Vibration isolation system for marine propulsion gearbox and structural design method

Abstract

The invention discloses a vibration isolation system for a marine propulsion gearbox and a structural design method, and belongs to the technical field of ship structural design. The invention aims to solve the problem that a clear vibration isolation system and a structure design method for the marine propulsion gearbox device do not exist at present. The vibration isolator structure and the arrangement mode of the vibration isolation system suitable for the marine propulsion gearbox are designed by considering the using working conditions of rolling and pitching under the marine condition and considering the overturning moment load of the gearbox at the same time, and according to the marine condition, the vibration isolator structure and the arrangement mode of the vibration isolation system suitable for the marine propulsion gearbox are designed. The overturning moment of a gearbox is obtained through calculation of the power, the rotating speed and the gravity of the unit under the rated operation condition, meanwhile, the displacement of each interface of the unit is obtained through calculation, and the unit displacement of the position of a vibration isolator is inversely calculated, so that the needed limiting value is determined; and determining design parameters of the limiting gap of the vibration isolator according to the calculated limiting value so as to obtain the specific size of the limiting bolt meeting the bearing strength, and obtaining the specific size of the conical limiting steel part according to the limiting gap.

Description

Technical Field

[0001] The invention belongs to the technical field of ship structure design, and in particular relates to a vibration isolation system and a structural design method for a ship propulsion gear box. Background Art

[0002] The structural noise of the main engine equipment of ships not only affects the comfort of sailing, but more importantly, it affects the combat performance of military ships. The excitation frequency of the gearbox is mostly low-frequency. Compared with high-frequency, ships are more likely to radiate low-frequency noise through the hull, so that the enemy can discover the ship through sonar, expose the target, and destroy the concealment. In addition, with the development of science and technology, the structural design of marine propulsion gearbox devices is becoming lighter and lighter, but the power of the equipment has increased significantly, resulting in a continuous increase in the overturning torque of the gearbox. At the same time, considering the operating conditions of the ship's roll and pitch, the design difficulty of the equipment's vibration isolation system is increasing, and the structure is becoming more and more complex.

[0003] Due to the complex boundary conditions that need to be considered, the vibration isolation system design usually includes multiple types of limit devices such as lateral, axial and vertical, which makes the vibration isolation system design of the unit complicated and increases the design and processing costs. In addition, there is currently no clear vibration isolation system and structural design method for marine propulsion gearbox devices for designers to refer to. Summary of the invention

[0004] The invention aims to solve the problem that there is no clear vibration isolation system and structural design method for a marine propulsion gearbox device at present.

[0005] A vibration isolation system for a marine propulsion gearbox, the vibration isolation system comprising a plurality of identical vibration isolators, the vibration isolators comprising: an upper steel piece, a lower steel piece, a stop bolt, a conical stop steel piece and a conical rubber ring;

[0006] A conical rubber ring is provided between the lower steel part and the upper steel part for vibration isolation;

[0007] The lower steel part is rigidly connected to the conical limiting steel part, and the conical limiting steel part is a steel part; the limiting bolt is rigidly fixedly connected to the upper steel part, and cooperates with the conical limiting steel part for limiting;

[0008] There is a gap between the bottom surface of the limit bolt and the upper surface of the lower steel part, which is the vertical limit gap; there is a gap between the side surface of the limit bolt and the inner wall of the conical limit steel part, which is the lateral limit gap.

[0009] Furthermore, the limiting bolt is a bolt-shaped limiting structure.

[0010] Furthermore, a radial interface of the main body portion of the limiting bolt is elliptical.

[0011] Furthermore, the conical limiting steel piece is a hollow structure, and the limiting bolt cooperates with the conical limiting steel piece in that the limiting bolt penetrates into the hollow structure from one side of the upper steel piece to achieve the cooperation and limiting.

[0012] A design method for a vibration isolation system structure for a marine propulsion gearbox, comprising:

[0013] Firstly, the excitation frequency of the marine propulsion main engine and gearbox under various working conditions is determined, and the vertical natural frequency f of the vibration isolation system is determined based on the excitation frequency; at the same time, the support stiffness K of the vibration isolation system is calculated according to the overall mass m above the vibration isolation system; the selection of the vertical natural frequency is limited based on the support stiffness K;

[0014] Design the integral support raft for the propulsion main engine and gearbox. The vibration isolation system includes multiple vibration isolators. Arrange the vibration isolators and determine the number of vibration isolators according to the installation bottom surface and space of the raft.

[0015] Based on the number of vibration isolators arranged in the vibration isolation system and the support stiffness of the vibration isolation system, the stiffness value and load of a single vibration isolator are calculated; based on the stiffness of a single vibration isolator, the minimum allowable size of the vibration isolator is determined, and combined with the design conditions of the unit installation surface, the overall size and interface size of the vibration isolator are determined;

[0016] So far, the layout position, quantity, size, stiffness and load of the vibration isolation system have been determined, and a finite element model including the propulsion main engine, gearbox, raft base and vibration isolation system has been established;

[0017] According to the marine conditions, the power, speed and self-gravity under the rated operating conditions of the unit are used to calculate the overturning moment of the gearbox, and at the same time, the displacement of each interface of the unit is calculated; the displacement compensation amount of each interface position is determined according to the design, and the calculated value of the interface displacement under the marine conditions and the gearbox overturning moment operating conditions is compared. If the actual displacement compensation amount of the interface is greater than the calculated value, it means that the current operating conditions have no limit and cannot meet the normal operating conditions of the unit, and there is a possibility that the interface displacement is too large to cause the unit failure, then the vibration isolator structure in the vibration isolation system for a marine propulsion gearbox is used to design the vibration isolator;

[0018] Based on the rigid linear system, the displacement of the unit at the isolator position is back-calculated according to the actual interface compensation, so as to determine the required limit value; the design parameters of the limit gap of the isolator are determined according to the calculated limit value; the specific size of the limit bolt that meets the bearing strength is obtained according to the isolator structure and design parameters; the specific size of the conical limit steel part is obtained according to the limit gap.

[0019] Furthermore, the vertical natural frequency f of the vibration isolation system is selected and determined based on the excitation frequency and outside the frequency avoidance rate range.

[0020] Furthermore, the frequency avoidance rate is selected to be 20%.

[0021] Furthermore, the calculation formula of the support stiffness of the floating raft vibration isolation system is K = m·(2πf) 2 .

[0022] Furthermore, in the process of arranging the vibration isolators according to the installation bottom surface and space of the raft and determining the number of the vibration isolators, the vibration isolators are arranged to ensure that the stiffness center and the center of gravity coincide with each other as much as possible; if the coincidence condition is not met, the coincidence deviation shall not exceed 10%.

[0023] Furthermore, according to the marine conditions, when the overturning moment of the gearbox is calculated based on the power, speed and self-gravity of the unit under rated operating conditions, the propulsion equipment corresponding to the propulsion main engine is required to meet the operating conditions of rolling 45° and pitching 10°.

[0024] Beneficial effects:

[0025] At present, the power and overturning moment of ship propulsion main engines and gearboxes are large, and the rolling and pitching operating conditions during ship navigation need to be considered at the same time. The displacement of each interface is easy to exceed the compensation capacity, and the vibration isolation system needs to be designed with three-way limit, which leads to the need to design multiple types of vibration isolators and limiters for the vibration isolation system. In response to this problem, the present invention provides a feasible design method for a vibration isolation system and structure for a ship propulsion gearbox. In the structural design method, the present invention provides a vibration isolator design structure with three-way limit capability at the same time, and various key design parameters of the vibration isolator can be obtained through the design method provided by the present invention. The structural design method uses only one vibration isolator to realize the limit function that can only be achieved by combining multiple vibration isolators and limiters. Therefore, the design difficulty and design cost are greatly reduced, the lateral space size of the propulsion gearbox is reduced, and the power density is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A flow chart of the design method of the vibration isolation system structure for a marine propulsion gearbox;

[0027] Figure 2 is a schematic diagram of the vibration isolator structure;

[0028] Figure 3 It is a schematic diagram of the bottom structure of the floating raft support;

[0029] Figure 4 This is a schematic diagram of the vibration isolator arrangement;

[0030] Figure 5 It is a three-dimensional model diagram of the unit including the vibration isolation system parameters;

[0031] Figure 6 Design a front view of the vibration isolator structure;

[0032] Figure 7 Design a top view of the vibration isolator structure;

[0033] Figure 8 Design an isometric drawing for the vibration isolator structure. DETAILED DESCRIPTION

[0034] In view of the problems existing in the background technology, the present invention proposes a vibration isolation structure design, which can simultaneously meet the three-way limiting capabilities of lateral, vertical and axial directions. The structure can greatly simplify the complexity of the design and can also reduce the overall design and processing cost of the vibration isolation system. At the same time, the vibration isolation design method of the marine propulsion gearbox device proposed in the present invention provides a calculation method and a selection method for the design parameters of the vibration isolation system, which can be used for guidance in the design stage and has certain application value. The following is an explanation in conjunction with a specific implementation method.

[0035] Specific implementation method 1: Combination Figure 1 To explain this embodiment,

[0036] The present embodiment provides a method for designing a vibration isolation system structure for a marine propulsion gearbox, comprising the following steps:

[0037] First, it is necessary to determine the excitation frequency of the marine propulsion main engine and gearbox under various working conditions, such as the rotor rotation frequency, harmonic frequency, blade frequency of the main engine equipment such as the motor, internal combustion engine or steam turbine, and the rotation frequency and meshing frequency of all rotors in the gearbox.

[0038] According to the above frequency, select the appropriate vertical natural frequency f (Hz) of the vibration isolation system outside the avoidance rate range. In this embodiment, the frequency avoidance rate is 20%; at the same time, according to the overall mass m (kg) above the floating raft vibration isolation system, the support stiffness K (N / m) of the floating raft vibration isolation system can be calculated. The calculation formula of the support stiffness of the system is K = m·(2πf) 2 The stiffness cannot be too soft, otherwise the displacement of the unit will be too large; if the stiffness is too large, the vibration isolation effect will be poor; therefore, the vertical natural frequency can be selected as low as possible while satisfying the displacement conditions of the unit.

[0039] Design an integral supporting raft for the propulsion main engine and gearbox, arrange the vibration isolators and determine the number of them according to the installation bottom surface and space of the raft, and arrange the vibration isolators to ensure that the stiffness center and the center of gravity coincide as much as possible; if there are objective conditions for non-coincidence, the coincidence deviation shall not exceed 10%. The coincidence deviation refers to the ratio of the distance between the stiffness center and the center of gravity to the farthest distance of the vibration isolator. The farthest distance of the vibration isolator refers to the farthest distance between the vibration isolators in a certain direction.

[0040] Based on this, the number of vibration isolators in the vibration isolation system is obtained, and the stiffness and load of a single vibration isolator can be calculated based on the total stiffness of the system. The number of vibration isolators should not be too large, which will affect the layout space and installation; the number of vibration isolators should not be too small, which will result in excessive stiffness of a single vibration isolator and reduce the safety of the vibration isolation system.

[0041] The minimum allowable size of the isolator can be determined based on the stiffness of a single isolator. Combined with the design conditions of the unit installation surface, the appropriate overall dimensions and interface dimensions of the isolator can be determined.

[0042] At this point, the layout, quantity, size, stiffness and load of the vibration isolation system have been determined, and a finite element model including the propulsion main engine, gearbox, raft base and vibration isolation system can be established.

[0043] According to marine conditions, the propulsion equipment must meet the operating conditions of 45° roll and 10° pitch. At the same time, the overturning moment of the gearbox can be calculated based on the power, speed and self-gravity under the rated operating conditions of the unit. Considering the above operating conditions, the displacement of each interface of the unit under this condition can be calculated, such as the coupling and the oil and water pipeline equipment interface.

[0044] Determine the displacement compensation amount of each interface position according to the design, and compare the calculated interface displacement value under the marine conditions and the gearbox overturning moment operating conditions; if the actual displacement compensation amount of the interface is greater than the calculated value, it means that the current operating conditions have no limit and cannot meet the normal operating conditions of the unit, and there is a possibility that the interface displacement is too large to cause the unit failure. In this case, the vibration isolator limit design structure proposed in the present invention can be adopted, such as Figure 2 shown.

[0045] The upper and lower parts of the vibration isolator are steel structures, namely the upper steel part 1 and the lower steel part 5, which are used to ensure the structural strength; between the lower steel part and the upper steel part of the vibration isolator is a conical rubber ring 3 structure for vibration isolation.

[0046] The lower steel part 5 is rigidly connected to the conical limiting steel part 4. The conical limiting steel part 4 is a steel part with a hollow structure. The hollow structure has a limiting structure in the shape of a bolt (without thread) inserted from the upper steel part, namely, the limiting bolt 2.

[0047] The stop bolt 2 can be elliptical (the radial interface of the main body is elliptical) to simultaneously meet the design requirements of different axial and lateral limit clearances of the unit. The stop bolt 2 is rigidly fixedly connected to the upper steel member 1.

[0048] There is a gap between the bottom surface of the limit bolt 2 and the upper surface of the lower steel member 5, which is a vertical limit gap; there is a gap between the side surface of the limit bolt 2 and the inner wall of the conical limit steel member 4, which is a lateral limit gap.

[0049] Considering the marine propulsion main engine and gearbox as a rigid linear system, the displacement of the unit at the isolator position can be back-calculated based on the actual interface compensation, thereby determining the required limit value. The design parameters of the isolator limit clearance can be determined based on the limit value calculated above.

[0050] According to the above design structure, the specific size of the limit bolt 2 that meets the bearing strength can be calculated. According to the limit gap, the specific size of the conical limit steel piece 4 can be obtained.

[0051] At this point, all key design parameters for the vibration isolation system design for marine propulsion gearboxes have been determined and the design is complete.

[0052] Example

[0053] For a set of marine propulsion main engine and gearbox device, the design method of the present invention is used to design a vibration isolation system, which specifically includes the following steps:

[0054] 1. Determine all excitation frequencies of the marine propulsion main engine and gearbox: The excitation within the low-frequency range of the unit is the rotor rotation frequency, with speeds of 1000r / min and 200r / min, respectively, and the corresponding excitation frequencies are 16.7Hz and 3.3Hz.

[0055] 2. Avoid each excitation frequency and select the natural frequency of the equipment vibration isolation system: In order to maximize the avoidance rate, the natural frequency is selected as 10Hz. This frequency can ensure the vibration isolation effect to a certain extent, and at the same time ensure that the unit system stiffness is large enough.

[0056] 3. Calculate the support stiffness of the vibration isolation system based on the mass of the equipment: The mass of the unit is 30t, and the support stiffness of the vibration isolation system can be calculated to be 1.3E8N / m.

[0057] 4. Determine the bottom installation conditions of the propulsion main engine and gearbox integral floating raft support: According to the unit layout, the design of the integral floating raft structure is completed. Figure 3 As shown. The section line part is designed as the area where the vibration isolator can be installed.

[0058] 5. Arrange vibration isolators and determine the quantity, load, overall dimensions and interface dimensions: According to the bottom surface, the number of suitable vibration isolators is 10, and the layout positions are as follows: Figure 4 As shown in the figure, the vibration isolation system layout ensures that the stiffness center coincides with the center of gravity of the unit. The overall dimensions are 300mm*300mm, and the interface is 260mm*260mm.

[0059] 6. Determine the stiffness and load of a single vibration isolator based on the overall support stiffness and mass of the system: the total stiffness of the system is 1.3E8N / m, there are 10 vibration isolators, and the stiffness of a single vibration isolator is 1.3E7N / m. The total mass of the system is 30t, and the load of a single vibration isolator is 3t.

[0060] 7. Establish a finite element model of the main engine group including the vibration isolation system, such as Figure 5 shown.

[0061] 8. Calculate the displacement of each interface of the unit under the ship's roll and pitch operating conditions and the gearbox overturning moment: After finite element modeling and calculation, the displacement calculation results of each interface under the current vibration isolation system design scheme can be obtained as shown in the following table.

[0062] Table 1 Interface displacement

[0063]

[0064]

[0065] 9. Compare the calculated value with the actual allowable displacement compensation value to find out the position with the largest displacement compensation difference among all interfaces: the calculated lateral displacement of interface 5 is 4.51mm, and the maximum radial displacement compensation of the interface at this position cannot exceed 2.8mm, which cannot meet the compensation conditions of the interface at this position.

[0066] 10. Consider the equipment as a linear system, and reverse the required limit clearance of the vibration isolator according to the allowable compensation of the interface displacement: According to the actual displacement compensation conditions of interface 5, it can be reversed to obtain a lateral limit displacement of 1.2mm, an axial limit displacement of 2.3mm, and a vertical limit displacement of 0.9mm. The vertical limit clearance needs to take into account the deformation of the vibration isolator after bearing, and the static deformation under the vertical load is 4.5mm. At the same time, considering the creep of rubber, the vertical clearance can be calculated to be 5.4mm. Therefore, the limit clearances of the vibration isolator in the horizontal, axial, and vertical directions are 1.2mm, 2.3mm, and 5.4mm, respectively.

[0067] 11. The key design parameters of the vibration isolation system are known.

[0068] 12. Determine the vibration isolator structure that meets the strength requirements based on the design parameters: Design the structure as follows: Figure 6-Figure 8 As shown, Figure 6 This is the front view of the vibration isolator structure design. Figure 7 Design the top view of the vibration isolator structure. Figure 8 Design an isometric drawing for the vibration isolator structure.

[0069] 13. Determine that parameters such as external dimensions can meet strength requirements.

[0070] 14. Complete the design of vibration isolation system for marine propulsion gearbox.

[0071] The above calculation examples of the present invention are only used to explain the calculation model and calculation process of the present invention in detail, and are not intended to limit the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A vibration isolation system for a marine propulsion gearbox, characterized in that: The vibration isolation system comprises a plurality of identical vibration isolators, wherein the vibration isolators comprise: an upper steel member (1), a lower steel member (5), a stop bolt (2), a conical stop steel member (4) and a conical rubber ring (3); A conical rubber ring (3) is arranged between the lower steel part and the upper steel part for vibration isolation; The lower steel part (5) is rigidly connected to the conical limiting steel part (4), and the conical limiting steel part (4) is a steel part; the limiting bolt (2) is rigidly fixedly connected to the upper steel part (1), and cooperates with the conical limiting steel part (4) for limiting; A gap is left between the bottom surface of the limit bolt (2) and the upper surface of the lower steel member (5), and the gap is a vertical limit gap; a gap is left between the side surface of the limit bolt (2) and the inner wall of the conical limit steel member (4), and the gap is a horizontal limit gap.

2. A vibration isolation system for a marine propulsion gearbox according to claim 1, characterized in that: The limiting bolt (2) is a bolt-shaped limiting structure.

3. A vibration isolation system for a marine propulsion gearbox according to claim 2, characterized in that: The radial interface of the main body part of the limiting bolt (2) is elliptical.

4. A vibration isolation system for a marine propulsion gearbox according to any one of claims 1 to 3, characterized in that: The conical limiting steel piece (4) is a hollow structure, and the limiting bolt (2) cooperates with the conical limiting steel piece (4) in that the limiting bolt penetrates into the hollow structure from one side of the upper steel piece to achieve matching limiting.

5. A design method for a vibration isolation system structure for a marine propulsion gearbox, characterized in that: include: First, determine the excitation frequency of the marine propulsion main engine and gearbox under various working conditions, and based on the excitation frequency, determine the vertical natural frequency f of the vibration isolation system; At the same time, according to the overall mass m above the vibration isolation system, the support stiffness K of the vibration isolation system is calculated; Selection of vertical natural frequency limited by support stiffness K; Design the integral support raft for the propulsion main engine and gearbox. The vibration isolation system includes multiple vibration isolators. Arrange the vibration isolators and determine the number of vibration isolators according to the installation bottom surface and space of the raft. Based on the number of vibration isolators arranged in the vibration isolation system and the support stiffness of the vibration isolation system, the stiffness value and load of a single vibration isolator are calculated; based on the stiffness of a single vibration isolator, the minimum allowable size of the vibration isolator is determined, and combined with the design conditions of the unit installation surface, the overall size and interface size of the vibration isolator are determined; So far, the layout position, quantity, size, stiffness and load of the vibration isolation system have been determined, and a finite element model including the propulsion main engine, gearbox, raft base and vibration isolation system has been established; According to the marine conditions, the power, speed and self-gravity of the unit under rated operating conditions are used to calculate the overturning moment of the gearbox, and at the same time, the displacement of each interface of the unit is calculated; the displacement compensation amount of each interface position is determined according to the design, and the calculated value of the interface displacement under the marine conditions and the gearbox overturning moment operating conditions is compared. If the actual displacement compensation amount of the interface is greater than the calculated value, it means that the current operating conditions are not able to meet the normal operating conditions of the unit, and there is a possibility that the unit failure may be caused by excessive interface displacement. The vibration isolator structure in the vibration isolation system for a marine propulsion gearbox as described in any one of claims 1 to 4 is used to design the vibration isolator; Based on a rigid linear system, the displacement of the unit at the position of the vibration isolator is calculated according to the actual interface compensation amount, thereby determining the required limit value; the design parameters of the limit gap of the vibration isolator are determined according to the calculated limit value; the specific size of the limit bolt (2) that meets the bearing strength is obtained according to the vibration isolator structure and design parameters; and the specific size of the conical limit steel part (4) is obtained according to the limit gap.

6. The design method of a vibration isolation system structure for a marine propulsion gearbox according to claim 5, characterized in that: The vertical natural frequency f of the vibration isolation system is determined based on the excitation frequency and is selected outside the frequency avoidance rate range.

7. The design method of a vibration isolation system structure for a marine propulsion gearbox according to claim 5, characterized in that: The frequency avoidance rate is selected as 20%.

8. The design method of a vibration isolation system structure for a marine propulsion gearbox according to claim 5, characterized in that: The calculation formula of the support stiffness of the floating raft vibration isolation system is K = m (2πf) 2 .

9. The design method of a vibration isolation system structure for a marine propulsion gearbox according to claim 5, characterized in that: In the process of arranging the vibration isolators according to the bottom surface and space of the raft installation and determining the number of vibration isolators, the vibration isolators are arranged as far as possible to ensure that the stiffness center and the center of gravity coincide with each other; if the coincidence condition is not met, the coincidence deviation shall not exceed 10%.

10. The design method of a vibration isolation system structure for a marine propulsion gearbox according to claim 5, characterized in that: According to the marine conditions, when the overturning moment of the gearbox is calculated based on the power, speed and self-gravity of the unit under rated operating conditions, the propulsion equipment corresponding to the propulsion main engine is required to meet the operating conditions of rolling 45° and pitching 10°.

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