WO2020250246A1

WO2020250246A1 - Hydrostatic controller for maintaining constant fluid film gap

Info

Publication number: WO2020250246A1
Application number: PCT/IN2020/050520
Authority: WO
Inventors: Ramanan KUMAR; Sudhanva BHAT; Vishal PAIDIMARRI; Pradeep KUMAR PRAKASAM; Sathyan Subbiah; Ramesh BABU NIMMAGADDA; Kapil DHAND; Anant JAIN; Prakash SADHASIVAM
Original assignee: INDIAN INSTITUTE OF TECHNOLOGY MADRAS (IIT Madras); Micromatic Grinding Technologies Limited
Priority date: 2019-06-11
Filing date: 2020-06-11
Publication date: 2020-12-17
Also published as: TW202108908A; TWI824158B

Abstract

Embodiments herein disclose a hydrostatic controller for maintaining a constant fluid film gap. The hydrostatic controller includes a fixed restrictor (106 or 402) configured to provide a fixed resistance in the hydrostatic controller. The fixed restrictor (106 or 402) is connected in series with a variable restrictor (108 or 404). The variable restrictor (108 or 404) is configured to provide a variable resistance in the hydrostatic controller. The variable restrictor (108 or 404) is connected in line with a recess pocket (112 or 410). The fixed resistance has a geometry of a capillary restrictor. The variable resistance comprises a geometry, wherein the geometry deforms to actively control a flow rate in the hydrostatic controller, wherein the geometry is provided by the circular member (102 or 406).

Description

HYDROSTATIC CONTROLLER FOR MAINTAINING CONSTANT

FLUID FILM GAP

FIELD OF INVENTION

[0001] The present disclosure relates to a hydrostatic bearing system, and more specifically related to a hydrostatic controller for maintaining a constant fluid film gap in the hydrostatic bearing system. The present application is based on, and claims priority from an Indian Application Number 201941023121 filed on June 11, 2019 and an Indian Application Number 201941023123 filed on June 11, 2019 the disclosure of which are hereby incorporated by reference herein.

BACKGROUND

[0002] A hydrostatic bearing system is a non-contact type bearing system that guides fluid such as air, lubrication oil or the like to an inside thereof and obtains a load capacity by a restricting effect. Although, the hydrostatic bearing system has advantages such as low friction and a high moving accuracy due to an averaging effect, it has disadvantages such as low stiffness and low damping characteristic. In order to improve the stiffness of the hydrostatic bearing system, it is effective to minimize the bearing clearance. In addition, to optimally design a bearing with a small bearing clearance, the amount of a fluid that flows in the bearing system should be restricted corresponding to the bearing clearance.

[0003] However, when the bearing clearance is decreased, the machining accuracy of the bearing should be improved. Thus, there is a limitation on the improvement of the stiffness of the bearing by means of a decrease of the bearing clearance. To overcome the limitation, various variable restricting mechanisms have been proposed.

[0004] In an example, a working mechanism of a flow controller using flat and spherical membranes in series, with two different flow resistance having thin restricting gap, directly connected to the one of hydrostatic pocket is presence in existing hydrostatic bearing system. In existing hydrostatic bearing systems, a conventional flow restrictors are fixed flow resistances and flow rate will decrease when recess pressure changes in a hydrostatic pocket. The equation of flow rate is as follows, Q = (Supply pressure - Recess Pressure) / (Fixed resistance).

[0005] Thus, it is desired to address the above mentioned disadvantages or other shortcomings or at least provide a useful alternative.

OBJECT OF INVENTION

[0006] The principal object of the embodiments herein is to provide a flow controlling unit for maintaining a constant fluid film gap in a hydrostatic bearing system.

[0007] Another object of the embodiments herein is to provide a hydrostatic bearing film thickness controller using a cylindrical tube diaphragm.

SUMMARY

[0008] Accordingly, embodiments herein disclose a hydrostatic controller for maintaining a constant fluid film gap. The hydrostatic controller includes a circular member and a fixed restrictor. The fixed restrictor is configured to provide a fixed resistance in the hydrostatic controller, where the fixed restrictor is connected in series with a variable restrictor. The variable restrictor is configured to provide a variable resistance in the hydrostatic controller. The variable restrictor is connected in line with a recess pocket. The fixed resistance has a geometry of a capillary restrictor. The variable resistance comprises a geometry. The geometry deforms to actively control a flow rate in the hydrostatic controller, wherein the geometry is provided by the circular member. [0009] In an embodiment, the variable resistance is provided using a clearance created by the circular member and an annular land.

[0010] In an embodiment, the fixed restrictor is connected in series with the circular member through the variable restrictor and a capillary system to create a pressure gradient across the circular member.

[0011] In an embodiment, the circular member is a circular flat membrane and a cylindrical tube diaphragm.

[0012] In an embodiment, the hydrostatic controller is a flow controlling unit or a hydrostatic bearing film thickness controller.

[0013] In an embodiment, the circular member is a circular flat membrane and a cylindrical tube diaphragm.

[0014] Accordingly, embodiments herein disclose a flow controlling unit for maintaining a constant fluid film gap in a hydrostatic bearing system. The flow controlling unit includes a circular flat membrane, an annular land, and a fixed restrictor providing a fixed resistance in the flow controlling unit. The fixed restrictor is connected in series with a variable restrictor. The variable restrictor provides a variable resistance in the flow controlling unit, wherein the variable restrictor is connected in line with a recess pocket. The fixed resistance has a geometry of a capillary restrictor. The variable resistance comprises a geometry, where the geometry of the variable resistance deforms to actively control a flow rate in the hydrostatic bearing system. The geometry of the variable resistance is provided by the circular flat membrane. The variable resistance is provided using a clearance created by the circular flat membrane and the annular land.

[0015] In an embodiment, the fixed resistance enables a requisite pressure difference to develop across the circular flat membrane.

[0016] In an embodiment, the fixed resistance maintains a correct gradient of pressure difference across the circular flat membrane. [0017] In an embodiment, a cross section of the clearance is determined by a deformation of the circular flat membrane.

[0018] In an embodiment, a pressure difference across the circular flat membrane controls amount of deformation in the circular flat membrane.

[0019] In an embodiment, the fixed resistance chokes a fluid flow so as to control a large flow rate of the fluid flow from flowing through the variable restrictor.

[0020] In an embodiment, the clearance is provided at a specific supply pressure.

[0021] Accordingly, embodiments herein disclose a hydrostatic bearing system comprises an oil sump, a pressure relief value, a pump, a motor, an accumulator, a filter, a hydraulic power pack, a bearing pocket, and a flow controlling unit. The flow controlling unit includes a circular flat membrane which is a variable restrictor, an annular land, and a fixed restrictor providing a fixed resistance in the flow controlling unit. The fixed restrictor is connected in series with a variable restrictor. The variable restrictor provides a variable resistance in the flow controlling unit, wherein the variable restrictor is connected in line with a recess pocket. The fixed resistance has a geometry of a capillary restrictor. The variable resistance comprises a geometry, where the geometry of the variable resistance deforms to actively control a flow rate in the hydrostatic bearing system. The geometry of the variable resistance is provided by the circular flat membrane. The variable resistance is provided using a clearance created by the circular flat membrane and the annular land.

[0022] Accordingly, embodiments herein disclose a hydrostatic bearing film thickness controller includes a fixed restrictor configured to provide a fixed resistance in the hydrostatic bearing film thickness controller. The fixed restrictor is connected in series with a variable restrictor. The variable restrictor is configured to provide a variable resistance in the hydrostatic bearing film thickness controller, wherein the variable restrictor is connected in line with a recess pocket. The fixed resistance comprises a geometry of a capillary restrictor. The variable resistance comprises a geometry, wherein the geometry deforms to actively control a flow rate in the hydrostatic bearing film thickness controller. The geometry is provided by a cylindrical tube diaphragm. The fixed restrictor is connected in series with the cylindrical tube diaphragm through variable restrictor and a capillary system to create a pressure gradient across the cylindrical tube diaphragm.

[0023] In an embodiment, the cylindrical tube diaphragm is configured such that a stress variation across the cylindrical tube diaphragm is minimized.

[0024] In an embodiment, the cylindrical tube diaphragm is constructed with variable thickness to improve bending characteristics of the cylindrical tube diaphragm.

[0025] In an embodiment, a supply pressure on an inside part of the cylindrical tube diaphragm provides a bulging in the cylindrical tube diaphragm towards a thin restricting clearance.

[0026] In an embodiment, the thin restricting clearance through the variable resistance maintains a change in gap in the cylindrical tube diaphragm.

[0027] In an embodiment, a supply pressure on an inside part of the cylindrical tube diaphragm forms a narrow radial clearance part. The narrow radial clearance part connects directly to the recess pocket.

[0028] In an embodiment, the cylindrical tube diaphragm is configured such that a deformation is closer to a desired average deflection of the cylindrical tube diaphragm. [0029] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.

BRIEF DESCRIPTION OF FIGURES

[0030] This method is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:

[0031] FIG. 1 is a cross sectional view of a flow controlling unit for maintaining a constant fluid film gap in a hydrostatic bearing system, according to an embodiment as disclosed herein;

[0032] FIG. 2 is a schematic view of a hydrostatic bearing system, according to an embodiment as disclosed herein;

[0033] FIG. 3 is a cross-sectional view of multiple flow controlling units connected in series and assembled as a single unit which is connected to the hydrostatic bearing system, according to an embodiment as disclosed herein; and

[0034] FIG. 4 is a cross sectional view of a hydrostatic bearing film thickness controller, according to an embodiment as disclosed herein. DETAILED DESCRIPTION OF INVENTION

[0035] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well- known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. Also, the various embodiments described herein are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments. The term“or” as used herein, refers to a non exclusive or, unless otherwise indicated. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein can be practiced and to further enable those skilled in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.

[0036] The accompanying drawings are used to help easily understand various technical features and it should be understood that the embodiments presented herein are not limited by the accompanying drawings. As such, the present disclosure should be construed to extend to any alterations, equivalents and substitutes in addition to those which are particularly set out in the accompanying drawings. Although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are generally only used to distinguish one element from another.

[0037] Accordingly, embodiments herein disclose a flow controlling unit for maintaining a constant fluid film gap in a hydrostatic bearing system. The flow controlling unit includes a circular flat membrane, an annular land, and a fixed restrictor providing a fixed resistance in the flow controlling unit. The fixed restrictor is connected in series with a variable restrictor. The variable restrictor provides a variable resistance in the flow controlling unit, wherein the variable restrictor is connected in line with a recess pocket. The fixed resistance has a geometry of a capillary restrictor. The variable resistance comprises a geometry, where the geometry of the variable resistance deforms to actively control a flow rate in the hydrostatic bearing system. The geometry of the variable resistance is provided by the circular flat membrane. The variable resistance is provided using a clearance created by the circular flat membrane and the annular land.

[0038] Unlike conventional methods and system, the flow controlling unit controls the hydrostatic bearing film thickness using a circular flat membrane. The flow controlling unit compensates by supplying more fluid to increase the load bearing capacity and stiffness of the bearing.

[0039] Further, the tube diaphragm is fixed around a thin circular slot or thin restricting gap and it has many advantages over a flat membrane as the tube diaphragm can be easily attached but flat membrane requires press fit to hold at the edges of membrane in the assembly of hydrostatic bearing film thickness controller. The flow rate of the fluid depends on the pressure difference among the supply and recess pressure and flow resistance of restricting clearance. The flow resistance of the clearance is controlled by a change in the restricting gap caused by deflection of tube diaphragm due to fixed resistance.

[0040] The geometry of the variable resistance is provided by a cylindrical tube diaphragm in order to deform and actively control the flow rate in the hydrostatic bearing film thickness controller. The deflection of tube diaphragm allows more fluid into the loaded recess pocket thereby regulating stiffness and hydrostatic system film gap thickness. [0041] Referring now to the drawings, and more particularly to FIGS. 1 through 4, there are shown preferred embodiments.

[0042] FIG. 1 is a cross sectional view of a flow controlling unit (100) for maintaining a constant fluid film gap in a hydrostatic bearing system (200), according to an embodiment as disclosed herein.

[0043] In general, the hydrostatic bearing system (200) is in demand because the hydrostatic bearing system (200) is able to achieve high stiffness. In order to achieve high stiffness, the flow controlling unit (100) is required to maintain a constant fluid film gap in the hydrostatic bearing system (200). In an embodiment, the flow controlling unit (100) includes a circular flat membrane (102), an annular land (104), and a fixed restrictor (106) configured to provide a fixed resistance in the flow controlling unit (100). The fixed restrictor (106) is connected in series with a variable restrictor (108). The variable restrictor (108) is configured to provide a variable resistance in the flow controlling unit (100). The variable restrictor (108) is connected in line with a recess pocket (112) (i.e., bearing pocket). The fixed resistances and the variable resistance help in regulating the fluid flow in the flow controlling unit (100). The fixed resistance has the geometry of a capillary restrictor. The variable resistance includes a geometry which can deform and thereby actively control the flow rate. The geometry of the variable resistance is provided by the circular flat membrane (102). The fixed resistance enables the requisite pressure difference to develop across the circular flat membrane (102) so that the circular flat membrane (102) can deform as intended. The fixed resistance also chokes the flow so as to prevent a large flow rate of fluid from flowing through it. The fixed resistance also helps to maintain the correct gradient of pressure difference across the circular flat membrane (102) so that the circular flat membrane (102) does not deflect in the direction opposite to what is intended. [0044] Further, the variable resistance is achieved via a clearance (110) created by the circular flat membrane (102) and the annular land (104). The clearance (110) is optimized for the best performance at the given operating supply pressure of 25 bar. A cross section of the clearance (110) is determined by the magnitude of membrane deformation. Higher the deformation of the membrane lesser is the clearance cross sectional area. The pressure difference across the circular flat membrane (102) helps to control amount of deformation in the circular flat membrane (102) and in turn the clearance (110). When there is a change in the bearing gap, the thin restricting clearance in variable resistance of the controlling unit (100) changes to compensate the change in the gap. The increase in load increases the recess pressure thus decreasing the bearing film gap. The controlling unit (100) compensates by supping more fluid to increase the load bearing capacity and stiffness of the bearing. This indicates a positive slope between the pressure and fluid flow rate which leads to ideal performance and this is achieved via the controlling unit (100).

[0045] As the recess pressure increases the flow controlling unit (100) causes a simultaneous increase in the flow rate using a variable restrictor. This helps to maintain bearing gap height for enough stiffness so that the hydrostatic bearing system (200) can provide the required precision and accuracy

[0046] Further, the thickness of the circular flat membrane (102) and restricting gap can be used to control the performance of the variable resistance. The circular flat membrane (102) is easily mounted and fixed. The design is easy to manufacture and implement.

[0047] The model of the flow controlling unit (100) has been tested in a lab using a hydrostatic bearing test rig. An output performance shows an increase in flow rate as the load increases, this load increases the recess pressure and tends to increase flow resistance of bearing pocket and hydrostatic bearing film thickness would start decreasing. This can be prevented by increasing the flow rate by an external flow controlling mechanism. Using a diaphragm to decrease the flow resistance of bearing pocket will help in maintaining a constant film thickness and achieve desired performance.

[0048] FIG. 2 is a schematic view of the hydrostatic bearing system (200), according to an embodiment as disclosed herein. The hydrostatic bearing system (200) includes a hydraulic power pack (214), an oil sump (202), a pressure relief value (204), a pump (206), a motor (208), an accumulator (210), a filter (212), and a bearing pocket (216), and the flow controlling unit (100). The hydraulic power pack (214) is used to pressurize the oil which generates the supply pressure (P_s). The pressurized oil is supplied to the flow controlling unit (100) which has a fixed resistance (106) and a variable resistance (102). The oil passes through the flow controlling unit (100) and proceeds to the recess pocket (112) which creates a recess pressure (P_r).

[0049] FIG. 3 is a cross-sectional view of multiple flow controlling units (100) connected in series and assembled as a single unit which is connected to the hydrostatic bearing system (200). The arrangement and function of the flow controlling unit (100) is already explained in conjunction with the FIG. 1 and FIG. 2.

[0050] The load carrying capacity of the hydrostatic bearing system (200) and stiffness is dependent on the fixed resistance of the flow controlling unit (100). The capillary restrictor is used as the fixed restrictor (106) and parameters of the fixed restrictor (106) are majorly the diameter of capillary and the length of capillary.

[0051] FIG. 4 is a cross sectional view of a hydrostatic bearing film thickness controller (400), according to an embodiment as disclosed herein. In an embodiment, the hydrostatic bearing film thickness controller (400) includes a fixed restrictor (402) configured to provide a fixed resistance in the hydrostatic bearing film thickness controller (400). The fixed restrictor (402) is connected in series with a variable restrictor (404). The variable restrictor (404) is configured to provide a variable resistance in the hydrostatic bearing film thickness controller (400), wherein the variable restrictor (404) is connected in line with a recess pocket (410).

[0052] Further, the fixed resistance has geometry of a capillary restrictor. The variable resistance comprises a geometry which can deform and thereby actively control the flow rate. The geometry of the variable restrictor is provided by a cylindrical tube diaphragm (406). The fixed restrictor (402) modeled using a capillary system is connected in series with the variable resistance of the cylindrical tube diaphragm (406), to create a pressure gradient across the cylindrical tube diaphragm (406).

[0053] Design of the cylindrical tube diaphragm (406) is in such way that stress variation across the cylindrical tube diaphragm (406) is minimized. The length (411) of the cylindrical tube diaphragm (406) is designed with variable thickness to improve its bending characteristics. The cylindrical tube diaphragm (406) has a smaller cross-sectional thickness (412) on edges of a cylinder (414) which tapers and increases to form a thicker cross section in a middle portion of another cylinder (413). The cylindrical tube diaphragm (406) is designed such that the deformation is closer to the desired average deflection of the cylindrical tube diaphragm (406) rather than having an uneven deformation along its length. The supply pressure on the inside of the tube diaphragm (406) results in bulging of the tube diaphragm (406) towards the thin restricting clearance (408). The thin restricting clearance (408) connects directly to the recess pocket (410) of bearing varies as incoming recess pressure variations occur. The deflection of the tube diaphragm (406) allows more fluid into the loaded recess pocket thereby regulating stiffness and hydrostatic system film gap thickness. When there is a change in the bearing gap, the thin restricting clearance (408) (i.e., annular land gap) in the variable resistance changes to compensate the change in gap. The increase in load increases recess pressure thus decreasing the bearing film gap. The hydrostatic bearing film thickness controller (400) compensates by supping more fluid to increase the load bearing capacity and stiffness of the bearing. This indicates a positive slope between the pressure and fluid flow rate which leads to ideal performance and this is achieved via the hydrostatic bearing film thickness controller (400).

[0054] The variable thickness reduces the maximum deflection that can be obtained while keeping the average deflection constant therefore it can reduce maximum gap without fluid passage getting blocked thus achieving a greater percentage in the average gap thickness.

[0055] The tube diaphragm (406) is fixed around a thin circular slot or thin restricting gap and it has many advantages over a flat membrane as the tube diaphragm (406) can be easily attached but flat membrane requires press fit to hold at the edges of membrane in the assembly of hydrostatic bearing film thickness controller (400). The flow rate of the fluid depends on the pressure difference among the supply and recess pressure and flow resistance of restricting clearance. The flow resistance of the clearance is controlled by a change in the restricting gap caused by deflection of tube diaphragm due to fixed resistance.

[0056] The hydrostatic bearing film thickness controller (400) has been tested in a lab fabricated single pocket hydrostatic bearing test rig where, the recess pressure which tends to increases with flow resistance of bearing pocket, is varied. The hydrostatic bearing film thickness then starts to decrease, this can be prevented by increasing the flow rate via the external flow controlling mechanism which is the tube diaphragm, to decrease flow resistance of bearing pocket that will maintain constant film thickness.

[0057] The embodiments disclosed herein can be implemented using at least one software program running on at least one hardware device and performing network management functions to control the elements.

[0058] The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

Claims

CLAIMS We claim:

1. A hydrostatic controller for maintaining a constant fluid film gap in a hydrostatic bearing system (200), comprising:

a member (102 or 406);

a fixed restrictor (106 or 402) configured to provide a fixed resistance in the hydrostatic controller, wherein the fixed restrictor (106 or 402) is connected in series with a variable restrictor (108 or 404); and

the variable restrictor (108 or 404) configured to provide a variable resistance in the hydrostatic controller, wherein the variable restrictor (108 or 404) is connected in line with a recess pocket (112 or 410),

wherein the fixed resistance has a geometry of a capillary restrictor, and wherein the variable resistance comprises a geometry that deforms to actively control a flow rate in the hydrostatic bearing system (200), wherein the geometry is provided by the member (102 or 406).

2. The hydrostatic controller of claim 1 , wherein the fixed restrictor ( 106 or 402) is connected in series with the circular member (102 or 406) through the variable restrictor (108 or 404) and a capillary system to create a pressure gradient across the member (102 or 406).

3. The hydrostatic controller of claim 1 , wherein the member ( 102 or 406) is one of a circular flat membrane (102) and a cylindrical tube diaphragm (406).

4. The hydrostatic controller of claim 3, wherein the fixed resistance enables a requisite pressure difference to develop across the member (102).

5. The hydrostatic controller of claim 3, wherein the fixed resistance maintains a correct gradient of pressure difference across the member (102).

6. The hydrostatic controller of claim 3, further comprising an annular land (104), wherein the variable resistance is provided using a clearance (110) created by the member (102) and the annular land (104).

7. The hydrostatic controller of claim 6, wherein a cross section of the clearance (110) is determined by a deformation of the member (102).

8. The hydrostatic controller of claim 6, wherein the clearance (110) is provided at a specific supply pressure.

9. The hydrostatic controller of claim 3, wherein a pressure difference across the member (102) controls amount of deformation in the member (102).

10. The hydrostatic controller of claim 3, wherein the fixed resistance chokes a fluid flow so as to control a large flow rate of the fluid flow from flowing through the variable restrictor (108 or 404).

11. The hydrostatic controller of claim 3, wherein the member (406) is configured such that a stress variation across the member (406) is minimized.

12. The hydrostatic controller of claim 3, wherein the member (406) is constructed with variable thickness to improve bending characteristics of the member (406).

13. The hydrostatic controller of claim 3, wherein a supply pressure on an inside part of the member (406) provides a bulging in the member (406) towards a thin restricting clearance (408).

14. The hydrostatic controller of claim 13, wherein the thin restricting clearance (408) through the variable resistance maintains a change in gap in the member (406).

15. The hydrostatic controller of claim 3, wherein a supply pressure on an inside part of the member (406) forms a narrow radial clearance part, wherein the narrow radial clearance part connects directly to the recess pocket (112 and 410).

16. The hydrostatic controller of claim 3, wherein the member (406) is configured such that a deformation is closer to a desired average deflection of the member (406).

17. The hydrostatic controller of claim 3, wherein the member (406) comprises a smaller cross- sectional thickness (412) on edges of a cylinder (414) which tapers and increases to form a thicker cross section in a middle portion of another cylinder (413).

18. The hydrostatic controller of claim 1, wherein the hydrostatic controller is a flow controlling unit (100) or a hydrostatic bearing film thickness controller (400).

19. A hydrostatic bearing system (200), comprising:

an oil sump (202);

a pressure relief value (204);

a pump (206);

a motor (208);

an accumulator (210);

a filter (212); a hydraulic power pack (214);

a bearing pocket (216); and

a hydrostatic controller comprising:

a member (102 or 406);

a fixed restrictor ( 106 or 402) configured to provide a fixed resistance in the hydrostatic controller, wherein the fixed restrictor (106 or 402) is connected in series with a variable restrictor (108 or 404); and

wherein the fixed resistance has a geometry of a capillary restrictor, wherein the variable resistance comprises a geometry, wherein the geometry deforms to actively control a flow rate in the hydrostatic bearing system (200), wherein the geometry is provided by the member (102 or 400).

20. The hydrostatic bearing system (200) of claim 19, wherein the fixed restrictor (106 or 402) is connected in series with the member (102 or 406) through the variable restrictor (108 or 404) and a capillary system to create a pressure gradient across the member (102 or 406).

21. The hydrostatic bearing system (200) of claim 19, wherein the member (102 or 406) is one of a circular flat membrane (102) and a cylindrical tube diaphragm (406).

22. The hydrostatic bearing system (200) of claim 21, wherein the fixed resistance enables a requisite pressure difference to develop across the member (102).

23. The hydrostatic bearing system (200) of claim 21, wherein the fixed resistance maintains a correct gradient of pressure difference across the member (102).

24. The hydrostatic bearing system (200) of claim 21, further comprising an annular land (104), wherein the variable resistance is provided using a clearance (110) created by the member (102) and the annular land (104).

25. The hydrostatic bearing system (200) of claim 24, wherein a cross section of the clearance (110) is determined by a deformation of the member (102).

26. The hydrostatic bearing system (200) of claim 24, wherein the clearance (110) is provided at a specific supply pressure.

27. The hydrostatic bearing system (200) of claim 21, wherein a pressure difference across the member (102) controls amount of deformation in the member (102).

28. The hydrostatic bearing system (200) of claim 21, wherein the fixed resistance chokes a fluid flow so as to control a large flow rate of the fluid flow from flowing through the variable restrictor (108 or 404).

29. The hydrostatic bearing system (200) of claim 21, wherein the member (406) is configured such that a stress variation across the member (406) is minimized.

30. The hydrostatic bearing system (200) of claim 21 , wherein the member (406) is constructed with variable thickness to improve bending characteristics of the member (406).

31. The hydrostatic bearing system (200) of claim 21, wherein a supply pressure on an inside part of the member (406) provides a bulging in the member (406) towards a thin restricting clearance (408).

32. The hydrostatic bearing system (200) of claim 31 , wherein the thin restricting clearance (408) through the variable resistance maintains a change in gap in the member (406).

33. The hydrostatic bearing system (200) of claim 21, wherein a supply pressure on an inside part of the member (406) forms a narrow radial clearance part, wherein the narrow radial clearance part connects directly to the recess pocket (112 and 410).

34. The hydrostatic bearing system (200) of claim 21, wherein the member (406) is configured such that a deformation is closer to a desired average deflection of the member (406).

35. The hydrostatic bearing system (200) of claim 21 , wherein the member (406) comprises a smaller cross-sectional thickness (412) on edges of a cylinder (414) which tapers and increases to form a thicker cross section in a middle portion of another cylinder (413).

36. The hydrostatic bearing system (200) of claim 19, wherein the hydrostatic controller is a flow controlling unit (100) or a hydrostatic bearing film thickness controller (400).