An electro-hydraulic servo valve fault monitoring system and method

Abstract

This invention provides an electro-hydraulic servo valve fault monitoring system and method. The system includes: a monitoring valve assembly, a two-stage electro-hydraulic servo valve, and a motor monitoring assembly. The two-stage electro-hydraulic servo valve includes: a working torque motor and its preamplifier stage, a detection torque motor and its preamplifier stage, and a spool valve amplification stage. The monitoring valve assembly includes: a valve core and valve sleeve assembly, and a compression centering spring. The valve sleeve of the monitoring valve core and valve sleeve assembly has small holes around its two ends for communicating the detection pressure of the pilot stage. The motor monitoring assembly includes: a monitoring resistor, a voltage monitor, and a monitoring computer. Through the integrated design of dynamic monitoring of the torque motor, the servo valve can be rapidly monitored under high-frequency vibration conditions.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic actuation product testing technology, specifically relating to an electro-hydraulic servo valve fault monitoring system and method. Background Technology

[0002] Electro-hydraulic servo valves are key control components in hydraulic actuation systems. They convert and amplify the electrical signals output by the controller into hydraulic control signals, which are then output to the actuator to achieve servo control. An electro-hydraulic servo valve mainly consists of a torque motor, a pilot stage (or pre-stage), and a spool valve amplification stage. The torque motor assembly includes a coil assembly, a permanent magnet, and an armature assembly. The working principle of the electro-hydraulic servo valve is as follows: the electrical signal output by the controller is conducted through the coil assembly and generates electromagnetic force through the action of the permanent magnet. This causes the armature assembly to rotate, producing a small displacement. This displacement is transmitted to the pilot stage, generating a pressure difference ΔP, which drives the valve core of the spool valve amplification stage to displace and output control flow.

[0003] Because servo valves have a compact internal structure, with component and assembly dimensions often at the micrometer level, any malfunctions such as component performance degradation or contamination by foreign matter during operation can cause abnormal pilot stage pressure, affecting the servo valve's performance and potentially leading to partial actuator malfunction. Traditional servo valve pilot stage pressure monitoring relies heavily on external pressure sensors, which suffer from poor real-time signal transmission and difficulty in capturing high-frequency pressure fluctuations. Furthermore, external sensors and circuit packaging increase the size and manufacturing cost of the actuation system.

[0004] Currently, in-depth research has been conducted on electro-hydraulic servo valves focusing on technologies such as high pressure, high gain, and rapid response. The significant performance improvements have placed higher demands on the stability of servo valves. Their operation may generate high-frequency vibrations, which can be caused by various factors including abnormal control signals (electromagnetic interference, power fluctuations, etc.), hydraulic system abnormalities (excessive pressure pulsation, cavitation, contamination by foreign matter, etc.), mechanical defects (abnormal motor air gap, structural stiffness mismatch, structural wear, etc.), and system resonance. High-frequency vibrations in servo valves can accelerate the wear of armature components, valve core and sleeve components, and seals. This can lead to reduced control accuracy and increased internal leakage, or even shorten product lifespan, causing sudden malfunctions and downtime, and compromising system safety and reliability. Summary of the Invention

[0005] This invention designs an electro-hydraulic servo valve fault monitoring system and method. By integrating the valve components, it achieves real-time detection and fault monitoring of the pilot stage pressure, thereby improving the reliability of the actuation system. By integrating the motor monitoring components, it achieves rapid monitoring of the servo valve under high-frequency vibration.

[0006] The first aspect of this invention provides an electro-hydraulic servo valve fault monitoring system, comprising: a monitoring valve assembly, a two-stage electro-hydraulic servo valve, and a motor monitoring assembly; wherein, The two-stage electro-hydraulic servo valve includes: a working torque motor and its preamplifier stage, a sensing torque motor and its preamplifier stage, and a spool valve amplification stage; The monitoring valve assembly includes: a valve core and valve sleeve assembly and a compression centering spring; the valve sleeve of the monitoring valve core and valve sleeve assembly has small holes around both ends for communicating the pilot stage detection pressure; the valve core of the monitoring valve assembly is used to move against the spring force in one end of the control chamber when the pressure difference between the two pilot stage detection pressures exceeds a threshold; when the valve core of the monitoring valve assembly moves to different ends, the valve core and valve sleeve open the oil circuit and send a hydraulic signal to the actuation system; the hydraulic signal is used to indicate a servo valve malfunction. The motor monitoring component includes: a first monitoring resistor, a second monitoring resistor, a first voltage monitor, a second voltage monitor, and a monitoring computer; The first monitoring resistor and the second monitoring resistor are connected in parallel with the two coils of the working torque motor, respectively; the first voltage monitor and the second voltage monitor are used to measure the voltage across the first monitoring resistor and the second monitoring resistor, respectively; The monitoring computer is connected to the first voltage monitor and the second voltage monitor. It is used to establish a mapping model between high-frequency jitter and electrical signal characteristics based on the dynamic voltage drop change on the monitoring resistor, combined with the correlation between the resistance temperature rise effect and the coil inductance parameters, so as to analyze and evaluate the jitter phenomenon.

[0007] Optionally, when the actuation system receives a hydraulic signal, it cuts off the high-pressure oil supply, the main servo motor disengages and reports a fault, and automatically switches to the standby servo motor.

[0008] Optionally, the monitoring computer is also used to feed back the voltage signals provided by the first voltage monitor and the second voltage monitor to the controller of the servo valve. The controller dynamically adjusts the PWM duty cycle or current amplitude of the drive signal according to the feedback signal to suppress the high-frequency fluctuation of the coil current I, and finally realizes the closed-loop damping control of the system.

[0009] Optionally, the control chambers at both ends of the valve core and valve sleeve assembly are connected to the detection chambers on both sides of the detection torque motor.

[0010] Optionally, the compression centering spring is arranged symmetrically relative to the detection valve core, with one side of the spring placed in the annular groove of the spring seat and the other side placed in the pressure plate annular groove that tops the detection valve core, and has a certain preload.

[0011] Optionally, the pressure plate is provided with a central hole for flow passage.

[0012] Optionally, the spring seat is connected to the inner hole of the valve sleeve and is provided with a threaded hole for end face fixing.

[0013] The second aspect of the present invention provides a method for monitoring faults in an electro-hydraulic servo valve, which is implemented using an electro-hydraulic servo valve fault monitoring system as described in any one of the first aspects.

[0014] The beneficial effects of this invention are as follows: The product structure of this invention is clear, and the performance is excellent. It proposes an electro-hydraulic servo valve fault monitoring system and method. The method is simple and effective. Through the design of the monitoring valve assembly, it achieves real-time monitoring of the pilot stage pressure and fault monitoring of the servo valve. Through the integrated design of dynamic monitoring of the torque motor, it achieves rapid monitoring of the servo valve under high-frequency vibration. This method overcomes the limitations of designing external sensors, simplifies the scale of the testing system, has a compact structure, reduces the volume of the actuation system, and can effectively support the high reliability, high safety, and stable operation of the product. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 A schematic diagram of a fault monitoring method for an electro-hydraulic servo valve; Explanation of reference numerals in the attached figures: 1-Working torque motor, 2-Monitoring torque motor, 3-Main valve core, 4-Valve body, 5-Pilot stage, 6-Monitoring valve sleeve, 7-Detection valve core, 8-Compression centering spring, 9-Spring seat, 10-Pressure plate, 11-First monitoring resistor, 12-Second monitoring resistor, 13-First voltage monitor, 14-Second voltage monitor, 15-Monitoring computer, 16-Controller. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0019] In the description of this invention, it should be noted that the directions or positional relationships indicated by terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" are based on the directions or positional relationships shown in the accompanying drawings and are only for the convenience of describing and simplifying the invention, and should not be construed as limiting the invention. Furthermore, the use of ordinal numbers (e.g., "first and second," etc.) is for distinguishing objects and is not limited to this order, and should not be construed as indicating or implying relative importance.

[0020] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly, encompassing both direct connection and indirect connection via an intermediate medium. Those skilled in the art can understand the specific meaning of these terms in this invention based on the specific circumstances.

[0021] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited in each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0023] like Figure 1 As shown, the present invention provides an electro-hydraulic servo valve fault monitoring system, which includes a monitoring valve assembly, a two-stage electro-hydraulic servo valve, a motor monitoring assembly, etc.

[0024] The two-stage electro-hydraulic servo valve includes a working torque motor 1 and its preamplifier stage, a monitoring torque motor 2 and its preamplifier stage, and a spool valve amplification stage, etc. The monitoring valve assembly includes a valve core and valve sleeve assembly, a compression centering spring 8, a spring seat 9, and a pressure plate 10; The motor monitoring components include a monitoring resistor, a voltage monitor, and a monitoring computer.

[0025] Inputting a control signal to the working torque motor can achieve the corresponding flow output. Inputting the same control signal to the monitoring torque motor, and monitoring the pressure difference in the detection chamber (pilot stage pressure) in real time through the monitoring valve assembly and comparing it with the threshold, can determine whether there is a fault in the actuation system. By analyzing the characteristic fluctuation of the monitoring resistor electrical signal through the motor monitoring assembly, the high-frequency jitter of the servo valve can be analyzed and evaluated.

[0026] In this invention, the pressure sensing and fault monitoring of the pilot stage of the servo valve are realized through the monitoring valve assembly, and the high-frequency jitter of the servo valve is monitored in real time through the motor monitoring assembly. The integrated design of the detection valve core 7 of the monitoring valve assembly with built-in compression centering springs 8 at both ends is used for pressure sensing. No additional sensors and circuits are required. The method is simple, effective, and compact. The redundant dual-spring design of the monitoring valve assembly in this invention, and its symmetrical arrangement, effectively suppresses oil pressure pulsation interference when the detection valve core is in the hydraulic zero position, and effectively realizes pilot stage pressure sensing. In this invention, the monitoring valve assembly can be integrated into the actuator housing, thereby reducing the size of the actuation system.

[0027] In this invention, the motor monitoring component uses a non-inductive design with parallel resistors, which does not affect the dynamic and static performance of the product, eliminates the need to introduce sensors to monitor current fluctuations, and avoids issues such as added weight and electromagnetic interference to the system. In this invention, the motor monitoring component utilizes the dynamic voltage drop change of the coil current across the parallel resistor, combined with the correlation between the resistance temperature rise effect and the coil inductance parameters, to establish a mapping model between high-frequency jitter and electrical signal characteristics, and to analyze and evaluate the jitter phenomenon. In this invention, the motor monitoring component uses a parallel resistor as both a current discharge path and a monitoring node, thereby integrating the dual functions of drive circuit protection and status monitoring and improving system reliability.

[0028] A schematic diagram of an electro-hydraulic servo valve fault monitoring system designed in this invention is shown below. Figure 1 As shown, taking the spray-type electro-hydraulic servo valve as an example, the monitoring system consists of a monitoring valve assembly, a motor monitoring assembly, etc.

[0029] The spray-baffle type electro-hydraulic servo valve consists of a working torque motor 1, a monitoring torque motor 2, a pilot stage 5 (nozzle-baffle amplification stage), a valve body 4, and a main valve core 3.

[0030] When a control signal is input, the working torque motor operates, and the pressure change in its pre-stage generates a pressure differential, causing the main valve core to move and the control window to open, achieving normal flow output. Simultaneously, the pre-stage of the detection torque motor generates a corresponding detection pressure differential ΔPm = |Pm1 - Pm2|. Whether a system fault exists can be reflected by ΔPm (typically, a ΔPm threshold is set; under normal system conditions, ΔPm should be less than the threshold).

[0031] The monitoring valve assembly includes: a monitoring valve core and sleeve assembly, a compression centering spring and its corresponding spring seat and pressure plate.

[0032] The monitoring valve core and sleeve assembly includes a monitoring valve sleeve 6 with a throttling window and a detection valve core 7 built into the inner hole of the valve sleeve. Small holes are provided around both ends of the valve sleeve to facilitate the communication of the pilot stage detection pressure. The compression centering spring is symmetrically arranged relative to the detection valve core. One side of the spring is placed in the annular groove of the spring seat, and the other side is placed in the annular groove of the pressure plate that presses against the detection valve core, and has a certain preload. The pressure plate is provided with a central hole for flow passage. The spring seat is connected to the inner hole of the valve sleeve and is provided with a threaded hole for end face fixing.

[0033] Specifically, the method for monitoring the pilot stage pressure of the electro-hydraulic servo valve is as follows: 1) Under normal operating conditions, the working torque motor and the monitoring torque motor of the servo valve work synchronously with very small consistency error. The oil pressure difference between the two ends of the valve core detected by the monitoring valve assembly is very small, lower than the preload of the compression centering spring, and the valve core is detected to be in the neutral position, and the actuation system is working normally. 2) When a fault occurs in a certain part of the actuation system, the synchronization error of the working torque motor and the monitoring torque motor increases, causing the oil pressure difference at both ends of the monitoring valve assembly to increase accordingly and exceed the preload of its compression centering spring. The detection valve core moves to one end, the corresponding window of the detection valve sleeve opens, the actuation system cuts off the high-pressure oil supply, the main servo motor stops working and reports a fault, and at the same time automatically switches to standby servo motor operation.

[0034] The motor monitoring component comprises a first monitoring resistor 11, a second monitoring resistor 12, a first voltage monitor 13, a second voltage monitor 14, and a monitoring computer. The resistance values ​​of the first monitoring resistor 11 and the second monitoring resistor 12 are denoted as R1 and R2, respectively. The voltages detected by the first voltage monitor 13 and the second voltage monitor 14 are denoted as V1 and V2, respectively.

[0035] Specifically, the high-frequency jitter monitoring method for the electro-hydraulic servo valve is as follows: 1) Test: Controller 16 generates a drive signal, and the servo valve coil operating current... IAs the drive signal changes, the resistance values ​​of the first monitoring resistor 11 and the second monitoring resistor 12 connected in parallel are much smaller than the coil impedance. Under high-frequency signals, the current mainly flows through the first monitoring resistor 11 and the second monitoring resistor 12, forming a voltage divider monitoring branch, resulting in a monitoring voltage V1. I ×R1、V2= I ×R2; The monitoring resistor should be a high-precision resistor with low inductance and low temperature drift. By balancing the monitoring signal strength and the impact on the system, the resistance value is generally selected to be around 1 to 2 ohms.

[0036] Servo valve control is a current-loop closed-loop control system. When a parallel resistor is present, the controller will compensate for the current diverted by the parallel branch by increasing the output voltage to ensure the accuracy of the control current of the servo valve coil. If a parallel resistor is not used and the current of the coil assembly is directly monitored by a voltmeter, the voltmeter will monitor the superposition of the voltage corresponding to the drive current and the back EMF due to the influence of the back EMF in the coil, which cannot reflect the actual drive current.

[0037] 2) Monitoring: When the coil current I When stable, the voltages V1 and V2 across the first monitoring resistor 11 and the second monitoring resistor 12 are stable DC outputs. When the servo valve experiences high-frequency jitter, the voltages V1 and V2 across the first monitoring resistor 11 and the second monitoring resistor 12 exhibit periodic fluctuations, and the amplitude is positively correlated with the jitter intensity. This test system avoids the added weight of the product and electromagnetic interference issues by not introducing sensors to monitor current fluctuations. Furthermore, the first monitoring resistor 11 and the second monitoring resistor 12 can serve as current discharge paths and monitoring nodes, achieving integrated protection and status monitoring of the drive circuit, thus improving system reliability. 3) Analysis: The voltage signals V1 and V2 across the first monitoring resistor 11 and the second monitoring resistor 12 are fed back to the monitoring computer 15. The monitoring computer 15 analyzes the voltage signals and analyzes the high-frequency jitter frequency and jitter amplitude of the servo valve. In addition, the system can use the dynamic voltage drop change of the coil current across the parallel resistor, combined with the correlation between the resistance temperature rise effect and the coil inductance parameters, to establish a mapping model between high-frequency jitter and electrical signal characteristics, and perform analysis and evaluation of jitter phenomena. 4) Control: The monitoring computer outputs feedback signals to the controller, dynamically adjusting the PWM duty cycle or current amplitude of the drive signal based on the feedback signals to suppress coil current. I The high-frequency fluctuations are ultimately controlled by achieving closed-loop damping control of the system, reducing the degree and probability of high-frequency jitter in the servo valve.

[0038] The above detailed embodiments are a description of the present invention. It should not be considered that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the protection scope of the present invention.

Claims

1. A fault monitoring system for an electro-hydraulic servo valve, characterized in that, include: Monitoring valve assembly, two-stage electro-hydraulic servo valve, motor monitoring assembly; among which, The two-stage electro-hydraulic servo valve includes: a working torque motor and its preamplifier stage, a sensing torque motor and its preamplifier stage, and a spool valve amplification stage; The monitoring valve assembly includes: a valve core and valve sleeve assembly and a compression centering spring; the valve sleeve of the valve core and valve sleeve assembly has small holes around its two ends for communicating the pilot stage detection pressure; the valve core of the monitoring valve assembly is used to move against the spring force in one end control chamber when the pressure difference between the two pilot stage detection pressures exceeds a threshold; when the valve core of the monitoring valve assembly moves to different ends, the valve core and valve sleeve open the oil circuit and send a hydraulic signal to the actuation system; the hydraulic signal is used to indicate a servo valve malfunction; the two end control chambers of the valve core and valve sleeve assembly are connected to the two detection chambers of the detection torque motor; The motor monitoring component includes: a first monitoring resistor, a second monitoring resistor, a first voltage monitor, a second voltage monitor, and a monitoring computer; The first monitoring resistor and the second monitoring resistor are connected in parallel with the two coils of the working torque motor, respectively; the first voltage monitor and the second voltage monitor are used to measure the voltage across the first monitoring resistor and the second monitoring resistor, respectively; The monitoring computer is connected to the first voltage monitor and the second voltage monitor. It is used to establish a mapping model between high-frequency jitter and electrical signal characteristics based on the dynamic voltage drop change on the monitoring resistor, combined with the correlation between the resistance temperature rise effect and the coil inductance parameters, so as to analyze and evaluate the jitter phenomenon.

2. The electro-hydraulic servo valve fault monitoring system according to claim 1, characterized in that, When the actuation system receives a hydraulic signal, it cuts off the high-pressure oil supply, the main servo motor disengages and reports a fault, and at the same time automatically switches to the standby servo motor.

3. The electro-hydraulic servo valve fault monitoring system according to claim 1, characterized in that, The monitoring computer is also used to feed back the voltage signals provided by the first voltage monitor and the second voltage monitor to the controller of the servo valve. The controller dynamically adjusts the PWM duty cycle or current amplitude of the drive signal according to the feedback signal to suppress the high-frequency fluctuation of the coil current I, and finally realizes the closed-loop damping control of the system.

4. The electro-hydraulic servo valve fault monitoring system according to claim 1, characterized in that, The compression centering spring is arranged symmetrically relative to the detection valve core. One side of the spring is placed in the annular groove of the spring seat, and the other side is placed in the pressure plate annular groove that tops the detection valve core, and has a certain preload.

5. The electro-hydraulic servo valve fault monitoring system according to claim 4, characterized in that, The pressure plate is provided with a central hole for flow.

6. The electro-hydraulic servo valve fault monitoring system according to claim 5, characterized in that, The spring seat is connected to the inner hole of the valve sleeve and is provided with a threaded hole for end face fixing.

7. A method for monitoring faults in an electro-hydraulic servo valve, characterized in that, The fault monitoring system for electro-hydraulic servo valves as described in any one of claims 1-6 is adopted.

Images