JP2002286037A - Variable nozzle type hydrostatic bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control damage and wear between a movable object and an inner wall of a bearing main body caused by a collision and contact between the movable object in which an oriffice is formed and the inner wall of the bearing main body and also to secure smooth motion of the movable object. SOLUTION: Fluid flowing into a third fixed oriffice 38 flows out to a side pocket 36 and then flows into a clearance 32. The fluid flowed in to the clearance 32 forms a fluid film between the inner wall of an upper portion 10A of the bearing main body and the movable object 14. The fluid film becomes buffer material when the movable object 14 keeps in contact with or collides with an inner wall surface of the upper portion 10A of the bearing main body. Thus, the upper portion 10A of the bearing main body and movable object 14 can be protected from wear and damage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable throttle type hydrostatic bearing, and more particularly to a variable throttle type hydrostatic bearing having a plurality of throttles.

[0002]

2. Description of the Related Art Various techniques have conventionally been proposed as a variable throttle type hydrostatic bearing. For example, Japanese Patent No. 1888555 proposes a technique in which a second-stage diaphragm of the two-stage diaphragm is formed on a movable object, and the outline thereof is as follows. Figure 1
As shown in FIG. 4, the bearing in which the second-stage throttle of the two-stage throttle is formed on a movable object includes a fluid supply port 80, a first-stage fixed throttle 82, a second-stage fixed throttle 84, and a fluid discharge port 8
6 is provided. The fluid that has entered from the fluid supply port 80 passes through the first-stage fixed throttle 82 and flows into the lower pocket 88. Thereafter, the fluid splits in two directions, and one of the fluids passes through the second-stage fixed throttle 84 and enters the upper pocket portion 90, and then passes through the gap 96 between the load shaft 92 and the upper surface of the bearing body 94, and becomes external. Is discharged. The other one of the fluids passes through the lower part of the second fixed throttle 84 and passes through the fluid outlet 8.
Exhausted from 6. With such a bearing structure, the following pressure compensation action can be obtained.

Now, when the load on the load shaft 92 increases from a certain balanced state, the load shaft 92 is displaced downward in FIG. Then, the gap 96 on the lower side of the load shaft 92 becomes narrower, and the flow rate of the fluid passing through the gap 96 decreases, so that the upper pocket portion 90 located on the lower side of the load shaft 92
The pressure inside rises. Due to this increase in pressure, the movable object is pushed downward. Conversely, the pressure in the upper pocket portion 90 located on the upper side of the load shaft 92 decreases. As described above, the pressure in the upper pocket portion 90 increases, and the movable object is displaced downward by the balance of the fluid force applied to the movable object. As a result, the gap between the lower portion of the second-stage fixed throttle 84 and the inlet of the fluid discharge port 86 is narrowed, and the discharge flow rate is reduced. As a result, the lower pocket 8 of the first stage fixed aperture 82
As the internal pressure increases, the fluid from the lower pocket 88 flows through the second fixed throttle 84 made of a movable object, flows into the upper pocket 90, and increases the pressure to prevent the displacement of the load shaft 92.

However, in the above-described aperture bearing using a movable object, the second-stage aperture is formed in the movable object, so that when the load from the load shaft changes or the movable object moves. Then, the movable object comes into contact with or collides with the bearing body. For this reason, there has been a problem that the movable object and the bearing main body are damaged or worn by friction or impact due to contact or collision, or that the movable object is prevented from moving smoothly.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and damages or wears the movable object and the inner wall of the bearing body due to the collision or contact between the movable object having the aperture formed therein and the inner wall of the bearing body. It is an object of the present invention to provide a variable-aperture-type hydrostatic bearing capable of suppressing such a problem and ensuring a smooth operation of a movable object.

[0006]

In order to solve the above-mentioned problems, a variable throttle type hydrostatic bearing according to the present invention comprises a fluid supply port for supplying a fluid, and a flow rate of the fluid supplied from the fluid supply port. A first fixed restrictor for restricting the flow into the bearing body, and a fluid discharge port for discharging the fluid that has flowed therein, the bearing body being spaced from the load shaft, and moving into the bearing body. The bearing main body is divided into a first chamber on the load shaft side and a second chamber communicated with the first fixed throttle and the fluid discharge port. Fluid flowing from the first room to the second room through the second room and the first room
A second fixed throttle that throttles the flow rate of at least one of the fluids flowing into the chamber, and one end that opens to the second chamber and the other end opens to a contact portion with the inner wall of the bearing body, A movable object on which a third fixed throttle for reducing the flow rate of the fluid toward the inner wall is formed.

According to the present invention, when the load shaft is displaced, the fluid pressure in the first chamber increases, and the movable object is displaced toward the first fixed throttle. Due to this displacement, the fluid pressure in the second chamber increases, and the fluid flowing from the first fixed throttle flows into the first chamber through the second fixed throttle to increase the pressure to prevent displacement of the load shaft. At the same time, the fluid that has flowed in from the first fixed throttle passes through a third fixed throttle formed in the movable object and flows out into a gap formed between the inner wall of the bearing main body and the facing portion of the movable object, and flows out of the gap. Since a fluid film is formed on the movable body, damage and wear of the movable body and the inner wall of the bearing body due to collision or friction between the movable body and the bearing body when the movable body is displaced due to a change in the load shaft, etc. Smooth operation can be ensured.

It is to be noted that the present invention provides a first fixed aperture and a second fixed aperture.
At least one of the fixed diaphragms may be a diaphragm formed by a porous body.

The present invention also provides a first fixed aperture and a second fixed aperture.
At least one of the fixed diaphragms may be a diaphragm using a capillary hole.

In the present invention, the first fixed aperture may be an aperture formed by a capillary hole, and the second fixed aperture may be an aperture formed by a porous body formed in a porous body.

Further, the first fixed diaphragm may be a diaphragm formed by a porous body, and the second fixed diaphragm may be a diaphragm formed by a capillary hole.

Further, according to the present invention, the first fixed aperture can be an aperture formed by an orifice effect.

Further, according to the present invention, a variable throttle type hydrostatic thrust bearing can be constituted by using the variable throttle type hydrostatic bearing according to any one of claims 1 to 6 as a thrust bearing.

Further, according to the present invention, a variable throttle type hydrostatic journal bearing as a journal bearing can be constituted by using a plurality of variable throttle type hydrostatic thrust bearings according to the present invention.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a variable throttle type hydrostatic bearing according to the present invention will be described below with reference to the drawings. [First Embodiment] As shown in FIGS. 1 and 2, a variable throttle type hydrostatic bearing 12 of the present embodiment constitutes a thrust bearing, and includes a bearing main body upper portion 10A, a bearing main body lower portion 10B, and a movable object. 14.

As shown in FIGS. 1 and 3, the upper portion 10A of the variable throttle type hydrostatic bearing 12 has a movable diaphragm portion 22 penetrating the center portion, an upper pocket 20 on the load shaft 16 side, and an upper pocket. A lower pocket 24 is formed on the side opposite to 20. The load shaft 16 and the variable throttle type hydrostatic bearing 12 are disposed with a gap 18 therebetween, and the upper pocket 20 side is in contact with the load shaft 16 via the gap 18. In addition, a passage 46 is formed in the upper part 10A of the bearing main body to communicate the upper pocket 20 and a side surface of the upper part 10A of the bearing main body.
A pressure gauge 26 is installed at the side exit of the upper part 10A of the bearing body 6 of FIG.

The movable object 14 is fitted to the movable diaphragm unit 22 through the gap 32 and moves up and down inside the movable movable diaphragm unit 22. An upper pocket 34 is formed on the load shaft 16 side of the movable object 14, and a first room is formed by the upper pocket 34, the upper pocket 20, and the movable part 22. A cylindrical magnet 30 joined to the plate 28 is attached to the outer periphery of the yoke portion 14A of the movable object 14. Side pockets 36 are formed at four equally spaced positions on the outer peripheral side surface of the movable object 14. Movable object 14
The third fixed throttle 38 is connected to one side pocket 36 from one central portion of the lower side of the bearing body 10B.
Are perforated. The movable object 14 is provided with two second fixed diaphragms 40 communicating with the upper and lower surfaces of the movable object 14 at two locations.

The lower bearing body 10B has an upper bearing body 1
A convex portion 54 is formed at a central portion on the side in contact with 0A, and an annular pocket 56 is formed outside the convex portion 54. A voice coil 58 is installed in the annular pocket 56. The cylindrical magnet 30 has a projection 54 and a voice coil 58.
The movable object 14 is in a floating state above the protrusion 54 via the gap 22. Voice coil 58
Is connected to the control device 60, and the control device 60
Is connected to a position sensor 62 for detecting the position of the position. A lower pocket 48 is formed at the tip of the convex portion 54, and a fluid supply port 42 is formed on a surface opposite to the convex portion 54. First fixed aperture 50 comprising a capillary hole
Are perforated to communicate the lower pocket 48 and the fluid supply port 42. On the fluid outflow side of the first fixed throttle 50, a second chamber is formed by the movable object 14 and the lower pocket 48. A fluid discharge path 66 that connects the outer peripheral surface of the lower bearing body 10B to the bottom of the annular pocket 56, and a fluid discharge path 66
The fluid supply port 42 communicates with the outer peripheral surface on the side opposite to the outlet of the fluid supply port 42.

Next, the operation of the variable throttle type hydrostatic bearing of this embodiment will be described.

As shown in FIG. 3, the fluid entering from the fluid supply passage 42 passes through the first fixed throttle 50 and enters the lower pocket portion 48. Thereafter, the fluid splits in three directions: The first flow direction of the fluid passes through the second fixed throttle 40 formed on the movable object 14, flows out into the upper pocket 34, enters the upper pocket 20 via the throttle movable part 22,
After that, it is discharged to the outside of the bearing through the gap 18. The second flow direction of the fluid is the gap 6 below the movable object 14.
8, the fluid enters the annular pocket 56, and is discharged from the fluid discharge passage 66. The third flow direction of the fluid flows out through the third fixed throttle 38 into the side pocket 36, out into the gap 32 between the inner wall of the upper part 10A of the bearing body and the movable object 14, and then into the annular shape. It flows to the pocket 48 and is discharged from the fluid discharge path 66.

When the load on the load shaft 16 increases from a certain balanced state, the load shaft 16 is displaced downward from the state shown in FIG. Then, the gap 18 becomes narrow, and the gap 1
As the fluid flow through 8 decreases, the pressure in the first chamber increases. This increase in pressure pushes the movable object 14 downward.

When pushed down, the movable object 14
The diaphragm movable part 22 is moved downward, but the balance of the movable object in a floating state is lost.
It moves downward while contacting or colliding with the inner wall surface of the. When the movable object 14 is pushed downward, the gap between the gap 68 at the lower portion of the movable object 14 and the convex portion 54 becomes narrow, and the discharge flow rate of the fluid decreases. As a result, the pressure in the second chamber increases, and most of the fluid flowing out of the first fixed throttle 50 flows into the third fixed throttle 38 and the second fixed throttle 40. The fluid that has flowed into the second fixed throttle 40 flows out into the upper pocket portion 20 and increases the pressure in the first chamber to prevent the displacement of the load shaft 16.

The fluid flowing into the third fixed throttle 38 flows out into the side pocket 36 and flows into the gap 32. Gap 3
2 forms a fluid film between the inner wall of the upper part 10A of the bearing body and the movable object 14, and a buffer material when the movable object 14 contacts or collides with the inner wall surface of the upper part 10A of the bearing body. And the upper part 10A of the bearing body and the movable object 14
Is prevented from being worn or damaged, and smooth operation of the movable object 14 is ensured.

As described above, the third fixed throttle 38 is provided on an infinitely rigid bearing consisting of a plurality of throttles, in which the gap between the load shaft and the bearing does not change even if the load changes theoretically. As a result, the fluid is poured between the movable object 14 and the inner wall surface of the upper portion 10A of the bearing main body to form a film of the fluid, and when the load from the load shaft changes or the second fixed throttle moves. Damage and wear due to contact with the upper part 10A of the bearing body can be suppressed.

FIG. 4A is a graph comparing the relationship between the load capacity W of the bearing and the lateral load capacity Wf when the third fixed throttle 38 is formed and when it is not formed.
From this graph, when the third fixed throttle 38 is formed, a linear relationship that the load capacity in the lateral direction increases in proportion to the load capacity of the bearing is obtained, and the third fixed throttle 38 is obtained.
It can be seen that there is a relationship that the load capacity in the lateral direction hardly changes even if the load capacity of the bearing increases, when no is formed. From this result, it can be seen that the formation of the third fixed aperture 38 can suppress damage, wear, and the like of the movable object 14 and the inner wall surface of the upper portion 10A of the bearing body.

FIG. 4B shows a third fixed stop 38.
4 is a graph showing the relationship between the load capacity W of the bearing and the lateral load capacity Wf when the diameter of the capillary is changed. When the capillary diameter is 0.10mm, the bearing's load capacity W
, The load capacity Wf in the horizontal direction becomes large, and when the capillary diameter is 0.20 mm, the load capacity Wf in the horizontal direction is about half that in the case where the capillary diameter is 0.10 mm. When the diameter of the capillary is 0.30 mm or more, the load capacity Wf in the lateral direction is extremely low as compared with the case where the diameter of the capillary is 0.10 mm. Therefore, it is preferable that the capillary diameter of the third fixed aperture 38 is 0.10 mm to 0.20 mm.

FIG. 4C shows the gap 18 between the load shaft 16 and the bearing body 10 = h2, the gap 68 between the first fixed aperture 50 and the movable object 14 = h1 and the load capacity W of the bearing. 6 is a graph showing the relationship of. Here, "Ps" indicates the fluid pressure from the fluid supply port 42, and it can be seen that both h1 and h2 are almost unaffected by Ps and take a specific value for the load capacity of the bearing.

Further, the variable throttle type hydrostatic bearing of the present invention may be a variable throttle type hydrostatic bearing having a configuration different from that of the variable throttle type hydrostatic bearing of the above embodiment. A variable throttle type hydrostatic bearing having another configuration will be described as a second embodiment with reference to the drawings. The same parts as those of the variable throttle type hydrostatic bearing according to the first embodiment will be described with the same reference numerals.

[Second Embodiment] As shown in FIG.
A fluid supply port 42 and a fluid discharge path 66 are formed in the bearing body 10 of the variable-aperture-type hydrostatic bearing 12, and an object 50A having the first fixed aperture 50 formed therein and the movable object 14 are incorporated therein. ing. The fixed object 50A has a lower pocket 46 formed on the fluid outflow side, and a first fixed throttle 50 formed to penetrate the upper and lower surfaces. An upper pocket 20 is formed in the movable object 14 on the fluid outflow side, and a second fixed throttle 40 formed by a capillary hole is formed so as to penetrate the upper and lower surfaces. Side pockets 36 are formed at four equally-spaced positions on the outer peripheral side surface of the movable object 14, and a third fixed throttle 38 is provided so as to communicate with the side pocket 36 from the fluid inflow side of the movable object 14. Are formed. The load shaft 16 and the variable throttle type hydrostatic bearing 12 are disposed with a gap 18 therebetween, and the upper pocket 20 side is in contact with the load shaft 16 via the gap 18.

The operation of the variable throttle type hydrostatic bearing of the present embodiment is the same as that of the variable throttle type hydrostatic bearing of the above-described first embodiment, and therefore the description thereof is omitted.

Also in the present embodiment, since a fluid film is formed in the gap 32 between the inner wall surface of the bearing body 10 and the movable object 14 by the fluid flowing out of the third fixed throttle 38, Bearing body 1 when object 14 is displaced
As a cushioning material for collision or contact with the inner wall surface of the movable body 14, the inner wall of the movable body 14 and the bearing body 10 can be prevented from being damaged or worn. .

In the above two embodiments, the example of the thrust bearing has been described, but the present invention can be applied to a journal bearing. That is, by similarly providing a flow path in the second fixed throttle for the journal bearing, the fluid is poured between the second fixed throttle and the inner wall surface of the bearing body to form a fluid film, and the movable object It is possible to reduce damage, abrasion, and the like caused by contact with the bearing main body when the second fixed throttle is moved. FIG. 6 schematically shows an example in which the variable throttle type hydrostatic bearing according to the second embodiment is applied to a journal bearing.

In the above two embodiments, the first embodiment
Although the aperture using a capillary hole is used as the fixed aperture and the second fixed aperture, apertures formed by a porous body formed on a porous object may be used as the first fixed aperture and the second fixed aperture. In addition, it is also possible to use a diaphragm with a capillary hole as the first fixed diaphragm and to use a diaphragm with a hole formed in a porous object as the second fixed diaphragm, or to use a porous diaphragm as the first fixed diaphragm by reversing the diaphragm used. It is also possible to use a diaphragm with a capillary hole as a second fixed diaphragm using a diaphragm with a hole formed in the object. FIG.
As shown in FIG.

FIG. 7 shows an example of a thrust bearing using apertures formed on a porous body for the first fixed aperture and the second fixed aperture, and FIG. 8 shows the first fixed aperture and the second fixed aperture. FIG. 9 shows an example of a journal bearing using a porous fixed aperture formed in a porous body as a second fixed aperture. FIG. 9 shows a first fixed aperture used as a capillary aperture and a second fixed aperture used as a porous fixed aperture. FIG. 10 shows an example of a thrust bearing using a throttle formed by a hole formed in an object. FIG. 10 shows a case in which a first fixed throttle is formed by a capillary hole and a second fixed throttle is formed by a hole formed in a porous object. FIG. 11 is an example of a journal bearing using a throttle, and FIG. 11 shows a thrust bearing using a throttle using a porous hole formed in a porous body as a first fixed throttle and a throttle using a capillary hole as a second fixed throttle. FIG. 12 is an example.
Is an example of a journal bearing in which a first fixed aperture uses an aperture formed by a porous body and a second fixed aperture uses a capillary aperture.

As shown in FIG. 13, a journal bearing can be formed by using a plurality of thrust bearings of the above-described embodiment.

[0036]

As described above, according to the present invention,
When the load shaft is displaced, the fluid pressure in the first chamber increases, and the movable object is displaced toward the first fixed throttle. Due to this displacement, the fluid pressure in the second chamber increases, and the fluid flowing from the first fixed throttle flows into the first chamber through the second fixed throttle to increase the pressure to prevent displacement of the load shaft. With the first
The fluid that has flowed in from the fixed restrictor flows through a third fixed restrictor formed in the movable object, flows out into a gap formed between the inner wall of the bearing main body and the opposing portion of the movable object, and forms a fluid film in the gap. Because of this, damage and wear of the movable object and the inner wall of the bearing body due to collision or friction between the movable object and the bearing body when the movable object is displaced due to fluctuation of the load axis etc., and ensure smooth operation of the movable object Can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a variable throttle type hydrostatic bearing according to a first embodiment.

FIG. 2 is a schematic configuration diagram of a variable throttle type hydrostatic bearing according to the first embodiment.

FIG. 3 is an enlarged cross-sectional view of the movable object according to the first embodiment and the periphery thereof.

FIG. 4A is a diagram comparing the relationship between the load capacity of a bearing and the load capacity in the lateral direction when a third fixed throttle is formed and when it is not formed, and FIG. It is a figure which compared the relationship between the load capacity of a bearing corresponding to the change of the capillary diameter of a fixed throttle, and the load capacity of a horizontal direction, (C) is the clearance (h2) of a load shaft and a bearing, and the 1st fixed throttle. It is a graph which shows the relationship between the clearance gap (h1) of a movable object, and the load capacity of a bearing.

FIG. 5 is a schematic sectional view of a variable throttle type hydrostatic bearing according to a second embodiment.

FIG. 6 is a schematic cross-sectional view of a case where the variable throttle type hydrostatic bearing of the second embodiment is applied to a journal bearing. Gap

FIG. 7 is a schematic cross-sectional view of another example in which the variable throttle type hydrostatic bearing of the second embodiment is applied to a thrust bearing.

FIG. 8 is a schematic cross-sectional view of another example in which the variable throttle type hydrostatic bearing of the second embodiment is applied to a journal bearing.

FIG. 9 is a schematic cross-sectional view of another example in which the variable throttle type hydrostatic bearing of the second embodiment is applied to a thrust bearing.

FIG. 10 is a schematic cross-sectional view of another example in which the variable throttle type hydrostatic bearing of the second embodiment is applied to a journal bearing.

FIG. 11 is a schematic cross-sectional view of another example in which the variable throttle type hydrostatic bearing of the second embodiment is applied to a thrust bearing.

FIG. 12 is a schematic cross-sectional view of another example in which the variable throttle type hydrostatic bearing of the second embodiment is applied to a journal bearing.

FIG. 13 is a schematic cross-sectional view of a configuration in which a journal bearing is formed using a plurality of variable throttle type hydrostatic bearings according to the second embodiment.

FIG. 14 is an example of a conventional variable throttle type static pressure bearing.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Bearing main body 12 Variable throttle type static pressure bearing 14 Movable object 16 Load shaft 18 Gap 20 Upper pocket 22 Throttle movable part 24 Lower pocket 26 Pressure gauge 32 Gap 34 Upper pocket 36 Side pocket 38 Third fixed throttle 40 Second Fixed throttle 42 Fluid supply port 46 Passage 48 Lower pocket 50 First fixed throttle 54 Convex portion 56 Annular pocket 64 Flow path 66 Fluid discharge path 68 Gap

Claims (8)

[Claims] 1. A fluid supply port for supplying a fluid, a first fixed throttle for restricting a flow rate of the fluid supplied from the fluid supply port to flow into the inside, and a fluid discharge for discharging the flowed fluid. A bearing body provided with an outlet and arranged at a distance from a load shaft; a first chamber movably housed inside the bearing body, and having the inside of the bearing body on a load shaft side; And a second chamber communicated with the fixed throttle and the fluid discharge port, and the first chamber communicates with the second chamber to form the first chamber.
A second fixed throttle for reducing the flow rate of at least one of the fluid flowing from the room to the second room and the fluid flowing from the second room to the first room, and one end open to the second room and the other. A movable object having an end opened at a portion facing the inner wall of the bearing main body and a third fixed restrictor formed to reduce a flow rate of fluid toward the inner wall of the bearing main body; . 2. A variable throttle type static pressure according to claim 1, wherein at least one of said first fixed throttle and said second fixed throttle is a throttle made of a porous material. bearing. 3. The variable throttle type hydrostatic bearing according to claim 1, wherein at least one of the first fixed throttle and the second fixed throttle is a throttle formed by a capillary hole. 4. The variable according to claim 1, wherein the first fixed stop is a stop formed by a capillary hole, and the second fixed stop is a stop formed by a hole formed in a porous object. Throttle type hydrostatic bearing. 5. The variable according to claim 1, wherein the first fixed aperture is an aperture formed by a porous body, and the second fixed aperture is a capillary aperture. Throttle type hydrostatic bearing. 6. The variable throttle type hydrostatic bearing according to claim 1, wherein said first fixed throttle is a throttle by an orifice effect. 7. A variable throttle type hydrostatic bearing, wherein the variable throttle type hydrostatic bearing according to any one of claims 1 to 6 is a thrust bearing. 8. A variable throttle type hydrostatic bearing comprising a journal bearing by using a plurality of variable throttle type hydrostatic bearings according to claim 7.