Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K9/00—Arrangements for cooling or ventilating
  • H02K9/14—Arrangements for cooling or ventilating wherein gaseous cooling medium circulates between the machine casing and a surrounding mantle
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02K—DYNAMO-ELECTRIC MACHINES
  • H02K9/00—Arrangements for cooling or ventilating
  • H02K9/02—Arrangements for cooling or ventilating by ambient air flowing through the machine
  • H02K9/04—Arrangements for cooling or ventilating by ambient air flowing through the machine having means for generating a flow of cooling medium
  • H02K9/06—Arrangements for cooling or ventilating by ambient air flowing through the machine having means for generating a flow of cooling medium with fans or impellers driven by the machine shaft

Definitions

• the present invention relates to electrical rotating machines .
• the invention relates to an electrical rotating machine comprising a machine housing with an internal cooling circuit, where the machine exhibits inlet opening means and outlet opening means for a gaseous coolant such as, for example, air.
• the invention relates to a device adapted to admit a gaseous coolant but to block the passage of liquids.
• the invention relates to a method in such an electrical rotating machine with a machine housing comprising an internal cooling circuit, where the machine is arranged with inlet opening means and outlet opening means for a gaseous coolant such as, for example, air.
• Electrical low-voltage rotating machines are usually designed in industry with respect to the desired performance, for motor operation as well as for generator operation.
• the development within this field currently proceeds towards a need of increasingly higher output of power and torque for given standard sizes of electrical rotating machines. This implies that manufacturers of such machines, primarily because of the prevailing hard price competition, are pressed to increase the performance of the machines.
• Such a develop- ment of electrical rotating machines towards an increasingly higher degree of utilization, that is, an increased output of power and torque leads to increasingly greater temperature loads in conventionally designed machines. This makes heavy demands on cooling.
• En electrical rotating machine comprises machine parts such as a rotor, a stator, a machine housing, bearings, a rotor winding and a stator winding, a drive shaft and possibly an internal and/or external cooling fan.
• Internal machine parts are, for example, rotor and stator and external machine parts are, for example, machine housing and drive shaft.
• An electrical rotating machine usually comprises at least one cooling circuit.
• the energy losses for example winding losses, iron losses and friction losses in an electrical machine, increase the temperature of the various parts of the machine and on the surface of the machine.
• the rotor and the stator are nor- mally responsible for the majority of the losses of the electrical rotating machine and are therefore extra important to cool.
• One factor that normally limits the size of a machine is the temperature of the winding.
• the temperature in the winding insulation determines the service life of the winding.
• Heat may be discharged in various ways, by conduction, convection and radiation. Different transport methods and coolants may be utilized in different parts of an electrical rotating machine.
• An electrical rotating machine is usually designed with the purpose of having a good thermal dissipation ability from the winding to the coolant.
• the temperature of the machine depends on the losses of the machine and how efficient the cooling of the machine is.
• Air is a common coolant in an electrical rotating machine.
• Another common coolant is water.
• Pollutants in the machine may cause an electric or mechanical fault, or overheating of the electrical rotating machine due to the pollutants clogging the inlet and/or outlet of the cooling circuits.
• the machine housing is usually chosen with a view to providing sufficient protection from mechanical influence.
• the machine housing should also protect the machine from penetration of pollutants such as water, other liquids such as oil, and dust such as coal dust and cement dust.
• One further requirement is protection against contact and penetrating solid objects, such as dust.
• Such machines are intended, for example, for an industrial environment where pollutants and temporary splashing of water occur.
• TEFC closed jacket-cooled machines
• ODP Open Drip Proof
• the machine is protected against a finely divided jet of spraying water if the machine is located at an angle that is two- thirds of a right angle in relation to the water jet, which only results in primitive protection against the intake of liquids. This is referred to here as a drip-proof machine.
• An open machine cannot be located in extremely wet and fouled environments . Water penetrating into an electrical rotating machine causes corrosion on the bearing, which increases the risk of a bearing breakdown. It is also necessary to protect the electrical insulation on the windings and the electrical winding connections from penetrating water.
• US patent 5,557,153 discloses an open machine. From this document it is known to filter air before leading it into the machine and utilizing it for cooling via a filter which also, in certain designs, filters away water vapour. The object is to provide a controlled air flow.
• this document only concerns filtering away air with a conventional dust filter, and these dust filters are of an unwieldy, voluminous nature and only manage a flow of air at a low velocity.
• filtering takes place in a separate unit in the base of the machine, which is a bulky and cost-demanding solution. Therefore, because of the expense, such filtering is not suitable for series manufacture. In addition, because of the demand for space, and hence a high cost, such filtering is carried out in large machines only.
• the machine has an external protective device preventing contact with movable parts inside the machine.
• the machine is also protected against the introduction of solid objects. Dust is allowed in a quantity that does not have an adverse effect on the operation of the machine, for example at a maximum underpressure of 20 millibars and where the internal air volume is changed 60 times per hour. This is referred to here as being dust-protected.
• a closed jacket-cooled machine may be located in wet and polluted environments, as opposed to an open machine.
• One problem with a closed machine is that the transport of the motor losses is deteriorated compared with an open machine. For this reason, a closed machine must, for a given shaft power, be manufactured with a larger quantity of active material compared with an open machine in order to discharge the heat to reduce the losses. This results in an increased manufacturing cost for the machine.
• the object of the invention is to improve the cooling in an electrical rotating machine of the kind where water cannot be accepted inside the machine such that said problems are overcome or at least reduced.
• the solution in an electrical rotating machine of the kind described in the preamble to claim 1, is to ensure that at least one inlet opening is covered by a layer which is adapted to admit the coolant but to block passage of liquids.
• the electrical rotating machine comprises a machine housing.
• the machine housing comprises an internal cooling circuit.
• the machine exhibits inlet opening means and outlet opening means for a gaseous coolant such as, for example, air.
• a layer arranged to admit the coolant but to block the passage of liquids is allowed to cover at least the inlet opening means.
• the coolant is harmless to the internal machine parts.
• the coolant is brought into contact with the internal parts of the machine and is utilized for cooling these. This transforms a non-water-protected and dust- protected open internal cooling circuit into a water-protected and dust-protected open internal cooling circuit.
• the machine is cooled by external air that passes through the machine.
• the air then passes through the internal cooling circuit in the machine.
• the internal cooling circuit comprises, for example, the air gap of the machine and cooling channels in the stator and rotor.
• the cooling air di- rectly cools the internal parts of the machine.
• a machine with a device according to the invention has a better ability to discharge heat from the rotor and the stator than an electrical rotating machine that only discharges the heat via the casing. This reduces the thermal load on the internal machine parts for an electrical rotating machine with a device according to the invention compared with a closed jacket-cooled machine designed according to the state of the art for a given power and a given pole number. The order of magnitude of the reduction of the thermal load is 10-15%. This also reduces the cost of production.
• an electrical rotating machine comprising a device according to the invention has a low natural weight. Also, the total size of equipment comprising a machine with a device according to the invention is reduced.
• the layer is a hydrophobic filter and/or an oleophobic filter.
• a hydro- phobic filter is utilized to provide the passage of gas, preferably air, under a low pressure drop and at a large air flow, but to prevent the passage of water.
• a hydrophobic material has a low-energy surface. The material is not wetted by the water, but a drop of water placed on a low-energy surface retains its drop-like shape and rolls over the surface instead of running if the surface is inclined. Water avoids forming a contact surface with the individual parts of the hydrophobic filter since these surfaces have a high energy.
• the surface tension of the water serves to retain the individual water droplets when in contact with the individual parts in the hydrophobic filter.
• the layer is pre- ferably shaped as a network of wires with very small holes.
• the filter preferably has a hydrophobic surface by a surface treatment. This makes the filter water-proof but not vapour- proof.
• An oleophobic filter is active against oil in the same way as a hydrophobic filter is active against water.
• the layer is arranged to block the passage of solid particles.
• the main intention is to block liquid but it is also an advantage to get rid of solid particles such as dust.
• the machine also fulfils the requirements for an electrical rotating machine that is classified as a closed jacket-cooled machine, which means that it is flush-proof and dust-protec- ted.
• the layer is a filter with a hole size in the interval of 0.5 to 120 urn. This causes the filter to block water droplets.
• a filter manages to exclude a water column of at least 1 dm.
• the layer is a fil- ter with a hole size in the interval of 0.5 to 40 urn.
• a filter manages to exclude particles of a permissible order of size according to the CEI/IEC 60034-5 standard, 4 th edition, classes IP55 and IP65.
• the layer is a woven filter.
• the threads are interwoven according to know technique for textile manufacture. In this way, the netting is regular and the size of the holes limited by the threads is well-defined.
• the layer has an inclined surface, such as conical or curved. This has the advantage that water being blocked and hence collected by the layer is influenced by the gravitation and that the water droplets easily roll off the layer. The same is true of dust particles. In addition, when running off, the water carries dust particles along with it.
• said layer comprises a second filtering layer with coarser holes of the first layer, wherein the second filtering layer is arranged on the outside of the first layer in relation to the machine. This protects the first layer from mechanical damage.
• the layer has a supporting layer arranged as a support for the layer. This reduces the load on the layer, which extends the service life of the layer.
• the layer is arranged in a frame. This makes the layer easy to install in an electrical rotating machine.
• the layer is arranged to be replaceable. This is an advantage when the layer is clogged.
• At least one outlet opening is covered by said layer. This facilitates the location of the machine in an environment .
• said inlet opening and/or outlet opening is arranged in a casing and/or an end surface. This makes it possible, after the application, to actively guide the cooling air against that part of the machine which is to be primarily cooled, preferably coil ends, on the windings. This location also makes the layers easily accessible.
• the layer is an external filter. This location is advantageous when the inlet opening and/or the outlet opening of the machine is arranged on the inside of, for example, a throttle device or a mechanical protective device. This facilitates a location of the layer on the surface of the machine .
• An electrical rotating machine with a device according to the invention is intended for applications in industrial environments where a large power output is required.
• the machine is also intended for applications in industrial environments with a certain expected degree of fouling, which, for example, implies a controlled level of water, both in liquid form and in vapour form, in the ambient air.
• the ambient air also has a controlled level of small particles such as, for example, dust.
• the device may, as such, be used both on existing machines and on newly manufactured machines.
• Claims 15-23 describe preferred embodiments of a device comprising at least one layer that is arranged to admit a coolant but to block the passage of liquids. This results in advantages corresponding to those disclosed by the electrical rotating machine described in the various embodiments in the claims depending from claim 1.
• Claims 24-35 describe advantageous embodiments of a method in different embodiments of the electrical rotating machine comprising at least one layer that is arranged to admit a coolant but to block the passage of liquids. This results in advantages corresponding to those disclosed by the electrical rotating machine described in the various embodiments in the claims depending from claim 1.
• Figure 1 shows a preferred embodiment of an electrical rotating machine according to the invention
• FIG. 2 shows another preferred embodiment of an electrical rotating machine according to the invention
• FIG. 3 shows a further preferred embodiment of an electrical rotating machine according to the invention
• Figure 4a shows a preferred embodiment of a device according to the invention
• Figure 4b shows another preferred embodiment of a device according to the invention.
• C gaseous coolant for example air
• inlet opening means la inlet opening for gaseous coolant lb inlet opening for gaseous coolant 3a first end shield
• cooling flange 70 device comprising a layer
• Figure 1 shows an embodiment of an electrical rotating ma- chine according to the invention comprising a rotor 20 comprising a driving end D and a non-driving end N, a stator 30, a machine housing 40 comprising a casing 4, a first end surface 50a comprising a first end shield 3a and a second end surface 50b comprising a second end shield 3b.
• the electrical rotating machine comprises cooling flanges 60, an external fan 8, an internal fan 12, inlet opening means 1 with inlet openings for inlet la, lb of a gaseous coolant C, in this case air, outlet opening means 7 with outlet openings 7a, 7b for outlet of the gaseous cool- ant C, a mechanical protective device 11, a roughing filter 14, and a device comprising a layer 71 arranged to admit a coolant.
• the machine also comprises an internal cooling circuit V and an external cooling circuit 0.
• the electrical rotating machine is built up with the preferably cylindrical stator 30 being stationary.
• the rotor 20 is rotatably arranged in the stator.
• the stator is in turn fitted into the machine housing 40.
• the machine housing preferably comprises a cylindrical casing 4 and a circular first end surface 50a at one end of the cylinder and a circular second end surface 50b at the other end of the cylinder.
• the first end shield 3a is built into the first end surface 50a and the second end shield 3b is built into the second end surface 50b.
• the casing and the two end surfaces comprising end shields form an internal cooling circuit V.
• cooling flanges are arranged at the casing, parallel to the drive shaft A of the rotor.
• an external fan 8 At the rotor on the non-driving end N outside the first end surface and outside the internal cooling circuit, there is arranged, for example, as in this case, an external fan 8 that accompanies the rotational movement of the rotor.
• the external fan drives the air flow in the external cooling circuit 0 and the internal cooling circuit V.
• an internal fan 12 on the non-driving end of the rotor but inside the first end surface.
• the internal fan drives the air flow in the internal cooling circuit.
• the internal fan also accompanies the rotational movement of the rotor.
• the air into the fan 8 first passes through a roughing filter 14.
• the task of the roughing filter is to separate larger particles from the incoming cooling air. This reduces the risk of clogging of the layer.
• the layer is protected from external influence with a mechanical protection device 11.
• the machine is arranged with an inlet opening means 1 for air in the non-driving end, with inlet openings la on the first end surface and inlet openings lb on the casing.
• the driving end of the machine is arranged with an outlet opening means 7 for air outlet, with outlet openings 7a on the second end surface and outlet openings 7b on the casing near the driving end.
• a device is arranged comprising a layer 71 adapted to admit a coolant, in this case air.
• the cooling air then flows from the non- driving end to the driving end.
• the cooling air is pressed from the external fan 8 to the internal fan 12.
• the air flow from the fan is distributed between the external cooling circuit V and the internal cooling circuit 0. Air is conducted into the non-driving end of the electrical rotating machine and flows out on the axially opposite side of the electrical rotating machine.
• FIG. 2 An additional example of an advantageous embodiment of the invention is shown in Figure 2, where an electrical rotating machine has the layer placed outside the casing of the electrical rotating machine.
• the electrical rotating machine is built up in the same way as the machine in the above-men- tioned embodiment.
• a throttle device is mounted at each end of the machine.
• the object of the throttle devices is to equalize the air flow between the cooling circuits.
• the first throttle device 13a is located on the casing at the non-driving end N with the aim of controlling the ingress of air through the inlet opening lb into the casing
• a second throttle device 13b is located on the casing at the driving end D after the egress of air through the outlet opening 7b in the casing.
• the first end surface is also arranged with inlet openings la in the same way as described above.
• the second end surface 50b has no outlet openings .
• a layer 71 is ar- ranged which is adapted to admit a coolant, in this case air. Otherwise, the machine has the same coolant circulation as has been described above.
• the inlet opening means may either be placed on the driving end of the electrically rotating machine, or on the non- driving end of the electrically rotating machine.
• FIG. 3 Still another example of an advantageous embodiment of the invention is shown in Figure 3 with reversed direction of the cooling air through the machine compared with the embodiments shown, that is, from the driving end D to the non- driving end N of the machine.
• an external fan 8 is arranged in this case, said fan accompanying the rotational movement of the rotor.
• the external fan creates an underpressure which maintains the air flow in the external cooling circuit 0 and the internal cooling circuit V.
• a mechanical protective device 11 is arranged outside the fan blades to protect the fan.
• the inlet opening means 1 for air is arranged at the driving end, with inlet openings la on the casing.
• the outlet opening means 7 is arranged at the non-driving end of the machine with outlet openings 7a arranged on the first end surface.
• a throttle device 13 is arranged on the casing at the driving end D for the purpose of controlling the inflow of air through the inlet opening la.
• a layer 71 adapted to admit a coolant, in this case air is arranged in the same way as described above .
• Figure 4a shows an advantageous embodiment of a device 70 comprising a layer 71 that is adapted to admit a coolant but to block the passage of liquids.
• the device is intended to be placed so as to cover at least one opening in an inlet opening means or an outlet opening means in an electrically rotating machine.
• the layer is arranged, for example, as in this case, comprised in a frame 72.
• Figure 4b shows a further advantageous embodiment of a device 70 comprising a layer 71 that is adapted to admit a coolant but to block the passage of liquids.
• the layer is conically shaped.
• the filter is preferably mounted on the machine in such a way that the force of gravity contributes to remove water and dirt particles from the layer.
• the layer is comprised in a frame 72.
• the surrounding air also has a controlled level of small particles, such as, for example, dust.
• small particles such as, for example, dust.
• One example of a usual industrial environment is that the size of particles occurring in the air is larger than 40 u,m.
• the quantity of particles is lower than 0.5 kg/m 3 of air.
• the cooling air has a humidity that is below 80%.
• the inlet openings of the air- inlet means and the outlet openings of the air-outlet means may be located in different combinations on the axial end surfaces of the electrical rotating machine, at the end shields of the electrical rotating machine, and/or on the casing of the electrical rotating machine. A different location of a fan or fans or a different number of fans is possible.
• the direction of the cooling air through the ma- chine may be from the driving end of the machine to the non- driving end or inversely, or the air may circulate on the side of the machine.
• the layer may also be designed as a randomly shaped network.
• the layer may also be designed as a fabric of extruded polymer that in itself is hydrophobic. The invention is intended for all kinds of machines.

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Motor Or Generator Cooling System (AREA)

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Family Applications (1)

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Cited By (7)

Citations (4)

• 2003
  • 2003-10-01 SE SE0302608A patent/SE526870C2/sv not_active IP Right Cessation
• 2004
  • 2004-09-29 WO PCT/SE2004/001395 patent/WO2005031948A1/en active Application Filing

Patent Citations (4)

Non-Patent Citations (1)

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