Rigidity-variable magnetorheological fluid hydrostatic bearing device

Abstract

The invention discloses a magnetorheological fluid hydrostatic bearing device with variable rigidity. The magnetorheological fluid hydrostatic bearing device comprises a bearing, a rotating shaft, a permanent magnet, a rigidity adjusting coil, a rotating shaft coil, a framework seal and an axial nut, the rotating shaft is a stepped shaft and is provided with a plurality of journals which are symmetrically distributed, and rotating shaft coils are uniformly fixed on the outer side of the rotating shaft; radial oil inlet holes are uniformly distributed on the periphery of the bearing and are communicated with the oil cavity; permanent magnets are embedded on the bearing, and rigidity adjusting coils are distributed between the permanent magnets; the permanent magnet generates a stable magnetic field, and after the rigidity adjusting coil and the rotating shaft coil are electrified, the rheological property of the magnetorheological fluid is changed through superposition or interaction of the magnetized oil sealing edge and the magnetic field of the permanent magnet, so that the bearing torque of the bearing is increased, the bearing capacity is improved, and the bearing rigidity is flexibly adjusted. The magnetorheological fluid serves as a lubricating medium, the problem that the bearing capacity is reduced when a bearing runs at a high speed in traditional liquid lubrication is solved, damping and rigidity of the magnetorheological fluid are rapidly adjusted by controlling current, and the stability of a bearing device is enhanced so as to adapt to complex working conditions.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrostatic bearings, and particularly relates to a magnetorheological fluid hydrostatic bearing device with variable stiffness. Background Art

[0002] Hydrostatic bearings exhibit good lubrication and support effects under heavy loads, multi-source disturbances, etc., and are therefore widely used in machine tool spindles. As an intelligent fluid material that can be controlled by a magnetic field, magnetorheological fluid can be used as a controllable lubricant for hydrostatic bearings due to its unique magnetorheological effect. By controlling the magnitude of the external magnetic field, the clearance of the hydrostatic bearing can be maintained constant under different loads. At present, how to combine magnetorheological fluid with hydrostatic bearings to improve the bearing capacity, rotational accuracy, and load-carrying torque of the bearings has always been a research hotspot among scholars at home and abroad.

[0003] So far, many studies have improved the existing magnetorheological fluid hydrostatic bearings. The Chinese invention patent with the publication number CN108612757B discloses an active magnetorheological fluid hydrostatic bearing, which uses magnetorheological fluid as a lubricating medium. When the magnetorheological fluid flows through the stable magnetic field generated between the permanent magnet and the energized coil, the flow resistance increases, causing the support pressure in the support cavity to rise, effectively improving the bearing capacity of the bearing. The Chinese invention patent with the publication number CN114135582B discloses a semi-active hydrostatic bearing device lubricated with magnetorheological fluid, which uses two eddy current displacement sensors to detect the position of the transmission shaft relative to the hydrostatic bearing, and uses a controller to dynamically change the magnitude of the input current of the external excitation system, thereby changing the rheological parameters of the magnetorheological fluid.

[0004] However, the existing magnetorheological fluid hydrostatic bearings still have problems such as insufficient load capacity, small load-carrying torque, and difficulty in adapting to complex and changeable working conditions with strong interference. Summary of the Invention

[0005] In view of the above deficiencies in the prior art, the present invention provides a magnetorheological fluid bearing device with variable stiffness, which uses magnetorheological fluid as a lubricating medium, and respectively uses two sets of coils on the bearing and the rotating shaft to dynamically change the rheological properties of the magnetorheological fluid, change the bearing stiffness, and increase the load-carrying torque of the bearing to adapt to the change of working conditions.

[0006] The present invention adopts the following technical solutions: A magnetorheological fluid hydrostatic bearing device with variable stiffness, comprising: a bearing, a permanent magnet, a rotating shaft, and an axial nut;

[0007] A plurality of radial oil inlet holes are distributed on the outer circumference of the bearing, and the radial oil inlet holes communicate with the oil cavity. A radial oil outlet hole is also opened below the circumference of the bearing;

[0008] There are multiple permanent magnets, which are evenly embedded and fixed on the bearing, fixed by an axial nut, and a stiffness adjustment coil is distributed between every two permanent magnets;

[0009] The rotating shaft is a stepped shaft, with several journal bearings processed and symmetrically distributed, and multiple groups of rotating shaft coils are evenly distributed on the outer side of the rotating shaft;

[0010] After the stiffness adjustment coil and the rotating shaft coil are energized, they respectively magnetize the oil sealing edge, superimpose or interact with the magnetic field generated by the permanent magnet, and change the rheological properties of the magnetorheological fluid.

[0011] Preferably, there are 5 journal bearings, and the rotating shaft is sequentially divided into a first shaft section, a second shaft section, a third shaft section, a fourth shaft section, and a fifth shaft section from left to right;

[0012] The third shaft section is in the middle, the first shaft section and the fifth shaft section, and the second shaft section and the fourth shaft section are respectively on both sides of the third shaft section and are symmetric to each other.

[0013] Preferably, threads are processed on the journal bearings of the second shaft section and the fourth shaft section.

[0014] Preferably, a first skeleton seal and a second skeleton seal are respectively installed on both sides of the bearing to prevent the axial leakage of the magnetorheological fluid.

[0015] Preferably, there are four radial oil inlet holes, which are evenly distributed on the outer periphery of the bearing circumference; there are two radial oil outlet holes: a first radial oil outlet hole and a second radial oil outlet hole, which are respectively arranged on both sides below the bearing circumference.

[0016] Preferably, the outer side of the permanent magnet is the S pole and the inner side is the N pole, which is used to generate a continuous and stable magnetic field; there are two axial nuts: a first axial nut and a second axial nut, which are respectively arranged on both sides of the permanent magnet to axially fix the permanent magnet.

[0017] Preferably, the energizing current of the stiffness adjustment coil is adjustable. After the stiffness adjustment coil is energized, the first oil sealing edge on the inner side is magnetized, the inner side of the first oil sealing edge is the N pole, and the outer side is the S pole, which is superimposed with the magnetic field generated by the permanent magnet to change the flow damping when the magnetorheological fluid flows through and adjust the stiffness of the hydrostatic bearing.

[0018] Preferably, the energizing current of the rotating shaft coil is adjustable. After the rotating shaft coil is energized, the second oil sealing edge on the inner side is magnetized, the outer side of the second oil sealing edge is the N pole, and the inner side is the S pole, which interacts with the magnetic field generated by the permanent magnet to promote the relative rotation of the bearing and the rotating shaft and adjust the torque of the rotating shaft.

[0019] Preferably, the calculation formula for the stiffness of the hydrostatic bearing is:

[0020] ;

[0021] In the formula, is the basic stiffness of the hydrostatic bearing without current, which is determined by the magnetic field of the permanent magnet, is the stiffness adjustment coefficient, is the energizing current of the stiffness adjustment coil.

[0022] Preferably, the calculation formula for the torque of the rotating shaft is:

[0023] ;

[0024] In the formula, is the proportionality constant, which is related to the number of turns of the coil, the magnetic field gradient and the geometric parameters of the rotating shaft, is the energizing current of the rotating shaft coil.

[0025] Compared with the prior art by adopting the above technical solutions, the present invention has the following technical effects:

[0026] 1. The device of the present invention uses magnetorheological fluid as the lubricating medium, and respectively uses two groups of coils on the bearing and the rotating shaft to dynamically change the rheological properties of the magnetorheological fluid, solving the problem that in traditional liquid lubrication, when the bearing runs at high speed, the viscosity of the lubricating medium decreases, resulting in a decrease in the bearing load capacity;

[0027] 2. The device of the present invention can quickly change the damping and stiffness of the magnetorheological fluid at the lubrication part by controlling the magnitudes of the energizing currents of the stiffness adjustment coil and the rotating shaft coil, so as to flexibly change the bearing stiffness, increase the bearing load torque, improve the stability of the bearing device, and adapt to the change of working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic structural diagram of the magnetorheological fluid bearing device of the present invention;

[0029] Figure 2 is Figure 1 a sectional view taken along line A-A in

[0030] Figure 3 is a partial enlarged view of the coil and the permanent magnet of the present invention;

[0031] Figure 4 is a flowchart of the variable stiffness of the hydrostatic bearing of the present invention;

[0032] Description of the reference numerals: 1 - bearing, 2 - permanent magnet, 3 - stiffness adjustment coil, 4 - rotating shaft, 5 - rotating shaft coil, 6 - oil cavity, 7 - radial oil inlet hole, 8 - first shaft section, 9 - first skeleton seal, 10 - first axial nut, 11 - second axial nut, 12 - second skeleton seal, 13 - fifth shaft section, 14 - fourth shaft section, 15 - first radial oil outlet hole, 16 - third shaft section, 17 - second radial oil outlet hole, 18 - second shaft section. DETAILED DESCRIPTION OF THE INVENTION

[0033] To make the objectives, technical solutions and advantages of the present invention clearer, the following further elaborates on the technical solutions of the application in detail with reference to the accompanying drawings. The described embodiments are only a part of the embodiments related to the present invention. All non-innovative embodiments made by other researchers in the field based on this embodiment fall within the protection scope of the present invention.

[0034] In one embodiment of the present invention, a magnetorheological fluid hydrostatic bearing device with variable stiffness includes: bearing 1, permanent magnet 2, stiffness adjustment coil 3, rotating shaft 4, rotating shaft coil 5, oil cavity 6, radial oil inlet hole 7, first shaft section 8, first skeleton seal 9, second skeleton seal 12, first axial nut 10, second axial nut 11, fifth shaft section 13, fourth shaft section 14, first radial oil outlet hole 15, second radial oil outlet hole 17, third shaft section 16, and second shaft section 18.

[0035] Specifically, as Figure 1 shown, the rotating shaft 4 is a stepped shaft with 5 journal bearings, which are, from left to right, the first shaft section 8, the second shaft section 18, the third shaft section 16, the fourth shaft section 14, and the fifth shaft section 13.

[0036] Among them, the third shaft section 16 is in the middle, and the first shaft section 8 and the fifth shaft section 13, the second shaft section 18 and the fourth shaft section 14 are symmetric with each other on both sides of the third shaft section 16; the rotating shaft coil 5 is fixed on the third shaft section 16.

[0037] The permanent magnet 2 is fixed inside the bearing 1 and is fixed by the first axial nut 10 and the second axial nut 11 on the left and right sides, generating a constant magnetic field, which interacts with the magnetic field generated by the rotating shaft coil 5, increasing the torque of the rotating shaft; four radial oil inlet holes 7 are opened on the circumference of the bearing 1 and communicate with the oil cavity 6.

[0038] Specifically, taking the longitudinal midpoint of the third shaft section 16 as point A, the cross-sectional view of the A-A plane is as Figure 2 shown. The four radial oil inlet holes 7 are evenly distributed on the circumference of the bearing 1, and there is an oil cavity 6 left; the permanent magnet 2 and the stiffness adjustment coil 3 are alternately fixed inside the bearing 1; multiple groups of rotating shaft coils 5 are evenly distributed on the rotating shaft 4.

[0039] Particularly, in this embodiment, the magnetorheological fluid is used as the lubricating medium of the bearing device. The magnetorheological fluid enters the oil cavity 6 through the four radial oil inlet holes 7. The first skeleton seal 9 and the second skeleton seal 12 are respectively installed on the left and right sides of the bearing 1 to prevent the axial leakage of the magnetorheological fluid; the first radial oil outlet hole 15 and the second radial oil outlet hole 17 are respectively opened on both sides below the circumference of the bearing 1 for the magnetorheological fluid to flow out.

[0040] As Figure 3As shown, the outer side of the permanent magnet 2 is the S pole and the inner side is the N pole, which is used to generate a continuous and stable magnetic field; the inner side of the first oil-sealing edge inside the stiffness adjustment coil 3 is the N pole and the outer side is the S pole; the inner side of the second oil-sealing edge inside the rotating shaft coil 5 is the S pole and the outer side is the N pole.

[0041] In this embodiment, the hydrostatic bearing variable stiffness adjustment method is as Figure 4 shown, and includes the following steps:

[0042] Step 1: Set the target stiffness Kt of the hydrostatic bearing;

[0043] Step 2: Calculate the energizing current of the stiffness adjustment coil 3 required when the hydrostatic bearing reaches the target stiffness , the energizing current of the rotating shaft coil 5 ;

[0044] Step 3: Apply current to the stiffness adjustment coil 3, the magnetic field of the stiffness adjustment coil 3 is enhanced / reduced, the yield stress of the magnetorheological fluid increases / decreases, and the pressure in the oil cavity 6 rises or falls;

[0045] Step 4: Apply current to the rotating shaft 4 to promote the relative rotation of the bearing 1 and the rotating shaft 4 and adjust the torque of the rotating shaft 4;

[0046] Step 5: Monitor the stiffness of the hydrostatic bearing in real time, and repeat Steps 2 to 4 until the stiffness of the hydrostatic bearing reaches the target stiffness Kt.

[0047] Among them, the calculation formula for the stiffness of the hydrostatic bearing is:

[0048]

[0049] In the formula, is the basic stiffness without current, which is determined by the magnetic field of the permanent magnet, is the stiffness adjustment coefficient, which comprehensively considers the effects of magnetic permeability, coil parameters and structural dimensions, is the energizing current of the stiffness adjustment coil.

[0050] The calculation formula for the torque of the rotating shaft is:

[0051] ;

[0052] In the formula, is a proportionality constant, which is related to the number of coil turns, magnetic field gradient and geometric parameters of the rotating shaft, is the energizing current of the rotating shaft coil.

[0053] During use, after the stiffness adjustment coil 3 is energized, it superimposes with the magnetic field generated by the permanent magnet 2 to form a stable magnetic field. The magnetorheological fluid flowing through here undergoes the magnetorheological fluid effect under the action of the magnetic field. The viscosity of the magnetorheological fluid increases, the flow resistance increases, the pressure in the oil chamber 6 increases, and the load-bearing capacity of the bearing is improved. At this time, by adjusting the magnitude of the current, an additional magnetic field is generated to control the viscosity of the magnetorheological fluid, and the bearing stiffness can be flexibly changed.

[0054] Similarly, after the rotating shaft coil 5 is energized, the second oil sealing edge inside the rotating shaft coil 5 is magnetized. The inner side of the second oil sealing edge is the S pole, which repels the inner N pole of the permanent magnet 2, promoting the rotational movement of the rotating shaft 4, thereby increasing the torque and adapting to complex and changeable working conditions.

[0055] In summary, the magnetorheological fluid hydrostatic bearing device of the present invention has a simple structure. Using the magnetorheological fluid as the lubricating medium, with the help of two groups of coils on the bearing and the rotating shaft respectively, the rheological properties of the magnetorheological fluid are dynamically changed, so that the bearing stiffness can be changed and the load-bearing torque of the bearing can be increased.

[0056] The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A magnetorheological fluid hydrostatic bearing device with variable stiffness, characterized in that, Comprising: a bearing (1), a permanent magnet (2), a rotating shaft (4) and an axial nut; A plurality of radial oil inlet holes (7) are distributed on the circumferential periphery of the bearing (1), and the radial oil inlet holes (7) communicate with the oil cavity (6). A radial oil outlet hole is also opened below the circumference of the bearing (1); There are multiple permanent magnets (2), which are evenly fixed on the bearing (1) and fixed by an axial nut. A stiffness adjustment coil (3) is distributed between every two permanent magnets (2); The rotating shaft (4) is a stepped shaft, with several journal shafts processed and symmetrically distributed. Multiple groups of rotating shaft coils (5) are evenly distributed on the outer side of the rotating shaft (4); After the stiffness adjustment coil (3) and the rotating shaft coil (5) are energized, they respectively magnetize the oil sealing edge, and superimpose or interact with the magnetic field generated by the permanent magnet (2) to change the rheological properties of the magnetorheological fluid.

2. The magnetorheological hydrostatic bearing device with variable stiffness according to claim 1, characterized in that There are 5 journal shafts. The rotating shaft (4) is successively divided into a first shaft section (8), a second shaft section (18), a third shaft section (16), a fourth shaft section (14) and a fifth shaft section (13) from left to right; The third shaft section (16) is in the middle. The first shaft section (8) and the fifth shaft section (13), and the second shaft section (18) and the fourth shaft section (14) are respectively on both sides of the third shaft section (16) and are symmetrical to each other.

3. The magnetorheological hydrostatic bearing device with variable stiffness according to claim 2, characterized in that, Threads are processed on the journal shafts of the second shaft section (18) and the fourth shaft section (14).

4. The magnetorheological hydrostatic bearing device with variable stiffness according to claim 1, characterized in that A first skeleton seal (9) and a second skeleton seal (12) are respectively installed on the left and right sides of the bearing (1) to prevent the axial leakage of the magnetorheological fluid.

5. The magnetorheological hydrostatic bearing device with variable stiffness according to claim 1, characterized in that, There are four radial oil inlet holes (7), which are evenly distributed on the circumferential periphery of the bearing (1); there are two radial oil outlet holes: a first radial oil outlet hole (15) and a second radial oil outlet hole (17), which are respectively arranged on both sides below the circumference of the bearing (1).

6. The magnetorheological hydrostatic bearing device with variable stiffness according to claim 5, characterized in that, The outer side of the permanent magnet (2) is the S pole and the inner side is the N pole, which is used to generate a continuous and stable magnetic field; there are two axial nuts: a first axial nut (10) and a second axial nut (11), which are respectively arranged on both sides of the permanent magnet (2) to axially fix the permanent magnet (2).

7. The magnetorheological hydrostatic bearing device with variable stiffness according to claim 6, characterized in that, The energizing current of the stiffness adjustment coil (3) can be adjusted. After the stiffness adjustment coil (3) is energized, the first oil sealing edge on the inner side is magnetized. The inner side of the first oil sealing edge is the N pole and the outer side is the S pole, which is superimposed with the magnetic field generated by the permanent magnet (2) to change the flow damping when the magnetorheological fluid flows through and adjust the stiffness of the hydrostatic bearing.

8. The magnetorheological hydrostatic bearing device with variable stiffness according to claim 7, characterized in that The energizing current of the rotating shaft coil (5) can be adjusted. After the rotating shaft coil (5) is energized, the second oil sealing edge on the inner side is magnetized. The outer side of the second oil sealing edge is the N pole and the inner side is the S pole, which interacts with the magnetic field generated by the permanent magnet (2) to promote the relative rotation of the bearing (1) and the rotating shaft (4) and adjust the torque of the rotating shaft (4).

9. The magnetorheological hydrostatic bearing device with variable stiffness according to claim 8, characterized in that, The calculation formula for the stiffness of the hydrostatic bearing is: ； In the formula, is the basic stiffness of the hydrostatic bearing without current, which is determined by the magnetic field of the permanent magnet, is the stiffness adjustment coefficient, is the energizing current of the stiffness adjustment coil (3).

10. The magnetorheological hydrostatic bearing device with variable stiffness according to claim 8, characterized in that, The calculation formula for the torque of the rotating shaft (4) is: ； In the formula, is a proportionality constant related to the number of turns of the coil, the magnetic field gradient, and the geometric parameters of the rotating shaft. is the current flowing through the coil of the rotating shaft (4).

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