Air type stern shaft sealing system of ship

Abstract

The utility model provides a ship air type tail shaft sealing system which comprises an air control unit, a gravity oil tank unit connected with the air control unit through a first connecting pipeline, and a tail shaft sealing structure connected with the air control unit through a second connecting pipeline. The pressure collecting unit is arranged to collect the air pressure of the system and the draft pressure of the stern shaft, the collected pressure is compared through the controller, and real-time alarming is carried out when pressure deviation occurs in the system; through the arranged switching circuit, when the system has pressure deviation, the air pressure of the system can be controlled through a proportional valve in the switching circuit, so that the pressure deviation fault is eliminated; besides, when the branch where the first throttling valve is located is closed, air can be controlled to be introduced into the gravity oil tank unit through the switching circuit, so that the air pressure of the system is still kept balanced with the seawater pressure, and it is guaranteed that the rubber ring still works in a proper stress state.

Description

Technical Field

[0001] The utility model relates to the technical field of ship stern shaft sealing, in particular to a ship air type stern shaft sealing system. Background Art

[0002] Ships, as an important means of water transportation, undertake more than 90% of the world's total logistics transportation volume. Most ships rely on internal diesel engines to drive the stern shaft to rotate, and the stern shaft drives the propeller installed outside the hull to rotate to provide power for the ship to move forward. Such a structure determines that the hull and the stern shaft need to be sealed and waterproof. In order to better achieve this function, the ship's stern shaft sealing system is also constantly developing and improving. At present, the most used is the air-type stern shaft sealing system. After summarizing the research and use experience of the air-type stern shaft sealing system, we put forward suggestions for upgrading and transforming its shortcomings. The basic principle of the sealing rubber ring stern shaft seal is to use some measures to make the force of the rubber ring holding the stern shaft within a suitable range. This suitable force can meet the sealing requirements without accelerating the wear of the rubber strip. Both gravity type and air type are sealing rubber ring stern shaft sealing systems. In the gravity stern shaft sealing system, the force of the sealing rubber ring holding the stern shaft is equal to the spring force plus the oil gravity minus the draft pressure. The draft pressure here is a variable force that cannot be controlled. Therefore, the force holding the stern shaft also changes with the draft and cannot reach the ideal range. In the air stern shaft sealing system, the force of the sealing rubber ring holding the stern shaft is equal to the spring force plus the draft pressure minus the air pressure. The function of the air system is to ensure that the air pressure is equal to the draft pressure at all times. Therefore, the force of the sealing rubber ring holding the stern shaft is equivalent to only the spring force, and the spring force is basically constant and can be designed to achieve the ideal range. Therefore, the air stern shaft sealing system allows the sealing rubber ring to work in an ideal state. The air stern shaft sealing system mainly consists of five parts: air control unit, gravity oil tank unit, drain unit, flow unit, and draft air pressure balance valve. And this system requires that the balancing valve always has air discharged under any working conditions, that is, the balancing valve is always open (the air pressure is always slightly greater than the draft pressure), but the opening degree will change with the draft. However, the air-type stern shaft sealing system has the following shortcomings: 1. The system cannot realize the pressure deviation alarm (that is, when the equipment fails, the stern shaft draft pressure and air pressure deviate). This system is to achieve pressure balance, only flow alarm, and the flow alarm can only realize serious fault alarm beyond the control range. Minor deviations within the control range cannot be alarmed, making it difficult to detect problems in the system in the early stage; in most cases, after a leak occurs, the system can only be noticed when the liquid level alarm appears in the collection tank. The pressure deviation failure may have occurred for a long time before the leak, and it is difficult to detect because there is no such alarm. 2. The balancing valve is prone to dirt, blockage, and other reasons that cause the system pressure to lose control, and there is no good rescue plan or measure available.First, the minor faults mentioned above cannot be detected in time. Second, even if they are detected, there are no good measures to take. Basically, we can only wait for the fault to develop further and cause water leakage, and then change to a gravity system or dock for repair. 3. When the system has a serious fault and oil or water leakage occurs, it can only be changed to a gravity system. It cannot achieve rebalancing measures after oil or water leakage. The gravity system is an obsolete product and will accelerate the wear of the rubber ring and the white steel sleeve. These shortcomings have affected the use effect of this system. Utility Model Content

[0003] In order to solve the above technical problems, the utility model adds pressure feedback control and pressure difference alarm functions to the original system, and can take timely remedial measures when pressure deviation occurs in the system, so that the air-type stern shaft sealing system is safer and more stable. The specific technical solutions are as follows:

[0004] A ship air-type stern shaft sealing system comprises an air control unit, a gravity oil tank unit connected to the air control unit through a first connecting pipeline, a stern shaft sealing structure connected to the air control unit through a second connecting pipeline, and a residual discharge unit connected to the stern shaft sealing structure through a third connecting pipeline, and further comprises:

[0005] Controller;

[0006] A pressure collection unit, the pressure collection unit is electrically connected to the controller and is used to collect the air cavity gas pressure and the stern shaft draft pressure;

[0007] A switching circuit is electrically connected to the controller, and the switching circuit includes a first stop valve connected to the front end of a first throttle valve in a first connecting pipeline, a proportional valve connected to the first connecting pipeline in parallel with the first throttle valve, and a second stop valve connected to the pipeline at the front end of the proportional valve.

[0008] Preferably, the stern shaft sealing structure is also connected to a balancing valve communicated with seawater.

[0009] Preferably, the pressure acquisition unit comprises a first pressure sensor for acquiring the gas pressure of the air cavity and a second pressure sensor for acquiring the stern shaft draft pressure.

[0010] Preferably, the residual discharge unit includes a residual discharge tank and a flow control subunit connected to the residual discharge tank.

[0011] Preferably, the flow control subunit includes a second throttle valve connected to the residual discharge tank.

[0012] It can be seen from the above technical scheme that the utility model has the following beneficial effects: in the utility model, by setting up a pressure collection unit, the system air pressure and the stern shaft draft pressure are collected respectively, and the collected pressures are compared through the controller, and a real-time alarm is issued when a pressure deviation occurs in the system; through the setting of the switching circuit, when a pressure deviation occurs in the system, the system air pressure can be controlled by the proportional valve in the switching circuit to eliminate the pressure deviation fault so that the system can be balanced again; in addition, the switching circuit can also have the effect of introducing control air into the gravity oil tank unit, that is, when the branch where the first throttle valve is located is closed, the control air can be introduced into the gravity oil tank unit through the switching circuit, so that the air pressure of the system is still balanced with the seawater pressure, ensuring that the rubber ring is still working under a suitable stress state. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is the schematic diagram of the ship's stern shaft sealing system;

[0014] Figure 2 This is a schematic diagram of the upgrading and transformation of the air-type stern shaft sealing system provided by the utility model.

[0015] In the figure: 10, air control unit; 20, first connecting pipeline; 30, gravity oil tank unit; 40, second connecting pipeline; 50, third connecting pipeline; 510, balance valve; 60, residual discharge unit; 610, residual discharge tank; 621, second throttle valve; 70, stern shaft sealing structure; 710, controller; 721, first pressure sensor; 722, second pressure sensor; 731, first stop valve; 732, proportional valve; 733, second stop valve. DETAILED DESCRIPTION

[0016] The following is a detailed description of the present invention in conjunction with the accompanying drawings and specific embodiments. Before describing in detail the technical solutions of each embodiment of the present invention, the nouns and terms involved are explained. In this specification, components with the same name or the same number represent similar or identical structures and are only for illustrative purposes.

[0017] Combine the following Figure 1The air balance in the air-type stern shaft sealing system is analyzed. First, 5-10 bar compressed air is sent to the air control unit, and after being throttled by the throttle valve R10, it is sent to the air cavity between the gravity oil tank unit and the 2# and 3# lip seals. A balance valve is installed on the air cavity to communicate with seawater. Secondly, there is a pipeline in the air cavity leading to the residual unit, which is throttled again by the residual unit through the throttle valve R40 and then discharged to the cabin atmosphere. It can be seen that the air source enters the system after being throttled by the throttle valve R10, and the pressure in the system is controlled by the throttle valve R40 and the balancing valve. The air source pressure and the opening of the throttle valves R10 and R40 are fixed, and the only variable is the opening of the balancing valve. Therefore, the pressure of the entire system is controlled by the opening size of the balancing valve. Further analysis shows that the opening size of the balancing valve is only affected by the seawater pressure. From the analysis of the valve core force, it can be seen that the force on the valve core is equal to the seawater pressure plus the weight of the valve core minus the air pressure minus the spring force minus the friction of the valve core (ignore the friction in the case of a new valve). At a specific moment, the valve core is stationary, that is, the force is zero. Therefore, it means that the ship's draft pressure plus the weight of the valve core plus the spring force is equal to the air pressure. If the weight of the valve core and the spring force are ignored, it means that the draft pressure of this system is always equal to the air pressure. This is the air balance principle of the air stern shaft sealing system.

[0018] In fact, no matter what the working conditions are, the system requires that the balancing valve always discharges air, that is, the balancing valve is always open (the air pressure is always slightly greater than the draft pressure), but the opening degree will change with the draft.

[0019] Therefore, the embodiments of the present invention provide the following technical solutions: Figure 2 A ship air stern shaft sealing system comprises an air control unit 10, a first connecting pipeline 20, a gravity oil tank unit 30, a second connecting pipeline 40, a third connecting pipeline 50, a stern shaft sealing structure 70 and a residual discharge unit 60, wherein the gravity oil tank unit 30 is connected to the air control unit through the first connecting pipeline 20, and the first connecting pipeline 20 is provided with a first throttle valve 210, the first throttle valve is used to adjust the air pressure flowing to the gravity oil tank unit, the stern shaft sealing structure 70 is connected to the air control unit through the second connecting pipeline 40, and the stern shaft sealing structure 70 is also connected to a balancing valve 510 communicated with seawater, the residual discharge unit 60 is connected to the stern shaft sealing structure through the third connecting pipe 50, the residual discharge unit comprises a residual discharge tank 610 and a flow control subunit connected to the residual discharge tank, and the flow control subunit comprises a second throttle valve 621 connected to the residual discharge tank 610.

[0020] In addition, in order to realize pressure feedback and pressure difference alarm for the system, the ship air stern shaft sealing system also includes a controller 710, a pressure collection unit and a switching circuit. Further, the pressure collection unit is electrically connected to the controller, and the pressure collection unit is used to collect the air cavity gas pressure and the stern shaft draft pressure. Further, the pressure collection unit includes a first pressure sensor 721 for collecting the air cavity gas pressure and a second pressure sensor 722 for collecting the stern shaft draft pressure. When in use, the first pressure sensor 721 is connected to the air cavity, and the second pressure sensor 722 is connected to the stern shaft. The switching circuit is also electrically connected to the controller, and the switching circuit includes a first stop valve 731 connected to the first connecting pipeline 20 at the front end of the first throttle valve 210, a proportional valve 732 connected to the first connecting pipeline in parallel with the first throttle valve, and a second stop valve 733 connected to the pipeline at the front end of the proportional valve. When in use, the system air pressure signal and the stern shaft draft pressure signal are collected by the first pressure sensor and the second pressure sensor, and sent to The controller is entered for calculation and comparison to realize real-time alarm of system pressure deviation. By adding a proportional valve 732 in parallel with the first throttle valve in the original system, and installing a first stop valve 731 and a second stop valve 733 before the first throttle valve and the proportional valve, the switching of the two control air is realized. When the system is in normal condition, the first stop valve 731 is opened, the second stop valve 733 is closed, and the system works in the state before the transformation. When pressure deviation occurs due to various reasons, an air pressure deviation alarm can be performed, and then the first stop valve 731 is manually closed and the second stop valve 733 is opened. At this time, the air system will operate under the control of the proportional valve 732 to eliminate the pressure deviation fault and achieve pressure balance again. When the system leaks oil and water, it is necessary to change the original air-type stern shaft sealing system to a gravity-type stern shaft sealing system, close the first stop valve, and open the second stop valve at the same time. At this time, the system provides control air to the gravity oil tank unit through the proportional valve, and the air of the system is still balanced with the seawater pressure, so that the rubber ring still works under a suitable stress state.

[0021] The above-described embodiments are merely descriptions of preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A ship air-type stern shaft sealing system, characterized in that: The invention comprises an air control unit (10), a gravity oil tank unit (30) connected to the air control unit via a first connecting pipeline (20), a stern shaft sealing structure (70) connected to the air control unit via a second connecting pipeline (40), and a residual discharge unit (60) connected to the stern shaft sealing structure (70) via a third connecting pipeline (50), and further comprises: Controller (710); A pressure collection unit, the pressure collection unit is electrically connected to the controller and is used to collect the air cavity gas pressure and the stern shaft draft pressure; A switching circuit is electrically connected to a controller, the switching circuit comprising a first stop valve (731) connected to the front end of a first throttle valve (210) of a first connecting pipeline (20), a proportional valve (732) connected in parallel to the first throttle valve and connected to the first connecting pipeline, and a second stop valve (733) connected to the pipeline at the front end of the proportional valve.

2. The ship air stern shaft sealing system according to claim 1, characterized in that: The stern shaft sealing structure (70) is also connected to a balancing valve (510) that communicates with seawater.

3. The ship air type stern shaft sealing system according to claim 2, characterized in that: The pressure collection unit comprises a first pressure sensor (721) for collecting the gas pressure of the air cavity and a second pressure sensor (722) for collecting the stern shaft draft pressure.

4. The ship air stern shaft sealing system according to claim 3, characterized in that: The residual discharge unit comprises a residual discharge tank (610) and a flow control subunit connected to the residual discharge tank.

5. The ship air stern shaft sealing system according to claim 4, characterized in that: The flow control subunit comprises a second throttle valve (621) connected to the residual discharge tank (610).

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