JP2000120687A - Static pressure bearing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cope with the unexpected external force and a lack of performance without reworking and reassembling a bearing by providing a mechanism for changing the characteristic of a static pressure bearing and a control device for operating the described mechanism. SOLUTION: A static pressure bearing device 10 is provided with four pockets 21 surrounding a rotary shaft 11 with an equal space in the circumferential direction, and the pockets 21 are formed in the inner peripheral surface of a double-cylindrical bearing member 23. The lubricating fluid having the evened pressure is supplied to the pockets 21 through a throttle part 25. A bearing member 23 is fixed to the inner peripheral surface of a casing 24 through an actuator 22, and the fitting position of the bearing member 23 is changed in the radial direction by the electric signal, and a clearance between the rotary shaft 11 and the bearing member 23 is controlled, and the throttle part 25 is provided with an actuator 26 so as to adjust the degree of throttle on the basis of the electric signal. The actuators and the degree of throttle are controlled by a control device 33 in response to the displacement, speed and acceleration of the rotary shaft 11 so as to improve the performance, and generation of unexpected condition can be overcome without reworking and reassembling the bearing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrostatic bearing device for a rotary machine, and more particularly to a hydrostatic bearing device for supporting the rotary shaft by a static pressure of a fluid supplied from a bearing disposed on the outer periphery of the rotary shaft. About.

[0002]

2. Description of the Related Art A hydrostatic bearing device is a non-contact type bearing in which a fluid is guided to a rotating shaft side from a plurality of pockets provided in a bearing member and the rotating shaft is basically supported by utilizing the static pressure. is there. For this reason, the friction is small, and it is suitable for supporting a rotating shaft that rotates at high speed, and there is no problem such as wear of the bearing. When such a hydrostatic bearing device is used to support a rotating shaft of a turbo machine such as a pump, a part of the liquid to be handled is supplied to the bearing from the discharge side of the pump, so that the rotating shaft is non-contact supported by its own liquid. can do.

[0003] The characteristics of such a hydrostatic bearing include a bearing diameter, a bearing width, a pocket shape, determined at the time of design, processing, assembly, and the like.
It is determined by the shape of the bearing, such as the aperture shape, and the mounting position of the bearing. The operating characteristics of the hydrostatic bearing also change depending on the supply pressure and discharge pressure of the lubricating fluid during operation.

However, in a turbomachine or the like in which a rotating shaft is supported by a hydrostatic bearing device, when the machine is actually installed on the site and started to operate, unexpected external forces not taken into consideration at the time of design may be applied. A situation where the vibration exceeds the allowable value may occur. In such a case, it is necessary to re-design, process, adjust the assembly, etc. of the hydrostatic bearing device, which requires extra time and cost.

Further, in the conventional hydrostatic bearing device, since various parameters for determining the bearing performance are fixed, even if vibration or the like is generated on the rotating shaft, it is not possible to apply a damping force thereto.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and can cope with unexpected external forces and lack of performance without reworking and reassembling the bearing. An object of the present invention is to provide a hydrostatic bearing device.

[0007]

According to a first aspect of the present invention, there is provided a hydrostatic bearing device for supporting a rotating shaft by the pressure of fluid supplied from a plurality of pockets provided in a bearing. And a control device for operating the mechanism.

Thus, the actuator is operated,
By changing the characteristics of the hydrostatic bearing, it is possible to reduce the vibration of the rotating shaft. Accordingly, it is possible to cope with unexpected external force and lack of performance without reworking and reassembling the bearing, thereby improving the economics and working efficiency of the hydrostatic bearing.

The invention according to claim 2 is characterized in that the mechanism changes the characteristics of the hydrostatic bearing by changing the mounting position of the bearing with an actuator. It is a hydrostatic bearing device of the description. Thus, the mounting position of the bearing can be changed by the control signal supplied to the actuator, and the relative position (eccentric position) of the rotating shaft to the bearing can be changed. Various parameters such as a bearing reaction force, a bearing stiffness, and a damping coefficient change due to a change in the relative position of the rotating shaft with respect to the bearing, so that optimum bearing characteristics can be obtained.

According to a third aspect of the present invention, the mechanism changes the characteristic of the hydrostatic bearing by changing an aperture diameter of the bearing by an actuator. It is a hydrostatic bearing device of the description. Thereby, the bearing reaction force, the bearing rigidity, or the damping force acting on the rotating shaft can be changed. The invention according to claim 4 is characterized in that the mechanism changes a characteristic of the hydrostatic bearing by changing a supply source pressure of a fluid as a lubricant of the bearing. A hydrostatic bearing device according to (1).

[0011] Thus, the supply pressure of the fluid can be changed corresponding to the shaft vibration. Therefore, for example, during operation in a steady state in which shaft vibration does not occur, it is possible to reduce the fluid pressure, thereby reducing the amount of fluid leakage and maintaining good efficiency of the hydrostatic bearing.

According to a fifth aspect of the present invention, in the hydrostatic bearing device, at least three or more sets are arranged at different positions along the axial direction, so that different radial forces are applied to the bearing devices of each set. The hydrostatic bearing device according to claim 1, wherein the hydrostatic bearing device can be provided.

[0013] Thus, different radial bias static pressures are applied to each of at least three sets of hydrostatic bearing devices arranged at different positions along the axial direction, and the vector sum of the bias static pressures is reduced to zero. It can be. A bias static pressure is applied to each set of hydrostatic bearing devices, so that the overall bearing rigidity can be increased. Further, by setting the vector sum of the bias static pressures of each set to zero, the static pressures acting on the rotating shaft as a whole are balanced, and the movement of the rotating shaft position is not accompanied. Therefore, it is possible to increase the bearing rigidity as a whole without involving the movement of the position of the rotary shaft, thereby providing good control sensitivity in accordance with the adjustment of the throttle opening or the displacement of the bearing mounting position. it can.

According to a sixth aspect of the present invention, the hydrostatic bearing device further comprises means for detecting the vibration of the rotating shaft, and a mechanism for changing the characteristics of the bearing based on the detection result. The hydrostatic bearing device according to claim 1, wherein: Therefore, by appropriately designing the control device, it is possible to apply a damping force to the shaft vibration and actively dampen the shaft vibration. Thus, even if the shaft vibration is generated on the rotating shaft for some reason, this can be quickly and automatically reduced, and the bearing performance can be remarkably improved.

According to a seventh aspect of the present invention, there is provided a rotary machine including the hydrostatic bearing device according to any one of the first to sixth aspects.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a cross section along a rotation axis of a hydrostatic bearing device according to an embodiment of the present invention, and FIG.
FIG. 2B shows a cross section along the line BB.

The rotating shaft 11 is supported by a hydrostatic bearing device 10 in the radial direction. In the case of this embodiment, the hydrostatic bearing device 10 includes four pockets 21 arranged so as to surround the rotating shaft at equal intervals in the circumferential direction, and supports the rotating shaft 11 at substantially the center of the bearing. A static fluid pressure distribution is formed. The pocket 21 is a substantially rectangular concave portion formed on the inner peripheral surface of the double cylindrical bearing member 23,
Due to the static pressure of the lubricating fluid passing through this part, the rotating shaft 1
1 is supported. The hollow portion 23a between the double cylinders of the bearing member 23 is a reservoir for the lubricating fluid, and the lubricating fluid equalized here is supplied to the pocket 21 through the throttle unit 25. The lubricating fluid is supplied to the hollow portion 23a from a supply hole 29a which is a part of the pipe 29. In addition, 1
In the set of hydrostatic bearing devices, in the illustrated example, the pocket 2
Although 1 is four, six or eight pockets may of course be arranged.

A bearing member 23 is fixed to the inner peripheral surface of the casing 24 via an actuator 22. Here, a piezoelectric element is employed as the actuator 22, and the mounting position of the bearing member 23 is changed in the radial direction by supplying an electric signal, whereby the rotating shaft 11 and the bearing member 2 are changed.
3 is controlled. The diaphragm unit 25 includes an actuator 26 that can be electrically displaced, and the degree of diaphragm can be adjusted by inputting an electric signal to the actuator 26. The supply pressure of the lubricating fluid is controlled from a supply port 16 of the supply source by a source pressure adjusting valve 17,
9. After passing through the flexible pipe 28, the pressure is equalized from the supply hole 29a in the double cylindrical bearing member 23a. The fluid pressure is adjusted for each individual pocket through the throttle portions 25 and 26, and the fluid pressure is applied to the rotating shaft 11 through the pocket 21. In the pocket 21, the pressure of the lubricating fluid supplied in the rectangular recess becomes uniform, and a uniform static pressure is supplied to the rotating shaft 11, thereby holding the rotating shaft 11 from the bearing member 23 in a non-contact manner.

Therefore, in one set of the hydrostatic bearing device 10, the bearing members 2 are provided at four locations on the circumference at 90 ° intervals.
By arranging 3, static pressure is applied to the rotating shaft 11 from four directions, thereby supporting the rotating shaft 11 so as to be positioned substantially at the center of the bearing including its own weight.
The distribution of the static pressure applied to the rotating shaft 11 is individually adjusted using the throttles 25 and 26 and the regulator 17.

FIG. 3 shows the relationship between the eccentricity and the bearing reaction force with the difference in the aperture diameter as a parameter. Here, assuming that the contraction diameter of the radial hydrostatic bearing is Φ = 2.0 mm, the change in the bearing reaction force due to the amount of eccentricity is shown by the dotted line in FIG. However, the change in the bearing reaction force due to the amount of eccentricity when the drawing diameter is Φ = 0.5 mm is shown by the solid line in FIG. Here, assuming that there is no change in the static load applied to the bearing, point A on the dotted line corresponds to point B on the solid line. Therefore, by changing the aperture diameter from 2.0 mm to 0.5 mm, the operating point of the rotating shaft can be moved from the point A to the point B.

FIG. 4 shows the relationship between the eccentricity and the bearing rigidity. The dotted line in the figure is the case where the aperture diameter is Φ = 2.0 mm. Further, the solid line in the figure is the case where Φ = 0.5 mm. Kxx, Kxy, etc. indicate the stiffness in the x and y directions with respect to the displacement in the x direction, respectively.

FIG. 5 similarly shows the relationship between the eccentricity and the damping coefficient. The dotted line in the figure shows the case where the aperture diameter is Φ = 2.0 mm, and the solid line in the figure shows the case where Φ = 0.5 mm. Similarly, Cxx, Cxy, etc. indicate the x-direction and y-direction damping coefficients for the x-direction speed, respectively.

Accordingly, it is understood that various characteristics such as bearing reaction force, bearing rigidity, and damping coefficient can be obtained by changing the diameter of the throttle and the eccentricity. Also, as shown in FIG. 3, it can be seen that by changing the eccentricity, which is the relative position of the rotary shaft to the bearing, a bias static pressure corresponding to the aperture diameter is applied to the rotary shaft.

Therefore, in the hydrostatic bearing device 11, by setting the parameters such as the aperture diameter so as to be at the point A or the point B, respectively, the rigidity or the damping at the point C and the point D in FIGS. Coefficients can be used.

In the hydrostatic bearing device according to this embodiment, as shown in FIG. 1, a displacement sensor 31 for detecting the vibration of the rotating shaft 11 is arranged near the shaft, whereby the rotating shaft 1
1 is output. The output of the displacement sensor 31 is input to the vibrometer 32, where a displacement signal, a speed signal obtained by differentiating the displacement signal, an acceleration signal obtained by further differentiating the speed signal, and the like are formed and input to the control device 33. The control device 33 supplies a signal current for generating a control force for suppressing the vibration to the actuator 22 based on the vibration signal of the rotating shaft 11. The actuator 22 is, for example, a piezoelectric element as described above, and displaces the position of the bearing member 23 in the radial direction according to an electric signal supplied thereto. Thus, the radial static pressure applied to the rotating shaft 11 can be changed, and a damping force can be applied to the vibration of the rotating shaft 11 by an appropriate design of the control device 33.

As described above, since the mounting position of the bearing member 23 changes, a flexible pipe 28 is provided, and a seal 27 for sealing the pipe and the casing 21 is provided. Similarly, the diaphragm units 25 and 26 also include an actuator such as a piezoelectric element, and the degree of diaphragm can be adjusted by a signal from the control device 33. Therefore, by controlling the aperture in response to the signal of the displacement sensor, the rotation axis 11
Can be changed. As a result, it is possible to apply a damping force to the vibration of the rotating shaft 11, and it is also possible to hold the rotating shaft 11 at a predetermined target position.

As described above, these control characteristics are controlled by the control device 3
3, the actuator or the variable throttle diameter is controlled in accordance with the displacement, speed, acceleration, and the like of the rotating shaft detected by the vibrometer 32, so that the vibration generated on the rotating shaft is attenuated. Can be controlled.

In the above-described characteristic examples, the relationship between the eccentricity and the throttle diameter and the parameters such as the reaction force of the bearing has been described. However, a similar characteristic curve exists for the relationship between the lubricating fluid supply port 29a and the original pressure. By using this, the supply pressure of the lubricating fluid may be controlled. That is, the lubricating fluid supply port 29a
The control valve is inserted into the control valve 33, and the opening of the control valve is adjusted in response to the output of the control device 33. Thus, the feedback control of the control valve in response to the vibration of the rotating shaft detected by the vibration meter 32 makes it possible to reduce the vibration of the rotating shaft.

If the source pressure at the lubricating fluid supply port is high, the amount of leakage of the lubricating fluid of the hydrostatic bearing device increases, and the efficiency of the bearing decreases. Therefore, when vibration does not occur in the rotating shaft, the supply pressure of the lubricating fluid is reduced as much as possible, thereby reducing the amount of leakage of the bearing, thereby increasing the efficiency of the hydrostatic bearing. Further, in such a hydrostatic bearing, when the rotating shaft 11 is eccentric with the rotation of the rotating shaft 11, a dynamic force is generated which restores the eccentricity. It is held in non-contact with the member 23.

FIGS. 6 and 7 show examples in which three or more sets of bearing devices each comprising a plurality of pockets for supporting a rotating shaft are arranged at different positions along the axial direction. In each set of bearing devices, it is possible to apply a force in a different radial direction.

Each of the hydrostatic bearing devices 12, 13, 1 shown in FIG.
4, the degree of opening of the throttle 25 of each bearing member 23 arranged in the circumferential direction is not uniform, and different hydrostatic bearing devices 12, 13 and 14 are provided in different units in radial directions. A bias static pressure is applied to the rotating shaft 11, and the adjustment is performed so that the vector sum thereof becomes zero.

FIG. 7 shows another type of hydrostatic bearing device.
In this embodiment, the basic configuration is the same as the embodiment shown in FIG. The difference is that the control target of the control device is the opening degree of the aperture 25, which is a variable aperture mechanism using a piezoelectric element as an actuator. With the diaphragm provided with such a variable mechanism using the piezoelectric element, a high-speed response is obtained, and a small and stable operation is expected. The second difference is that the hydrostatic bearing devices 12, 13, and 14 as a unit are arranged adjacently and intensively along the axial direction of the rotating shaft. This makes it possible to configure a hydrostatic bearing device having a high bearing rigidity and a compact structure as a whole.

FIGS. 8 (a), 8 (b) and 8 (c) show the results of simulations about the rotation of the rotating shaft.
The basic formula of the bearing fluid force in the above-described hydrostatic bearing is represented by each of [Equation 1], [Equation 2], and [Equation 3]. Here, the basic expression of [Expression 1] indicates the flow in the rotational direction, the basic expression of [Expression 2] indicates the axial flow, and the basic expression of [Expression 3] indicates the continuity of the flow rate.

[0035]

(Equation 1)

(Equation 2)

(Equation 3)

(Equation 4)

(Equation 5)

(Equation 6)

(Equation 7)

Here, as shown in FIGS. 9 and 10, the symbols are as follows: θ: circumferential displacement z: axial displacement e: eccentricity P: pressure P _s : supply pressure of fluid μ: viscosity coefficient r of fluid : Shaft radius c: Bearing radius clearance (gap between shaft and bearing when the shaft is located at the center of the bearing) L: Bearing width ω: Rotational angular velocity ε: Eccentricity (e / c) Q: Supply of hydrostatic bearing Flow rate.

When the basic formula of the bearing fluid force is calculated by the difference method, the rotating state of the rotating shaft at the point A in FIG. 3 is as shown in FIG. 8A. In this case, the aperture is 2.0 mmφ, 5000 rpm, and the eccentricity is 30%. The bearing rigidity at this time is as follows: Kxx = 6.59 × 10 ⁷ (N / m) Kxy = 1.51 × 10 ⁷ (N / m) Kyx = −2.46 × 10 ⁷ (N / m) Kyy = 5.09 × 10 ⁷ (N / m) Further, the attenuation coefficient is Cxx = 9.53 × 10 ⁴ (Ns / m) Cxy = 4.39 × 10 ³ (Ns / m) Cyx = 4.33 × 10 ³ (N · s / m) Cyy = 8.03 × 10 ⁴ (N · s / m) At this time, the load on the rotating shaft is 120 kg.

FIG. 8B shows a state close to the point B in FIG. That is, an aperture of 0.5 mmφ, 5000 rpm,
The eccentricity is 90%. In this case, it can be seen that the touch around in the X direction is eliminated and only the whirling in the Y direction exists. The rigidity at this time is as follows: Kxx = 1.77 × 10 ⁸ (N / m) Kxy = 1.07 × 10 ⁸ (N / m) Kyx = −3.61 × 10 ⁷ (N / m) Kyy = 6.65 × 10 ⁶ (N / m) Further, the attenuation coefficient at this time is as follows: Cxx = 5.82 × 10 ⁵ (Ns / m) Cxy = −6.55 × 10 ⁴ (Ns / m ) Cyx = −7.16 × 10 ⁴ (N · s / m) Cyy = 9.80 × 10 ⁴ (N · s / m)

FIG. 8 (c) shows a preload of 40 kg applied to the center bearing using three bearings as shown in FIG. 6 or 7 at an angle of 45 ° with respect to the Y direction. Is the case. That is, the aperture is 0.5 mmφ, 5000 rpm
m and eccentricity of 95%. In this case, X
It can be seen that all the touches in the direction and the Y direction have been eliminated. The rigidity at this time is as follows: Kxx = 4.05 × 10 ⁸ (N / m) Kxy = 2.72 × 10 ⁸ (N / m) Kyx = 3.30 × 10 ⁷ (N / m) Kyy = 9 0.01 × 10 ⁸ (N / m) Further, the attenuation coefficient at this time is as follows: Cxx = 8.11 × 10 ⁵ (N · s / m) Cxy = 1.96 × 10 ⁵ (N · s / m) Cyx = 1.80 × 10 ⁵ (N · s / m) Cyy = 2.20 × 10 ⁵ (N · s / m) By applying a preload as shown in FIG. You can see that

In the above-described embodiment, an example has been described in which the actuator is formed by a piezoelectric element. However, the actuator may be formed by using a hydraulic device or the like. or,
The control parameters are not limited to the throttle diameter, the mounting position of the bearing, and the like, but can be similarly applied to various other parameters related to the hydrostatic bearing characteristics. Furthermore, although the above-described embodiment is directed to an example of a radial hydrostatic bearing, the gist of the present invention can be similarly applied to an axial hydrostatic bearing.

[0041]

According to the present invention as described above,
The bearing characteristics of the hydrostatic bearing can be controlled to be optimal according to the state of vibration of the rotating shaft. As a result, the performance of the hydrostatic bearing is improved, and without reworking and reassembling the bearing, external forces not expected at the time of design,
Even if a use condition is encountered, the bearing can be covered by such control of the bearing characteristics, and the economic efficiency and the working efficiency of the hydrostatic bearing can be improved. Thus, the operation of the rotating machine that supports the rotating shaft with the hydrostatic bearing can be stably and economically performed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a hydrostatic bearing device according to an embodiment of the present invention.

FIG. 2A is a cross-sectional view taken along the line AA of FIG.
(B) It is sectional drawing which followed the BB line.

FIG. 3 is a graph showing a relationship between an eccentricity and a bearing reaction force.

FIG. 4 is a graph showing the relationship between the eccentricity and the bearing stiffness.

FIG. 5 is a graph showing a relationship between an eccentricity and a damping coefficient.

FIG. 6 is a view showing an example in which a plurality of sets of the hydrostatic bearing device shown in FIG. 1 are arranged along the axial direction.

FIG. 7 is a diagram showing a modification of FIG. 6;

FIG. 8 is a diagram illustrating a simulation result (left side) of whirling of a rotating shaft and a preload application state (right side).

FIG. 9 is a diagram in which various parameters of a basic formula of a bearing fluid force are defined, and (a) is a cross-sectional view of a plane perpendicular to a rotation axis;
(B) is a sectional view of a plane along the rotation axis.

10A and 10B are diagrams in which various parameters of a basic formula of a bearing fluid force are defined, FIG. 10A is a developed view of a bearing surface along a line AA in FIG. 9, and FIG. It is an enlarged view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Static pressure bearing device 11 Rotary shaft 12, 13, 14 Static pressure bearing device as a unit 16 Lubricating fluid supply port 21 Pocket 22 Actuator 23 Bearing 24 Casing 25 Throttle 26 Regulator 27 Seal part 28 Flexible piping 31 Displacement sensor 32 Vibration 33 controllers in total

Claims (7)

[Claims] 1. A hydrostatic bearing device for supporting a rotating shaft by pressure of fluid supplied from a plurality of pockets provided in a bearing, a mechanism for changing characteristics of the hydrostatic bearing, and a control device for operating the mechanism. And a hydrostatic bearing device. 2. The hydrostatic bearing device according to claim 1, wherein the mechanism changes a characteristic of the hydrostatic bearing by changing a mounting position of the bearing with an actuator. 3. The hydrostatic bearing device according to claim 1, wherein the mechanism changes a characteristic of the hydrostatic bearing by changing a throttle diameter of the bearing with an actuator. 4. The static pressure according to claim 1, wherein the mechanism changes a characteristic of the hydrostatic bearing by changing a supply pressure of a fluid as a lubricant for the bearing. Bearing device. 5. The hydrostatic bearing device is characterized in that by arranging at least three or more sets along the axial direction, it is possible to apply forces in different radial directions in each set of bearing devices. The hydrostatic bearing device according to claim 1, wherein 6. The hydrostatic bearing device according to claim 1, further comprising: means for detecting vibration of the rotating shaft; and a mechanism for changing a characteristic of the bearing based on a result of the detection. Item 2. The hydrostatic bearing device according to item 1. 7. A rotary machine comprising the hydrostatic bearing device according to claim 1. Description: