JPS6141392Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention reduces the thermal stress that occurs inside the rotor coil when it receives heat due to power supply in a large rotating electric machine such as a turbine generator.
This invention relates to a rotor for a rotating electrical machine that prevents plastic deformation.

A conventional example of a slot portion of a rotor in a large rotating machine will be described with reference to FIG. In the slot 12 of the rotor 11 are rotor coils 13 and 14 and turn separators 15 and 16 for insulating the turns of each coil.
In addition, a slot armor 17 is installed on the wall of the slot 11 to insulate the rotor coils 13 and 14 from the ground.
is provided. Further, since the rotor coils 13 and 14 are subjected to centrifugal force due to rotation, a rotor wedge 18 is attached to the upper part to hold the rotor coils 13 and 14, and an insulating block is installed between the rotor coil 13 and the rotor wedge 18 to insulate them. 19 has been inserted.

When the rotating machine is operated and the rotor 11 rotates, the rotor coil 13 and the like are subjected to centrifugal force and are pressed diametrically outward (upward in FIG. 1) of the rotor 11. Furthermore, as the rotor coil 13 and the like are energized as the rotor 11 rotates, their temperature increases.
Thermal expansion occurs in the direction of the rotation axis of rotor coil 1.
Since the top surface of 3 is in contact with the insulating block 19,
A restraining force due to friction acts between the rotor coil 13 and the insulating block 19, preventing thermal expansion.

Here, the frictional restraint force is expressed mathematically as F=μ・N, where F: Frictional restraint force μ: Friction coefficient between the rotor coil 13 and the insulating block 19 N: Centrifugal force acting on the rotor coil 13 be. Therefore, the centrifugal force N acting on the rotor coil 13
is constant, the frictional restraint force F is the rotor coil 1
3 and the insulating block 19, and it is desirable that the friction coefficient be low.

The insulating block 19 is generally a laminate of polyester or epoxy based glass cloth. The coefficient of friction μ between the insulating block 19 and the rotor coil 13 increases as the temperature rises, and when the temperature of the insulating block 19 exceeds the thermal deformation temperature, its value increases rapidly. Some materials, such as the rotor coil 13, have low yield strength, but in such cases, if thermal expansion is restricted,
Compressive plastic deformation may occur, causing serious trouble to rotating electric machines.

Furthermore, since the insulating properties of the rotor coil 13 and the insulating block 19 deteriorate when moisture adheres to them, consideration must be given to the adhesion of moisture. For this reason, in order to reduce moisture adhesion and frictional force, a water-repellent material such as silicone oil is applied to the rotor coil 1.
3 and an insulating block 19 was proposed. However, silicone oil cannot remain between the rotor coil 13 and the insulating block 19 for a long period of time when the rotor coil 13 undergoes repeated thermal expansion and contraction and is subjected to strong centrifugal force pressure. Ta. Although silicone rubber has good heat resistance, its high coefficient of friction makes it unusable.

In addition to the above, it has been proposed to tape the rotor coil 13 with an insulating sheet having a low coefficient of friction, such as a heat-resistant polymer paper sheet (trade name: Nomex, manufactured by DuPont). In this case, the sheet taped to the rotor coil 13 moves in the axial direction due to the heating and cooling cycle of the rotor coil 13 and becomes twisted. Normally, the insulating block 19 is divided, so if the difference in expansion coefficients between the rotor coil 13 and the insulating block 19 is large, the taped sheet will deviate from its normal arrangement and eventually may lead to a situation where the system does not function properly. Furthermore, in the case of a hydrogen-cooled rotor, etc., the taping may clog the ventilation holes, making it impossible to implement the method.

Further, unlike the stator coil and the like, the rotor coil 13 is characterized in that the centrifugal force of the rotor coil 13 acts on the insulating block 19 below the rotor wedge 18. Especially in large, high-speed rotating electric machines such as turbine generators, the acceleration of the rotor surface is 5000 g.
(g: gravitational acceleration), the centrifugal force due to the rotor coil's own weight acting on the insulating block can exceed 7 kg/mm ² in terms of surface pressure.

On the other hand, a polytetrafluoroethylene (trade name: Teflon) sheet is known as a material with a low coefficient of friction, and a configuration has been proposed in which this sheet provides sliding action between the insulating block 19 and the rotor coil 13. .

However, polytetrafluoroethylene has a drawback in its creep properties, and when placed under extremely high pressure as described above, it creeps in the plane direction and becomes thinner, and over time it tends to protrude in the width direction of the insulating block 19. Eventually, there will be no space between the insulating block 19 and the rotor coil 13. Therefore, the sliding action cannot be achieved satisfactorily.

The present invention was developed from this point of view, and its purpose is to provide an extremely simple structure other than sheet taping to the rotor coil, which has excellent creep characteristics, and reduces the frictional resistance between the rotor coil and the insulating block. An object of the present invention is to provide a rotor for a rotating electric machine that has high reliability by preventing plastic deformation of the rotor coil by reducing thermal stress generated inside the rotor coil.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The rotor of a rotating electric machine according to the present invention will be explained below according to an embodiment shown in FIG. In FIG. 2, the same parts as in FIG. 1 are given the same reference numerals, and their explanations will be omitted.

That is, in this embodiment, between the rotor coil 13 and the insulating block 19, one surface of an aramid sheet (trade name: Nomex, manufactured by DuPont) that is in contact with the rotor coil 13 is coated with polyamide as shown in FIG. Tetrafluoroethylene spray powder (trade name: Yunon S, manufactured by Nippon Valqua Co., Ltd.) 21 was sprayed on it, and the other side was bonded to the insulating block 19.

According to the embodiment with the above configuration, the rotor coil 13
Between the rotor coil 13 and the insulating block 19, there is interposed a member made of an aramid sheet 20 whose coefficient of friction does not increase not only at low temperatures but also at high temperatures and on which polytetrafluoroethylene spray powder 21 is sprayed. The frictional restraint force on 19 is small. Therefore, the rotor coil 13
The internal thermal stress is also small and does not exceed the proof stress of the rotor coil 13. Since the polytetrafluoroethylene spray powder 21 penetrates between the paper-made fibers of the aramid sheet 20 and sticks thereto, the powder does not dissipate due to the sliding of the rotor coil 13, and its sliding effect is permanent. be. This combination of aramid sheet and polytetrafluoroethylene spray powder does not undergo plastic deformation even when subjected to thermal cycles, so rotor coil 1
The turn separator 15 in contact with the rotor 3 is not affected by the plastic deformation of the rotor coil 13, and the rotor 11 is not impaired in its function, thus increasing its reliability. In addition, in the case of conventional Nomex sheet taping, the rotor coil 13
Although the tape moves in the rotor axial direction due to the heating and cooling cycle, there is no such fear in the case of sheet pasting in this embodiment. Especially insulation block 1
It is particularly advantageous if 9 is of divided construction. Furthermore, spray powder 21 is applied to the sheet 20.
The intervening part of the member sprayed with is the insulation block 1.
9, the space factor of the rotor coil 13 in the uppermost turn is improved. In addition, in a hydrogen-cooled rotor, etc., the ventilation holes are not blocked. Furthermore,
It is easier to attach the member sprayed with the spray powder 21 to the sheet 20 of this embodiment than to tape the conventional Nomex sheet.
The sheet can be reliably interposed between the rotor coil 13 and the insulating block 19.

Further, as is well known, the aramid sheet 20 is made of heat-resistant polymer fibers that are rolled after being made into paper, and has extremely excellent creep resistance, so that there is almost no creep even when it is applied to a large, high-speed rotating machine.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a main part of a rotor of a conventional rotating electric machine, Fig. 2 is a sectional view of a main part of a rotor of a rotary electric machine according to an embodiment of the present invention, and Fig. 3 is a sectional view of a main part of the rotor of the above embodiment. It is. 12... Lotus slot, 13... Rotor coil,
18... Rotor wedge, 19... Insulating block, 20... Aramid sheet, 21... Polytetrafluoroethylene powder.

Claims (1)

[Scope of utility model registration request] A rotor coil and an insulating block for insulating the rotor coil from the ground are sequentially housed in a rotor slot, and the rotor coil is supported by a rotor wedge provided outside the rotor coil against the centrifugal force generated during rotation. 1. A rotor for a rotating electrical machine, characterized in that an aramid sheet made by spraying polytetrafluoroethylene powder on one surface is attached to a surface of the insulating block that is in contact with the rotor coil.