A piezoelectric adjustable cavity plunger pump outlet pulsation suppression device

Abstract

This invention discloses a piezoelectric adjustable-cavity plunger pump outlet pulsation suppression device, comprising an oil outlet pipe and several resonance absorbers. The oil outlet pipe is fixed at the oil outlet of the plunger pump; several resonance absorbers are spaced apart along the axial direction of the oil outlet pipe. Each resonance absorber includes a housing, a piezoelectric diaphragm, a piston mechanism, and a controller; the piezoelectric diaphragm is sealed to the inner wall of the housing, dividing the housing into an oil chamber and a resonance chamber; the oil chamber is located on the side of the piezoelectric diaphragm facing the oil outlet pipe and is in sealed communication with the oil outlet pipe; the piezoelectric diaphragm outputs a voltage signal in real time after sensing oil pulsation; the piston mechanism is located on the side of the resonance chamber away from the piezoelectric diaphragm, and a sealed air zone is constructed between the piston mechanism and the piezoelectric diaphragm; the volume of the air zone is adjustable to generate vibration at the same frequency as the oil pulsation; the controller processes the voltage signal from the piezoelectric diaphragm to calculate the oil pulsation frequency, and then outputs a control signal to the piston mechanism according to the pulsation frequency to control the latter to adjust the volume of the air zone.

Description

Technical Field

[0001] This invention relates to the field of hydraulic pulsation suppression technology, and in particular to a piezoelectric adjustable cavity plunger pump outlet pulsation suppression device. Background Technology

[0002] Hydraulic systems are widely used in fields such as engineering machinery and aerospace, with axial piston pumps being one of the most commonly used hydraulic power components. However, due to the reciprocating motion characteristics of piston pumps during operation, the output oil pressure and flow rate will fluctuate periodically, forming oil pulsation. This pulsation not only causes system vibration and noise but also reduces the system's working accuracy, shortens equipment lifespan, and seriously affects the overall performance of the hydraulic system.

[0003] Currently, the main methods for suppressing oil pulsation fall into two categories: passive and active. Passive suppression devices mainly include expansion chambers and accumulators. Although their structure is simple, their resonant frequency is fixed, making it difficult to adapt to changes in pulsation frequency under different operating conditions, resulting in limited suppression effectiveness. Active suppression devices, while capable of dynamic adjustment, generally suffer from slow response speed, complex structure, and high cost. For example, the active control scheme using electro-hydraulic servo valves offers high control precision but is expensive and susceptible to oil contamination; while mechanical damping schemes, although lower in cost, struggle to achieve precise control and rapid response.

[0004] Furthermore, most existing hydraulic pulsation suppression devices can only suppress pulsations within a specific frequency band, making it difficult to achieve effective control across the entire frequency range. With the increasing demands on hydraulic system performance in industrial applications, there is an urgent need to develop a hydraulic pulsation suppression device that can achieve high-frequency dynamic adaptive adjustment, has a simple and reliable structure, fast response speed, and reasonable cost. Summary of the Invention

[0005] The main technical problem to be solved by the present invention is to provide a plunger pump oil pulsation suppression device that can respond quickly and dynamically and adaptively adjust at high frequency.

[0006] To solve the above-mentioned technical problems, the present invention provides a piezoelectric adjustable cavity plunger pump outlet pulsation suppression device, including an oil outlet pipe and several resonance absorbers.

[0007] One end of the oil outlet pipe is fixed to the oil outlet of the plunger pump and is connected to the oil outlet channel of the plunger pump; the plurality of resonance absorbers are spaced apart along the axial direction of the oil outlet pipe.

[0008] The resonant absorber includes a housing and a piezoelectric diaphragm; one end of the housing is hermetically connected to the oil outlet pipe; the piezoelectric diaphragm is hermetically connected to the inner wall of the housing, dividing the housing axially into an independent oil chamber and a resonant chamber; the oil chamber is located on the side of the piezoelectric diaphragm facing the oil outlet pipe and is connected to the oil outlet pipe; the piezoelectric diaphragm outputs a voltage signal in real time after sensing the oil pulsation in the oil outlet pipe;

[0009] The resonant absorber further includes a piston mechanism; the piston mechanism is disposed on the side of the resonant cavity away from the piezoelectric film, and a sealed air region is constructed between the piston mechanism and the piezoelectric film; the piston mechanism adjusts the volume of the air region by moving along the axial direction of the resonant cavity, so that the air region generates vibration with the same frequency as the oil pulsation.

[0010] The resonant absorber also includes a controller; the controller is connected to the piezoelectric diaphragm and the piston mechanism; the controller functions to: process the voltage signal from the piezoelectric diaphragm; calculate at least the pulsation frequency in the oil chamber based on the processed voltage signal; and output a control signal to the piston mechanism based on the pulsation frequency to control the piston mechanism to adjust the volume of the air zone.

[0011] In a preferred embodiment, the resonance absorber is disposed vertically at the bottom of the oil outlet pipe.

[0012] In a preferred embodiment, the piston mechanism is hydraulically operated and includes a secondary oil passage, an inlet switch valve, and an outlet switch valve.

[0013] The auxiliary oil path is led out from the outlet of the plunger pump, flows through the resonant cavity, and enters the oil tank; the auxiliary oil path forms an oil zone at the bottom of the resonant cavity;

[0014] The inlet switch valve is connected in series between the plunger pump and the resonant cavity, and the outlet switch valve is connected in series between the resonant cavity and the oil tank; after receiving the control signal, the inlet switch valve and the outlet switch valve quickly perform opening and closing operations to adjust the height of the oil zone.

[0015] In a preferred embodiment, the bottom of the resonant cavity is provided with an oil inlet and an oil outlet; the top of the oil inlet switch valve is sealed to the oil inlet, and the bottom is connected to the oil outlet of the plunger pump; the top of the oil outlet switch valve is sealed to the oil outlet, and the bottom is connected to the oil tank.

[0016] In a preferred embodiment, the housing is a cylindrical structure.

[0017] In a preferred embodiment, a flange is also included: the oil outlet pipe is horizontally fixed to the oil outlet of the plunger pump through the flange;

[0018] The flange is fixed to the outer periphery of the plunger pump outlet by a number of bolts; a sealing ring is provided between the flange and the plunger pump.

[0019] In a preferred embodiment, a clearance through hole is provided on the wall of the oil outlet pipe; the oil chamber is connected to the oil outlet pipe through the clearance through hole.

[0020] In a preferred embodiment, the piezoelectric film is made of a flexible material; when the piezoelectric film is in its natural state, it protrudes toward one side of the oil cavity.

[0021] In a preferred embodiment, the controller includes a signal processing module and a computing module;

[0022] The signal processing module performs functions such as signal filtering, signal amplification, and signal denoising on the voltage signal transmitted from the piezoelectric film.

[0023] The calculation module's functions include: calculating the pulsation frequency and amplitude of the oil in the outlet pipe based on the processed voltage signal.

[0024] In a preferred embodiment, the control signal is a pulse width modulation signal.

[0025] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0026] The device provided by this invention ingeniously combines piezoelectric film detection technology with high-speed switching valve control technology, achieving millisecond-level dynamic response capability. The device can adaptively adjust the resonant cavity parameters based on real-time detected pulsation signals, effectively suppressing oil pulsation across the entire frequency band.

[0027] The device employs a simple and reliable mechanical structure, reducing the use of complex components and lowering manufacturing and maintenance costs. Inside the resonant absorber, the high-speed switching valve has only inlet and outlet ports, greatly reducing oil contamination, while the excellent sealing properties of the piezoelectric diaphragm ensure reliable system operation.

[0028] In addition, the device is equipped with several resonance absorption devices in parallel. This modular design facilitates installation, maintenance and replacement, and provides a new technical solution with important engineering application value for suppressing hydraulic system oil pulsation. Attached Figure Description

[0029] Figure 1 This is a three-dimensional schematic diagram (partial cross-section) of the device described in an embodiment of the present invention;

[0030] Figure 2 This is a cross-sectional schematic diagram of the oil outlet pipe and the resonance absorber in an embodiment of the present invention (the oil inlet switch valve and the oil outlet switch valve are simplified representations);

[0031] Figure 3 This is a schematic diagram illustrating the working principle of the device described in the embodiments of the present invention;

[0032] Figure 4 This is a comparison chart showing the pressure pulsation suppression effect of the device described in the embodiments of the present invention.

[0033] The diagram is labeled as follows: 1-Resonance absorber, 11-Housing, 111-Oil inlet, 112-Oil outlet, 12-Piezoelectric diaphragm, 13-Oil chamber, 14-Resonance chamber, 141-Air zone, 142-Oil zone, 15-High-speed switching valve, 151-Oil inlet switching valve, 152-Oil outlet switching valve, 16-Controller, 2-Oil outlet pipe, 3-Flange, 4-Plunger pump outlet, 5-Oil tank. Detailed Implementation

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0035] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "top / bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0036] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed", "equipped", "sleeved / connected", "connected", etc., should be interpreted broadly. For example, "connection" can be a wall-mounted connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0037] like Figures 1-4As shown in the figure, this embodiment of the invention provides a piezoelectric adjustable cavity plunger pump outlet pulsation suppression device, including an oil outlet pipe 2 and a plurality of resonance absorbers 1. In terms of overall structure, one end of the oil outlet pipe 2 is fixed to the oil outlet 4 of the plunger pump and communicates with the oil outlet channel of the plunger pump. The plurality of resonance absorbers 1 are spaced apart at the bottom of the oil outlet pipe 2 along the axial direction of the oil outlet pipe 2. The resonance absorbers 1 are arranged vertically, with their tops communicating with the oil outlet pipe 2. The specific structure and connection relationships of each part of the device will now be described in detail with reference to the accompanying drawings.

[0038] The resonant absorber 1 includes a housing 11, a piezoelectric diaphragm 12, a piston mechanism, and a controller 16. The top of the housing 11 is hermetically connected to the oil outlet pipe 2. The piezoelectric diaphragm 12 is hermetically connected to the inner wall of the housing 11, dividing the housing 11 axially into an independent oil chamber 13 and a resonant chamber 14. The oil chamber 13 is connected to the oil outlet pipe 2 through a clearance through-hole provided on the pipe wall of the oil outlet pipe 2. In this way, when the oil chamber 13 is filled with oil, as long as there is pulsation in the oil in the oil outlet pipe 2, a high-frequency time-varying pressure will be generated on the surface of the piezoelectric diaphragm 12, causing the piezoelectric diaphragm 12 to generate a voltage signal due to the piezoelectric effect. In this embodiment, the housing 11 adopts a cylindrical structure. The inner diameter of the oil chamber 13 is 50-80 mm, and the height is 30-50 mm. The inner wall of the oil chamber 13 is precision machined to achieve a surface roughness Ra≤0.8 μm to reduce oil flow resistance. The resonant cavity 14 has an inner diameter of 60-100 mm and a height of 80-120 mm, and its inner wall is also precision machined. The clearance through-hole on the wall of the oil outlet pipe 2 has a diameter of 15-25 mm, providing sufficient flow area to allow the piezoelectric diaphragm 12 to promptly and fully sense pulsating oil pressure. In this embodiment, the piezoelectric diaphragm 12 is made of flexible zirconium titanate (PZT) piezoelectric ceramic material with a thickness of 0.2-0.5 mm and an effective working area of ​​2000-3000 mm². 2 The piezoelectric diaphragm 12 has a natural frequency above 1000Hz, which can fully respond to high-frequency pulsations in the oil pipeline. The piezoelectric diaphragm 12 is installed using a special sealing structure to ensure good sealing between it and the housing 11 even when the working pressure reaches 20MPa. Furthermore, to improve the sensing sensitivity, the piezoelectric diaphragm 12 protrudes towards the side of the oil cavity 13 in its natural state.

[0039] In general, when the piezoelectric diaphragm 12 senses oil pulsations in the oil outlet pipe, it feeds back a corresponding voltage signal, causing the resonant absorber 1 to change the volume of air in the resonant cavity 14, forming a Helmholtz resonant cavity 14. The Helmholtz resonant cavity 14 generates vibrations at the same frequency as the oil pulsations to dissipate their energy, thereby effectively suppressing the oil pulsations. How to adaptively adjust the volume of air in the resonant cavity 14 in a timely manner according to the voltage signal fed back by the piezoelectric diaphragm 12 is achieved through the piston mechanism and the controller 16.

[0040] like Figures 1-2 As shown, the piston mechanism in this embodiment employs a hydraulic piston. To make the device structure more compact, the liquid used is oil drawn from the plunger pump. Specifically, the piston mechanism includes a secondary oil passage and a set of high-speed switching valves 15. The secondary oil passage is led out from the oil outlet 4 of the plunger pump, flows through the resonant cavity 14, and enters the oil tank 5. The secondary oil passage accumulates a certain height of oil at the bottom of the resonant cavity 14. Correspondingly, to improve durability, the inner wall and bottom of the resonant cavity 14 are covered with a special anti-corrosion coating. For ease of description, the section of the resonant cavity 14 filled with oil is defined as the oil zone 142. Air is filled between the oil zone 142 and the piezoelectric membrane 12 to form a sealed air zone 141. It is easy to understand that a sealed medium interface exists between the air zone 141 and the oil zone 142. This embodiment involves frequently adjusting the height of the oil zone 142, causing the medium interface to continuously move up and down along the axis of the resonant cavity 14, thereby promptly changing the volume of the air zone 141. In this embodiment, the height of the oil zone 142 is dynamically adjusted within the range of 0-80mm.

[0041] Relative to the oil zone 142, the high-speed switching valve 15 is divided into an inlet switching valve 151 and an outlet switching valve 152. The inlet switching valve 151 is connected in series between the plunger pump and the resonant cavity 14, and the outlet switching valve 152 is connected in series between the resonant cavity 14 and the oil tank 5. Specifically, the bottom of the resonant cavity 14 is provided with an inlet hole 111 and an outlet hole 112. The inlet switching valve 151 is vertically arranged, with its top sealed to the inlet hole 111 and its bottom connected to the outlet port 4 of the plunger pump; the outlet switching valve 152 is also vertically arranged, with its top sealed to the outlet hole 112 and its bottom connected to the oil tank 5. When both the inlet valve 151 and the outlet valve 152 are open, the oil exits from the plunger pump outlet 4, passes through the inlet valve 151 and the inlet hole 111, enters the resonant cavity 14, and then passes through the outlet hole 112 and the outlet valve 152 into the oil tank 5. Therefore, when the outlet valve 152 is closed and the inlet valve 151 is open, the oil enters the resonant cavity 14, the height of the oil zone 142 rises, and the volume of the air zone 141 is compressed; when the inlet valve 151 is closed and the outlet valve 152 is open, the height of the oil zone 142 decreases, and the volume of the air zone 141 increases. In this embodiment, the inlet switch valve 151 and the outlet switch valve 152 adopt an electromagnetic direct-acting structure with a maximum operating frequency of 200Hz, i.e., a response time of less than 5ms. The valve orifice diameter is 2-4mm, and the rated flow rate is 5-10 liters / minute. They possess high-frequency dynamic response and precise flow control characteristics, enabling rapid adjustment of the height of the oil zone 142 within the resonant cavity 14. The inlet switch valve 151 and the outlet switch valve 152 are made of high-strength stainless steel, exhibiting excellent wear resistance and fatigue resistance. Furthermore, the bottom of the resonant cavity 14 is only provided with the inlet hole 111 and the outlet hole 112, effectively reducing oil contamination.

[0042] As an equivalent alternative to this embodiment, in other embodiments, the high-speed switching valve 15 can also be a fast-response oil pump, which can change the volume of the air zone 141 by independently pumping or extracting liquid into the resonant cavity 14. In another embodiment, the piston mechanism can also be pneumatic. Specifically, the resonant cavity 14 is divided into a first air chamber and a second air chamber along the axial direction by a baffle, which is slidably connected to the inner wall of the resonant cavity 14. The air chamber closest to the piezoelectric membrane 12 is now designated as the first air chamber. It is easy to understand that the baffle is the medium interface mentioned above, and the first air chamber is the air zone 141 mentioned above. The high-speed switching valve 15 is replaced by a fast-response air pump, which drives the baffle to slide towards or away from the piezoelectric membrane 12 by supplying or extracting air to the second air chamber, thereby changing the volume of the first air chamber.

[0043] The piston structure is the execution module of the device and does not have decision-making function itself. Therefore, the controller 16 is the core component in order for the resonant absorber 1 to adaptively adjust the air volume in the resonant cavity 14 according to the frequency and amplitude of the oil pulsation.

[0044] like Figures 1-2As shown, the controller 16 is located outside the resonant absorber 1 and is connected to the piezoelectric diaphragm 12, the inlet switch valve 151, and the outlet switch valve 152. The controller 16 includes a signal processing module and a calculation module. When the piezoelectric diaphragm 12 senses pulsating oil pressure, it deforms and generates a voltage signal. The voltage signal enters the controller 16, where the signal processing module performs signal filtering, signal amplification, and signal denoising. Based on the processed voltage signal, the calculation module calculates the pulsation frequency and amplitude of the oil in the outlet pipe 2, and uses this to estimate the target volume of the air region 141 in the resonant cavity 14 (see the calculation and deduction process described below). Then, the controller 16 outputs a control signal to the inlet switch valve 151 or the outlet switch valve 152 according to the calculation result, instructing the latter two to open or close. In this embodiment, the control signal is a pulse width modulation (PWM) signal, hereinafter referred to as the PWM signal. As mentioned above, by adjusting the opening and closing states of the oil inlet switch valve 151 and the oil outlet switch valve 152, the height of the oil zone 142 and the volume of the air zone 141 within the resonant cavity 14 can be adjusted, thereby generating vibrations at the same frequency as the oil pulsation to suppress it. It should be further noted that, as shown in the following deductions, although the real-time sensed oil pulsation frequency has a more decisive indicative significance for adjusting the volume of the air zone 141, the oil pulsation amplitude also plays an important role in the stable operation of the device. It characterizes the vibration intensity and noise level of the oil pulsation, reflects the urgency and response level of pulsation suppression, and helps the controller 16 output more timely and accurate PWM signals. From another perspective, recording the real-time pulsation amplitude helps in subsequent analysis of the device's vibration reduction and noise reduction effects, and has important guiding significance for product fault diagnosis, regular maintenance, and technical improvement.

[0045] In this embodiment, the controller 16 employs a 32-bit high-performance microprocessor with a sampling frequency of no less than 10kHz and 16-bit AD conversion accuracy. The signal processing module uses a digital filtering algorithm, including a low-pass filter (cutoff frequency 500Hz) and a band-pass filter (bandwidth 50-450Hz). The calculation module uses a Fast Fourier Transform (FFT) algorithm to analyze the pulsation spectrum characteristics in real time, with a control period of less than 1 millisecond. The PWM signal emitted by the controller 16 has a frequency of 1kHz, and its duty cycle can be continuously adjusted within the range of 0-100%, with a resolution of 0.1%. The controller 16 also has a CAN communication interface, enabling data interaction with a host computer to achieve real-time monitoring and adjustment of system parameters.

[0046] In terms of installation, the device has a flange 3 at one end of the oil outlet pipe 2, and is horizontally fixed to the oil outlet 4 of the plunger pump via the flange 3. The flange 3 is equipped with several M10 high-strength bolts for detachable connection to the outer periphery of the oil outlet 4 of the plunger pump. An O-ring is also provided between the flange 3 and the plunger pump to ensure a tight seal. When fixing the resonance absorber 1 to the bottom of the oil outlet pipe 2, preferably, the distance between two adjacent resonance absorbers 1 is not less than 100mm to ensure ease of installation and maintenance. In terms of wiring, the upstream oil pipes connected to the several inlet switch valves 151 converge and connect to the plunger pump; the downstream oil pipes connected to the several drain switch valves 152 converge and are placed in the oil tank 5. The control circuits of the several resonance absorbers 1 are converged into a controller 16, but each resonance absorber 1 can be controlled independently. In this embodiment, the operating temperature range of the device is -20℃ to +80℃, and the ambient humidity requirement is not greater than 85%RH. The device has a maximum system operating pressure of 21 MPa and a rated flow rate range of 20-200 liters / minute. Under nominal operating conditions, the device has a noise reduction effect of more than 4 dB for oil pulsation in the 50-400 Hz frequency band.

[0047] Now combined Figure 3 The vibration reduction and noise reduction principle of the device is summarized as follows: When the oil in the oil outlet pipe 2 flows through the oil chamber 13, the oil pulsation changes apply a high-frequency time-varying pressure to the piezoelectric diaphragm 12 at the bottom of the oil chamber 13. The piezoelectric diaphragm 12 generates a changing voltage signal due to the piezoelectric effect and transmits this voltage signal to the controller 16. The controller 16 amplifies and filters the voltage signal and calculates the oil pulsation frequency and amplitude. Based on the calculation result, it outputs a PWM signal to adjust the opening and closing states of the oil inlet switch valve 151 and the oil outlet switch valve 152. The opening and closing states of the oil inlet switch valve 151 and the oil outlet switch valve 152 cause a change in the height of the oil zone 142 in the resonant cavity 14, thereby changing the volume of the air zone 141. This causes the air in the cavity to form a Helmholtz resonant cavity 14, generating vibrations at the same frequency as the oil pulsation to dissipate its energy, thus effectively suppressing the oil pulsation. The device monitors the pulsating oil pressure in the oil chamber 13 in real time and continuously adjusts the volume of the air zone 141 in the resonant chamber 14 to achieve adaptive suppression of oil pulsation. Simultaneously, multiple resonant absorbers 1 are connected in parallel at the bottom of the oil outlet pipe 2, sequentially absorbing oil pulsations at different frequency ranges.

[0048] The method for calculating the volume of the air region 141 within the resonant cavity 14 is described below. For a cylindrical container, the resonant frequency of the sound wave depends on its radial and axial vibration modes, each with its specific resonant frequency, determined by the size and shape of the container and the speed of sound. Since the device provided in this embodiment primarily reduces noise through axial friction between air and the inner wall of the resonant cavity 14, the controller 16 only needs to calculate the resonant frequency in the axial mode.

[0049] For the axial mode in a cylindrical container, the Helmtz equation can be simplified to the following form:

[0050]

[0051] Where P is the sound pressure as a function of the height z of the sound wave propagation in the container, and k is the wave number.

[0052] Solving equation ①, we get

[0053] P(z)=Asin(kz)+Bcos(kz) ②

[0054] A and B are undetermined coefficients.

[0055] Apply boundary conditions:

[0056]

[0057] Where L is the height of the cylindrical container.

[0058] Substituting equation ③ into equation ②, we get the solution.

[0059]

[0060] Where n is the mode number, i.e. the number of nodes in axial vibration.

[0061] Substituting equation ④ into the formula for calculating the wave number k:

[0062]

[0063] Where c is the speed of sound, f n The resonant frequency corresponding to the air region 141.

[0064] Solve equations ④ and ⑤ simultaneously to obtain the answer.

[0065]

[0066] Substituting the volume V = S·L of the air region 141 into equation ⑥, and letting f n =f, find

[0067]

[0068] Where f is the pulsation frequency of the oil in the current oil outlet pipe 2, and S is the horizontal cross-sectional area of ​​the resonant cavity 14.

[0069] As can be seen from equation ⑦, the target volume of the air region 141 in the resonant cavity can be calculated based on the oil pulsation frequency obtained from the voltage signal transmitted from the piezoelectric film 12.

[0070] The working principle of the device is not limited to a cylindrical resonant absorber. In other embodiments, the resonant cavity 14 can also be constructed in other shapes, including a square columnar structure. The difference lies in the fact that different shapes of the resonant cavity 14 will have different resonant frequencies and vibration modes, and the specific calculation formula needs to be derived according to the specific situation. For example, for a square columnar resonant cavity 14, it is first necessary to consider the vibration modes in each direction, including vibrations along the length, width, and height directions; and each vibration mode has its specific resonant frequency. The resonant frequency of the axial mode of the square columnar resonant cavity 14 is determined by the length of the container and the speed of sound in the air, while the resonant frequency of the lateral mode is determined by the width and height of the container and the sound wave propagation characteristics in the corresponding direction. In particular, the vibration of the axial mode of the square columnar resonant cavity 14 is similar to that of the cylindrical resonant cavity. Therefore, based on the derivation results, the resonant frequency of its axial mode can usually be calculated with reference to formula ⑥. Correspondingly, L is changed to the length of the square container.

[0071] In the above deduction process, the number of modes n can be understood as the first few frequencies that need to be attenuated for oil pulsation. Users can select these according to their needs to control the controller 16 to output different PWM signals. Referring to the suppression effect comparison described below, in Figure 4 On the horizontal axis, we can see that starting from 0, there are a total of 10 peak frequencies. Therefore, in this embodiment, the number of modes n is 10.

[0072] like Figure 4As shown, this paper compares the pressure pulsation suppression effect of the provided device with that of a device without vibration damping and a traditional vibration damping device. It can be seen that the pipeline pressure fluctuation is greatest when the device without vibration damping is configured, while the pressure pulsation in the low-frequency region is significantly reduced after configuring the traditional vibration damping device and the device provided in this embodiment. Compared with the traditional vibration damping device, the device also achieves a reduction in pressure pulsation in the high-frequency region. This is because the device adopts a dynamic adaptive resonant cavity structure, which can automatically adjust the gas volume in the resonant cavity according to the pressure pulsation at different frequencies, forming cavities with multiple different channels. Combined with the optimized resonant cavity structure, it can generate fluctuations with the opposite phase to the pressure pulsation. The design of the device retains the advantage of traditional vibration damping devices in suppressing pulsation in the low-frequency region through impedance matching, and also achieves effective vibration damping in the high-frequency region through the synergistic effect of the dynamic response mechanism and the resonant cavity effect, thereby achieving a pressure pulsation suppression effect across the entire frequency band. In contrast, traditional vibration damping devices mainly rely on impedance matching with fixed parameters, and their suppression effect in the high-frequency region is relatively limited.

[0073] The above description is merely a preferred embodiment of the present invention and is not intended to limit the patent scope of the present invention. Any technically equivalent modifications made based on the content of this specification shall fall within the protection scope of the present invention.

Claims

1. A piezoelectric adjustable-cavity plunger pump outlet pulsation suppression device, characterized in that: Includes an oil outlet pipe and several resonance absorbers; One end of the oil outlet pipe is fixed to the oil outlet of the plunger pump and is connected to the oil outlet channel of the plunger pump; the plurality of resonance absorbers are spaced apart along the axial direction of the oil outlet pipe. The resonant absorber includes a housing and a piezoelectric diaphragm; one end of the housing is hermetically connected to the oil outlet pipe; the piezoelectric diaphragm is hermetically connected to the inner wall of the housing, dividing the housing axially into an independent oil chamber and a resonant chamber; the oil chamber is located on the side of the piezoelectric diaphragm facing the oil outlet pipe and is connected to the oil outlet pipe; the piezoelectric diaphragm outputs a voltage signal in real time after sensing the oil pulsation in the oil outlet pipe; The resonant absorber further includes a piston mechanism; the piston mechanism is disposed on the side of the resonant cavity away from the piezoelectric film, and a sealed air region is constructed between the piston mechanism and the piezoelectric film; the piston mechanism adjusts the volume of the air region by moving along the axial direction of the resonant cavity, so that the air region generates vibration with the same frequency as the oil pulsation. The resonant absorber also includes a controller; the controller is connected to the piezoelectric diaphragm and the piston mechanism; The controller functions to: process the voltage signal from the piezoelectric diaphragm; calculate at least the pulsation frequency in the oil chamber based on the processed voltage signal; and output a control signal to the piston mechanism based on the pulsation frequency to control the piston mechanism to adjust the volume of the air zone.

2. The piezoelectric adjustable-cavity plunger pump outlet pulsation suppression device according to claim 1, characterized in that: The resonance absorber is vertically positioned at the bottom of the oil outlet pipe.

3. The piezoelectric adjustable-cavity plunger pump outlet pulsation suppression device according to claim 2, characterized in that: The piston mechanism is hydraulically operated and includes a secondary oil passage, an inlet switch valve, and an outlet switch valve. The auxiliary oil path is led out from the outlet of the plunger pump, flows through the resonant cavity, and enters the oil tank; the auxiliary oil path forms an oil zone at the bottom of the resonant cavity; The inlet switch valve is connected in series between the plunger pump and the resonant cavity, and the outlet switch valve is connected in series between the resonant cavity and the oil tank; after receiving the control signal, the inlet switch valve and the outlet switch valve quickly perform opening and closing operations to adjust the height of the oil zone.

4. The piezoelectric adjustable-cavity plunger pump outlet pulsation suppression device according to claim 3, characterized in that: The bottom of the resonant cavity is provided with an oil inlet and an oil outlet; the top of the oil inlet switch valve is sealed to the oil inlet, and the bottom is connected to the oil outlet of the plunger pump; the top of the oil outlet switch valve is sealed to the oil outlet, and the bottom is connected to the oil tank.

5. The piezoelectric adjustable-cavity plunger pump outlet pulsation suppression device according to claim 1, characterized in that: The shell is a cylindrical structure.

6. The piezoelectric adjustable-cavity plunger pump outlet pulsation suppression device according to claim 1, characterized in that: It also includes a flange; the oil outlet pipe is horizontally fixed to the oil outlet of the plunger pump through the flange; The flange is fixed to the outer periphery of the plunger pump outlet by a number of bolts; a sealing ring is provided between the flange and the plunger pump.

7. The piezoelectric adjustable-cavity plunger pump outlet pulsation suppression device according to claim 1, characterized in that: The oil outlet pipe wall is provided with a clearance through hole; the oil chamber is connected to the oil outlet pipe through the clearance through hole.

8. The piezoelectric adjustable-cavity plunger pump outlet pulsation suppression device according to claim 1, characterized in that: The piezoelectric membrane is made of a flexible material; when the piezoelectric membrane is in its natural state, it protrudes towards one side of the oil cavity.

9. The piezoelectric adjustable-cavity plunger pump outlet pulsation suppression device according to claim 1, characterized in that: The controller includes a signal processing module and a computing module; The signal processing module performs signal filtering, signal amplification, and signal denoising on the voltage signal transmitted from the piezoelectric film. The calculation module's functions include: calculating the pulsation frequency and amplitude of the oil in the outlet pipe based on the processed voltage signal.

10. The piezoelectric adjustable-cavity plunger pump outlet pulsation suppression device according to claim 1, characterized in that: The control signal is a pulse width modulation signal.

Images