Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2000-08-31
2001-11-13
Ramirez, Nestor (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S043000
Reexamination Certificate
active
06316859
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a rotating electric machine such as a turbine generator.
A cylindrical rotor of a rotating electric machine such as a conventional turbine generator is provided with a magnetic winding, which excites the generator when the rotor receives a DC current from an exciting power source.
The rotor is provided with a plurality of slots for inserting magnetic windings therein at equally spaced intervals in the circumferential direction thereof, and teeth are installed between the slots. Within each slot, the magnetic winding is disposed in layers and held. When the magnetic winding is energized, the temperature of the conductor may sometimes rise to not less than 100° C. Therefore, in order to prevent a decrease in the strength of a resin material for electric insulation, as in an example described in JP-A-60-190135 and an example described in JP-A-9-285052, a plurality of gas vent holes are provided in the magnetic winding in the lamination direction thereof and a gas, such as air and hydrogen gas, is caused to flow through these holes, thereby cooling the conductor. In order to vent this gas in the radial direction of the rotor, gas vent holes with a size larger than those provided in the magnetic winding are formed in a creepage block for electric insulation and in wedges for fixing the magnetic winding and the creepage block. The holes in the magnetic winding have a shape of an ellipse that is long in the axial direction of the rotor and, therefore, in order to cause the gas to flow with efficiency, a gas vent groove with a cross section of a circular arc or a rectangular cross section, is formed in a continuous shape in the axial direction of the rotor on the face of a creepage block abutting against the magnetic winding, thereby providing a passage of the cooling gas. Usually, this gas vent groove is simultaneously machined (cut) when a creepage block is cut from a glass-reinforced epoxy resin plate.
In a rotating electric machine such as a turbine generator, the operating temperature of a magnetic winding is apt to rise in association with large capacity design of the rotating machine, causing the problems of the necessity for improving the cooling capacity and the necessity for keeping the strength of a resin material for insulation.
SUMMARY OF THE INVENTION
An object of the invention is to provide a rotating electric machine in which the cooling capacity is improved by increasing the width and depth of a gas vent groove formed in a creepage block.
Another object of the invention is to provide a rotating electric machine in which a fracture of a creepage block that is fabricated from a resin containing reinforcing fibers is prevented near the face of the creepage block abutting the magnetic winding.
The present inventors have concentrated their energies on research in order to solve these problems. As a result, paying attention to the fact that when an attempt is made to improve the cooling capacity by increasing the width and depth of the gas vent groove, the area of the contact face between the creepage block and the magnetic winding decreases, resulting in an increase in the pressure of the contact face between the creepage block and the magnetic winding due to a centrifugal force acting during rotation, and the fact that when the capacity of a rotating electric machine is increased, the amount of thermal expansion of the magnetic winding in the axial direction of the rotor during rotation also tends to increase due to a rise in the temperature of the conductor by energization, the inventors found that high stress concentration occurs near the face of the creepage block abutting against the magnetic winding, which abutting face is subjected to a shearing force in the transverse direction (the axial direction of the rotor) while subjected to a high pressure (in the radial direction of the rotor). Furthermore, the inventors found the problem that in the glass-reinforced epoxy resin fabricated by laminating glass fiber cloths in the plate thickness direction (the radial direction of the rotor), which epoxy resin has so far been used in the creepage block, reinforcing fibers near the face of the creepage block abutting against the magnetic winding are cut during the forming of the gas vent groove from a flat laminate (a sheet material) by machining (cutting) in the plate thickness direction and a slip occurs on an interlayer slip face of the laminate (the face that is sandwiched between reinforcing fibers and is mainly composed of a resin susceptible to a shearing force) in a portion where stresses are concentrated, with the result that the creepage block is fractured near its face abutting against the magnetic winding.
The above problems are solved, for example, to by providing rotating electric machines having the following constituent features.
In an example, in a creepage block of a rotating electric machine fabricated from a resin material containing reinforcing fibers, the reinforcing fibers, which are expressed by drawn lines in which fine patterns of fibers, such as twists, capable of being identified by enlargement are omitted, are continuously disposed to form straight lines and smooth curves along the contour of a gas vent groove. According to this example, during a slip of the interlayer slip face present between the reinforcing fibers that occurs due to a shearing force in the axial direction of a rotor which acts on the creepage block due to a temperature change of the rotor, the slip area is larger than the interlayer slip area in a case where the reinforcing fibers expressed by drawn lines are cut near the machined gas vent groove, are straight lines, and are disposed parallel to a tangent to the circumference of the rotor in the middle of the width of the face abutting against the magnetic winding (a case where a normal of the interlayer slip face is perpendicular to the center line of the rotor). In this case, therefore, the shearing force per slip area decreases, thereby making it possible to prevent a slip fracture between the reinforcing-fiber layers.
In another example, in a creepage block of a rotating electric machine fabricated from a resin material containing reinforcing fibers, drawn lines of an interlayer slip face on a cut section, which drawn lines are expressed by omitting fine patterns on the interlayer slip face capable of being identified by enlargement, such as wrinkles, are continuously disposed to form straight lines and smooth curves along the contour of the gas vent groove. According to this example, during a slip of the interlayer slip face present between the reinforcing fibers that occurs due to a shearing force in the axial direction of a rotor which acts on the creepage block due to a temperature change of the rotor, the slip area is larger than the slip area in a case where the drawn lines of interlayer slip faces on the cut section are straight lines near the machined gas vent groove and are disposed parallel to a tangent to the circumference of the rotor in the middle of the width of the face abutting against the magnetic winding. In this case, therefore, the shearing force per slip area decreases, thereby making it possible to prevent a slip fracture between the reinforcing-fiber layers.
In another example, a plurality of prepreg sheets, in which an unset resin material is caused to be contained in reinforcing fibers which have been woven beforehand, are stacked in layers, and a creepage block of a rotating electric machine is formed by sandwiching these prepreg sheets stacked in layers between a flat press plate and a press plate having projections fitting the shape of gas vent groove. According to this example, near the gas vent groove, the interlayer slip face of the laminate, which slips due to a shearing force in the axial direction of the rotor which acts on the creepage block due to a temperature change of the rotor, is composed of flat and curved surfaces and the area of the slip face is larger than the area of the interlayer slip face of a laminate in a case whe
Aoyama Hiroshi
Ejima Hidehiro
Hattori Toshio
Igarashi Yoshiyuki
Addison Karen
Antonelli Terry Stout & Kraus LLP
Hitachi , Ltd.
Ramirez Nestor
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