Vibration suppression and energy efficiency improvement method for marine propulsion system

Abstract

The invention discloses a vibration suppression and energy efficiency improvement method for a marine propulsion system, and belongs to the technical field of ship vibration control and energy efficiency optimizing.The method comprises the steps that vibration signals at a middle bearing, a propeller hub and a main engine base are collected, and three paths of filtering signals are obtained through band-pass filtering; front and rear flow velocity signals and main shaft rotating speed signals of a propeller are collected, and the ratio of the flow velocity difference to the rotating speed difference is calculated to obtain an energy efficiency coefficient; the three paths of filtering signals are multiplied by the energy efficiency coefficient to generate three paths of control signals, and the three paths of control signals are output to the three piezoelectric actuators to generate displacement amounts which act on a bearing shell, the inner wall of a propeller hub and a main engine base; when the propulsion shafting vibrates longitudinally, the metal push rod drives the coil to reciprocate between the permanent magnets to generate induced current, the induced current is stored in the storage battery after being rectified and supplied to the hydraulic controller to adjust the oil flow of the hydraulic cylinder according to a control signal, and graded suppression of multi-source vibration and recycling of vibration energy are achieved. And the vibration suppression effect and the energy efficiency level of the system are obviously improved.

Description

Technical Field

[0001] This invention relates to the field of ship vibration control and energy efficiency optimization technology, and more specifically, to a method for vibration suppression and energy efficiency improvement of a marine propulsion system. Background Technology

[0002] The ship's propulsion system is a core component of its power plant, primarily comprising the main engine, propulsion shaft system, and propeller. The power output from the main engine is transmitted to the propeller via the propulsion shaft system, and the propeller's rotation generates thrust, propelling the ship forward. During navigation, the propulsion system is subjected to various excitation sources, including periodic excitation from the main engine's operation, blade frequency excitation from the propeller's rotation in a non-uniform wake field, mechanical excitation caused by shaft misalignment, and hydrodynamic excitation caused by changes in sea state. These excitation sources work together to produce a complex vibration response in the propulsion system, mainly including longitudinal, torsional, and lateral vibrations of the shaft system, as well as blade frequency vibrations at the propeller and vibrations at the main engine base. Excessive vibration not only affects the ship's comfort and safety but also accelerates fatigue damage to various components of the propulsion system, reducing its service life and reliability.

[0003] To address the vibration problem in ship propulsion systems, some suppression methods and devices exist in the prior art. For example, patent CN114148501B discloses a longitudinal vibration suppression device for ship shafting, which uses a hydraulic actuator at the thrust bearing to generate a counterforce based on the longitudinal vibration signal of the shafting to suppress longitudinal vibration. However, this device only suppresses longitudinal vibration and fails to consider hydrodynamic vibration at the propeller and structural vibration at the main engine base, and it does not optimize energy efficiency during ship navigation. Another example is patent application CN115432150A, which proposes a vibration control method for ship propulsion systems. This method collects shafting vibration signals and main engine speed signals, and uses an adaptive control algorithm to control a magnetorheological elastomer actuator to generate damping force. While this method achieves comprehensive control of multi-source vibration, it consumes a large amount of electrical energy during the control process, fails to utilize vibration energy for recovery and reuse, and does not incorporate hydrodynamic parameters into the control strategy, resulting in limited energy efficiency improvement. In addition, commonly used vibration suppression methods in existing technologies, such as passive vibration isolation and dynamic vibration absorbers, are difficult to adapt to the complex conditions of changes in operating conditions and sea conditions during ship navigation, and the vibration suppression effect is unstable. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides a method for vibration suppression and energy efficiency improvement in marine propulsion systems, thus solving the aforementioned problems.

[0006] (II) Technical Solution

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: a method for vibration suppression and energy efficiency improvement of a marine propulsion system, wherein the marine propulsion system includes a propulsion shaft system, a marine main engine, and a propeller; the propulsion shaft system includes a main shaft, a coupling, and an intermediate bearing; one end of the main shaft is connected to the output end of the marine main engine via the coupling; the middle part of the main shaft is rotatably connected to the intermediate bearing; and the other end of the main shaft is connected to the propeller; the method includes the following steps:

[0008] Step a: Collect the first vibration signal at the intermediate bearing of the propulsion shaft system, collect the second vibration signal inside the propeller hub, and collect the third vibration signal at the base of the ship's main engine.

[0009] Step b: Collect the first flow velocity signal in front of the propeller, collect the second flow velocity signal behind the propeller, and collect the rotational speed signal of the main shaft of the propulsion shaft system;

[0010] Step c: Perform bandpass filtering on the first vibration signal to obtain a first filtered signal, perform bandpass filtering on the second vibration signal to obtain a second filtered signal, and perform bandpass filtering on the third vibration signal to obtain a third filtered signal;

[0011] Step d: Calculate the difference between the first flow velocity signal and the second flow velocity signal to obtain the flow velocity difference signal; calculate the difference between the rotational speed signal and the preset rotational speed setting value to obtain the rotational speed difference signal; calculate the ratio of the flow velocity difference signal to the rotational speed difference signal to obtain the energy efficiency coefficient.

[0012] Step e: Multiply the first filtered signal by the energy efficiency coefficient to obtain a first control signal, multiply the second filtered signal by the energy efficiency coefficient to obtain a second control signal, and multiply the third filtered signal by the energy efficiency coefficient to obtain a third control signal;

[0013] Step f: Output the first control signal to the first piezoelectric actuator, output the second control signal to the second piezoelectric actuator, and output the third control signal to the third piezoelectric actuator;

[0014] Step g: When the propulsion shaft system vibrates longitudinally, the induced current generated by the reciprocating motion of the coil driven by the metal push rod between the first permanent magnet and the second permanent magnet is rectified and stored in the battery.

[0015] Step h: Output the electrical energy stored in the battery to the hydraulic controller, and control the hydraulic oil flow of the hydraulic cylinder according to the first control signal, the second control signal and the third control signal.

[0016] Step i: Output the energy efficiency coefficient, the first filter signal, the second filter signal, and the third filter signal to the display unit.

[0017] Preferably, step c, bandpass filtering of the first vibration signal, includes: transmitting the first vibration signal to the input of a first charge amplifier via a first shielded cable, amplifying the first vibration signal via the first charge amplifier, transmitting the amplified first vibration signal to the input of a first bandpass filter via a first signal line, and performing bandpass filtering on the amplified first vibration signal via the first bandpass filter to filter out signal components with frequencies lower than a first lower limit frequency and higher than a first upper limit frequency, thereby obtaining the first filtered signal;

[0018] Bandpass filtering of the second vibration signal includes: transmitting the second vibration signal to the input of a second charge amplifier via a second shielded cable; amplifying the second vibration signal via the second charge amplifier; transmitting the amplified second vibration signal to the input of a second bandpass filter via a second signal line; and performing bandpass filtering on the amplified second vibration signal via the second bandpass filter to filter out signal components with frequencies lower than a second lower limit frequency and higher than a second upper limit frequency, thereby obtaining the second filtered signal. Bandpass filtering of the third vibration signal includes: transmitting the third vibration signal to the input of a third charge amplifier via a third shielded cable; amplifying the third vibration signal via the third charge amplifier; transmitting the amplified third vibration signal to the input of a third bandpass filter via a third signal line; and performing bandpass filtering on the amplified third vibration signal via the third bandpass filter to filter out signal components with frequencies lower than a third lower limit frequency and higher than a third upper limit frequency, thereby obtaining the third filtered signal.

[0019] Preferably, step d, calculating the difference between the first flow velocity signal and the second flow velocity signal, includes: transmitting the first flow velocity signal to the input terminal of the first analog-to-digital converter (ADC) via a fourth shielded cable; performing analog-to-digital conversion on the first flow velocity signal using the first ADC; transmitting the converted first flow velocity signal to the first input terminal of the first subtractor via a fourth signal line; transmitting the second flow velocity signal to the input terminal of the second ADC via a fifth shielded cable; performing analog-to-digital conversion on the second flow velocity signal using the second ADC; transmitting the converted second flow velocity signal to the second input terminal of the first subtractor via a fifth signal line; performing a subtraction operation on the converted first flow velocity signal and the converted second flow velocity signal using the first subtractor; and subtracting the converted second flow velocity signal from the converted first flow velocity signal to obtain the flow velocity difference signal.

[0020] Calculating the difference between the speed signal and the preset speed setting value includes: transmitting the speed signal to the input terminal of the third analog-to-digital converter through the sixth shielded cable; performing analog-to-digital conversion on the speed signal through the third analog-to-digital converter; transmitting the converted speed signal to the first input terminal of the second subtractor through the sixth signal line; transmitting the preset speed setting value to the second input terminal of the second subtractor through the seventh signal line; performing a subtraction operation between the converted speed signal and the preset speed setting value through the second subtractor; and subtracting the preset speed setting value from the converted speed signal to obtain the speed difference signal.

[0021] Calculating the ratio of the flow velocity difference signal to the rotational speed difference signal includes: transmitting the flow velocity difference signal to the first input terminal of the divider through the eighth signal line, transmitting the rotational speed difference signal to the second input terminal of the divider through the ninth signal line, performing a division operation on the flow velocity difference signal and the rotational speed difference signal through the divider, and dividing the flow velocity difference signal by the rotational speed difference signal to obtain the energy efficiency coefficient.

[0022] Preferably, step e, multiplying the first filtered signal with the energy efficiency coefficient, includes: transmitting the first filtered signal to the first input terminal of the first multiplier through the tenth signal line, transmitting the energy efficiency coefficient to the second input terminal of the first multiplier through the eleventh signal line, performing a multiplication operation on the first filtered signal and the energy efficiency coefficient through the first multiplier, and multiplying the first filtered signal by the energy efficiency coefficient to obtain the first control signal;

[0023] Multiplying the second filtered signal with the energy efficiency coefficient includes: transmitting the second filtered signal to the first input terminal of the second multiplier through the twelfth signal line, transmitting the energy efficiency coefficient to the second input terminal of the second multiplier through the thirteenth signal line, performing a multiplication operation on the second filtered signal and the energy efficiency coefficient through the second multiplier, and multiplying the second filtered signal by the energy efficiency coefficient to obtain the second control signal;

[0024] Multiplying the third filtered signal with the energy efficiency coefficient includes: transmitting the third filtered signal to the first input terminal of the third multiplier through the fourteenth signal line, transmitting the energy efficiency coefficient to the second input terminal of the third multiplier through the fifteenth signal line, performing a multiplication operation on the third filtered signal and the energy efficiency coefficient through the third multiplier, and multiplying the third filtered signal by the energy efficiency coefficient to obtain the third control signal.

[0025] Preferably, step f, in which the first control signal is output to the first piezoelectric actuator, includes: transmitting the first control signal to the input terminal of the first power amplifier through the sixteenth signal line; amplifying the first control signal through the first power amplifier; transmitting the amplified first control signal to the input terminal of the first piezoelectric actuator through the seventeenth signal line; and generating a first displacement amount according to the amplified first control signal, wherein the direction of the first displacement amount is perpendicular to the axis of the main shaft.

[0026] Outputting the second control signal to the second piezoelectric actuator includes: transmitting the second control signal to the input terminal of the second power amplifier through the eighteenth signal line; amplifying the second control signal through the second power amplifier; transmitting the amplified second control signal to the input terminal of the second piezoelectric actuator through the nineteenth signal line; and generating a second displacement amount according to the amplified second control signal, wherein the direction of the second displacement amount is parallel to the axis of the propeller.

[0027] Outputting the third control signal to the third piezoelectric actuator includes: transmitting the third control signal to the input terminal of the third power amplifier through the twentieth signal line; amplifying the third control signal through the third power amplifier; transmitting the amplified third control signal to the input terminal of the third piezoelectric actuator through the twentieth signal line; and generating a third displacement based on the amplified third control signal, wherein the direction of the third displacement is perpendicular to the base plane of the ship's main engine.

[0028] Preferably, the first piezoelectric actuator includes a first piezoelectric stack, a first flexible hinge, and a first output push rod. One end of the first piezoelectric stack is fixedly connected to the first end of the first flexible hinge, the second end of the first flexible hinge is fixedly connected to one end of the first output push rod, and the other end of the first output push rod abuts against the housing of the intermediate bearing.

[0029] The second piezoelectric actuator includes a second piezoelectric stack, a second flexible hinge, and a second output push rod. One end of the second piezoelectric stack is fixedly connected to the first end of the second flexible hinge, the second end of the second flexible hinge is fixedly connected to one end of the second output push rod, and the other end of the second output push rod abuts against the inner wall of the propeller hub.

[0030] The third piezoelectric actuator includes a third piezoelectric stack, a third flexible hinge, and a third output push rod. One end of the third piezoelectric stack is fixedly connected to the first end of the third flexible hinge, the second end of the third flexible hinge is fixedly connected to one end of the third output push rod, and the other end of the third output push rod abuts against the base of the ship's main engine.

[0031] Preferably, there are four hydraulic cylinders, namely a first hydraulic cylinder, a second hydraulic cylinder, a third hydraulic cylinder, and a fourth hydraulic cylinder. The four hydraulic cylinders are evenly distributed along the circumference of the main shaft. The four hydraulic cylinders are respectively fixed to the middle of the four support columns of the cross-shaped support plate. The cross-shaped support plate is located between the inner ring of the first permanent magnet and the outer ring of the second permanent magnet. The first permanent magnet is installed on the outside of the thrust bearing seat ring, and the second permanent magnet is installed on the outside of the main shaft. The front end of the metal push rod is fixedly connected to the coil, and the rear end of the metal push rod is fixedly connected to the piston rod of the hydraulic cylinder.

[0032] Preferably, the passband frequency range of the first bandpass filter is set to 5Hz to 50Hz. The first bandpass filter attenuates signal components with frequencies below 5Hz and above 50Hz, and retains signal components with frequencies in the range of 5Hz to 50Hz.

[0033] The passband frequency range of the second bandpass filter is set to 50Hz to 200Hz. The second bandpass filter attenuates signal components with frequencies below 50Hz and above 200Hz, and retains signal components with frequencies in the range of 50Hz to 200Hz.

[0034] The passband frequency range of the third bandpass filter is set to 200Hz to 500Hz. The third bandpass filter attenuates signal components with frequencies below 200Hz and above 500Hz, and retains signal components with frequencies in the range of 200Hz to 500Hz.

[0035] Preferably, in step g, the induced current generated by the reciprocating motion of the coil driven by the metal push rod between the first and second permanent magnets is rectified and stored in the battery, which includes: connecting the two ends of the coil to the AC input terminal of the rectifier circuit through the twenty-second and twenty-third signal lines; performing full-wave rectification on the induced current generated by the coil through the rectifier circuit; outputting the rectified DC power to the positive terminal of the battery through the twenty-fourth signal line; grounding the negative terminal of the battery through the twenty-fifth signal line; and connecting a filter capacitor in parallel between the positive and negative terminals of the battery, with one end of the filter capacitor connected to the positive terminal of the battery and the other end of the filter capacitor connected to the negative terminal of the battery.

[0036] Preferably, step h, which involves outputting the electrical energy stored in the battery to the hydraulic controller, includes: connecting the positive terminal of the battery to the positive power input terminal of the hydraulic controller via a 26th signal line, and connecting the negative terminal of the battery to the negative power input terminal of the hydraulic controller via a 27th signal line; controlling the opening of the first solenoid valve according to the first control signal, the opening of the second solenoid valve according to the second control signal, and the opening of the third solenoid valve according to the third control signal, wherein the first solenoid valve is installed on the oil inlet pipe of the first hydraulic cylinder, the second solenoid valve is installed on the oil inlet pipe of the second hydraulic cylinder, and the third solenoid valve is installed on the oil inlet pipe of the third hydraulic cylinder;

[0037] Step i, which involves outputting the energy efficiency coefficient, the first filtered signal, the second filtered signal, and the third filtered signal to the display unit, includes: outputting the energy efficiency coefficient to the first display input terminal of the display unit via the twenty-eighth signal line; outputting the first filtered signal to the second display input terminal of the display unit via the twenty-ninth signal line; outputting the second filtered signal to the third display input terminal of the display unit via the thirtieth signal line; and outputting the third filtered signal to the fourth display input terminal of the display unit via the thirty-first signal line. The display unit displays the current energy efficiency value based on the energy efficiency coefficient, displays a first vibration waveform based on the first filtered signal, displays a second vibration waveform based on the second filtered signal, and displays a third vibration waveform based on the third filtered signal.

[0038] (III) Beneficial Effects

[0039] Compared with the prior art, the present invention provides a method for vibration suppression and energy efficiency improvement of marine propulsion systems, which has the following beneficial effects:

[0040] 1. This method for vibration suppression and energy efficiency improvement in marine propulsion systems involves collecting vibration signals from three locations: the intermediate bearing of the propulsion shaft system, the propeller hub, and the main engine base. These signals are then amplified and bandpass filtered to obtain three filtered signals. Simultaneously, flow velocity signals in front of and behind the propeller and main shaft rotational speed signals are collected. The ratio of the flow velocity difference to the rotational speed difference is calculated to obtain the energy efficiency coefficient. The three filtered signals are multiplied by the energy efficiency coefficient to generate three control signals, which are output to three corresponding piezoelectric actuators to produce displacements acting on the intermediate bearing housing, the propeller hub inner wall, and the main engine base, respectively. This method achieves graded suppression and coordinated control of vibrations at different locations. Low-frequency, mid-frequency, and high-frequency vibration signals are extracted using bandpass filters of different frequency bands, effectively avoiding mutual interference between vibration signals and improving the targeting and accuracy of vibration suppression.

[0041] 2. This method for vibration suppression and energy efficiency improvement in a marine propulsion system involves generating an induced current by driving a coil to reciprocate between a first and second permanent magnet when longitudinal vibration occurs in the propulsion shaft. This current is rectified and stored in a battery, converting vibration energy into recoverable electrical energy. The stored electrical energy powers the hydraulic controller, which adjusts the hydraulic oil flow of each hydraulic cylinder based on three control signals, further actively suppressing longitudinal vibration. This method achieves vibration energy recovery and reuse, reducing system energy consumption. Furthermore, by combining active vibration suppression by the hydraulic cylinders with that by the piezoelectric actuator, a multi-stage vibration suppression mechanism is formed, significantly improving the vibration suppression effect and energy efficiency of the propulsion system. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the structure of the present invention;

[0043] Figure 2 This is a flowchart of the bandpass filtering process of the present invention;

[0044] Figure 3 This is a flowchart of the present invention;

[0045] Figure 4 This is a flowchart of the present invention;

[0046] Figure 5 This is a flowchart of the present invention;

[0047] Figure 6 This is a flowchart of the present invention. Detailed Implementation

[0048] 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, and 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.

[0049] Please see Figures 1-6 The present invention provides a technical solution:

[0050] Example 1:

[0051] A method for vibration suppression and energy efficiency improvement in a marine propulsion system, the specific implementation process of which is as follows:

[0052] First, sensors are installed at key components of the marine propulsion system. A first acceleration sensor is installed on the intermediate bearing housing of the propulsion shaft to collect vibration signals at the intermediate bearing. A second acceleration sensor is installed inside the propeller hub to collect vibration signals at the propeller. A third acceleration sensor is installed on the main engine mount to collect vibration signals at the main engine mount. A first flow sensor is installed at the stern of the hull in front of the propeller to collect water flow velocity signals in front of the propeller. A second flow sensor is installed at the stern of the hull behind the propeller to collect water flow velocity signals behind the propeller. A speed sensor is installed beside the main shaft of the propulsion shaft to collect the main shaft's rotational speed signals.

[0053] After sensor installation is complete, the signal acquisition and processing flow begins. Vibration, flow velocity, and rotational speed signals are acquired in real time by each sensor. The first vibration signal is transmitted via a first shielded cable to a first charge amplifier for amplification. The amplified first vibration signal is then input to a first bandpass filter for bandpass filtering, removing signal components with frequencies below 5Hz and above 50Hz, resulting in the first filtered signal. The second vibration signal is transmitted via a second shielded cable to a second charge amplifier for amplification. The amplified second vibration signal is then input to a second bandpass filter for bandpass filtering, removing signal components with frequencies below 50Hz and above 200Hz, resulting in the second filtered signal. The third vibration signal is transmitted via a third shielded cable to a third charge amplifier for amplification. The amplified third vibration signal is then input to a third bandpass filter for bandpass filtering, removing signal components with frequencies below 200Hz and above 500Hz, resulting in the third filtered signal.

[0054] The first flow velocity signal is transmitted to the first analog-to-digital converter (ADC) via the fourth shielded cable for analog-to-digital conversion. The converted first flow velocity signal is then input to the first input terminal of the first subtractor. The second flow velocity signal is transmitted to the second ADC via the fifth shielded cable for analog-to-digital conversion. The converted second flow velocity signal is then input to the second input terminal of the first subtractor. The first subtractor performs a subtraction operation on the converted first and second flow velocity signals, subtracting the second flow velocity signal from the first flow velocity signal to obtain the flow velocity difference signal. The rotational speed signal is transmitted to the third ADC via the sixth shielded cable for analog-to-digital conversion. The converted rotational speed signal is then input to the first input terminal of the second subtractor. The preset rotational speed setting value is transmitted to the second input terminal of the second subtractor via the seventh signal line. The second subtractor performs a subtraction operation on the converted rotational speed signal and the preset rotational speed setting value, subtracting the preset rotational speed setting value from the rotational speed signal to obtain the rotational speed difference signal. The flow velocity difference signal and the speed difference signal are input to the divider through the eighth signal line and the ninth signal line, respectively. The divider performs a division operation on the flow velocity difference signal and the speed difference signal, and the energy efficiency coefficient is obtained by dividing the flow velocity difference signal by the speed difference signal.

[0055] The first filtered signal is transmitted to the first input of the first multiplier via the tenth signal line, and the energy efficiency coefficient is transmitted to the second input of the first multiplier via the eleventh signal line. The first multiplier performs a multiplication operation on the first filtered signal and the energy efficiency coefficient, multiplying the first filtered signal by the energy efficiency coefficient to obtain the first control signal. The second filtered signal is transmitted to the first input of the second multiplier via the twelfth signal line, and the energy efficiency coefficient is transmitted to the second input of the second multiplier via the thirteenth signal line. The second multiplier performs a multiplication operation on the second filtered signal and the energy efficiency coefficient, multiplying the second filtered signal by the energy efficiency coefficient to obtain the second control signal. The third filtered signal is transmitted to the first input of the third multiplier via the fourteenth signal line, and the energy efficiency coefficient is transmitted to the second input of the third multiplier via the fifteenth signal line. The third multiplier performs a multiplication operation on the third filtered signal and the energy efficiency coefficient, multiplying the third filtered signal by the energy efficiency coefficient to obtain the third control signal.

[0056] The first control signal is transmitted to the input of the first power amplifier via the sixteenth signal line. The first power amplifier amplifies the first control signal, and the amplified first control signal is transmitted to the input of the first piezoelectric actuator via the seventeenth signal line. The first piezoelectric actuator generates a first displacement based on the amplified first control signal. The direction of this first displacement is perpendicular to the axis of the main shaft and acts on the intermediate bearing housing to suppress vibration at the intermediate bearing. The second control signal is transmitted to the input of the second power amplifier via the eighteenth signal line. The second power amplifier amplifies the second control signal, and the amplified second control signal is transmitted to the input of the second piezoelectric actuator via the nineteenth signal line. The second piezoelectric actuator generates a second displacement based on the amplified second control signal. The direction of this second displacement is parallel to the axis of the propeller and acts on the inner wall of the propeller hub to suppress vibration at the propeller. The third control signal is transmitted to the input of the third power amplifier via the twentieth signal line. The third power amplifier amplifies the third control signal, and the amplified third control signal is transmitted to the input of the third piezoelectric actuator via the twenty-first signal line. The third piezoelectric actuator generates a third displacement based on the amplified third control signal. The direction of this third displacement is perpendicular to the plane of the ship's main engine base and acts on the main engine base to suppress vibration at the main engine base.

[0057] When the propulsion shaft system experiences longitudinal vibration, a magnetic field is formed between the No. 1 permanent magnet mounted on the outside of the thrust bearing housing and the No. 2 permanent magnet mounted on the outside of the main shaft. Under the action of longitudinal vibration, the metal push rod drives the coil to reciprocate between the No. 1 and No. 2 permanent magnets, and the coil cuts the magnetic field lines to generate an induced current. The two ends of the coil are connected to the AC input terminal of the rectifier circuit through the 22nd and 23rd signal lines. The rectifier circuit performs full-wave rectification on the induced current generated by the coil, converting the AC power into DC power. The rectified DC power is output to the positive terminal of the battery through the 24th signal line, and the negative terminal of the battery is grounded through the 25th signal line. A filter capacitor is connected in parallel between the positive and negative terminals of the battery. One end of the filter capacitor is connected to the positive terminal of the battery, and the other end is connected to the negative terminal of the battery, used to filter the DC power.

[0058] The electrical energy stored in the battery is output to the power input terminal of the hydraulic controller via the 26th and 27th signal lines, providing operating power to the hydraulic controller. The first control input terminal of the hydraulic controller is connected to the output terminal of the first piezoelectric actuator to receive the first control signal; the second control input terminal is connected to the output terminal of the second piezoelectric actuator to receive the second control signal; and the third control input terminal is connected to the output terminal of the third piezoelectric actuator to receive the third control signal. The hydraulic controller controls the opening degree of the first solenoid valve according to the first control signal, the second solenoid valve according to the second control signal, and the third solenoid valve according to the third control signal. The first solenoid valve is installed on the oil inlet pipe of the first hydraulic cylinder, the second solenoid valve is installed on the oil inlet pipe of the second hydraulic cylinder, and the third solenoid valve is installed on the oil inlet pipe of the third hydraulic cylinder. By adjusting the opening degree of each solenoid valve, the hydraulic oil flow rate of each hydraulic cylinder is controlled, thereby further suppressing longitudinal vibration.

[0059] The energy efficiency coefficient calculated by the divider is output to the first display input terminal of the display unit via the twenty-eighth signal line. The first filtered signal output from the first bandpass filter is output to the second display input terminal of the display unit via the twenty-ninth signal line. The second filtered signal output from the second bandpass filter is output to the third display input terminal of the display unit via the thirtieth signal line. The third filtered signal output from the third bandpass filter is output to the fourth display input terminal of the display unit via the thirty-first signal line. The display unit displays the current energy efficiency value on the screen based on the received energy efficiency coefficient, displays the first vibration waveform based on the first filtered signal, the second vibration waveform based on the second filtered signal, and the third vibration waveform based on the third filtered signal, allowing operators to monitor the operating status of the propulsion system in real time.

[0060] Example 2:

[0061] Regarding sensor installation, the first accelerometer is installed on the upper surface of the intermediate bearing housing, the second accelerometer is installed inside the propeller hub near the blade root, and the third accelerometer is installed at the four corners of the main engine base. The first flow sensor is installed at the stern of the hull, 2 meters in front of the propeller center, and the second flow sensor is installed at the stern of the hull, 3 meters behind the propeller center. The speed sensor is installed beside the main shaft, opposite the speed measuring gear on the main shaft.

[0062] Regarding the filter parameter settings, the passband frequency range of the first bandpass filter is set to 8Hz to 45Hz to extract low-frequency vibration signals from the intermediate bearing. The passband frequency range of the second bandpass filter is set to 60Hz to 180Hz to extract mid-frequency vibration signals from the propeller. The passband frequency range of the third bandpass filter is set to 220Hz to 480Hz to extract high-frequency vibration signals from the main unit base.

[0063] In the signal processing, this embodiment adopts a synchronous acquisition method, using a clock synchronization module to synchronize the acquisition time of each sensor, ensuring accurate phase relationships between signals. All acquired vibration, flow velocity, and rotational speed signals undergo digital filtering to further eliminate noise interference.

[0064] In the calculation of the coefficient of performance (COP), this embodiment introduces a moving average process. Ten continuously collected velocity difference signals and ten rotational speed difference signals are each subjected to a moving average to obtain the average velocity difference signal and the average rotational speed difference signal. The COP is then obtained by dividing the average velocity difference signal by the average rotational speed difference signal. This moving average process reduces the impact of instantaneous fluctuations on the COP calculation and improves the stability of the COP.

[0065] In the process of generating the control signal, this embodiment adopts an adaptive adjustment method. Based on the current navigation status and sea conditions of the ship, the coefficients of each multiplier are automatically adjusted to keep the amplitude of the control signal within a reasonable range. When sea conditions are severe and vibrations are intense, the amplitude of the control signal is appropriately increased to improve vibration suppression; when sea conditions are good and vibrations are minimal, the amplitude of the control signal is appropriately decreased to reduce energy consumption.

[0066] The first piezoelectric actuator includes a first piezoelectric stack, a first flexible hinge, and a first output push rod. One end of the first piezoelectric stack is fixedly connected to the first end of the first flexible hinge, and the second end of the first flexible hinge is fixedly connected to one end of the first output push rod. The other end of the first output push rod abuts against the housing of the intermediate bearing. When a first control signal is applied to the first piezoelectric stack, the first piezoelectric stack undergoes expansion and contraction deformation, which is transmitted to the first output push rod through the first flexible hinge, causing displacement of the intermediate bearing housing and suppressing vibration at the intermediate bearing. The first flexible hinge has a flexible amplification function, which can amplify the small displacement of the first piezoelectric stack into a larger output displacement.

[0067] The second piezoelectric actuator includes a second piezoelectric stack, a second flexible hinge, and a second output push rod. One end of the second piezoelectric stack is fixedly connected to the first end of the second flexible hinge, and the second end of the second flexible hinge is fixedly connected to one end of the second output push rod. The other end of the second output push rod abuts against the inner wall of the propeller hub. When a second control signal is applied to the second piezoelectric stack, the second piezoelectric stack undergoes expansion and contraction deformation, which is transmitted to the second output push rod through the second flexible hinge, causing displacement of the inner wall of the propeller hub and thus suppressing vibration at the propeller.

[0068] The third piezoelectric actuator includes a third piezoelectric stack, a third flexible hinge, and a third output push rod. One end of the third piezoelectric stack is fixedly connected to the first end of the third flexible hinge, the second end of the third flexible hinge is fixedly connected to one end of the third output push rod, and the other end of the third output push rod abuts against the base of the ship's main engine. When a third control signal is applied to the third piezoelectric stack, the third piezoelectric stack undergoes expansion and contraction deformation, which is transmitted to the third output push rod through the third flexible hinge, causing displacement of the main engine base and suppressing vibration at the main engine base.

[0069] The longitudinal vibration damping device consists of four hydraulic cylinders: a first hydraulic cylinder, a second hydraulic cylinder, a third hydraulic cylinder, and a fourth hydraulic cylinder. These four cylinders are evenly distributed along the circumference of the main shaft and are fixed to the center of the four support columns of a cross-shaped support plate. The cross-shaped support plate is located between the inner ring of the first permanent magnet and the outer ring of the second permanent magnet. The first permanent magnet is mounted on the outer side of the thrust bearing housing, and the second permanent magnet is mounted on the outer side of the main shaft. The front end of the metal push rod of each hydraulic cylinder is fixedly connected to the coil, and the rear end of the metal push rod is fixedly connected to the piston rod of the hydraulic cylinder. When longitudinal vibration occurs in the propulsion shaft system, the metal push rods of the four hydraulic cylinders move synchronously, driving the four coils to reciprocate in the magnetic field, generating an induced current. The induced current generated by the four coils is input into four rectifier circuits for rectification, and the rectified DC power is connected in parallel to the battery for storage.

[0070] The hydraulic controller controls the opening of the first solenoid valve (installed on the oil inlet line of the first hydraulic cylinder) according to a first control signal; it controls the opening of the second solenoid valve (installed on the oil inlet line of the second hydraulic cylinder) according to a second control signal; it controls the opening of the third solenoid valve (installed on the oil inlet line of the third hydraulic cylinder) according to a third control signal; and it controls the opening of the fourth solenoid valve (installed on the oil inlet line of the fourth hydraulic cylinder) according to the weighted average of the first, second, and third control signals. By adjusting the opening of the four solenoid valves, the hydraulic oil flow to the four hydraulic cylinders is controlled, causing the four hydraulic cylinders to generate a thrust opposite to the vibration direction, thereby actively suppressing longitudinal vibration.

[0071] The display unit uses a touch-screen LCD display, with an energy efficiency coefficient display area, a first vibration waveform display area, a second vibration waveform display area, a third vibration waveform display area, and a parameter setting area. Operators can set preset speed settings, frequency ranges for each bandpass filter, and amplification factors for each power amplifier through the parameter setting area. The display unit updates the energy efficiency coefficient display area in real time based on the received energy efficiency coefficient, and plots the first vibration waveform curve based on the first filtered signal, the second vibration waveform curve based on the second filtered signal, and the third vibration waveform curve based on the third filtered signal. When the amplitude of any vibration waveform exceeds a preset alarm threshold, the display unit issues an audible and visual alarm signal to alert the operator.

[0072] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for vibration suppression and energy efficiency improvement of a marine propulsion system, characterized in that, The marine propulsion system includes a propulsion shafting system, a main engine, and a propeller. The propulsion shafting system includes a main shaft, a coupling, and an intermediate bearing. One end of the main shaft is connected to the output end of the main engine via the coupling. The middle part of the main shaft is rotatably connected to the intermediate bearing. The other end of the main shaft is connected to the propeller. The method includes the following steps: Step a: Collect the first vibration signal at the intermediate bearing of the propulsion shaft system, collect the second vibration signal inside the propeller hub, and collect the third vibration signal at the base of the ship's main engine. Step b: Collect the first flow velocity signal in front of the propeller, collect the second flow velocity signal behind the propeller, and collect the rotational speed signal of the main shaft of the propulsion shaft system; Step c: Perform bandpass filtering on the first vibration signal to obtain a first filtered signal, perform bandpass filtering on the second vibration signal to obtain a second filtered signal, and perform bandpass filtering on the third vibration signal to obtain a third filtered signal; Step d: Calculate the difference between the first flow velocity signal and the second flow velocity signal to obtain the flow velocity difference signal; calculate the difference between the rotational speed signal and the preset rotational speed setting value to obtain the rotational speed difference signal; calculate the ratio of the flow velocity difference signal to the rotational speed difference signal to obtain the energy efficiency coefficient. Step e: Multiply the first filtered signal by the energy efficiency coefficient to obtain a first control signal, multiply the second filtered signal by the energy efficiency coefficient to obtain a second control signal, and multiply the third filtered signal by the energy efficiency coefficient to obtain a third control signal; Step f: Output the first control signal to the first piezoelectric actuator, output the second control signal to the second piezoelectric actuator, and output the third control signal to the third piezoelectric actuator; Step g: When the propulsion shaft system vibrates longitudinally, the induced current generated by the reciprocating motion of the coil driven by the metal push rod between the first permanent magnet and the second permanent magnet is rectified and stored in the battery. Step h: Output the electrical energy stored in the battery to the hydraulic controller, and control the hydraulic oil flow of the hydraulic cylinder according to the first control signal, the second control signal and the third control signal. Step i: Output the energy efficiency coefficient, the first filter signal, the second filter signal, and the third filter signal to the display unit.

2. The method for vibration suppression and energy efficiency improvement of a marine propulsion system according to claim 2, characterized in that, Step c, bandpass filtering of the first vibration signal, includes: transmitting the first vibration signal to the input of a first charge amplifier via a first shielded cable; amplifying the first vibration signal via the first charge amplifier; transmitting the amplified first vibration signal to the input of a first bandpass filter via a first signal line; and performing bandpass filtering on the amplified first vibration signal via the first bandpass filter to filter out signal components with frequencies lower than a first lower limit frequency and higher than a first upper limit frequency, thereby obtaining the first filtered signal. Bandpass filtering of the second vibration signal includes: transmitting the second vibration signal to the input of a second charge amplifier via a second shielded cable; amplifying the second vibration signal via the second charge amplifier; transmitting the amplified second vibration signal to the input of a second bandpass filter via a second signal line; and performing bandpass filtering on the amplified second vibration signal via the second bandpass filter to filter out signal components with frequencies lower than a second lower limit frequency and higher than a second upper limit frequency, thereby obtaining the second filtered signal. Bandpass filtering of the third vibration signal includes: transmitting the third vibration signal to the input of a third charge amplifier via a third shielded cable; amplifying the third vibration signal via the third charge amplifier; transmitting the amplified third vibration signal to the input of a third bandpass filter via a third signal line; and performing bandpass filtering on the amplified third vibration signal via the third bandpass filter to filter out signal components with frequencies lower than a third lower limit frequency and higher than a third upper limit frequency, thereby obtaining the third filtered signal.

3. The method for vibration suppression and energy efficiency improvement of a marine propulsion system according to claim 3, characterized in that, Step d, calculating the difference between the first flow velocity signal and the second flow velocity signal, includes: transmitting the first flow velocity signal to the input terminal of the first analog-to-digital converter (ADC) via a fourth shielded cable; performing analog-to-digital conversion on the first flow velocity signal using the first ADC; transmitting the converted first flow velocity signal to the first input terminal of the first subtractor via a fourth signal line; transmitting the second flow velocity signal to the input terminal of the second ADC via a fifth shielded cable; performing analog-to-digital conversion on the second flow velocity signal using the second ADC; transmitting the converted second flow velocity signal to the second input terminal of the first subtractor via a fifth signal line; performing a subtraction operation on the converted first flow velocity signal and the converted second flow velocity signal using the first subtractor; and subtracting the converted second flow velocity signal from the converted first flow velocity signal to obtain the flow velocity difference signal. Calculating the difference between the speed signal and the preset speed setting value includes: transmitting the speed signal to the input terminal of the third analog-to-digital converter through the sixth shielded cable; performing analog-to-digital conversion on the speed signal through the third analog-to-digital converter; transmitting the converted speed signal to the first input terminal of the second subtractor through the sixth signal line; transmitting the preset speed setting value to the second input terminal of the second subtractor through the seventh signal line; performing a subtraction operation between the converted speed signal and the preset speed setting value through the second subtractor; and subtracting the preset speed setting value from the converted speed signal to obtain the speed difference signal. Calculating the ratio of the flow velocity difference signal to the rotational speed difference signal includes: transmitting the flow velocity difference signal to the first input terminal of the divider through the eighth signal line, transmitting the rotational speed difference signal to the second input terminal of the divider through the ninth signal line, performing a division operation on the flow velocity difference signal and the rotational speed difference signal through the divider, and dividing the flow velocity difference signal by the rotational speed difference signal to obtain the energy efficiency coefficient.

4. The method for vibration suppression and energy efficiency improvement of a marine propulsion system according to claim 1, characterized in that, Step e, multiplying the first filtered signal with the energy efficiency coefficient, includes: transmitting the first filtered signal to the first input terminal of the first multiplier through the tenth signal line, transmitting the energy efficiency coefficient to the second input terminal of the first multiplier through the eleventh signal line, performing a multiplication operation on the first filtered signal and the energy efficiency coefficient through the first multiplier, and multiplying the first filtered signal by the energy efficiency coefficient to obtain the first control signal; Multiplying the second filtered signal with the energy efficiency coefficient includes: transmitting the second filtered signal to the first input terminal of the second multiplier through the twelfth signal line, transmitting the energy efficiency coefficient to the second input terminal of the second multiplier through the thirteenth signal line, performing a multiplication operation on the second filtered signal and the energy efficiency coefficient through the second multiplier, and multiplying the second filtered signal by the energy efficiency coefficient to obtain the second control signal; Multiplying the third filtered signal with the energy efficiency coefficient includes: transmitting the third filtered signal to the first input terminal of the third multiplier through the fourteenth signal line, transmitting the energy efficiency coefficient to the second input terminal of the third multiplier through the fifteenth signal line, performing a multiplication operation on the third filtered signal and the energy efficiency coefficient through the third multiplier, and multiplying the third filtered signal by the energy efficiency coefficient to obtain the third control signal.

5. The method for vibration suppression and energy efficiency improvement of a marine propulsion system according to claim 1, characterized in that, Step f, which involves outputting the first control signal to the first piezoelectric actuator, includes: transmitting the first control signal to the input terminal of the first power amplifier via the sixteenth signal line; amplifying the first control signal via the first power amplifier; transmitting the amplified first control signal to the input terminal of the first piezoelectric actuator via the seventeenth signal line; and generating a first displacement based on the amplified first control signal, wherein the direction of the first displacement is perpendicular to the axis of the main shaft. Outputting the second control signal to the second piezoelectric actuator includes: transmitting the second control signal to the input terminal of the second power amplifier through the eighteenth signal line; amplifying the second control signal through the second power amplifier; transmitting the amplified second control signal to the input terminal of the second piezoelectric actuator through the nineteenth signal line; and generating a second displacement amount according to the amplified second control signal, wherein the direction of the second displacement amount is parallel to the axis of the propeller. Outputting the third control signal to the third piezoelectric actuator includes: transmitting the third control signal to the input terminal of the third power amplifier through the twentieth signal line; amplifying the third control signal through the third power amplifier; transmitting the amplified third control signal to the input terminal of the third piezoelectric actuator through the twentieth signal line; and generating a third displacement based on the amplified third control signal, wherein the direction of the third displacement is perpendicular to the base plane of the ship's main engine.

6. The method for vibration suppression and energy efficiency improvement of a marine propulsion system according to claim 1, characterized in that, The first piezoelectric actuator includes a first piezoelectric stack, a first flexible hinge, and a first output push rod. One end of the first piezoelectric stack is fixedly connected to the first end of the first flexible hinge, the second end of the first flexible hinge is fixedly connected to one end of the first output push rod, and the other end of the first output push rod abuts against the housing of the intermediate bearing. The second piezoelectric actuator includes a second piezoelectric stack, a second flexible hinge, and a second output push rod. One end of the second piezoelectric stack is fixedly connected to the first end of the second flexible hinge, the second end of the second flexible hinge is fixedly connected to one end of the second output push rod, and the other end of the second output push rod abuts against the inner wall of the propeller hub. The third piezoelectric actuator includes a third piezoelectric stack, a third flexible hinge, and a third output push rod. One end of the third piezoelectric stack is fixedly connected to the first end of the third flexible hinge, the second end of the third flexible hinge is fixedly connected to one end of the third output push rod, and the other end of the third output push rod abuts against the base of the ship's main engine.

7. The method for vibration suppression and energy efficiency improvement of a marine propulsion system according to claim 1, characterized in that, The system comprises four hydraulic cylinders, namely, a first hydraulic cylinder, a second hydraulic cylinder, a third hydraulic cylinder, and a fourth hydraulic cylinder. The four hydraulic cylinders are evenly distributed along the circumference of the main shaft. Each of the four hydraulic cylinders is fixed to the middle of the four support columns of the cross-shaped support plate. The cross-shaped support plate is located between the inner ring of the first permanent magnet and the outer ring of the second permanent magnet. The first permanent magnet is installed on the outside of the thrust bearing seat ring, and the second permanent magnet is installed on the outside of the main shaft. The front end of the metal push rod is fixedly connected to the coil, and the rear end of the metal push rod is fixedly connected to the piston rod of the hydraulic cylinder.

8. The method for vibration suppression and energy efficiency improvement of a marine propulsion system according to claim 1, characterized in that, The passband frequency range of the first bandpass filter is set to 5Hz to 50Hz. The first bandpass filter attenuates signal components with frequencies below 5Hz and above 50Hz, and retains signal components with frequencies in the range of 5Hz to 50Hz. The passband frequency range of the second bandpass filter is set to 50Hz to 200Hz. The second bandpass filter attenuates signal components with frequencies below 50Hz and above 200Hz, and retains signal components with frequencies in the range of 50Hz to 200Hz. The passband frequency range of the third bandpass filter is set to 200Hz to 500Hz. The third bandpass filter attenuates signal components with frequencies below 200Hz and above 500Hz, and retains signal components with frequencies in the range of 200Hz to 500Hz.

9. The method for vibration suppression and energy efficiency improvement of a marine propulsion system according to claim 1, characterized in that, Step g, which involves rectifying the induced current generated by the reciprocating motion of the coil driven by the metal push rod between permanent magnets No. 1 and No. 2 and storing it in the battery, includes: connecting the two ends of the coil to the AC input terminal of the rectifier circuit via the 22nd and 23rd signal lines; performing full-wave rectification on the induced current generated by the coil via the rectifier circuit; outputting the rectified DC power to the positive terminal of the battery via the 24th signal line; grounding the negative terminal of the battery via the 25th signal line; and connecting a filter capacitor in parallel between the positive and negative terminals of the battery, with one end of the filter capacitor connected to the positive terminal of the battery and the other end connected to the negative terminal of the battery.

10. The method for vibration suppression and energy efficiency improvement of a marine propulsion system according to claim 10, characterized in that, Step h, which involves outputting the electrical energy stored in the battery to the hydraulic controller, includes: connecting the positive terminal of the battery to the positive power input terminal of the hydraulic controller via a 26th signal line, and connecting the negative terminal of the battery to the negative power input terminal of the hydraulic controller via a 27th signal line; controlling the opening of the first solenoid valve according to the first control signal, the opening of the second solenoid valve according to the second control signal, and the opening of the third solenoid valve according to the third control signal, wherein the first solenoid valve is installed on the oil inlet pipe of the first hydraulic cylinder, the second solenoid valve is installed on the oil inlet pipe of the second hydraulic cylinder, and the third solenoid valve is installed on the oil inlet pipe of the third hydraulic cylinder; Step i, which involves outputting the energy efficiency coefficient, the first filtered signal, the second filtered signal, and the third filtered signal to the display unit, includes: outputting the energy efficiency coefficient to the first display input terminal of the display unit via the twenty-eighth signal line; outputting the first filtered signal to the second display input terminal of the display unit via the twenty-ninth signal line; outputting the second filtered signal to the third display input terminal of the display unit via the thirtieth signal line; and outputting the third filtered signal to the fourth display input terminal of the display unit via the thirty-first signal line. The display unit displays the current energy efficiency value based on the energy efficiency coefficient, displays a first vibration waveform based on the first filtered signal, displays a second vibration waveform based on the second filtered signal, and displays a third vibration waveform based on the third filtered signal.

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