JPH0654469A - Ring-shaped stator core provided with cooling promotion means - Google Patents

Abstract

PURPOSE: To enable prevention of deterioration in cooling effect by separating cooling air channels in the axis and the radial direction formed in a stator core of a generator constituted of a plurality of lamination sheets, at the intersections between the axial channels and the radial channels and thereby preventing the cooling airs in the axial and the radial channels from being mixed up. CONSTITUTION: A stator core 20 of a rotary machine is made by stacking, in the axial direction, a plurality of laminated sheets 171a punched in the shape of a comb teeth. The stator core 20 has stator poles 174 projecting from a yoke 175 at equal intervals and hollow stator slots 172 formed between each two stator poles 174. In the stator core 20, a plurality of axial cooling air channels 160, and radial cooling air channels 170 are formed. The axial channels 160 are made by making holes parallel to a shaft in the core 20. The radial channels 170 are made by bending the laminated sheets 171b at the ends of the adjacent packs 176 of laminated sheets 171a and are so formed that cooling airs in the radial channels and the axial channels may not mix up at the intersections between the axial channels 160 and the radial channels 170. Owing to this structure, the deterioration in cooling effect caused by the ratio of cooling air in the axial channels to that in the radial channels can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to a device for cooling a stator core of a large rotating electric machine, and more particularly to a device for cooling an end region of the stator core.

[0002]

2. Description of the Related Art Rotating electric machines, such as large generators, are manufactured compactly because they are designed to have a high speed, a small diameter, and a relatively short length. It is hermetically sealed to contain the medium. Due to these design features, it is difficult to cool the windings and stators of the generator wires. Even though the efficiency of such generators is very high, there is some heat loss and therefore it is necessary to pass a relatively large amount of cooling gas through the generator to dissipate the heat generated by the losses.

For example, heat loss results from ohmic resistance in the stator windings and eddy currents in the stator core that occur when current flows through the windings. The loss in the latter case is reduced by constructing the core with a very thin laminated sheet. Nevertheless, since eddy currents are generated, it is necessary to dissipate the resulting heat loss and keep the temperature rise of the stator within the required design limit. For this purpose, cooling gas is circulated in the generator through cooling passages provided in the stator core. To provide such passages, the stator is divided into separate packs of laminated sheets. This separation between the stator packs is accomplished by vent fingers or rectangular block structural members located in the space between adjacent packs. The passages formed between the vent fingers are commonly referred to as "radial passages" or "radial cooling passages". Other independent passages may be formed, for example, arcuate cutouts commonly referred to as "axial passages" or "axial cooling passages" that extend laterally through the laminated sheets of each stack. It is good to provide.

The problems associated with stator core cooling are particularly pronounced in the stator core end regions of such generators.
In a large synchronous machine, a magnetic field is generated by the current in the end-turn portion of the rotor winding and in the end portion of the stator winding, and the magnetic field coupling produces a magnetic flux directed in the axial direction. This axial magnetic flux penetrates the end portion of the stator core in the direction perpendicular to the core laminated sheet and causes a circulating current in the laminated sheet in the end region.
The corresponding heat loss is significant and causes an excessive temperature rise in the end region of the stator core. Both radial passages and axial passages are formed here in order to allow the cooling medium to flow in the stator core end region. However, only the axial passage is usually formed in the central portion of the stator core. This is because the temperature rise in this central part is less than in the stator end area.

A typical stator core is annular and tubular, extending substantially the length of the generator. The stator core has an inner inner peripheral surface forming an inner surface and an outer outer peripheral surface forming an outer surface, and a stator core body is formed between them. In a typical generator cooling system, the axial passages run parallel to the inner and outer surfaces and extend the entire length of the stator core. The radial passage extends through the stator core perpendicular to the inner and outer surfaces and from the outer peripheral surface to the inner peripheral surface. A cooling gas (eg, hydrogen) is circulated in the axial and radial passages. In a typical cooling scheme, a forced convection device, such as a fan, located in the end region of the rotor forces gas into the generator. The gas flows through the fan and is cooled by a cooling device located adjacent to the fan.
The gas circulation flow path is then branched to cool various parts of the stator. One gas branch flow (radial gas flow) flows around the stator end adjacent to the fan and along its outer surface, then inwardly, in the radial direction provided in the stator end region. It flows into the passage. The gas then flows through the radial passages to the inner surface and then axially along the inner surface back to the fan. Another branch flow (ie, axial gas flow) causes the gas to flow toward the other end of the stator and then into the axial passages provided in the stator core, whereupon the stationary Flow axially through the child. Eventually, the gas exits the stator end area adjacent the fan and returns to the fan.

[0006]

In the end region of the conventional stator core, the radial passages and the axial passages intersect each other to mix the gases in the separate passages. This mixing will reduce the efficiency of the cooling system. This is because it is difficult to predict the gas flow direction. Such gas mixing has the undesirable effect of overcooling, or overcooling, the end regions of the stator, which can shorten the life of the generator and interfere with its operation.

Therefore, it is a problem in the prior art to cool the end region of the stator core where two independent passages of the same cooling system intersect to solve the drawback due to gas mixing.

Therefore, there is a need for a cooling device in the end region of the stator core, which keeps two independent cooling passages of the same cooling system independent of each other at their intersection.

A generator including a device for cooling an end region of the stator core by providing crossing radial passages and axial passages in the stator core for receiving a cooling medium. A stator core is disclosed. As is well known, the stator core is composed of a plurality of packs which are formed of a plurality of laminated sheets and which are adjacent to each other and are spaced apart from each other. In the present invention, the existing technology incorporates a device for sealing and isolating the intersection of the axial and radial passages in the stator core. As an example of accomplishing this, the outer laminate sheet of the pack is preformed, the outer laminate sheet is bent to form an opening that coincides with the axial passage and the outer laminate sheet is firmly engaged with the adjacent pack. Thus isolating the axial passage from the radial passage at the intersection. As another example, to achieve such isolation, conduits are placed along the axial passages between adjacent laminated sheets.

It is an object of the present invention to provide an improved stator in which the end areas of the stator core are cooled.

[0011]

In view of this object, the gist of the present invention is an elongated annular stator core having means for promoting cooling of an end region thereof, the cooling promoting means comprising:
A plurality of spaced-apart packs having a plurality of laminated sheets forming a stator core, wherein radial cooling passages are formed between adjacent packs and each pack penetrates and An axial cooling passage intersecting with the radial cooling passage is provided, and the cooling promoting means further comprises:
Barriers located between adjacent packs and provided at each intersection of the radial and axial cooling passages to isolate the axial and radial cooling passages from each other. The stator core is characterized by including.

The subject matter of the present invention will become apparent from the following detailed description of the preferred embodiment, which is shown by way of example only in the accompanying drawings.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings (the same reference numerals indicate the same parts in the drawings), FIG. 1 shows a typical large rotating electric machine, for example, an airtight housing containing a laminated stator core 20. A sealed generator (indicated generally by 1) including 10 is shown. The housing 10 has a generally circular and tubular housing body 30 whose ends are sealed by generally circular sides 40a, 40b. Stator core 20
The (generally cylindrical) is generally annular in cross-section and extends substantially the entire length of the housing 10. The stator core 20 includes an inner peripheral surface 50, an outer peripheral surface 60, and an end surface or an end portion 2 extending between the inner peripheral surface 50 and the outer peripheral surface 60.
5a and 25b are included. The stator core 20 includes a plurality of stator windings 7 of a type well known in the art housed in a stator slot 172 (see FIG. 2) provided therein.
It has 0. Further, as shown in FIG. 1, a generally cylindrical rotor 80 is supported by bearings (not shown) provided in the housing 10 and extends through the stator core 20 in the length direction. , Conventional field winding (not shown)
Is equipped with. The rotor 80 is generally circular in cross section and extends substantially the entire length of the housing 10. The rotor 80 also includes a shaft portion 90 having a turbine end 100 connected to a turbine (not shown) and an exciter end 110 connected to an exciter (not shown). The fan 1 is installed at the turbine-side end 100 of the rotor 80.
Twenty is attached. Generally, fan 120 has a plurality of rotating vanes 130 circumferentially spaced around rotor shaft 90 and serves to pump a cooling medium, such as hydrogen, into generator 1. Adjacent to the turbine-side end portion 100 of the rotor shaft 90, cooling means 140 for cooling the circulating hydrogen is installed. The cooling means 140, eg a heat exchanger, comprises a suitable vessel (not shown) containing a cooling medium, eg water, which cooling water flows through such vessel. The cooling water flows in and out of the generator through the housing body 30 through the outlet pipe 151 and the inlet pipe 150, and the pipes 151 and 150 are connected to the container through the turbine side end portion 100 of the housing body 30. A plurality of separate axial passages 160, which define cooling passages through the stator core 20, extend the length of the stator core 20. Thus, the axial passage 160 axially penetrates both ends and the central portion of the stator core 20. In this example, different radial passages 170 are provided only in each of the end regions of the stator core 20.

Continuing to refer to FIG. 1, the fan 120
Directs a cooling gas, ie hydrogen, from the exciter side end 110 of the stator core 20, through the stator core 20, across the fan 120 and through it towards the cooling means 140, where the cooling means 140 Hydrogen is cooled when flowing in a heat exchange relationship with this. More specifically, hydrogen passes through the heat exchanger 140 and then branches to cool various portions of the stator core 20. To initiate such branching, gas flows around the end 25b of the stator core, traverses the outer periphery 60 of the stator core 20, and the outer periphery 60 and housing body 30.
Flows in the opposite direction between and. The gas flow is at the turbine end 10
At 0, it branches into two flow paths. The first such flow (radial flow) is generated in the radial passage 17 from the outer peripheral surface 60 side.
0 flows out from the inner peripheral surface 50 side, but the gas flows along the inner peripheral surface 50 by the fan 120 and the turbine side end portion 100.
Sent forcibly. The second such channel runs along the outer peripheral surface 60 towards the exciter end 110, from which the gas further branches into two separate directions for cooling of the stator core. The flow in the first direction (radial flow) enters the radial passage 170, flows through it, and the inner peripheral surface 50
However, the gas (hydrogen) is forced by the fan 120 along the inner peripheral surface 50 toward the turbine-side end 100. The flow in the second direction (axial flow) proceeds along the end surface 25a, flows into the axial passage 160, and flows out from the axial passage 160 toward the turbine-side end portion 100. At the turbine-side end 100, all of the gas returning from the axial passages 160 and the radial passages 170 and the gas portion flowing along the inner peripheral surface 50 are the turbine-side end 100 of the stator core 20.
It joins and mixes at. The fan 120 sends the returning gas (hydrogen) across the fan 120, after which the gas stream is circulated along the same path described above.

Referring now to FIG. 2, the stator core 20
Is a stack formed by stacking the laminated sheets 171 and includes the above-mentioned end faces 25a and 25b (FIG. 1). The laminated sheets 171 for forming the stator core 20 are stacked to form a plurality of generally rectangular hollow stator slots 172 spaced apart from each other.
72 extends in the radial and axial directions of the stator core and opens toward the inner peripheral surface 50 of the stator core 20, and terminates at a radial interval from the outer peripheral surface 60 of the stator core 20. ing. Each pair of adjacent stator slots 172 define a slot surface 173 therebetween, the slot surfaces being oriented parallel and concentric with the outer peripheral surface 60. The portion of the stator core 20 located between adjacent stator slots 172 is commonly referred to as "stator teeth" 174, and the portion of the stator core 20 that extends radially from the outer peripheral surface 60 to the slot surface 173 is generally It is called the "stator yoke" 175. Conventional windings (not shown) are typically housed within the stator slots 172 to form the conductors in which the induced voltage develops. The stator core 20 is formed of packs 176 located at a plurality of intervals, and each pack 176 includes a laminated sheet 171 (see FIG. 3).
(See) is formed by stacking. As best seen in FIG. 2, arcuate notches or openings (which appear to be circular in this example) aligned with each other extend laterally through all of the laminated sheet 171. Thus, the axial passage 160 is formed. Thus, the axial passage 160 extends longitudinally through both the stator teeth 174 and the stator yoke 175. At both the turbine end 100 and the exciter end 110, pairs of vent fingers 190 fit snugly between the spaced packs 176 to form a plurality of radial passages 170. waiting. The vent finger 190 constitutes a supporting means for supporting the pack 176, and also serves as a spacing holding means for maintaining the pack 176 in a predetermined separation relationship. Thus, pack 1
The spacing of 76 from each other provides a radial passage 170 between adjacent packs 176. The radial passages 170 extend from the inner peripheral surface 50 of the stator teeth 174 to the outer peripheral surface 60, and the vent fingers 190 and the pack 17 are provided.
Located between 6 and 6.

Continuing to refer to FIG. 2, in a typical stator core 20, the outer sheet 171 b of each pack 176.
Is slightly wider and thicker than the laminated sheets 171a located therein, and the inner laminated sheet 171a is
It consists of most of the volume of. The end portions of the stator core 20 where the axial passages 160 and the radial passages 170 intersect each other are further divided, and a part of the stator core 20 is divided into end faces 25.
A plurality of pistoy slots 195 extending from a, 25b to a predetermined distance in the radial direction.
To have. However, most of the stator core 20 only passes through the plurality of inner laminated sheets 171a in the radial direction and the axial direction.
It should be noted that it is configured without the 5. The pistol lot 195 opens into the inner peripheral surface 50 of the stator 80 and radially terminates from the outer peripheral surface 60 of the stator core 20 to meet electromagnetic requirements. The piste slots 195 are arranged along the stator core 20 between the adjacent vent fingers 190 or in a state in which there is a space between the end faces 25a and 25b and the adjacent vent fingers 190. Laminated sheet 17
No. 1 is positioned at both ends of the pistol slot 195, and the laminated sheet 171 is solid so that gas does not leak into the radial passage (however, the axial passage 160
except for). The pistio lot 195 is located at a predetermined distance above the axial passage adjacent to the inner peripheral surface 50,
The inner peripheral surface 50 side is sealed by arranging a sealing means, for example, an epoxy material, in the hollow portion extending from. With the arrangement described above, the gas is any gas that flows through the axial passages 160 into each pistio lot 195 and along which it will not escape. By encapsulating the gas in the Pistosphere 195, the loss of hydrogen is limited to a negligible amount.

As best seen in FIG. 3, in the end regions of the stator core 20, where both axial passages 160 and radial passages 170 are present, the gases typically tend to mix at the intersections. According to the present invention, the outer laminated sheet 171b belonging to at least a part of the pack 176 is bent outward or dimpled to surround the arcuate notch 200 of the outer laminated sheet 171b adjacent to d. Prior to bending, the outer laminate sheet 171b need not have openings aligned with the axial passages 160 and is typically formed of a generally flat continuous sheet. Outer laminated sheet 171b
The adjacent stack 1 in the outer laminated sheet area that covers the axial passage 160 and abuts the adjacent laminated sheet snugly.
It may be deformed or bent outwards toward 76 and the outer laminate sheet 171b may be cut in place to form an unobstructed conduit that aligns with the axial passage 160, or The area covering the axial passage 160 may be precut or recessed. The dimpled portion of the laminated sheet 171b completely defines the arcuate cutout 200 to form an essentially isolated tunnel-like flow path extending from one dimpled sheet 171b to the arcuate cutout 200 of an adjacent sheet 171b. It is enclosed in a sealed state. This dimpling or embossing provides a barrier provided between the radial passage 170 and the axial passage to isolate the two passages 170, 160 from each other.

Referring now to FIGS. 2 and 4, there is provided a pistelot 195 which penetrates the pack 176 and is approximately 180 ° on each side of the arcuate cutout 200 as described above. You can see that it is extended. Axial passage 1 near each Piste Yeslot 195
60 and radial passage 170
They are hermetically separated and isolated from each other in the same apparatus and method as in the portion not containing 95 (see Figure 3).

Referring now to FIG. 5, the stator core 20
Includes a stack as described above consisting of laminated sheets 171a, 171b that form a stator tooth 174 with an axial passage 160 and a radial passage 170 provided therethrough. As described above and as best seen in FIG. 5, hollow pistol lots 195 are provided at the ends of the stator core 20 within the stator teeth 174, the pistol lots 195 comprising a plurality of inner plies. The inner peripheral surface 5 of the stator core 20 penetrates only the laminated sheet 171a in the radial direction and the axial direction.
Although it is open to the inside of 0, it terminates at a radial interval from the outer peripheral surface 60 of the stator core 20. The pistol slot 195 contains sealing means, such as an epoxy material, as described above, to prevent gas from flowing radially from the stator teeth 174 into the housing 30. Pisto Yeslot 195 has adjacent vent fingers 1
Between 90 and between the end faces 25a, 25b and the adjacent vent finger 190, the laminated sheets 171 at both ends of the pistol lot 195 can be made solid so that hydrogen does not escape in the radial direction. . With such a seal, the loss of hydrogen through the pitslot can be controlled to a negligible amount.

Referring to FIG. 6, in another embodiment of the present invention, tube 220 may be plugged into axial passage 160,
The intersection of the axial passage 160 and the radial passage 170 is bridged to form a tunnel-shaped annular member that hermetically separates the two passages 160, 170. The pipe 220 includes an inner peripheral surface 230, an outer peripheral surface 240, and an inner peripheral surface 230 and an outer peripheral surface 2.
It has a thickened portion 250 between 40 and 40, and the constituent material may be an insulating material such as ceramic or glass.
The ends of the outer peripheral surface 240 of the pipe 220 are adjacent to each other in the stack 1.
The outer peripheral and inner laminate sheets 171a and 171b, which are firmly attached to and abut the peripheral surface of the axial passage 160 of 76, overlap the inner peripheral surface of the axial passage 160. I am configuring. The tube 220 may also be used either in the area of the stator tooth 174 on the stator tooth 174 or on the portion of the stator tooth 174 without the piston tooth 210.

Referring to FIG. 7, in yet another embodiment of the present invention, tubular sleeve 260 includes axial passage 16
The zero and radial passages 170 are shown in sealed isolation. A sleeve 260 having an inner peripheral surface 270, an outer peripheral surface (not shown), and a thickened portion (not shown) between the inner peripheral surface 270 and the outer peripheral surface is provided between the outer sheets 180 of the adjacent stacks 176. It has a length substantially equal to the spacing. The sleeve 260 is preferably made of stainless steel, for example, which is inserted into the axial passage 160 and which also positions and aligns the inner peripheral surface 270 of the sleeve 260 and extends through the adjacent packs 176. It cooperates with the inner peripheral surface 270 of 160 to form a continuous surface and passage. The wall of the sleeve 260 firmly abuts the outer laminate sheet 171b of the adjacent stacks 176 and forms a seal that isolates the two passages 160, 170 and prevents gas mixing. The sleeve 260 may also be used either in the area of the stator tooth 174 on the stator tooth 174, or on the portion of the stator tooth 174 without the piston tooth 210.

[0022]

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a generator with some parts removed for clarity.

FIG. 2 is a perspective view of a longitudinal cross section of a part of a stator end portion region showing adjacent stator packs.

FIG. 3 shows means for isolating radial and axial passages formed in a stator pack according to the present invention.
FIG. 3 is a vertical cross-sectional perspective view of two adjacent stator packs of FIG.

FIG. 4 shows means for isolating radial and axial passages formed in a stator pack according to the present invention.
Figure 2 is a perspective longitudinal cross-sectional view of two other adjacent stator packs of Figure 1 with a Pisutoye strobe crossing the pack.

FIG. 5 is a partial longitudinal cross-sectional perspective view of a portion of a stator end region showing a stator tooth having a piston rod.

FIG. 6 is a vertical cross-sectional perspective view of a modified example of the present invention, which shows a modification means for isolating the radial passage and the axial passage formed in the stator pack.

FIG. 7 is a perspective view in vertical section of another embodiment of the present invention showing still another modification means for isolating the radial passage and the axial passage formed in the stator pack.

[Explanation of symbols]

 20 Stator core 50 Inner peripheral surface 60 Outer peripheral surface 160 Axial passage 170 Radial passage 171 Laminated sheet 174 Stator teeth 176 Pack 190 Vent finger 195 Pistellosto 220 Pipe 260 Sleeve

Claims (6)

[Claims] 1. An elongated annular stator core having means for promoting cooling of an end region thereof, the cooling promoting means having a plurality of spacings having a plurality of laminated sheets forming the stator core. Radial cooling passages are formed between adjacent packs, including packs placed side by side, and each pack is provided with an axial cooling passage that passes through the packs and intersects with the radial cooling passages. The cooling promoting means is further provided between the adjacent packs and is provided at each intersection of the radial cooling passage and the axial cooling passage, and the axial cooling passage and the radial cooling passage are provided. A stator core comprising barriers for isolating the passages from one another. 2. The barrier is formed of at least one sheet of one of the packs, the sheet being bent outwardly from the pack toward an adjacent pack to enclose an axial cooling passage. 2. The stator core of claim 1 wherein the radial cooling passages and the axial cooling passages intersecting each other are thereby isolated from each other. 3. The barrier is a tube having an end and an outer surface, the tube bridging the intersection of the axial cooling passage and the radial cooling passage, the end of the outer surface of the tube. A stator core according to claim 1, wherein the stator cores are mounted in corresponding packs to isolate the radial cooling passages and the axial cooling passages from each other. 4. The barrier is a sleeve having ends, the length of the sleeve being substantially equal to the spacing between adjacent packs, each end of the sleeve having a radial cooling passage and an axial direction. The stator core of claim 1, wherein the stator cores abut each pack to isolate the cooling passages from each other. 5. Stator core according to claim 1, characterized in that vent fingers for supporting the pack are arranged in the radial cooling passages. 6. The radial cooling passage is provided only in an end region of the stator core.
Stator core.