Dynamoelectric machine with oil-cooled bearing

Description

[0001] The invention relates to a dynamoelectric rotary machine with at least one oil-cooled bearing.

[0002] Dynamoelectric rotary machines consist of a stator and a rotor, with the rotor being set in rotation by electromagnetic interaction of the energized stator winding system. The drive shaft, which is non-rotatably connected to the rotor, drives a driven machine, such as a compressor or a fan. This drive shaft is positioned in bearings of the dynamoelectric rotary machine. In larger machines, the bearings are preferably oil-cooled. Depending on the speed, temperature, and load of the machine, the oil temperature of the bearings, such as naturally (convection) cooled plain bearings and oil-lubricated rolling bearings, can exceed a specified temperature limit, which impairs operation.

[0003] To limit the oil temperature, an external oil cooling system with a motor-driven pump and a heat exchanger (oil-air cooler with fan or similar) is provided.

[0004] In the event of a power failure (low-voltage line) of the oil cooling system or a failure of the pump or blower motor, the dynamoelectric rotating machine, also known as the main machine (e.g. a high-voltage machine), must be switched off, as safe operation of the main machine can no longer be guaranteed.

[0005] Another disadvantage, however, is that a safe rundown of this main engine (approximately 10 minutes) is no longer guaranteed. Depending on the operating conditions, the oil temperature can rise sharply, causing the oil viscosity to decrease and the required oil film thickness to become too thin to separate the drive shaft from the bearing.

[0006] In these cases, damage to the bearing journal and drive shaft must be expected. Excessive oil and bearing temperatures can damage rolling bearings, for example. In particular, bearing clearance can lead to preloading of the bearing, which increases losses and temperature and ultimately leads to bearing failure.

[0007] Fan-initiated air cooling of a bearing sleeve or the sleeve bearing results in only limited cooling effects and is therefore only suitable in certain operating cases. Redundant power supply systems for the pumps, designed to bridge a power failure, cannot fundamentally resolve the above-described electrical system failure in the cooling system.

[0008] To ensure safe stopping of the dynamo-electric machine, oil reservoirs are sometimes used that are installed higher than the bearings. Continuous operation of the dynamo-electric machine is therefore not possible.

[0009] DE112016004811T5 discloses a dynamoelectric machine with an oil-cooled bearing and a recooler, wherein oil is pumped by a lubricating oil pump which is directly coupled to the drive shaft and the recooler cools the oil by means of air.

[0010] Based on this, the object of the invention is to provide a reliable oil cooling system for the bearings of a dynamoelectric machine, in particular a high-voltage machine.

[0011] The solution to the problem is achieved by a dynamoelectric machine, in particular a high-voltage machine with, an NDE side and a DE side, the DE side facing a work machine to be driven, a stator having a winding system which causes a rotation of a rotor through electromagnetic interaction, which rotor is connected in a rotationally fixed manner to a drive shaft, at least one oil-lubricated bearing (plain and rolling bearing) which guides and / or holds the drive shaft, a cooling system for the oil of the bearing which has at least one recooler and the necessary piping from and to the bearing, the oil being conveyed from, through and to the bearing by means of at least one conveying device which is directly coupled to the drive shaft, so that oil is conveyed when the drive shaft rotates.

[0012] The dynamoelectric machine according to the invention has a cooling system for at least one oil-cooled bearing of its drive shaft, the oil delivery device of which, e.g., an oil pump and / or a blower (e.g., a self-contained fan) or a blower motor, operates independently of an external (auxiliary) power supply. Thus, even in the event of a power failure or a malfunction of one of the electrical devices (motor, switch, cable, etc.), continuous operation of the dynamoelectric rotary machine, i.e., the main machine, is ensured. This also avoids unplanned shutdowns of the main machine, increasing the availability of the dynamoelectric rotary machine.

[0013] The bearing or bearings can be plain or rolling bearings that are oil-lubricated, with the oil in these bearings being circulated and recooled. Likewise, they can be bearing arrangements or bearing combinations comprising locating bearings and support bearings, which are made up of two or more directly adjacent individual bearings in order to be able to absorb the radial and axial forces, such as a locating bearing that has cylindrical roller bearings and four-point contact bearings. Likewise, it can be a locating bearing that has cylindrical roller bearings and an axial ball bearing. Likewise, it can also be a locating bearing in an O-arrangement or X-arrangement. Oil lubrication of a bearing according to the invention can also be achieved with a support bearing in a tandem arrangement.

[0014] Furthermore, the integrated oil cooling system according to the invention can also be retrofitted to existing dynamoelectric rotary machines. The integrated oil cooling system according to the invention is more cost-effective than external cooling devices, among other things, due to the use of existing components.

[0015] The pump assembly includes, among other components, a pump with the necessary connections, a pump bearing assembly, a torque arm, and a shaft journal for coupling to the drive shaft. The pump is driven directly by the drive shaft of the dynamoelectric machine and circulates or pumps the oil from the bearing(s), particularly the plain bearings, to the respective cooling devices and back to the bearing. The drive shaft, shaft journal, and pump shaft are arranged in axial alignment.

[0016] In this case, a pump shaft is arranged axially aligned with the drive shaft, which requires an installation location on the NDE side of the dynamoelectric machine, especially when the distance to a driven machine is short. This also allows for comparatively better accessibility of the pump assembly for maintenance purposes.

[0017] In another design, the pump shaft is aligned parallel to the drive shaft and is driven by a belt or gears from the drive shaft. This also allows for an arrangement on the DE side of the dynamo-electric machine.

[0018] In a further embodiment, the pump shaft and / or a shaft journal as a coupling between the drive shaft and the pump shaft is hollow or at least partially hollow, which reduces the material expenditure and the weight of the conveying device or pump arrangement.

[0019] According to the invention, the oil in the bearings can be cooled down in various ways. The main focus here is also on ensuring that the oil cooling process is as independent of external power supplies as possible.

[0020] In one design, an oil-to-air heat exchanger is used as a recooler. This is particularly advantageous when the dynamoelectric machine is designed as an air-cooled machine. The oil recooler is installed in the air path, preferably at the air inlet side of the machine, but placement at the air outlet from the machine is also possible.

[0021] Likewise, the recooler can be arranged on the NDE side before or after a fan, especially a fan of the dynamoelectric machine. This supports the autonomous operation of the dynamoelectric machine, since rotation of the drive shaft causes rotation of the fan and the pump.

[0022] This is possible for all protection types of the dynamoelectric machine, regardless of whether it is an open, directly ventilated, a completely enclosed machine or a duct-ventilated machine and thus implicitly also a closed machine.

[0023] An open dynamoelectric machine is understood to be a machine into which ambient air is fed, i.e. ambient air is in direct contact with the active parts (e.g. stator, winding system...) of the machine.

[0024] A directly ventilated dynamoelectric machine is defined as a machine in which ambient air does not penetrate the machine. Any air circulated within the machine is cooled by means of add-on coolers, such as tube or plate coolers, or simply by convection.

[0025] Furthermore, the invention is also suitable for the following cooling methods for dynamoelectric machines, including machines in explosion-proof areas, such as mining. In this case, all components of the dynamoelectric machine, such as the housing, piping, etc., must be designed to prevent static charge from building up during operation.

[0026] The inventive design of the oil-cooled bearings is suitable for dynamoelectric machines of the following cooling types:

[0027] These cooling types are: Cooling type IC01 Air-cooled, self-ventilated IC81W Air / water cooler, internal cooling circuit self-ventilated IC86W Air / water cooler, internal cooling circuit externally ventilated IC611 Air / air cooler, internal cooling circuit self-ventilated, external cooling circuit self-ventilated IC616 Air / air cooler, internal cooling circuit self-ventilated, external cooling circuit self-ventilated IC666 Air / air cooler, internal cooling circuit self-ventilated, external cooling circuit forced ventilated TEWAC Closed engine with air / water cooler TEAAC Closed engine with air / air cooler

[0028] The design of the oil-cooled bearings according to the invention is therefore also suitable for dynamoelectric machines of the following types of ignition protection: Type of protection Ex nA Non-sparking engine, Zone 2 Ex px Pressurized encapsulation of the motor, increased safety of the terminal box, Zone 1 Class 1, Division 2 Non-sparking engine

[0029] The design of the oil-cooled bearings according to the invention is therefore also suitable for dynamoelectric machines designed as HVC compact machines with the following cooling types and / or ignition protection types: Cooling type IC411 Fin-air-cooled, self-ventilated IC416 Fin-air cooled, forced ventilated IC71W Water jacket cooled Type of protection Ex nA Non-sparking engine, Zone 2 Ex pe Pressurized encapsulation of the motor, increased safety of the terminal box, Zone 1 Ex e Increased engine safety, Zone 1

[0030] Likewise, the oil-cooled bearings are also generally suitable for dynamo-electric machines with tube cooling type IC511, especially if the cooler is designed as an add-on cooler.

[0031] The oil-cooled bearings are also suitable for a dynamo-electric machine with plate coolers as add-on coolers.

[0032] The recooler can also be located in the airflow that is directed to the dynamoelectric machine by shaft-mounted fans. Likewise, the recooler can be located in the airflow generated, for example, by a separate external fan of the dynamoelectric machine. In this case, the self-sufficient operation of the dynamoelectric machine is only partially achieved.

[0033] If two oil-lubricated bearings hold the drive shaft to the dynamo-electric machine—which will normally be the case except, for example, in a floating drive shaft bearing—if the oil temperature is exceeded in only one of the two bearings, the cooled oil is preferably made available, at least in part, to the warmer bearing first, and only then to the cooler bearing. This can be monitored by sensors that detect the oil temperature and the bearing temperature, and corresponding control valves influence the oil flow.

[0034] Thermal management involves a control system that collects data from multiple sensors and derives measures to optimize the bearing temperature and / or oil temperature. The sensors measure the temperatures of the bearings and / or the oil. Based on this, cooling of the bearings can be forced, for example, via the oil temperature, and / or the operating behavior of the dynamoelectric machine can be influenced, for example, via the speed. In this case, the control valves can, among other things, supplement or add cooled oil from a cooled oil reservoir or mix it with the existing oil.

[0035] Alternatively, only one bearing can be cooled by the oil circulation, preferably the bearing on the DE side. The bearing on the NDE side would be exposed to the airflow from a fan (either internal or external) and thus potentially sufficiently cooled.

[0036] In all cases, the operation of the pump begins with the rotation of the drive shaft of the dynamoelectric machine, i.e. the main machine, and this pump only stops when the main machine comes to a standstill and the drive shaft has a speed of zero.

[0037] In one design, the cooling systems operate independently of any additional power supply, using only the rotation of the drive shaft. In other words, the pump for pumping oil to the bearings, the fans (especially internal fans), or a pump in the recooler's water circuit are independent of any external power supply. Malfunctions in the cooling system's electrical system cannot occur, as they are not present.

[0038] Safe shutdown even in the event of a power failure is ensured by the autonomous cooling system, especially of the bearings.

[0039] The oil cooling system operates independently of the external power supply. This applies to both the oil pump and, if applicable, the pumps of the dry cooler or other cooling devices. A power failure or malfunction will not impair operation or bring the main engine to a standstill.

[0040] Higher availability of the customer's system is ensured. Autonomous oil cooling is more cost-effective than an external cooling system because the complexity and interfaces are significantly reduced compared to conventional systems.

[0041] If additional electrical energy for auxiliary units had to be provided on the dynamo-electric machine, this could possibly be done via a small generator arranged on the drive shaft or shaft journal.

[0042] The invention and advantageous embodiments of the invention are explained in more detail using exemplary embodiments shown in principle; in which: FIG 1 shows a basic longitudinal section of a dynamoelectric machine, FIG 2 shows a side view of a dynamoelectric machine, FIG 3 shows a basic flow equivalent circuit, FIG 3A shows a further flow equivalent circuit, FIG 4 shows a further side view of a dynamoelectric machine, FIG 5 shows a further basic flow equivalent circuit, FIG 6 shows a further side view of a dynamoelectric machine, FIG 7 shows a further basic flow equivalent circuit, FIG 8 shows an exploded view of a pump arrangement, FIG 9 shows a longitudinal section of the pump arrangement, FIG 10 shows a side view of the pump arrangement, FIG 11 shows a detailed view of the bearing of the pump arrangement.

[0043] FIG 1shows a schematic diagram of a dynamoelectric machine 1 in which a stator 41 with a winding system 39 is arranged in a housing 2, wherein the winding system 39 forms a winding head 40 on the end faces of the stator 41. The dynamoelectric machine 1 can be, among other things, a synchronous machine or an asynchronous machine. The dynamoelectric machine 1 can be a high-voltage machine (rated voltage > 1 kV) or a low-voltage machine (rated voltage < 1 kV).

[0044] Electromagnetic interaction with a rotor 42, which is non-rotatably connected to a drive shaft 3, causes the rotor 42 to rotate about an axis 4. An air gap 44 separates the stator 41 and the rotor 42.

[0045] The rotor 42 can be designed as a squirrel cage rotor with a short-circuit cage 43 or as a permanently excited rotor.

[0046] The drive shaft 3 is held and guided in bearings 10, 20, with the bearing 10 being arranged on the non-drive end (NDE) side and the bearing 20 being arranged on the drive end (DE) side of the dynamoelectric machine 1.

[0047] A fan 5 is arranged on the drive shaft 3. It is designed as a self-ventilating fan and, when the drive shaft 3 rotates, causes an air flow into and / or onto the housing 2 of the dynamoelectric machine 1. A pump arrangement 7 is provided in axial alignment with the drive shaft 3, which will be discussed later.

[0048] FIG 2shows a side view of the housing 2 of the dynamoelectric machine 1, with the bearings 10, 20 positioned on the end faces of the housing 2. Furthermore, on the NDE side, in an extension of the drive shaft 3, a fan 5 is arranged, which functions as a self-ventilating fan. On an axially adjoining shaft journal 6, a pump arrangement 7 is provided, which pumps the oil to and from the bearings 10 and 20, among other things, via a recooler 8. Furthermore, the recooler 8 is provided in the intake area or exhaust area of ​​the fan 5, which recools the oil of the bearings 10, 20 that has heated up during operation of the dynamoelectric machine 1. In this case, the cooler is an air-oil heat exchanger. The piping of the oil lines to and from the bearings 10, 20 must be routed as close as possible to the housing 2 to avoid damage to this piping. Air ducts 38 ensure effective air flow for the internal fan.

[0049] The piping of the oil lines consists of plastic or metal pipes, depending on the requirements of the application of the dynamo-electric machine 1.

[0050] The oil lines from and to the bearings 10, 20 can also be laid completely or only partially within the housing 2 of the dynamoelectric machine 1.

[0051] FIG 3shows a basic fluid mechanics equivalent circuit diagram. The oil heated in the bearings 10 and 20 during operation of the dynamoelectric machine 1 is pumped to and from the bearings 10, 20 by a pump 13 of the pump assembly 7 as soon as the drive shaft 3 rotates. This pumping occurs via appropriate piping, i.e., the inlet and outlet lines 11 and 12 to bearing 10, as well as the inlet and outlet lines 21, 22 of bearing 20. In this case, bearing 20 receives the recooled oil via inlet line 22. Bearing 10 receives the oil already heated by bearing 20 as its inlet. However, since bearing 10 is also positioned in the airflow of the internal fan 5, bearing 10 is sufficiently cooled.

[0052] FIG 3Ashows a further embodiment in which only bearing 20, i.e., the bearing on the DE side, receives separate oil cooling according to the invention. Bearing 10 is exposed to the air flow of fan 5 and thus requires no additional cooling.

[0053] FIG 4 shows one of the FIG 2 similar machine 1, but the piping from and to the bearings 10, 20, as explicitly stated in the FIG 5, is constructed differently in order to improve the cooling of the bearing 10. In this case, the bearing 10 is now also explicitly cooled. The heated oil from the bearing 10 and the bearing 20 is brought together and fed together to the pump arrangement 7. From there, the oil is supplied via the recooler 8 in a common line to the two inlet lines 12 and 22 of the respective bearings 10 and 20. By means of a bypass line 31 between these inlet lines 12, 22 and the outlet lines 11, 21, the thermal management and leak protection of the oil cooling of the bearings 10, 20 can be improved if necessary. For this purpose, sensors are provided at least in the bearings 10, 20, as well as in the inlet lines 12, 22 and outlet lines 11, 21.

[0054] The recooler 8 is available in the versions according to FIG 2 and FIG 4designed as an air-oil heat exchanger, which is preferably arranged in the air flow of the internal fan 5. The recooler 8 can also be arranged—in terms of flow technology—after the fan 5. Likewise, the recooler 8 can also be placed at another location next to or above the dynamoelectric machine 1 or anywhere else.

[0055] FIG 6 shows a dynamoelectric machine 1 in a closed design with a water cooling system of the dynamoelectric machine 1 (not shown in detail), so that this subject matter is not covered by the scope of protection of the claims.

[0056] The recooler 8 is water-cooled and integrated into the water circuit of the dynamoelectric machine 1 in series or parallel. An inlet 47 and a return 48 to the machine are provided. The housing 2 is designed to be closed to the outside; only housing ribs (not shown in detail) and / or a water jacket surround the dynamoelectric machine 1. A closed internal cooling circuit is provided, with fans (not shown in detail) inside the machine ensuring air circulation and sufficient heat transfer to the water jacket.

[0057] The corresponding fluidic equivalent circuit diagram according to FIG 7 differs from FIG 5 merely in that the recooler 8 is now not an air-oil heat exchanger, but a water-oil heat exchanger, i.e., the recooler 8 has a water cooling system 47, 48 as a secondary circuit. The water can be provided by a separate circuit or at least partially taken from a main water cooling circuit of the dynamoelectric machine 1. It is also possible for the recooler 8 to be connected in series to the main cooling circuit.

[0058] In the present case, FIG 6 The dynamoelectric machine 1 and the oil cooling system "share" the secondary circuit of the recooler 8.

[0059] FIG 8 shows an exploded view of the essential individual parts of the pump arrangement 7. The pump arrangement 7 has a pump 13, in particular a gear pump, with connections 14 to which the supply and discharge lines to the bearings 10 and 20 can be connected. A mechanical coupling of the pump 13 to the drive shaft 3 is now achieved via a pump shaft 15, which is connected in a rotationally fixed manner via a groove 36 in the shaft journal 6. The shaft journal 6 is arranged in an axial, rotationally fixed extension of the drive shaft 3, preferably on the NDE side of the dynamoelectric machine 1. A pump bearing 33, which is designed in particular as an angular contact bearing and is arranged in a bearing housing 35, supports the pump shaft 15 and the shaft journal 6. A torque arm 34 is arranged in a bearing cover 37 and is supported, for example, on the housing 2.

[0060] FIG 9 shows the pump assembly 7 in its assembled state. It can be seen that the shaft journal 6 is arranged in the axial extension of the drive shaft 3. The pump drive axis and axis 4 of the drive shaft 3 are axially aligned. The shaft journal 6 is inserted into the drive shaft 3 by means of a thread 53. A conical receptacle, which has a relief 49, acts like a rotating

[0061] Joint during circumferential bending. Screws 50 in the bore 52 on the flange 51 of the shaft journal 6 rest on the end face of the drive shaft 3, if necessary, thus enabling fine adjustment. The screws 50 are thus subjected to compressive loads if necessary. To further secure the shaft journal 6 in the drive shaft 3, it is additionally glued into the thread 53.

[0062] Reversing operation of the dynamoelectric machine 1, i.e. changing from left to right rotation, is only possible with a changeover gear axially in front of the pump or a conversion, since the pump can only pump in one direction.

[0063] FIG 10 shows in a side view the pump arrangement 7, the pump 13 with its connections 14 for the inlets and outlets to the bearings 10 and 20. Furthermore, the FIG 10 the torque arm 34, which is attached to a bearing cover 37. Axial movements 45 and radial movements 44 of the drive shaft 3 due to thermal expansion or vibrations of the dynamoelectric machine 1 can be absorbed by the torque arm 34.

[0064] FIG 11shows a detailed view of the arrangement of the shaft journal 6 to the pump shaft 15. The pump shaft 15 is connected to the shaft journal 6 via a groove 36 in a rotationally fixed manner. Angular contact ball bearings 33 are inserted into a bearing housing 35 and held by a bearing cover 37, which also includes the torque support.

[0065] Such dynamoelectric machines 1 are used primarily in industrial environments as drives for compressors, pumps, and condensers. It is crucial to maintain as trouble-free operation as possible.

Claims

1. Dynamoelectric machine (1), in particular high-voltage machine, with an NDE side and a DE side, wherein the DE side faces a processing machine to be driven, a stator (41) which has a winding system (39) which effects a rotation of a rotor (42) by way of electromagnetic interaction, which rotor (42) is connected to a drive shaft (3) in a rotationally fixed manner, at least one bearing (10, 20) lubricated with oil which guides and / or holds the drive shaft (3) a cooling system for the oil of the bearing (10, 20), which has at least one recooler (8) and the required pipework therefor from and to the bearing (10, 20), wherein a conveyance of the oil from, through and to the bearing (10, 20) takes place by means of at least one conveying facility, which is directly coupled to the drive shaft (3), such that oil conveyance takes place when the drive shaft (3) is rotated, wherein the cooling system of the oil works independently of an external power supply, wherein the conveying facility is preferably arranged on the NDE side, wherein the recooler (8) recools the oil by means of air, characterised in that in the case of a dynamoelectric machine (1) cooled by means of air, a recooling of the oil of the bearing (10, 20) is provided by way of an oil-air heat exchanger as the recooler (8), which is arranged in the air path of the dynamoelectric machine (1) cooled by means of air, wherein the dynamoelectric machine (1) cooled by means of air has an inherent fan (5), in whose immediate intake and / or outlet region the recooler (8) is arranged.

2. Dynamoelectric machine (1) according to claim 1, characterised in that the drive shaft (3) and shaft of the conveying facility axially align.

3. Dynamoelectric machine (1) according to claim 1 or 2, characterised in that thermal management of at least the bearing (10, 20) is provided, which detects the oil temperature and / or the bearing temperature and provides measures derived therefrom.

4. Dynamoelectric machine (1) according to one of the preceding claims, characterised in that the conveying facility is a pump (7).

5. Dynamoelectric machine (1) according to one of the preceding claims, characterised in that the recooling of oil can be used in dynamoelectric machines (1) of different cooling type and / or ignition protection type.

6. Dynamoelectric machine (1) according to claim 5, characterised in that the recooler (8) is arranged on the NDE side.

7. Dynamoelectric machine (1) according to claim 1, characterised in that the conveying facility is driveable by way of a drive pulley / toothed gear.

8. Dynamoelectric machine (1) according to claim 7, characterised in that the conveying facility is arranged at the NDE side.

9. Dynamoelectric machine (1) according to claim 1, characterised in that the oil-air heat exchanger is arranged directly upstream or downstream of the fan (5) of the dynamoelectric machine (1).

10. Dynamoelectric machine (1) according to one of claims 2 to 9, characterised in that a pump shaft (15) is mechanically coupled to the drive shaft (3) by way of a shaft neck (6).

11. Use of a dynamoelectric machine (1) according to one of the preceding claims 1 to 10, in particular as a drive for compressors, pumps etc.