Rubber choke rod device for inhibiting clearance cavitation of semi-suspension rudder

Abstract

The invention belongs to the technical field of ship anti-cavitation structures, and particularly relates to a rubber choke rod device for restraining clearance cavitation of a semi-suspension rudder. The device is mounted in an annular gap between the inner wall of a socket of a rudder blade of the semi-suspension rudder and the outer wall of a pivot of a rudder horn and comprises two rubber choke rods which are vertically arranged, two ends of each rubber choke rod are connected to the inner wall of the socket of the rudder blade, the rubber choke rods are symmetrical about the middle longitudinal section of the rudder blade, and the outer surfaces of the rubber choke rods are in close contact with the inner wall of the socket and the pivot of the rudder horn. The flexible rubber flow stopping rod is used as a flow stopping device of a core sealing element and is used for directly replacing a mechanical sealing mechanism depending on a precise moving part. According to the device, dynamic change gaps are filled and sealed in a self-adaptive mode through the rubber flow blocking rods by means of the elastic deformation capacity of materials when the rudder blades rotate, so that cavitation generation conditions are eliminated from the physical source, and the self-adaptive capacity of all working conditions is guaranteed while the self-adaptive capacity of all working conditions is guaranteed. And the marine environment adaptability is excellent, the maintenance requirement is extremely low, and the economical efficiency is good.

Description

Technical Field

[0001] This invention belongs to the field of ship anti-cavitation structure technology, and particularly relates to a rubber flow-blocking rod device for suppressing cavitation in the gap of a semi-suspended rudder. Background Technology

[0002] Semi-suspended rudders are one of the mainstream rudder types in modern ships. Their rudder arms are hinged to the hull, and this inherent mechanical connection creates an annular gap between the rudder arm pivot and the rudder blade bearing. When a ship is traveling at medium to high speeds, the high-speed water flow passing through this narrow gap can easily cause the local pressure to drop below the vaporization pressure, leading to severe cavitation. To address this problem, existing solutions mainly follow two technical paths: one is traditional passive optimization, such as local geometric modification of the gap area. These methods can only improve the local flow field environment, and their suppression effect is only for specific navigation conditions, failing to structurally block or eliminate the inherent cavitation source—the gap. The second approach is a more proactive mechanical intervention. For example, using a follow-up mechanical device containing bearings, sleeves, and multiple seals to dynamically seal the gap. While such solutions can theoretically adapt to changes in rudder angle, they rely on bearings and sliding seal mechanisms that require extremely high machining precision, lubrication, and maintenance. In long-term exposure to corrosive and polluted marine environments, they are prone to wear, jamming, or seal failure, significantly limiting their reliability and life-cycle economics. Therefore, existing technologies, whether simple passive protection or complex active mechanisms, have obvious limitations and are difficult to adapt to complex and ever-changing application scenarios. Summary of the Invention

[0003] The purpose of this invention is to provide a new solution that achieves gap sealing from the physical source based on the principle of physical flow obstruction, thereby preventing gap cavitation. This solution effectively suppresses gap cavitation, improves the service life of the semi-suspended rudder, and effectively reduces fluid noise and vibration during the use of the semi-suspended rudder.

[0004] To achieve the above objectives, the present invention adopts the following technical solution.

[0005] A rubber flow-blocking rod device for suppressing cavitation in the gap of a semi-suspended rudder is installed in the annular gap between the inner wall of the bearing socket of the semi-suspended rudder blade and the outer wall of the pivot of the rudder arm. It includes two vertically arranged rubber flow-blocking rods, both ends of which are connected to the inner wall of the bearing socket of the rudder blade and are symmetrical about the longitudinal section of the rudder blade. The outer surface of the rubber flow-blocking rod is in close contact with the inner wall of the bearing socket and the pivot of the rudder arm.

[0006] In a further improved or preferred embodiment of the aforementioned rubber baffle rod device for suppressing cavitation in the semi-suspended rudder gap, the Shore hardness of the rubber baffle rod is A50~A80.

[0007] In a further improved or preferred embodiment of the aforementioned rubber flow-blocking rod device for suppressing cavitation in the semi-suspended rudder clearance, the rubber flow-blocking rod has a circular or elliptical cross-section, and both ends of the rubber flow-blocking rod are rotatably connected to the upper and lower inner walls of the rudder blade bearing socket, with corresponding mounting cavities provided on the upper and lower inner walls of the rudder blade bearing socket; the rubber flow-blocking rod and the rudder arm pivot are in rolling compression contact.

[0008] In a further improved or preferred embodiment of the aforementioned rubber flow-blocking rod device for suppressing cavitation in the semi-suspended rudder clearance, the rubber flow-blocking rod includes a central connecting shaft and a rubber layer disposed outside the connecting shaft; both ends of the connecting shaft are inserted into mounting cavities correspondingly disposed on the upper and lower inner walls of the rudder blade bearing socket.

[0009] In a further improvement or preferred embodiment of the aforementioned rubber baffle rod device for suppressing cavitation in the semi-suspended rudder gap, both ends of the connecting shaft are connected to the mounting cavity via rotary bearings.

[0010] In a further improved or preferred embodiment of the aforementioned rubber baffle rod device for suppressing cavitation in the semi-suspended rudder clearance, the rubber baffle rod has a circular or elliptical cross-section, and both ends of the rubber baffle rod are fixedly connected to the upper and lower inner walls of the rudder blade bearing socket; the rubber baffle rod and the rudder arm pivot are in sliding and compressive contact.

[0011] In a further improvement or preferred embodiment of the aforementioned rubber flow-blocking rod device for suppressing cavitation in the semi-suspended rudder clearance, the upper and lower sides of the inner wall of the rudder bearing socket are provided with mounting grooves, and the end of the rubber flow-blocking rod is provided with an enlarged anchor head or embedded with a metal core and is fixed in the mounting groove by a high-strength adhesive and a mechanical pressure plate.

[0012] Its beneficial effects are as follows:

[0013] This invention proposes a flow-blocking device using a flexible rubber flow-blocking rod as the core sealing element, directly replacing mechanical seal mechanisms that rely on precision moving parts. This device utilizes a rubber flow-blocking rod with specific mechanical properties, leveraging the material's elastic deformation capability to adaptively fill and seal dynamically changing gaps as the rudder blade rotates, thereby eliminating the conditions for cavitation at their physical source. This invention further aims to achieve significant structural simplification, excellent environmental tolerance, extremely low maintenance requirements, and good compatibility with existing rudder systems.

[0014] The proposed solution should focus on a highly simplified structure, ensuring adaptability under all operating conditions while also possessing excellent adaptability to marine environments, extremely low maintenance requirements, and good economic efficiency. Attached Figure Description

[0015] Figure 1 This is a perspective view of the installation structure of a rubber flow-damping rod device used to suppress cavitation in the semi-suspended rudder clearance;

[0016] Figure 2 This is a top view of the installation structure of a rubber flow-damping rod device used to suppress cavitation in the semi-suspended rudder clearance. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0018] The following describes specific embodiments of the rubber flow-blocking rod device in accordance with the principles of this invention. Those skilled in the art should understand that this description is intended to illustrate the implementation of this invention and does not constitute a limitation on the scope of protection.

[0019] like Figure 1 , Figure 2 As shown, when implementing this invention, necessary structural processing is required on both sides of the inner wall of the rudder blade bearing socket, symmetrical about the longitudinal section of the rudder, to form a fixed base for the rubber flow deflector. Typically, a mounting groove is machined at the corresponding position. The shape and size of this mounting groove must match the design of the rubber flow deflector end and ensure the strength of the fixing structure.

[0020] The specific implementation mainly includes two key steps: the preparation and installation of the rubber flow-blocking rod. As a preferred method, the rubber flow-blocking rod is made of special synthetic rubber with the required properties, integrally molded into a closed annular body, typically with a circular or elliptical cross-section. For ease of installation and use, a rigid support shaft can be embedded within the rod body, and both ends of the rod body can be integrally embedded with a metal core or form enlarged anchor heads during molding, depending on the selected rotatable or fixed connection method.

[0021] (I) Installation Method Examples

[0022] a. Fixed connection

[0023] One end of the rubber choke bar is coated with a high-strength adhesive and then embedded into the mounting groove on one side of the rudder blade bearing socket. A mechanical clamp and bolts are used to secure this end, ensuring a reliable connection. Subsequently, the rubber choke bar is arranged around the rudder arm pivot, and its other end is fixed to the mounting groove on the opposite side in the same manner. During this process, the rubber choke bar is pre-compressed because its natural length is slightly greater than the installation space, thus ensuring a tight, elastic contact between its outer surface and the outer wall of the rudder arm pivot and the inner wall of the rudder blade bearing socket.

[0024] In its natural state, the outer diameter of the rubber choke is slightly larger than the radial width of the annular gap between the outer wall of the rudder arm pivot and the inner wall of the rudder blade bearing socket. During installation, the rubber choke is pre-compressed and placed within this gap, ensuring that it maintains tight elastic contact with both the stationary outer surface of the rudder arm pivot and the rotating inner wall of the rudder blade bearing socket along its entire length, forming an initial seal. Subsequent contact occurs through sliding compression.

[0025] b. Flexible connection

[0026] Using a support shaft and a rotary bearing, and in conjunction with the corresponding mounting cavities on the upper and lower inner walls of the rudder blade bearing socket, a rotatable flexible connection method is used for installation. Similarly, subsequent contact is rolling extrusion contact.

[0027] (II) Working Principle

[0028] The core physical mechanism of the rubber flow-blocking rod device of the present invention in suppressing gap cavitation lies in the fact that it achieves controlled solid filling of the dynamically changing three-dimensional structural gap through a flexible solid seal with specific mechanical properties. Its working principle is based on the continuous interaction between structural motion, material deformation and fluid action, forming a continuous and self-regulating physical process.

[0029] When the ship is sailing straight and the rudder blade is at zero rudder angle, the pre-compressed rubber flow-blocking rod installed in the gap, under the action of its own elastic restoring force, maintains tight initial contact between its circumferential surface and the outer surface of the stationary rudder arm pivot and the inner wall of the rotating rudder blade bearing socket. At this time, the original annular gap is occupied by the solid rubber material, forming a continuous mechanical seal interface. Due to the flexibility and surface adhesion of rubber, this interface can effectively compensate for manufacturing and assembly tolerances, ensuring that the gap channel is substantially blocked under static or low flow velocity conditions.

[0030] When the servo motor drives the rudder blade to rotate around the vertical rudder pin axis, for example, during a right turn, the rubber baffle fixed to the inner wall of the rudder blade bearing moves synchronously. At this time, the movement of the rubber baffle exhibits complex characteristics: in a fixed installation, both ends of the rubber baffle move in a circular motion with the rudder blade, while the area in the middle section that contacts the stationary rudder arm pivot inevitably experiences relative sliding; in a flexible installation, the rubber baffle makes sliding contact with the rudder blade contact surface and rolling or a combination of rolling and sliding contact with the rudder arm pivot. This relative motion is not simply rigid sliding or rolling, but rather an adaptive sealing process involving sliding and compression deformation, dominated by the unique mechanical behavior of the rubber material.

[0031] The core working principle of this invention lies in the adaptive elastic deformation of the rubber flow-blocking rod in three spatial dimensions, which dynamically seals the continuously changing gap.

[0032] In the circumferential direction, the two ends of the rubber choke move with the rudder blade, while the middle part is constrained by the stationary pivot surface, thereby producing coordinated bending deformation. The curvature of this bending deformation is gradient-distributed along the length of the rod and can adapt in real time to the bending geometry of the clearance channel at different rudder angles, thus ensuring that the rod always fits the bending clearance.

[0033] In the radial direction, the rubber baffle can provide continuous initial contact pressure through pre-compression installation. When the rudder rotation causes local radial width changes in the clearance, the rubber material can maintain a stable contact pressure through instantaneous compression or rebound deformation, effectively preventing seal failure caused by clearance size fluctuations.

[0034] Along the axial direction of the rubber baffle, the three-dimensionally varying gap geometry subjects the baffle to shear stress, inducing corresponding shear deformation. This deformation characteristic allows the rubber baffle to adapt to non-uniform changes in the gap profile along the rudder height, achieving axial sealing and following.

[0035] Based on the synergistic effect of the simultaneous elastic deformation occurring in the circumferential, radial, and axial directions, the rubber flow-blocking rod becomes a sealing body capable of dynamically adapting to changes in gap size. This sealing body does not rely on a rigid structure to resist deformation, but rather continuously conforms to and occupies the moving gap space through the low-stiffness elastic deformation of the material itself. Its sealing capability is achieved without relying on any precise motion tracking mechanism, but entirely guaranteed by the inherent property of the rubber material to adapt to continuous changes in boundary geometry.

[0036] From a fluid dynamics perspective, this real-time, adaptive solid filling has a fundamental impact. Traditional open gaps provide a low-resistance discharge channel for high-speed water flow, where the flow accelerates and undergoes complex vortex shedding, easily causing local pressure to drop below the vaporization pressure. In this device, the presence of the rubber baffle physically eliminates this discharge channel. When high-speed water attempts to pass through this area, it directly impacts the solid surface of the rubber baffle, forcibly altering its flow path and dissipating kinetic energy, preventing the formation of a concentrated, high-speed jet. Therefore, the continuous low-pressure core region necessary for cavitation cannot be formed.

[0037] Meanwhile, the damping properties of the rubber material itself also play a positive role in suppressing flow instability and pressure pulsation. It can absorb some of the fluid fluctuation energy, which helps to further stabilize the flow field near the contact area.

[0038] The surface of the rubber baffle can be further designed with a low coefficient of friction, which ensures that while achieving a tight seal, the drag torque added to the rudder blade rotation shaft by sliding friction is controlled within an extremely low range that is permissible by engineering, and will not have a significant impact on the power requirements and handling responsiveness of the servo motor.

[0039] As the rudder blade moves to a new rudder angle and remains stable, the deformation state of the rubber baffle also reaches a new equilibrium. If the external fluid conditions change, its deformation will adjust accordingly to maintain the effectiveness of the seal. The entire process is driven entirely by the movement of the rudder blade and the interaction between the fluid and the structure, requiring no external sensors, controllers, or actuators, achieving fully passive and adaptive operation.

[0040] In summary, this device, by combining the adaptive large deformation capability of flexible solids with the physical occupation of the flow space, completely dismantles the physical basis of gap cavitation from both the flow field structure and energy transfer path levels, providing a simple yet highly efficient and reliable solution.

[0041] As a preferred embodiment, the specific implementation of this invention can be adjusted according to actual operating conditions. The Shore hardness of the rubber is an important parameter, which can be selected within the range of A50 to A80 to balance sealing pressure and rotational resistance. The depth of the mounting groove and the design of the pressure plate must ensure that the end of the rubber baffle remains stable during rudder blade operation. The pre-compression of the rubber baffle needs to be controlled through precise calculation of its natural dimensions and installation clearance to ensure effective contact sealing across the entire rudder angle range.

[0042] Compared with existing technologies, this invention uses a single, integrally molded flexible rubber flow-blocking rod to form a flow-blocking device, thus completely simplifying the structure. This design eliminates all moving parts that require precision machining and maintenance, significantly reducing manufacturing costs and process complexity, and fundamentally avoiding reliability issues caused by the failure of moving mechanisms.

[0043] This device relies on the elasticity and deformability of the rubber material itself to continuously conform to the dynamically changing gap shape as the rudder blade rotates, achieving continuous solid filling and sealing of the flow channel space. This mechanism can continuously and effectively block the high-speed outflow that leads to cavitation, physically eliminating the conditions for the formation of local low-pressure areas, thereby suppressing cavitation. At the same time, the material properties also help to mitigate flow pressure pulsations, playing a positive role in reducing vibration and noise.

[0044] In engineering applications, this device features a symmetrical arrangement and compact structure, allowing for easy installation into existing steering systems with minimal modifications. Its fully passive operation requires no external control, exhibits strong environmental adaptability, and low maintenance needs. While enhancing the reliability and lifespan of steering equipment, it also effectively supports improvements in overall ship performance.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A rubber flow-damping rod device for suppressing cavitation in the gap of a semi-suspended rudder, installed in the annular gap between the inner wall of the bearing socket of the semi-suspended rudder blade and the outer wall of the pivot of the rudder arm, characterized in that, It includes two vertically arranged rubber flow-blocking rods that are connected at both ends to the inner wall of the rudder blade bearing socket and are symmetrical about the longitudinal section of the rudder blade. The outer surface of the rubber flow-blocking rods is in close contact with the inner wall of the bearing socket and the rudder arm pivot.

2. The rubber flow-damping rod device for suppressing cavitation in the semi-suspended rudder clearance according to claim 1, characterized in that, The Shore hardness of the rubber flow-blocking rod is A50~A80.

3. The rubber flow-blocking rod device for suppressing cavitation in the semi-suspended rudder clearance according to claim 1, characterized in that, The rubber flow-blocking rod has a circular or elliptical cross-section, and its two ends are rotatably connected to the upper and lower inner walls of the rudder blade bearing socket. The upper and lower inner walls of the rudder blade bearing socket are respectively provided with mounting cavities. The rubber flow-blocking rod and the rudder arm pivot are in rolling compression contact.

4. The rubber flow-blocking rod device for suppressing cavitation in the semi-suspended rudder clearance according to claim 3, characterized in that, The rubber flow-blocking rod includes a central connecting shaft and a rubber layer disposed outside the connecting shaft; both ends of the connecting shaft are inserted into corresponding mounting cavities disposed on the upper and lower inner walls of the rudder bearing socket.

5. The rubber baffle rod device for suppressing cavitation in the semi-suspended rudder clearance according to claim 4, characterized in that, The two ends of the connecting shaft are connected to the mounting cavity via rotary bearings.

6. The rubber flow-blocking rod device for suppressing cavitation in the semi-suspended rudder clearance according to claim 1, characterized in that, The rubber flow-blocking rod has a circular or elliptical cross-section, and its two ends are fixedly connected to the upper and lower inner walls of the rudder bearing socket; the rubber flow-blocking rod and the rudder arm pivot are in sliding and compressive contact.

7. The rubber baffle rod device for suppressing cavitation in the semi-suspended rudder clearance according to claim 6, characterized in that, The inner wall of the rudder bearing socket is provided with mounting grooves on the upper and lower sides. The end of the rubber flow deflector is provided with an enlarged anchor head or embedded with a metal core and is fixed in the mounting groove by a high-strength adhesive and a mechanical pressure plate.

Images