Detection circuit for contact resistance values of an elevator door lock switch

Abstract

The utility model relates to detection loop of contact resistance value of elevator door lock switch. Detection loop includes the excitation module and door lock switch that mutually connect to constitute detection loop, and excitation module is configured as one of first excitation module and second excitation module. First excitation module includes DC voltage source and series resistance, and the positive pole and negative pole of DC voltage source are connected to the both ends of door lock switch through series resistance respectively. Second excitation module includes constant current source, and the positive pole and negative pole of constant current source are connected to the both ends of door lock switch respectively. The detection loop of the utility model can calculate the contact resistance value of elevator door lock switch, and the contact resistance value of elevator door lock switch can be used as the basis for determining the contact state of elevator door lock switch, and timely predicting poor contact of door lock switch is beneficial to elevator fault detection maintenance and predictive maintenance, and improves elevator operation safety.

Description

Technical Field

[0001] This utility model relates to the technical field of elevator safety operation detection, and in particular to a detection circuit for the contact resistance value of elevator door lock switches. Background Technology

[0002] Figure 1 This is a schematic diagram of the connection structure of the elevator door lock switch and safety circuit in an existing elevator system. (For example...) Figure 1 As shown, the door lock switch 11 and safety circuit 12 are connected in series. When the hall door and car door are closed, the door lock switch 11 is closed due to contact, the safety circuit 12 is connected, and the elevator operates normally. However, aging, wear, oxidation, and corrosion of the elevator door lock switch 11 can easily cause poor contact, resulting in a situation where the hall door and car door are closed, but the safety circuit 12 is not connected, and the elevator cannot operate. Poor contact of the door lock switch 11 is often concealed, and currently there is a lack of real-time and effective detection and early warning methods. The fault is usually only discovered and repaired after a user complaint. Since the common root cause of poor contact in the door lock switch 11 is excessive contact resistance, the poor contact condition of the door lock switch can be detected and warned by measuring the contact resistance value of the door lock switch 11.

[0003] The above description of the background technology is only for the purpose of facilitating a deeper understanding of the technical solution of this utility model (the technical means used, the technical problems solved, and the technical effects produced, etc.), and should not be regarded as an admission or in any form an implication that the information constitutes prior art known to those skilled in the art. Utility Model Content

[0004] The purpose of this invention is to provide a detection circuit for the contact resistance value of an elevator door lock switch, which can be used to calculate the contact resistance value of the elevator door lock switch.

[0005] According to one embodiment of the present invention, a detection circuit for the contact resistance value of an elevator door lock switch is provided, comprising an excitation module and a door lock switch interconnected to form a detection circuit. The excitation module is configured as one of a first excitation module and a second excitation module. The first excitation module includes a DC voltage source and a series resistor. The positive and negative terminals of the DC voltage source are respectively connected to the two ends of the door lock switch through the series resistor, thereby forming a detection circuit with the door lock switch to calculate the contact resistance value of the door lock switch based on the output voltage of the DC voltage source, the voltage across the series resistor, and the resistance value of the series resistor. The second excitation module includes a constant current source. The positive and negative terminals of the constant current source are respectively connected to the two ends of the door lock switch to calculate the contact resistance value of the door lock switch based on the voltage across the door lock switch and the output current of the constant current source.

[0006] The excitation module may further include at least one first relay, which is connected in series with the door lock switch in the detection circuit.

[0007] The first excitation module may further include two first relays; the positive terminal of the DC voltage source is connected to the first terminal of the door lock switch, the negative terminal of the DC voltage source is connected to the first terminal of the series resistor, the second terminal of the series resistor is connected to the second terminal of the door lock switch, one first relay is connected between the positive terminal of the DC voltage source and the first terminal of the door lock switch, and the other first relay is connected between the second terminal of the series resistor and the second terminal of the door lock switch.

[0008] The second excitation module further includes two first relays; the positive terminal of the constant current source is connected to the first terminal of the door lock switch, the negative terminal of the constant current source is connected to the second terminal of the door lock switch, one first relay is connected between the positive terminal of the constant current source and the first terminal of the door lock switch, and the other first relay is connected between the negative terminal of the constant current source and the second terminal of the door lock switch.

[0009] The present invention adopts the above technical solution and has the following beneficial effects: The detection circuit of the present invention can be used to calculate the contact resistance value of the elevator door lock switch. The contact resistance value of the elevator door lock switch can be used as the basis for determining the contact state of the elevator door lock switch. Timely prediction of poor contact of the door lock switch is conducive to elevator fault detection, repair and predictive maintenance, and improves elevator operation safety. Attached Figure Description

[0010] The exemplary embodiments of this utility model will be described in more detail below with reference to the accompanying drawings. For clarity, the same components in different drawings are shown with the same reference numerals. It should be noted that the drawings are for illustrative purposes only and are not necessarily drawn to scale. In these drawings:

[0011] Figure 1 This is a schematic diagram of the connection structure of the elevator door lock switch and safety circuit in an existing elevator system.

[0012] Figure 2 This is a block diagram of a detection system that includes a detection circuit for detecting the contact resistance value of an elevator door lock switch according to an embodiment of the present invention.

[0013] Figure 3 This is a schematic diagram of the structure of an elevator door lock switch contact resistance value detection system according to an exemplary embodiment.

[0014] Figure 4 This is a schematic diagram of the structure of an elevator door lock switch contact resistance detection system according to another implementation scheme.

[0015] Figure 5 yes Figure 3A schematic diagram of the door lock switch in a short-circuited state.

[0016] Figure 6 yes Figure 4 A schematic diagram of the door lock switch in a short-circuited state.

[0017] Figure 7 This is a flowchart of a detection method using a detection circuit for the contact resistance value of an elevator door lock switch according to an embodiment of the present invention. Detailed Implementation

[0018] The following provides a detailed description of the implementation scheme of this utility model. This implementation scheme is carried out based on the technical solution of this utility model and provides detailed implementation methods and specific operation processes. However, the protection scope of this utility model is not limited to the following implementation scheme.

[0019] Figure 2 This is a block diagram of a detection system including a detection circuit for detecting the contact resistance value of an elevator door lock switch according to an embodiment of the present invention. Figure 2 As shown, a detection system (hereinafter referred to as the elevator door lock switch contact resistance value detection system) including a detection circuit for the contact resistance value of an elevator door lock switch according to an embodiment of the present invention includes an excitation module 13, a sampling module 20, a calculation module 30, and a control module 40.

[0020] The excitation module 13 is configured to generate an electrical excitation signal, connect to the door lock switch 11 to form a detection circuit 10, and send the generated electrical excitation signal to the door lock switch 11.

[0021] The electrical excitation signal generated by the excitation module 13 can take forms including, but not limited to, voltage signals and current signals. In this case, the excitation module 13 may include a power supply with a constant voltage or current, or a power supply with a voltage or current exhibiting a specific variation pattern, to generate the electrical excitation signal. That is, the characteristics of the electrical excitation signal include, but are not limited to, DC, AC, pulse width modulation (PWM), triangular wave, or other signals with specific time-frequency characteristics (or variation patterns) to distinguish them from other interference signals in the circuit. Preferably, by using an electrical excitation signal with good autocorrelation characteristics, signals caused by the door lock switching characteristics can be easily distinguished from the acquired signals in subsequent processes, and noise signals can be eliminated, achieving the purpose of anti-interference.

[0022] In addition, the excitation module 13 and the safety circuit 12 can be isolated by means of isolation power supply, filter, relay, etc., so as to realize online detection of the contact resistance value of the door lock switch 11 during elevator operation.

[0023] The sampling module 20 is configured to: respond to the electrical excitation signal generated by the detection circuit 10, collect the electrical response signal from the excitation module 13 and obtain the information of the electrical response signal.

[0024] The electrical response signal can take forms including, but is not limited to, voltage and current signals. After acquiring the electrical response signal, the sampling module 20 can perform signal processing on the acquired electrical response signal to obtain information about the electrical response signal. Signal processing is used to convert the acquired electrical response signal into a signal that contains the characteristics of the contact resistance value of the door lock switch 11 and is easy to calculate, in order to obtain information about the electrical response signal. The form of the converted electrical response signal includes, but is not limited to, analog and digital signals.

[0025] The calculation module 30 is configured to calculate the contact resistance value of the door lock switch 11 based on the information of the electrical excitation signal and the information of the electrical response signal obtained by the sampling module 20.

[0026] The calculation module 30 receives the electrical response signal information acquired by the sampling module 20, and calculates the contact resistance value of the door lock switch 11 based on the pre-stored information of the electrical excitation signal generated by the excitation module 13. The calculation methods include, but are not limited to, basic comparison methods, addition, subtraction, multiplication, division, time-frequency conversion, frequency domain calculation, and combinations of multiple calculation methods.

[0027] In addition, the carrier of the computing module 30 includes, but is not limited to, analog computing circuits built on chips, microcontroller units (MCUs), field programmable gate arrays (FPGAs), etc.

[0028] The control module 40 is configured to determine whether the door lock switch 11 has poor contact based on the contact resistance value calculated by the calculation module 30. Methods for determining whether the door lock switch 11 has poor contact include, but are not limited to, the threshold method and the state comparison method.

[0029] In a preferred embodiment, the control module 40 can control whether the electrical excitation signal generated by the excitation module 13 can be sent to the door lock switch 11.

[0030] In other preferred embodiments, after determining that the door lock switch 11 has poor contact, the control module 40 can perform fault warning and safety protection actions, including but not limited to recording status information and uploading fault information to the cloud.

[0031] exist Figure 2In the example of the system configuration shown, the excitation module 13, sampling module 20, calculation module 30, and control module 40 are divided according to their functions. In actual circuits, multiple modules may be integrated into one entity, or the function of one module may be implemented by multiple entities. The calculation module 30 may be merged into the control module 40 or omitted. All such modifications should be included within the protection scope of this utility model.

[0032] The following section provides a detailed description of a system for detecting the contact resistance value of an elevator door lock switch, using two specific exemplary embodiments as examples. Figure 3 and Figure 4 This is a schematic diagram of a system for detecting the contact resistance value of an elevator door lock switch. (Example:) Figure 3 and Figure 4 As shown, two door lock switch units 11a and 11b connected in series are exemplarily used as the door lock switch 11 under test. When the control module 40 determines that the door lock switch 11 has poor contact, it indicates that at least one door lock switch unit has poor contact. However, the door lock switch under test includes, but is not limited to, a series path of two door lock switch units, and can also be a series path of one or more door lock switch units.

[0033] The stimulus module can be configured as follows: Figure 3 The excitation module shown and Figure 4 One of the excitation modules shown.

[0034] In one exemplary implementation, such as Figure 3 As shown, the excitation module 13 includes a DC voltage source 14 and a series resistor 15. The positive and negative terminals of the DC voltage source 14 are connected to the two ends of the door lock switch 11 through the series resistor 15. For example, the positive terminal of the DC voltage source 14 is connected to the first end of the door lock switch (end a in the figure), the negative terminal of the DC voltage source 14 is connected to the first end of the series resistor 15 (end c in the figure), and the second end of the series resistor 15 (end d in the figure) is connected to the second end of the door lock switch 11 (end b in the figure). Therefore, the excitation module 13 and the door lock switch 11 form a detection circuit 10, and the output voltage signal of the DC voltage source 14 is sent to the door lock switch 11 as an electrical excitation signal.

[0035] The sampling module 20 is implemented as an analog-to-digital converter (ADC) 21. The ADC 21 is configured to acquire the voltage signal generated by the output voltage signal of the DC voltage source 14 of the series resistor 15 in the detection circuit 10 as an electrical response signal to obtain the voltage across the series resistor 15.

[0036] The calculation module 30 and the control module 40 are integrated on the MCU 50, which is configured to calculate the contact resistance value of the door lock switch 11 according to the following formula (1):

[0037]

[0038] In formula (1) above, R is the contact resistance value of the door lock switch 11. p R1 is the output voltage of DC voltage source 14, which serves as an electrical excitation signal and can be pre-stored in MCU 50. R1 is the resistance value of series resistor 15, which can also be pre-stored in MCU 50. U1 is the voltage across series resistor 15 acquired by ADC 21, which serves as an electrical response signal and is sent by ADC 21 to MCU 50.

[0039] As described above, the control module 40 can control whether the electrical excitation signal generated by the excitation module 13 can be sent to the door lock switch 11. To this end, the excitation module 13 may further include at least one first relay, which is connected in series with the door lock switch 11 in the detection circuit 10. For example, the excitation module 13 may further include two first relays 16a and 16b, one first relay (specifically, first relay 16a) connected between the positive terminal of the DC voltage source 14 and terminal a of the door lock switch 11, and the other first relay (specifically, first relay 16b) connected between terminal d of the series resistor 15 and terminal b of the door lock switch 11. The MCU 50 is configured to control the opening or closing of the first relays 16a and 16b. When both first relays 16a and 16b are closed, the output voltage signal of the DC voltage source 14 can be sent to the door lock switch 11, that is, the electrical excitation signal generated by the excitation module 13 can be sent to the door lock switch 11. Conversely, when either of the first relays 16a or 16b is disconnected, the output voltage signal of the DC voltage source 14 cannot be sent to the door lock switch 11, that is, the electrical excitation signal generated by the excitation module 13 cannot be sent to the door lock switch 11.

[0040] In another exemplary implementation, such as Figure 4 As shown, the excitation module 13 includes a constant current source 17, the positive and negative terminals of which are connected to the two ends of the door lock switch 11, respectively. For example, the positive terminal of the constant current source 14 is connected to terminal a of the door lock switch 11, and the negative terminal of the constant current source 17 is connected to terminal b of the door lock switch 11. Thus, the excitation module 13 and the door lock switch 11 form a detection circuit 10, and the output current signal of the constant current source 17 is sent to the door lock switch 11 as an electrical excitation signal.

[0041] and Figure 3Similar to the illustrated implementation, the excitation module 13 may further include at least one first relay, which is connected in series with the door lock switch 11 in the detection circuit 10. Therefore, the MCU 50 controls whether the electrical excitation signal generated by the excitation module 13 can be sent to the door lock switch 11 by controlling the opening or closing of the first relays 16a and 16b. For example, the first relay 16a is connected between the positive terminal of the constant current source 17 and terminal a of the door lock switch 11, and the first relay 16b is connected between the negative terminal of the constant current source 17 and terminal b of the door lock switch 11.

[0042] The ADC 21 is configured to use the voltage signal generated by the output current signal of the constant current source 17 of the door lock switch 11 in the detection circuit 10 as the electrical response signal to acquire the voltage across the door lock switch 11.

[0043] MCU 50 is configured to calculate the contact resistance value of door lock switch 11 according to the following formula (2):

[0044]

[0045] In the above formula (2), R is the contact resistance value of the door lock switch 11, and I p This is the output current of constant current source 17, and its information as an electrical excitation signal can be pre-stored in MCU 50. R The voltage across the door lock switch 11 is acquired by ADC 21, and this information, as an electrical response signal, is sent by ADC 21 to MCU 50.

[0046] After the calculation module 21 calculates the contact resistance value of the door lock switch 11, the control module 40 determines whether the door lock switch 11 has poor contact based on the contact resistance value calculated by the calculation module 30.

[0047] In one implementation, a threshold method is used to determine whether the door lock switch 11 has poor contact. The control module 40 compares the contact resistance value R of the door lock switch 11 calculated by the calculation module 30 with a first preset threshold (e.g., 100Ω). When the contact resistance value R of the door lock switch 11 calculated by the calculation module 30 is greater than the first preset threshold, the control module 40 can determine that the door lock switch has poor contact. Conversely, when the contact resistance value R of the door lock switch 11 calculated by the calculation module 30 is less than or equal to the first preset threshold, the control module 40 can determine that the door lock switch does not have poor contact.

[0048] In another implementation, a state comparison method is used to determine whether the door lock switch has poor contact. Specifically, Figure 5 yes Figure 3 A schematic diagram of the door lock switch in a short-circuited state. Figure 6 yes Figure 4 A schematic diagram showing the door lock switch in a short-circuited state. (Combined with...) Figure 5 and Figure 6 The excitation module 13 includes a second relay 19 and a shorting wire 18 for the door lock switch 11. The second relay 19 is connected in the shorting wire 18 and in parallel with the door lock switch 11. The control module 40 can control the opening or closing of the second relay 19 to control whether the door lock switch 11 is in a normal operating state or a short-circuited state. That is, when the control module 40 controls the second relay 19 to open, the door lock switch 11 is in a normal operating state, and when the control module 40 controls the second relay 19 to close, the door lock switch 11 is in a short-circuited state.

[0049] Combination Figure 3 and Figure 6 The acquisition module 20 (specifically, ADC 21) acquires the voltage across the series resistor 15 when the second relay 19 is open or closed.

[0050] The calculation module 30 (specifically, the MCU 50) calculates the resistance difference of the detection circuit 10 when the second relay 19 is open and closed according to the following formula (3):

[0051]

[0052] In the above formula (3), ΔR is the resistance difference of the detection circuit 10 when the second relay 19 is open and closed. p R1 is the output voltage of DC voltage source 14. R1 is the resistance value of series resistor 15. U1 is the voltage across series resistor 15 collected by sampling module 20 when second relay 19 is open, which is the same as U1 in formula (1). U2 is the voltage across series resistor 15 collected by sampling module 20 when second relay 19 is closed.

[0053] Combination Figure 4 and Figure 6 The acquisition module 20 (specifically, ADC 21) acquires the voltage across the door lock switch 11 when the second relay 19 is open or closed.

[0054] The calculation module (specifically, MCU 50) calculates the resistance difference of the detection circuit 10 when the second relay 19 is open and closed according to the following formula (6):

[0055]

[0056] In the above formula (6), ΔR is the resistance difference between the detection circuit 10 and the second relay 19 when it is open and closed. p It is the output current of a constant current source. U RIt is the voltage across the door lock switch 11 collected by the sampling module 20 when the second relay 19 is disconnected, which is related to U in formula (2). R Same. U ′ R It is the voltage across the door lock switch 11 collected by the sampling module 20 when the second relay 19 is closed.

[0057] In determining whether the door lock switch 11 has poor contact, the control module 40 compares the resistance difference ΔR calculated by the calculation module 30 with a second preset threshold (e.g., 100Ω). When the resistance difference ΔR is greater than the second preset threshold, the control module 40 determines that the door lock switch 11 has poor contact. Conversely, when the resistance difference ΔR is less than or equal to the second preset threshold, the control module 40 can determine that the door lock switch 11 has no poor contact.

[0058] Figure 7 This is a flowchart of a detection method for the contact resistance value of an elevator door lock switch using a detection circuit according to an embodiment of the present invention. The detection method for the contact resistance value of an elevator door lock switch using a detection circuit according to an embodiment of the present invention (hereinafter referred to as the elevator door lock switch contact resistance value detection method) is as follows: Figure 2 The system for detecting the contact resistance value of the elevator door lock switch shown is implemented. For example... Figure 7 As shown, the detection method includes the following steps: an electrical excitation signal is generated by the excitation module 13, forming a detection circuit 10 with the door lock switch 11, and the generated electrical excitation signal is sent to the door lock switch 11 (S71); an electrical response signal is generated by the electrical excitation signal in response to the detection circuit 10, and the sampling module 20 collects the electrical response signal from the excitation module 13 and obtains the information of the electrical response signal (S72); the calculation module 30 calculates the contact resistance value of the door lock switch 11 based on the information of the electrical excitation signal and the information of the electrical response signal collected by the sampling module 20 (S73); and the control module 40 determines whether the door lock switch 11 has poor contact based on the contact resistance value calculated by the calculation module 30 (S74).

[0059] exist Figure 3 In one specific embodiment shown, the excitation module 13 includes a DC voltage source and a series resistor 15. The positive and negative terminals of the DC voltage source are connected to the two ends of the door lock switch 11 through the series resistor 15, thereby forming a detection circuit between the excitation module 13 and the door lock switch 11. The output voltage signal of the DC voltage source is sent to the door lock switch 11 as an electrical excitation signal. In this case, the detection method includes the steps of: the sampling module 20 taking the voltage signal generated by the output voltage signal of the DC voltage source in the series resistor 15 in the detection circuit 10 as an electrical response signal to obtain the voltage across the series resistor 15; and the calculation module 30 calculating the contact resistance value of the door lock switch 11 according to the following formula:

[0060]

[0061] Where R is the contact resistance value of door lock switch 11, and U p R1 is the output voltage of DC voltage source 14, R1 is the resistance value of series resistor 15, and U1 is the voltage across series resistor 15 collected by sampling module 20.

[0062] exist Figure 4 In another specific embodiment shown, the excitation module 13 includes a constant current source 17, the positive and negative terminals of which are respectively connected to the two ends of the door lock switch 11. Thus, the excitation module 13 and the door lock switch 11 form a detection circuit. The output current signal of the constant current source 17 is sent to the door lock switch 11 as an electrical excitation signal. This detection method includes the following steps: the sampling module 20 takes the voltage signal generated by the output current signal of the constant current source 17 in the door lock switch 11 in the detection circuit as an electrical response signal to obtain the voltage across the door lock switch 11. The calculation module 30 calculates the contact resistance value of the door lock switch 11 according to the following formula:

[0063]

[0064] Where R is the contact resistance value of door lock switch 11, and U R It is the voltage across the door lock switch 11 collected by the sampling module 20, I p It is the output current of constant current source 17.

[0065] Combination Figure 3 and Figure 4 The excitation module 13 includes at least one first relay 16a, 16b, which is connected in series with the door lock switch 11 in the detection circuit. In this case, the detection method includes the step of controlling the first relays 16a, 16b to open or close, thereby controlling whether the electrical excitation signal generated by the excitation module 13 can be sent to the door lock switch 11.

[0066] According to one embodiment of the present invention, the step of determining whether the door lock switch 11 has poor contact includes: the control module 40 compares the contact resistance value R of the door lock switch 11 calculated by the calculation module 30 with a first preset threshold (e.g., 100Ω); when the contact resistance value R of the door lock switch 11 calculated by the calculation module 30 is greater than the first preset threshold, the control module 40 determines that the door lock switch 11 has poor contact.

[0067] Besides using the threshold method to determine whether the door lock switch 11 has poor contact, a state comparison method can also be used to determine whether the door lock switch 11 has poor contact. Specifically, combined with Figure 5and Figure 6 The excitation module 13 includes a second relay 19 and a shorting wire 18 for the door lock switch 11. The second relay 19 is connected in the shorting wire 18 and in parallel with the door lock switch 11. In this case, the detection method includes the steps of: the control module 40 controlling the second relay 19 to open or close, so as to control the door lock switch 11 to be in a normal working state or a short-circuited state; and the calculation module 30 calculating the resistance difference of the detection circuit 10 when the second relay 19 is open and closed.

[0068] Specifically, in Figure 3 and Figure 5 In one specific embodiment shown, the calculation module 30 calculates the resistance difference of the detection circuit 10 when the second relay 19 is open and closed according to the following formula:

[0069]

[0070] Where ΔR is the resistance difference between the detection circuit 10 and the second relay 19 when it is open and closed, U p R1 is the output voltage of DC voltage source 14, and R1 is the resistance value of series resistor 15. U1 is the voltage across series resistor 15 collected by sampling module 20 when second relay 19 is open, and U2 is the voltage across series resistor 15 collected by sampling module 20 when second relay 19 is closed.

[0071] exist Figure 4 and Figure 6 In another specific embodiment shown, the calculation module 30 calculates the resistance difference of the detection circuit 10 when the second relay 19 is open and closed according to the following formula:

[0072]

[0073] Wherein, ΔR is the resistance difference between the detection circuit 10 and the second relay 19 when it is open and closed, I p It is the output current of a constant current source, U R It is the voltage across the door lock switch 11 collected by the sampling module 20 when the second relay 19 is disconnected, U ′ R It is the voltage across the door lock switch 11 collected by the sampling module 20 when the second relay 19 is closed.

[0074] Subsequently, the control module 40 compares the resistance difference ΔR calculated by the calculation module 30 with a second preset threshold (e.g., 100Ω). When the calculated resistance difference ΔR is greater than the second preset threshold, the control module 40 determines that the door lock switch 11 has poor contact.

[0075] The contact resistance value of the elevator door lock switch can be calculated using the detection circuit of the embodiment of the present invention. The contact resistance value of the elevator door lock switch can be used as the basis for determining the contact state of the elevator door lock switch. Timely prediction of poor contact of the door lock switch is beneficial to elevator fault detection, repair and predictive maintenance, and improves elevator operation safety.

[0076] The various embodiments of this utility model are not an exhaustive list of all possible combinations, but are intended to describe representative aspects of the utility model, and the contents described in the various embodiments can be applied independently or in two or more combinations.

[0077] The description of the exemplary embodiments presented above is merely illustrative of the technical solutions of this utility model and is not intended to be exhaustive or to limit the utility model to the precise forms described. Obviously, those skilled in the art can make many changes and variations based on the above teachings. The exemplary embodiments were chosen and described to explain the specific principles of this utility model and its practical applications, thereby enabling others skilled in the art to understand, implement, and utilize the various exemplary embodiments of this utility model and their various alternatives and modifications. The scope of protection of this utility model is intended to be defined by the appended claims and their equivalents.

Claims

1. A circuit for detecting the contact resistance value of an elevator door lock switch, characterized in that, It includes an excitation module and a door lock switch that are interconnected to form a detection loop, wherein the excitation module is configured as one of a first excitation module and a second excitation module; The first excitation module includes a DC voltage source and a series resistor. The positive and negative terminals of the DC voltage source are connected to the two ends of the door lock switch through the series resistor, so that the first excitation module and the door lock switch form a detection circuit to calculate the contact resistance value of the door lock switch based on the output voltage of the DC voltage source, the voltage across the series resistor, and the resistance value of the series resistor. The second excitation module includes a constant current source, the positive and negative terminals of which are connected to the two ends of the door lock switch, respectively, to calculate the contact resistance value of the door lock switch based on the voltage across the door lock switch and the output current of the constant current source.

2. The detection circuit for the contact resistance value of the elevator door lock switch according to claim 1, characterized in that, The excitation module further includes at least one first relay, which is connected in series with the door lock switch in the detection circuit.

3. The detection circuit for the contact resistance value of the elevator door lock switch according to claim 2, characterized in that, The first excitation module further includes two first relays; The positive terminal of the DC voltage source is connected to the first terminal of the door lock switch, the negative terminal of the DC voltage source is connected to the first terminal of the series resistor, the second terminal of the series resistor is connected to the second terminal of the door lock switch, a first relay is connected between the positive terminal of the DC voltage source and the first terminal of the door lock switch, and another first relay is connected between the second terminal of the series resistor and the second terminal of the door lock switch.

4. The detection circuit for the contact resistance value of the elevator door lock switch according to claim 2, characterized in that, The second excitation module further includes two first relays; The positive terminal of the constant current source is connected to the first terminal of the door lock switch, the negative terminal of the constant current source is connected to the second terminal of the door lock switch, a first relay is connected between the positive terminal of the constant current source and the first terminal of the door lock switch, and another first relay is connected between the negative terminal of the constant current source and the second terminal of the door lock switch.

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