Aero-engine weak rotating speed signal measuring system

Abstract

The invention provides an aero-engine weak rotating speed signal measuring system, and belongs to the technical field of rotating speed signal acquisition, the aero-engine weak rotating speed signal measuring system comprises a weak rotating speed signal detection module, a load detection module, a rewinding self-checking module and a processor, and the rewinding self-checking module comprises a rotating speed simulation excitation circuit and a channel switching circuit. The load detection module comprises a load excitation circuit and a load excitation recovery circuit; the input end of the rotating speed simulation excitation circuit is connected with the processor, and the output end is connected with the input end of the channel switching circuit; the input end of the channel switching circuit is also connected with an external rotating speed sensor and the processor, the output end is connected with the input end of the weak rotating speed signal detection module, and the output end of the weak rotating speed signal detection module is connected with the processor; the input end of the load excitation circuit is connected with the processor, and the output end is connected with the rotating speed sensor. The input end of the load excitation recovery circuit is connected with the rotating speed sensor, and the output end is connected with the processor. According to the invention, the reliability, adaptability, safety and anti-interference capability are improved.

Description

Technical Field

[0001] This application relates to the field of speed signal acquisition technology, and in particular to a system for measuring weak speed signals of aero engines. Background Technology

[0002] As the core power unit of aircraft, the performance of aero-engines directly affects flight safety and efficiency. Engine speed signals, as crucial operating parameters, play a key role in engine control, fault diagnosis, and performance monitoring. During engine start-up or shutdown, the speed signal is weak and easily affected by electromagnetic interference, mechanical vibration, and environmental noise, leading to decreased measurement accuracy or even signal loss. This poses a serious challenge to engine reliability and safety. In practical applications, the operating environment of aero-engines is complex and variable. Load fluctuations, temperature changes, and vibration interference can significantly affect the measurement accuracy of the speed signal. Especially under weak signal conditions, traditional measurement methods often fail to meet accuracy and reliability requirements. Furthermore, most existing measurement systems focus on single speed signal detection, lacking real-time monitoring and self-checking capabilities for load changes, and cannot effectively address the measurement needs of complex operating environments.

[0003] In recent years, with the development of intelligent and automated technologies, the requirements for signal measurement in aero-engine control systems have become increasingly stringent. Especially during start-up and shutdown, accurately capturing weak speed signals and combining them with load detection and self-test functions is crucial for improving engine start-up success rates and operational reliability. However, current technologies have not yet effectively solved the problems of accuracy and reliability in weak signal measurement, nor have they achieved an organic integration of load detection and self-test functions. Summary of the Invention

[0004] In view of this, the embodiments of this application provide a weak speed signal measurement system for aero-engines. By designing a novel weak speed signal acquisition circuit, it achieves accurate capture of weak speed signals in complex environments. At the same time, it integrates online load detection and rewind self-test functions, which significantly improves the reliability and adaptability of the measurement system and provides important support for the intelligent control and safe operation of aero-engines.

[0005] This application provides a weak speed signal measurement system for an aero-engine. The system includes a weak speed signal detection module, a load detection module, a self-testing loop module, and a processor. The self-testing loop module includes a speed simulation excitation circuit and a channel switching circuit. The load detection module includes a load excitation circuit and a load excitation retrieval circuit. The input terminal of the speed simulation excitation circuit is connected to the output terminal of the processor, and the output terminal of the speed simulation excitation circuit is connected to the input terminal of the channel switching circuit. The input terminal of the channel switching circuit is also connected to an external speed sensor and the output terminal of the processor. The output terminal of the channel switching circuit is connected to the input terminal of the weak speed signal detection module, and the output terminal of the weak speed signal detection module is connected to the input terminal of the processor. The input terminal of the load excitation circuit is connected to the output terminal of the processor, and the output terminal of the load excitation retrieval circuit is connected to the speed sensor. The input terminal of the load excitation retrieval circuit is connected to the speed sensor, and the output terminal of the load excitation retrieval circuit is connected to the input terminal of the processor. The speed simulation excitation circuit receives control commands from the processor and generates an analog signal with the same voltage waveform as the external speed sensor. At the same time, the processor sends a control signal to enable the signal. The control channel switching circuit switches the analog signal to the weak speed signal acquisition module, where the processor performs frequency acquisition and compares it with the frequency source value generated by the external speed sensor to complete the self-test function. The load excitation circuit receives control commands from the processor and generates an excitation voltage. After passing through the external speed sensor, the load excitation feedback circuit acquires the voltage and determines the status of the external speed sensor by the feedback voltage value.

[0006] According to a specific implementation of an embodiment of this application, the weak signal detection module includes a filter clamping circuit, a signal amplification circuit, and a hysteresis comparator circuit connected in sequence. The filter clamping circuit includes a first-order passive low-pass filter circuit, a first-order passive high-pass filter circuit, and a clamping circuit. The first-order passive low-pass filter circuit and the first-order passive high-pass filter circuit are used to filter out high-frequency interference and DC components in the speed signal. The clamping circuit is used to limit the amplitude of the speed signal. The signal amplification circuit is used to amplify the amplitude of the speed signal. The hysteresis comparator circuit is used to convert the amplified speed signal into a square wave of the same frequency.

[0007] According to a specific implementation of this application, the weak signal detection module includes a second operational amplifier, multiple resistors, multiple capacitors, and multiple diodes. A fifth capacitor C5 and a first diode V1 and a second diode V2 configured in reverse are connected in parallel between the non-inverting and inverting input terminals of the second operational amplifier. The non-inverting input terminal of the second operational amplifier is also connected to one end of the speed sensor through a third capacitor C3 and a first resistor R1. The third capacitor C3 and the first resistor R1 are grounded through the first capacitor C1. The connection point between the non-inverting input terminal of the second operational amplifier and the positive terminal of the first diode V1 is grounded to the third capacitor C3 through the third resistor R3. The inverting input terminal of the second operational amplifier is also connected to the other end of the speed sensor through a fourth capacitor C4 and a second resistor R2. The fourth capacitor C4 and the second resistor R2 are grounded through the second capacitor C2. The connection point between the inverting input terminal of the second operational amplifier and the negative terminal of the first diode V1 is grounded through the fourth capacitor C4 through the fourth resistor R4. The fifth resistor R5 is connected in parallel between the non-inverting input terminal and the output terminal of the second operational amplifier. The output terminal of the second operational amplifier is connected to a hysteresis comparator circuit. The first diode V1 and the second diode V2 form a clamping circuit. The first resistor R1, the second resistor R2, the first capacitor C1 and the second capacitor C2 form a first-order passive low-pass filter circuit. The third resistor R3, the fourth resistor R4, the third capacitor C3 and the fourth capacitor C4 form a first-order passive high-pass filter circuit. The fifth capacitor C5 is used for differential mode noise filtering. The second operational amplifier and the fifth resistor R5 form a signal amplification circuit.

[0008] According to a specific implementation of an embodiment of this application, the hysteresis comparator circuit includes a comparator and multiple resistors. The inverting input terminal of the comparator is connected to the output terminal of the second operational amplifier through a sixth resistor R6. The non-inverting input terminal of the comparator is grounded through an eighth resistor R8 and a seventh resistor R7. A ninth resistor R9 is connected in parallel between the non-inverting input terminal and the output terminal of the comparator. The output terminal of the comparator is connected to the processor through an eleventh resistor R11. The output terminal of the comparator and the eleventh resistor R11 are grounded through a tenth resistor R10.

[0009] According to a specific implementation of an embodiment of this application, a second-order active filter circuit is provided between the speed simulation excitation circuit and the channel switching circuit.

[0010] According to a specific implementation of an embodiment of this application, the speed simulation excitation circuit is configured as a DAC, and the channel switching circuit includes a first analog switch.

[0011] According to a specific implementation of an embodiment of this application, the load detection module includes a second analog switch, a first operational amplifier, an AD conversion circuit, multiple resistors, multiple capacitors, and a third diode V3. The second analog switch is connected to the output terminal of the processor, a twelfth resistor R12, and a speed sensor, respectively. The other end of the twelfth resistor R12 is connected to a 15V voltage. The non-inverting input terminal of the first operational amplifier is connected to one end of the speed sensor through a thirteenth resistor R13, and the inverting input terminal of the first operational amplifier is connected to the other end of the speed sensor through a fourteenth resistor R14. The fourteenth resistor R14 and the speed sensor are grounded through a fifteenth resistor R15. The non-inverting input of the first operational amplifier is grounded through the sixth capacitor C6 between the thirteenth resistor R13 and the inverting input of the first operational amplifier. The fourteenth resistor R14 is grounded through the seventh capacitor C7. A third diode V3 and a resistor Rg are connected in parallel between the inverting input and the non-inverting input of the first operational amplifier. The positive terminal of the third diode V3 is located between the inverting input and the fourteenth resistor R14, and the negative terminal of the third diode V3 is located between the non-inverting input and the thirteenth resistor R13. The output of the first operational amplifier is connected to an AD conversion circuit, which is also connected to a processor.

[0012] According to one specific implementation of the embodiments of this application, the first analog switch or the second analog switch is configured as a single-pole double-throw switch.

[0013] Beneficial effects: The weak speed signal measurement system for aero-engines in this embodiment integrates a weak speed signal detection module, a load detection module, and a self-testing module. This enables precise capture of weak speed signals in complex environments, while simultaneously achieving online load detection and self-testing. Regarding weak speed signal detection, accurate acquisition of weak signals is ensured, and the load detection module accurately determines the status of the external speed sensor. The self-testing module, through a speed simulation excitation circuit and a channel switching circuit, achieves self-testing of the system, improving the reliability and adaptability of the measurement system. The system design fully considers the complexity and variability of the aero-engine operating environment, effectively addressing the effects of electromagnetic interference, mechanical vibration, environmental noise, load fluctuations, and temperature changes. It provides accurate and reliable speed signals for aero-engine control, fault diagnosis, and performance monitoring, significantly improving the reliability and adaptability of the measurement system and providing crucial support for the intelligent control and safe operation of aero-engines. Attached Figure Description

[0014] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic block diagram of a weak speed signal measurement system for an aero-engine according to an embodiment of the present invention. Figure 2 This is a schematic diagram of the winding self-test module according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the load detection module according to an embodiment of the present invention; Figure 4 This is a schematic diagram of a weak rotation speed signal detection module according to an embodiment of the present invention; Figure 5 This is a diagram showing the relationship between the output square wave and the input waveform of a hysteresis comparator circuit according to an embodiment of the present invention. Detailed Implementation

[0016] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0017] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0018] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0019] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The illustrations only show the components related to this application and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0020] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.

[0021] This application provides a weak speed signal measurement system for an aero-engine, as described below. Figures 1 to 5 Provide a detailed description.

[0022] In one embodiment, refer to Figure 1 The weak speed signal measurement system for aero-engines includes a weak speed signal detection module, a load detection module, a self-testing loop module, and a processor. The self-testing loop module includes a speed simulation excitation circuit and a channel switching circuit. The load detection module includes a load excitation circuit and a load excitation retrieval circuit. The input of the speed simulation excitation circuit is connected to the output of the processor, and the output of the speed simulation excitation circuit is connected to the input of the channel switching circuit. The input of the channel switching circuit is also connected to an external speed sensor and the output of the processor. The output of the channel switching circuit is connected to the input of the weak speed signal detection module, and the output of the weak speed signal detection module is connected to the input of the processor. The input of the load excitation circuit is connected to the output of the processor, and the output of the load excitation retrieval circuit is connected to the speed sensor. The input of the load excitation retrieval circuit is connected to the speed sensor, and the output of the load excitation retrieval circuit is connected to the input of the processor. The speed simulation excitation circuit receives control commands from the processor and generates an analog signal with the same voltage waveform as the external speed sensor. The signal frequency and voltage amplitude can be controlled by the program. At the same time, the processor sends a control signal to enable the control channel switching circuit to switch the analog signal into the weak speed signal acquisition module. The processor performs frequency acquisition and compares it with the frequency source value generated by the external speed sensor to complete the self-test function. The load excitation circuit receives control commands from the processor and generates an excitation voltage. After passing through the external speed sensor, the load excitation feedback circuit acquires the voltage and determines the status of the external speed sensor by the feedback voltage value.

[0023] In this embodiment, the load detection module also exhibits excellent performance. The coordinated operation of the load excitation circuit and the load excitation sampling circuit enables real-time and accurate determination of the external speed sensor's status. The load excitation circuit generates an excitation voltage, which, after passing through the speed sensor, is sampled by the load excitation sampling circuit. This closed-loop detection method acts like a comprehensive test of the speed sensor, promptly identifying potential faults or anomalies and providing strong support for stable system operation. The self-test module provides dual assurance for system reliability. The speed simulation excitation circuit generates an analog signal with the same voltage waveform as the external speed sensor, and both the signal frequency and voltage amplitude can be controlled by the program, allowing the analog signal to highly simulate the real speed signal. Under the processor's control, the channel switching circuit can flexibly switch the analog signal to the weak speed signal acquisition module, realizing the system's self-test function. By comparing the frequency of the acquired analog signal with the frequency source value generated by the external speed sensor, it is possible to quickly and accurately determine whether the system is working properly. If the difference exceeds a threshold, it indicates a potential system fault, requiring timely inspection and maintenance. This self-detection mechanism can detect problems early in the course of a fault, preventing the fault from escalating further and improving the reliability and stability of the system.

[0024] Furthermore, the system's overall design fully considers the complexity and variability of the aero-engine operating environment. It can effectively cope with the influence of various factors such as electromagnetic interference, mechanical vibration, environmental noise, load fluctuations, and temperature changes. This enables the system to operate reliably in various complex aero-engine operating environments, providing accurate and reliable speed signals for aero-engine control, fault diagnosis, and performance monitoring, and providing solid support for the intelligent control and safe operation of aero-engines. In one embodiment, refer to Figure 2 A second-order active filter circuit is provided between the speed simulation excitation circuit and the channel switching circuit, and a speed signal conditioning circuit can be set at the back end of the channel switching circuit.

[0025] Furthermore, the speed simulation excitation circuit is set as a DAC, and the channel switching circuit includes a first analog switch. During the self-test, the processor first issues a control command to switch the first analog switch circuit to the self-test channel. Then, the processor generates a control signal, and the DAC outputs a sine wave of the simulated speed signal. The amplitude and frequency can be configured according to the different sensor characteristics. After filtering out high-frequency interference by a second-order active filter circuit, the signal enters the speed signal conditioning circuit. Finally, the processor acquires the simulated speed frequency. If the absolute error between the frequency acquisition value of the external sensor and the generated frequency source value (simulated speed signal, not the external signal) is within the allowable range, the self-test passes. At the same time, the first analog switch switches to the external acquisition channel, begins to acquire the signal from the external sensor, and the processor reports that the circuit self-test is normal. Otherwise, the processor reports a circuit self-test fault.

[0026] In this embodiment, the first analog switch allows for flexible switching of signal paths, enabling the analog signal generated by the speed simulation excitation circuit or the signal from an external speed sensor to be input into the subsequent weak speed signal detection module. When a self-test is required, the first analog switch, under the control of the processor, switches the analog signal into the weak speed signal acquisition module, realizing the system's self-test function. When the external speed sensor signal is being acquired normally, the first analog switch can then input the external signal into the detection module, ensuring the system acquires the true speed signal. This flexible signal switching function allows the system to switch quickly and accurately between different operating modes, improving the system's adaptability and reliability. Simultaneously, the second-order active filter circuit further filters out interference and noise in the analog signal, improving signal quality and making the analog signal closer to the true speed signal, thereby improving the accuracy of the self-test. The speed signal conditioning circuit further processes and optimizes the signal after channel switching, such as amplification and shaping, ensuring that the signal input to the weak speed signal detection module meets the detection requirements, providing a strong guarantee for the system to accurately capture weak speed signals. Furthermore, the use of the first analog switch offers advantages such as low power consumption, high speed, and high reliability. Low power consumption means the system consumes less energy during operation, which helps extend the system's lifespan and reduce operating costs; high-speed switching capability ensures rapid switching between different operating modes, improving system response speed; and high reliability ensures the stability and accuracy of signal switching during long-term operation, reducing system errors and malfunctions caused by signal switching failures. In one embodiment, refer to Figure 3The load detection module includes a second analog switch, a first operational amplifier, an AD conversion circuit, multiple resistors, multiple capacitors, and a third diode V3. The second analog switch is connected to the processor's output, the twelfth resistor R12, and the speed sensor. The other end of the twelfth resistor R12 is connected to a 15V voltage. The non-inverting input of the first operational amplifier is connected to one end of the speed sensor through the thirteenth resistor R13, and the inverting input of the first operational amplifier is connected to the other end of the speed sensor through the fourteenth resistor R14. The fourteenth resistor R14 and the speed sensor are grounded through the fifteenth resistor R15. The non-inverting input of the first operational amplifier... The inverting input terminal of the first operational amplifier is grounded through the sixth capacitor C6, which is connected to the thirteenth resistor R13. The inverting input terminal of the first operational amplifier is grounded through the seventh capacitor C7, which is connected to the fourteenth resistor R14. A third diode V3 and a resistor Rg are connected in parallel between the inverting input terminal and the non-inverting input terminal of the first operational amplifier. The positive terminal of the third diode V3 is located between the inverting input terminal and the fourteenth resistor R14, and the negative terminal of the third diode V3 is located between the non-inverting input terminal and the thirteenth resistor R13. The output terminal of the first operational amplifier is connected to the AD conversion circuit, which is also connected to the processor.

[0027] In this embodiment, when load detection is performed, the processor issues a control command to close the second analog switch, inputting the excitation voltage to the speed sensor. The speed sensor is equivalent to a fixed resistor. By collecting the voltage across the sensor, the sensor's state is determined. The specific criteria are as follows: when the collected voltage is close to 0V, the external sensor is determined to be short-circuited; when the collected voltage is close to the ADC full-scale bias value of 10V, the external sensor is determined to be open-circuited; when the collected voltage matches the theoretical design value, the external sensor is determined to be online normally.

[0028] In this embodiment, the load detection module enables precise judgment of the external speed sensor's status. The closing and opening of the second analog switch, controlled precisely by the processor, flexibly inputs the excitation voltage to the speed sensor, providing a foundation for subsequent detection. The first operational amplifier amplifies the voltage signal across the speed sensor, allowing weak voltage signals to be acquired and analyzed more clearly and accurately. The AD conversion circuit converts the analog voltage signal into a digital signal, facilitating processing and judgment by the processor. A circuit composed of multiple resistors and capacitors serves to stabilize the signal and filter it. For example, resistors R13 (thirteenth), R14 (fourteenth), and R15 (fifteenth), in conjunction with capacitors, adjust circuit parameters to ensure the stability and accuracy of the voltage signal during transmission and processing. The third diode, V3, provides protection and limits the amplitude, preventing excessive voltage signals from damaging the circuit.

[0029] This load detection method, based on voltage acquisition and criterion judgment, boasts high reliability and accuracy. It can promptly detect faults such as short circuits and open circuits in external speed sensors, preventing measurement errors and system failures caused by sensor malfunctions. Simultaneously, for sensors operating normally online, accurate voltage acquisition and comparison ensure their stable and reliable operation.

[0030] Furthermore, the first analog switch or the second analog switch is configured as a single-pole double-throw switch.

[0031] In one embodiment, refer to Figure 4 The weak signal detection module includes a filter clamping circuit, a signal amplification circuit, and a hysteresis comparator circuit connected in sequence. The filter clamping circuit includes a first-order passive low-pass filter circuit, a first-order passive high-pass filter circuit, and a clamping circuit. The first-order passive low-pass filter circuit and the first-order passive high-pass filter circuit are used to filter out high-frequency interference and DC components in the speed signal. The clamping circuit is used to limit the amplitude of the speed signal. The signal amplification circuit is used to amplify the amplitude of the speed signal. The hysteresis comparator circuit is used to convert the amplified speed signal into a square wave of the same frequency.

[0032] Furthermore, the weak signal detection module includes a second operational amplifier, multiple resistors, multiple capacitors, and multiple diodes. A fifth capacitor C5 and a first diode V1 and a second diode V2 configured in reverse are connected in parallel between the non-inverting and inverting input terminals of the second operational amplifier. The non-inverting input terminal of the second operational amplifier is also connected to one end of the speed sensor through a third capacitor C3 and a first resistor R1. The third capacitor C3 and the first resistor R1 are grounded through the first capacitor C1. The connection point between the non-inverting input terminal of the second operational amplifier and the positive terminal of the first diode V1 is grounded to the third capacitor C3 through the third resistor R3. The inverting input terminal of the second operational amplifier is also connected to the other end of the speed sensor through a fourth capacitor C4 and a second resistor R2. The fourth capacitor C4... The second resistor R2 is grounded through the second capacitor C2. The connection point between the inverting input of the second operational amplifier and the negative terminal of the first diode V1 is grounded through the fourth capacitor C4 through the fourth resistor R4. The fifth resistor R5 is connected in parallel between the non-inverting input and output of the second operational amplifier. The output of the second operational amplifier is connected to a hysteresis comparator circuit. The first diode V1 and the second diode V2 form a clamping circuit. The first resistor R1, the second resistor R2, the first capacitor C1 and the second capacitor C2 form a first-order passive low-pass filter circuit. The third resistor R3, the fourth resistor R4, the third capacitor C3 and the fourth capacitor C4 form a first-order passive high-pass filter circuit. The fifth capacitor C5 is used for differential mode noise filtering. The second operational amplifier and the fifth resistor R5 form a signal amplification circuit.

[0033] Furthermore, the hysteresis comparator circuit includes a comparator and multiple resistors. The inverting input of the comparator is connected to the output of the second operational amplifier through the sixth resistor R6. The non-inverting input of the comparator is grounded through the eighth resistor R8 and the seventh resistor R7. The ninth resistor R9 is connected in parallel between the non-inverting input and the output of the comparator. The output of the comparator is connected to the processor through the eleventh resistor R11. The output of the comparator and the eleventh resistor R11 are grounded through the tenth resistor R10.

[0034] In practical implementation, the sensor input signal first passes through a bandpass filter circuit. Resistors R1 and R2, and capacitors C1 and C2 form a first-order passive low-pass filter circuit to filter out high-frequency noise in the signal and improve the module's anti-interference capability. Resistors R3 and R4, and capacitors C3 and C4 form a first-order passive high-pass filter circuit to filter out common-mode signals on the sinusoidal frequency signal. Before entering the amplifier, the frequency signal is limited by anti-parallel fast recovery diodes V1 and V2 to limit the amplitude of the speed signal input from the speed sensor within a certain voltage range, preventing damage to the downstream circuitry due to excessive input voltage. Capacitor C5 is used for differential-mode noise filtering. The clamped differential-mode frequency signal is then sent to instrumentation amplifier N1 for operational amplification to improve the signal-to-noise ratio. The gain of the instrumentation amplifier can be adjusted via resistor R5, and the gain can be configured according to the characteristics of the speed sensor signal. The amplified speed signal enters a hysteresis comparator circuit, primarily composed of comparator N2. Its core function is to convert the analog signal into a digital signal. By comparing the input signal with a threshold, it outputs a corresponding digital state. The high / low level toggling threshold of the digital signal can be adjusted via R7~R10 to prevent multiple transitions that may occur when the input signal approaches the threshold, ensuring the stability of the output signal. For the relationship between the input analog waveform and output digital waveform of the hysteresis comparator circuit and the high / low threshold voltages of the comparator circuit, please refer to [link to relevant documentation]. Figure 5 The converted digital signal can be acquired by a processor.

[0035] The embodiments provided by this invention, in terms of sensor status detection, utilize a load detection module and a circuit composed of a second analog switch, a first operational amplifier, and an AD conversion circuit. Based on voltage acquisition and criterion judgment, it can accurately determine faults such as short circuits and open circuits in the external speed sensor, ensuring the accuracy of sensor measurements and the stability of system operation. The self-test module, through a speed analog excitation circuit, a channel switching circuit, a second-order active filter circuit, and a speed signal conditioning circuit, realizes the system's self-test function, enabling early detection of problems and improving system reliability. In signal processing, the weak signal detection module is ingeniously designed. The first-order passive low-pass filter circuit, the first-order passive high-pass filter circuit, and the clamping circuit in the filter clamping circuit respectively filter out high-frequency interference and DC components from the speed signal and limit its amplitude; the signal amplification circuit effectively amplifies the signal amplitude; and the hysteresis comparator circuit converts the amplified analog signal into a stable square wave digital signal of the same frequency, facilitating processor acquisition and processing. The overall system design fully considers the complexity of the aero-engine operating environment and can effectively cope with various adverse factors such as electromagnetic interference and mechanical vibration. It provides accurate and reliable speed signals for aero-engine control, fault diagnosis and performance monitoring, and provides solid technical support for the intelligent control and safe operation of aero-engines. It has extremely high practical value and application prospects and can be widely used in various aero-engine speed measurement scenarios, promoting the development and progress of aero-engine related technologies.

[0036] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A system for measuring weak speed signals of an aero-engine, characterized in that, The system includes a weak speed signal detection module, a load detection module, a rewinding self-test module, and a processor. The rewinding self-test module includes a speed simulation excitation circuit and a channel switching circuit. The load detection module includes a load excitation circuit and a load excitation retrieval circuit. The input terminal of the speed simulation excitation circuit is connected to the output terminal of the processor, and the output terminal of the speed simulation excitation circuit is connected to the input terminal of the channel switching circuit. The input terminal of the channel switching circuit is also connected to an external speed sensor and the output terminal of the processor. The output terminal of the channel switching circuit is connected to the input terminal of the weak speed signal detection module, and the output terminal of the weak speed signal detection module is connected to the input terminal of the processor. The input terminal of the load excitation circuit is connected to the output terminal of the processor, and the output terminal of the load excitation retrieval circuit is connected to the speed sensor. The input terminal of the load excitation retrieval circuit is connected to the speed sensor, and the output terminal of the load excitation retrieval circuit is connected to the input terminal of the processor. The speed simulation excitation circuit receives the control command from the processor and generates an analog signal with the same voltage waveform as the external speed sensor. At the same time, the processor sends a control signal to enable the control channel switching circuit to switch the analog signal into the weak speed signal acquisition module. The processor performs frequency acquisition and compares it with the frequency source value generated by the external speed sensor to complete the rewind self-test function. The load excitation circuit receives the control command from the processor and generates an excitation voltage. After passing through the external speed sensor, the load excitation sampling circuit collects the voltage and determines the status of the external speed sensor by the sampled voltage value.

2. The aircraft engine weak speed signal measurement system according to claim 1, characterized in that, The weak signal detection module includes a filter clamping circuit, a signal amplification circuit, and a hysteresis comparator circuit connected in sequence. The filter clamping circuit includes a first-order passive low-pass filter circuit, a first-order passive high-pass filter circuit, and a clamping circuit. The first-order passive low-pass filter circuit and the first-order passive high-pass filter circuit are used to filter out high-frequency interference and DC components in the speed signal. The clamping circuit is used to limit the amplitude of the speed signal. The signal amplification circuit is used to amplify the amplitude of the speed signal. The hysteresis comparator circuit is used to convert the amplified speed signal into a square wave of the same frequency.

3. The aircraft engine weak speed signal measurement system according to claim 2, characterized in that, The weak signal detection module includes a second operational amplifier, multiple resistors, multiple capacitors, and multiple diodes. A fifth capacitor C5 and a first diode V1 and a second diode V2 configured in reverse are connected in parallel between the non-inverting and inverting inputs of the second operational amplifier. The non-inverting input of the second operational amplifier is also connected to one end of the speed sensor through a third capacitor C3 and a first resistor R1. The third capacitor C3 and the first resistor R1 are grounded through the first capacitor C1. The connection point between the non-inverting input of the second operational amplifier and the positive terminal of the first diode V1 is grounded to the third capacitor C3 through the third resistor R3. The inverting input of the second operational amplifier is also connected to the other end of the speed sensor through a fourth capacitor C4 and a second resistor R2. Resistor R2 is grounded through the second capacitor C2. The connection point between the inverting input of the second operational amplifier and the negative terminal of the first diode V1 is grounded through the fourth capacitor C4 through the fourth resistor R4. The fifth resistor R5 is connected in parallel between the non-inverting input and output of the second operational amplifier. The output of the second operational amplifier is connected to a hysteresis comparator circuit. The first diode V1 and the second diode V2 form a clamping circuit. The first resistor R1, the second resistor R2, the first capacitor C1 and the second capacitor C2 form a first-order passive low-pass filter circuit. The third resistor R3, the fourth resistor R4, the third capacitor C3 and the fourth capacitor C4 form a first-order passive high-pass filter circuit. The fifth capacitor C5 is used for differential mode noise filtering. The second operational amplifier and the fifth resistor R5 form a signal amplification circuit.

4. The aircraft engine weak speed signal measurement system according to claim 3, characterized in that, The hysteresis comparator circuit includes a comparator and multiple resistors. The inverting input of the comparator is connected to the output of the second operational amplifier through the sixth resistor R6. The non-inverting input of the comparator is grounded through the eighth resistor R8 and the seventh resistor R7. The ninth resistor R9 is connected in parallel between the non-inverting input and the output of the comparator. The output of the comparator is connected to the processor through the eleventh resistor R11. The output of the comparator and the eleventh resistor R11 are grounded through the tenth resistor R10.

5. The aircraft engine weak speed signal measurement system according to claim 1, characterized in that, A second-order active filter circuit is provided between the speed simulation excitation circuit and the channel switching circuit.

6. The aircraft engine weak speed signal measurement system according to claim 1, characterized in that, The speed simulation excitation circuit is set as a DAC, and the channel switching circuit includes a first analog switch.

7. The aircraft engine weak speed signal measurement system according to claim 1, characterized in that, The load detection module includes a second analog switch, a first operational amplifier, an AD conversion circuit, multiple resistors, multiple capacitors, and a third diode V3. The second analog switch is connected to the processor's output, the twelfth resistor R12, and the speed sensor. The other end of the twelfth resistor R12 is connected to a 15V voltage. The non-inverting input of the first operational amplifier is connected to one end of the speed sensor through the thirteenth resistor R13, and the inverting input of the first operational amplifier is connected to the other end of the speed sensor through the fourteenth resistor R14. The fourteenth resistor R14 and the speed sensor are grounded through the fifteenth resistor R15. The non-inverting input of the first operational amplifier... The input terminal is grounded through the sixth capacitor C6 between the thirteenth resistor R13 and the first operational amplifier. The inverting input terminal of the first operational amplifier is grounded through the seventh capacitor C7 between the fourteenth resistor R14 and the first operational amplifier. A third diode V3 and a resistor Rg are connected in parallel between the inverting input terminal and the non-inverting input terminal of the first operational amplifier. The positive terminal of the third diode V3 is located between the inverting input terminal and the fourteenth resistor R14, and the negative terminal of the third diode V3 is located between the non-inverting input terminal and the thirteenth resistor R13. The output terminal of the first operational amplifier is connected to the AD conversion circuit, which is also connected to the processor.

8. The aircraft engine weak speed signal measurement system according to claim 6 or 7, characterized in that, The first or second analog switch is configured as a single-pole double-throw switch.

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