JP3928228B2 - Turbo blower - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a centrifugal turbo blower used for a gas circulator for a laser oscillator or the like.
[0002]
[Prior art]
Conventionally, in a centrifugal turbo blower used for a gas circulator for a laser oscillator or the like, a rolling bearing such as an angular bearing is adopted as a bearing for supporting the rotating shaft. Since this type of turbo blower is rotated in a high rotational speed range of several tens of thousands of revolutions / min by an electric motor as a rotor blade drive source, such a rolling bearing is configured to continue to supply lubricant such as oil. ing. On the other hand, in order to prevent this lubricating oil from reaching the rotor blades via the rotating shaft and mixing into the gas circulation path, the pressure in the bearing holding chamber is made lower than the pressure in the gas circulation path and is sealed in the middle of the rotating shaft. We are taking measures such as providing members.
[0003]
[Problems to be solved by the invention]
However, the slight leakage of the lubricating oil from the sealing member and the leakage due to the deterioration of the sealing member cannot be completely prevented, and some lubricating oil may be mixed into the gas circulation path due to aging. This causes problems such as oil adhering to the surface of the optical mirror in the laser oscillator, resulting in a decrease in the laser output value.
[0004]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention comprises a rotary blade, a rotary shaft fixed to the rotary blade, and a bearing that rotatably supports the rotary shaft. In a turbo blower that circulates gas in a gas circulation path by rotation, a dynamic pressure gas bearing that supports the rotating shaft in a non-contact manner by continuously supplying gas is used for the bearing, and the gas circulation path is provided in the dynamic pressure gas bearing. The cylinder is configured to supply and use the same gas as the circulating gas, and further includes a bearing holding chamber that holds the bearing, and a cylinder that supplies the bearing holding chamber with the gas circulating in the gas circulation path. The same gas as that circulated in the gas circulation path is introduced from the connected external port, and the gas pressure in the bearing holding chamber is held higher than the gas pressure in the gas circulation path. It is.
[0005]
In such a case, since no lubricating oil is used in the first place, the lubricating oil does not enter the gas circulation path, and the oil adheres to the optical mirror surface in the laser oscillator and the laser output value decreases. Can be drastically solved. Further, since the gas supplied to the dynamic pressure gas bearing is the same as the gas circulating in the gas circulation path, there is no problem even if the gas supplied to the dynamic pressure gas bearing is mixed into the gas circulation path. Accordingly, it is possible to eliminate a sealing material that has been necessary in the past, or to use a material having poor sealing performance. As a result, the rotating shaft can be brought into a completely non-contact state during rotation, which not only extends the product life but also reduces the frequency of maintenance.
[0006]
Also, a bearing holding chamber for holding the dynamic pressure gas bearing is provided, and the same as that circulated in the gas circulation path from an external port connected to a cylinder for supplying gas circulating in the gas circulation path to the bearing holding chamber. Since the gas is introduced and the gas pressure in the bearing holding chamber is held higher than the gas pressure in the gas circulation path, the heat generated in the dynamic pressure gas bearing is not provided with a cooling mechanism such as a water cooling mechanism. In both cases, the gas supplied to the dynamic pressure gas bearing can simultaneously diverge and cool, and the pressure of the gas film can be easily increased, and the bearing performance can be effectively improved by increasing the support force of the dynamic pressure gas bearing. You can also.
[0007]
【Example】
An embodiment of the present invention will be described below with reference to FIGS.
As shown in FIG. 1, a turbo blower 100 according to this embodiment includes a casing 5, a rotating blade 1, a rotating shaft 2 fixed to the rotating blade 1, and a bearing that rotatably supports the rotating shaft 2, This is a centrifugal type that includes an electric motor 4 that rotates the rotating shaft 2, and the one of this embodiment is used with the rotating blades 1 being raised.
[0008]
The casing 5 includes a gas compression chamber 51 that holds the rotary blade 1 and a bearing holding chamber 52 that is provided continuously below the gas compression chamber 51 and in which the rotary shaft 2 is loosely fitted. The gas compression chamber 51 includes a gas introduction port 53 that opens above the rotor blade 1 and a gas outlet port 54 that opens to the side of the rotor blade 1. The bearing holding chamber 52 is provided with a motor arrangement portion 55 in which an electric motor 4 described later can be arranged in the vicinity of the center thereof, and a thrust bearing arrangement portion 56 in which a thrust bearing 32 described later is arranged in the vicinity of the lower end thereof. ing. Furthermore, an external connection path 6 extends from the lower end and communicates with an external port 7 that opens to the outer surface of the casing. Further, the bearing holding chamber 52 and the gas compression chamber 51 are separated by, for example, a seal mechanism 8 provided around the upper end of the rotary shaft 2. The seal mechanism 8 does not completely separate the bearing holding chamber 52 and the gas compression chamber 51, but has a narrowing function and a communication function with a slight gap.
[0009]
The rotary blade 1 is generally known in which a plurality of blade bodies 12 are installed in a spiral shape on a slope portion of a truncated conical base body 11. The rotary shaft 2 is fixed to the bottom of the rotary blade 1, and a disc body 21 is integrally fixed in the vicinity of the end.
The bearing is called a dynamic pressure gas bearing. In this embodiment, the journal bearing 31 that supports the rotary shaft 2 with respect to a load acting in the journal direction, and the rotary shaft with respect to a load acting in the thrust direction. 2 and a thrust bearing 32 that supports 2. The journal bearing 31 is disposed at two locations from above and below the rotary shaft 2, for example, formed by rounding a rectangular thin plate and supporting one end thereof on the inner wall surface of the bearing holding chamber 52, A journal support plate 33 disposed around the rotary shaft 2 and a plurality of plates that are provided around the journal support plate 33 and elastically urge the journal support plate 33 inward to press the rotary shaft 2. A spring material 34 is used. The thrust bearings 32 are, for example, thrust support plates 36 respectively disposed above and below the disk body 21 and elastically energizing the thrust support plates 36 disposed above and below these thrust support plates 36 to press against the disk body 21. It is comprised from the leaf | plate spring material 37 to be made. When the rotating shaft 2 is stationary or below a certain number of rotations, the rotating shaft 2 is supported by the elastic biasing force, and when the number of rotations exceeds the certain number of rotations, the gas caught by the rotation of the rotating shaft 2 is used. Then, dynamic pressure is generated around the rotary shaft 2 and on the upper and lower surfaces of the disk body 21, and the journal support plate 33 and the thrust support plate 36 are moved backward by this dynamic pressure to form a gas film, and the rotary shaft 2 is not contacted. It has the function to support.
[0010]
The electric motor 4 is, for example, a DC brushless type in which a rotor 41 is externally fitted and fixed to the rotary shaft 2 and a stator 42 is disposed around the rotor 41 and supported by a casing 5. And the rotary shaft 2 is directly driven. In this embodiment, an inverter 43 is used as a drive source for the electric motor 4.
[0011]
The turbo blower 100 configured in this manner operates to suck the gas from the gas introduction port 53 and pressurize the gas from the gas outlet port 54 by rotating the rotor blade 1 with the electric motor 4. At that time, the same gas as the above gas is introduced into the bearing holding chamber 52 and supplied to the dynamic pressure gas bearings 31 and 32.
[0012]
Specifically, a method of supplying gas to the dynamic pressure gas bearings 31 and 32 will be described below by taking a case where a gas circulator for a laser oscillator is configured using such a turbo blower 100 as an example.
As shown in FIG. 2, the gas circulator for a laser oscillator according to this application example includes a gas circulation path RT, a laser oscillation part LR provided on the gas circulation path RT, and a gas circulation path RT in series with the laser oscillation part LR. A turbo blower 100 provided above, a heat exchanger RD provided downstream of the turbo blower 100, a mixed gas cylinder B for supplying gas circulating in the gas circulation path RT, and a vacuum pump P are configured.
[0013]
In this application example, the mixed gas cylinder B is connected to the upstream side of the turbo blower 100 in the gas circulation path RT through the on-off valve V1, and is connected to the external port 7 of the turbo blower 100 through the on-off valve V2. Moreover, the vacuum pump P is connected to the heat exchanger RD downstream side of the gas circulation path RT through the on-off valve V3.
When the turbo blower 100 is operated, the gas circulation path RT is first filled with a use gas to a predetermined pressure. For this purpose, the on-off valve V3 is opened and evacuated by the vacuum pump P, and then the on-off valve V3 is closed. Thereafter, the on-off valve V1 is opened to introduce gas from the mixed gas cylinder B into the gas circulation path RT. When the pressure reaches a predetermined pressure, the on-off valve V1 is closed. In practice, this operation is repeated several times to increase the gas purity to a predetermined level or higher.
[0014]
Next, the on-off valve V2 is slightly opened, and gas is supplied from the mixed gas cylinder B to the bearing holding chamber 52, that is, the dynamic pressure gas bearings 31 and 32 via the external connection path 6. This gas further leaks from the seal mechanism 8 and is supplied to the gas circulation path RT. This gas flow is indicated by an arrow x1 in FIG. On the other hand, the opening of the on-off valve V3 is adjusted so that the amount of gas corresponding to the amount obtained by subtracting the amount of gas consumed in the laser oscillator LR from this supply amount is discharged from the vacuum pump P, so Keep the gas amount constant. As a result, the gas flows in from the external port 7 and flows out of the seal mechanism 8 through the bearing holding chamber 52, and the gas in the bearing holding chamber 52 always flows. In this state, the gas pressure in the bearing holding chamber 52 is held higher than the gas pressure in the gas circulation path RT. Thereafter, the turbo blower 100 is operated, and the gas is circulated in the gas circulation path RT.
[0015]
Accordingly, in such a case, since no lubricating oil is used in the first place, the lubricating oil is not mixed into the gas circulation path RT, and the oil adheres to the surface of the optical mirror (not shown) in the laser oscillation unit LR and the laser output. The problem that the value decreases can be drastically solved. In addition, since gas flows into and out of the bearing holding chamber 52, not only gas is supplied to the dynamic pressure gas bearings 31 and 32 but also heat generated in the dynamic pressure gas bearings 31 and 32, or generated by the electric motor 4. Heat can be dissipated at the same time, and a heat-dissipating mechanism such as a water-cooling mechanism that has been conventionally required for cooling the electric motor 4 can be eliminated. Furthermore, since the amount of gas consumed in the laser oscillation unit LR can be supplemented at the same time, piping can be simplified such that a gas path for supply can be omitted.
[0016]
Furthermore, since the bearing holding chamber 52 is set to a high pressure, the pressure of the gas film can be easily increased, and the bearing performance can be effectively enhanced by increasing the supporting force of the dynamic pressure gas bearings 31 and 32.
[0017]
In addition, this invention is not limited only to the Example shown above. For example, another external port of the turbo blower may be provided, and the same kind of gas may be circulated in the bearing holding chamber independently of the gas circulation path. Further, the dynamic pressure gas bearing is not limited to the one in this embodiment, and other types can be applied. Further, the configuration of the gas circulator for the laser oscillator is not limited to that described in the application example. Various modifications can be made without departing from the spirit of the present invention, for example, the arrangement position of the vacuum pump and the mixed gas cylinder may be appropriately changed.
[0018]
【The invention's effect】
As described above, according to the present invention, the dynamic pressure gas bearing that supports the rotating shaft in a non-contact manner is used for the bearing, and the same kind of gas as the gas circulating in the gas circulation path is supplied to the dynamic pressure gas bearing. Therefore, it is possible to drastically solve the problem that oil adheres to the surface of the optical mirror in the laser oscillator and the laser output value decreases. Further, since the gas supplied to the dynamic pressure gas bearing is the same as the gas circulating in the gas circulation path, there is no problem even if the gas supplied to the dynamic pressure gas bearing is mixed into the gas circulation path. Accordingly, it is possible to eliminate a sealing material that has been necessary in the past, or to use a material having poor sealing performance. As a result, the rotating shaft can be brought into a completely non-contact state during rotation, which not only extends the product life but also reduces the frequency of maintenance. In addition, a bearing holding chamber for holding the dynamic pressure gas bearing is provided, and this is the same as that which is circulated in the gas circulation path from an external port connected to a cylinder for supplying gas circulating in the gas circulation path to the bearing holding chamber. In order to maintain the gas pressure in the bearing holding chamber higher than the gas pressure in the gas circulation path, a cooling mechanism such as a water cooling mechanism is provided for the heat generated in the dynamic pressure gas bearing. At the same time, the gas supplied to the dynamic pressure gas bearing can diverge and cool at the same time, the pressure of the gas film can be increased easily, and the bearing performance is also effectively improved by increasing the support force of the dynamic pressure gas bearing. You can also.
[Brief description of the drawings]
FIG. 1 is an overall schematic diagram showing an embodiment of the present invention.
FIG. 2 is a schematic circuit diagram showing an application example to which the turbo blower of the embodiment is applied.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Rotary blade 2 ... Rotating shaft 31 ... Bearing (journal bearing)
32 ... Bearing (Thrust bearing)

Claims (1)

In a turbo blower comprising a rotating blade, a rotating shaft fixed to the rotating blade, and a bearing that rotatably supports the rotating shaft, and circulating gas through a gas circulation path by rotating the rotating blade, A dynamic pressure gas bearing that supports the rotating shaft in a non-contact manner by continuously supplying gas is used for the bearing, and the same gas as the gas circulating in the gas circulation path is supplied to the dynamic pressure gas bearing for use. Further, a bearing holding chamber for holding a bearing is provided, and the same as that which is circulated in the gas circulation path from an external port connected to a cylinder that supplies gas circulating in the gas circulation path to the bearing holding chamber. A turbo blower characterized in that the gas in the bearing holding chamber is held at a pressure higher than the gas pressure in the gas circulation path.

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