JPH0828552A - Dynamic pressure bearing unit - Google Patents

Abstract

PURPOSE:To apply a radial load and a thrust load, exerted on a rotary shaft, during both reversing and forward rotation of the rotary shaft, to improve sealing performance of the interior of a bearing from using environment, and to hold working fluid in the bearing even during the stop of the rotary shaft. CONSTITUTION:A radial dynamic pressure bearing 3 and a pair of thrust dynamic pressure bearings 4 and 4 through which a rotary shaft 1 is supported on a housing 2 are provided. The radial dynamic pressure bearing 3 is nipped between the thrust dynamic pressure bearings 4 and 4 rotatable in forward and reverse directions and an inflow passage 21 to feed working fluid is communicated with a gas between the bearings of the radial dynamic pressure bearing 3, and the inflow passage 21 is opened and closed by a switching valve 22 according to the rotation direction of the rotary shaft 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic pressure bearing which supports a rotary shaft by utilizing the dynamic pressure of a fluid such as gas or liquid. For example, the rotation of the impeller shaft of an axial flow pump or a magnet pump. The present invention relates to a dynamic pressure bearing that can be used as a bearing for bearings.

[0002]

2. Description of the Related Art In a dynamic pressure bearing, a fluid dynamic pressure generated at the time of rotation of the shaft is used to support the rotary shaft, and in order to obtain a dynamic pressure sufficient to apply a load acting on the rotary shaft, A groove for dynamic pressure generation having a predetermined pattern is formed on the shaft or the bearing. Since this dynamic pressure generating groove has directionality,
The conventional dynamic pressure bearing can apply a load only by rotating the rotary shaft in one direction.

However, as thrust dynamic pressure bearings (hereinafter referred to as thrust bearings), there have already been proposed those capable of applying an axial force (thrust load) acting on the rotary shaft when the rotary shaft rotates in both forward and reverse directions (special feature). (Kaisho 62-20911, etc.). This thrust bearing has thrust plates having spiral grooves in opposite directions when viewed from the front and back sides, respectively, a fixed receiving plate facing one side of the thrust plate through a working fluid, and a rotary shaft. The thrust receiving plate and the rotation receiving plate are attached and are opposed to the other surface of the thrust plate through a working fluid, and the thrust plate and the rotation receiving plate are rotated regardless of whether the rotation shaft is rotated in the forward or reverse direction. Dynamic pressure is generated between the thrust plate and the fixed receiving plate.

That is, when the rotary shaft rotates in the forward direction, the working fluid between the thrust plate and the rotary receiving plate is moved to the center side by the action of the spiral groove, and the working fluid between the thrust plate and the rotary receiving plate is moved. A dynamic pressure is generated in the inner surface of the inner wall of the inner wall to form a lubricating film of the working fluid. Thus, the rotation receiving plate and the thrust plate can be held in a non-contact state while resisting the thrust load acting on the rotating shaft. On the other hand, the working fluid between the thrust plate and the fixed receiving plate is removed to the outer peripheral side by the action of the spiral groove, and a negative pressure is generated between the thrust plate and the fixed receiving plate. Is fixed by adsorption.

When the rotary shaft rotates in the opposite direction,
The working fluid between the thrust plate and the fixed receiving plate is moved toward the center by the action of the spiral groove, and a dynamic pressure is generated between the thrust plate and the fixed receiving plate to form a lubricating film of the working fluid. Therefore, the fixed receiving plate and the thrust plate can be held in a non-contact state. On the other hand, the working fluid between the thrust plate and the rotation receiving plate is removed to the outer peripheral side by the action of the spiral groove, and the thrust plate is attracted and fixed to the rotation receiving plate and rotates together with the rotation receiving plate.

Therefore, in the thrust bearing described in the publication, no matter which direction the rotary receiving plate rotates, a high-pressure fluid lubrication film is formed between the thrust plate and the rotary receiving plate or between the thrust plate and the fixed receiving plate. Is formed so that the thrust load acting on the rotary support plate can be applied with a minimum power loss.

[0007]

However, the thrust bearing disclosed in the above publication can only be loaded with a thrust load as its name implies, and must be loaded with a radial load acting perpendicularly to the rotating shaft. I couldn't. For this reason, when using the thrust bearing, it is necessary to separately provide a radial bearing for loading the radial load on the rotary shaft, and the structure for supporting the rotary shaft must be complicated. . Therefore, it has been desired to develop a dynamic pressure bearing capable of not only a thrust load but also a radial load with respect to the rotation of the rotary shaft in both the forward and reverse directions.

On the other hand, the thrust bearing disclosed in the above-mentioned JP-A-62-20911 is used for supporting the impeller shaft of an axial flow pump such as a vertical shaft pump, but the axial flow pump contains slurry such as muddy water. Since the pumped water covers the bearing, the bearing used for this purpose is required to have special performance such as sealing property against slurry. For such a request,
In the past, measures were taken to cover the thrust bearing with a casing that sealed the working fluid, or to use a material with high wear resistance for the thrust plate, but this caused problems such as an increase in size and cost of the device. It was

When the thrust bearing is used as an axial flow pump, pumping water can be used as the working fluid. When pumping water is used as the working fluid, pumping is stopped once the pump is stopped. Since the pump moves down in the pumping channel, pumping water, which is a working fluid, comes out of the bearing, and there is a problem that the thrust plate and the receiving plate come into solid contact when the pump is restarted. For this reason,
The thrust plate was damaged and the bearing life was shortened, and a large starting torque was required to restart the pump.

Further, in the thrust bearing, when the working fluid is air, if the rotating shaft is stopped and the thrust plate and the fixed receiving plate are kept in contact with each other for a long time, both of them are fixed due to dew condensation, A large torque is required for restarting the rotating shaft, and in extreme cases, even if the rotating shaft is restarted, the function as a bearing may not be exhibited.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a dynamic pressure bearing unit capable of applying a radial load and a thrust load in both forward and reverse rotations of a rotary shaft. To provide.

Another object of the present invention is to provide a dynamic pressure bearing unit which has a high hermeticity of the inside of the bearing against the use environment and which can hold a working fluid in the bearing even when the rotating shaft is stopped. To do.

Still another object of the present invention is to provide a hydrodynamic bearing unit which can always favorably support a rotating shaft even if the rotating shaft is repeatedly started or stopped.

[0014]

In order to achieve the above object, the dynamic pressure bearing unit of the present invention has a housing and a radial dynamic pressure that rotatably supports a rotary shaft passing through the housing with respect to the housing. The radial dynamic pressure bearing comprises a bearing and a pair of thrust dynamic pressure bearings. The radial dynamic pressure bearing has an inner ring and an outer ring facing each other with a predetermined bearing gap, and one of the inner ring and the outer ring is formed with a herringbone groove. The thrust dynamic pressure bearing has a fixed receiving plate, a rotary receiving plate, and thrust plates facing the receiving plates with a predetermined bearing gap, and the front and back surfaces of the thrust plate are opposite to each other when viewed from their respective surface sides. A spiral groove is formed in the opposite direction, and a pair of thrust plates are loosely fitted to the rotary shaft at both ends of the radial dynamic pressure bearing, and the bearing gap of each thrust dynamic pressure bearing is set to the bearing of the radial dynamic pressure bearing. And a switching valve for communicating with the space between the housing and an inflow passage for supplying a working fluid to the bearing gap of the radial dynamic pressure bearing in the housing, and for opening and closing the inflow passage according to the rotation direction of the rotary shaft. Is provided (Claim 1).

According to the present invention, as described in Japanese Patent Laid-Open No. 62-20911, spiral grooves are formed on the front and back surfaces of the thrust plate of the thrust dynamic pressure bearing in directions opposite to each other when viewed from the respective surface sides, and the thrust plate is formed. Since it is loosely fitted to the rotating shaft, when the rotating shaft rotates, the working fluid is urged toward the center on one side of the thrust plate, and the working fluid is urged toward the outer peripheral side on the other side. The gap between the plate and the rotary shaft functions as a circulation path for the working fluid. That is, no matter which direction the rotary shaft rotates, the working fluid sucked between the thrust plate and the receiving plate on one surface of the thrust plate will not pass through the gap between the thrust plate and the rotary shaft. The other surface of the thrust plate is discharged to the outer peripheral side of the thrust plate along the surface.

The dynamic pressure bearing unit of the present invention thus constructed may use either gas or liquid as its working fluid. When a liquid is used as the working fluid, a flat lid portion is formed on the outer peripheral side of the spiral groove formed on both front and back surfaces of the thrust plate,
In addition, it is preferable to form a circulation flow path through the thrust plate at the boundary between the spiral groove and the plane area (claim 2).

According to this structure, the working fluid interposed between the thrust plate and the receiving plate is sealed by the flat ridge portion formed on the outer peripheral side of the spiral groove, so that the working fluid is thrust. Does not leak from between the backing plate and the back plate. Further, since the working fluid sealed in the bearing by the lid portion flows into the circulation passage formed at the boundary between the spiral groove and the flat area, the dynamic pressure is applied from the side where the dynamic pressure is not generated across the thrust plate. The working fluid can be circulated to the side where

That is, in the structure according to the second aspect, the working fluid circulates from the side where the dynamic pressure is generated to the side where the dynamic pressure is not generated through the gap between the thrust plate and the rotary shaft as the thrust plate rotates. Further, it is possible to circulate through the circulation flow path from the side where the dynamic pressure is not generated to the side where the dynamic pressure is generated, and to prevent the leakage of the working fluid to the outside of the bearing.
Therefore, if the working fluid is filled between the front and back surfaces of the thrust plate and each receiving plate in advance, the working fluid circulates inside the thrust dynamic pressure bearing, so that, for example, the bearing around the bearing, such as the bearing of an axial flow pump. Even when is filled with the slurry, the slurry does not enter the gap between the thrust plate and the receiving plate. Further, since the bearing gap of the radial dynamic pressure bearing is connected to that of the thrust dynamic pressure bearing, the working fluid of the radial dynamic pressure bearing is not lost unless the working fluid leaks from the thrust dynamic pressure bearing.

Further, when the working fluid is circulated by itself, in addition to the structure described in claim 2, a supply passage for supplying the working fluid to the gap between the thrust plate and the receiving plate is formed in the fixed receiving plate, and It is preferable to provide an outflow prevention valve that closes this supply passage when the rotating shaft is stopped (claim 3). According to this configuration, even if the fluid leaks from the space between the thrust plate and the receiving plate to the outside of the bearing, the working fluid can be replenished from the supply passage, and the amount of the working fluid circulating by itself can be reduced. It is possible to reduce the risk of the solid contact between the thrust plate and the receiving plate due to the decrease.

Further, when the outflow prevention valve and the inflow passage switching valve are closed when the rotating shaft is stopped, the working fluid is thrust dynamic pressure bearing and radial dynamic pressure bearing even if the self-circulation action of the working fluid is lost. It is possible to prepare for restarting the rotating shaft while keeping the working fluid in each bearing gap without flowing out from the bearing gap.

In addition, when pumping water or pumping liquid is used as the working fluid like the bearing of a pump, even if the pump stops and the dynamic pressure bearing unit of the present invention is exposed from the pumping, the rotating shaft stops. If the above-mentioned outflow prevention valve and switching valve are closed during the operation, pumping water or pumping liquid can be retained in the bearing gap of the thrust dynamic bearing and radial dynamic pressure bearing, and when the pump is restarted Can be supported smoothly.

When gas is used as the working fluid, the outer peripheral edge of the thrust plate is formed thinner than its inner peripheral edge in order to prevent the thrust plate and the receiving plate from sticking to each other when the rotary shaft is stopped. Is preferred (Claim 4).

In the present invention, the inner ring or the outer ring of the radial dynamic pressure bearing may be formed integrally with the rotating shaft or the housing. Similarly, the fixed receiving plate or the rotating receiving plate of the thrust dynamic pressure bearing may be formed integrally with the rotating shaft or the housing.

[0024]

With the positive rotation of the rotary shaft, the herringbone-shaped groove in the radial dynamic pressure bearing urges the working fluid toward the axial center of the bearing gap. Therefore, a high dynamic pressure is generated at the axial center of the bearing gap. On the other hand, with the reverse rotation of the rotating shaft,
The herringbone groove urges the working fluid toward both axial ends of the bearing gap. In the present invention, the thrust dynamic pressure bearings are arranged at both ends of the radial bearing, and the bearing gap of the radial dynamic pressure bearing is not opened, so that the working fluid generates a high dynamic pressure at both axial ends of the bearing gap. A switching valve is provided in the inflow passage of the working fluid formed in the housing, and the switching valve is opened and closed according to the rotation direction of the rotary shaft. That is, in the forward rotation of the rotary shaft, the switching valve is closed in order to prevent the working fluid pressurized in the axial center of the bearing gap from escaping from the inflow passage. On the other hand, in reverse rotation of the rotary shaft, the switching valve is opened in order to prevent negative pressure from being generated in the bearing gap. As a result, the hydrodynamic bearing unit of the present invention can apply a radial load that acts on the rotary shaft when the rotary shaft rotates in both forward and reverse directions.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The dynamic pressure bearing unit of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows a first embodiment of a dynamic pressure bearing unit of the present invention in which air is used as a working fluid. In the figure, reference numeral 1 is a rotor in which a shaft (not shown) is inserted and fixed in a hollow portion, reference numeral 2 is a housing for attaching the rotor 1 to a fixed portion (not shown), and reference numeral 3 is the rotor 1 Radial bearings (hereinafter referred to as radial bearings) that rotatably support the rotor 2 with respect to the housing 2, and reference numerals 4 and 4 denote the rotor 1 with respect to the housing 2.
Is a pair of thrust dynamic pressure bearings (hereinafter referred to as thrust bearings) that regulate the axial movement of the.

The radial bearing 3 is composed of an inner ring 31 adhesively bonded to the rotor 1 and the housing (outer ring) 2 facing the inner ring 31 with a predetermined bearing gap (for example, 5 μm). In addition, a groove 32 for generating a dynamic pressure having a herringbone pattern as shown in FIG. 2 is formed on the peripheral surface of the inner ring 31. The dynamic pressure generating groove 32 has a depth of 20 μm and an inclination angle β = 3 with respect to the axial direction.
The groove was 0 °, and 15 grooves were continuously formed around the inner ring 31 having a diameter of 30 mm. The length Lg of the groove along the axial direction is set to 0.6 times the length L of the inner ring 31. In the present embodiment, the rotation in the direction of the arrow shown in FIG. 2 will be referred to as forward rotation, and the opposite rotation will be referred to as reverse rotation.

On the other hand, each thrust bearing 4 has a housing (fixed receiving plate) 2, a receiving plate (rotating receiving plate) 41 fixed to the rotor 1, and a predetermined bearing gap between the housing 2 and the receiving plate 41. The thrust plate 42 is held and opposed. The thrust plate 42 has an inner diameter larger than the outer diameter of the inner ring 31 by 30 μm, and is loosely fitted in the inner ring 31 with a gap. Further, the receiving plates 41, 41 are opposed to each other with the inner ring 31 sandwiched therebetween, and are fixed to the outer periphery of the rotor 1 by a lock nut 11 screwed to the end portion of the rotor 1. The inner ring 31 has an axial length in the housing 2 and a pair of thrust plates 42,
It is formed by 20 μm shorter than the sum of the axial lengths of 42. Therefore, in each thrust bearing 4, the thrust plate 4
A total bearing gap of 10 μm is secured above and below 2.

On the surface of the thrust plate 42 facing the housing 2, spiral grooves 43 as shown in FIG. 3 are equally formed. The spiral groove 43 is opened to the outer periphery of the thrust plate 42, and is closed to the through hole 44 in which the inner ring 31 is loosely fitted. Also, FIG.
As shown in FIG. 5, on the surface of the thrust plate 42 facing the receiving plate 41, a spiral groove 45 similar to the spiral groove 43.
Are formed with different twisting directions. Therefore, as shown in FIG. 3, the thrust plate 42 is inserted from the housing 2 side.
Looking at, the twisting direction of the spiral groove 45 is the same as that of the spiral groove 43. The spiral groove 4
The depth of 3,45 is 30 μm, and the inclination angle α with respect to the circumferential direction is
= 16 °, and 15 thrust plates 42 each having an outer diameter of 60 mm and an inner diameter of 30 mm were formed on each surface. 3 and 4, the forward rotation and the reverse rotation of the rotor 1 are indicated by arrows.

The material of the inner ring 31 and the thrust plate 42 is Al2O3, and the herringbone groove 32 and the spiral grooves 43 and 45 are formed by shot blasting. Other materials include SiC and Si3N
4, hard ceramics such as ZrO2 can be used. Further, as the material of the receiving plate 41 and the housing 2, stainless steel, ordinary cast iron or hard ceramics is used.

Further, in the present embodiment, the thrust plate 42 has an inner peripheral edge thickness of 10 μm than that of the outer peripheral edge.
The thickness is made thicker so that the thrust plate 42 and the housing 2 or the receiving plate 41 do not stick to each other even when the rotor 1 is stopped for a long time. For the same reason, the inner peripheral surface of the thrust plate 42 is processed into a convex curved surface. As a result, in the thrust bearing 4 of the present embodiment, even if dew condensation occurs due to water in the air, the thrust plate 42 does not stick to the housing 2 or the like, and the rotor 1 can be used for a long time without troublesome dew condensation prevention measures. It is possible to stop over.

On the other hand, the housing 2 is formed with an inflow passage 21 for supplying the air outside the housing 2 to the bearing gap of the radial bearing 3. This inflow path 21 is the housing 2
The inflow passages 21 are formed in three places so as to evenly distribute the circumference thereof, and each inflow passage 21 opens in the bearing gap of the radial bearing 3 at a position facing the center of the herringbone-shaped groove 32 of the inner ring 31. Further, each inflow passage 21 is connected to a switching valve 22 via a filter (not shown), and air outside the housing 2 is supplied to the radial bearing 3 according to opening / closing of the switching valve 22. . The switching valve 22 is closed when the rotor 1 rotates normally and is opened when the rotor 1 rotates reversely. The filter serves to remove dust, moisture and the like from the air sucked into the inflow passage 21.

Next, the operation of the dynamic pressure bearing unit of this embodiment will be described. FIG. 5 shows the flow of air in the bearing gap when the rotor 1 rotates forward. Rotor 1
When is rotated in the forward direction, the air between the receiving plate 41 and the thrust plate 42 is urged toward the center by the action of the spiral groove 45 formed in the thrust plate 42, and the thrust plate 4
Dynamic pressure is generated between 2 and the receiving plate 41. As a result, an air lubrication film against the thrust load acting on the rotor 1 is formed between the thrust plate 42 and the receiving plate 41, and fluid lubrication is performed between these plates 41 and 42. On the other hand, the thrust plate 42 receives the receiving plate 41 by the shearing force acting on the air lubrication film.
Therefore, the air between the thrust plate 42 and the housing 2 is urged in the outer peripheral direction by the action of the spiral groove 43 formed in the thrust plate 42, and the air between the thrust plate 42 and the housing 2 is urged. Negative pressure is generated during the period. Therefore, the thrust plate 42 is pulled toward the housing 2 and rotates at a slower speed than the receiving plate 41 due to the shearing force acting on the air lubrication film between the thrust plate 42 and the housing 2.

Since the inner peripheral surface of the thrust plate 42 is loosely fitted to the inner ring 31, the air urged as described above causes the front and back of the thrust plate 42 to rotate as the rotor 1 rotates. It will circulate. That is, assuming that the rotor 1 is rotating in the positive direction, the high-pressure air between the thrust plate 42 and the receiving plate 41 passes through the gap between the thrust plate 42 and the inner ring 31, and the negative pressure is generated. It flows into the gap between the plate 42 and the housing 2. Further, since the spiral grooves 43 and 45 formed in the thrust plate 42 are opened to the outer periphery of the thrust plate 42, when the thrust plate 42 rotates in the forward direction, the air outside the housing 2 will be in contact with the thrust plate 42 and the receiving plate. The air between the thrust plate 42 and the housing 2 is sucked between the housing 41 and the housing 41, and is discharged to the outside of the housing 2.
As a result, the air, which is the working fluid, circulates between the front and back surfaces of the thrust plate 42 as the rotor 1 rotates.

Further, since the bearing gap of the thrust bearing 4 and that of the radial bearing 3 are communicatively connected, a part of the air circulating in the thrust bearing 4 is supplied to the bearing gap of the radial bearing 3 in this manner. It Then, in the radial bearing 3, the herringbone-shaped groove 3 formed in the inner ring 31.
The air supplied from the thrust bearing 4 by 2 is urged toward the center of the herringbone groove 32. Since the switching valve 22 is closed when the rotor 1 rotates in the forward direction,
The urged air does not escape from the inflow passage 21,
Dynamic pressure is generated between the inner ring 31 and the housing 2. As a result, an air lubrication film against the radial load acting on the rotor 1 is formed between the inner ring 31 and the housing 2.

On the other hand, FIG. 6 shows the flow of air in the bearing gap when the rotor 1 rotates in the reverse direction. Rotor 1
Is rotated in the reverse direction, the air around the thrust plate 42 circulates in the thrust bearing 4 in the direction opposite to the normal rotation shown in FIG. 5, and a negative pressure is generated between the thrust plate 42 and the receiving plate 41. Meanwhile, dynamic pressure is generated between the thrust plate 42 and the housing 2. As a result, an air lubrication film is formed between the thrust plate 42 and the housing 2, and fluid lubrication against the thrust load acting on the rotor 1 is performed.

When the rotor 1 rotates in the reverse direction, the switching valve 2
2 is open, the inner ring 31 is
The air is urged toward the thrust plate 41 by the herringbone-shaped groove 32 formed at 1, and the air outside the housing 2 is supplied to the radial bearing 3 through the inflow path. At this time, since a high-pressure air lubrication film is formed around the thrust plate 42, the air urged toward the thrust plate 42 is also pressurized by the herringbone-shaped groove 32, and the inner ring 31 and the housing 2 are separated from each other. Dynamic pressure is generated during the period. As a result, an air lubrication film against the radial load acting on the rotor 1 is formed between the inner ring 31 and the housing 2.

Therefore, in the hydrodynamic bearing unit of this embodiment, the thrust load and the radial load can be applied in both the forward and reverse directions of the rotor 1.

Next, a second embodiment of the present invention shown in FIG. 7 will be described. The dynamic pressure bearing unit shown in this embodiment uses a lubricating liquid as the working fluid instead of air,
The specific structure is substantially the same as that of the first embodiment.
That is, the rotor 51 is rotatably held with respect to the housing 52 by the radial bearing 53 and the pair of thrust bearings 54. However, the lubricating oil is the thrust bearing 54
In order to prevent the oil from leaking out of the unit through the bearing gap, the lubricating oil can be sealed inside the unit.

The radial bearing 53 comprises an inner ring 81 adhered and bonded to the rotor 51, and the housing (outer ring) 52 facing the inner ring 81 with a predetermined bearing gap (for example, 5 μm). Cage, the inner ring 81
A groove 82 for generating a dynamic pressure having the same herringbone pattern as that shown in FIG. 2 in the first embodiment is formed on the peripheral surface of the above.

On the other hand, each thrust bearing 54 includes the housing (fixed receiving plate) 52, a receiving plate (rotary receiving plate) 91 fixed to the rotor 51, the housing 52 and the receiving plate 9.
Thrust plate 92 facing each other with a predetermined bearing gap maintained therebetween.
It consists of and. Also in this embodiment, the inner diameter of the thrust plate 92 is smaller than the outer diameter of the inner ring 81.
It is formed to be large by 0 μm, and is loosely fitted to the inner ring 81 with a gap maintained. Further, it is similar to the first embodiment in that the bearing plates 91, 91 and the inner ring 81 are fixed to the outer periphery of the rotor 51 by the set nut 61, and a bearing gap of 10 μm in total is secured above and below the thrust plate 92. .

On the surface of the thrust plate 92 facing the housing 52, as shown in FIG. 8, an annular groove 93 is formed slightly on the inner diameter side from the outer peripheral edge thereof, and the annular groove 93 is formed.
A spiral groove 94 similar to that of the first embodiment is provided on the inner diameter side.
Are formed so as to be evenly arranged, while a flat ridge portion is formed on the outer diameter side of the annular groove 93. The spiral groove 94 communicates with the annular groove 93, but closes to the central through hole 95. Also, as shown in FIG.
An annular groove 93 is provided on the surface of the thrust plate 92 facing the receiving plate 91.
An annular groove 96 similar to that of the spiral groove 9 is formed.
A spiral groove 97 similar to that of No. 4 is formed with different twist directions. Therefore, when the thrust plate 92 is viewed from the housing 52 side, the twisting direction of the spiral groove 97 is the same as that of the spiral groove 94. Each annular groove 9
3, 96 and the spiral grooves 94, 97 have the same depth, and in this embodiment, they have a depth of 30 μm. Incidentally, the thrust plate 92
Material, annular grooves 93, 96 and spiral grooves 94, 97
Since the processing of (1) is the same as that of the first embodiment, the description thereof is omitted here.

Further, the thrust plate 92 is made to communicate with the annular grooves 93 and 96 formed on the front and back sides thereof,
A circulation channel 98 is bored. In this embodiment, in consideration of the pressure balance acting on the thrust plate 92, the circulation flow passages 98 are formed at equal locations in three positions along the circumferential direction.

On the other hand, the housing 52 is provided with a supply passage 73 for supplying lubricating oil to a bearing gap formed by the thrust plate 92 and the housing 52.
Is open in the bearing gap at a position facing the annular groove 93 of the thrust plate 92. The supply passage 73 is connected to a reserve tank (not shown) via an outflow prevention valve 74. The outflow prevention valve 74 is opened when the rotor 51 rotates and closed when the rotor 51 is stopped.

Further, as in the first embodiment, the housing 52 is provided in the bearing gap of the radial bearing 53 in the housing 52.
An inflow path 71 for supplying outside air is formed, and each inflow path 71 is connected to a reserve tank (not shown) via a switching valve 72. The switching valve 72 is opened / closed in accordance with the rotation direction of the rotor 51, and when opened, the lubricating liquid in the reserve tank is supplied to the radial bearing 3.

In the hydrodynamic bearing unit of the present embodiment thus constructed, a highly viscous lubricating liquid is applied to the outer peripheral surface of the inner ring 81 and the front and back surfaces of the thrust plate 92 in advance, and the thrust plate 92 is also coated. The lubrication liquid is filled in the perforated circulation channel 98, the inflow channel formed in the housing 52, and the supply channels 71 and 73 for use.

In this embodiment, as in the first embodiment, when the rotor 51 rotates in either direction, dynamic pressure is generated in the radial dynamic pressure bearing and the thrust dynamic pressure bearing and acts on the rotor. Radial load and thrust load can be applied.

10 and 11 show the state of circulation of the lubricating liquid in this embodiment, and FIG. 10 shows the rotor 51.
11 corresponds to the forward rotation of the rotor 51, and FIG. 11 corresponds to the reverse rotation of the rotor 51. As shown in FIG. 10, when the rotor 51 rotates in the forward direction, the lubricating liquid between the thrust plate 92 and the receiving plate 91 is urged toward the center by the action of the spiral groove 97 formed in the thrust plate 92. , The thrust plate 92 and the housing 5 through the gap between the thrust plate 92 and the inner ring 81.
It flows into the gap with 2. On the other hand, the lubricating liquid between the thrust plate 92 and the housing 52 is urged in the outer peripheral direction by the action of the spiral groove 94.
Since 4 is in communication with the annular groove 93, the lubricating liquid flows into the annular groove 93 and is prevented from moving in the outer peripheral direction,
It flows into the gap between the thrust plate 92 and the receiving plate 91 through the circulation flow path 98 formed in the thrust plate 92. At this time,
Since the spiral groove 94 is formed on the inner peripheral side of the annular groove 93 and the outer peripheral side of the annular groove 93 is a ridge portion, the lubricating liquid biased in the outer peripheral direction acts on the thrust plate 92. It does not leak from the gap with the housing 52. That is, the lubricating liquid is the thrust plate 92 and the housing 5
It is circulated between the front and back of the thrust plate 92 without being discharged to the outside through the gap between the thrust plate 92 and the second plate.

Also, as shown in FIG. 11, when the rotor 51 rotates in the opposite direction, the thrust plate 92 and the housing 52 are rotated.
The lubricating liquid between and is urged toward the center by the action of the spiral groove 94 formed in the thrust plate 92, and the gap between the thrust plate 92 and the receiving plate 91 is passed through the gap between the thrust plate 92 and the inner ring 81. Flow into. On the other hand, the lubricating liquid between the thrust plate 92 and the receiving plate 91 is urged in the outer peripheral direction by the action of the spiral groove 97, but the spiral groove 9
Since 7 communicates with the annular groove 96, the lubricating liquid flows into the annular groove 96 and is prevented from moving in the outer peripheral direction.
It flows into the gap between the thrust plate 92 and the housing 52 via the circulation flow path 98 formed in the thrust plate 92. At this time, since the spiral groove 97 is formed on the inner peripheral side of the annular groove 96 and the outer peripheral side of the annular groove 96 is a ridge portion, the lubricating liquid urged in the outer peripheral direction is thrust. It does not leak out from the gap between the plate 92 and the receiving plate 91. That is, also in this case, the lubricating liquid circulates between the front and back surfaces of the thrust plate 92 without being discharged to the outside through the gap between the thrust plate 92 and the receiving plate 91.

As described above, in the hydrodynamic bearing unit according to the present embodiment, the lubricating liquid previously applied between the receiving plate 91, the thrust plate 92 and the housing 52 circulates between the front and back of the thrust plate 92, and the circulation is performed. Accordingly, fluid lubrication is performed between the thrust plate 92 and the receiving plate 91, or between the thrust plate 92 and the housing 52. Therefore, the lubricating liquid hardly leaks from between the thrust plate 21 and the receiving plate 91 or the housing 52 even when the rotor 51 is stopped.
Moreover, fluid or foreign matter does not enter between the thrust plate 92 and the receiving plate 91 or the housing 52 from the outside of the unit.

Therefore, even when used in pumped water containing slurry such as a pump pumping channel, the slurry is not caught in the bearing unit and damage to the thrust plate 92, the receiving plate 91 and the housing 52 can be prevented. .

Further, in this embodiment, a reserve tank for lubricating liquid is provided, and the reserve tank and the bearing gap of the thrust bearing 54 are communicated with each other by the supply passage 73. Therefore, if a negative pressure acts on the bearing gap, Is supplied to the gap between the thrust plate 92 and the housing 52. Therefore, it is possible to replenish the lubricating liquid that has leaked out from the thrust bearing 94 little by little, and the solid contact between the thrust plate 92 and the receiving plate 91 or the thrust plate 92 and the housing 52 due to lack of the lubricating liquid. Can be prevented.

Further, when the rotor 51 is stopped, the inflow passage 71
If both the switching valve 72 and the outflow prevention valve 74 of the supply path 73 are closed, the radial bearing 53 and the thrust bearing 5
It is possible to prevent the lubricating liquid from leaking out from the bearing clearance of No. 4, and it is possible to restart the rotor 51 with a small starting torque.

In the second embodiment, the exclusive lubricating liquid is used as the working fluid. However, when this dynamic pressure bearing unit is used as the submersible bearing in the axial flow pump, pumping water of the pump is used as the working fluid. It can also be used.

In this case, no reserve tanks are required for the inflow passage and the supply passage, the inflow passage 71 is opened to the pumping water via the switching valve 72, and the supply passage 73 is also opened to the pumping water via the outflow prevention valve 74. It will be released. As a result, when the hydrodynamic bearing unit of the present embodiment is submerged in pumping water, pumping water circulates inside the bearing as described above according to the rotation direction of the rotor 51, and the rotor 51 rotates radially in both directions. Loads and thrust loads can be applied.

Even if the hydrodynamic bearing unit of this embodiment is exposed from the pumping water due to the stop of the pump, by closing the switching valve 72 and the outflow prevention valve 74,
Since pumped water can be retained in the bearing gap between the radial bearing 53 and the thrust bearing 54, solid contact does not occur inside the bearing unit even when the pump is restarted, and a small starting torque is generated. The rotor 51 can be restarted with.

[0056]

As described above, according to the hydrodynamic bearing unit of the present invention, the thrust hydrodynamic bearings capable of rotating in both forward and reverse directions are provided at both ends of the radial hydrodynamic bearing, and the bearing of the hydrodynamic bearing is provided. Since the gaps are connected to each other and the inflow passage for supplying the working fluid to the bearing gap of the radial dynamic pressure bearing is opened / closed in accordance with the rotation direction of the rotary shaft, the rotary shaft of the radial dynamic pressure bearing has the opposite direction. Even if the shaft rotates, the dynamic pressure that is large enough to apply the radial load that acts on the rotating shaft can be generated at both ends of the bearing gap, and the rotating shaft rotates in both forward and reverse directions. Radial load and thrust load acting on the shaft can be applied.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of a dynamic pressure bearing unit of the present invention.

FIG. 2 is a front view showing an inner ring of the radial dynamic pressure bearing according to the first embodiment.

FIG. 3 is a plan view of a thrust plate of the thrust dynamic pressure bearing according to the first embodiment.

FIG. 4 is a bottom view of a thrust plate of the thrust dynamic pressure bearing according to the first embodiment.

FIG. 5 shows a state of air circulation in forward rotation of the dynamic pressure bearing unit of the first embodiment.

FIG. 6 shows a state of air circulation during reverse rotation of the dynamic pressure bearing unit of the first embodiment.

FIG. 7 is a sectional view showing a second embodiment of the dynamic pressure bearing unit of the present invention.

FIG. 8 is a plan view of a thrust plate of a thrust dynamic pressure bearing according to a second embodiment.

FIG. 9 is a bottom view of the thrust plate of the thrust dynamic pressure bearing according to the second embodiment.

FIG. 10 is a diagram showing a state of circulation of a lubricating liquid in forward rotation of the dynamic pressure bearing unit of the second embodiment.

FIG. 11 shows a state of circulation of a lubricating liquid in the reverse rotation of the dynamic pressure bearing unit of the second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rotor (rotating shaft), 2 ... Housing, 3 ... Radial dynamic pressure bearing, 4 ... Thrust dynamic pressure bearing, 21 ... Inflow path, 22
... Switching valve, 31 ... Inner ring, 32 ... Herringbone groove, 4
DESCRIPTION OF SYMBOLS 1 ... Receiving plate (rotary receiving plate), 42 ... Thrust plate, 43, 45
… Spiral groove

Claims (4)

[Claims] 1. A housing, a radial dynamic pressure bearing that rotatably supports a rotary shaft that penetrates the housing with respect to the housing, and a pair of thrust dynamic pressure bearings, and the radial dynamic pressure bearing has a predetermined size. It has an inner ring and an outer ring facing each other through a bearing gap, and a herringbone groove is formed in the inner ring or the outer ring, while the thrust dynamic pressure bearing has a fixed bearing plate, a rotary bearing plate, and these bearing plates. The thrust plates are opposed to each other with a bearing gap, and spiral grooves are formed on the front and back sides of the thrust plate in directions opposite to each other when viewed from the respective surface sides, and a pair of thrust plates are provided at both ends of the radial dynamic pressure bearing. Is loosely fitted to the rotary shaft to connect the bearing gaps of the thrust dynamic pressure bearings to the bearing gaps of the radial dynamic pressure bearings, and the housings of the radial dynamic pressure bearings are connected to the housing. To form the inlet passage for supplying the working fluid between, depending on the rotational direction of the rotary shaft dynamic bearing unit, characterized in that a switching valve for opening and closing the inlet channel. 2. A flat lid portion is formed on the outer peripheral side of a spiral groove formed on both front and back surfaces of the thrust plate, and the thrust plate is penetrated at the boundary between the spiral groove and the lid portion. The dynamic pressure bearing unit according to claim 1, wherein a circulating flow path is formed. 3. A supply path for supplying a working fluid to the bearing gap of the thrust bearing is formed in the fixed receiving plate, and
The hydrodynamic bearing unit according to claim 2, further comprising an outflow prevention valve that closes the supply passage when the rotating shaft is stopped. 4. The hydrodynamic bearing unit according to claim 1, wherein the thrust plate has an outer peripheral edge thinner than an inner peripheral edge.