Centrifugal compressor oil pump and motor coaxial integrated device and lubricating method

Abstract

The invention relates to a centrifugal compressor oil pump and motor coaxial integrated device and a lubricating method, the device comprises a motor shaft, a high-speed shaft pinion and an oil pump, the motor shaft is coaxially fixed with a bull gear, and the bull gear is meshed with the high-speed shaft pinion; the high-speed shaft pinion drives the oil pump shaft through a transmission bevel gear set which is coaxially arranged, the transmission bevel gear set comprises a bevel pinion and a bevel gear wheel, the bevel pinion is coaxially and fixedly connected with the high-speed shaft pinion, and the bevel gear wheel is coaxially and fixedly connected with the oil pump shaft. The oil pump shaft and the motor shaft of the centrifugal compressor are integrally designed, so that the oil pump can synchronously run once the motor is started, and the oil pump cannot stop working as long as the motor shaft is not completely stopped, so that the lubrication requirement of the bearing is uninterruptedly guaranteed, and the service life of the bearing is prolonged. And the abrasion risk of the transmission assembly caused by shutdown of the oil pump is fundamentally eliminated.

Description

Technical Field

[0001] The present invention relates to the technical field of marine air-conditioning centrifugal compressors, and specifically to a device and lubrication method for realizing synchronous operation of an oil pump and a motor through a coaxial integrated design of bevel gears, which is particularly applicable to centrifugal compressor systems that require highly reliable lubrication in harsh environments such as ships. Background Art

[0002] During the long-term use of centrifugal chiller units, it has been found that there are situations where the unit suddenly loses power, the oil pump stops working while the bearings are still rotating, or the oil pump suddenly fails due to a fault or other reasons, resulting in the obstruction of the oil supply system and causing bearing wear. Although the above sudden faults can be avoided through circuit design, accidents are inevitable. For ships using centrifugal chiller units, to further improve the reliability of mechanical operation, other solutions need to be found.

[0003] Traditional centrifugal compressors need to provide lubrication to bearings and gears through an independent oil pump, and there are the following problems:

[0004] 1. Dependence on circuit design: The start and stop of the oil pump are controlled by the circuit. Once power is cut off or a fault occurs, lubrication is interrupted, leading to bearing wear.

[0005] 2. Structural redundancy: In the prior art, the oil pump shaft is separated from the motor shaft, and an additional driving device is required (such as the high-pressure oil pump is independently arranged in CN 117028549B), increasing the complexity of the system and the failure points.

[0006] 3. Poor environmental adaptability: In the ship environment, salt spray, vibration, etc. are likely to shorten the service life of traditional oil pumps (such as the environmental protection design is not mentioned in CN206860765U).

[0007] The existing patent document CN206860765U reduces axial friction through a thrust disc, but does not solve the problem of synchronism between the oil pump and the motor shaft; CN117028549B proposes temperature control of lubricating oil, but an external high-pressure oil pump is required, and the risk of oil pump shutdown cannot be avoided. Summary of the Invention

[0008] Based on the above problems, the present invention proposes a coaxial integrated device and lubrication method for a centrifugal compressor oil pump and motor. The integrated design of the centrifugal compressor oil pump shaft and the motor shaft can ensure that once the motor starts, the oil pump runs synchronously, ensuring that as long as the motor shaft does not completely stop, the oil pump will not stop working, thereby continuously ensuring the lubrication requirements of the bearings and fundamentally eliminating the risk of wear of transmission components caused by oil pump shutdown.

[0009] To achieve the above object, the technical solution of the present invention is: a coaxial integrated device for a centrifugal compressor oil pump and motor, including a motor shaft, a high-speed shaft pinion, and an oil pump. The motor shaft is coaxially fixed with a large gear, and the large gear meshes with the high-speed shaft pinion; the high-speed shaft pinion drives an oil pump shaft through a coaxially arranged transmission bevel gear set. The transmission bevel gear set includes a small bevel gear and a large bevel gear. The small bevel gear is coaxially and fixedly connected with the high-speed shaft pinion, and the large bevel gear is coaxially and fixedly connected with the oil pump shaft.

[0010] Further, the oil pump base is fixed to the compressor base, and its oil suction port is located in the lubricating oil sump of the compressor base.

[0011] Further, the lubricating oil sump of the compressor base is connected to an oil cooler.

[0012] Further, a radial bearing is provided on the front side of the small bevel gear. The bearing material is salt spray-resistant stainless steel, and a rubber shock pad is provided between the bearing seat and the base.

[0013] Further, the oil pump outlet is connected to the original lubrication pipeline through a three-way valve, and the three-way valve switches to the oil pump for oil supply after the motor is started.

[0014] Further, the tooth surfaces of the large bevel gear and the small bevel gear are nitrided, the surface hardness is ≥800HV, and the tooth root bending fatigue strength is ≥300MPa.

[0015] Further, the meshing clearance of the transmission bevel gear set is 0.05 - 0.1mm, and the coaxiality error is calibrated by a laser alignment instrument to be ≤0.02mm.

[0016] Further, the impeller of the oil pump adopts a two-way oil suction design, and the impeller surface is coated with a polytetrafluoroethylene anti-corrosion layer.

[0017] A lubrication method based on the above coaxial integrated device for a centrifugal compressor oil pump and motor includes the following steps:

[0018] (1) Before the compressor is started, pre-lubrication is carried out through the original oil pump;

[0019] (2) After the motor is started, the transmission bevel gear set drives the oil pump to run synchronously, and the three-way valve switches to the oil pump for oil supply;

[0020] (3) During the operation of the oil pump, the gear vibration signal is monitored in real time. If the amplitude exceeds the threshold, an alarm is triggered.

[0021] The beneficial effects of the present invention are:

[0022] 1. The integrated design of the centrifugal compressor oil pump shaft and the motor shaft can ensure that once the motor is started, the oil pump runs synchronously. As long as the motor shaft does not completely stop, the oil pump will not stop working.

[0023] 2. The device can continuously ensure the lubrication requirements of the bearings, fundamentally eliminating the risk of wear of the transmission components caused by the shutdown of the oil pump.

[0024] 3. Enhance the operational reliability of the centrifugal compressor.

[0025] 4. Reduce the failure rate of the centrifugal compressor.

[0026] 5. Ensure sufficient lubrication of the bearings and gears of the centrifugal compressor during operation.

[0027] 6. The oil pump shaft and the motor shaft of the centrifugal compressor are integrally designed, greatly saving labor costs and maintenance expenses, and at the same time enhancing the commercial value. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic diagram of the coaxial integrated design of the oil pump motor of the centrifugal compressor of the present invention - a bevel gear coaxial oil pump. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The present invention will be further described below in conjunction with the drawings and embodiments.

[0030] To prevent the sudden power failure of the compressor and the stoppage of the oil pump, the present invention is designed to add a bevel gear oil pump to achieve linkage with the motor shaft. Since the current oil pump speed is less than the compressor motor speed, bevel gear transmission is added. One of the bevel gears rotates coaxially with the pinion on the high-speed shaft. Since the pinion on the high-speed shaft meshes with the large gear on the motor shaft, the oil pump can be synchronized with the motor shaft. The added oil pump is installed on the bracket and placed at the bottom of the machine body for easy oil suction of the oil pump.

[0031] To facilitate the oil suction of the newly added oil pump and its linkage with the motor shaft, a pair of bevel gears are added. The newly added oil pump is placed on the base and connected to the compressor body by a flange. At the same time, a bearing is added in front of the smaller bevel gear as a support.

[0032] As Figure 1 shown, for the device of the integrated design of the oil pump shaft and the motor shaft of the centrifugal compressor, on the basis of the existing centrifugal compressor with gear transmission, the following parts are mainly added: a large bevel gear, a small bevel gear, a bearing, an oil pump, and an oil pump base.

[0033] The motor shaft 1 is coaxially fixed with the large gear 4, and the large gear 4 meshes with the pinion 2 on the high-speed shaft; the pinion 2 on the high-speed shaft drives the oil pump shaft 6 through the coaxial transmission bevel gear set 5.

[0034] The transmission bevel gear set 5 includes a large bevel gear 5a and a small bevel gear 5b. The small bevel gear 5b is coaxially fixedly connected with the pinion on the high-speed shaft, and the large bevel gear 5a is coaxially fixedly connected with the oil pump shaft 6.

[0035] Preferably, the oil pump 3 is fixed to the compressor base through the oil pump base 9, and its oil suction port is located in the lubricating oil sump of the compressor base.

[0036] Preferably, the lubricating oil sump of the compressor base is connected to the oil cooler 7.

[0037] Preferably, a radial bearing 8 is provided on the front side of the small bevel gear 5b. The bearing material is salt spray resistant stainless steel, and a rubber vibration damping pad is provided between the bearing seat and the base.

[0038] Preferably, the outlet of the oil pump 3 is connected to the original lubrication pipeline through a three-way valve, and the three-way valve switches to supply oil from the oil pump 3 after the motor starts.

[0039] Preferably, the tooth surfaces of the large bevel gear 5a and the small bevel gear 5b are nitrided, the surface hardness is ≥800 HV, and the tooth root bending fatigue strength is ≥300 MPa.

[0040] Preferably, the meshing clearance of the transmission bevel gear set is 0.05 - 0.1 mm, and the coaxiality error is calibrated by a laser alignment instrument to be ≤0.02 mm.

[0041] Preferably, the impeller of the oil pump adopts a two-way oil suction design, and the surface of the impeller is coated with a polytetrafluoroethylene anti-corrosion layer.

[0042] The lubrication method of the present invention:

[0043] Before the compressor is started, the original oil pump of the centrifugal compressor is first used to pre-lubricate the bearings, gears, etc. Then the motor starts and the motor shaft begins to rotate. At this time, bevel gear transmission is added. One of the bevel gears rotates coaxially with the small gear on the high-speed shaft. Since the small gear on the high-speed shaft meshes and rotates with the large gear on the motor shaft, the oil pump can be synchronized with the motor shaft. The added oil pump is installed on the bracket and placed at the bottom of the machine body to facilitate the oil pump to suck oil. At this time, the original oil pump can stop working, and the outlet of the newly added oil pump is connected to the outlet of the original oil pump pipeline to replace the original oil pump to supply oil.

[0044] Since a pair of bevel gears is added, the bevel gear transmission system needs to be designed:

[0045] 1. Research on the speed matching of the oil pump bevel gear

[0046] The oil pump is connected to the high-speed shaft of the compressor. The speed of the high-speed shaft is higher than that of the oil pump. Therefore, geometric parameters need to be set and size calculations need to be carried out to match the oil pump speed.

[0047] (1) Size calculation: The following geometric parameters need to be calculated - modulus, transmission ratio, pitch cone angle, pitch diameter, addendum height, dedendum height, total tooth height, clearance, addendum circle diameter, dedendum circle diameter, cone distance, tooth width, tooth width coefficient, tooth tip angle, tooth root angle, root cone angle, crown cone angle, etc.

[0048] (2)Regarding the back teeth and equivalent number of teeth: Since the tooth profile on the back cone is extremely similar to the tooth profile of the spherical involute, the tooth profile on the back cone is used to replace the tooth profile of the spherical involute. The back cone is unfolded into a plane to obtain a pair of sector gears with the length of the back cone generatrix as the pitch circle radius, and then it is supplemented to a complete gear, thereby obtaining the equivalent gear and the equivalent number of teeth of the bevel gear.

[0049] 2. Strength analysis of the oil pump bevel gear

[0050] During the meshing transmission process of the bevel gear, it needs to bear loads, and the strength needs to be checked to ensure the normal operation of the gear, including the calculation of transmission strength and the calculation of tooth root bending fatigue strength.

[0051] Using an analysis method similar to that of cylindrical gears, the normal load Fn on the teeth of the straight bevel gear is regarded as concentrated on the average pitch circle;

[0052] The bending fatigue strength of the teeth of the straight bevel gear is calculated according to the average equivalent cylindrical gear;

[0053] The tooth surface contact fatigue strength of the straight bevel gear is calculated according to the average equivalent cylindrical gear.

[0054] 3. Research on the operation reliability of the oil pump bevel gear

[0055] In order to verify the rationality and accuracy of the gear design, reliability tests are required for verification. After the test, all gears are disassembled and inspected to check the gear operation conditions.

[0056] After the prototype is assembled, first conduct an idling test, then charge the refrigerant for a full-load test, and at the same time install a vibration measuring instrument. The full-load test needs to run from low load to full load for a total of 200 hours, and arrange 10 tests of stopping and restarting. Finally, disassemble and inspect the compressor to check the wear conditions of the gears, bearings and shafts.

[0057] During the design process of the device of the present invention, the influences of environmental conditions such as salt spray, mildew, inclination, sway, vibration, electromagnetic compatibility, etc. are fully considered, and it can meet the requirements of the actual ship use environment.

[0058] Example 1:

[0059] As Figure 1 shown, the motor shaft drives the large gear through a key connection. The large gear meshes with the small gear on the high-speed shaft, and the transmission ratio is 3:1. The small gear on the high-speed shaft is coaxially connected to the small bevel gear 5b with a module of 3 mm and 15 teeth, which drives the large bevel gear 5a with a module of 3 mm and 30 teeth, and the transmission ratio is 1:2. The radial bearing at the front end of the small bevel gear 5b is made of SUS440C stainless steel, and a neoprene vibration damping pad is provided between the bearing seat and the base. The oil pump is fixed by a flange, and the oil suction port extends deep into the bottom of the oil sump of the base.

[0060] Technical effects: The bevel gear drive enables the oil pump and the motor shaft to be synchronized. The vibration damping pad reduces the impact of ship vibration, and the stainless steel bearing improves the salt spray resistance performance.

[0061] Embodiment 2:

[0062] The oil outlet of the oil pump is connected to the original lubrication pipeline through a three-way valve, and the valve body switching response time ≤ 0.5 s. The tooth surface of the large bevel gear 5a is treated by ion nitriding, with a hardness of 820 HV and a tooth root bending strength of 320 MPa.

[0063] Technical effects: The quick switching of the three-way valve ensures uninterrupted lubrication, and the high-hardness design of the gear extends the service life to more than 10,000 hours.

[0064] Reliability verification: A 200-hour full-load test is carried out. The vibration sensor monitors that the amplitude ≤ 0.1 mm, and the gear wear amount is < 0.01 mm after 10 starts and stops.

[0065] Innovation points of the present invention:

[0066] Through the coaxial integrated design of bevel gears, the synchronous operation of the oil pump and the motor shaft is realized, ensuring the continuity of lubrication. And through gear strength checking, environmental adaptability design and multiple reliability verifications, the system stability is significantly improved.

[0067] Technical effects of the present invention:

[0068] 1. The oil pump and the motor shaft operate synchronously. When powered off, the oil supply can still continue, and the risk of bearing wear is reduced by 90%;

[0069] 2. The gear strength checking and anti-corrosion design of the bevel gear double the system life compared with the traditional structure;

[0070] 3. The two-way impeller and the vibration damping structure are adapted to the inclined and swaying conditions of the ship.

Claims

1. An integrated device with a coaxial oil pump and motor for a centrifugal compressor, characterized in that, It includes a motor shaft, a high-speed shaft pinion, and an oil pump. The motor shaft is coaxially fixed with a large gear, and the large gear meshes with the high-speed shaft pinion. The high-speed shaft pinion drives an oil pump shaft through a coaxially arranged transmission bevel gear set. The transmission bevel gear set includes a small bevel gear and a large bevel gear. The small bevel gear is coaxially and fixedly connected to the high-speed shaft pinion, and the large bevel gear is coaxially and fixedly connected to the oil pump shaft.

2. The coaxial integrated device of the centrifugal compressor oil pump and motor according to claim 1, characterized in that, The oil pump base is fixed to the compressor base, and its oil suction port is located in the lubricating oil sump of the compressor base.

3. The coaxial integrated device of the centrifugal compressor oil pump motor according to claim 2, characterized in that, The lubricating oil sump of the compressor base is connected to an oil cooler.

4. The coaxial integrated device of the centrifugal compressor oil pump motor according to claim 1, characterized in that, A radial bearing is provided on the front side of the small bevel gear. The bearing material is salt spray-resistant stainless steel, and a rubber vibration damping pad is provided between the bearing seat and the base.

5. The coaxial integrated device of the centrifugal compressor oil pump motor according to claim 1, characterized in that, The oil pump outlet is connected to the original lubrication pipeline through a three-way valve, and the three-way valve switches to the oil pump for oil supply after the motor starts.

6. The coaxial integrated device of the centrifugal compressor oil pump and motor according to claim 1, characterized in that, The tooth surfaces of the large bevel gear and the small bevel gear are nitrided, the surface hardness is ≥800HV, and the tooth root bending fatigue strength is ≥300MPa.

7. The coaxial integrated device of the centrifugal compressor oil pump and motor according to claim 1, characterized in that, The meshing clearance of the transmission bevel gear set is 0.05 - 0.1mm, and the coaxiality error is calibrated by a laser alignment instrument to be ≤0.02mm.

8. The coaxial integrated device of the centrifugal compressor oil pump and motor according to claim 1, characterized in that, The impeller of the oil pump adopts a two-way oil suction design, and the impeller surface is coated with a polytetrafluoroethylene anti-corrosion layer.

9. A lubrication method for the coaxial integration device of the centrifugal compressor oil pump and motor according to any one of claims 1 - 8, comprising the following steps: (1) Before the compressor starts, pre-lubricate through the original oil pump; (2) After the motor starts, the transmission bevel gear set drives the oil pump to run synchronously, and the three-way valve switches to the oil pump for oil supply; (3) During the operation of the oil pump, continuously monitor the gear vibration signal, and trigger an alarm if the amplitude exceeds the threshold.

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