JPH02168830A - Crow pole type synchronous generator - Google Patents

Abstract

PURPOSE:To stabilize a bearing and to improve cooling effect of rotor by making plural lines of static pressure supply holes for floating the rotor through a frame then arranging a ceramic bearing in the frame while furthermore providing a static pressure bearing and a cooling gas switching valve. CONSTITUTION:Cooling gas is ejected from a gas supply source 30 through a two-way switching valve 37, a gas supply hole 32, a groove 31 and a gas supply hole 30 made through the frames 13, 14 to the cylindrical face of a rotor 1. Then the switching valve 37 is switched and cooling gas is fed to a cooling gas supply hole 35 then it is discharged through a delivery hole 36.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Field of Application) The present invention relates to a claw-pole generator in which a turbine and a compressor are installed at both ends of a rotating shaft, and in particular to a claw-pole generator that is equipped with a turbine and a compressor at both ends of a rotating shaft. This invention relates to a claw-pole generator that has low starting torque, supports a rotating shaft system with high stability during high-speed rotation, is equipped with a low-loss gas bearing, and aims to improve cooling performance inside the generator.

(Prior Art) FIGS. 2 and 3 are a vertical cross-sectional view showing the principle structure of a conventional claw-pole generator, and a cross-sectional view taken along the line mm of the rotor in FIG. 2.

A rotor (1) of the generator is supported by rolling bearings (2) provided at both shaft ends and a bearing bracket (3).

The bearing bracket (3) is fixed to the stator frame (4), and a non-magnetic frame (4a) is placed in the center of the stator frame (4).
A stator core (6) is attached through the stator core (6), and an armature winding (5) is housed inside the stator core (6).

The rotor (1) of the claw pole generator is divided into two parts in the axial direction, and as shown in the cross section of the central part of the rotor (1) in Figure 3, each is magnetized to the N pole and S pole, and the non-magnetic material (7) It is made by butt welding. The rotor (1) of a generator having such a two-pole permanent magnet serves as a mechanically rigid rotating shaft and is suitable for an ultra-high speed rotating body.

On the other hand, the field winding (8) is housed within both ends of the stator frame (4) so as to form a magnetic path (9), and is excited by passing a direct current to supply power to the armature winding (5). occurs.

As described above, when a low-pole generator is employed in a Preyton cycle power generation system, a turbine and a compressor are mounted on the generator rotor shaft. For example, in the Preyton cycle power generation system used for space thermal power generation,
Active magnetic bearings or gas bearings are used as bearings because ultra-high speed rotation is required to reduce size and weight, and high efficiency and long-term reliability are required under these conditions.

FIG. 4 shows a vertical cross-sectional view of a low-pole synchronous generator of the Preyton cycle type using the existing gas bearing technology, which is generally known in the art.

Next, this configuration will be explained.

A turbine (1) and a compressor (12) are attached to both ends of the rotor (1) of the generator. Stator frame (
A stator core (6) is fitted into the stator core (6) through a non-magnetic frame (4a), and the armature winding (5) is housed inside the stator core (6). Field winding frames (13) and (14) are fixed to both end faces of the stator frame (4), and the field winding (8) is housed inside the field winding frames (13) and (14). A bearing housing (16) is attached to the end face of the field winding frame (13) on the turbine (11) side.
As shown in FIG. 5, which shows a cross section along the v-v line in FIG.
) and a fixing nut (19).
15) is installed around the circumference of the generator rotor (11). On the other hand, the end face of the field winding frame (14) on the compressor (12) side is equipped with a thrust bearing device consisting of a thrust 1 bearing (20), a spacing piece (21), and a thrust disk (22). . Further, on the compressor (12) side of the spacing piece (21), the same radial bearing device (15) shown in FIG. 5 as on the turbine (11,) side is installed.

Additionally, labyrinth seals (23) are provided between the turbine (11), the compressor (12), and each radial bearing device (15).
) is equipped. Further, a partition tube (24) is installed on the inner peripheral surface of the stator core (6) to prevent the cooling medium from escaping from the armature winding (5), field winding (8), etc.

(Problem to be solved by the invention) 14= Problems caused by such a conventional configuration are listed below.

(1) At the time of startup, no gas film is formed between the generator rotor (1) and the pad (17) of the radial bearing device (15), and there is a state of solid contact between the rotor (1) of the generator and the pad (17) of the radial bearing device (15). necessary, and the generator rotor (1) and pad (
17) Abrasion of the sliding surface becomes a problem.

(2) Generally bearing housing (16), pad (17)
) and the pivot 1-(18), etc., are made of magnetic material. In this case, the unnecessary magnetic path (9a) shown by the broken line other than the necessary magnetic path (9) of the generator shown in FIG.
20). Therefore, between the pad (17), the thrust I-bearing (20), and the rotor (1) of the generator, due to changes in magnetic attraction, rotational speed, shaft vibration, etc., changes in magnetic flux cause the bearing to rotate. or the bearing itself may cause unstable vibration.

(3) In the case shown in Fig. 4, which uses gas bearings, the rotor shaft length is long, and the turbine (11) and compressor (12) are installed at both ends of the shaft, so the critical speed of the generator rotor is reduced and the rated rotation speed is reduced. By the time you reach the end of the road, you will have to pass multiple dangerous speeds. In order to exceed such critical speeds, it is possible to increase the elastic force and damping force of the gas bearing, but this requires increasing the axial length of the gas bearing, which ultimately leads to higher-order resulting in dangerous speeds of

(4) In an ultra-high-speed rotating body, the loss in the rotor (1) and bearing portion of the generator becomes large, and the temperature of the rotor (1) portion of the generator becomes high with only natural convection.

The present invention was developed in view of the problems of the prior art described above, and it stabilizes the bearing by reducing the starting torque of the bearing, prevents wear, prevents the formation of a magnetic path in the bearing, and increases the critical speed of the generator. It is an object of the present invention to provide a claw-pole type cyclic generator that has a short rotor shaft length and has a comprehensive functional improvement in the cooling effect of the rotor of the generator.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, in the present invention, several static pressure air supply holes are provided in the field winding frame to provide a static pressure bearing function that floats the rotor of the generator. In addition, a non-magnetic ceramic bearing is installed in the field winding frame, and a switching valve is installed to roughly switch between the static pressure bearing and the cooling gas.

(Function) In this way, air is supplied from the static pressure air supply hole to float the generator rotor, so there is almost no sliding of the bearing pad with the generator rotor during startup, and in the unlikely event that sliding occurs. However, since the rotor is light and the bearings are made of ceramics, there is little risk of the sliding parts being worn out. Furthermore, at startup, the area around the opening of the static pressure supply hole acts as a bearing, so the support interval for the rotor becomes shorter, the critical speed becomes higher, and the degree of safety increases. Further, once the vehicle is in operation, a ceramic bearing is used, but since this bearing is disposed within the field winding frame, there is little reduction in critical speed. Since the supply of static pressure gas can be switched to the supply of cooling gas, the synchronous generator can be made smaller and lighter with high reliability and efficiency.

(Example) An example of the present invention will be described below with reference to FIG. It should be noted that some parts described in the conventional structure of FIGS. 2 to 5 are given the same reference numerals and the description thereof is omitted.

In FIG. 1, pads (25) are arranged by spherical pivots (26) on the inner peripheral surfaces of the field winding frames (13), (14) on the turbine (11) side and the compressor (12) side. This pad (25) is made of a non-magnetic ceramic material such as silicon nitride or silicon carbide, which is excellent as a bearing material. The thrust bearing (27) is also made of ceramic material.

The labyrinth seal (28) on the turbine (11) side is directly fixed to the field winding frame (13). Furthermore, the field winding frame (14) on the compressor (12) side has a thrust housing (2) that also has a labyrinth seal function.
9) is directly fixed.

Several static pressure air supply holes (30) are machined on the circumference of both field winding frames (13) and (14), and circumferential air supply grooves (31) are machined on the end faces. Furthermore, this air supply circumferential groove (3
A radial air supply hole (32) perpendicular to 1) is machined.

Further, "0" ring grooves (33) are machined on the end faces of the labyrinth seal (28) and the thrust housing (29), respectively, and accommodate the "0" rings (34).

Cooling air supply holes (35) are machined in the labyrinth seal (28). On the other hand, cooling discharge holes (36) are formed in the thrust housing (29). A 3-port, two-way switching valve (37) is installed on the outside of the generator body, and outlet 2
One of the ports is connected to two air supply holes (32), the other port is connected to a cooling air supply hole (35), and the inlet port is connected to a gas supply source (39) by respective air supply pipes (38). Note that several axial ventilation holes (40) are machined in the thrust disk (22).

Next, the effect will be explained.

The pressurized gas body is supplied to the turbine (11), and the rotor (1) of the generator is driven; however, at this time, the gas supply source (3
9) through the two-way switching valve (37) and the air supply hole (32).
through the air supply circumferential grooves (31) and static pressure air supply holes (30) provided in the field winding frames (13) and (14),
It is ejected onto the cylindrical surface of the generator rotor (1). In this state, the rotor (1) of the generator floats due to the supply gas pressure,
For this reason, the pad (25) and the rotor (1) of the generator are in a non-contact state, so the torque at startup is small, and
It is possible to prevent wear of the pad (25) and the rotor (1) of the generator at the time of startup. And static pressure supply hole (3
Since the area around the opening 0) acts as a bearing, the support interval for the generator rotor 1 becomes shorter, the critical speed becomes higher, and the degree of safety during startup becomes greater. In this state, the turbine (
11) Increase the gas supply to reach the rated rotation speed. Next, the field winding (8) is energized and the generator starts operating, but at this time, the static pressure air supply holes (30) provided in the field winding frames (13) and (14) have small hole diameters. Since the number of field windings (8) is small, there is no adverse effect on the magnetic path due to the field winding (8).

At the same time, the bat (25) is connected to the field winding frame (13),
(14), the structure of the radial bearing device is simplified compared to the conventional technology, and the axial length of the generator rotor (1) is shortened, which directly reduces the critical speed. influence and make driving easier. At this time, pad (2
5) is made of a non-magnetic ceramic material that is excellent as a bearing material.For this reason, the magnetic flux passing through the pad (25) and the rotor (1) of the generator decreases rapidly.
), and highly stable operation is possible.

When power generation operation begins, electrical and mechanical losses will naturally increase rapidly in the central part of the generator rotor (1), where the so-called armature winding (5) is located, but this static pressure supply Stomata (
30), the flow of the gas in the center is small and the temperature becomes high.

To prevent this, the two-way switching valve (36) is switched when power generation operation begins. That is, the supply to the air supply hole (32) is stopped 5, and the air is supplied to the cooling air supply hole (35). At this time, the effect of floating the generator rotor (1) is completely lost, but the para F (25) and the generator rotor (
1) A dynamic pressure film is formed by the interaction of the sliding surfaces,
The floating state of the rotor (1) of the generator can be sufficiently maintained.

The flow of gas for cooling flowed axially between the back of the Para F (+5) and between the pans divided into multiple pieces in the circumferential direction, cooling the central part of the generator rotor (1). Afterwards, pass around the pad (15) on the opposite side, and pass through the slus I to the disc (22).
) and the cooling discharge hole (36) of the slusl to the housing (29). The rotor (1) of the generator is sufficiently cooled by this cooling passage. This prevents thermal expansion in the radial direction of the generator rotor (1), maintains a stable bearing clearance between the pad (25) and the generator rotor (1), and maintains constant bearing characteristics. Make it possible to hold it.

[Effects of the Invention] As explained above, according to the present invention, a static pressure function for levitating the rotor of a generator in a field winding frame and a dynamic pressure generation pad made of a non-magnetic ceramic material are provided. Because it is installed, the axial length of the generator rotor is shortened,
The critical speed of the shaft system is increased, and the problem of unstable vibration of the bat due to the passage of magnetic flux can be solved.

Furthermore, by improving the cooling performance of the generator rotor, it becomes possible to maintain stable bearing characteristics.

Due to the combination of these effects, an ultra-high-speed claw pole with high efficiency, small size and light weight, and long-term reliability is achieved. Figure 1 is a vertical cross-sectional view of a claw pole type synchronous generator showing one embodiment of the present invention, and Figure 2 is a longitudinal cross-sectional view of a claw pole type synchronous generator showing an embodiment of the present invention. Figure 3 is a cross-sectional view of the main body of a conventional claw pole generator, Figure 3 is a cross-sectional view of the rotor in Figure 2 taken along line Hl-H, and Figure 4 is a prior art Prayton cycle type generator. FIG. 5 is a longitudinal cross-sectional view of the pole generator, and is a cross-sectional view taken along the line ■-■ of FIG. 4.

1. Generator rotor 4... Stator frame 15
...Field winding frame 25...Nonmagnetic pad 30
Static pressure air supply hole 35...Cooling air supply hole 37...
Switching valve agent Patent attorney Norio Oko

Claims (1)

[Claims] In a claw-pole synchronous generator using gas bearings, several static pressure air supply holes are provided in the field winding frame to supply gas that floats the generator rotor, and ceramics are provided in the field winding frame. A claw pole synchronous generator characterized by being equipped with a non-magnetic gas bearing pad made of wood and a switching valve that switches gas for the static pressure air supply hole and the cooling air supply hole.