope 410;

[0023] A first conductive segment 211 and a second conductive segment 212 . DETAILED DESCRIPTION

[0024] The present invention will be further described in detail below in conjunction with the embodiments and drawings, but the implementation manner of the present invention is not limited thereto.

[0025] Example

[0026] Please refer to Figure 1-2 , which shows the structure of a specific embodiment of the thermistor of the utility model, the thermistor of the utility model includes a housing 100, a resistor body 200, a conductive strip 300 and a thermal expansion displacement mechanism 400, wherein the resistor body 200 is located in the housing 100, the resistor body 200 is connected with two pins 210 extending outside the housing 100, and at least one pin 210 includes two separate parts, namely: a first conductive segment 211 fixedly connected to the resistor body 200, and a second conductive segment 212 fixedly connected to the housing 100; the conductive strip 300 is made of a conductive material, such as copper, iron, etc., and has two states, namely: the conductive strip 300 is simultaneously connected to the first conductive segment 211 and the second conductive segment 212 is ... The state in which the conductive segment 211 and the second conductive segment 212 are connected is called the conductive state, at which time the circuit of the thermistor is in a connected state; the state in which the conductive strip 300 is separated from the first conductive segment 211 or the second conductive segment 212 is called the power-off state, at which time the thermistor is in a circuit-breaking and power-off state; one end of the thermal expansion displacement mechanism 400 is fixedly connected to the resistor body 200, and the heat of the resistor body 200 is used to drive the free end of the thermal expansion displacement mechanism 400 to move, and the free end is linked with the conductive strip 300, so that the thermal expansion displacement mechanism 400 is used to trigger the movement of the conductive strip 300, so that when the temperature is high, the conductive strip 300 switches from the conductive state to the power-off state to protect the thermistor.

[0027] The thermal expansion displacement mechanism 400 mainly drives the free end to move by virtue of its own deformation after the temperature rises. In some embodiments, for example Figure 1 As shown, the thermal expansion displacement mechanism 400 is a bimetallic strip; the bimetallic strip is formed by stacking two metal strips with different linear expansion coefficients, which is often used in bimetallic thermometers. The specific structure and principle are not described in detail here. After the temperature changes, the two metals move their free ends due to the different expansion coefficients, such as Figure 1-2 As shown, the conductive strip 300 is driven to move. The thermal expansion displacement mechanism 400 and the conductive strip 300 can be connected by a flexible rope 410. By adjusting the length of the rope 410, the thermistor temperature of the conductive strip 300 when switching from the conductive state to the de-energized state can be adjusted.

[0028] Of course, in order to prevent the current from flowing along the rope 410, the bimetallic strip, and the resistor body 200, an insulating barrier is set on the path of the conductive strip 300, the rope 410, the thermal expansion displacement mechanism 400, and the resistor body 200. For example, the rope 410 is made of an insulating material, such as nylon rope. For another example, an insulating and heat-conductive ceramic block is set between the resistor body 200 and the thermal expansion displacement mechanism 400.

[0029] In addition, in order to facilitate the thermistor to continue to work normally after the temperature is reduced, in some embodiments, an elastic element 500, such as a spring, may be provided to push the conductive strip 300 to move so as to switch from the power-off state to the conductive state. In addition, an insulating barrier may be provided on the path of the conductive strip 300, the elastic element 500, and the shell 100 to prevent the current from being conducted to the shell 100. Of course, the shell 500 may also be made directly of insulating material, such as plastic.

[0030] The above is only a preferred specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the embodiments of the present invention should be covered within the protection scope of the present invention.

Claims

1. A thermistor, characterized in that: include: case; A resistor body located in the housing, the resistor body being connected to two pins extending outside the housing, wherein at least one of the pins comprises two separate parts, namely a first conductive segment fixedly connected to the resistor body and a second conductive segment fixedly connected to the housing; A conductive strip, wherein the conductive strip has two states: a conductive state in which the conductive strip is connected to both the first conductive segment and the second conductive segment; and a power-off state in which the conductive strip is separated from the first conductive segment or the second conductive segment; A thermal expansion displacement mechanism with one end fixedly connected to the resistor body, wherein the free end of the thermal expansion displacement mechanism is linked with the conductive strip to trigger the conductive strip to switch from a conductive state to a power-off state.

2. A thermistor according to claim 1, characterized in that: The thermal expansion displacement mechanism is a bimetallic strip, which is formed by laminating two metals with different linear expansion coefficients.

3. A thermistor according to claim 2, characterized in that: The free end of the thermal expansion displacement mechanism is connected to the conductive strip via a rope.

4. A thermistor according to claim 3, characterized in that: The rope is an insulating rope.

5. A thermistor according to claim 1, characterized in that: An elastic element is also included, which is used to push the conductive strip to move so as to switch from the power-off state to the power-on state.

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