A self-sensing hydraulic valve body integrating PVDF piezoelectric film and its control method

Abstract

This invention relates to the field of fluid pressure system components, and particularly to a self-sensing hydraulic valve body and control method integrating a PVDF piezoelectric film. The valve body includes a sensing unit, an integrated valve body housing assembly, and a top cover. The sensing unit is based on a support ring with three stepped layers, and is equipped with three layers of PVDF piezoelectric film and corresponding silicone to form a three-level sensing. The housing assembly is connected to the hydraulic valve body via a cylindrical thread, and features a liquid flow channel and a double seal of PDMS film and O-ring. The control method relies on the PVDF piezoelectric effect for self-powered operation. Hydraulic pressure triggers the PVDF film to output signals in stages. The amplitude, frequency, and other characteristics of the electrical signal are extracted and compared with preset thresholds to determine anomalies, and feedback is used to regulate the valve body to achieve closed-loop control. This invention achieves integrated miniaturization, low power consumption, improved detection accuracy and oil contamination resistance, and can monitor and control the system in real time with a closed loop.

Description

Technical Field

[0001] This invention relates to the field of fluid pressure system components, and in particular to a self-sensing hydraulic valve body and control method integrating a PVDF piezoelectric film. Background Technology

[0002] In hydraulic systems, pressure monitoring is a crucial element in ensuring safe and stable operation. This is especially true in the field of micro hydraulic equipment, where the limitations of traditional hydraulic sensors become increasingly apparent due to the limited installation space at key monitoring points such as branch oil circuits and valve body pressure test ports.

[0003] Traditional hydraulic sensors have the following drawbacks: First, they are large in size, making them difficult to install in space-constrained environments such as micro-devices; second, they rely on external power supply modules, which increases the complexity of system wiring and power consumption; third, the signals are easily affected by oil contamination in the hydraulic system and electromagnetic interference, leading to a decrease in detection accuracy; and fourth, when the pressure range is wide, they are prone to insufficient sensitivity in the low-pressure range or signal saturation in the high-pressure range, making it difficult to accurately monitor a wide range of pressures.

[0004] These problems limit the application of traditional sensors in micro hydraulic equipment, thus creating an urgent need for a miniaturized, self-powered, interference-resistant, and high-precision hydraulic pressure sensor. Summary of the Invention

[0005] To overcome the shortcomings of traditional hydraulic sensors in the prior art, such as large size, reliance on external power supply, susceptibility to signal interference, and poor adaptability in micro-devices, this invention provides a self-sensing hydraulic valve body and control method integrating a PVDF piezoelectric film.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A self-sensing hydraulic valve body with integrated PVDF piezoelectric film includes: a sensing unit, a valve body integrated housing assembly, and a top cover;

[0008] The sensing unit is disposed inside the valve body integrated housing assembly and is pressed against the top cover;

[0009] The sensing unit includes a stepped support ring, several layers of circular PVDF piezoelectric films, and several layers of silicone. Several steps are provided on the stepped support ring, and the several layers of silicone are placed on the corresponding steps. The circular PVDF piezoelectric films are attached to the corresponding silicone bottom surfaces.

[0010] The valve body integrated housing assembly includes a housing, an O-ring seal, and an oil-separating PDMS (polydimethylsiloxane) film; the housing has an inner cavity, the upper half of the inner cavity is provided with an internal thread, the bottom of the housing is provided with a cylindrical thread, and a liquid flow channel is provided at the center of the cylindrical thread;

[0011] The O-ring is installed at the cylindrical thread at the bottom of the housing; the oil-separating PDMS film is disposed at the bottom of the inner cavity of the housing and covers the liquid flow channel for contact with the liquid entering the liquid flow channel;

[0012] The top cover is provided with an external thread, which is connected to the internal thread of the outer shell to fix the sensing unit in the inner cavity of the outer shell.

[0013] Furthermore, the stepped support ring is provided with three steps, and the silicone includes bottom silicone, middle silicone, and top silicone; the number of circular PVDF piezoelectric films is three, which are respectively attached to the bottom surface of the bottom silicone, middle silicone, and top silicone; the bottom silicone and its bottom circular PVDF piezoelectric film are placed on the first step of the stepped support ring, and the bottom circular PVDF piezoelectric film of the bottom silicone is in contact with the oil-separating PDMS film; the middle silicone and its bottom circular PVDF piezoelectric film are placed on the second step of the stepped support ring; the top silicone and its bottom circular PVDF piezoelectric film are placed on the third step of the stepped support ring and are pressed tightly by the top cap.

[0014] Furthermore, a wiring groove is provided on the side of the stepped support ring, and a wiring hole is provided on one side of the housing; the output signal line of the circular PVDF piezoelectric film is converged through the wiring groove and led out to the outside of the housing through the wiring hole.

[0015] Furthermore, the top end face of the top cover is provided with an internal hexagonal hole.

[0016] This invention also provides a self-powered hydraulic pressure sensor control method, applied to the aforementioned self-sensing hydraulic valve body with integrated PVDF piezoelectric film, the method comprising the following steps:

[0017] S1: Receives electrical signals generated by each layer of circular PVDF piezoelectric film in the sensing unit;

[0018] S2: Determine the current hydraulic pressure state based on the received electrical signal; wherein, when the liquid pressure is low, only the bottom circular PVDF piezoelectric film generates an electrical signal; when the liquid pressure increases to a first preset level, the bottom silicone is deformed by pressure and squeezed outward, triggering the middle circular PVDF piezoelectric film to generate an electrical signal; when the liquid pressure continues to increase to a second preset level, the middle silicone is deformed by pressure and squeezed outward, triggering the top circular PVDF piezoelectric film to generate an electrical signal;

[0019] S3: Extract the characteristic parameters of the electrical signal, including amplitude, frequency and waveform distortion rate;

[0020] S4: Compare and analyze the extracted feature parameters with preset thresholds to determine whether there are abnormal operating conditions in the hydraulic circuit. The abnormal operating conditions include leakage faults, component wear, oil circuit blockage, or seal failure.

[0021] S5: Generates control commands based on the judgment results and feeds them back to the control module of the hydraulic valve body to perform regulation operations on the hydraulic valve body, thereby realizing closed-loop control.

[0022] The beneficial effects of this invention are:

[0023] This system achieves miniaturization and integration of the sensor, making it suitable for space-constrained scenarios in micro hydraulic equipment. Utilizing the piezoelectric effect of PVDF, it achieves self-powered operation, eliminating the need for an external power supply module and reducing power consumption. A three-stage stepped sensing structure resolves the accuracy conflict between high and low pressure ranges, improving the accuracy of pressure detection over a wide range. A dual-sealing structure using O-rings and an oil-separating PDMS membrane enhances resistance to oil contamination interference, ensuring monitoring stability. Combined with signal characteristic analysis and closed-loop control, it enables real-time diagnosis and adjustment of system faults. Attached Figure Description

[0024] Figure 1 This is an exploded view of a hydraulic pressure sensor provided in an embodiment of the present invention;

[0025] Figure 2 This is a cross-sectional schematic diagram of the sensing unit in an embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of the stepped support ring in an embodiment of the present invention;

[0027] Figure 4 This is a cross-sectional schematic diagram of the outer casing in an embodiment of the present invention;

[0028] Figure 5 This is a schematic diagram of the top cover in an embodiment of the present invention;

[0029] Figure 6 This is a schematic diagram illustrating the working principle of the sensing part in an embodiment of the present invention;

[0030] Figure 7 This is a flowchart illustrating the closed-loop control process according to an embodiment of the present invention.

[0031] Figure 8 This is a flowchart illustrating the process of an embodiment of the present invention.

[0032] In the picture,

[0033] 1-Sensing unit; 11-Stepped support ring; 111-Step; 112-Wire routing channel; 12-Circular PVDF piezoelectric film; 13-Bottom silicone; 14-Middle silicone; 15-Top silicone;

[0034] 2-Valve body integrated housing assembly; 21-Housing; 211-Housing cavity; 212-Internal thread; 213-Pinner thread; 214-Liquid flow channel; 215-Wire routing hole; 22-O-ring seal; 23-Oil-separating PDMS membrane;

[0035] 3-Top cap; 31-Internal hexagonal hole; 32-External thread. Detailed Implementation

[0036] 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 a part of the embodiments of the present invention, and not all of them. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0037] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0038] Figures 1-8 In one specific embodiment of the present invention, a self-sensing hydraulic valve body integrating a PVDF piezoelectric film is provided, which mainly consists of a sensing unit 1, a valve body integrated housing assembly 2, and a top cover 3.

[0039] The sensing unit 1 is assembled in the inner cavity 211 of the housing 21. It is tightened and fixed by the external thread 32 of the top cover 3 and the internal thread 212 of the inner cavity, forming an axial preload to ensure that all components fit tightly. The cylindrical thread 213 at the bottom of the housing 21 is used to connect with the hydraulic valve body. The liquid flow channel 214 at the center of the cylindrical thread introduces hydraulic oil, which acts directly on the oil-separating PDMS membrane 23. The wiring hole 215 on one side of the housing cooperates with the wiring groove 112 of the stepped support ring 11 to form a signal wire outlet channel. An internal hexagonal hole 31 is provided on the top cover 3 for easy tool installation and removal.

[0040] The sensing unit 1 is the core sensing component, consisting of a stepped support ring 11, three layers of circular PVDF piezoelectric films 12, and corresponding bottom silicone 13, middle silicone 14, and top silicone 15. The stepped support ring 11 has three steps 111 with increasing diameters, which respectively fit the bottom silicone 13, middle silicone 14, and top silicone 15.

[0041] A first circular PVDF piezoelectric film 12 is adhered to the lower surface of the bottom silicone 13. A conductive silver paste is coated in the middle layer of this film to output electrical signals. During operation, it is in direct contact with the oil-separating PDMS film 23. A second circular PVDF piezoelectric film 12 is adhered to the lower surface of the middle silicone 14. A third circular PVDF piezoelectric film 12 is adhered to the lower surface of the top silicone 15. The electrode leads of the three films converge through the wiring groove 112 and are then led out through the wiring hole 215 in the outer casing.

[0042] The working principle and control method of this embodiment are described below.

[0043] like Figure 6 As shown, during operation, hydraulic oil acts on the oil-separating PDMS film 23 through the liquid flow channel 214. The film deforms and squeezes the bottom silicone 13, causing the first circular PVDF piezoelectric film 12 to bear mechanical stress. Based on the piezoelectric effect, the film outputs an electrical signal, and the signal amplitude changes linearly with the pressure.

[0044] When the pressure increases to a certain value, the bottom silicone 13 deforms and expands outward, pushing the middle silicone 14 to squeeze the second layer of circular PVDF piezoelectric film 12, triggering the second layer signal output, which is superimposed with the first layer signal. When the pressure continues to increase beyond the set value, the middle silicone 14 deforms further, driving the third layer of circular PVDF piezoelectric film 12 to work, and the three layers of signals are output in synergy.

[0045] This hierarchical sensing mechanism ensures sensitivity in the low-voltage segment while solving the signal saturation problem in the high-voltage segment.

[0046] like Figure 7 and Figure 8 As shown, the control methods include:

[0047] 1. Signal acquisition: When the oil-separating PDMS film 23 is subjected to hydraulic pressure, it transmits the first layer of sensing signal to the circular PVDF piezoelectric film 12 at the bottom; as the pressure increases, the second and third layers of sensing signals are generated in sequence.

[0048] 2. Signal processing: The signal processor receives electrical signals from each layer of PVDF film and determines the current liquid pressure range and specific value by analyzing the changes in the electrical signals (such as amplitude superposition).

[0049] 3. Fault diagnosis: The signal processing module extracts the characteristic parameters (amplitude, frequency and waveform distortion rate) of the electrical signal, compares and analyzes the extracted characteristic parameters with preset thresholds, and determines whether there are abnormal working conditions such as leakage faults, component wear, oil circuit blockage or seal failure in the hydraulic oil circuit.

[0050] 4. Closed-loop control: The safety judgment result is fed back to the control module of the hydraulic valve body, and the control module performs regulation operations on the hydraulic valve body based on the result, thereby realizing closed-loop control of the hydraulic system.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A self-sensing hydraulic valve body integrating a PVDF piezoelectric film, comprising a sensing unit (1), a valve body integrated housing assembly (2), and a top cover (3), characterized in that: The sensing unit (1) is located inside the valve body integrated housing assembly (2) and is pressed by the top cover (3); The sensing unit (1) includes a stepped support ring (11), three circular PVDF piezoelectric films (12), and three layers of silicone. The stepped support ring (11) is provided with three steps (111), and the silicone is placed on the corresponding steps (111). The circular PVDF piezoelectric films (12) are attached to the bottom surface of the corresponding silicone. The valve body integrated housing assembly (2) includes a housing (21), an O-ring (22), and an oil-separating PDMS membrane (23); the housing (21) has an inner cavity (211), the upper half of the inner cavity (211) is provided with an internal thread (212), the bottom of the housing (21) is provided with a cylindrical thread (213), and a liquid flow channel (214) is provided at the center of the cylindrical thread (213); the O-ring (22) is installed at the cylindrical thread (213) at the bottom of the housing (21); the oil-separating PDMS membrane (23) is provided at the bottom of the inner cavity (211) and covers the liquid flow channel (214) for contact with the liquid entering the liquid flow channel (214); the O-ring (22) and the oil-separating PDMS membrane (23) form a double sealing structure; The top cover (3) is provided with an external thread, which is connected to the internal thread (212) of the outer shell (21) to fix the sensing unit (1) in the inner cavity (211) of the outer shell; The silicone includes bottom silicone (13), middle silicone (14) and top silicone (15); The number of the circular PVDF piezoelectric films (12) is three, which are respectively attached to the bottom surface of the bottom silicone (13), the middle silicone (14) and the top silicone (15); The bottom silicone (13) and its bottom circular PVDF piezoelectric film (12) are placed on the first step of the stepped support ring (11), and the bottom circular PVDF piezoelectric film (12) of the bottom silicone (13) is in contact with the oil-separating PDMS film (23). The central silicone (14) and its bottom circular PVDF piezoelectric film (12) are placed on the second step of the stepped support ring (11); The top silicone (15) and the circular PVDF piezoelectric film (12) on its bottom surface are placed on the third step of the stepped support ring (11) and pressed by the top cover (3).

2. The self-sensing hydraulic valve body with integrated PVDF piezoelectric film according to claim 1, characterized in that: The stepped support ring (11) has a wiring groove (112) on its side, and the outer shell (21) has a wiring hole (215) on one side. The output signal line of the circular PVDF piezoelectric film (12) is converged through the wiring groove (112) and led out to the outside of the outer shell (21) through the wiring hole (215).

3. The self-sensing hydraulic valve body with integrated PVDF piezoelectric film according to claim 1, characterized in that: The top end face of the top cap (3) is provided with an internal hexagonal hole (31).

4. A self-powered hydraulic pressure sensor control method, applied to a self-sensing hydraulic valve body with an integrated PVDF piezoelectric film as described in any one of claims 1-3, characterized in that, Includes the following steps: S1, receives electrical signals generated by each layer of circular PVDF piezoelectric film (12) in the sensing unit (1); S2, determine the current hydraulic pressure status based on the received electrical signal; When the liquid pressure is low, only the bottom circular PVDF piezoelectric film (12) generates an electrical signal; when the liquid pressure increases to the first preset level, the bottom silicone (13) is deformed by pressure and squeezed outward, triggering the middle circular PVDF piezoelectric film (12) to generate an electrical signal; when the liquid pressure continues to increase to the second preset level, the middle silicone (14) is deformed by pressure and squeezed outward, triggering the top circular PVDF piezoelectric film (12) to generate an electrical signal. S3, extract the characteristic parameters of the electrical signal, including amplitude, frequency and waveform distortion rate; S4. The extracted feature parameters are compared and analyzed with preset thresholds to determine whether there are abnormal operating conditions in the hydraulic circuit. The abnormal operating conditions include leakage faults, component wear, oil circuit blockage or seal failure. S5 generates control commands based on the judgment results and feeds them back to the control module of the hydraulic valve body to perform regulation operations on the hydraulic valve body, thereby realizing closed-loop control.

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