Thermal protector and pressure detection device and detection method for movable contact spring of thermal protector

Abstract

The invention relates to a thermal protector and a pressure detection device and method for a movable contact spring of the thermal protector, and belongs to the field of thermal protectors. The double-metal-sheet heater comprises a plug pin, a cover plate, a movable contact spring, a double-metal-sheet, a first static pin, a second static pin, a heating body, a third static pin and a base, the two ends of the heating body are welded to the first static pin and the second static pin respectively, one end of the movable contact spring is electrically connected with the first static pin, and the other end of the movable contact spring is matched with one end of the third static pin. One end of the movable contact spring is connected with the first static pin, the other end of the third static pin is electrically connected with the plug pin, and when the other end of the movable contact spring is in contact with one end of the third static pin, the second static pin, the heating body, the first static pin, the movable contact spring, the third static pin and the plug pin are sequentially connected to form an electric loop. A protruding point is arranged in the center of the movable contact spring, a static contact is welded to one end of the third static pin, and the gasket is electrically connected with the first static pin.

Description

Technical Field

[0001] The invention relates to a thermal protector and a pressure detection device and a detection method for a movable reed thereof, belongs to the field of thermal protectors, and is mainly used for over-temperature rise and over-current protection of refrigeration compressors or other motors. Background Art

[0002] Currently, all refrigeration compressors are equipped with a thermal protector, which is primarily used to protect the compressor from overheating and overcurrent. Conventional thermal protectors consist of a plug, a fixed pin assembly, a dynamic reed assembly, and a heating element assembly, forming a protective circuit that is electrically connected under normal conditions and disconnected under abnormal conditions. The thermal protector is equipped with a heating element and a bimetallic strip. When the refrigerator compressor stalls or experiences voltage instability, the current increases. When the heat generated by the heating element reaches the bimetallic strip's set operating temperature, the thermal protector activates and disconnects the electrical circuit. When the thermal protector reaches the set recovery temperature, the bimetallic strip resets, reconnecting the circuit.

[0003] In addition to the physical, chemical and bending properties, the dynamic spring in the thermal protector also has mechanical properties. After thousands of mechanical up and down movements, not only the physical, chemical and bending properties change, but also the yield strength, that is, the elastic force, gradually decreases. When a material that meets the elastic force requirements is required, the calculation formula can be used. Calculate (where F represents the bending force N, K represents the bending stiffness coefficient N / m, and δ represents the stretching amount m).

[0004] In the thermal protector of the prior art, the material used for the movable spring is usually nickel-copper alloy or beryllium-copper alloy. Due to the characteristics of physical, chemical, and bending properties, the movable spring generates heat through large current and changes after thousands or tens of thousands of opening and closing cycles.

[0005] by Figure 5 As shown, the gap a between the protrusion of the moving reed and the bimetallic strip gradually increases with the change of physical and bending properties. At this time, the curvature formed by the moving reed changes accordingly, and the yield strength of the moving reed, that is, the pressure decay, decreases, resulting in an increase in the contact resistance and heat generation between the moving contact and the static contact, which affects the service life of the contacts. When the distance of the gap a is greater than the upper limit, the thermal protector will be out of sync when it is actuated, that is, flashover occurs and it cannot be used. In severe cases, it may cause the refrigeration compressor to burn out. The moving reed is made of nickel-copper alloy or beryllium-copper alloy with low resistance and good conductivity. It is easy to cause cold welding or insufficient strength when welding the moving contact and the gasket.

[0006] When a is greater than 0.3mm, the spring force is less than 0.15N, and the gap between the moving and static contacts is too small after the bimetallic strip heats up and suddenly jumps, the contacts close and conduct before the bimetallic strip cools down and resets. This phenomenon is called reset asynchrony. When a is less than 0.12mm, the spring force is greater than 0.4N, and the moving and static contacts separate and open before the bimetallic strip heats up and suddenly jumps, this phenomenon is called action asynchrony. Therefore, the control of the gap a and the bending spring force F is extremely important. Therefore, it is necessary to use a formula to accurately control the bending spring force required by the moving spring.

[0007] Currently, when testing the pressure of the dynamic reed, manual testing is performed using a dynamometer, which results in large test errors, inaccurate judgments, and low testing efficiency. Summary of the Invention

[0008] The object of the present invention is to overcome the above-mentioned deficiencies in the prior art and to provide a thermal protector with a rational structural design and a pressure detection device and method for its movable spring.

[0009] The technical solution adopted by the present invention to solve the above problems is: the thermal protector includes a pin, a cover plate, a movable spring, a bimetallic strip, a static pin 1, a static pin 2, a heating element, a static pin 3 and a base, the two ends of the heating element are respectively welded to the static pin 1 and the static pin 2, one end of the movable spring is electrically connected to the static pin 1, the other end of the movable spring cooperates with one end of the static pin 3, and the other end of the static pin 3 is electrically connected to the pin, when the other end of the movable spring contacts one end of the static pin 3, the static pin 2, the heating element, the static pin 1, the movable spring, the static pin 3 and the pin are connected in sequence to form an electrical circuit, and its structural characteristics are: a pad is welded to one end of the movable spring, a moving contact is welded to the other end of the movable spring, a convex point is provided at the center of the movable spring, and the static pin A static contact is welded to one end of the third leg, the pad is electrically connected to the static leg, and when the dynamic contact contacts the static contact, the dynamic reed is arranged in an arc-shaped structure. At this time, a certain gap a is maintained between the protrusion and the bimetallic strip, 0.3mm≥a≥0.12mm, preferably a=0.15mm. The value of the force generated by the variable when the dynamic reed forms the arc-shaped structure is the test value of the bending elastic force F, and the value range of F is 0.15N-0.4N. The dynamic reed is made of a multi-layer composite material of copper alloy and stainless steel, that is, a composite method of copper layer + stainless steel layer, copper layer + stainless steel layer + copper layer, stainless steel layer + copper layer + stainless steel layer, or copper alloy layer + stainless steel layer, copper alloy layer + stainless steel layer + copper alloy layer, stainless steel layer + copper alloy layer + stainless steel layer, etc.

[0010] The calculation process of the bending force F is as follows: (Formula 1) Where K represents the bending stiffness coefficient, δ represents the stretching amount, (Formula 2) Where E represents the elastic modulus, b represents the width of the dynamic reed, h represents the thickness of the dynamic reed, and L represents the length of the dynamic reed.

[0011] Furthermore, the pins are arranged on the cover plate, and the movable spring, bimetallic strip, static pin 1, static pin 2, heating element and static pin 3 are all arranged in a cavity formed by the cover plate and the base.

[0012] Furthermore, the heating element, bimetallic strip and movable spring are arranged in sequence from bottom to top.

[0013] Furthermore, bent reinforcement edges and positioning ears are provided on both sides of the movable spring.

[0014] Furthermore, another technical purpose of the present invention is to provide a pressure detection device for a movable spring.

[0015] The above technical objectives of the present invention are achieved through the following technical solutions.

[0016] A pressure detection device for a movable spring is used to detect the pressure of the movable spring in a thermal protector. Its structural characteristics are: the pressure detection device for the movable spring includes a placement mechanism, a pressing mechanism and a testing mechanism, the placement mechanism is located below the pressing mechanism and the testing mechanism, and the pressing mechanism and the testing mechanism both cooperate with the placement mechanism.

[0017] Furthermore, the placement mechanism includes a placement seat and cylinder one, the placement seat is connected to the piston rod of cylinder one, and sensor No. 1 and sensor No. 2 are installed on the cylinder barrel of cylinder one.

[0018] Furthermore, the pressing mechanism includes a pressing plate and cylinder 2, the pressing plate is connected to the piston rod of cylinder 2, and sensor No. 3 and sensor No. 4 are installed on the cylinder barrel of cylinder 2.

[0019] Furthermore, the testing mechanism includes a connecting rod, cylinder three, a force sensor, cylinder four and a pull rod, the connecting rod is connected to the cylinder barrel of cylinder three, the piston rod of cylinder three is connected to the cylinder barrel of cylinder four, the piston rod of cylinder four is connected to the force sensor, the force sensor is connected to the pull rod, a slot is provided on the pull rod, the cylinder barrel of cylinder three is installed with sensor No. 5 and sensor No. 6, and the cylinder barrel of cylinder four is installed with sensor No. 7 and sensor No. 8.

[0020] Furthermore, the pressure detection device of the dynamic spring is controlled by a control system, which includes a programmable controller and a force measurement and control transmitter. The programmable controller includes a central processing unit, an analog-to-digital converter, an input interface and an output interface. The force measurement and control transmitter is connected to the analog-to-digital converter, and the analog-to-digital converter, input interface and output interface are all connected to the central processing unit.

[0021] Furthermore, the positive input terminal and negative input terminal of the force sensor are respectively connected to the positive excitation voltage terminal and negative terminal of the force measurement and control transmitter, the positive output terminal and negative output terminal of the force sensor are respectively connected to the positive signal voltage terminal and negative terminal of the force measurement and control transmitter, the positive analog signal output terminal and negative analog signal output terminal of the force measurement and control transmitter are respectively connected to the positive terminal and negative terminal of the analog-to-digital converter, and the digital signal converted by the analog-to-digital converter is input to the central processing unit; The X0 end of the input interface is connected to the static pin 3 of the thermal protector under test, the static pin 2 of the thermal protector under test is connected to the negative end of the DC power supply, the X1-X8 ends of the input interface are respectively connected to one end of sensor No. 1, sensor No. 2, sensor No. 3, sensor No. 4, sensor No. 5, sensor No. 6, sensor No. 7, and sensor No. 8, the other ends of sensor No. 1, sensor No. 2, sensor No. 3, sensor No. 4, sensor No. 5, sensor No. 6, sensor No. 7, and sensor No. 8 are all connected to the negative end of the DC power supply, the common end com of the input interface is connected to the positive end of the DC power supply, and the input signal is transmitted to the central processing unit through the input interface; The Y0-Y3 ends of the output interface are respectively connected to one end of solenoid valve 1, solenoid valve 2, solenoid valve 3, and solenoid valve 4, and the other ends of solenoid valve 1, solenoid valve 2, solenoid valve 3, and solenoid valve 4 are all connected to the positive end of the DC power supply. The negative end of the output interface is connected to the negative end of the DC power supply. The solenoid valve 1, solenoid valve 2, solenoid valve 3, and solenoid valve 4 are respectively connected to cylinder 1, cylinder 2, cylinder 3, and cylinder 4 through air pipes. The output signal of the central processing unit controls each solenoid valve to switch the air path through the output interface, and the switched air path controls each cylinder to perform corresponding actions.

[0022] Furthermore, another technical purpose of the present invention is to provide a detection method for a pressure detection device of a movable spring.

[0023] The above technical objectives of the present invention are achieved through the following technical solutions.

[0024] A detection method for a pressure detection device for a movable spring, characterized in that: the detection method is as follows: S1. Set the range parameters of the dynamic spring force test of the thermal protector, and set the lower limit value F1 = 0.15N and the upper limit value F2 = 0.4N respectively; S2. Place the thermal protector under test on the placement seat. After the test starts, the central processing unit automatically runs the test process according to the program design requirements. First, the input interface is used to detect whether each test action is in the original position. The original position signal of cylinder one, that is, sensor No. 1, has a connection signal. The original position signal of cylinder two, that is, sensor No. 3, has a connection signal. The original position signal of cylinder three, that is, sensor No. 5, has a connection signal. The original position signal of cylinder four, that is, sensor No. 7, has a connection signal. The X0 end of the input interface should have a connection signal, which means that the thermal protector under test should be in the closed state. If all positions are in the original position, the next action is executed. S3, the output interface is connected to the Y0 terminal control signal, the solenoid valve is energized, the air circuit controls the cylinder to send the thermal protector to the specified test position, and the X2 terminal of the input interface receives the delivery position signal from the second sensor and then performs the next action control; S4, the output interface is connected to the Y1 terminal control signal, the solenoid valve 2 is energized, the air circuit controls the cylinder 2 to push the pressing plate to the specified position above the placement seat, and the X4 terminal of the input interface receives the pressing in place signal from the No. 4 sensor and then performs the next action control; S5, the output interface is connected to the control signal at the Y3 end, solenoid valve 4 is energized, and the air circuit controls cylinder 4 with the power sensor and the pull rod to descend to the side of the moving contact. The input interface X8 receives the descending position signal from the No. 8 sensor and then performs the next action control. S6, the output interface is connected to the control signal of the Y2 terminal, the solenoid valve 3 is energized, the air circuit controls the cylinder 3 to drive the cylinder 4, the force sensor and the pull rod to move the card slot to the inner side of the moving contact, and the X6 terminal of the input interface receives the moving position signal from the sensor 6 and then performs the next action control; S7, the output interface cuts off the control signal from the Y3 terminal, the solenoid valve 4 loses power, and the air circuit control cylinder 4 with the power sensor and the pull rod slowly rises. At this time, the force sensor is subjected to force to generate a force sampling electrical signal. This signal is converted and amplified by the force measurement and control transmitter to generate an analog signal proportional to the pressure of the dynamic spring. It is then converted into a digital signal by the analog-to-digital converter and transmitted to the central processing unit for calculation and processing; when the dynamic contact is separated from the static contact, the X0 terminal of the input interface receives the contact disconnection signal. At this time, the data obtained by the central processing unit after calculation and processing is the bending elastic force F of the dynamic spring, and is saved at the same time. After the X7 terminal of the input interface receives the rising position signal from the seventh sensor, the next action control is carried out; S8, the output interface is connected to the Y3 end control signal, the solenoid valve four is energized, and the air circuit control cylinder four with the power sensor and the pull rod descends; the output interface cuts off the Y2 end control signal, the solenoid valve three loses power, the air circuit control cylinder three drives the cylinder four, the force sensor and the pull rod to move the slot to the outside of the moving contact; the output interface cuts off the Y3 end control signal, the solenoid valve four loses power, and the air circuit control cylinder four with the power sensor and the pull rod rises; the output interface cuts off the Y1 end control signal, the solenoid valve two loses power, and the air circuit control cylinder two drives the pressing plate to rise; the output interface cuts off the Y0 end control signal, the solenoid valve one loses power, and the air circuit control cylinder one drives the placement seat to retract. At this time, all test actions have returned to their original positions. After the input interface receives the original position signals from sensor No. 7, sensor No. 5, sensor No. 3, and sensor No. 1, the test cycle of a product ends; S9. The central processing unit compares the stored bending elastic force F with the set lower limit value F1 and upper limit value F2 for determination. If F1 < F < F2, the thermal protector under test is qualified; if F < F1 or F > F2, the thermal protector under test is defective.

[0025] Compared with the existing technology, the present invention has the following advantages: the movable spring in the thermal protector is made of a double-layer or multi-layer composite of copper (or copper alloy) and stainless steel. The physical, chemical, and bending properties of the stainless steel and copper alloy materials are combined to enhance the welding strength of the movable contact and the pad, and enhance the yield strength of the movable spring. The heat generated by large current and after thousands or tens of thousands of opening and closing cycles can reduce the curvature change of the movable spring.

[0026] In other words, the thermal protector's dynamic spring combines the physical, chemical, and bending properties of stainless steel and copper (or copper alloy) materials, thereby achieving excellent welding effects and rigidity requirements, thereby increasing product life. By replacing manual inspection with a pressure detection device, production efficiency and accuracy are greatly improved, problems caused by manual operating errors are avoided, and labor costs are reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the three-dimensional structure of the thermal protector according to an embodiment of the present invention.

[0028] Figure 2 Schematic diagram of the internal structure of the thermal protector according to an embodiment of the present invention.

[0029] Figure 3 Schematic diagram of the explosion structure of the thermal protector according to an embodiment of the present invention.

[0030] Figure 4 It is a schematic diagram of the three-dimensional structure of the movable spring according to an embodiment of the present invention.

[0031] Figure 5Schematic diagram of the cross-sectional structure of the thermal protector according to an embodiment of the present invention.

[0032] Figure 6 It is a schematic diagram of the three-dimensional structure of the pressure detection device according to an embodiment of the present invention.

[0033] Figure 7 It is a schematic diagram of the three-dimensional structure of the placement mechanism of an embodiment of the present invention.

[0034] Figure 8 It is a schematic diagram of the three-dimensional structure of the pressing mechanism of an embodiment of the present invention.

[0035] Figure 9 It is a schematic diagram of the three-dimensional structure of the testing mechanism according to an embodiment of the present invention.

[0036] Figure 10 4 is a circuit diagram of a control system according to an embodiment of the present invention.

[0037] In the figure: pin 1, cover 2, dynamic spring 3, bimetallic strip 4, static pin 1 5, static pin 2 6, heating element 7, static pin 3 8, base 9, Gasket 3-1, moving contact 3-2, bump 3-3, reinforcement edge 3-4, positioning ear 3-5, Static contact 8-1, Placement mechanism A, pressing mechanism B, testing mechanism C, Placement seat A1, cylinder A2, Pressing plate B1, cylinder 2 B2, Connecting rod C1, cylinder three C2, force sensor C3, cylinder four C4, pull rod C5, Card slot C5-1, Sensor No. 1 SQ1, Sensor No. 2 SQ2, Sensor No. 3 SQ3, Sensor No. 4 SQ4, Sensor No. 5 SQ5, Sensor No. 6 SQ6, Sensor No. 7 SQ7, Sensor No. 8 SQ8, Programmable controller PLC, force measurement and control transmitter CK, Central processing unit CPU, analog-to-digital converter AD, input interface IN, output interface OUT, Solenoid valve one FA2, solenoid valve two FB2, solenoid valve three FC2, solenoid valve four FC4. DETAILED DESCRIPTION

[0038] The present invention will be further described in detail below with reference to the accompanying drawings and through examples. The following examples are intended to explain the present invention but the present invention is not limited to the following examples.

[0039] Example.

[0040] See also Figures 1 to 10As shown, it should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention. Therefore, they have no substantial technical significance. Any modification of the structure, change in the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the efficacy and purpose that can be achieved by the present invention. At the same time, if there are references to terms such as "upper", "lower", "left", "right", "middle" and "one" in this specification, they are only for the convenience of description and are not used to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0041] The thermal protector in this embodiment (such as Figure 1-Figure 5 As shown), it includes a pin 1, a cover plate 2, a movable reed 3, a bimetallic strip 4, a static pin 1 5, a static pin 2 6, a heating element 7, a static pin 3 8 and a base 9. The pin 1 is arranged on the cover plate 2, and the movable reed 3, the bimetallic strip 4, the static pin 1 5, the static pin 2 6, the heating element 7, and the static pin 3 8 are all arranged in a cavity formed by the cover plate 2 and the base 9. The heating element 7, the bimetallic strip 4 and the movable reed 3 are arranged in sequence from bottom to top.

[0042] The two ends of the heating element 7 in this embodiment are respectively welded to the static pin 1 5 and the static pin 2 6, one end of the movable spring 3 is electrically connected to the static pin 1 5, the other end of the movable spring 3 cooperates with one end of the static pin 3 8, and the other end of the static pin 3 8 is electrically connected to the pin 1. When the other end of the movable spring 3 contacts one end of the static pin 3 8, the static pin 2 6, the heating element 7, the static pin 1 5, the movable spring 3, the static pin 3 8, and the pin 1 are connected in sequence to form an electrical circuit.

[0043] In this embodiment, the movable spring 3 is provided with a bent reinforcement edge 3-4 and a positioning ear 3-5 on both sides. A pad 3-1 is welded to one end of the movable spring 3, and a movable contact 3-2 is welded to the other end of the movable spring 3. A convex point 3-3 is provided at the center of the movable spring 3, and a static contact 8-1 is welded to one end of the static foot 8. The pad 3-1 is electrically connected to the static foot 5, and when the movable contact 3-2 contacts the static contact 8-1, the movable spring 3 is arranged in an arc shape. At this time, a certain gap a is maintained between the convex point 3-3 and the bimetallic strip 4, 0.3 mm≥a≥0.12mm, preferably a=0.15mm, the value of the force generated by the variable when the dynamic spring piece 3 forms an arc-shaped structure is the test value of the bending elastic force F, and the value range of F is 0.15N-0.4N. The dynamic spring piece 3 is made of a multi-layer composite material of copper alloy and stainless steel, that is, copper layer + stainless steel layer, copper layer + stainless steel layer + copper layer, stainless steel layer + copper layer + stainless steel layer or copper alloy layer + stainless steel layer, copper alloy layer + stainless steel layer + copper alloy layer, stainless steel layer + copper alloy layer + stainless steel layer and other composite methods.

[0044] The calculation process of the bending force F is as follows: (Formula 1) Where K represents the bending stiffness coefficient N / m, δ represents the stretching amount m, 0.0003m≥δ≥0.00012m, (Formula 2) Where E represents the elastic modulus GPa, b represents the width of the dynamic reed m, h represents the thickness of the dynamic reed m, and L represents the length of the dynamic reed m.

[0045] That is to say, K can be obtained by substituting the known quantities E, b, h, and L into Formula 2, and then F can be obtained by substituting the known quantities δ and K obtained from Formula 2 into Formula 1.

[0046] Example 1: When the dynamic spring 3 is made of nickel-copper alloy, where E=130GPa, b=0.006m, h=0.00015m, L=0.022m, δ=0.0003 m, and a=0.12mm, the dynamic spring 3 undergoes maximum deformation, and the gap a is minimum. F = 0.298N (in line with the F value range of 0.15N-0.4N) Example 2: When the dynamic spring 3 is made of stainless steel alloy, where E=200GPa, b=0.006m, h=0.00015m, L=0.022m, δ=0.0003m, and a=0.12mm, the dynamic spring 3 undergoes maximum deformation, and the gap a is minimum. F = 0.458N (does not conform to the F value range of 0.15N-0.4N) Example 3: When the dynamic spring 3 is made of a composite material of stainless steel alloy and copper alloy, where E=170GPa, b=0.006m, h=0.00015m, L=0.022m, δ=0.0003 m, and a=0.12mm, the dynamic spring 3 undergoes maximum deformation, and the gap a is minimum. F = 0.389N (in line with the F value range of 0.15N-0.4N) In the above example, after thousands of up and down mechanical movements, the stretch δ decreases, thereby reducing the bending force F. When the stretch δ decreases to 0.00012 m (i.e., the dynamic reed 3 undergoes minimum deformation, at which time the gap a is maximum), the bending force F is 0.119 N when the nickel-copper alloy material is used (not in the range of F of 0.15N-0.4N); the bending force F is 0.183 N when the stainless steel alloy material is used (in the range of F of 0.15N-0.4N); and the bending force F is 0.155 N when the stainless steel alloy and copper alloy composite material is used (in the range of F of 0.15N-0.4N). Therefore, when the stretch δ of the stainless steel alloy and nickel-copper alloy composite material is reduced from 0.0003 m to 0.00012 m, both are in the range of F of 0.15N-0.4N. Compared with the nickel-copper alloy and stainless steel alloy materials, this composite material better meets the elastic force control requirements, improves the welding process strength, and enhances product quality and life.

[0047] Specifically, the thermal protector is connected to the compressor via the compressor three-core terminal. Simply insert pin 1 into the compressor three-core terminal; at the same time, the connecting plug of the static pin 2 6 is used as the power connection; then insert the starter into the compressor three-core terminal and make an electrical connection, and it can be put into normal use. When the grid voltage is too high or too low or the refrigeration system fails, the bimetallic strip 44 is deformed by heat, pushing the contact of the dynamic reed 3 away from the contact of the static pin 3 8, and the thermal protector is activated, thereby cutting off the above-mentioned protective circuit and protecting the compressor motor.

[0048] The pressure detection device in this embodiment (such as Figures 6-10 As shown in the figure, it is used to detect the pressure of the dynamic spring 3 in the thermal protector. The dynamic spring pressure detection device includes a placement mechanism A, a pressing mechanism B and a testing mechanism C. The placement mechanism A is located below the pressing mechanism B and the testing mechanism C, and the pressing mechanism B and the testing mechanism C are both coordinated with the placement mechanism A.

[0049] The placing mechanism A in this embodiment includes a placing seat A1 and a cylinder A2. The placing seat A1 is connected to the piston rod of the cylinder A2. The cylinder barrel of the cylinder A2 is equipped with a No. 1 sensor SQ1 and a No. 2 sensor SQ2. The pressing mechanism B includes a pressing plate B1 and a cylinder B2. The pressing plate B1 is connected to the piston rod of the cylinder B2. The cylinder barrel of the cylinder B2 is equipped with a No. 3 sensor SQ3 and a No. 4 sensor SQ4. The testing mechanism C includes a connecting rod C1, a cylinder C2, a force sensor SQ1 and a No. 2 sensor SQ2. Sensor C3, cylinder four C4 and pull rod C5, connecting rod C1 is connected to the cylinder barrel of cylinder three C2, the piston rod of cylinder three C2 is connected to the cylinder barrel of cylinder four C4, the piston rod of cylinder four C4 is connected to force sensor C3, force sensor C3 is connected to pull rod C5, pull rod C5 is provided with a slot C5-1, sensor No. 5 SQ5 and sensor No. 6 SQ6 are installed on the cylinder barrel of cylinder three C2, sensor No. 7 SQ7 and sensor No. 8 SQ8 are installed on the cylinder barrel of cylinder four C4.

[0050] The pressure detection device of the dynamic reed is controlled by a control system, which includes a programmable controller PLC (model FP2SH) and a force measurement and control transmitter CK (model TB3K1). The programmable controller PLC includes a central processing unit CPU (model FP2-C2L), an analog-to-digital converter AD (model FP2-AD8VI), an input interface IN (model FP2-X16D2) and an output interface OUT (model FP2-Y16T). The force measurement and control transmitter CK is connected to the analog-to-digital converter AD, and the analog-to-digital converter AD, the input interface IN and the output interface OUT are all connected to the central processing unit CPU.

[0051] The input positive terminal I+ and negative terminal I- of the force sensor C3 are respectively connected to the excitation voltage positive terminal EXC+ and negative terminal EXC- of the force measurement and control transmitter CK, the output positive terminal O+ and negative terminal O- of the force sensor C3 are respectively connected to the signal voltage positive terminal SIG+ and negative terminal SIG- of the force measurement and control transmitter CK, the analog signal output positive terminal A+ and negative terminal A- of the force measurement and control transmitter CK are respectively connected to the positive + terminal and negative - terminal of the analog-to-digital converter AD, and the digital signal converted by the analog-to-digital converter AD is input into the central processing unit CPU.

[0052] The X0 terminal of the input interface IN is connected to the static pin 3 8 of the thermal protector RB under test, the static pin 2 6 of the thermal protector RB under test is connected to the negative terminal V- of the DC power supply, the X1-X8 terminals (i.e., terminals X1, X2, X3, X4, X5, X6, X7, and X8) of the input interface IN are respectively connected to one end of sensor No. 1 SQ1, sensor No. 2 SQ2, sensor No. 3 SQ3, sensor No. 4 SQ4, sensor No. 5 SQ5, sensor No. 6 SQ6, sensor No. 7 SQ7, and sensor No. 8 SQ8, the other ends of sensor No. 1 SQ1, sensor No. 2 SQ2, sensor No. 3 SQ3, sensor No. 4 SQ4, sensor No. 5 SQ5, sensor No. 6 SQ6, sensor No. 7 SQ7, and sensor No. 8 SQ8 are all connected to the negative terminal V- of the DC power supply, the common terminal COM of the input interface IN is connected to the positive terminal V+ of the DC power supply, and the input signal is transmitted to the central processing unit CPU through the input interface IN.

[0053] The Y0-Y3 terminals (i.e., Y0, Y1, Y2, and Y3) of the output interface OUT are respectively connected to one terminal of solenoid valve 1 FA2, solenoid valve 2 FB2, solenoid valve 3 FC2, and solenoid valve 4 FC4. The other terminals of solenoid valve 1 FA2, solenoid valve 2 FB2, solenoid valve 3 FC2, and solenoid valve 4 FC4 are all connected to the positive terminal V+ of the DC power supply. The negative terminal - of the output interface OUT is connected to the negative terminal V- of the DC power supply. The solenoid valve 1 FA2, solenoid valve 2 FB2, solenoid valve 3 FC2, and solenoid valve 4 FC4 are respectively connected to cylinder 1 A2, cylinder 2 B2, cylinder 3 C2, and cylinder 4 C4 through air pipes. The output signal of the central processing unit CPU controls the air path switching of each solenoid valve through the output interface OUT, and the switched air path controls each cylinder to perform the corresponding action.

[0054] The detection method of the pressure detection device is as follows: S1. Set the range parameters of the force test of the dynamic spring 3 of the thermal protector, and set the lower limit value F1 = 0.15N and the upper limit value F2 = 0.4N respectively.

[0055] S2. Place the thermal protector RB under test on the placement seat A1. After the test starts, the central processing unit CPU automatically runs the test process according to the program design requirements. First, it detects whether each test action is in the original position through the input interface IN. The original position signal of cylinder 1 A2, that is, sensor No. 1 SQ1, has a connection signal, the original position signal of cylinder 2 B2, that is, sensor No. 3 SQ3, has a connection signal, the original position signal of cylinder 3 C2, that is, sensor No. 5 SQ5, has a connection signal, and the original position signal of cylinder 4 C4, that is, sensor No. 7 SQ7, has a connection signal. The X0 end of the input interface IN should have a connection signal, that is, the thermal protector RB under test should be in a closed state. If all positions are in the original position, execute the next action.

[0056] S3, the output interface OUT is connected to the Y0 terminal control signal, the solenoid valve FA2 is energized, the air circuit control cylinder A2 sends the thermal protector RB to the specified test position, and the X2 terminal of the input interface IN receives the delivery in place signal from the second sensor SQ2 and then performs the next action control.

[0057] S4, output interface OUT is connected to the control signal at terminal Y1, solenoid valve 2 FB2 is energized, and air circuit control cylinder 2 B2 pushes pressing plate B1 to the specified position above placement seat A1. After terminal X4 of input interface IN receives the pressing in place signal from sensor No. 4 SQ4, it proceeds to the next action control.

[0058] S5, the output interface OUT is connected to the control signal at the Y3 end, the solenoid valve FC4 is energized, the air circuit control cylinder 4 C4 with the power sensor C3 and the pull rod C5 descends to the side of the moving contact 3-2, and the X8 end of the input interface IN receives the descending position signal from the eighth sensor SQ8 and then performs the next action control.

[0059] S6, the output interface OUT is connected to the Y2 terminal control signal, the solenoid valve 3 FC2 is energized, the air circuit controls the cylinder 3 C2 to drive the cylinder 4 C4, the force sensor C3 and the pull rod C5 to move the slot C5-1 to the inner side of the moving contact 3-2, and the X6 terminal of the input interface IN receives the move-in-place signal from the sixth sensor SQ6 and then performs the next action control.

[0060] S7, output interface OUT cuts off the control signal of terminal Y3, solenoid valve 4 FC4 loses power, and air circuit control cylinder 4 C4 with force sensor C3 and pull rod C5 slowly rises. At this time, force sensor C3 is subjected to force to generate a force sampling electrical signal, which is converted and amplified by force measurement and control transmitter CK to generate an analog signal proportional to the pressure of the dynamic spring, and then converted into a digital signal by analog-to-digital converter AD and transmitted to the central processing unit CPU for calculation and processing; when the dynamic contact 3-2 is separated from the static contact 8-1, the X0 terminal of input interface IN receives the contact disconnection signal. At this time, the data obtained by the central processing unit CPU after calculation and processing is the bending elastic force F of the dynamic spring 3, which is saved at the same time. After the X7 terminal of input interface IN receives the rising position signal from sensor No. 7 SQ7, the next action control is carried out.

[0061] S8, output interface OUT is connected to the Y3 end control signal, solenoid valve 4 FC4 is energized, and the air circuit control cylinder 4 C4 with power sensor C3 and pull rod C5 descends; output interface OUT cuts off the Y2 end control signal, solenoid valve 3 FC2 loses power, and the air circuit control cylinder 3 C2 drives cylinder 4 C4, force sensor C3 and pull rod C5 to move the slot C5-1 to the outside of the moving contact 3-2; output interface OUT cuts off the Y3 end control signal, solenoid valve 4 FC4 loses power, and the air circuit control cylinder 4 C4 with power sensor C3 and pull rod C5 Rise; the output interface OUT cuts off the control signal at the Y1 end, the solenoid valve 2 FB2 loses power, and the air circuit control cylinder 2 B2 drives the pressing plate B1 to rise; the output interface OUT cuts off the control signal at the Y0 end, the solenoid valve 1 FA2 loses power, and the air circuit control cylinder 1 A2 drives the placement seat A1 to retract. At this time, all test actions have returned to their original positions. After the input interface IN receives the original position signals from sensor No. 7 SQ7, sensor No. 5 SQ5, sensor No. 3 SQ3, and sensor No. 1 SQ1, the test cycle of a product is completed.

[0062] S9. The central processing unit CPU compares the stored bending elastic force F with the set lower limit value F1 and upper limit value F2 for determination. If F1<F<F2, the thermal protector RB under test is qualified; if F<F1 or F>F2, the thermal protector RB under test is defective.

[0063] Force sensor C3: samples the pressure signal of the dynamic reed 3, and converts the force sampling signal into a weak electrical signal and inputs it into the force measurement and control transmitter CK for processing.

[0064] Force measurement and control transmitter CK: The positive terminal EXC+ and the negative terminal EXC- of the excitation voltage provide the working power supply of the force sensor C3, receive the force sampling electrical signal input by the force sensor C3, convert and amplify it, and output the analog signal from the output terminals A+ and A- to the input terminal of the analog-to-digital converter AD.

[0065] Analog-to-digital converter AD: converts analog signals into digital signals and transmits them to the central processing unit CPU.

[0066] Input interface IN: Receives switch signals from various sensors and switches and transmits them to the central processing unit CPU.

[0067] Output interface OUT: outputs the execution signal of the central processing unit CPU to each execution mechanism, and the execution mechanism performs the corresponding action.

[0068] Central Processing Unit (CPU): The core control component of the control system. Its working principle is to receive input signals from the input interface IN and the analog-to-digital converter AD, and perform logic control and data processing according to program design requirements. According to the processing results, it outputs corresponding control signals at the output interface OUT to realize the control of various functions.

[0069] Solenoid valve FA2: accepts electrical control from the Y0 end of the output interface OUT, and controls the cylinder A2 to perform actions through air circuit switching.

[0070] Solenoid valve 2 FB2: accepts electrical control from the Y1 end of the output interface OUT, and controls cylinder 2 B2 to perform actions through air circuit switching.

[0071] Solenoid valve three FC2: accepts electrical control from the Y2 end of the output interface OUT, and controls cylinder three C2 to perform actions through air circuit switching.

[0072] Solenoid valve four FC4: accepts electrical control from the Y3 end of the output interface OUT, and controls the cylinder four C4 to perform the action through gas circuit switching.

[0073] In addition, it should be noted that the shapes and names of the parts and components of the specific embodiments described in this specification may be different, and the above content described in this specification is merely an example of the structure of the present invention. Any equivalent changes or simple changes made based on the structure, features and principles described in the present invention are included in the protection scope of the present invention. Those skilled in the art of the present invention can make various modifications or supplements to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A thermal protector comprising a pin, a cover, a movable spring, a bimetallic strip, a first stationary leg, a second stationary leg, a heating element, a third stationary leg, and a base, wherein a pad is welded to one end of the movable spring, a movable contact is welded to the other end of the movable spring, a bump is provided at the center of the movable spring, a stationary contact is welded to one end of the third stationary leg, and the pad is electrically connected to the first stationary leg, characterized in that: When the moving contact (3-2) contacts the static contact (8-1), the moving spring (3) is arranged in an arc-shaped structure. At this time, a gap a is maintained between the protrusion (3-3) and the bimetallic strip (4). The value of the force generated by the variable when the moving spring (3) forms the arc-shaped structure is the test value of the bending elastic force F. The moving spring (3) is made of a multi-layer composite material of copper alloy and stainless steel. The calculation process of the bending force F is as follows: (Formula 1) Where K represents the bending stiffness coefficient, δ represents the stretching amount, (Formula 2) Where E represents the elastic modulus, b represents the width of the dynamic reed, h represents the thickness of the dynamic reed, and L represents the length of the dynamic reed.

2. The thermal protector according to claim 1, characterized in that: The pin (1) is arranged on the cover plate (2), and the movable spring (3), bimetallic strip (4), static foot one (5), static foot two (6), heating element (7), and static foot three (8) are all arranged in a cavity formed by the cover plate (2) and the base (9), and the heating element (7), bimetallic strip (4), and movable spring (3) are arranged in sequence from bottom to top.

3. The thermal protector according to claim 1, characterized in that: The two ends of the heating element (7) are respectively welded to the static foot one (5) and the static foot two (6), one end of the movable spring (3) is electrically connected to the static foot one (5), the other end of the movable spring (3) cooperates with one end of the static foot three (8), and the other end of the static foot three (8) is electrically connected to the plug pin (1). When the other end of the movable spring (3) contacts one end of the static foot three (8), the static foot two (6), the heating element (7), the static foot one (5), the movable spring (3), the static foot three (8), and the plug pin (1) are connected in sequence to form an electrical circuit.

4. A pressure detection device for a movable spring, the pressure detection device for a movable spring being used to detect the pressure of a movable spring (3) in a thermal protector according to any one of claims 1 to 3, characterized in that: The pressure detection device of the movable spring comprises a placing mechanism (A), a pressing mechanism (B) and a testing mechanism (C). The placing mechanism (A) is located below the pressing mechanism (B) and the testing mechanism (C), and the pressing mechanism (B) and the testing mechanism (C) both cooperate with the placing mechanism (A).

5. The pressure detection device of the dynamic spring according to claim 4, characterized in that: The placement mechanism (A) comprises a placement seat (A1) and a cylinder 1 (A2). The placement seat (A1) is connected to the piston rod of the cylinder 1 (A2). A first sensor (SQ1) and a second sensor (SQ2) are installed on the cylinder barrel of the cylinder 1 (A2).

6. The pressure detection device for a movable spring according to claim 5, characterized in that: The pressing mechanism (B) includes a pressing plate (B1) and a second cylinder (B2). The pressing plate (B1) is connected to the piston rod of the second cylinder (B2). A third sensor (SQ3) and a fourth sensor (SQ4) are installed on the cylinder barrel of the second cylinder (B2).

7. The pressure detection device for a movable spring according to claim 6, characterized in that: The testing mechanism (C) includes a connecting rod (C1), cylinder three (C2), a force sensor (C3), cylinder four (C4) and a pull rod (C5), wherein the connecting rod (C1) is connected to the cylinder barrel of cylinder three (C2), the piston rod of cylinder three (C2) is connected to the cylinder barrel of cylinder four (C4), the piston rod of cylinder four (C4) is connected to the force sensor (C3), the force sensor (C3) is connected to the pull rod (C5), a slot (C5-1) is provided on the pull rod (C5), a No. 5 sensor (SQ5) and a No. 6 sensor (SQ6) are installed on the cylinder barrel of cylinder three (C2), and a No. 7 sensor (SQ7) and a No. 8 sensor (SQ8) are installed on the cylinder barrel of cylinder four (C4).

8. The pressure detection device for a movable spring according to claim 7, characterized in that: The pressure detection device of the dynamic spring is controlled by a control system, which includes a programmable controller (PLC) and a force measurement and control transmitter (CK). The programmable controller (PLC) includes a central processing unit (CPU), an analog-to-digital converter (AD), an input interface (IN), and an output interface (OUT). The force measurement and control transmitter (CK) is connected to the analog-to-digital converter (AD), and the analog-to-digital converter (AD), the input interface (IN), and the output interface (OUT) are all connected to the central processing unit (CPU).

9. The pressure detection device for a movable spring according to claim 8, characterized in that: The positive input terminal and negative input terminal of the force sensor (C3) are respectively connected to the positive excitation voltage terminal and negative excitation voltage terminal of the force measurement and control transmitter (CK); the positive output terminal and negative output terminal of the force sensor (C3) are respectively connected to the positive signal voltage terminal and negative signal terminal of the force measurement and control transmitter (CK); the positive analog signal output terminal and negative analog signal output terminal of the force measurement and control transmitter (CK) are respectively connected to the positive analog signal output terminal and negative analog signal output terminal of the force measurement and control transmitter (CK); and the digital signal converted by the analog digital converter (AD) is input to a central processing unit (CPU); The X0 end of the input interface (IN) is connected to the static pin 3 (8) of the thermal protector (RB) under test, the static pin 2 (6) of the thermal protector (RB) under test is connected to the negative end of the DC power supply, the X1-X8 ends of the input interface (IN) are respectively connected to one end of sensor No. 1 (SQ1), sensor No. 2 (SQ2), sensor No. 3 (SQ3), sensor No. 4 (SQ4), sensor No. 5 (SQ5), sensor No. 6 (SQ6), sensor No. 7 (SQ7), and sensor No. 8 (SQ8), the other ends of sensor No. 1 (SQ1), sensor No. 2 (SQ2), sensor No. 3 (SQ3), sensor No. 4 (SQ4), sensor No. 5 (SQ5), sensor No. 6 (SQ6), sensor No. 7 (SQ7), and sensor No. 8 (SQ8) are all connected to the negative end of the DC power supply, the common end COM of the input interface (IN) is connected to the positive end of the DC power supply, and the input signal is transmitted to the central processing unit (CPU) through the input interface (IN); The Y0-Y3 ends of the output interface (OUT) are respectively connected to one end of solenoid valve 1 (FA2), solenoid valve 2 (FB2), solenoid valve 3 (FC2), and solenoid valve 4 (FC4); the other ends of solenoid valve 1 (FA2), solenoid valve 2 (FB2), solenoid valve 3 (FC2), and solenoid valve 4 (FC4) are all connected to the positive end of a DC power supply; the negative end of the output interface (OUT) is connected to the negative end of a DC power supply; the solenoid valve 1 (FA2), solenoid valve 2 (FB2), solenoid valve 3 (FC2), and solenoid valve 4 (FC4) are respectively connected to cylinder 1 (A2), cylinder 2 (B2), cylinder 3 (C2), and cylinder 4 (C4) through air pipes; the output signal of the central processing unit (CPU) controls each solenoid valve to switch the air path through the output interface (OUT), and the switched air path controls each cylinder to perform a corresponding action.

10. A detection method for the pressure detection device of the movable spring according to claim 9, characterized in that: The detection method is as follows: S1. Set the range parameters of the force test of the dynamic spring (3) of the thermal protector, and set the lower limit value F1 = 0.15N and the upper limit value F2 = 0.4N respectively; S2. Place the thermal protector (RB) under test on the placement seat (A1). After the test starts, the central processing unit (CPU) automatically runs the test process according to the program design requirements. First, it checks through the input interface (IN) whether each test action is in the original position. If all positions are in the original position, the next action is executed; S3, the output interface (OUT) is connected to the control signal at the Y0 terminal, the solenoid valve 1 (FA2) is energized, and the air circuit control cylinder 1 (A2) sends the thermal protector (RB) to the specified test position. The input interface (IN) X2 receives the delivery position signal from the second sensor (SQ2) and then performs the next action control. S4, the output interface (OUT) is connected to the control signal at the Y1 terminal, the solenoid valve 2 (FB2) is energized, and the air circuit controls the cylinder 2 (B2) to push the pressing plate (B1) to the specified position above the placement seat (A1). The X4 terminal of the input interface (IN) receives the pressing in place signal from the fourth sensor (SQ4) and then performs the next action control. S5, the output interface (OUT) is connected to the control signal at the Y3 terminal, the solenoid valve 4 (FC4) is energized, the air circuit control cylinder 4 (C4) with the power sensor (C3) and the pull rod (C5) descends to the side of the moving contact (3-2), and the X8 terminal of the input interface (IN) receives the descending position signal from the eighth sensor (SQ8) and performs the next action control; S6, the output interface (OUT) is connected to the control signal at the Y2 end, solenoid valve three (FC2) is energized, and the air circuit controls cylinder three (C2) to drive cylinder four (C4), force sensor (C3) and pull rod (C5) to move the card slot (C5-1) to the inner side of the moving contact (3-2). The X6 end of the input interface (IN) receives the moving position signal from sensor number six (SQ6) and then performs the next action control. S7, the output interface (OUT) cuts off the control signal at the Y3 end, the electromagnetic valve four (FC4) loses power, and the air circuit control cylinder four (C4) with the power sensor (C3) and the pull rod (C5) slowly rises. At this time, the force sensor (C3) is subjected to force to generate a force sampling electrical signal. This signal is converted and amplified by the force measurement and control transmitter (CK) to generate an analog signal proportional to the pressure of the dynamic spring. It is then converted into a digital signal by the analog-to-digital converter (AD) and transmitted to the central processing unit (CPU) for calculation and processing. When the dynamic contact (3-2) and the static contact (8-1) are separated, the X0 end of the input interface (IN) receives a contact disconnection signal. At this time, the data obtained by the central processing unit (CPU) after calculation and processing is the bending elastic force F of the dynamic spring (3), which is saved at the same time. After the X7 end of the input interface (IN) receives the rising position signal from the seventh sensor (SQ7), the next action control is carried out. S8, the output interface (OUT) is connected to the Y3 end control signal, the solenoid valve four (FC4) is energized, and the air circuit control cylinder four (C4) with the power sensor (C3) and the pull rod (C5) descends; the output interface (OUT) cuts off the Y2 end control signal, the solenoid valve three (FC2) loses power, the air circuit control cylinder three (C2) drives the cylinder four (C4), the force sensor (C3) and the pull rod (C5) to move the slot (C5-1) to the outside of the moving contact (3-2); the output interface (OUT) cuts off the Y3 end control signal, the solenoid valve four (FC4) loses power, the air circuit control cylinder four (C4) with the power sensor (C3) and the pull rod (C5) descends. The rod (C5) rises; the output interface (OUT) cuts off the control signal at the Y1 end, the solenoid valve 2 (FB2) loses power, and the air circuit control cylinder 2 (B2) drives the pressing plate (B1) to rise; the output interface (OUT) cuts off the control signal at the Y0 end, the solenoid valve 1 (FA2) loses power, and the air circuit control cylinder 1 (A2) drives the placement seat (A1) to retract. At this time, all test actions have returned to their original positions. After the input interface (IN) receives the original position signals from sensor No. 7 (SQ7), sensor No. 5 (SQ5), sensor No. 3 (SQ3), and sensor No. 1 (SQ1), the test cycle of a product ends; S9. The central processing unit (CPU) compares the stored bending elastic force F with the set lower limit value F1 and upper limit value F2 for determination. If F1 < F < F2, the thermal protector (RB) under test is qualified; if F < F1 or F > F2, the thermal protector (RB) under test is defective.

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