Intelligent tail shaft sealing device

Abstract

An intelligent tail shaft sealing device comprises a tail shaft sealing ring, a tail shaft lubricating oil pipe, a tail shaft lubricating oil pump, a tail shaft oil cabinet, a lubricating oil sealing cavity, an air cavity, a tail shaft pipe cavity, an air flow control valve, a lubricating oil flow control valve and an intelligent controller. The air flow control valve is used for controlling the flow of air entering the air chamber so as to keep the pressure difference between the air chamber and seawater constant; the lubricating oil flow control valve is used for controlling the constant lubricating oil flow from the lubricating oil pump to the lubricating oil sealing chamber; the intelligent controller receives various pressure signals and sends out control signals through the main control chip, so that the opening degree of the air flow control valve and the opening degree of the lubricating oil flow control valve are controlled. According to the device, through the arrangement of the intelligent control circuit, various pressure flow signals are sensed in time, the control valve is adjusted in real time by processing and calculating the signals, abrasion of a tail shaft sealing ring is reduced, and leakage of lubricating oil is prevented.

Description

Technical Field

[0001] The present invention relates to a stern shaft sealing device for a ship, and in particular to an intelligent stern shaft sealing device. Background Art

[0002] The stern shaft, also known as the tail shaft, is the last shaft in a ship's shafting system. The operating conditions of a ship's stern shaft seal are extremely harsh. In addition to being subjected to severe wear, friction, and high temperatures, it is also subject to the effects of silt-laden water in oceans and rivers. On large ships with a deep draft, the stern shaft seal must also withstand the pressure difference between the outboard water pressure and the lubricating oil pressure. The propeller's rotation creates cantilever and uneven loads, causing radial runout and eccentric vibration in the stern shaft. When the ship is reversing, the stern shaft also experiences a certain amount of lateral vibration. These harsh operating conditions can easily cause operational failures in a ship's stern shaft seal. Failure of the stern shaft seal not only allows large amounts of seawater to intrude into the stern tube, accelerating damage to the stern tube and stern bearing, but also causes lubricating oil leakage, polluting the ocean.

[0003] Current mainstream stern seals can be categorized into three main types, based on their sealing method: oil seals, water seals, and gas seals. The most representative technology is Japan's AIR GUARD 3AS stern seal, which combines the advantages of oil, water, and gas seals, achieving superior performance compared to traditional Simplex seals. This improves the stern seal's operating environment in good sea conditions and when the ship's draft changes slowly, extending its service life. However, in adverse or even severe sea conditions, the seal, which uses changes in air pressure to transmit a signal to the mechanical pressure regulating valve to control air flow, exhibits significant response lag. This results in the valve's controlled air flow not matching the actual seawater pressure, causing severe wear on the stern seal and, in severe cases, stern tube oil leakage, contaminating the marine environment. Furthermore, this type of equipment is difficult to commission and maintain. Utility Model Content

[0004] Based on the AIR GUARD 3AS stern shaft seal, this device adds an intelligent air valve adjustment and alarm circuit that can respond automatically and promptly. This keeps the distance between the stern shaft seal ring and the wear-resistant bushing constant while maintaining a stable flow rate in the seal ring lubricating oil sealing chamber. This reduces the wear of the stern shaft seal ring and lip seal ring, and extends the service life of the stern shaft seal.

[0005] The technical solution adopted by this device is:

[0006] An intelligent stern shaft sealing device, comprising a stern shaft sealing ring, a stern shaft lubricating oil pipe, a stern shaft lubricating oil pump, a lubricating oil tank, a lubricating oil sealing chamber, an air chamber, a stern shaft tube chamber, a servo motor, an air flow control valve, a lubricating oil flow control valve, a pressure sensor, and an intelligent controller. The stern shaft lubricating oil pipe comprises a first lubricating oil pipe and a second lubricating oil pipe arranged in parallel and connected to the lubricating oil tank. The first lubricating oil pipe is connected to the stern shaft tube chamber, and the second lubricating oil pipe is connected to the lubricating oil sealing chamber. The air flow control valve controls the air flow entering the air chamber via the servo motor to maintain a constant pressure differential between the air chamber and seawater. The lubricating oil flow control valve is disposed on the first lubricating oil pipe and is used to control the flow of lubricating oil from the lubricating oil tank to the lubricating oil sealing chamber.

[0007] The intelligent controller receives various pressure and flow signals and sends a control signal through the main control chip to control the opening of the air flow control valve. The intelligent controller includes:

[0008] a measuring unit, the measuring unit comprising a seawater pressure sensor for detecting external seawater pressure, a pressure sensor for detecting air pressure in the air chamber, and a flow sensor for detecting air and oil flow rates;

[0009] The main control chip is used to obtain the difference of the pressure signal and output the control signal for controlling the opening of the air flow control valve after calculation;

[0010] The execution unit is used to adjust the opening of the air flow control valve and the lubricating oil flow control valve in real time according to the control signal, so that the differences between seawater pressure, air pressure and lubricating oil pressure are maintained within the set thresholds.

[0011] The stern shaft sealing ring includes front and rear sealing rings, the rear sealing ring includes a first sealing ring, a second sealing ring, and a third sealing ring, which are used to isolate the stern shaft tube lubricating oil and seawater; the front sealing ring includes a fourth sealing ring and a fifth sealing ring, which are used to isolate the lubricating oil and prevent it from leaking into the engine room; the air chamber is arranged between the first and second sealing rings, the lubricating oil sealing chamber is arranged between the second and third sealing rings, and the stern shaft tube chamber is arranged between the third and fourth sealing rings.

[0012] The stern shaft lubricating oil pipe further includes a third lubricating oil pipe, and the third lubricating oil pipe is used to transport the lubricating oil flowing back from the stern shaft tube chamber to the lubricating oil tank.

[0013] The air pressure sensor is arranged in the air chamber.

[0014] The lubricating oil flow sensor is arranged on the second lubricating oil pipe.

[0015] The measuring unit is electrically connected to the signal transmitting unit, which is used to convert the pressure signal or flow signal obtained by the sensor into a standard electrical signal and transmit the electrical signal to the main control chip.

[0016] The main control chip is also electrically connected to a step-down power supply unit, which is used to reduce the voltage of an external power supply to the operating voltage of the main control chip and provide a stable power supply to the main control chip.

[0017] The intelligent controller further comprises an alarm, which is used to issue an alarm when the air flow value or the lubricating oil flow value exceeds a set threshold.

[0018] The main control chip model is STC15W4K48S4.

[0019] The beneficial effects of this device are as follows: through the setting of the intelligent controller, the stern shaft sealing device can timely sense the air pressure signal, seawater pressure signal and lubricating oil flow signal, and adjust the air flow control valve in real time by processing and calculating the signals, thereby preventing lubricating oil from leaking from the sealing ring under harsh navigation conditions, reducing the risk of seawater backflow into the stern shaft sealing device, and at the same time reducing the loss of the stern shaft sealing ring. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the functional modules of the intelligent control circuit in the intelligent stern shaft sealing device.

[0021] Figure 2 This is a structural diagram of the intelligent air stern shaft sealing device.

[0022] Figure 3 This is a schematic diagram of the pressure of the stern shaft sealing ring and each chamber of this device.

[0023] Figure 4 Working diagram of the first sealing ring.

[0024] Figure 5 Schematic diagram of the functional modules of the main control chip.

[0025] Figure 6 This is the control circuit diagram of the main control chip.

[0026] Figure 7 This is the circuit diagram of the signal transmission unit.

[0027] Figure 8 This is the circuit diagram of the step-down power supply unit.

[0028] Figure 9 This is the circuit diagram of the execution unit.

[0029] Figure 10 Wiring diagram of the air flow sensor.

[0030] Figure 11 Circuit diagram of the alarm.

[0031] In the figure: a measuring unit 10; a signal transmitting unit 20; a main control chip 30; a step-down power supply unit 40; and an execution unit 50. DETAILED DESCRIPTION

[0032] Currently, the most classic air stern seal is the AIRGUARD 3AS. This classic AIRGUARD 3AS air stern seal uses a mechanical pressure regulating valve to control the air and oil flow, maintaining an appropriate gap between the stern seal ring and the stern sleeve, thereby reducing wear on the stern seal ring and extending its service life.

[0033] However, in complex and even harsh marine environments, the sensing and regulation of traditional mechanical pressure regulating structures exhibit hysteresis, which can easily cause the air pressure, lubricating oil pressure, and external seawater pressure within the seal to be unstable, leading to oil leakage and severe wear of the seal ring. Therefore, this device is equipped with an intelligent control circuit to maintain the air pressure, seawater pressure, and lubricating oil pressure within the stern shaft seal as constant as possible, preventing oil leakage while further delaying wear of the seal ring.

[0034] The device includes a stern tube lubricating oil pipe, a stern shaft lubricating oil pump, a lubricating oil cabinet, a lubricating oil sealing chamber, an air chamber, a stern tube chamber, a lubricating oil flow control valve and an intelligent controller. Figure 1 The intelligent controller includes a main control chip 30, a measuring unit 10, a signal transmitting unit 20, a step-down power supply unit 40 and an execution unit 50.

[0035] The measurement unit 10 includes a seawater pressure sensor, an air pressure sensor, an air flow sensor, and an oil flow sensor. The air pressure sensor is located in the air chamber, the seawater pressure sensor is located on the outer surface of the stern shaft seal, the air flow sensor is located behind the air flow control valve, and the oil flow sensor is located on the second oil pipe.

[0036] like Figure 2 、 Figure 3The stern shaft oil pipe includes a first, second, and third oil pipes arranged in parallel and connected to the oil tank. The first and third oil pipes communicate with the oil seal chamber, while the second oil pipe communicates with the stern tube chamber. The oil flow control valve is located on the first oil pipe. The stern shaft seal ring includes front and rear seal rings. The rear seal ring includes the first, second, and third seal rings, which are used to isolate the stern tube oil from seawater. The front seal ring includes the fourth and fifth seal rings, which are used to isolate the oil and prevent it from leaking into the engine room. The air chamber is located between the first and second seal rings, the oil seal chamber is located between the second and third seal rings, and the stern tube chamber is located between the third and fourth seal rings.

[0037] In case of sudden severe sea conditions, it is often difficult to quickly adjust the air pressure in the air chamber to maintain it at 0.2 bar with the external seawater pressure. There is a risk that seawater will flow back into the air chamber formed by the first and second sealing rings. In this environment, the wear of the sealing ring components will be more serious than in normal working conditions. In order to maintain the sealing state of the stern shaft and extend the service life of the sealing ring components, such as Figure 4 The intelligent controller can be used to control air flow in real time. Its operating principle is as follows: pressure sensors in the measuring unit 10 are installed in both the air chamber and the seawater outside the ship's side, constantly monitoring pressure changes within each chamber. The pressure signals measured by the air and seawater pressure sensors in the measuring unit 10 are converted into standard 4-20mA electrical signals and transmitted to the main control chip 30. The main control chip 30 calculates the control variable of the air flow control valve based on proportional-integral-differential (PID) calculations, and then controls the opening of the air flow control valve through the control execution unit 50. Due to the rapid response of the device signal and the rapid control of the main control chip 30, the air flow control valve can quickly adjust its opening in response to changes in the ship's draft, thereby maintaining the pressure difference between the air pressure inside the first seal ring and the external seawater pressure at 0.2 bar. This ensures that the distance h between the first seal ring and the wear-resistant bushing remains constant, significantly reducing the wear rate of the first seal ring and extending the service life of the seal ring component.

[0038] Intelligent controllers can also be used to regulate oil flow. Figure 2Oil is pumped from the oil tank through the first oil pipe into the oil seal chamber formed by the second and third seal rings via the stern oil pump. Then, it is fed through the second oil pipe into the stern tube chamber formed by the third and fourth seal rings. The oil in the stern tube chamber then returns to the oil tank through the third oil pipe, completing the oil circulation throughout the entire oil pipeline. This integrated oil circulation maintains a constant flow of oil throughout the entire oil pipeline, ensuring that the pressure in the oil seal chamber is 0.4 bar higher than the pressure in the air chamber formed by the first and second seal rings, and 0.2 bar higher than the pressure in the stern tube chamber formed by the third and fourth seal rings. This pressure setting prevents oil leakage from flowing into the air chamber and prevents oil backflow. This stable pressure and flow rate prevents oil leakage from the seal rings and ensures minimal or no wear on the third, fourth, and fifth seal rings, extending the service life of the seal ring components.

[0039] In this device, the lubricating oil pressure signal is obtained by calculating the lubricating oil flow signal. , where G is the oil flow rate, u is a fixed flow coefficient, ∆p is the pressure difference between the oil seal chamber and the air chamber, and F is the opening of the oil flow control valve. When the valve opening is fixed, the oil flow rate G and In this device, air pressure changes are fed back to the oil tank, so the pump inlet and outlet pressures also change by the same amount as the air pressure. This theoretically keeps the pressure difference ∆p between the oil seal chamber and the air chamber constant (in practice, there are slight variations that are negligible). The oil flow rate also remains essentially constant, decreasing only if the filter preceding the oil pump becomes clogged or the oil pump malfunctions. Monitoring the oil flow rate provides a more convenient way to determine the pressure difference between the oil seal chamber and the air pressure.

[0040] like Figure 5 、 Figure 6 The main control chip 30 uses the STC15W4K48S4 microcontroller, which includes a central processing unit (CPU), program memory (Flash), data memory (SRAM), timers / counters, a dedicated power-down wake-up timer, I / O ports, a high-speed A / D converter, a comparator, a watchdog timer, four UART high-speed asynchronous serial communication ports, CCP / PWM / PCA and a high-speed synchronous serial communication port (SPI), an on-chip high-precision RC clock, and a high-reliability reset module. The STC15W4K32S4 series microcontroller incorporates all the necessary modules for data acquisition and control, making it a true system-on-chip. Simply adding two external capacitors and providing a stable low-voltage power supply allows the microcontroller to operate normally.

[0041] In the circuitry of the microcontroller main control chip 30, CN10 is the download interface for program downloads; C12 and C13 are decoupling capacitors for improved interference immunity; LED5 is the operating indicator, and R28 is the current-limiting resistor for the indicator. CN9 is the touchscreen interface, supporting the full range of Taojingchi touchscreens. If needed, a touchscreen can be connected to display system parameters and configuration information. The microcontroller's ADC2 and ADC3 pins are used to acquire conditioned analog signals from pressure transmitters. After acquiring signals from multiple pressure transmitters, the microcontroller calculates the differential pressure and controls the output of a 4-20 mA current signal through pins 42, 43, and 44, corresponding to the three general-purpose digital I / O ports P02 / P03 / P04, respectively. This signal is used to control a circuit consisting of the GP8302-TC50-EW chip and other auxiliary components, thereby controlling the valve opening and achieving a fixed differential pressure.

[0042] like Figure 7 , the signal transmission unit 20 includes a pressure signal transmitter, a Hall current sensor, an RC low-pass filter circuit and a signal amplification circuit. In this device, the pressure signal transmitter is used to detect seawater pressure, air pressure and lubricating oil flow. The Hall current sensor is a sensitive weak current detection and conversion device that can measure current signals of any waveform and convert them into standard DC signal output. As a preferred embodiment of this device, this device uses a Hall current sensor with model ACS712ELCTR-05B-T. Since the working environment of the stern shaft sealing device is located on the seabed, it is easily interfered by high-frequency noise caused by external ocean currents. In order to reduce the high-frequency noise signal in the current signal, an RC low-pass filter circuit is also provided in the circuit. The RC low-pass circuit includes an operational amplifier, a resistor and a capacitor. After filtering, in order to ensure that the main control chip can receive the signal, a signal amplification circuit is also provided in the circuit. The signal amplification circuit includes an operational amplifier and a resistor. In this device, the operational amplifier model used is LMV358.

[0043] Since the operating voltage of the main control chip 30 is 5V, the 24V power supply needs to pass through the step-down power supply unit 40 before it can be connected to the VCC power input port of the main control chip 30. Figure 8 As a preferred option for this device, the external 24V power supply first passes through a reverse polarity protection diode via socket CN1, then is converted to 5V via a π-type filter and the DC-DC chip LM2596-5.0. This power then passes through an LC filter and finally a 0.5A resettable fuse to power various chips in the device that operate at 5V. Chips receiving 5V power include the current sensor chip ACS712ELCTR-05B-T, the operational amplifier LMV358, and the microcontroller STC15W4K48S4.

[0044] like Figure 9 The execution unit 50 includes an air flow meter, an air flow control valve, an oil flow control valve, a servo motor, and a valve opening control circuit. The valve opening control circuit, or the control circuit for the execution unit 50, is used to receive control signals from the main control chip 30 and control the servo motor, thereby controlling the opening of the air flow control valve or the oil flow control valve. The P02, P03, and P04 ports of the main control chip 30 are connected to the valve opening control circuit. The valve opening control circuit includes a digital-to-analog conversion circuit, which includes a GP8302-TC50-EW digital-to-analog conversion chip. The output port IOUT of the digital-to-analog conversion chip is connected to the transistor GL14P04-8. The GP8302-TC50-EW is an I2C signal-to-analog converter, or DAC. This chip can linearly convert the 12-bit digital value 0x000-0xFFF into a 4-20mA analog current, which is then connected to the execution signal input port via a diode and resistor. In this device, the execution signal will eventually be output to the air flow control valve and the oil flow control valve. The digital-to-analog conversion chip and transistor in the valve opening control circuit are powered by a 24V power supply.

[0045] like Figure 10 、 Figure 11 The intelligent controller also includes an alarm, which sounds an alarm when the air or oil flow rate exceeds a set threshold. The main control chip obtains flow information from an external flow meter via the ADC4 interface. After performing calculations and comparisons, it outputs an alarm signal via interface P26 when the flow rate exceeds the set threshold. The alarm signal is rectified and filtered by a transistor and diode, and then converted by a relay into a step signal to control an external alarm device. The alarm circuit uses an S8050-J3Y transistor, a 1N4007 diode, and an HK4100F-DC24V-SDG relay.

[0046] The above describes the main embodiments and advantages of this device. It should be noted that the specific implementation of this device is not limited to the above-mentioned methods. Any non-substantial improvements made using the technical solution of this device, or any direct application of the concept and technical solution of this device to other situations without modification, are all within the scope of protection of this device. The scope of protection claimed for this device is defined by the attached claims and their equivalents.

Claims

1. An intelligent stern shaft sealing device, characterized by: The device includes a stern shaft sealing ring, a stern shaft lubricating oil pipe, a stern shaft lubricating oil pump, a lubricating oil tank, a lubricating oil sealed chamber, an air chamber, a stern shaft tube chamber, a servo motor, an air flow control valve, a lubricating oil flow control valve, a pressure sensor, and an intelligent controller. The stern shaft lubricating oil pipe includes a first lubricating oil pipe and a second lubricating oil pipe arranged in parallel and connected to the lubricating oil tank. The first lubricating oil pipe is connected to the stern shaft tube chamber, and the second lubricating oil pipe is connected to the lubricating oil sealed chamber. The air flow control valve controls the air flow entering the air chamber via a servo motor to maintain a constant pressure difference between the air chamber and seawater. The lubricating oil flow control valve is arranged on the first lubricating oil pipe and is used to control the flow of lubricating oil from the lubricating oil tank to the lubricating oil sealed chamber. The intelligent controller receives various pressure and flow signals and sends a control signal through the main control chip to control the opening of the air flow control valve. The intelligent controller includes: a measuring unit, the measuring unit comprising a seawater pressure sensor for detecting external seawater pressure, a pressure sensor for detecting air pressure in the air chamber, an air flow sensor for detecting air flow, and a lubricating oil flow sensor for detecting lubricating oil flow; The main control chip is used to obtain the difference of the pressure signal and output the control signal for controlling the opening of the air flow control valve after calculation; The execution unit is used to adjust the opening of the air flow control valve in real time according to the control signal, so that the differences between seawater pressure, air pressure and lubricating oil pressure are maintained within the set thresholds.

2. The intelligent stern shaft sealing device according to claim 1, characterized in that: The stern shaft sealing ring includes front and rear sealing rings, the rear sealing ring includes a first sealing ring, a second sealing ring, and a third sealing ring, which are used to isolate the stern shaft tube lubricating oil and seawater; the front sealing ring includes a fourth sealing ring and a fifth sealing ring, which are used to isolate the lubricating oil and prevent it from leaking into the engine room; the air chamber is arranged between the first and second sealing rings, the lubricating oil sealing chamber is arranged between the second and third sealing rings, and the stern shaft tube chamber is arranged between the third and fourth sealing rings.

3. The intelligent stern shaft sealing device according to claim 1, characterized in that: The stern shaft lubricating oil pipe further includes a third lubricating oil pipe, and the third lubricating oil pipe is used to transport the lubricating oil flowing back from the stern shaft tube chamber to the lubricating oil tank.

4. The intelligent stern shaft sealing device according to claim 2, characterized in that: The air pressure sensor is arranged in the air chamber.

5. The intelligent stern shaft sealing device according to claim 1, characterized in that: The lubricating oil flow sensor is arranged on the second lubricating oil pipe.

6. The intelligent stern shaft sealing device according to claim 1, characterized in that: The measuring unit is electrically connected to the signal transmitting unit, which is used to convert the pressure signal or flow signal obtained by the sensor into a standard electrical signal and transmit the electrical signal to the main control chip.

7. The intelligent stern shaft sealing device according to claim 1, characterized in that: The main control chip is also electrically connected to a step-down power supply unit, which is used to reduce the voltage of an external power supply to the operating voltage of the main control chip and provide a stable power supply to the main control chip.

8. The intelligent stern shaft sealing device according to claim 1, characterized in that: The intelligent controller further comprises an alarm, which is used to issue an alarm when the air flow value or the lubricating oil flow value exceeds a set threshold.

9. The intelligent stern shaft sealing device according to claim 1, characterized in that: The main control chip model is STC15W4K48S4.

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