JP4576746B2 - Turbo rotating equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a turbo-type rotating device such as a turbo-type vacuum pump, a turbo blower, a gas turbine, or a compressor that employs a turbo mechanism.
[0002]
[Prior art]
One type of turbo-type rotary device is a turbo-type dry pump that operates without bringing oil into a housing and is used in applications that require an oil-free environment. This dry pump is a multi-stage circumferential flow pump in which a rotor is axially mounted in a cylindrical housing via a bearing and performs pumping action of gas compression between the rotor and a stator formed on the inner periphery of the housing. The gas from the intake port on one end side in the axial direction of the housing is compressed and discharged to the exhaust port on the other end side in the axial direction of the housing. This circumferential flow pump is a non-contact type and belongs to the turbo type pump. Moreover, this turbo dry pump can be evacuated from the atmospheric pressure state and can create a vacuum region.
For such dry pumps, mechanical ball bearings, magnetic bearings, or hydrostatic bearings have been used as bearings, but recently they are convenient for maintenance, have a long service life, and reduce initial and running costs. Dynamic pressure gas bearings have been proposed.
[0003]
Examples of the dynamic pressure gas bearing include a foil bearing using a thin piece, that is, a foil, a tilting pad bearing using a tilting pad, and a spiral bearing using a spiral system. For example, in the case of a foil bearing, the foil is installed in a cantilever manner while the supporting surface to be supported and the surface of the rotating body to be supported are close to each other, and the foil forms a wedge-shaped gap that gradually narrows in the rotational direction. . A gas (gas) is entrained in the wedge-shaped gap to generate dynamic pressure, and the rotating body is supported on the base surface. Therefore, oil is not used like a ball bearing, and a completely oil-free environment (dry) is realized.
[0004]
[Problems to be solved by the invention]
Since the dynamic pressure gas bearing generates an air flow by the rotation of the rotating body and generates a dynamic pressure, heat is generated by friction of the air flow. The heat generation causes deformation of the equipment, and also looseness, resulting in noise and deterioration of the circumferential pump function. For this reason, cooling is usually performed by circulating a cooling gas through the bearing portion. An inert gas such as nitrogen gas is used as the cooling gas.
[0005]
By the way, since the bearing portion is non-contact, there is a pressure loss in the cooling gas flow path, and it is necessary to supply high-pressure cooling gas in consideration of this point. On the other hand, during operation of the turbo dry pump, the inside of the turbo dry pump becomes low pressure, the pressing force in the axial direction of the pump increases, and the bearing loss in the thrust bearing portion increases. Therefore, since the temperature of the dynamic pressure gas bearing portion is increased, it is necessary to supply a large amount of cooling gas at a high pressure. That is, a high pressure gas source is required. The running cost increases due to the high pressure gas supply. In addition, an increase in bearing loss requires an electric motor as a drive source for the rotating body, leading to an increase in size of a high-frequency motor / inverter, for example. This also increases costs. In addition, since this type of dry pump has a narrow gas flow path in the pump, a large flow rate of cooling gas is required, so it is necessary to pressurize and supply the gas in consideration of pressure loss. And increased costs.
The present invention is intended to provide a turbo rotating device that solves such problems.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, a turbo rotating device provided by the present invention is configured such that a rotating body is axially mounted in a cylindrical housing via a thrust dynamic pressure gas bearing, and a circumferential portion of the rotating body and the housing A turbo mechanism that performs gas compression with a stator formed on the inner periphery of the rotor is provided in multiple stages in the axial direction of the rotating body, and compresses gas from the inlet on one end side in the axial direction of the housing to A turbo-type rotary device that discharges to an exhaust port on the end side, and is a motion interposed between a disk in which the thrust dynamic pressure gas bearing is attached to the rotating body and the housing that faces the disk. In a rotary device that is configured by a pressure gas bearing member and provided with a cooling gas supply system that supplies cooling gas to the thrust dynamic pressure gas bearing, the cooling gas is caused to flow on the disk surface of the disk It is obtained by attaching a. Therefore, the rotation of the blades causes a flow in the cooling gas, and the dynamic pressure gas bearing portion is effectively cooled. The cooling gas may not be high pressure.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a turbo rotating device according to the present invention will be described with reference to embodiments shown in the drawings.
The drawing shows an example in which the turbo type rotating device provided by the present invention is implemented in a turbo type dry pump, and FIG. 1 is a diagram showing the basic configuration of the turbo type dry pump DP. As shown.
[0008]
The main body of the dry pump DP is composed of a cylindrical housing 1 and a rotating body (hereinafter referred to as a rotor) 2 that is rotatably supported by a bearing inside the housing 1. Specifically, the housing 1 has a bottomed shape as shown in the drawing, and an opening on one axial side (upper side) is an air inlet 1K, and an exhaust port on the other axial side (lower side) is in the middle. 1H is installed. A circumferential flow pump SP is constituted by a combination of the circumferential portion of the rotor 2 and the stator formed on the inner periphery of the housing 1. The circumferential flow pump SP is provided in a plurality of stages in the axial direction of the rotor 2, that is, in multiple stages. In addition, in the Example shown by FIG. 1, the example of what is called a hybrid type dry pump by which the thread groove pump was installed above the circumferential flow pump SP is shown.
[0009]
In the following, this configuration will be described in detail. First, a thread groove 1M is formed on the upper inner circumference of the housing 1, and the upper cylindrical portion 2P of the rotor 2 is opposed to the thread groove 1M. The combination of the thread groove 1M and the cylindrical portion 2P of the rotor 2 constitutes a so-called thread groove pump mechanism NP, which compresses molecules in the viscous flow region of gas by the rotation of the rotor 2 and pumps them downward.
[0010]
Furthermore, a stator portion 1T is stacked in the middle of the inner periphery of the housing 1 in multiple stages, specifically, seven stages in the axial direction. On the other hand, the rotor 2 is provided with a rotor circumferential portion 2 </ b> B that is inserted between the stators 1 </ b> T downward from the middle stage thereof. A groove 1G is formed at the inner peripheral end of the stator portion 1T, and a groove 2G is also formed at the outer peripheral end of the rotor circumferential portion 2B. An air flow is generated by the relative displacement of both the grooves 1G and 2G, and the pump function is activated. This pump function is sequentially connected to the subsequent stage through the flow path 1N, and gas compression is performed as a whole. Of course, the two are non-contact, but the circumferential flow pump SP is formed by the combination thereof. By the operation of the multistage circumferential flow pump SP, the gas pumped by the thread groove pump mechanism NP is further compressed and pumped downward, and exhausted to the exhaust port 1H through the exhaust passage 1R. That is, the circumferential flow pump SP at each stage compresses the gas at its circumference, sends the gas to the circumferential flow pump SP at the next stage through the flow path 1N at the end, and exhausts the gas by sequentially performing each stage. It is going.
[0011]
The above is the basic principle and operation of the turbo-type k dry pump DP. As shown in the drawing, the rotor 2 has an H-shaped cross section, and its central part is connected to the rotary drive mechanism and is attached to the shaft. Has been. That is, 3 is a rotational drive shaft and is disposed on the axis of the housing 1. The rotary drive shaft 3 is provided with a disk or flange portion 3F for bearings in the middle, and an electric motor (motor) 4 is integrally installed therebelow. This electric motor 4 is constituted by a combination of an armature winding 4M installed on the inner periphery of the housing 1 corresponding to the armature and a rotor winding 3M installed on the rotary drive shaft 3 corresponding to the rotor. The rotary drive shaft 3 is rotated at a high speed by the supply of electrical energy 9 from. In the figure, reference numeral 3S denotes a screw portion at the upper end of the rotary drive shaft 3 which cooperates with the nut 3N to fix the rotor 2 to the rotary drive shaft 3.
[0012]
Such a rotating body, that is, the rotor 2 is pivotally attached to the housing 1 by a bearing mechanism including a dynamic pressure gas bearing. That is, the illustrated dynamic pressure gas bearing is a foil bearing, and more specifically, a plurality of foil bearings 5 as thrust bearings are installed evenly around the vertical gap between the flange portion 3F and the cylindrical portion 1E of the housing 1. Yes. By being installed above and below the flange portion 3F, it is possible to cope with a strong thrust force. On the other hand, radial foil bearings 6 are installed above and below the rotary drive shaft 3 in two steps, upper and lower, in the gap with the cylindrical portion 1E of the housing 1. The rotor 2 is smoothly and non-contactedly supported by the foil bearings 5 and 6. Such a dynamic pressure gas bearing is a non-contact type bearing, but since heat is generated by a gas flow, this heat must be removed. Therefore, a cooling gas supply port 1F is provided as shown in FIG. 1, and the foil bearings 5 and 6 are cooled by the cooling gas supplied therefrom.
[0013]
The above configuration is a configuration of a conventional turbo-type dry pump. In these configurations, the present invention actively flows cooling gas for cooling the foil bearings 5 and 6 to the foil bearing portion. Means are provided.
That is, in the turbo type dry pump provided by the present invention, the disk is provided between the disk portion, specifically, the flange portion 3F with the foil bearing attached to the rotary drive shaft 3, and the housing 1 facing the flange portion 3F. A member for a dynamic pressure gas bearing, specifically, a foil is used, and a blade B is attached to the surface of the flange portion 3F opposite to the foil.
[0014]
FIG. 2 is an enlarged view of this configuration, and FIG. 3 is a bottom view of the flange portion 3F as viewed from below. As is apparent from these drawings, a plurality of blades B are radially attached to the bottom surface of the flange portion. Therefore, when the flange portion 3F is rotated at a high speed, the blade B also rotates at the same time to exhibit the function of the centrifugal pump, and a positive flow is generated in the cooling gas flowing in along the rotary drive shaft 3 from below. It will be.
[0015]
2 and 3, the blade B is attached only to the lower surface of the flange portion 3F. However, this blade B generates an air flow in the outer circumferential direction over the entire area of the lower surface of the flange portion 3F. It is. Along with this air flow or being urged by this air flow, the cooling gas actively flows to the upper surface side of the flange portion 3F, and the member (foil) of the foil bearing 5 is efficiently cooled.
[0016]
FIG. 4 to FIG. 7 show the embodiments in which the attachment position and the number of attachments of the blades B are changed. In addition, these embodiments are examples in which the members of the foil bearings 5 are interposed on the both disk surfaces of the flange portion 3F. First, in the case of FIG. 4, the function of the centrifugal pump greatly acts in an example in which the blade B is provided near the outer periphery of the flange portion 3F.
[0017]
In the embodiment of FIG. 4, the blade B has a spiral shape as shown in FIG. 5, and the flange portion 3F, that is, the rotary drive shaft 3 is rotationally driven in the direction of the arrow. By the rotation in the direction of the arrow, an air flow is generated on the upper surface of the flange portion 3F from the outer circumference toward the inner side, and the cooling gas from below flows upward to cool the members of the upper and lower foil bearings 5. Become.
Next, FIG. 6 shows an example in which the blade B shown in FIG. 4 is moved inward of the flange portion 3F. Of course, in this case as well, the blades B are attached in a spiral shape as in the case shown in FIG. 5, and an air flow is generated from the outside to the inside by rotation.
FIG. 7 shows an example in which blades B are provided on both upper and lower surfaces of the flange portion 3F. In addition, the blade B is attached near the outer periphery of the flange portion 3F. In this case, the shape of the blade B is radial as in the case shown in FIG. 3, and the centrifugal pump function is caused. Therefore, the air on both the upper and lower surfaces of the flange portion 3 </ b> F flows to the outer periphery and is formed in the housing 1. Cooling gas or the like is discharged to the discharge port 1Q. This discharge causes a flow in the cooling gas from below, so that the foil member of the foil bearing 5 is efficiently cooled by the cooling gas. Moreover, although the gas from the upper surface of the flange part 3F contains a cooling gas, it is necessary to prevent this cooling gas from flowing upwards by a vacuum pump. Therefore, it is possible to prevent the cooling gas from flowing to the vacuum pump side due to the occurrence of the air flow by the blade B.
FIG. 8 shows an example in which the blade B is attached to both surfaces of the flange portion 3F and inside the flange portion 3F. Although it is attached inward, the shape is radial as in FIG. 3 and has a function of urging the gas inward outward. Accordingly, the lower cooling gas flows outward and actively cools the foil bearing 5.
In FIGS. 9 and 10, the flange portion 3F is increased in thickness, a hole is formed in the thickness, and a blade 3B is further formed in the hole, and the cooling gas is positively passed through the hole. This is an example of flowing.
FIG. 9 is a view in which a flange 3F is connected to a longitudinal hole TA drilled in the base portion protruding from the rotary drive shaft 3 and a hole HA drilled in the radial direction, and a blade 3B is formed inside. . Therefore, the blade 3B causes a centrifugal pump action by the rotation of the flange portion 3F, and the cooling gas below is actively flowed through the holes TA and HA as shown by the arrows to cool the foil bearing 5 and the like. It will be.
In FIG. 10, a vertical hole ZA is formed in the central portion of the rotary drive shaft 3, and this is connected to a radial hole HA. Reference numeral 3B denotes a blade. In this embodiment, the same function as that shown in FIG.
[0018]
The turbo rotating device provided by the present invention is as described in detail above, but is not limited to the above and illustrated examples, and various modifications can be given.
First, an example of a turbo-type dry pump is shown as a turbo-type rotary device, but the present invention can also be applied to a turbo-molecular pump. Furthermore, it can be effectively applied not only to vacuum pumps but also to turbo blowers, turbo gas turbines, and turbo compressors.
Next, regarding the configuration of the invention, the dynamic pressure gas bearing is not limited to a foil bearing, and the present invention can also be applied to a thrust dynamic pressure gas bearing employing a bearing such as a tilting pad bearing. .
Further, the shape, number, and location of the blades attached to the flange portion (disk) are not limited to the above and illustrated examples. FIGS. 9 and 10 show an example in which a hole as a passage is formed in the flange portion. However, the flange portion is formed into two pieces and joined together with a gap, and a blade is interposed in the gap. Examples of such modifications are also included.
The present invention includes all of them.
[0019]
【The invention's effect】
Since the present invention is as described above in detail, the supply of the cooling gas to the thrust dynamic pressure gas bearing is efficiently performed with a simple configuration, which can improve the durability of the turbo rotating device. it can. In particular, the cooling gas source can be reduced in pressure (normal pressure). Accordingly, the required power of the apparatus can be reduced, and the entire rotating device can be made compact.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a turbo dry pump embodying the present invention.
FIG. 2 is an enlarged view showing a configuration of a main part of the present invention.
3 is a bottom view showing the configuration of FIG. 2 from below. FIG.
FIG. 4 is an enlarged view showing a configuration of another embodiment of the present invention.
5 is a plan view showing the main part of the configuration of FIG. 4 from above. FIG.
FIG. 6 is an enlarged view showing a configuration of another embodiment of the present invention.
FIG. 7 is an enlarged view showing a configuration of another embodiment of the present invention.
FIG. 8 is an enlarged view showing a configuration of another embodiment of the present invention.
FIG. 9 is an enlarged view showing a configuration of another embodiment of the present invention.
FIG. 10 is an enlarged view showing a configuration of another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Housing 2 ... Rotating body 3 ... Rotary drive shaft 3F ... Flange part 4 ... Motor 5, 6 ... Foil bearing 1F ... Supply port 1Z, 1Q ... Discharge port NP ... Screw groove pump SP ... Circumferential flow pump B, 3B ... Wings

Claims (5)

A turbo mechanism that has a rotating body axially attached to a cylindrical housing via a thrust dynamic pressure gas bearing and performs a gas compression action between a circumferential portion of the rotating body and a stator formed on the inner periphery of the housing. A turbo-type rotary device that is provided in multiple stages in the axial direction of the rotating body, compresses the gas from the intake port on one end side in the axial direction of the housing, and discharges it to the exhaust port on the other end side in the axial direction of the housing, The thrust dynamic pressure gas bearing is constituted by a disk provided on the rotating body, and a dynamic pressure gas bearing member interposed between the disk and the housing opposed to the disk, and the thrust dynamic pressure gas bearing is cooled to the thrust dynamic pressure gas bearing. A turbo rotating device provided with a cooling gas supply system for supplying gas, wherein a blade for flowing the cooling gas is attached to a disk surface of the disk. 2. The turbo rotary device according to claim 1, wherein a blade is attached to a disk surface on one side of the disk, and a dynamic pressure gas bearing member is interposed between the disk surface on the other side and the housing. A dynamic pressure gas bearing member is interposed between each disk surface of the disk and the housing, and a radial passage is provided inward of the disk. When the disk rotates, the outer periphery of the disk starts from the end of the disk at the center of the disk. 2. The turbo rotating device according to claim 1, wherein the cooling gas flows toward the end of the passage. 2. The turbo rotating device according to claim 1, wherein the wing is attached near the outer periphery of the disk. A member for a dynamic pressure gas bearing is interposed between each disk surface of the disk and the housing, each blade attached to both surfaces of the disk, and a discharge passage for discharging the cooling gas flowing by both blades out of the housing The turbo rotating device according to claim 1, wherein the turbo rotating device is provided.

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