Marine electric machine with eccentric end cover

Abstract

A marine motor with eccentric end cover, comprising a frame, an end cover connected to the frame, a stator connected to the end cover in the frame, a bearing connected to the end cover, a rotating shaft connected to the bearing through a bearing bush, and a rotor corresponding to the stator and arranged on the rotating shaft; the axial center of the end cover is offset relative to the axial center of the rotating shaft, and the fit clearance between the bearing bush and the rotating shaft and between the stator and the rotor is adjusted by adjusting the offset degree of the end cover relative to the rotating shaft. The invention solves the problems of uneven distribution of bearing clearance and stator-rotor air gap caused by the self-weight sag of the rotating shaft in the traditional concentric end cover type marine motor, complicated assembly and debugging, and difficult on-site clearance correction.

Description

Technical Field

[0001] This invention belongs to the field of motor manufacturing, and in particular relates to a marine motor with an eccentric end cap. Background Technology

[0002] Marine synchronous motors are core equipment in ship electrical and propulsion systems, widely used as main generators, emergency generators, and high-power propulsion motors in various ships and marine engineering equipment. Their reliability directly affects ship navigation safety and operational efficiency. The long-term continuous operation of ship engine rooms, coupled with intense vibration and shock, and the humid and salt-spray environment, places far higher demands on the motor's assembly precision, operational stability, and ease of maintenance compared to land-based motors.

[0003] The end cover is positioned and connected to the base via a stop, and integrates the bearing assembly and exciter stator on its inner side. Its assembly accuracy directly determines the shaft's rotation accuracy and the uniformity of the air gap between the stator and rotor. Currently, conventional marine motors generally adopt a concentric end cover structure, meaning that the reference center of the end cover stop is completely coaxial with the center of the inner bearing and stator mounting surfaces. After assembly, the radial distribution of the bearing clearance and the exciter air gap is completely fixed, with no adjustment margin.

[0004] In practical applications, this structure cannot compensate for the sag deviation caused by the shaft's own weight. Large and medium-sized marine motor shafts have large spans and high weights, resulting in sag deflection under gravity. This leads to uneven bearing clearance and excitation air gap, concentrated load on the lower bearing bush, susceptibility to uneven wear, and poor oil film stability. Simultaneously, uneven air gap causes unilateral magnetic pull, exacerbating unit vibration and increasing the risk of failure. Furthermore, the machining and assembly tolerance is low; clearance accuracy depends entirely on the coaxiality of parts machining and assembly. Accumulated tolerances easily lead to deviations exceeding limits, requiring upgraded parts machining grades. After deviations occur, manual repair and rework are necessary, resulting in high manufacturing costs and low assembly efficiency. Moreover, on-site maintenance is difficult. Limited space in ship engine rooms and a lack of precision machining equipment mean that worn bearing bushes and deteriorated clearances cannot be calibrated on-site, requiring factory disassembly and repair, leading to long downtime and impacting ship operational efficiency. Finally, it is impossible to dynamically correct operational degradation. Long-term operation will cause wear of bearings and thermal deformation of the structure to continuously deteriorate the clearance accuracy. The concentric end caps cannot be compensated by adjustment and can only be replaced with spare parts. The maintenance cost throughout the entire life cycle is high, making it difficult to meet the high reliability requirements of ocean-going vessels that sail without interruption. Summary of the Invention

[0005] The purpose of this invention is to provide a marine motor with an eccentric end cover, so as to solve the technical problems of existing marine motors with concentric end covers that cannot compensate for the sag of the shaft due to its own weight, resulting in uneven distribution of bearing clearance and stator-rotor air gap, complicated assembly and calibration, and high difficulty in on-site operation and maintenance.

[0006] To achieve the above objectives, the specific technical solution of the present invention for a marine motor employing an eccentric end cap is as follows:

[0007] A marine motor with an eccentric end cover includes a frame, an end cover connected to the frame, a stator connected to the end cover inside the frame, a bearing connected to the end cover, a rotating shaft connected to the bearing via a bearing bush, and a rotor disposed on the rotating shaft corresponding to the stator.

[0008] The axial center of the end cover is offset relative to the axial center of the rotating shaft. By adjusting the degree of offset of the end cover relative to the rotating shaft, the fitting clearance between the bearing bush and the rotating shaft, as well as between the stator and the rotor, is adjusted.

[0009] As a further improvement of the present invention, the bearing includes a bearing housing and a bearing bush, the bearing housing is fixedly connected to the end cover, and the bearing bush is embedded and fixed in the inner hole of the bearing housing; an annular fitting clearance is formed between the inner wall of the bearing bush and the outer wall of the journal of the rotating shaft, and the dimensional deviation of the upper and lower sides of the annular clearance is corrected by the vertical displacement of the end cover.

[0010] As a further improvement of the present invention, the stator is fixedly installed on the end face of the end cover facing the machine base, and the radial displacement is generated synchronously with the vertical height adjustment of the end cover, thereby synchronously adjusting the uniformity of the vertical distribution of the gap between the stator and the rotor.

[0011] As a further improvement of the present invention, the base opening is provided with a plurality of connecting holes in the circumferential direction, and the end cover is provided with a vertical slot corresponding to the connecting holes. The bolt passes through the vertical slot and enters the connecting hole to connect the end cover and the base, and the vertical height of the end cover is adjusted by the vertical slot.

[0012] As a further improvement of the present invention, the base and the end cover are connected by a stop structure, the stop structure including a concave stop at the opening of the base and a convex stop on the end cover; the cylindrical surfaces on both sides of the convex stop are clearance-fitted with the corresponding inner surfaces of the concave stop, and a vertical adjustment gap is reserved between the upper and lower sides of the convex stop and the concave stop to provide displacement space for the vertical height adjustment of the end cover.

[0013] As a further improvement of the present invention, the stator is an exciter stator and the rotor is an exciter rotor. The exciter stator moves vertically in sync with the end cover to calibrate the vertical distribution of the excitation air gap, counteract the off-center load of the excitation magnetic field caused by the sag of the shaft itself, and ensure the stability of the excitation output.

[0014] As a further improvement of the present invention, the axial offset of the end cap relative to the rotating shaft is in the range of 0.5-1mm.

[0015] As a further improvement of the present invention, the base and the end cover are connected by a stop structure, the stop structure including a concave stop at the opening of the base and a convex stop on the end cover; a uniform radial gap is reserved between the concave stop and the convex stop; wedge adjustment structures are respectively embedded at the upper and lower ends of the end cover, the wedge adjustment structure including an outer wedge and an inner wedge that fit together by inclined surfaces, the outer wedge drives the inner wedge to abut against the base along the inclined surface under the action of an axial bolt, thereby adjusting the radial gap between the base and the end cover.

[0016] Beneficial effects:

[0017] The weight of the shaft of large and medium-sized marine motors easily causes sagging deformation, resulting in uneven distribution of the oil gaps and air gaps between the stator and rotor. This invention integrates the end cover, stator, bearing, and bearing bush into a single stationary assembly. When the offset of the end cover relative to the shaft is changed, the stator and bearing bush simultaneously undergo radial displacement, correcting the vertical dimensional deviations of the two gaps at once. This avoids concentrated load and localized uneven wear on the lower bearing bush, while also eliminating unilateral magnetic pull caused by uneven air gaps. This reduces the probability of unit vibration, rotor rubbing, and bearing burnout, significantly improving the long-term operational stability of the motor.

[0018] Traditional concentric end-cover motors require separate calibration of bearing clearance and stator-rotor air gap, leading to repeated disassembly and repair of parts. This invention, however, calibrates both clearances simultaneously by adjusting the end-cover offset, eliminating the need for separate disassembly and repair of the stator or bearing components. This offsets cumulative coaxiality errors caused by parts machining and assembly, reduces the precision requirements for component machining, minimizes assembly rework, improves the first-pass yield of the entire machine, and shortens the production and debugging cycle.

[0019] This invention repairs gaps simply by adjusting the end cover offset, eliminating the need for complete disassembly and return to the factory. When motor bearings wear and gap deterioration occur after long-term operation, dimensional deviations can be compensated by readjusting the end cover offset, eliminating the need for frequent replacement of expensive spare parts such as bearings and end covers. This reduces ship downtime for maintenance and lowers ship maintenance and spare parts inventory costs. The stator and bearings are uniformly fixed on the end cover to form a static unit. During adjustment, the relative positions of the stator and bearings remain unchanged, ensuring synchronous and highly matched gap adjustments. Fine-tuning is achieved through the overall offset of the end cover, eliminating the need to disassemble internal components. The overall structure is highly rigid, capable of withstanding continuous vibration and impact during ship navigation, and is less prone to secondary gap offsets over long-term use, making it suitable for the demanding conditions of high vibration and continuous operation in marine applications. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a marine motor structure using an eccentric end cap according to the present invention;

[0021] Figure 2 This is a schematic diagram of end cap adjustment;

[0022] The markings in the diagram are as follows: 1. Base; 2. End cover; 21. End cover axis; 3. Stator; 4. Rotor; 5. Shaft; 51. Shaft axis; 52. Journal; 53. Journal outer wall; 6. Bearing; 61. Bearing bush; 62. Bearing housing; 63. Bushing inner wall. Detailed Implementation

[0023] To better understand the purpose, structure, and function of this invention, the following detailed description of a marine motor with an eccentric end cap, in conjunction with the accompanying drawings, is provided.

[0024] Example 1:

[0025] like Figure 1 The marine motor shown includes a frame 1, an end cover 2, a stator 3, a rotor 4, a shaft 5, and a bearing 6. By offsetting the axis of the end cover 2 relative to the axis of the shaft 5, the bearing clearance and the air gap between the stator and rotor are adjusted synchronously to compensate for the uneven clearance caused by the shaft's own weight sagging.

[0026] The base 1 is the main supporting housing of the motor, with an opening at the end for installing the end cover 2; the interior of the base 1 forms a closed cavity that accommodates the stator, rotor and shaft, and undertakes the load-bearing and protection functions of the whole machine.

[0027] The rotating shaft 5 passes through the machine base 1 and is the rotating output component of the motor. The rotor 4 is fixedly installed on the rotating shaft 5 at the position corresponding to the stator 3, and the rotor 4 rotates synchronously with the rotating shaft 5. The journal 52 of the rotating shaft 5 cooperates with the bearing bush 61 to form a rotating support pair, and the theoretical rotation center of the rotating shaft 5 is the shaft axis 51.

[0028] The bearing 6 includes a bearing housing 62 and a bearing bush 61. The bearing housing 62 is fixedly connected to the outer side of the end cover 2, providing a mounting base for the bearing bush 61. The bearing bush 61 is embedded and fixed in the inner hole of the bearing housing 62. An annular bearing fit clearance is formed between the inner wall 63 of the bush and the outer wall 53 of the journal, providing radial support for the rotating shaft 5. At the same time, the lubricating oil in the clearance forms a bearing oil film to achieve low friction rotation.

[0029] The stator 3 is fixedly installed on the end face of the end cover 2 facing the inside of the base 1, and is arranged radially corresponding to the rotor 4. The stator and rotor air gap is formed between them, which is the core magnetic field gap for motor energy conversion.

[0030] End cover 2 is an integrated support component at the end of the motor. The stator 3 and bearing 6 are rigidly connected to the inner side of end cover 2 and move synchronously with it. The theoretical center of rotation of end cover 2 is its axis 21. In the assembled state, the axis 21 of end cover is offset vertically relative to the axis 51 of the rotating shaft. By adjusting the degree of offset of end cover 2 relative to the rotating shaft 5, the bearing clearance between the bearing bush 61 and the rotating shaft 5, as well as the air gap size distribution between the stator 3 and the rotor 4, can be adjusted synchronously. Figure 2 As shown, L1 and L2 are the gaps between the outer wall 53 of the journal and the inner wall 63 of the bearing at the upper and lower ends, respectively, and L3 is the offset distance between the end cover axis 21 and the shaft axis 51. The vertical offset range of the end cover axis 21 relative to the shaft axis 51 is 0.5-1mm, which can be adapted to the conventional deflection range of the shaft of large and medium-sized marine motors under its own weight.

[0031] In this embodiment, the stator 3 is the exciter stator, and the rotor 4 is the exciter rotor. Together, they constitute the excitation supply unit of the marine synchronous motor. The exciter stator moves vertically synchronously with the end cover 2, which can calibrate the vertical distribution of the excitation air gap, counteract the off-center load of the excitation magnetic field caused by the sag of the shaft 5 due to its own weight, and ensure the stability of the excitation output.

[0032] The base 1 has several evenly spaced connecting holes around its open end. The flange of the end cover 2 has vertical slots corresponding to these connecting holes. Connecting bolts pass through these vertical slots and are screwed into the connecting holes of the base 1, thus securing the end cover 2 to the base 1. The vertical slots extend vertically, providing vertical displacement adjustment space for the end cover 2. After loosening the connecting bolts, the end cover 2 can be adjusted vertically to change its installation height.

[0033] The base 1 and end cover 2 are radially guided and positioned by a stop structure, which includes a concave stop at the opening of the base 1 and a convex stop on the outer edge of the end cover 2. The cylindrical surfaces on both sides of the convex stop and the corresponding inner surfaces of the concave stop are precisely clearance-fitted, forming a horizontal guide and limiting structure that restricts the horizontal displacement of the end cover 2, ensuring that it moves only vertically during adjustment. A vertical adjustment gap is reserved between the upper and lower outer surfaces of the convex stop and the upper and lower inner walls of the concave stop. This gap is larger than the maximum adjustment stroke of the end cover 2, providing sufficient displacement space for the vertical height adjustment of the end cover 2.

[0034] When it is detected that the bearing clearance and stator-rotor air gap are uneven due to the shaft 5 sagging under its own weight, loosen all connecting bolts and adjust the installation height of the end cover 2 vertically upwards. The end cover 2 drives the bearing seat 62, bearing bush 61 and stator 3 to move upwards synchronously, so that the lower dimension of the bearing clearance increases and the upper dimension decreases, and the vertical distribution of the stator-rotor air gap becomes more uniform. After adjusting to the target position, tighten all connecting bolts to complete the clearance calibration.

[0035] Example 2:

[0036] The only difference between this embodiment and Embodiment 1 is the adjustment connection structure between the end cover 2 and the base 1. The structure, connection relationship and function of the rest of the base 1, stator 3, rotor 4, shaft 5 and bearing 6 are the same as in Embodiment 1.

[0037] In this embodiment, the base 1 and the end cover 2 are connected by a stop structure, which includes a concave stop at the opening of the base 1 and a convex stop on the outer edge of the end cover 2. A uniform radial gap is reserved between the upper and lower ends of the inner wall of the concave stop and the outer wall of the convex stop to provide displacement space for the radial adjustment of the end cover 2. Positioning pin structures are provided on the left and right sides of the stop to restrict the horizontal displacement of the end cover 2 and ensure that the end cover 2 moves only in the vertical direction during the adjustment process.

[0038] At symmetrical positions above and below the stop circumference, a set of wedge adjustment structures is embedded. Each set of wedge adjustment structures includes an outer wedge and an inner wedge, which are fitted together by mutually adapting inclined surfaces. The outer wedge can move axially along the rotating shaft. The base 1 is screwed with axial bolts corresponding to the positions of the outer wedges. The ends of the axial bolts abut against the outer wedges. Tightening the axial bolts drives the outer wedges to move axially. The inner wedge is set tightly against the outer circle of the convex stop of the end cover 2 and is constrained to move only radially along the motor and cannot move axially.

[0039] When it is necessary to adjust end cover 2 upwards to compensate for the sag of the shaft, tighten the axial bolts of the lower wedge adjustment structure to drive the outer wedge to feed axially. Through the transmission action of the inclined plane, the inner wedge is pushed radially inwards. The inner wedge pushes against the lower side of the convex stop of end cover 2, causing the end cover to rise as a whole. Simultaneously adjust the axial bolts of the upper wedge adjustment structure so that the upper inner wedge moves upwards with the end cover and remains in contact, achieving bidirectional rigid locking of end cover 2 in both vertical and horizontal directions. Because the inclined plane of the wedge has a self-locking characteristic, it can maintain a stable position under strong vibration conditions on ships after adjustment, without the risk of loosening or displacement, and is suitable for the use requirements of high-power heavy-duty marine motors.

[0040] The marine motor end cover of this invention integrates the bearing assembly and stator into a single stationary unit. Adjusting the vertical offset of the end cover simultaneously corrects the vertical dimensional deviations of the bearing bush fit clearance and the stator-rotor air gap, effectively compensating for the shaft's self-weight-induced deflection and avoiding problems such as concentrated load on the lower side of the bearing bush and oil film instability. It also eliminates unilateral magnetic pull caused by uneven air gap, reducing the risk of unit vibration, rotor rubbing, and bearing burnout. For the exciter structure, the excitation air gap can be calibrated simultaneously to counteract magnetic field imbalance and ensure stable excitation output. It can also offset the accumulation of machining and assembly tolerances, reduce the precision requirements for core component machining, improve the first-pass yield rate, and shorten the production cycle. During operation and maintenance, there is no need to return the entire machine to the factory for repair; clearance calibration and wear compensation can be completed within the confined space of the engine room, reducing downtime and spare parts consumption, lowering the overall life-cycle maintenance cost, and meeting the stringent requirements of long-term, uninterrupted operation of ocean-going vessels.

[0041] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A marine electric machine employing an eccentric end cover, characterized by, The device includes a base, an end cover connected to the base, a stator connected to the end cover inside the base, a bearing connected to the end cover, a rotating shaft connected to the bearing via a bearing bush, and a rotor disposed on the rotating shaft corresponding to the stator. The axial center of the end cover is offset relative to the axial center of the rotating shaft. By adjusting the degree of offset of the end cover relative to the rotating shaft, the fitting clearance between the bearing bush and the rotating shaft, as well as between the stator and the rotor, is adjusted.

2. A marine electric machine employing an eccentric end cover according to claim 1, characterized by, The bearing includes a bearing housing and a bearing bush. The bearing housing is fixedly connected to the end cap, and the bearing bush is embedded and fixed in the inner hole of the bearing housing. An annular fit clearance is formed between the inner wall of the bearing bush and the outer wall of the journal of the rotating shaft. The dimensional deviation of the upper and lower sides of the annular clearance is corrected by the vertical displacement of the end cap.

3. The marine electric machine employing an eccentric end cover according to claim 1, characterized by, The stator is fixedly installed on the end face of the end cover facing the machine base. It generates radial displacement synchronously with the vertical height adjustment of the end cover, and synchronously adjusts the uniformity of the vertical distribution of the gap between the stator and the rotor.

4. The marine electric machine employing an eccentric end cover according to claim 1, characterized by, The base opening has a plurality of connecting holes circumferentially arranged, and the end cover has a vertical slot corresponding to the connecting holes. Bolts pass through the vertical slots and enter the connecting holes to connect the end cover and the base. The vertical height of the end cover can be adjusted through the vertical slots.

5. A marine electric machine employing an eccentric end cover according to claim 4, characterized by The base and the end cover are connected by a stop structure, which includes a concave stop at the opening of the base and a convex stop on the end cover. The cylindrical surfaces on both sides of the convex stop are clearance-fitted with the corresponding inner surfaces of the concave stop. A vertical adjustment gap is reserved between the upper and lower sides of the convex stop and the concave stop to provide displacement space for adjusting the vertical height of the end cover.

6. The marine motor with an eccentric end cap according to claim 1, characterized in that, The stator is an exciter stator, and the rotor is an exciter rotor. The exciter stator moves vertically in sync with the end cover to calibrate the vertical distribution of the excitation air gap, counteract the off-center load of the excitation magnetic field caused by the sag of the shaft itself, and ensure the stability of the excitation output.

7. The marine motor with an eccentric end cap according to claim 1, characterized in that, The axial offset of the end cap relative to the axial shaft is within the range of 0.5-1mm.

8. The marine motor with an eccentric end cap according to claim 1, characterized in that, The base and the end cover are connected by a stop structure, which includes a concave stop at the opening of the base and a convex stop on the end cover. A uniform radial gap is reserved between the concave and convex stops. The upper and lower ends of the end cover are respectively equipped with wedge adjustment structures. The wedge adjustment structures include an outer wedge and an inner wedge that fit together by inclined surfaces. Under the action of an axial bolt, the outer wedge drives the inner wedge to abut against the base along the inclined surface, thereby adjusting the radial gap between the base and the end cover.

Images