JP2021080986A - Fluid bearing device - Google Patents

Abstract

To provide a fluid bearing device which can stably measure a swing amount of a rotary shaft body during rotation with high accuracy.SOLUTION: A fluid bearing device 1 includes: a fluid supply part which supplies a fluid to the inside of a fluid bearing body 3; a measuring plate 31 which is disposed spaced apart from an outer periphery of a rotary shaft body 2 and disposed through a fluid film formed in a gap by the fluid; a support member 32 which elastically supports the measuring plate 31 in a manner that the measuring plate 31 can move in a radial direction relative to the fluid bearing body 3 and cannot rotate; and a displacement sensor 40 which is integrally disposed with the fluid bearing body 3 and measures displacement of a distance between itself and the measuring plate 31.SELECTED DRAWING: Figure 2

Description

The present invention relates to a fluid bearing device.

Conventionally, in a fluid bearing device, a technique for suppressing a decrease in accuracy of a moving body due to a disturbance load fluctuating at high speed has been proposed (see, for example, Patent Document 1 and the like). This fluid bearing device is provided with a displacement sensor that measures the relative displacement between the moving body and the fluid bearing body as a means for detecting the amount of vibration of the moving body, and moves forward and backward in the static pressure pocket according to the measured relative displacement. By doing so, the relative displacement between the fluid bearing main body and the moving body due to the disturbance force is suppressed, and the deterioration of the accuracy of the fluid holding device due to the disturbance force is suppressed.

Japanese Unexamined Patent Publication No. 2011-75072

In the conventional fluid bearing device described above, the moving body to be measured is moving, and a fluid such as water or oil exists between the moving body and the displacement sensor. Therefore, when the rotating shaft body of high-speed rotation is a moving body, the contact type displacement sensor cannot be used. Further, even in the non-contact type displacement sensor, the capacitance type or laser type sensor cannot be used in the environment of water or oil. On the other hand, the eddy current type displacement sensor is resistant to water and oil and has excellent environmental resistance.

However, the eddy current type displacement sensor has no problem in measuring the same part of the object, but the surface such as the rotating shaft body having variations in material characteristics continuously changes due to rotation. , It is known that displacement measurement is difficult. This is due to the influence of electrical runout due to uneven material of the object and residual stress.

An object of the present invention is to provide a fluid bearing device capable of stably and accurately measuring the amount of runout of a rotating shaft body during rotation.

The fluid bearing device according to the present invention is a fluid bearing device that supports the rotating shaft body by the pressure of the fluid filled between the rotating shaft body and the fluid bearing body, and the fluid is placed in the fluid bearing body. A fluid supply unit to be supplied, a measuring plate arranged on the outer periphery of the rotating shaft body with a gap, and a measuring plate arranged via a fluid film formed in the gap by the fluid, and the measuring plate are the fluid bearing main body. It is provided with a support member that is movable in the radial direction and elastically supports it so as not to rotate, and a displacement sensor that is integrally arranged in the fluid bearing body and measures the displacement of the distance from the measuring plate.

According to this configuration, when the rotating shaft body swings, the measuring plate arranged via the fluid film is elastically supported by the support member so as to be movable in the radial direction and non-rotatably. It moves according to the amount of swing of the body. When the measuring plate moves, the displacement of the distance from the measuring plate is measured by the displacement sensor integrally arranged on the fluid bearing body. Therefore, by measuring the displacement of the measuring plate that moves according to the runout of the rotating shaft body, it is possible to stably measure the amount of runout of the rotating shaft body during rotation with high accuracy.

It is an overall block diagram which shows the outline of the fluid bearing apparatus which concerns on 1st Embodiment. It is explanatory drawing which shows the structure of the shaft displacement measuring mechanism which concerns on 1st Embodiment. It is a perspective view which shows the measuring plate which concerns on 1st Embodiment. It is an enlarged explanatory view which shows the shaft displacement measuring mechanism which concerns on 1st Embodiment in an enlarged manner. It is a schematic diagram which shows the pressure distribution between a rotating shaft body and a measuring plate. It is explanatory drawing which shows the structure of the shaft displacement measuring mechanism which concerns on 2nd Embodiment. It is explanatory drawing which shows the structure of the shaft displacement measuring mechanism which concerns on 3rd Embodiment.

<First Embodiment>
(1. Overall configuration of fluid bearing device 1)
An embodiment of a fluid bearing device embodying the present invention will be described with reference to the drawings. The fluid bearing device 1 according to the present invention statically supports a rotating shaft such as a grinding machine shaft, and controls the supply amount of fluid (lubricating oil in the present embodiment) according to the amount of vibration of the rotating shaft. Therefore, it is a bearing device configured to suppress the vibration of the rotating shaft body. As shown in FIG. 1, the fluid bearing device 1 includes a fluid bearing body 3, a pump P, a shaft displacement measuring mechanism 10, and a control device 90.

The fluid bearing body 3 is formed in a cylindrical shape having a space for accommodating the rotating shaft body 2, and concave static pressure pockets 4a to 4d facing the outer peripheral surface of the rotating shaft body 2 are provided on the inner peripheral surface in the circumferential direction. Four are arranged in. Specifically, the upper static pressure pocket 4a in the vertical direction and the lower static pressure pocket 4b are arranged to face each other, and the static pressure pocket 4c on the right side in the horizontal direction and the static pressure pocket 4d on the left side are arranged to face each other. Has been done. A fluid bearing is formed by supplying a fluid between the fluid bearing main body 3 and the rotating shaft body 2.

A fixed throttle 6a is provided in the flow path 5a for supplying lubricating oil from the pump P to the upper static pressure pocket 4a, and a variable throttle 6b is provided in the flow path 5b for supplying lubricating oil from the pump P to the lower static pressure pocket 4b. , Each is provided. Similarly, a fixed throttle 6c is in the flow path 5c for supplying lubricating oil from the pump P to the static pressure pocket 4c on the right side, and a variable throttle is in the flow path 5d for supplying lubricating oil from the pump P to the static pressure pocket 4d on the left side. 6d is provided respectively.

The variable diaphragms 6b and 6d are variable diaphragm devices that can change the opening degree of the diaphragm in response to a command. As the variable diaphragms 6b and 6d, a known diaphragm type variable diaphragm device is used in which a diaphragm is arranged opposite to a valve seat provided with an outflow path and the diaphragm is driven by an actuator such as a voice coil motor to change the opening degree. be able to. A specific configuration of the diaphragm type variable diaphragm device is described in, for example, Japanese Patent Application Laid-Open No. 2015-218827.

Further, an axial displacement measuring mechanism 10 having a displacement sensor 40 on the inner peripheral surface of the fluid bearing body 3 between adjacent static pressure pockets 4a and 4c, 4c and 4b, 4b and 4d, and 4d and 4a in the circumferential direction. Are provided respectively. The displacement sensor 40 is electrically connected to the control device 90, and transmits the measurement result of the axial displacement (swing) of the rotating shaft body 2 to the control device 90. Details of the shaft displacement measuring mechanism 10 will be described later.

The pump P pumps a fluid (hereinafter, lubricating oil) through the flow paths 5a to 5d to supply the lubricating oil to the static pressure pockets 4a to 4d. The control device 90 controls the opening degrees of the variable diaphragms 6b and 6d according to the shaft displacement received from the displacement sensor 40 of the shaft displacement measuring mechanism 10. For example, when the displacement sensor 40 adjacent to the static pressure pocket 4b detects a displacement indicating that the rotating shaft body 2 is approaching, control is performed to increase the opening degree of the variable diaphragm 6b, and the flow rate to the static pressure pocket 4b is performed. To increase. Alternatively, when the displacement sensor 40 adjacent to the static pressure pocket 4b detects a displacement indicating that the rotating shaft body 2 is moving away, control is performed to reduce the opening degree of the variable diaphragm 6b to reduce the flow rate to the static pressure pocket 4b. Reduce. By changing the pressure of the lubricating oil in the static pressure pockets 4b and 4d in this way, it is possible to suppress the vibration of the rotating shaft body 2.

(2. Configuration of Shaft Displacement Measuring Mechanism 10 (First Embodiment))
The shaft displacement measuring mechanism 10 is provided on the fluid bearing body 3 and is a mechanism for measuring the radial displacement of the rotating shaft body 2 in a non-contact manner. As shown in FIG. 2, the shaft displacement measuring mechanism 10 includes a case 20, a member to be measured 30, and a displacement sensor 40.

The case 20 is a lid-shaped housing, in which the displacement sensor 40 is housed in the inner sensor space 21, and the measurement target member 30 is fixed to the fluid bearing body 3. The case 20 has a curved bottom portion 22 along the outer surface of the fluid bearing body 3, and a displacement sensor 40 is attached to the center of the bottom portion 22 in the sensor space 21. The case 20 has an outer shape that matches the side opening 3a of the fluid bearing body 3, and is attached with the support portion 32 of the measurement target member 30 sandwiched between the case 20 and the step portion 3b of the side opening 3a. As a result, the case 20 closes the side opening 3a and fixes the measuring plate 31 between the rotating shaft body 2 and the displacement sensor 40 with a gap between them.

The case 20 is formed with an inflow hole 23 that penetrates the outside and the sensor space 21. The inflow hole 23 is connected to the pump P by the flow path 5e, and the flow path 5e is provided with a variable throttle 6e so that the flow rate of the lubricating oil flowing into the inflow hole 23 can be changed. Therefore, the flow rate of the lubricating oil supplied from the pump P is adjusted by the variable throttle 6e through the flow path 5e, and flows into the sensor space 21 from the inflow hole 23.

As shown in FIGS. 2 and 3, the measurement target member 30 includes a disk-shaped measuring plate 31 and a support portion 32 provided in a brim shape on the entire outer circumference of the measuring plate 31. The measurement target member 30 is formed by forming a measurement plate 31 and a support portion 32 from a single base material made of a metal material such as spring steel by shaving. The measuring plate 31 has a concave pocket portion 33 formed on the first surface facing the rotating shaft body 2, and the second surface facing the displacement sensor 40 is a flat measuring surface 34. It is a circular recess that is one size smaller than the outer circumference of the measuring plate 31, and has a nozzle hole 35 that penetrates to the second surface side on the bottom surface 33a of the pocket portion 33.

The support portion 32 is provided in an annular shape on the outer circumference of the measuring plate 31. The measurement target member 30 is attached to the outer peripheral portion of the case 20 by fitting the case 20 into the side opening 3a and fixing the case 20 with screws or the like (not shown) in a state where the support portion 32 is arranged along the step portion 3b in the side opening 3a. The support portion 32 is sandwiched and fixed between the step portion 3b and the step portion 3b. Since the support portion 32 has elasticity, the measuring plate 31 can move in a predetermined range in the radial direction of the rotating shaft body 2. That is, the support portion 32 elastically supports the measuring plate 31 with respect to the fluid bearing body 3 so as to be movable in the radial direction and non-rotatably. The measuring plate 31 can be moved in the range of, for example, several μm to several tens of μm.

The displacement sensor 40 is a known distance sensor. In the present embodiment, the eddy current sensor can be preferably used as the displacement sensor 40. The eddy current sensor is a sensor that measures the distance to the object to be measured using a high-frequency magnetic field. The eddy current sensor causes a high-frequency current to flow through a coil inside the sensor head to generate a high-frequency magnetic field. When a metal to be measured is present in this magnetic field, an electromagnetic induction action causes the passage of magnetic flux and eddy current in the vertical direction to flow on the surface of the object, and the impedance of the sensor coil changes. The eddy current displacement sensor measures the distance by changing the oscillation state due to this phenomenon. The eddy current sensor is resistant to water and oil and has excellent environmental resistance. The displacement signal detected by the displacement sensor 40 is amplified by the amplifier circuit 41 and sent to the control device 90.

Next, the position adjustment of the measuring plate 31 in the measurement target member 30 will be described. As described above, the measuring plate 31 is attached to the fluid bearing body 3 via the elastic support portion 32. Therefore, the measuring plate 31 stops at a position where the pressure in the sensor space 21 and the pressure of the static pressure oil film formed between the pocket portion 33 and the rotating shaft body 2 are pressed against each other to be in equilibrium. Therefore, after the member 30 to be measured is arranged at a predetermined position in the side opening 3a of the fluid bearing body 3 and the case 20 is attached and fixed, the pressure (primary pressure) of the lubricating oil supplied from the pump P to the sensor space 21 is appropriate. By setting to, the distance (gap) between the measuring plate 31 and the rotating shaft body 2 can be finely adjusted.

Hereinafter, the relationship between the distance (gap) between the measuring plate 31 and the rotating shaft body 2 and the pressure of the lubricating oil will be described. The primary pressure (supply pressure), which is the pressure of the lubricating oil supplied to the sensor space 21, is P ₁ [Pa], and the secondary pressure (pocket pressure), which is the pressure of the lubricating oil in the pocket portion 33, is P ₂ [Pa]. , The outer diameter area of the measuring plate 31 is A ₁ [m ² ], the distance between the measuring plate 31 and the rotating shaft 2 is h [m], and the resistance of the nozzle portion of the measuring plate 31 is K _d [m ³ / s. 1 / Pa], the area of the pocket portion 33 is A ₂ [m ² ], and the outflow resistance of the measuring plate 31 is K _h [m ³ / s · 1 / Pa]. Of these, the distance h between the secondary pressure (pocket pressure) P ₂ and the measuring plate 31 and the rotating shaft body 2 is an unknown value.

When the inner diameter (radius) of the sensor space 21 is r ₁ , the outer diameter area of the sensor space A ₁ = π _{r 1} ² [m ² ]. When the inner diameter (radius) of the pocket portion 33 is r ₂ , the pocket portion area A ₂ = π _{r 2} ² [m ² ].

The force balance is expressed by the following equation (1), and the flow rate balance is expressed by the equation (2).

By combining the above equations (1) and (2), the secondary pressure (pocket pressure) P ₂ and the distance h between the measuring plate 31 and the rotating shaft body 2 can be obtained. Therefore, after the member 30 to be measured is arranged at a predetermined position in the side opening 3a of the fluid bearing body 3 and the case 20 is attached and fixed, the primary pressure (supply pressure) is applied with the variable throttle 6e so that h becomes the target value. ) _{By adjusting P 1} , the measuring plate 31 can be stopped at a predetermined position. FIG. 5 is a schematic view showing the pressure distribution between the rotating shaft body 2 and the measuring plate 31. In FIG. 5, the length of the arrow represents the magnitude of the pressure, and it can be seen that there is a trapezoidal pressure distribution between the rotating shaft body 2 and the measuring plate 31.

In each configuration of the present embodiment described above, the flow path 5e, the variable throttle 6e, the inflow hole 23, and the pump P constitute the "fluid supply unit that supplies fluid from the outside to the inside of the fluid bearing body" of the present invention. Further, the measuring plate 31 constitutes "a measuring plate which is arranged on the outer periphery of the rotating shaft body with a gap between them and is arranged via a fluid film formed in the gap by the fluid". The support portion 32 constitutes "a support member that elastically supports the measuring plate in a radial direction with respect to the fluid bearing body and does not rotate." The displacement sensor 40 constitutes "a displacement sensor that is arranged to face the measuring plate in the sensor space on the opposite side of the rotating shaft and measures the displacement of the distance from the measuring plate".

(3. Action of Shaft Displacement Measuring Mechanism 10 (First Embodiment))
The operation of each part when measuring the displacement of the rotating shaft body 2 by the shaft displacement measuring mechanism 10 will be described. In the shaft displacement measuring mechanism 10, the sensor space 21 of the case 20 in which the displacement sensor 40 is housed is blocked by the measurement target member 30 from the space on the rotating shaft body 2 side. The lubricating oil that is pumped from the pump P and flows into the sensor space 21 through the inflow path is supplied into the pocket portion 33 of the measuring plate 31 through the nozzle hole 35, and static pressure is applied to the gap between the rotating shaft body 2 and the measuring plate 31. An oil film is formed.

The measuring plate 31 of the member 30 to be measured is stopped at a balanced position by pressing the pressure of the lubricating oil in the sensor space 21 and the pressure of the hydrostatic oil film against each other. When the rotating shaft body 2 swings in any of the radial directions, the measuring plate 31 is pressed through the hydrostatic oil film and is displaced by the same distance in the same radial direction as the swing of the rotating shaft body 2. Then, the displacement sensor 40 can measure the vibration of the rotating shaft body 2 by measuring the change in the distance from the measuring plate 31.

Then, the control device 90 controls the opening degrees of the variable diaphragms 26 and 28 according to the displacement of the rotating shaft body 2 received from the displacement sensor 40. As a result, the pressure of the lubricating oil in the static pressure pockets 4b and 4d changes, and the vibration of the rotating shaft body 2 is suppressed.

<Second Embodiment>
(4. Configuration of Shaft Displacement Measuring Mechanism 110 (Second Embodiment))
In the shaft displacement measuring mechanism 10 according to the first embodiment described above, the measuring plate 31 of the member 30 to be measured is configured to be arranged with respect to the rotating shaft body 2 via the hydrostatic oil film. The shaft displacement measuring mechanism 110 according to the embodiment is configured to be arranged via a dynamic pressure oil film generated by the rotation of the rotating shaft body 2. Hereinafter, the configuration of the shaft displacement measuring mechanism 110 according to the second embodiment will be described with reference to FIG. The same members as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. Further, the members corresponding to the first embodiment and different members are designated by adding 100 to the code of each part in the first embodiment.

As shown in FIG. 6, the shaft displacement measuring mechanism 110 according to the present embodiment includes a case 20, a measuring target member 130, and a displacement sensor 40. Since the configurations of the case 20 and the displacement sensor 40 are the same as those of the first embodiment, the description thereof will be omitted.

As shown in FIG. 6, the measurement target member 130 includes a disk-shaped measuring plate 131 and a support portion 132 provided in a collar shape on the outer periphery of the measuring plate 131. Unlike the measuring plate 31 of the first embodiment, the measuring plate 131 is not provided with a pocket portion on the first surface facing the rotating shaft body 2. Therefore, the first surface of the measuring plate 131 is a flat surface like the measuring surface 134 of the second surface facing the displacement sensor 40.

The basic configuration of the support portion 132 is the same as that of the support portion 32 according to the first embodiment, but the bearing space 3s and the sensor space 21 between the rotating shaft body 2 and the fluid bearing body 3 are provided at a plurality of locations. It differs from the support portion 32 in that a communication hole 135 that penetrates is provided.

In this embodiment as well as in the first embodiment, the pressure of the lubricating oil supplied from the pump P to the sensor space 21 after the measurement target member 130 is arranged in the side opening 3a of the fluid bearing body 3 and the case 20 is assembled. By appropriately setting the (primary pressure) and adjusting the pressure difference between the bearing space 3s and the sensor space 21, the distance (gap) between the measuring plate 131 and the rotating shaft body 2 can be adjusted with high accuracy. ..

(5. Action of Axis Displacement Measuring Mechanism 110 (Second Embodiment))
Next, the operation of each part when measuring the amount of runout of the rotating shaft body 2 by the shaft displacement measuring mechanism 110 according to the second embodiment will be described. In the shaft displacement measuring mechanism 110, the sensor space 21 of the case 20 in which the displacement sensor 40 is housed is shielded from the bearing space 3s on the rotating shaft body 2 side by the measuring plate 131. The lubricating oil that is pumped from the pump P and flows into the sensor space 21 through the inflow hole 23 flows into the bearing space 3s on the rotating shaft body 2 side through the communication hole 135. Then, when the rotating shaft body 2 rotates, a dynamic pressure oil film is formed in the gap between the rotating shaft body 2 and the measuring plate 131 due to the lubricating oil in the bearing space 3s.

The measuring plate 131 is stopped at a balanced position by pressing the pressure of the lubricating oil in the sensor space 21 and the pressure of the dynamic pressure oil film against each other. When the rotating shaft body 2 swings in any of the radial directions during rotation, the measuring plate 131 is pressed via the dynamic oil film and is displaced in the same direction as the swing of the rotating shaft body 2 by the same distance. The displacement sensor 40 can measure the amount of runout of the rotating shaft body 2 by measuring the distance displacement with the measuring plate 131.

Then, the control device 90 controls the opening degrees of the variable diaphragms 6b and 6d according to the displacement of the measuring plate 131 received from the displacement sensor 40. As a result, the pressure of the lubricating oil in the static pressure pockets 4b and 4d changes, and the vibration of the rotating shaft body 2 is suppressed.

<Third Embodiment>
(6. Configuration of Shaft Displacement Measuring Mechanism 210 (Third Embodiment))
In the shaft displacement measuring mechanism 10 according to the first embodiment and the shaft displacement measuring mechanism 110 according to the second embodiment described above, the sensor space 21 is filled with lubricating oil, but in the present embodiment, the inside of the sensor space is filled. Lubricating oil is supplied from the outside of the sensor space 21 to the bearing space 3s, and the measuring plate is arranged via the hydraulic oil film generated by the rotation of the rotating shaft body 2. Hereinafter, the configuration of the shaft displacement measuring mechanism 210 according to the third embodiment will be described with reference to FIG. The same members as those in the first and second embodiments are designated by the same reference numerals, and detailed description thereof will be omitted. Further, the members corresponding to the first embodiment and different members are designated by adding 200 to the code of each part in the first embodiment.

As shown in FIG. 7, the shaft displacement measuring mechanism 210 according to the present embodiment includes a case 220, a member to be measured 230, and a displacement sensor 40. Since the case 20 and the displacement sensor 40 are the same as those in the first embodiment, the description thereof will be omitted.

The basic configuration of the case 220 is the same as that of the case 20 of the first embodiment. However, unlike the case 20 of the first embodiment, the case 220 is not provided with an inflow hole 23 penetrating the inside and outside, and the sensor space 221 is not filled with lubricating oil. On the other hand, the fluid bearing body 3 is provided with inflow holes 3c penetrating inside and outside adjacent to the side opening 3a in the circumferential direction. The inflow hole 3c is connected to the pump P by the flow path 5f, and the flow path 5f is provided with a variable throttle 6f so that the flow rate of the lubricating oil flowing into the inflow hole 3c can be changed. Therefore, the flow rate of the lubricating oil supplied from the pump P is adjusted by the variable throttle 6f through the flow path 5f, and flows into the bearing space 3s between the rotating shaft body 2 and the fluid bearing body 3 from the inflow hole 3c. ..

As shown in FIG. 7, the measurement target member 230 includes a disk-shaped measuring plate 231 and a support portion 232 provided in a collar shape on the outer periphery of the measuring plate 231. The basic configuration of the measuring plate 231 is the same as that of the measuring plate 131 of the second embodiment. That is, unlike the measuring plate 31 of the first embodiment, the measuring plate 231 is not provided with the pocket portion 33 on the first surface facing the rotating shaft body 2, and the first surface is the second surface facing the displacement sensor 40. It is a flat surface like the measurement surface 234 of the surface.

The support portion 232 has the same configuration as the support portion 32 of the first embodiment. That is, unlike the support portion 132 of the second embodiment, the support portion 232 is not provided with the communication hole 135 penetrating the bearing space 3s on the rotating shaft body 2 side and the sensor space 21 side.

In the present embodiment, unlike the first embodiment and the second embodiment, the sensor space 221 is not filled with the lubricating oil but is filled with the atmosphere. Therefore, after the member 230 to be measured is arranged at a predetermined position in the side opening 3a of the fluid bearing body 3 and the case 220 is attached and fixed, the measuring plate utilizing the pressure difference of the lubricating oil in the spaces on both sides sandwiching the measuring plate 231 is used. The distance (gap) between the 231 and the rotating shaft body 2 is not finely adjusted.

(7. Action of Axis Displacement Measuring Mechanism 210 (Third Embodiment))
The operation of each part when measuring the amount of runout of the rotating shaft body 2 by the shaft displacement measuring mechanism 210 will be described. In the shaft displacement measuring mechanism 210, the sensor space 221 of the case 220 in which the displacement sensor 40 is housed is shielded from the bearing space 3s on the rotating shaft body 2 side by the measurement target member 230. The flow rate of the lubricating oil supplied from the pump P is adjusted by the variable throttle 6f through the flow path 5f, and flows into the bearing space 3s between the rotating shaft body 2 and the fluid bearing body 3 from the inflow hole 3c. Then, when the rotating shaft body 2 rotates, a dynamic pressure oil film is formed in the gap between the rotating shaft body 2 and the measuring plate 231 by the lubricating oil in the bearing space 3s.

The measuring plate 231 of the member 230 to be measured is stopped at a balanced position by pressing the pressure of the lubricating oil in the sensor space 221 and the pressure of the dynamic pressure oil film against each other. When the rotating shaft body 2 swings in any of the radial directions during rotation, the measuring plate 231 is pressed through the dynamic pressure oil film and is displaced by the same distance in the same direction as the swing of the rotating shaft body 2. Then, the displacement sensor 40 can measure the amount of runout of the rotating shaft body 2 by measuring the distance displacement with the measuring plate 231.

Then, the control device 90 controls the opening degrees of the variable diaphragms 6b and 6d according to the displacement of the measuring plate 231 received from the displacement sensor 40 (that is, the amount of deflection of the rotating shaft body 2). As a result, the pressure of the lubricating oil in the static pressure pockets 4b and 4d changes, and the vibration of the rotating shaft body 2 is suppressed.

(8. Summary)
According to the first embodiment described above, when the rotating shaft body 2 swings, the measuring plate 31 arranged on the rotating shaft body 2 via the oil film can be moved in the radial direction by the support portion 32 and rotates. Since it is elastically supported in an impossible manner, it moves according to the amount of runout of the rotating shaft body 2. When the measuring plate 31 moves, the displacement sensor 40 integrally arranged on the fluid bearing body 3 measures the displacement of the distance from the measuring plate 31. Therefore, by measuring the displacement of the measuring plate 31 that moves according to the runout of the rotating shaft body 2, it is possible to stably measure the amount of runout of the rotating shaft body 2 during rotation with high accuracy. .. Also in the second embodiment and the third embodiment, the same effect as that of the first embodiment is obtained.

Further, according to the first embodiment, the displacement sensor 40 is arranged to face the measuring plate 31 in the sensor space 21 on the side opposite to the rotating shaft body 2, and the pump P and the inflow hole 23 as the fluid supply unit are arranged. Is configured to supply lubricating oil to the sensor space 21 from the outside of the fluid bearing body 3, and the measuring plate 31 has a concave pocket portion 33 provided on a surface facing the rotating shaft body 2 and the inside of the pocket portion 33. It has a nozzle hole 35 that communicates with the sensor space 21, and a static pressure formed in the bearing space 3s with the rotating shaft body 2 by the lubricating oil supplied from the sensor space 21 into the pocket portion 33 through the nozzle hole 35. It is arranged via a hydrostatic oil film as a fluid film. According to this configuration, a hydrostatic oil film is surely formed between the rotating shaft body 2 and the measuring plate 31, and the measuring plate 31 is in a state of being integrally moved with the rotating shaft body 2 via the hydrostatic oil film. Can be done.

Further, according to the first embodiment, after the member 30 to be measured is attached to a predetermined position of the fluid bearing body 3 and mechanically adjusted, the measuring plate 31 is provided with lubricating oil in the pocket portion 33 and the sensor space 21. Since the reference position is adjusted with high accuracy by the pressure difference between the two, the amount of runout of the rotating shaft body 2 can be measured with high accuracy by measuring the distance displacement of the measuring plate 31 with the displacement sensor 40.

Further, according to the second embodiment, the measuring plate 131 is interposed via a dynamic pressure oil film as a dynamic pressure fluid film formed in a gap between the measurement plate 131 and the rotating shaft body 2 as the rotating shaft body 2 rotates. Is placed. According to this configuration, a dynamic pressure oil film is surely formed between the rotating shaft body 2 and the measuring plate 31, and the measuring plate 31 is in a state of being integrally moved with the rotating shaft body 2 via the dynamic pressure oil film. Can be done. The third embodiment also has the same effect.

In particular, in the third embodiment, the pump P and the inflow hole 3c as the fluid supply unit supply the lubricating oil to the outer periphery (bearing space 3s) of the rotating shaft body 2, so that when the rotating shaft body 2 is rotated, the measurement is performed. A dynamic pressure oil film can be reliably formed between the plate 231 and the plate 231.

Further, according to the second embodiment, the displacement sensor 40 is arranged to face the measuring plate 131 in the sensor space 21 on the side opposite to the rotating shaft body 2, and the pump P and the inflow hole 23 as the fluid supply unit are arranged. Is configured to supply lubricating oil to the sensor space 21, and the support portion 132 has a communication hole 135 communicating with the space on the rotating shaft body 2 side and the sensor space 21, and the sensor space 21 passes through the communication hole 135. The lubricating oil supplied to the outer periphery (bearing space 3s) of the rotating shaft body 2 is arranged via a hydraulic oil film formed in a gap as the rotating shaft body 2 rotates. According to this configuration, when the rotating shaft body 2 is rotated, a dynamic pressure oil film can be reliably formed between the rotating shaft body 2 and the measuring plate 131.

In particular, in the second embodiment, since the reference position of the measuring plate 131 is adjusted with high accuracy by the pressure difference of the lubricating oil between the bearing space 3s on the rotating shaft body 2 side and the sensor space 21, the displacement sensor 40 is used. By measuring the distance displacement of the measuring plate 31, the amount of runout of the rotating shaft body 2 can be measured with high accuracy.

Further, according to the first embodiment, the measuring plate 31 has a disk shape, and the support member 32 is provided in an annular shape on the outer circumference of the measuring plate 31. According to this configuration, the measuring plate 31 has a disk shape in which the distance from the center to the outer circumference is uniform, and the outer circumference of the measuring plate 31 is supported by the support member 32. Therefore, the measuring plate 31 is supported by the runout of the rotating shaft body 2. Can be moved in a stable posture. In particular, since the measuring plate 31 and the support portion 32 are integrally formed, the structure is simple and the assembly is easy. Also in the second embodiment and the third embodiment, the same effect as that of the first embodiment is obtained.

Further, according to the first embodiment, an opening in which the measuring plate and the support member are arranged is formed on the side surface of the fluid bearing body, and the sensor is attached to the opening in the opening. It is closed by a lid-like case that forms a space. The second and third embodiments have the same effect.

Further, according to the first embodiment, the measuring plate 31 is made of a metal material, and the displacement sensor 40 is an eddy current sensor. According to this configuration, as the displacement sensor 40 arranged in the sensor space 21 filled with lubricating oil, a vortex current sensor that is strong against water and oil and has excellent environmental resistance is used, and the distance from the measuring plate 31 is reached. Displacement can be measured. Then, even when the material characteristics and residual stress of the surface are continuously changed due to the rotation of the rotating shaft body 2, the same portion of the measuring plate 31 which is the object to be measured is measured, so that it is electrical. It has the effect of being able to perform stable and highly accurate displacement measurement without the influence of runout. The second and third embodiments have the same effect.

Further, according to the first embodiment, a side opening 3a in which the measurement target member 30 (measurement plate 31 and the support portion 32) is arranged is formed on the side surface of the fluid bearing body 3, and the side opening 3a is a displacement sensor. It is closed by a lid-shaped case 20 to which the 40 is attached and forms a sensor space 21 inside. According to this configuration, it is easy to assemble to the fluid bearing body 3, and it is possible to measure the amount of runout of the rotating shaft body 2 stably and with high accuracy.

(9. Other modified examples)
The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. For example, in the above embodiment, the measuring plate 31 and the support portion 32 are integrally formed by processing the same base material, but after the disk-shaped measuring plate and the annular support member are separately manufactured. , The support member may be fitted on the outer periphery of the measuring plate and united to be integrated. In this case, the measuring plate and the support member may use different base materials, for example, an iron-based metal material may be used as the material of the measuring plate, and a springy material such as spring steel may be used as the material of the support member. May be configured using.

Further, in each of the above embodiments, an example in which an eddy current sensor is used as the displacement sensor 40 is shown, but in the third embodiment, since the inside of the sensor space 221 is the atmosphere, another non-contact type distance sensor is used. You may use it. For example, a capacitance type or laser type distance sensor may be used.

Further, in each of the above embodiments, the displacement sensor 40 is arranged in the sensor space 21 or the like, but the present invention is not limited to this. The displacement sensor 40 may simply be integrally arranged with the fluid bearing body 3. Instead of the configuration in which the displacement sensor 40 is arranged radially outside the measuring plate 31, for example, the displacement sensor 40 is arranged at a position displaced in the axial direction with respect to the measuring plate 31 to measure the displacement in the radial direction. It may be configured to be.

2 ... Rotating shaft body, 3 ... Fluid bearing body, 3a ... Side opening, 3c ... Inflow hole, 4a to 4d ... Static pressure pocket, 5e ... Flow path (fluid supply unit (first and second embodiments)), 6e ... Variable throttle (fluid supply unit (1st and 2nd embodiments)), 10 ... Shaft displacement measuring mechanism, 20 ... Case (1st embodiment), 21 ... Sensor space (1st and 2nd embodiments), 23 ... Inflow hole (fluid supply part (first, second embodiment)), 31 ... Measuring plate (first embodiment), 32 ... Support part (support member (first embodiment)), 33 ... Pocket part, 35 ... Nozzle hole, 40 ... Displacement sensor, 110 ... Shaft displacement measuring mechanism (first embodiment), 131 ... Measuring plate (second embodiment), 132 ... Support portion (second embodiment), 135 ... Communication hole (first embodiment) 2), 210 ... Shaft displacement measuring mechanism (2nd embodiment), 220 ... Case (3rd embodiment), 221 ... Sensor space (3rd embodiment), 231 ... Measuring plate (3rd embodiment), 232 ... Support unit (third embodiment), P ... Pump (fluid supply unit).

Claims (11)

A fluid bearing device that supports the rotating shaft body by the pressure of the fluid filled between the rotating shaft body and the fluid bearing body.
A fluid supply unit that supplies the fluid from the outside to the inside of the fluid bearing body,
A measuring plate arranged on the outer periphery of the rotating shaft body with a gap, and arranged via a fluid film formed in the gap by the fluid.
A support member that elastically supports the measuring plate so as to be movable in the radial direction and non-rotatably with respect to the fluid bearing body.
A displacement sensor that is integrally arranged on the fluid bearing body and measures the displacement of the distance from the measuring plate.
Fluid bearing device. The displacement sensor is arranged to face the measuring plate in the sensor space on the side opposite to the rotating shaft body.
The fluid supply unit is configured to supply the fluid to the sensor space.
The measuring plate has a concave pocket portion on a surface facing the rotating shaft body and a nozzle hole that communicates the inside of the pocket portion with the sensor space, and the sensor space enters the pocket portion through the nozzle hole. The fluid bearing device according to claim 1, which is arranged via a hydrostatic fluid film formed in the gap between the rotating shaft body and the rotating shaft body by the supplied fluid. The fluid bearing device according to claim 2, wherein the measuring plate has a reference position adjusted by a pressure difference between the fluids in the pocket portion and the sensor space. The fluid bearing device according to claim 1, wherein the measuring plate is arranged via a dynamic fluid film formed in the gap as the rotating shaft body rotates. The fluid bearing device according to claim 4, wherein the fluid supply unit is configured to supply the fluid to the outer periphery of the rotating shaft body. The displacement sensor is arranged so as to face the measuring plate in the sensor space on the side opposite to the rotating shaft body.
The fluid supply unit is configured to supply the fluid to the sensor space.
The support member has a communication hole that communicates with the space on the rotating shaft body side and the sensor space, and the rotating shaft is provided by the fluid supplied from the sensor space to the outer periphery of the rotating shaft body through the communication hole. The fluid bearing device according to claim 4, which is arranged via a hydrodynamic fluid film formed in the gap as the body rotates. The fluid bearing device according to claim 6, wherein the measuring plate has a reference position adjusted by a pressure difference of the fluid between the space on the rotating shaft body side and the sensor space. The measuring plate has a disk shape and has a disk shape.
The fluid bearing device according to any one of claims 1 to 7, wherein the support member is provided in an annular shape on the outer circumference of the measuring plate. The fluid bearing device according to any one of claims 1 to 8, wherein the measuring plate and the support member are integrally formed. The measuring plate is made of a metal material and is made of a metal material.
The fluid bearing device according to any one of claims 1 to 9, wherein the displacement sensor is an eddy current sensor. On the side surface of the fluid bearing body, a side opening on which the measuring plate and the support member are arranged is formed.
The fluid bearing device according to any one of claims 1 to 10, wherein the side opening is closed by a lid-shaped case to which the displacement sensor is attached to form a sensor space inside.

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